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Internet Technologies in Manufacturing - I -
Diskussionsbeiträge des Instituts für Wirtschaftswissenschaften der Universität Klagenfurt
No. 2005/01
Internet-Technologies in Manufacturing – Applications and Management
Thorsten Blecker / Günter Graf / Bernd Kaluza
Universität Klagenfurt Institut für Wirtschaftswissenschaften
Universitätsstr. 65 – 67
A - 9020 Klagenfurt Telefon: (+43) 0463 / 2700 - 4007 Telefax: (+43) 0463 / 2700 - 4097
Dezember 2005
DISCUSSION PAPER OF THE COLLEGE OF BUSINESS ADMINISTRATION UNIVERSITY OF KLAGENFURT, AUSTRIA
ISBN 3-85496-026-3
Internet Technologies in Manufacturing - II -
Table of Contents Page
Table of Figures IV
1 Introduction 1
2 Fundamentals of Internet-Technologies in Manufacturing 2
2.1 Fundamentals and Origins 2
2.1.1 Hardware 4
2.1.2 Protocols 5
2.1.3 Services 7
2.2 Application in Operations 10
2.3 Selected Services and Languages 17
3 Information System Architectures for modern Operation Systems 21
3.1 Manufacturing Execution Systems 21
3.1.1 Integration Gap between Planning Layer and Process Control Layer 21
3.1.2 Vertical Integration of the Planning Layer and the Process control layer 23
3.2 Service Oriented Architectures (SOA) 25
3.2.1 Technological Deficits in current Information System Architectures for Enterprise Resource Planning (ERP) 25
3.2.2 Service-oriented Architecture as a Solution to ERP-Deficits 28
3.3 Internet-based Multi-Agent Systems (MAS) 32
3.3.1 Rationales for MAS – the example of Mass Customization 32
3.3.2 Recent Results in applied research 35
4 Managerial Approaches for Internet-based Operation Systems 37
4.1 Human Machine Interaction as critical Issue for ubiquitous Internet-based Infrastructures 37
4.1.1 Advances in Human Machine Interaction 37
4.1.2 Consequences of web-based HMI 41
4.1.3 Implementation of web-based HMI-Scenarios 44
Internet Technologies in Manufacturing - III -
4.2 Actor-oriented Perspective for managing the Information Architecture 46
4.2.1 Fundamentals of the Actors Approach 46
4.2.2 The Actors Approach in Internet-based Environments 48
4.2.3 The Actors Approach as a top-level Ontology 50
5 Implementation considerations of Internet-based Multi-Agent systems in operations 52
5.1 Application of Multi Agent Systems in Internet-based Operation Systems 52
5.1.1 Rationales for Internet-based Multi Agent Systems 52
5.1.2 Implementation Framework 58
5.2 Application of Multi-Agent-Systems in Internet-based Environments 62
5.2.1 Reconfiguration of the Production System 62
5.2.2 Production Planning and Control 64
6 Conclusion 69
References 70
Internet Technologies in Manufacturing - IV -
Table of Figures
Page
Figure 1: The Layer model of Internet-Technologies 7
Figure 2: Selected Services in the Internet 9
Figure 3: The Automation pyramid 11
Figure 4: Simatic Net of the Siemens AG 13
Figure 5: Transparent Ready von Schneider Electric SA 15
Figure 6: Control-Web von KUKA 16
Figure 7: Information Technology in Manufacturing 20
Figure 8: Consequences of the integration gap 22
Figure 9: Scenarios for the Integration 23
Figure 10: Generic Web-Services Architecture 31
Figure 11: Origins and Implementation of web-based Human Machine Interaction 46
Figure 12: Actors in Production Systems 47
Figure 13 Application Framework for MAS in Internet-based Production Concepts 61
Figure 14: Alternative Reconfiguration paths in different Environments 63
Figure 15: Distributed Production Planning and Control in the Actors approach 67
Internet Technologies in Manufacturing - 1 -
1 Introduction Currently we have to realize a major change in the technological basis of
manufacturing or even all production processes: The diffusion of new information
and communication technologies, especially Internet-Technologies, on the shop
floor. Applications of Internet-Technologies may be directly implemented on the
shop floor, e.g. in networking dislocated assembly lines, as well as in assisting
management processes, e.g. in production planning and control.
Both, formal and empirical studies have verified a significant increase in
productivity of manufacturing processes by intraorganizational applications of
modern information and communication technologies (Barua/Lee 2001, pp. 37).
Therefore, this change has a high influence on operations management. Early
applications of Internet-Technologies were limited to single, unconnected solutions
for distributed CAD-Systems or telecooperation. Now Internet-Technologies may
reach into automation and control level of every assembly line. Therefore, it is not
surprising that applications of Internet-Technologies in production processes on
the shop floor increase and those automation technology suppliers integrate
Internet-Technologies more and more into their products.
Currently, a comprehensive overview on the potentials and current state of
Internet-Technologies is missing. This paper tries to close this gap. We show the
path to Internet-based operations from a managerial perspective, figures out the
consequences, and offer some advice for its implementation.
In Section 2 we describe in detail the Internet and the underlying technologies.
One part explains in detail the specific Internet-Technologies in Manufacturing and
shows actual examples of industry solutions.
In Section 3 we discuss the current deficits in current ERP-Architectures and the
possible solutions deriving from the enhancements of modern Internet-
Technologies. The interconnection of the planning layer and the process control
layer is a serious problem, which can be solved by the usage of Web Service
Technologies.
The activation of the whole potentials of Internet-Technologies requires a
managerial approach. In Section 4 we describe two important aspects. On the one
hand, the activation of the full potentials of the employees is supported by web-
Internet Technologies in Manufacturing - 2 -
based Human Machine Interaction (webHMI). If the management conducts the
necessary steps to realize the potentials of webHMI, employees on the shop floor
can fulfill a broader spectrum of tasks. On the other hand, an adequate description
of the operations in terms of a semi-formal model ensures the interaction of
technical and managerial function in operations and prepares for the usage of
distributed artificial intelligence.
The operation management has to solve the problem of high complexity in
manufacturing deriving from the turbulence on the market. Practitioners and
Scientists discuss the application of multi-agent-systems (MAS) in planning and
reconfiguring the operations respectively the manufacturing processes. In Section
5 we present on the example of mass customization current approaches and show
an application framework for the application of MAS in operations.
2 Fundamentals of Internet-Technologies in Manufacturing
2.1 Fundamentals and Origins The origins of the Internet are studies of the US-Defense department that tried to
develop a fail-safe, decentralized architecture for information systems. The goal
was to found a network that remains operative in the case of a military attack
although some network elements or nodes fail or get lost. To reach that goal the
Arpanet was developed, which was mainly used for scientific purpose
(http://www.w3history.org/). This network was enhanced to the Internet later on.
Today Internet is the largest, worldwide computer network. It has been used
intensely since many years as an important basis for intraorganizational and
industry-wide information and communication processes (Heinzmann 2000, pp.
61; Picot/Reichwald/Wigand 1998, pp. 72, Mcbride 1997, pp. 58). The Internet is
not a uniform net, but a combination of decentralized data-networks. It represents
a worldwide alliance of several hundred thousand individual nets. These operate in
a stand-alone way, exchange, however, information under each other (Oenicke
1996, pp. 28; Zerdick et al. 1999, pp. 76ff.). Two features are characteristic for
Internet: the orientation at the client-server principle and the use of so-called
Internet-Technologies.
Internet Technologies in Manufacturing - 3 -
The Client-Server Principle defines, that an interaction can exist only between two
or several participants, at which
• one participant act as information and/or service provider (Server) and
• the other(s) act as information and/or service requester (Client).
A server can hold for example information in text form or offer more complex
services, such as data transfer, multimedia applications and data base mining.
Furthermore a client can assign the server to carry out specific tasks and/or
influence the behaviour of the server. Every participant can take over always the
role of a client or a server and these roles can change during the operation. With
that, a high flexibility is achieved and decentralized information storage is
supported.
The term of the Internet-Technologies is, however, indistinct and frequently employed in the literature, but admittedly not defined sufficiently. We follow the opinion from Zäpfel who defines "Technologies as knowledge of nature- and/or engineer-scientific interdependencies […], which serve or may serve as a method of implementation of user problems" (Zäpfel 1989, pp. 35). The term Internet-Technologies describes nothing but a family of open, standardized technologies (Buxmann 2001, pp. 434). They are suitable for exchanging structured data by means of package-oriented transmissions on heterogeneous platforms, in particular protocols, programming languages, hardware, and software. They may be used for global, interfirm, as well as intrafirm communication and information purposes.
The standards that are to be understood as Internet-Technologies in a narrower sense are listed at the Internet engineering task Force (ITEF - http://www.ietf.org/) and/or RFC repository (http://www.rfc-editor.org/rfcxx00.html) as well as with the World Wide Web Consortium (http://www.w3c.org/). An exact definition and/or a complete enumeration of all Internet-Technologies is however today due to the continuous foundation and redesign of standards and/or technologies not possible. The ITEF only lists at this time about 60 standards in the Internet protocol suite. We consider a systematization of the Internet-Technologies into following classes as expedient: Hardware, protocols and services.
Internet Technologies in Manufacturing - 4 -
2.1.1 Hardware
We distinguish the hardware in two groups: the terminal equipment and the
network infrastructure. Near the terminal equipment a considerable number of
heterogeneous systems developed in the last years (Zerdick et al. 1999, pp. 121
ff.). The emphasis is at this time is still on the networking of client computers. They
can be employed for fat clients, that are computers that store applications
themselves and carry out applications themselves, or thin clients, that are
computers that provide the applications carried out on a server. It is to be
observed, however, too, that systems that are not able to offer services
themselves on the basis of the Internet-Technologies, are networked with the aid
of "embedded devices". Embedded devices are used to expand systems that are
embedded into other systems by their functionality (Lee 1998b, pp. 25).
The importance of this approach is proofed by the fact that today more than 90 %
of all sold computers are embedded (Popp 2000, pp. 337 ff.). As a further trend
the increasing mobility of the systems is to be mentioned furthermore. Mobile
systems, for example personal digital assistants (PDAs) and mobile telephones,
are used frequently as terminal equipment for Internet-connections. An extreme
form, that is used particular military, also in the civilian airplane building, represent
the so-called wearable PCs. They are integrated into the clothing, set up a
connection to a net and supply their carriers with information continuously
(Rügge/Boronowsky/Herzog 2003, pp. 25 ff.).
The network infrastructure comprehends the communication technologies; also the
interfaces to the accessibility of the terminal equipment rank among the network
infrastructure. Communication technologies comprehend all technologies for the
transfer of signals with the help of a medium. The two main groups of the wire-
bound ones and the radio-controlled ones transfer are to be distinguished in this
case. With the wired transfer, enterprises today mainly employ twisted-pair cables
for the physical networking of the terminal equipment as a carrier medium. For
radio-controlled transfer radio waves are employed as a transportation technology.
Important technologies today are the wireless Local Area Network (WLAN) and the
from mobile telephones known Global System for Mobile Communication (GSM)
as well as the General Packet Radio Service (GPRS). In future, however, also the
Internet Technologies in Manufacturing - 5 -
use of Bluetooth as well as the new, comprehensive Universal Mobile
Telecommunications System's UMTS will expand. With all transfer technologies
the transfer of information occurs with the aid of the generation and conveyance
(easily) perceptible physical sizes, for example voltages (+5V, -5), luminous
intensity, frequencies and dephasing between two signals.
2.1.2 Protocols
The physical networking of the terminal equipment allows already the exchange of
electro-magnetic signals without sending information or specifying the intended
receiver of a signal in a net. To enable this, the commitment of standardized
protocols is necessary on both sides of a communication relationship (Alpar 1996,
pp. 26 f.). Protocols are norms and rules for the construction of combinations and
the exchange of data between communication partners (Tanenbaum 1997, pp.
44.). On the lowest tier, the networking layer, are today mainly employed the
Ethernet standard and to a small extent (< 20 % in office environments) the token
ring standard (Furrer 2003, pp. 57 ff.). The protocol used as a basis for the Internet
is however the Internet-protocol (IP). It controls the connection of all shared
participants with the aid of so-called IP-addresses (Douglas 2000). These are
twelve-digit numbers which allow a unique identification of the (mechanical)
communication partners (Alpar 1996, pp. 28 ff.; Marinescu 2002, pp. 226 ff.).
Furthermore the information to be transmitted into packets is bundled,
characterized with the addresses of the sender as well as the receiver, and
dispatched over the network. The IP controls thus the network layer of the
communication. A convenient transfer or protection of the data transfer is not
supported at this layer. Of special importance with the Internet-Technologies are
therefore the protocols of the transport layer that control the transportation of the
packets between client and server (Badach/Hoffmann 2000, pp. 46 f.). Particularly
known is the for the first time in 1974 published by Cerf/Kahn control transmission
Protocol (TCP) raised to the RFC 793 standard in September 1981(ftp://ftp.rfc-
editor.org/in-notes/rfc793.txt). The TCP allows a deterministic transfer of dates. It
is guaranteed that all sent packets reach the receiver. Through the complex
networking of the Internet and/or the high number at knots a loss of individual
packets can occur during the transfer process. The TCP guarantees the complete
Internet Technologies in Manufacturing - 6 -
transfer of dates by checking the incoming packets. An additional dispatch of lost
packets is initiated if required. This procedure determines that the data do not
arrive urgently in the initially intended and/or sent sequence at the receiver. Since
for program files or documents the complete transfer of data is necessary to
enable the processing of the files, this procedure is advantageous. If the
transmitted dates are to be presented or used during the transfer, then the
described procedure is not applicable. This is true with video or audio streams. In
this case another protocol is to be used, for example the User Datagram Protocol
(UDP, ftp://ftp.rfc-editor.org/in-notes/rfc768.txt, see Marinescu 2002, pp. 249 ff.;
and Furrer 2003, pp. 97 ff.). This protocol was created especially for the transfer of
dates which have to arrive in determined sequence at the receiver. This procedure
is employed for example during the transfer of values in industrial systems. Further
transport protocols that serve as substitute for TCP and/or UDP were developed
for the proprietary conveyance of commercial multimedia formats, for example for
QuickTime or RealMedia. The transportation of data packets between the terminal
equipment in the Internet does not allow providing the dedicated information or
communication services yet. For that a further layer of protocols is necessary.
That application layer contains the so-called application protocols
(Badach/Hoffmann 2000, pp. 47 f.; Schnell 2003, pp. 17 f.). These are for example
the transfer Hypertext Protocol (HTTP, ftp://ftp.rfc-editor.org/in-notes/rfc2616.txt)
that controls the exchange of structured data in particular in the World Wide Web,
The file transfer Protocol (FTP, ftp://ftp.rfc-editor.org/in-notes/rfc959.txt) for the
transfer of files, the Simple Transfer Mail Protocol (SMTP, ftp://ftp.rfc-editor.org/in-
notes/rfc821.txt) for the delivery of electronic mail and the Telnet (ftp://ftp.rfc-
editor.org/in-notes/rfc854.txt) for the use of remote resources and/or the Remote
login. Figure 2 summarizes the presented protocols.
Internet Technologies in Manufacturing - 7 -
Data Link Layere.g. Ethernet, Token Ring
Network Layere.g. Internet-Protokoll
Transport Layere.g. Transmission Control Protocol, User Datagram Protocol
Application Layere.g. Hypertext Transfer Protocol, File Transfer Protocol,
Simple Mail Transfer Protocol, Telnet
Source: Blecker (2005), p. 18.
Figure 1: The Layer model of Internet-Technologies
The packet oriented delivery of information standardized from the Internet
protocols has indeed the disadvantage that for example due to the necessary
codification from sender and receiver address, a comparably high administration
part is contained in the transmitted dates. At the same time this form of the
transfer allows using of almost all transmission systems and/or mediums and
presupposes no knowledge about the position of the communication partner. The
packets search with the aid of the enciphered sending and receiver IP address
their way through the Internet. This feature guarantees the high availability of the
entire net initially aimed in the Arpanet also in case of loss of individual net knots.
Furthermore using internationally standardized protocols in the network allows the
use of the hardware and software of different manufacturers, providers and
platforms without endangering the connectivity (Mertens/Faisst 1996, pp. 96.).
2.1.3 Services
On basis of the shown protocols suppliers implement different services in the
Internet between the servers and the terminal equipment and/or between the
communication partners (Alpar 1996, pp. 49 ff.; und AWK 1999, pp. 364 f.). For an
asynchronous communication the communication partners can resort for example
on the today widespread E-Mail (Lindemann 1996, pp. 7 f.;
Gluchowski/Gabriel/Charmoni 1997, pp. 304 f.; Middleton 1997). Furthermore, it is
possible to use discussion forums and bulletin board systems as news group
Internet Technologies in Manufacturing - 8 -
(Alpar 1996, pp. 56 ff). That allows enterprises to bridge chronological and spatial
distances of communication and to store the information for a longer time. If
information is supposed to be distributed by a central place onto several
customers, it is also possible to use broadcasting systems, for example mailing
lists, Listserv and channels. Information can therefore circulate and stored rapidly
in decentralized form.
A synchronous communication that bridges only spatial distances is allowed in
particular through the so-called instant messaging, for example the known 'Internet
Relay Chat' (IRC) like 'I Seek You' (ICQ), as well as video conferences. Instant
Messaging enables exclusively hard-copy communication, with conference
systems audio and video dates are transmitted simultaneous and processed
documents together (Alpar 1996, pp. 88 ff.). For the data transfer between
different computer systems a simple possibility is available on basis of the File
Transfer Protocol (FTP, see Alpar 1996, pp. 69 ff.; Mertens/Faisst 1996, pp. 96;
Reichwald et al. 1998, pp. 29.).
The use of remote resources and the sharing of dates and applications occur
mostly with the aid of one terminal of emulation and/or a remote login.
Communication partners dial themselves onto dislocated information systems and
can operate applications on external systems (Alpar 1996, pp. 74 ff.;
Mertens/Faisst 1996, pp. 96; Reichwald et al. 1998, pp. 29.). An application-
sharing is possible in particular with the aid of Java (Alpar 1996, pp. 109 ff.;
Wargitsch et al. 1996, pp. 6).
Java is a platform-independent programming environment of Sun Microsystems.
Applications programmed in Java can be carried out on almost all computers and
operating systems so that with the aid of the partly automated communications
interfaces of the Internet-Technologies and the corresponding applications a
cooperative use of decentralized Java-Applets is possible on one single system
(Martin 1996, pp. 39 f.; Schubert 1996; pp. 13 ff., Lipnack/Stamps 1997, pp. 183;
Sieber 1997, pp. 215). As the illustration 2 shows, the use of a great number of
different services is thus possible on basis of the Internet-Protocols.
Internet Technologies in Manufacturing - 9 -
Asynchronouscommunication
-Data-Transmission
Usage of remote
ressources/Sharing
• File Tranfer• Electronic Data
Interchange(EDI)
• World WideWeb (WWW)
• E-Mail• Discussion -
boards• Mailing lists• Newsgroups
(USENET)• Listserv• Channels
• Instant Massa-ging (ICQ, IRC)
• Web Phone• Video Conference
• Remote Login • Java-
applications• World Wide
Web (WWW)
Synchronouscommunication
Source: Blecker (1999a), pp. 62 (modified)
Figure 2: Selected Services in the Internet
The high number and heterogeneity of the services are stated frequent as
essential advantages of the Internet-Technologies (Blecker 1999a, pp. 62 ff.).
Furthermore protocols may be implemented due to the open character of Internet
and/or the Internet-Technologies without problems, like e.g. new services in
decentralized form (Picot/Reichwald/Wigand 1998, pp. 165). Software
development based on TCP/IP and/or the use of Java intra- and
interorganizational systems is today common for workflow management systems
(Wargitsch et al. 1996, pp. 11 ff.) and also distributed systems of the production
planning and control.
The Internet is a network that can be reached globally without essential limitations
and is therefore used also enterprise-externally. If Internet-Technologies are
applied enterprise-internal, we speak of an Intranet (Hawryszkiewycz 1997, pp.
212, und AWK 1999, pp. 366, Furrer 2003, pp. 34 f.). This is characterized by a
set of enterprise-intern participants, completely defined and separated from
outside. Members of the set of all participants are authorized only if they are
authenticated according to a corresponding authentication policy, e.g. to use
remote log-in. If also selected enterprise-external users are approved, for example
subcontractor, we speak of a so-called Extranet (Furrer 2003, pp. 35). In the
following all such systems that use Internet-Technologies in an essential extent
are meant however by Internet-based systems independently from the definition of
the user group and potential limitations of the entrance.
Internet Technologies in Manufacturing - 10 -
Furthermore, the Internet does not stand in the further process as
interorganizational network in the middle of the consideration. We concentrate on
the research of the intraorganizational contribution of the Internet-Technologies, in
particular in production. Already since the middle of the eighties, large parts of the
above outlined Internet-Technologies are used in the entrepreneurial practice. In
the production, since the middle of the nineties also the managerial and engineer-
scientific literature discusses intensely Internet-Technologies as an important
basis for strong information and communication systems in the production.
Therefore we will introduce selected application forms of the Internet-Technologies
in the production.
2.2 Application in Operations For the research of the network infrastructures in production environments a
hierarchical arrangement is to be carried out of the employed network and/or bus
systems on the different layers of the enterprise. An automation pyramid
represents this hierarchical arrangement most adequately (Pritschow/Reichle
2003, pp. 361, Jetter 2003, pp. 7). The engineer-scientific literature differentiates
between five to seven layers on which different bus systems are used (Scholz-
Reiter/Müller 1998, pp. 92 ff.; Schnell 2003, pp. 101 ff). For our economically
motivated research purposes an in such a way detailed differentiation is not
necessary. We concentrate therefore on the research of the three in our opinion
necessary layers, as shown in Figure 3: The Automation pyramid:
The uppermost layer is the enterprise layer. Here the enterprise planning occurs,
for example with ERP systems. In the office environment local area networks
(LAN) are used mainly; for example on the Basis of Ethernet and the TCP/IP-
Protocol Suite. This layer is cross-linked with the underneath production- and/or
process layer. On this layer for example Manufacturing Execution systems (MES)
are applied to provide a logical connection of the planning and the production
process layer. Furthermore, production-near dispositive tasks are processed by
the production control.
Internet Technologies in Manufacturing - 11 -
…
…
Machine control
Process control
planning
LAN / Industrial Ethernet / Process bus
LAN (TCP/IP)
Industrial Ethernet / fieldbus / SA-Bus
Per-sonal
...
MaWi
Logistik
PPSCon-
trolling z.B.ERP
Enterprise layer
Produciton/process layer
Field layer…
…
Machine control
Process control
planning
LAN / Industrial Ethernet / Process bus
LAN (TCP/IP)
Industrial Ethernet / fieldbus / SA-Bus
Per-sonal
...
MaWi
Logistik
PPSCon-
trolling z.B.ERP
Enterprise layer
Produciton/process layer
Field layer
Source: Blecker (2005), p.25
Figure 3: The Automation pyramid
Control centres are implemented hear. Industrial field bus systems (Process
busses) are employed as network infrastructure. From a technical viewpoint also
Ethernet-networks and/or the local area networks of the office environments are
purposeful on the production /process control level (Schnell 2003, pp. 106). Lately,
Internet-Technologies are implemented on the basis of the Industrial Ethernet. The
machines and plants serve on the lowest layer, the field level, respectively a
detailed viewpoint the individual sensors and actuators. Unlike the engineer-
scientific literature (Scholz-Reiter/Müller 1998, pp. 92 f) we do not differentiate here
a dedicated operation- and a cell layer on which for example the data collection
occurs. Contrariwise, we include these elements to the field level. The real-time
equipment on the field level are cross-linked frequent with the aid of field buses,
for example the different variants of ProfiBus (Schnell 2003, pp. 106 f.). Field
buses are a substitute for the individual wiring of sensors and actuators f and offer
a continuous communication infrastructure in the field level (Scholtz-Reiter/Müller
1998, pp. 104).
As a comprehensive term for the networks used on the process layer, following the local area networks of the office environment, is Field Area Network (FAN). Requirements for the FAN are in particular the real-time ability, a high transmission speed, a high reliability and the electro-magnetic compatibility (Duelen/Scholz-Reiter/Zanstrow 1995, pp. 16 ff.; Schnell 2003, pp. 102 f). The
Internet Technologies in Manufacturing - 12 -
individual layers of the automation pyramid are to be cross-linked. If on the individual layers heterogeneous network infrastructures are employed, this however cannot be done directly, but only with the aid of gateways (Schnell 2003, pp. 84 f).
Yet, field buses as a traditional, but competing network technology are still dominating in production processes, e.g. the ProfiBus concept of Siemens. In the future, Internet-based FAN will complement or even replace field buses. Since 1985, industrial firms have utilized Ethernet on the shop floor. Due to new standards, Industrial Ethernet reduces the technological limits that have existed up to now to the applicability of Internet-based FAN or even the replacement of field buses. Industrial Ethernet is based on the relevant international standards (e.g. IEEE 802.3). It is adjusted to the specific environmental conditions, for example regarding electromagnetic compatibility, shaking, moisture, and chemical resistance (Siemens 1999, pp. 20). In some sectors Ethernet and Industrial Ethernet are already the de facto standards, e.g. in the automotive industry, process industry and in plant engineering.
The technological improvement of Industrial Ethernet and/or Internet-Technologies in general does not necessarily enable a total replacement of field buses. On the one hand, some applications or existing machinery still need FAN based on field buses. On the other hand, field buses such as ProfiBus evolve towards a convergent, interconnective infrastructure, e.g. as in ProfiNet. Hence, even where Ethernet cannot replace field buses, Internet-Technologies connect the different assembly lines together and transfer detailed data from the shop floor to the office et vice versa. Consequently, a comprehensive application of Internet-based FAN enables the expansion of existing Intranets in office automation to all production processes, especially manufacturing. Enabling technologies, such as Web Services, Active Technologies, and Industrial Frameworks (based on .NET or Sun ONE), will support intelligent manufacturing technologies and a homogeneous network from office to manufacturing. These platforms have an enormous potential to reduce (transaction) costs within the production system (Blecker 2003a, pp. 39). Therefore, Internet-Technologies become a ubiquitous network respectively an omni-present information infrastructure in the complete industrial firm.
The development of the protocols supports the incremental use of the Internet-Technologies in the production. The safe data communication required for the field layer in case of which the sequence of the incoming packets is to be assured with the aid of TCP. This procedure is implemented based on the public Internet standard ISO transportation services (ftp://ftp.rfc-editor.org/in-notes/rfc1006.txt).
Internet Technologies in Manufacturing - 13 -
Siemens propagates a communications network for the automatic control which allows not only a networking within the production, but also a networking from the production with the office environment up to the accessibility of the machines and plants on the Internet on this basis of SIMATIC NET (Schnell 2003, pp. 239). This approach outlined should both guarantee the continuity of the industrial communication networks in an enterprise as also provide possibilities for the teleservice and control of the machines and plants. Siemens and further providers strive, however, to keep on being able to employ the existing facilities without modifications too. The approach of the ProfiNet was developed for this purpose on basis of the ProfiBus-approach (Profibus International 2003a, pp. 2 ff., Profibus International 2003b, pp. 5 ff). It is Ethernet-based, component oriented automation concept (Furrer 2003, pp. 201 ff). Furthermore, machines and plants become considered as (intelligent) components that consist of mechanics, electronics and software in each case and that are to be connected via standardized interfaces as a unit at an Ethernet-based network.
Source: http://www.siemens.de/
Figure 4: Simatic Net of the Siemens AG
Under the keyword of the interface for Distributed Automation (IDA) Siemens
introduced a further approach for net infrastructures on the basis of Internet-
Technologies in the year 2000 on the Hanover fair (Buchwitz 2001, pp. 60f.;
Buchwitz 2002, pp. 33f.; Jetter 2003.; Furrer 2003, pp. 197ff.). A hierarchy-free
network on the field level is aimed with IDA. With the aid of Ethernet and TCP/IP
Internet Technologies in Manufacturing - 14 -
are cross-linked both the automation technologies under each other, as also the
systems of the office environments, a potential Intranet as well as where
appropriate even with Internet (Schnell 2003, pp. 218ff.). The entire network is
supposed to allow in this case problem solutions in the sense of the distributed
(artificial) intelligence (Kirn 2002, pp. 54 ff). In spite of its decentralized
organisational structure as a uniform unit it enables at the same time an upright
integration in the sense of the Enterprise Application integration (EAI, Ließmann
2001, pp. 180f. Kaib 2002). The access and/or service are performed with the aid
of Web servers in the machines and facilities (Plagemann 2002, pp. 30ff.). These
are implemented with the aid of embedded systems where appropriate. In this
case machines and plants are mapped up to actuators and sensors with the aid of
individual IP addresses. The possibility to access the machines and facilities with
the aid of web browsers over the Internet or the Intranet is enabled by the
individual IP addresses. At the same time those machines and facilities can be
configured in a diagnosed and/or maintained over the network (Abadie 2001, pp.
60).
Particularly promising is the approach of the worldwide most often employed standard Modbus TCP/IP of Schneider Electric SA (Volz 2003, pp. 34 ff). This approach is based also on the commitment of Ethernet and TCP/IP in the automation technology. Modbus TCP/IP uses an own, sticky defined port. It is supposed to be introduced from the regulation authorities (IETF) of Internet as official standard for Internet-Technologies. This would mean that in all worldwide relevant operating systems a protocol is applied automatically in future, that was developed for automation technologies of industrial processes (Schnell 2003, pp. 224). With that it would be possible to cross-link every computer with networks in the production. This enables that the last step to the convergence of office and production networks takes place. A further essential advantage arrived through the fusion of the IDA group and the Modbus Organization to a common group in the October 2003. It is therefore to assume in future hierarchy-slack, in decentralized form organized networks on the field level become realizable. Schneider Electric SA presents commercial solutions under the denotation "Transparent Factory" and/or "Transparent Ready". How the Figure 5 shows, with the engaged network topology Ethernet becomes not only on the Enterprise- and the link layer, but is employed also on the field level.
Internet Technologies in Manufacturing - 15 -
Source: Schnell (2003), pp. 227
Figure 5: Transparent Ready von Schneider Electric SA
In order to use the different Internet-Technology approaches in the production,
Internet-Technologies are enhanced for example in pilot systems for the
manufacturing. An example is the Control Web of sealing machine KUKA GmbH,
Bosch GmbH, Trumpf GmbH & Co KG and further enterprises of the automatic
control (Birkle 2001, pp. 36 ff.; http://www.kuka-control-web.de/ checked
01.06.2004). As the Figure 6 shows, the essential features of this approach are
the continuous use of Ethernet in the field level, the use of personal computers for
the control and the integration of web servers on the basis of embedded systems
into the automation systems (Ebert/Klüger 2003, pp. 23 f). For the communication
and/or the service of the system web browsers are used. First complete plants for
the body making in the automotive industry consistently employing Internet-
Technologies are to be implemented until to the year 2005 (Ebert/Klüger 2003, pp.
25).
Internet Technologies in Manufacturing - 16 -
Source: http://www.kuka-control-web.de/
Figure 6: Control-Web von KUKA
The technological adaptation of the Ethernet-standard onto industrial
environmental conditions and the commitment of Internet-Technologies in the
production do not mean however that field bus systems are substituted completely
(Blecker 2003f, pp. 140). On the one hand field bus systems and their particular
qualities keep on being needed for the networking of existing production systems
or because of the presence of specific requirements and/or application conditions
(Jetter 2003). On the other hand the field bus systems are forced by the producers
of the automatic control increasingly in the direction of a convergent,
interconnectivity network infrastructure, for example ProfiBus to ProfiNet of
Siemens. Therefore, Ethernet-based Networks can not substitute the field bus
systems (complete). Internet-Technologies are especially useful for the networking
from production lines under each other as well as for the data transfer from the
technical systems in the production to the enterprise systems in the administration
et vice versa. Also the numerous initiatives for the implementation of the Internet-
Technologies in automation show this. The producers of the automation facilities
have to pay attention, that in spite of the concurrent solutions to the commitment of
Internet-Technologies in the production as Profi-bus and IDA are not become
Internet Technologies in Manufacturing - 17 -
again incompatible, proprietary systems on the field level.
In sum, Internet-based Field Area Networks (FAN) may connect office information systems with the automation and control level of every assembly line. It is not surprising that applications of Internet-Technologies in production processes increase and that many automation technology suppliers combine Internet-Technologies with their products. This leads to a convergence of the traditional production systems and Internet-Technologies (Blecker 2001, pp. 19). It explicates the unification of technologies with different features to a homogeneous service bundle, which enables the revision of traditional Production Concepts or even the development of new Production Concepts (Blecker 2005).
2.3 Selected Services and Languages Ethernet Based networks and the application of the TCP/IP Protocol Suite in the
automatic control strive on the one hand for an integration of the different layers of
the automation pyramid. On the other hand they create the condition for usage
both from the Internet known services as well as new services in the field layer.
For the preparation of the information to be transmitted and/or to be represented
the application of appropriate languages is however necessary (Schnell 2003, pp.
361).
In Internet, in particular with the today most important service, the World Wide
Web (WWW), clear-text languages as the HyperText Markup Language (HTML)
are mainly employed. In the same way as in Internet it is also in the automatic
control possible to provide help systems and manuals to the employees in the
production with the aid of central web servers in the local network and/or individual
web servers in the machines and facilities (Pritschow/Reichle 2003, pp. 362).
Order documents, work schedules, bills of material and assembly instructions are
to be provided also in this way. In this case it is unimportant on which server or in
which database the linked information is stored (AWK 1999b, pp. 381). It is
furthermore useful that multimedia contents as pictures, animation and videos are
simply to be linked. Furthermore HTML pages are useful in the machines and
facilities during the poll of simple machine dates and/or the manual delivery of
parameters. Those information sources can be used form all levels in the
enterprise and provide therefore the basis for a friction-free informational
interaction (Jetter 2003, pp. 14).
Internet Technologies in Manufacturing - 18 -
An essential problem of HTML is however that it was mainly created for the
representation and/or preparation of information, which mean it describes the
appearance of a document or an information, however not the content-related
structure (Buxmann et al. 1999). Although today web servers provide HTML-pages
in many automation systems complex applications require an automated
processing and/or interpretation of information. With HTML principally this cannot
be realized. The meta-language eXtended Markup Language (XML) allows those
the content-oriented annotation of data. XML is as a subset of the Standardized
General Mark-up Language (SGML) employed for publications. Due to the
independence of the XML documents from different fields of application, particular
applications can be developed, for example for the fields of mathematics,
chemistry and industrial management (Fischer 2000, pp. 425). XML is anyway to
be encoded and sent with the aid of web servers and web browsers and just the
same way as with HTML-based pages.
The most important advantage of XML and the description languages based on it
is that due to the semantic qualification data a human and a mechanical
interpretation and/or processing of information becomes possible. This processing
is independent from the employed data formats and the applications. Generators
convert for this purpose the existing local data structures into the meta-language.
The contents of a document are characterized with the aid of the definition of
distinction elements. That allows a structured data exchange between different
application systems. In addition to the human interpretation of the information with
HTML a mechanical interpretation is to be implemented thus, for example for bills
of material, work schedules, schedules, and capacity plans. With that a central
demand of some authors is accomplished. They request to provide multimedia,
product and process dates that may be interpreted by machines and human in the
decentralized production structures, in order to create a new quality of the
production management (Fischer 2000, pp. 423).
Furthermore, it is possible to reduce the problems of the data conversion as well
as to enhance the quality of the data communication between heterogeneous
systems of different enterprises by the use of XML. So for example XML
databases in the manufacturing layer make available processed machine dates
from the field level as HTML for web browsers, as Wireless Markup Language
Internet Technologies in Manufacturing - 19 -
(WML) for mobile terminal equipment or in the form of a PDF- and/or postscript
file. Also a requirement raised already since decades at the CAD/CAM integration
would be accomplished. This trend is supported by the establishment of standards
such as factoryXML. With factoryXML a dedicated approach based on XML is
available, that enables the connection of data from the shop floor with the ERP-
Systems (Homburg 2004, pp. 43 f.; http://www.factoryxml.com/sites/factoryxml.htm
checked 01.06.2004). This possibility did not exist up to now both due to the
heterogeneous standards of the data communication in the different layers of the
automation pyramid and due to heterogeneous description and/or representation
of the dates.
Services that up to now indeed were not used in the production are to be
implemented with the aid of Internet-based Field Area networks. For example the
use of automatically generated emails through machines and plants is expedient in
specific scenarios. Messages about machine states, part numbers, temperatures
or disturbances are to be sent between dislocated automation systems at
receivers on the enterprise layer or even at receivers outside of the enterprise
(Renner 2001, pp. 46 f). A pilot project was implemented already some years
before at the Varta AG in one for humans not compatible work environment during
the battery manufacturing (AWK 1999a, pp. 373). Employees outside of the
production line are informed over machine states and troubles for example by
email and may intervene and control with the aid of web browsers or a Remote
login's on basis of Telnet. The Figure 7 shows an example of Siemens which
corresponds basically to the solution implemented at Varta.
Furthermore, Internet-based Field Area networks are not bound at cables as a
transmission medium. One of the main areas of application of the phone modules
for example of Nokia and Siemens is the networking of machines and plants. Until
the year 2006 already 100 million Machine-to-Machine couplings are supposed to
be installed to with the aid of phone modules in Europe (Gillies 2003, pp. 29.). But
also WLAN-modules are used increasingly for the accessibility of existing network
infrastructures of the production (Siemens 2000, pp. 18 f., Kröner/Montague 2001,
pp. 26ff).
Internet Technologies in Manufacturing - 20 -
Source: Siemens (2000), pp. 17
Figure 7: Information Technology in Manufacturing
With support of Mobile terminal equipment, for example PDAs or Tablet PC's,
employees are able to visualize, collect and/or controlling spatially unbound data
of the machines and facilities flexibly. Furthermore, first preproduction models for
the support of assembly workers are developed already. They enable the use of
context-sensitively provided information, for example assembly drawings, on the
mobile terminal equipment (Gausemeier/Grafe/Matysczok 2003, pp. 11f).
However, during the assessment of the impacts of Internet-Technologies we also have to consider the potential risks (Furrer 2003, pp. 247ff). The existing infrastructures can be an essential obstacle of a commitment in many cases. A temporary receipt of the field bus systems is necessary if investment protection requires the further use of specialized infrastructures. Technically this problem can be solved with gateways between the fieldbus-systems and the Internet-Technologies (Cena/Valenzano/Vitturi 2001, pp. 41). Big suppliers in the field of the automation technology offer corresponding solutions and Internet-suitable field bus systems (Siemens 2001). It is more problematic that the Internet-Protocol is considered in some cases from fundamental reasons crucially in production environments, since it often does not correspond to the high demands on the data transfer there. With the new version of the Internet Protocol (IPv6 AWK 1999b, 367ff. Blecker 2003f, pp. 147f und Furrer 2003, pp. 251ff). features are defined, which correspond also to the orders in production environments.
Internet Technologies in Manufacturing - 21 -
From that, only security aspects can be problematic with the usage of Internet-Technologies in manufacturing. The danger that important machines and plants are exposed to sabotage and espionage attacks for example through hacker, viruses and trojans exists. However, technical and/or organizational protection mechanisms already known from the office environment reduces the problems, e.g. cryptography, steganography, virus scanner, firewalls, and access controls (Baumann/Spobert 2001, pp. 173 f., Köbinger 2003, pp. 3).
3 Information System Architectures for modern Operation Systems
3.1 Manufacturing Execution Systems In the last years in industrial firms had great successes with the implementation of
enterprise resource planning systems (ERP) in the planning layer, the systems of
the process control layer and with the application automation techniques. Due to
heterogeneous standards or incompatible systems they are mainly not
interconnected up to now. The offered potentials to reach higher efficiency of the
industrial business processes are not used optimally. Companies therefore use
Manufacturing Execution system's (MES) for a stronger integration of the
unconnected systems.
With the advances of Internet-Technologies new production systems and concepts
are possible. These are based on a direct networking of the machines and plants
as well as a coupling of the information systems in production with all other
information systems in the enterprise. With this development, the Requirements,
general conditions and demands on the integration of the managerial layer and the
process control level change.
3.1.1 Integration Gap between Planning Layer and Process Control Layer
The use of dislocated systems in the managerial as well as in the process control
layer leads to insufficient or completely missing availability of real-time data from
the production system in the managerial layer. This triggers higher cycle times of
planning back to the control layer. The production schedules automatically
decouple from the real states of the production system and the reaction times of
the planning level rises. The requirements at industrial firms, as lower error ratios,
Internet Technologies in Manufacturing - 22 -
small cycle times and high capacity utilization, are thus not fulfilled in the required
scale.
Source: Blecker/Graf (2003), p. 29.
Figure 8: Consequences of the integration gap
Therefore an essential goal is to achieve a high transparency of the processes on
the planning as well as on the process control layer (Dilts/Boyd/Whorms 1993 p.
80f). This is to be achieved with the aid of a (data processing and organizational)
integration of the both layers. Following tasks are necessary due to the barriers
existing between these layers: (www.mesa.org)
• check the production processes
• compile, filter and process the data from the process layer
• visualize the current one production status
• support the deviation analyses in the ERP-system
• delivery from planning information to the process control layer
MES are the most widely used tools for managing and fulfilling these tasks. MES
cross-link the different information and automation systems and couple the
application systems of the planning layer and the process control layer. MES
guarantee a continuous, bidirectional information and communication flow from the
planning layer into the process control layer et vice versa. This means that the
Internet Technologies in Manufacturing - 23 -
ERP-systems is not coupled directly with the process control, but gets the data
about the process control and the automation technology From the MES.
The main task of the MES is therefore the coupling of the plan and process control layer in industrial firms. However, important modifications which perform a considerable influence on the actual requirements occur in last time through the presented application of Internet-Technologies in manufacturing (Blecker 2003). These modifications lead to three alternative Scenarios of the integration of the planning and the process control layer, which we discuss in the following.
3.1.2 Vertical Integration of the Planning Layer and the Process control
layer
Scenario 1: Utilization of MES
In the first scenario the integration of the planning layer and process control layer
is implemented with the aid of MES. Although the commitment of the Internet-
Technologies allows a direct communication of the different systems, these
systems remain here unconnected. A MES realizes the integration. This scenario
has from that the advantage, that already existing, non-IP based systems can be
merged more easily and so that a protection is achieved for already made
investments.
(Control, data collection and -distribution, ...)
Use of MES Direct Coupling Web Services
Planning Layer
MES(Monitoring, Data Collection
Data Distribution, ...)
Process Control
Planning Planning
Dire
ctor
y
SOAP
, XM
LInternet-Technolo-
gies
(Control, data collection and -distribution, ...)
Process Control Process Control
Source: Blecker/Graf (2003), p. 30.
Figure 9: Scenarios for the Integration
Internet Technologies in Manufacturing - 24 -
It is expedient however in many cases to design the MES at least Internet-
enhanced, to ensure a to a large extent friction-free integration with the newer
systems and to allow a migration to homogenous system structures on a long-term
horizon. Furthermore, many providers advance their MES to so-called "Industrial
Frameworks" which guarantee a modular use of the MES-components as
integration platforms. The use of Internet-Technologies both with the Industrial
Frameworks and with the planning and process control systems is in this case
possible, conceptual however not imperative.
Scenario 2: Direct coupling of planning layer and process control layer
Here a direct linking of the information systems is supposed. The application of Internet-Technologies in the production allows fully integrated information systems. The central motivation for the establishment of MES, the separation of the planning layer and process control layer prevailing up to now (data processing and/or organizational), is dropped thus. The systems of the planning layer are linked for this purpose directly with those of the process control layer to enable an overall, bidirectional communication of all relevant systems. The data storage and the data flow control are covered in this case through the ERP-system and/or the systems of the process control level.
This hypothesis is supported also from a study of the Gartner group (Miklovic 1999), that predict the era of application of the MES shrinking clearly since their functions are not necessary anymore and/or are taken on by the ERP- as well as the control automation systems. This scenario however is technologically in many cases only realizable with a complete reinvestment of information systems on the planning layer and process control layer.
Scenario 3: Internet-Technologies as an Integration Instrument (Web Services)
In this scenario we assume that the MES is substituted through several, partially independent authorities. The integration platform here is “web services” that on the one hand can deliver the tasks of the visualization, filtering and workmanship of the dates. On the other hand they provide, also a platform for the communication of the distributed systems. This requires that both the planning systems as well as the process control layer dispose of the necessary technologies. Examples are the “.net” architecture of Microsoft or "Sun ONE". No (acting) participant in the communication process is created by that unlike the commitment of a (centralistic) MES between the two layers, but a common communication basis is set up for the necessary communication. A Directory service allows discovering distributed services and information in the up to now separate layers. With the aid of
Internet Technologies in Manufacturing - 25 -
appropriate languages and protocols, for example the Simple Object Access Protocol (SOAP) and Extensible Markup Language (XML) a service oriented architecture for manufacturing can be set up. This architecture is described in the chapter 3.2. The use of the common communication basis for the integration leads in comparison with MES to a smaller complexity of the integration and to decentralized infrastructures. Existing systems of the planning layer and process control layer keep are used as legacy-systems.
The integration of the planning layer and process control layer with the aid of Internet-Technologies is at this time not developed completely yet. Deficits of current Web services are particularly the distributed transaction accuracy, complex workflow automation and the messaging. In connection with Java 2 Enterprise Edition (J2EE) Web services are already used today for the integration of almost all company internal information systems in the sense of the enterprise application integration (EAI) (Voßhenrich 2002). The states of the machines and facilities as real-time data become permanently available in the information systems and can be employed for the planning and controlling of the processes.
Due to the frequently predicted high importance of Web service's for the EAI an enlargement or even substitution of the up to now employed MES are to be presumed also for the integration of the planning layer and process control layer (Voßhenrich, O. 2002, Füricht et al. 2002). These developments are supported by current advancements in the Web-Services field. The upcoming concepts of service oriented architectures seem to provide all necessary technologies to handle the complex information flows between planning layer and process control layer as suggested in scenario 3.
3.2 Service Oriented Architectures (SOA) 3.2.1 Technological Deficits in current Information System Architectures for
Enterprise Resource Planning (ERP)
The impossible foresight on the theoretically possible changes of the production
system hinders an anticipation of those changes in the information systems’
design. To react agile on the changes in the production environments, information
systems have to allow a fast adoption of the systems structure and the methods.
Traditional software development and also software adaptation follows specific
process models like the V-Model or the waterfall-model. Forming a conceptual
model on the basis of a detailed analysis of the domain is in turbulent
manufacturing environments to costly:
Internet Technologies in Manufacturing - 26 -
• The e.g. in ARIS necessary detailed knowledge about the separate process
steps is in non-stable structures (in some cases) not available.
• The development of traditional process models requires that information
system experts and the users of the information system communicate and
agree on a certain description of the domain. This often requires several
iterations and meetings to avoid misunderstandings e.g. because of
different terminologies.
In modern production environments, the pragmatic of the manufacturing processes
varies more often in shorter cycles. Therefore, the modelling techniques for
information systems are not applicable, because they are assuming a stable
pragmatic for longer periods of time. They build up restrictions in manufacturing
that would not allow transforming the actual production program in certain
directions. Due to the time consumption of traditional modelling, it is not possible
to model every new process in a new situation.
An adequate information system design requires an approach, which enables self-
organized changes of information flows without having to change the applications
(or strictly speaking the code by a programmer). Clearly, it is not possible to set up
information infrastructures that completely provide this requirement. Firms should
therefore strive to set up information system architectures that require re-
programming applications and/or interfaces only in exceptional cases. Information
Systems have to meet the following criteria to meet this requirement:
• Every unit has its decentralized information system providing a universal
information interface. We assume that these interfaces base on Web
Service technologies. Although in several technical aspects there are more
elegant approaches e.g. for procedure calls, (CORBA; JINI), SOAP seems
to have become the choice of the industry.
• The decentralized information systems require sufficient computational
power and have to allow an altering of all methods, objects and parameters
they are representing. This means they have to make available all
functions, such as the whole machine control or data manipulation.
• Workers without detailed knowledge about the information system have to
be able to use and alter it. This requires that appropriate user interfaces are
Internet Technologies in Manufacturing - 27 -
created as well as the information is structured and presented according to
the user’s knowledge.
In an operation system supporting these requirements, the actors are able to
communicate and exchange data with each other without having to meet. The
necessary information exchange tasks are complex. Actors exchange complex
data concerning the production processes like construction plans and order
details. The information systems have to provide assistance features in these
interactions to ensure a proper logging of the tasks. There are various concepts for
autonomous information technological software units to provide these features of
workflow management.
The resulting ubiquitous information infrastructure differs fundamentally from
current information system approaches that are based on centralistic systems for
the execution of business processes. The composition of operational processes in
combination with the necessary information processes cannot be implemented
based on current ERP-structures. This does not imply that it is necessary to
replace current ERP-Structures. Contrariwise, it is necessary to separate the ERP-
world from the information systems in the operations and set up a loose
information exchange. There are several rationales for this:
• Legacy systems will not provide extended adaptability in the future. That is
on the one hand justified by the complexity of those systems and, on the
other hand by the different business economic and legal requirements for
those systems. ERP Systems are designed to provide solid factoring
infrastructures, aggregated cost information, and long term planning data.
• ERP-Systems enhanced with capable interfaces are based on web services
and other Internet-Technology standards allow connecting to the interaction
infrastructure in operation systems. An example is the SAP-Netweaver
infrastructure.
• An ERP-System provides the necessary infrastructure for aggregating the
enormous data quantities. The interfaces of ERP-Systems can be used to
push the information from the operation system into the ERP-System.
• ERP-systems become too complex if they integrate too many aspects of the
information infrastructure (Martin/Mauterer/Gemünden 2003,pp. 115).
Internet Technologies in Manufacturing - 28 -
Therefore, the data necessary for the ERP-Layer has to be aggregated for usage
in ERP Systems. Lüder et al. show an approach where the coordination between
the process control in the operation system and the ERP System is done by a
Multi Agent System (Lüder 2004, p. 202). As shown in (Blecker/Graf, p. 38),
Manufacturing Execution Systems could be replaced by an extended, Web-
Service based infrastructure that is inherently decentralized.
3.2.2 Service-oriented Architecture as a Solution to ERP-Deficits
The integration of the planning and process control layer is a complex application
integration problem. Also in modern enterprises a large number of information
systems exist, which are still isles and are only loosely interconnected (Sharif et al.
2004, p. 165). Within the last years, the requirements of application integration
have grown constantly. On the one hand, it is necessary to intensify the integration
of information systems, to get a higher speed of data exchange and to associate
up to now isolated data bases for the use in business intelligence and customer
relationship-management scenarios. Business intelligence means in general the
generation of information concerning the situation, capability and intentions of the
own as well as competing enterprises on the basis of a large amount of
unstructured data Hollich/Fricke 2003, p.83f.). Customer relationship
Management tries to gather the same information about the customers. Both
concepts need, for optimal implementation, a tight integration of all information
systems. On the other hand, to stay competitive it is necessary to arrange
integrated information flows. This means that the information systems in the
operation system are all interconnected, with ideally no redundant data storage
and manipulation. The failure of early CIM-Approaches with a very centralistic
integration of information systems has shown that only a at least partially
decentralized information architecture approach is necessary (Scheer 1994, p.28).
This has led to integration approaches, which try to interconnect the
heterogeneous information systems in the enterprise. These approaches and
applications are summarized under Enterprise Application Integration (EAI). The
need for integration has generated a huge market for EAI-solutions. The
disadvantage of EAI results from the again centralistic approach. One information
system is connected to all existing information systems in the enterprise. This
Internet Technologies in Manufacturing - 29 -
central server fulfills the necessary data transformation for the exchange. In
practice, the adaptation of this central integration point is very costly and has lead
to many errors in the integration. A main reason for the use of these EAI
approaches is the heterogeneity of interfaces and network technologies, especially
in manufacturing enterprises.
An alternative approach to reach the goal of EAI is the so-called service-oriented
Architecture (SOA) (Dostal/Jeckle 2004, p. 53). This is principally no information –
technical approach. The SOA-Concept was developed in the early 90ies to allow a
decentralized information exchange between different information systems.
Technologically the concept has been implemented with CORBA. In the
beginnings of the 21 century, the approach was adapted on the base of Internet-
Technologies. A Service in the Internet-based SOA are information systems, that
are able to give on a request a answer, like the supply of information on web
servers. The difference is that in the case of SOA information systems interact. For
example, a planning system, that is implemented according these ideas, is able to
deliver all information in itself to requestors. For example, an inventory system
could then “ask” the planning system for the planned capacities in the next period.
The service oriented architecture foots on 4 principles:
• Distribution. The logic of application and information systems is distributed
over different computers, separated from each other and arranged
according the needs of the organization.
• Loose Coupling. Information Systems can exchange a wide array of
information In SOA, information Systems are distributed, which means they
can stay productive independent from the stat of other, interconnected
information systems.
• Standards. SOA-Approaches foot on the use of open Standards. Today
these standards are based on Internet-Technologies, whereas the
beginnings of SOA the CORBA approach was dominating.
• Process-Orientation. The most important rationale for SOA is the possibility
of enterprise-wide process oriented flow of information between functionally
oriented information systems, without centralization.
Internet Technologies in Manufacturing - 30 -
The technology for the realization of those principles is the so-called web-services.
Web services consist of a set of universally agreed specifications including XML
(eXtensible markup Language), SOAP (Simple Object ACCESS Protocol, WSDL
(Web Services Description Language) and UDDI (Universal Description, Discovery
and Integration). Excellent technological overviews are given in (Ferris/Farrel
2003; Tsaligatidou/Pilioura 2002). The approach addresses the above mentioned
problem. Software components are modelled as services. Service providers
publish descriptions (WSDL) of the services that they support to one or more
registries (UDDI). A prospective service requester can query a registry to obtain
information for service implementations that meet a specified description. This is
clearly a great help in the case of a large-scale system, because it disseminates
information about the available components to those who would wish to use such
components in their software systems. In fact, the programmer is no longer
needed in the critical path, because services can be found and bound dynamically
and automatically by the software system. Through the possibility to implement
web service communications on the basis of HTTP, firewalls and other security
concepts can be (technically) better applied than by a remote procedure called
e.g. CORBA to ensure security. This is essential for the interorganizational
collaboration, especially in ad-hoc scenarios (Estrem 2004, p. 552).
Figure 10 shows the components of a Web-Service Architecture. The base
Technologies like XML, DTD and Schemas and the communication component
are discussed in Section one of this paper. Web service management is the
management of Web services through a set of management capabilities that
enable monitoring, controlling, and reporting of, service qualities and service
usage. Such service qualities include health qualities such as availability
(presence and number of service instances) and performance (e.g. access latency
and failure rates), and also accessibility (of endpoints). Facets of service usage
information that may be managed include frequency, duration, scope, functional
extent, and access authorization.
Internet Technologies in Manufacturing - 31 -
Source: http://www.w3.org/TR/ws-arch/
Figure 10: Generic Web-Services Architecture
The application and usage of Web-Services generally is an emerging field in
literature (Zhao/Cheng 2004). There are several advantages of Web-Services that
accelerate the adoption of the technology:
• Advantages with the transfer and the linking of information. Web Services
accelerate the speed and reduce the cost of integration with various internal
applications and systems.
• Vendor independent transparency. The technologies of Web Services freely
available and not vendor-specific.
• Simplicity of basic concepts. They also have the potential of reducing
programming skill requirements and improving (service) asset reuse, thanks
to its service-oriented structure based on open standards (Huang/Chung
2003, p. 16.)
• Support through the large information system vendors.
• Enabling of the Semantic Web.
For the optimal application of Web-Services, ideally an automated composition of
the distributed services is to be strived for (Sirin et al. 2004, Sp. 377). This
requires on the one hand semantic information at the web service description. On
the other hand, the automated service composition with web services extends the
SOA-concept and approaches the concepts in distributed artificial intelligence
Internet Technologies in Manufacturing - 32 -
(DAI). In the next section we discuss the technological advancements in this field.
A combination of Multi-Agent approaches and the SOA promises to be a suitable
way to realize at least partial self-organization of information systems, which is
already implemented for “smart houses” (Sirin et al. 2003). The same benefits
based on Internet-Technologies are possible in operations and manufacturing
(Hao/Shen/Wang 2004).
3.3 Internet-based Multi-Agent Systems (MAS) 3.3.1 Rationales for MAS – the example of Mass Customization
Multi-Agent Systems (MAS) have been discussed since 1985, when cooperation
among intelligent agents was at first proposed in computer science (Rosenschein,
1985). MAS are part of distributed artificial intelligence, such as cooperative
problem solving or blackboard systems. These approaches deal with a priori
known, distributed tasks that require intelligent problem solving behavior. The
difference of agent systems compared to other methods of distributed problem
solving is the bottom up approach (Kirn 2002). This means that autonomous
intelligent agents that have certain knowledge about their specific domain are
trying to reach their goals by cooperating with other intelligent, autonomous
agents. Autonomous agents themselves are defined as systems that are situated
in and are a part of an environment, as well as sense that environment acts on it
over time in pursuit of its own agenda (Franklin/Graesser 1997).
The advantage of MAS is the possibility to solve partial problems without having to
consider the general problem. Intelligent agents know about their specific domain
and try to obtain the necessary information or resources to solve the actual
problem. The agents have to cooperate with other agents, which can be organized
in terms of negotiation, bidding or opportunistic behavior. In several research
projects the usefulness of MAS in realistic commercial application scenarios has
been investigated (DFG 2002). Production is one important domain for MAS.
Several MAS-based solutions have been developed for complex problems in
manufacturing. MAS are analyzed for the machine control and the controlling of
manufacturing lines to get a more fault tolerant and more flexible
(Sundermeyer/Bussmann 2001). Production Management research utilizes MAS-
concepts mainly to enhance flexibility and robustness in production planning and
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control systems. Interorganizational approaches also try to apply the approach for
planning and control supply chains and business networks (Turowski 2002). Mass
customizers may use the intended features in different ways (Piller 2000).
MAS are more precise in planning, scheduling and reconfiguring production
processes (Corsten/Gössinger 1998), respectively the dependent information
systems, such as production planning and control. The often encountered
turbulence on the market requires adequate changes in the behavior of
manufacturing enterprises. One approach is to get a Mass Customizer. Mass
Customization aims at the production of individualized products nearly at mass
customization efficiency (Pine 1993). A characteristic of mass customization is the
direct interaction between customer and manufacturer during the configuration
process. Fast creation of new variants, as well as transparency for the customer is
the main requirement for a mass customizing enterprise. Conventional software
architectures are insufficient, if operations are closely interlocked, the goals of
local actors have to be synchronized with super ordinate objectives and
concurrently fast reactions on random unpredictable events are necessary for
successful acting (Kirn 2002). Because of the high requirements of mass
customization there has been much research in creating an adequate information
infrastructure. Therefore, we use these approaches to analyze the applicability of
MAS in Manufacturing.
Zipkin (2001) states the logistics, the process flexibility and the elicitation as
critical. In our view we have to especially consider process flexibility. Elicitation is
not in the scope of this paper, and logistics are only touched upon in internal
aspects. We are concentrating on production issues. Tseng/Lei/Su (1997)
formulate for mass customization production itself the following necessary
characteristics:
• Dynamic manufacturing requirements
• Flexible resources
• Postponement of product variety
• Product family architecture
• Flexible process routing
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These characteristics define the basic requirements for production in mass
customization. Indeed, the characteristics cause higher complexity to run, plan and
control than in traditional production systems (Tseng 1997). Production
management needs instruments to handle the complexity in the production
system. Information systems are an important issue when dealing with this task.
Many researchers argue that traditional ERP-systems cannot cope with highly
flexible, dynamic environments (Piller 2001). Therefore, more adequate
information system structures are necessary. MAS may be an approach to design
information systems that meet the requirements of production systems in mass
customizing companies. Different forms of mass customization exist in practice,
reaching from service individualization at the reseller (soft customization) to a full
customization of the product, which means that the mass customizer is actually a
variant producer (hard customization), but reaches a higher output e.g. by using
standardized modules (Piller 2001, Pine 1993). The soft-customization, which is
not involved with the production itself, is not a field for MAS, because the
production itself does not change and conventional information systems are
suitable in this case. MAS as a concept that is able to handle complexity by being
able to take into consideration much more parameters than monolithic software
systems is only useful if there is a large amount of complex information that has to
be processed. This is trivial, but the issue is to find the critical point for the
usefulness of MAS. Clearly, the hard customizer might reach that point. We are
not able to define the exact point, but we can state that there are scenarios when
MAS in of an advantage against traditional systems.
Mass customization often requires introduction of new variants and even to
remove variants to optimally meet customer requirements on the one hand and to
hold costs down on the other hand (Blecker et al., 2003). Therefore, the production
system has to quickly adapt to changes in the variant portfolio. Many variants are
manageable by the existing configuration of the production system. However, if
there are new variants with new parts or processes which are necessary, these
changes have to be introduced quickly. Furthermore, mass customizers have to be
able to react on customers' requirements that are out of range. MAS may also
speed up changes in the material flow system and the machinery by way of
reducing the efforts for implementing the changes in the information system. A
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MAS that controls the material flow system is able to automatically consider a
change in the capacity of a machine because it is considering the machine as an
autonomous resource that indicates its capacity by itself.
Although there is the ability to support the (re-)configuration of system elements
and variants for mass customization, the control of the entire production
environment is the most important field for MAS. With a defined number of variants
provided, there is much uncertainty in the production because of the random
demand for variants. Scheduling and routing in the production system is very
complex, because the dilemma between minimized lead times and maximized
machine utilization has to always be considered. Under stable conditions, a
standard ERP-system is able to optimize the ratio, but if there is a high grade of
uncertainty, standard production planning and control concepts are not able to
manage the complexity (Corsten/Gössinger 1998). Additionally, production
planning and control in mass customization has to be able to support dynamic
changes in production plans in very short intervals, so that the unsteady customer
orders may be produced at low costs. Even decentralized PPC approaches cannot
manage this, because rush orders require one to change the entire production
plan. MAS can recalculate the plan immediately and identify the best alternative.
3.3.2 Recent Results in applied research
The benefits of Internet-based MAS for mass customization is analyzed in several
research projects. We can separate existing concepts in interorganizational
approaches, which use MAS for the planning in supply chains for mass
customizers. Other approaches concentrate on the scheduling or technical
aspects in machines, or for use in reconfiguration tasks. The last group builds a
full framework for the entire production environment.
Interorganizational focus Turowski (2002) uses agents for so-called macro-processes in interorganizational
mass customization scenarios. He suggests the use of an Internet-based
approach for EDI to allow automated supply processes. Agents negotiate terms of
shipment, prices based on actions within the mass customization company. The
approach shows the possibility to implement intercompany mass customization
processes even if customization is partially completed by suppliers. This approach
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does not take into account the necessary structures and processes in the mass
customizer company. Turowski simplifies the process from configuration to the
order at suppliers to one action of an agent. This can only be true if parts of the
mass customized products are completely produced by suppliers and only
assembled by the mass customizer. To implement interorganizational cooperation
for the execution of mass customization-processes based on agent systems, the
use of component-oriented implementation based on Internet-Technologies is
necessary (Turowski 2002).
Control focus Another automation based approach originates from the PABADIS project
(Pabadis 2000) which concentrates on the shop floor and is also assumed to be
advantageous for mass customization (Penya/Bratoukhine/Sauter 2003). Agents
are used for the integration of ERP-systems and automation systems in the field
area. The concept differs from other agent usage scenarios in production
environments because of its emphasis on the explicit consideration of the product
in the agent system. They suggest agent systems that model not only functions,
machines and resources, but also the product itself. The problem for mass
customization is the concentration on the field area. Although the authors
(Penya/Sauter 2003) propagate their system as suitable for mass customization, it
is not designed for mass customization. It is just a concept that may be used by
mass customizing companies in the plant to better organize the complex
production processes. Several concepts have been developed to assist the
production planning and control functions in a managerial sense, which means
that there is a focus on the efficient routing of lots respectively single units in
workshop manufacturing. Corsten and Gössinger (2000) propagate an
opportunistic scheduling (Fox/Kempf 1985) with the help of blackboard systems,
which are centralized structures that contain the agenda of MAS. The project
IntaPS (Timm et al. 2001) also uses intelligent agents for small and medium sized
enterprises to enhance their cooperation capabilities, but they also demonstrate
the application of MAS in production planning and control. Because it is an
approach for small and medium sized enterprises, they concentrate on information
logistics from the production to the partners and how to find the ideal partner for
certain tasks.
Internet Technologies in Manufacturing - 37 -
Full framework Two other approaches model the entire production system as MAS. Tseng (1997)
presented a market-oriented approach, where the entire production system is
controlled through bidding procedures executed by intelligent agents (aggregated
to job and resource agents). These agents cooperate similarly to real markets,
where prices are created by auctioning mechanisms. The model uses the common
approach of the contract-net protocol (see e.g. Sandholm 2000), where agents bid
on jobs and resources to fulfill their tasks. Tseng suggests integrating certain
attributes of mass customization manufacturing into the price mechanism. A
similar, but more precise approach was developed within the AARIA project.
Based on a decentralized manufacturing structure, agents are distributed
throughout the production system. There is a distinction between persistent and
transistent agents. Transistent agents are created by persistent agents (Baker/Van
Dyke/Kutluhan 1999), e.g. to represent a necessary job or process. The system is
controlled through a KANBAN-similar pull system, where the first step is the
customer order, which triggers further steps (materials handling etc.) to schedule
the necessary sub-processes. Brokers are negotiating between the steps within
the production systems by a so-called least-cost scheduling.
4 Managerial Approaches for Internet-based Operation Systems
4.1 Human Machine Interaction as critical Issue for ubiquitous Internet-based Infrastructures
4.1.1 Advances in Human Machine Interaction
The quality of HMI in automation is an important issue in manufacturing. This
special form of interaction occurs when the combination of human abilities and
machine features are necessary in order to perform the tasks in manufacturing.
Balint (1995, p. 135) has identified three categories of such Human-Machine
Systems:
• Machines might do the job without human involvement, but the feasibility is
questionable. For example, weld seams in car assembly are mostly
autonomously made by robots, but in many cases humans have to guide
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the robot to the weld point, because the robot is not able to locate the point
correctly, which is a relatively easy task for a human.
• Humans might do the job without machines, but the efficiency/reliability is
questionable. This is the case in almost all cases of automation, e.g. the
varnishing of cars.
• HMI is necessary (no purely machine or human-based execution is
possible) although robots today are widely in use, in many cases they
cannot substitute humans completely because the possible conflicts that
can occur are so diverse that a robot alone cannot manage them.
The term HMI is widely used for the interaction of a human and a somewhat
artificial, automated facility, which is true in many situations, including Human-
Computer Interaction (HCI). In this article we speak of HMI in industrial settings.
We use the term machine especially for industrial facilities for producing a certain
(physical) output; in this case, the term Man-Machine interaction is also used
synonymously for HMI. We define:
HMI is the relation between a human operator and one or more machines
via an interface for embracing the functions of machine handling,
programming, simulation, maintenance, diagnosis, and initialization.
The interface between humans and machines generally influences the quality of
HMI, especially in the third category of the above presented human-machine
systems. The design of the interface between humans and the machines has
dramatically evolved in recent decades (see, for example, Nagamachi 1992). The
first step have been mechanically controlled machines. With the rise of numerical
control, the interaction between human and machines changed. In that second
step, the operator no longer has an exact knowledge about how the machine is
programmed and cannot influence the processes in the machine. The third step is
computerized machines, where the operator can influence and program a wide
array of parameters in the machine. At this step, computerized HMI became a
central aspect in manufacturing on the shop floor.
The advances of computerized techniques for enriching the interface, allow a human-centred modification of HMI. This enables an effective use of the skills and abilities of the operators of machines and the features of the machines
Internet Technologies in Manufacturing - 39 -
themselves. Such a human-centred design of manufacturing technologies should obey the following steps (Stahre 1995, p. 143):
• Consider existing skills of the user
• Facilitate the maximizing of operator choice and control
• Integrate the planning, execution and monitoring components
• Designed to maximize the operator's knowledge
• Encourage social communications and interaction
The usage of interoperable, adaptive, and standardized information technologies
on the shop floor is essential to solve the problems in human-centred
manufacturing in which the above-mentioned fulfil the criteria. Due to restrictions in
the capability of computers and their associated technologies in the 80s and 90s,
the computer interfaces have been built upon those technological limits. They
were not oriented on an optimized effectiveness of the human machine interaction
on the shop floor. In addition, HMI has been machine-specific up to now and
bounded on the implementation by the facility vendor. The diffusion of Internet-
Technologies within automation and new trends in automation technologies
provide the necessary infrastructure (Blecker 2003, p. 3). The following trends are
essential:
• Mobilization of computers. For example, web pads enable the mobilization
of all interactions between humans on the shop floor.
• Embedded computing. Every machine may have an integrated full-featured
computer. It stores data, provides a front-end, can autonomously sense and
respond to the environment (by blinking, e-mail messages, software calls
etc.) and offers services for machine maintenance and control. Embedded
computers in machines and facilities on the shop floor induce the
development of “intelligent” systems in every machine. Here, intelligence
means that the system can set a wide array of autonomous (clearly
predefined) actions on the occurrence of certain events.
Internet Technologies in Manufacturing - 40 -
• Standardization of networks. (Industrial) Ethernet replaces common field
busses and proprietary networking. It is also compatible with wireless
networks, which enables wireless communication on the shop floor.
Consequently, Internet-Technologies have become ubiquitously available on the
shop floor. The data and computation services will be portably accessible from
many if not most locations on the shop floor. Internet-Technologies also trigger a
standardization of the screen design and content distribution. This leads a major
change in the traditional HMI, especially for blue-collar workers. In fact, the
interaction between workers and machines approximates the common screen
handling of the office world. Therefore, we state that the human machine
interaction is converging into a web-based Human Machine Interaction.
Web-based HMI is an advanced and extended form of computerized HMI. It is characterized by the logical separation of the computer unit from the machine itself. Internet-Technologies integrate the human as well as the machine within a corporate network. They make the entirely web-based information infrastructure, all of the interaction partners connected to it, available for the employees as well as the information systems on the shop floor. By using web-based interfaces for user input, screens can be implemented or modified rapidly. Cost savings are realized since any device (mobile or fixed) that can support a browser becomes a personal computer. The enhancements due to the use of web-based HMI in manufacturing can be summarized to the following groups:
• An ergonomic visualization in many variants (coloured, high resolution
screens and standardized visualization technologies) enables an appealing
and effective representation of data from the shop floor, and data for
example from the ERP-System.
• Hardware and software advancements enable more efficient input- and
data manipulation processes.
• The contents and screen designs are easily updateable und changeable.
• The visualization is not bounded to the computer in the machine, but
connects via the Internet – this enables the delocalization of the interaction
in various scenarios.
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Web based HMI changes and enhances several workflows especially in
manufacturing information processing (AWK 1999, p. 360). This triggers several
consequences.
4.1.2 Consequences of web-based HMI
Through the standardized technologies used in web-based HMI, all other forms of
applications that build upon Internet-Technologies are distributable on the shop
floor to every worker. The consequences affect the following fields of activity with
extended HMI processes:
• Collaboration on the shop floor
• Data collection
• Communication and coordination with the management
• HMI processes themselves
The availability of a full networked computer enables collaboration applications
e.g. workflow management systems, instant messaging and voice-over Internet
Protocol (voice-over IP) on the shop floor. Internet-Technologies enable the
intuitive integration of those technologies and interfaces that support the worker in
his or her special environment. For example, workers in the assembly may directly
interact with engineers via the IP-based speech and video connections to solve
special problems or learn cooperatively specific work processes. The aerospace
industry uses such methods for the assembly of complicated parts of planes.
Those intra-organizational virtual relationships help in reducing costs through web-
switched communication by reducing or (in the case of wireless techniques)
replacing the necessary cable lanes and a markedly eased set up of infrastructure
through the usage of open standards.
The web-based interfaces enable an accompanying data collection through the integration of data-entry screens into the normal workflow screens of the interface. The mobilization of computers allows the worker to have a personalized pad, which enables mobile data collection in various applications, e.g. logistics or quality assurance. Those pads or devices have sufficient computation power and offer connectivity to use specialized equipment, such as Bluetooth-headsets for
Internet Technologies in Manufacturing - 42 -
speech entry. The networked local computer may use a web service on a remote server for speech recognition.
The high resolution of screens and the integration into an intranet on the shop floor, push the set up of web-based training on the job in manufacturing. Especially relearned, low-educated workers show good results if they are trained in short lessons during their work hours (Schmidt/Stark 1996, p. 123). Furthermore, an effect of the extended use of computers, respectively the training on abilities to handle computers results has positive effects on the diffusion of new information systems and the resulting processes (Rozell/Gardner 1999, p. 9).
The extended web-based interaction abilities also virtualise the communication and coordination with the management of the organization. Operators have access to upper level information via web browsers and the top-down communication becomes more intuitive, which directly simplifies the coordination structures (Eberts 1997, p. 826). Although the improved interfaces have widespread effects on information handling
on the shop floor, the most important aspect remains the HMI itself. HMI has
several similarities to human computer interaction in the office world, although
there are important differences. These include the extensive application of touch-
screen interaction, and the feedback via the activities of the controlled machine.
The other interaction scenarios are comparable with common HCI scenarios.
Indeed, there are differences in the work environment (industrial settings), the
design of the computers (use of touch screens, no keyboards or mice) and the
abilities of the workers (Fakun/Greenough 2002). These differences require an
analysis of web-based HMI on the shop floor that differentiates from the results of
common HCI. The web-enabled facilities induce two contrary consequences:
• First, web-based information distribution leads to a more intuitive and
efficient HMI, which decreases the interaction complexity for the human.
This induces reduced qualification requirements because the handling of
machines requires less specialized knowledge. This leads to the hypothesis
that there are lesser skills necessary for workers interacting with machines.
• Second, the diffusion of Internet-Technologies enables a networking of
machines and information systems, which demands the usage of those
optimization possibilities for competitive improvements. This results in an
increasing HMI complexity because much more information is to be handled
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on the shop floor, which requires additional skills of the workers.
Furthermore, the span of control of a single worker over different machines
may increase. This leads to the hypothesis that additional skills of workers
are necessary.
Workers on the shop floor may not have the necessary skills for the extended
screen-oriented information handling, although they are often specialists and well
trained (Mikkelsen et al. 2002, p. 231. Therefore, cooperation between the human
resources and planning departments in manufacturing has to clarify whether the
workers should receive extended training, or whether the screen and information
design has to be adapted according to the user's abilities. To evaluate the
consequences in practical cases, we have to consider the resulting behaviour that
is necessary for fulfilling the tasks within manufacturing. Those behaviours can be
categorized as follows: (Strahe 1995, p. 145).
• Skill-based behaviour: well-learned, sensory-motor behaviour, analogous to
nearly instinctive hand and foot actions while driving a car.
• Rule-based behaviour: actions triggered by a certain pattern of stimuli. A
computer, using an “if-then” algorithm to initiate an appropriate response,
could execute these actions.
• Knowledge-based behaviour: responding to new situations. High-level
situation assessment and evaluation, consideration of alternative actions in
the light of various goals (making decisions and multifactor scheduling of
actions).
HMI has dramatically shifted the possible behaviours in operating machines. Skill-
based behaviour has dominated the pre-computerized HMI, where machines were
only usable based on the skills of workers. The rise of numeric control pushed the
rule-based behaviour into the forefront. Workers have only “assisted” the
machines by inserting punch cards, which have been prepared by engineers. The
diffusion of computerized, programmable control architectures enabled the direct
influence of skilled workers again (Strahe 1995, p. 146) and is promoted through
the upcoming web-based HMI knowledge-based behaviour on the shop floor.
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Compromising the technological advances in HMI has changed the machine control itself as well as the interaction with all actors on and outside the shop floor. To benefit from those changes, a coordinated implementation of the technology and organizational processes is required (Wu 2002).
4.1.3 Implementation of web-based HMI-Scenarios
The realization of the potential of web-based HMI requires an adequate
implementation of technical and organizational structures. First, management has
to assure whether a ubiquitous web-based HMI infrastructure is desirable. The
additional benefits of web-based HMI are only reasonable if there is demand for it
(Stolovitch 1999). Therefore, an implementation of the described technologies and
organizational changes should be accomplished if
• Extended knowledge-based behaviours are required and
• Complex manufacturing tasks with extended information processing
requirements on the shop floor are necessary.
If those tasks are not necessary, an isolated application of web-based HMI will
bring forth some benefits on the existing work processes. However, the gain of the
full potentials of web-based HMI requires an integration of the various information
systems on the shop floor, the implementation of adequate organizational
structures, managerial processes, as well as education strategies for online
training on the job. Those action fields induce bundled measures in many aspects
of the factory. We concentrate here on the issues concerning the interactions of
humans and (web-enabled) machines.
Adaptation information systems and machining infrastructure
Technological barriers are critical. Web-based HMI scenarios require adequate machinery that has embedded computation power. Moreover, there has to be a networking infrastructure. Barriers result from the existing infrastructure. Technology management has to ensure the implementation of Internet-Technologies within the production system. Facilities, as well as information systems, have to be strategically equipped with Internet-Technologies (Blecker 2004, p. 295f). This also means that existing information systems may be extended to meet the new requirements.
Development of an education strategy
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Indirect communication over different Internet-based communication technologies requires employees to have sufficient knowledge in handling information technologies. They also should have a basic understanding of how the omnipresent network operates; otherwise, they are likely to see it as a black box. This would lead to a passive use of the information network where an active use is really required. Therefore, human resource management has to train employees to meet the requirements. The training should also reduce the resistance of employees. The suggested mechanisms make the work environment more transparent. This transparency indeed has to be dealt with carefully, because it also allows the detailed reconstruction of the usage and the spying of the interaction behaviour of the employees.
Ergonomics and motivation
Yi/Hwang (2003) has shown that application-specific self-efficacy, enjoyment, and learning-goal orientation all determine the actual usage of a web-based information system. Those aspects have to be considered during the set up of a web-based human-machine infrastructure. Especially in the exposed areas on the shop floor, the design of the devices and the interaction possibilities beyond traditional HCI are important. Therefore, the distributed content has to be adopted for use on the shop floor, although the representation also has to satisfy the requirements of normal screen design as is shown in (Ozok/Salvendy 2004, p. 145f). The adoption should boil down the information to the most important messages. This can be assured using semantic technologies (Geroimenko/Chen 2003) and the use of short abstracts and keywords. The input workflows should be implemented in e.g. wizard style, so that scrolling and additional mouse-like movements on the screens can be omitted.
Production portals for visual representation
To design enterprise-wide screen guidelines based on the information system integration it is necessary to set up a strategy for visual integration of information systems as well as the machine control for the workers on the shop floor. Production portals are a solution to those challenges. A production portal is a digital enterprise portal, which is used by a manufacturing organization or plan as a means to assist their decision-making activities (Huang/Mak 2003, p.7). These portals are able to deliver adapted interfaces for example for experts or beginners with the help of dynamically generated pages based on web technologies. Through the dynamic linking capabilities of web-technologies (e.g. the use of web-services for the delivery of information from enterprise resource planning systems), the integration of all information sources into one screen design can be
Internet Technologies in Manufacturing - 46 -
realized. Due to the characteristics of work on the shop floor, multitasking is also not a desired feature. An explorer-like tree (Botsch/Kunz 2001) organizes all of the personalized features that are relevant for the worker. In this case, workers do not have to work with different application windows, but can navigate in one browser window between information sources and data entry forms through relatively simple links. summarizes the considerations for web-based Human Machine Interaction in Operations.
• Consider existing skills of the user• Facilitate the maximizing of operator choice and control• Integrate the planning, execution and monitoring components• Designed to maximize the operator’s knowledge• Encourage social communications and interaction
Trends in Internet-based Operations
•Mobilization of computers. •Embedded computing. •Standardization of networks.
Enhancements web-Based HMI• An ergonomic visualization • efficient input and data
manipulation processes.• screen designs updateable und
changeable.• the delocalization of interaction.
• extended knowledge-based behaviours are required and• complex manufacturing tasks with extended information
processing re-quirements on the shop floor are necessary.
Consequences in HMI
• Collaboration on the shop floor • Data collection• Communication and coordination
with the management• HMI processes themselves
• Adaptation information systems and machining infrastructure• Development of an education strategy• Ergonomics and motivation• Production portals for visual representation
Requirements for Effective Human Machine Interachtion (HMI)
Application Fields
Implementation
Source: Graf (2006), o.S.
Figure 11: Origins and Implementation of web-based Human Machine Interaction
4.2 Actor-oriented Perspective for managing the Information Architecture
4.2.1 Fundamentals of the Actors Approach
The actors oriented perspective concentrates on acting units in the operation
system. Actors are persistent, which means they exist over an essential period of
time in the operation system. The actors of the production system have a broad
set of abilities to build up relationships with other actors (Blecker 2005). Thus, we
can claim, that every actor may interact with every other actor. The existing
relationships build up the potential processes that may be set up in the case of a
reconfiguration. Relationships are the basis for transactions. Transactions are the
exchange of parts and materials as well as of information (Blecker/Graf 2004a).
Internet Technologies in Manufacturing - 47 -
Additionally, the interaction of actors is not limited to the production system, which
means that they can communicate or exchange with actors outside the production
system. We concentrate here on the transactions of information and factor out the
physical transactions. We assume that qualities and capabilities of each actor
change by applying Internet-Technologies for their interconnection on the shop
floor. Additionally, a decisive influence of modifications of the actors' capabilities
and/or of their coactions on operations management is conjecturable. The exact
content of coordination between the different actors, their organization and
interaction in general, determine the physical and economic output of the
production system.
Actors
informationtechnologicalmechanical
human artificial organizational
monolithic composed
diffe
rent
iatio
n re
gard
ing
the
acto
rs’c
ompl
exity
diffe
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iatio
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gard
ing
the
acto
rs’e
lem
ents
Agent System Mass Customization Company
Actors adopting the behavioral role as agents
Software units that are not actors
Actors
informationtechnologicalmechanical
human artificial organizational
monolithic composedmonolithic composed
diffe
rent
iatio
n re
gard
ing
the
acto
rs’c
ompl
exity
diffe
rent
iatio
n re
gard
ing
the
acto
rs’e
lem
ents
Agent System Mass Customization Company
Actors adopting the behavioral role as agents
Software units that are not actors
Source: Blecker/Graf (2004), p. 14
Figure 12: Actors in Production Systems
We differentiate three types of actors in the operation system. The first type
consists of human actors, e.g. planners and workers. Because of the increasing
integration of modern information and communication technologies into
automation systems and their growing local „intelligence”, artificial actors build up
the second type of actors in production systems. For example, facilities with
embedded computational intelligence may act autonomously in a production
process. As in human actors, they perform different tasks and interact with other
actors in the production system under physical and cognitive limitations
(Baldwin/Clark 2003). The third type of actors consists of composed units. We call
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this type organizational actors, because they consist of a varying number of
human and/or artificial actors following organizational principles, e.g. autonomous
or virtual teams on the shop floor, and act as a whole.(Blecker 2003).
This paradigm is similar to agent-oriented views on information systems. Yu (2001, 123f.) suggests to model agents with intentionality, autonomy, sociality, contingent identity and boundaries, strategic reflectivity as well as rational self-interest. In an economical perspective, agents are discussed in an institutional approach analyzing especially the information exchange problems between agents. In multi-agent manufacturing systems, agents may represent single resources (a work cell, a machine, a tool, a worker involved in a process, etc.) as well as products or customers (Reaidy/Massotte/Diep 2003). For example, Reinhart (1997, 244f.) already proposed so-called autonomous production systems in which human and artificial agents act cooperatively and widely independent of central production planning and control.
The actors in our model may also be viewed as agents. We understand agents as a specific role of an actor in the production environment. Actors act on behalf of another actor. In this case we call them agents, still having the same attributes and abilities as before. Therefore, a multi agent system consists of a number of interdependent actors that are acting on behalf of other actors. They all have a specific role of an agent. However artificial or human actors cooperate with actors (playing the role of agents) in the MAS, but cannot be a part of MAS (Blecker/Graf 2004b).
Actors exist for a longer period of time in the operation system. Therefore, some agents are not actors in the manufacturing system. For example an agent that is created to represent a single order may last only a very short period of time. That is why we differentiate between Software Actors, that may be some Information systems e.g. for product data management and Software agents.
4.2.2 The Actors Approach in Internet-based Environments
The Actors approach stresses the autonomy of the acting entities in the operation
system. The use of Internet-Technologies as a ubiquitous infrastructure enables
the information-technological independence of each actor. In a first step, every
actor may have its IP-Address and provide certain web-based information or data
connectivity. Modern frameworks for the implementation of distributed information
architectures such as Microsoft.Net or SunONE also provide rich interfaces for
complex data manipulation and exchange processes for embedded systems and
Internet Technologies in Manufacturing - 49 -
even with shortened computing power. Thus, every actor can provide full
information technological functionality to the network. Moreover, the main user,
e.g. an employee controlling a machine via a web based front-end also does that
via that interface.
The most dynamic areas in Internet-Technologies are on the one hand Web
Services for the integration of heterogeneous Information Systems (Hammer 2004,
p. 23). On the other hand, the Semantic Web and all necessary technologies for it
are an important development for enriching the data quality in Web Applications.
An integration of these approaches occurs with semantic web services. Through
process description languages such as the Web service flow Language (Leymann
2001) a conversion of complex service nets about numerous service providers is
enabled. A dynamic behavior of decentralized operation systems, which
autonomously construct processes (from the static binding to the dynamic binding
(Kreger 2001, p. 8) requires however further complex mechanisms. These are in
particular economic ones (such as pricing- and billing model) and legal general
conditions (as the contract ability of services) that one must consider. Here the
concept of Web Services approximates the concept of virtual Software Agents
(Beimborn/Minert/Weitzel 2002, p. 277). Two initiatives exist for the evolution of
machine-to-machine environments in order to adapt web services for the
interaction with end users. Standardized interfaces for the communication with
human actors are provided among other things with the WSUI specification (Web
service user interface). This specification describes complex end-user applications
that can be embedded in web pages or in production portals
(Bullinger/Gerlach/Rally 2000, p. 359f) in manufacturing. These technologies
provide a comprehensive framework for a description of the abilities of actors.
The most important issue when converting the information technology of actors to
web services is to dispose the vendors of facilities and information systems to
implement the interfaces with WSDL (Web Service Description Language) and to
allow SOAP-based (Simple Object Access Protocol) procedure calls. Due to the
capabilities of an embedded system, the hardware supports this claim. Therefore,
only the necessary abilities to implement and maintain the interfaces as a web
service have to be obtained by the vendors. Web services require higher
Internet Technologies in Manufacturing - 50 -
development efforts than traditional approaches for web applications (Stiemerling
2002, p. 444).
The use of web services enables the convergence of the machine to machine
communication and the human machine interaction, which is necessary for a fast
implementation of new processes for transforming the production processes.
Krallmann mentioned that the problem of the integration of humans into the
processes in Holonic Manufacturing systems is widely unsolved
(Krallmann/Albayrak 2001, p. 295). Through an implementation of a Universal
Description, Discovery and Integration (UDDI) based directory, which represents
the characteristics of all actors available in the operation system, the coupling of
the Internet-based, web services enabled actors can be realized. As a final step it
is necessary to standardize the used terms and concepts throughout the
information systems in the operations.
4.2.3 The Actors Approach as a top-level Ontology
The actors approach structures the heterogeneous operating units in different
organizations. To enable an implementation of our considerations, the web-service
based interfaces of the actors has to follow a concept that allows the above
described explication of abilities and capacities of actors. This allows composing
ad-hoc manufacturing processes as well as a flexible scheduling of tasks.
Although we assume here that all actors have a web-service as an interface, a
directory based on UDDI for locating the web service respectively the actors is
necessary to structure and norm the capacities and abilities of the actors. This
norm can be realized by the development of an ontology based on the actors
approach. An ontology is an explicit specification of a conceptualization (Gruber
2003, p. 199). The ontology has to provide the essential abilities of actors in the
production network. Based on an explication of the abstract abilities in the actors
approach, a unification of the available services in the production network is
realizable. An actor's based ontology provides the necessary explicit knowledge
constructs, to classify the actors in the production network. Based on this
classification, an implementation of a directory containing all actors with their
abilities is possible. Alaparslan et al. (2002, p. 45) present an approach for an
Internet Technologies in Manufacturing - 51 -
information system, which actively contributes to a better utilization of corporate
knowledge about employees' competencies.
To dynamically use web services, a framework that enables communication
without code generation is necessary. For java-applications a Web Services
Invocation Framework (WSIF, http://ws.apache.org/ wsif/) exists. Corresponding to
the elements of a WSDL-Description, the WSIF defines classes, which can be
parameterized by a WSDL. Based on this approach, it is possible to
spontaneously use every thinkable Web Service (Dostal/Jeckle 2004, p. 61).
In operation systems, an actors' ontology based UDDI-directory can provide the
automatic location of web-serviced based actors with their abilities and capacities.
The directory contains the information based on the WSDL-documents provided
by the actors. The actors' ontology provides a notion for the mapping of certain
characteristics of the actors' abilities and the possible tasks in the actors'
approach. This infrastructure enables the identification and composition of actors
to implement new value creation processes.
To enable a decentralized scheduling to a large extent, the ontology also has to
integrate the capacity of the actors. Based on this, a central planner can estimate
the due dates of an order. The autonomous detailed scheduling by the actors is
possible because the local information system provides in real-time the progress
of a certain production step. The mentioned tracking agents can permanently
readout the information from the Web Service of an actor. The overall coordination
can then be implemented e.g. by blackboard systems. Through the ability oriented
modeling of resources, the matching of heterogeneous planning approaches in the
participating companies can be reached without having to implement an overall
planning system, such as APO for SAP-Systems.
Internet Technologies in Manufacturing - 52 -
5 Implementation considerations of Internet-based Multi-Agent systems in operations
5.1 Application of Multi Agent Systems in Internet-based Operation Systems
5.1.1 Rationales for Internet-based Multi Agent Systems
There has been a lot of research in the area of multi Agent Systems in
manufacturing so far. Nevertheless, there are only few examples of successful
implementation in operation systems so far. We assume that one reason for this
situation is the lack of high level application Frameworks on a high level for
production management. Therefore, it is necessary to merge the technological
insights presented so far to an application framework, which shows clearly the
interdependencies of the different Technologies and their influence on the
applicability of multi agent systems. We do this by formulating propositions that are
based on the findings presented so far. We add some conceptual considerations
to form an congruent Framework for the application of MAS. For the concepts
presented in chapter 1.1 we can formulate 2 Propositions:
(P1) Internet-Technologies become a ubiquitous platform respectively an omni-
present information infrastructure in the complete industrial firm.
(P2) The convergence of information and production technologies enables the
revision of traditional Production Concepts or even the development of new
Production Concepts.
The considerable advantages of Internet-Technologies are uncontroversial for the
technological infrastructure of communications and information in production
processes. There are several approaches in literature, which use Internet-
Technologies purposeful for the design of Internet-based Production Concepts.
Those aim to realize more competitive operations based on the application of
Internet-Technologies in Manufacturing.
The Information-Based Manufacturing describes a highly information-dependent
production, which is distributed through several enterprises. It shows a strong
customer relationship (Shaw 2001). Exemplary instruments of Information-Based
Manufacturing are optimal information sharing about the supply chain, a high
Internet Technologies in Manufacturing - 53 -
velocity of (re)actions, and an optimal synchronization of production factor
appropriation and scheduling between the firm and their partners in the entire
supply chain. Therefore, companies have to have agent systems, decentralized
planning and operation systems as well as integrated information and automation
technologies in the dislocated production processes for the realization of
Information-Based Manufacturing. Thus, the commitment of Internet-Technologies
does not occur intraorganizational, but mainly interorganizational, e.g. based on
WebEDI, or during the communication with the customers. The focus of this
approach differs obviously from our intraorganizational perspective.
Another concept is the e-Factory, which considers the necessary qualities of
industrial firms. The author understands the e-Factory as an upright element of an
electronic supply chain in E-Business and defines this approach as „a new, all-
encompassing term for all of the electronic control, automation, and intelligent
machines that occupy today's factory environment” (Beavers 2001). Main goals
are a quickly reacting production system, a high process orientation as well as an
integration of the own enterprise into the supply chain. Intraorganizational
instruments are electronic control systems for all automation technologies and an
extensive application of information systems, e.g. ERP, Warehouse Management
System and PDM/EDM. We share the fundamental perception that modern
information and communication technologies penetrate the production processes
and pass the production up to the automation level as well as to the machine
control.
Positive approaches for the application of Internet-Technologies in manufacturing
are observable in context with the keyword 'Web-Integrated Manufacturing' in
engineering research. Web-Integrated Manufacturing describes the general
application of Internet-Technologies in manufacturing, for example, agent based
systems, Java, Jini and SOAP (Kühnle/Klostermeyer/Lorentze 2001). Even the
international research project „plant automation based on distributed systems”
(http://www.pabadis.org/) uses this approach as theoretical basis and aims at the
development of decentralized, distributed systems of the office communication
within the machine control on the shop floor. This is supposed to lead to highly
flexible, adaptive and simply reconfigurable production systems [8].
Reconfigurable production systems combine the respective advantages of high-
Internet Technologies in Manufacturing - 54 -
productive and high-flexible systems, because they can be adapted immediately
regarding their structure, functionality, capacity as well as their inherent technology
to changing demands. For the realization of this scenario companies need a
distributed problem solving (DPS) and MAS in automation on the shop floor.
Therefore, Web-Integrated Manufacturing focuses on decentralized agent system
in manufacturing and embedded systems in automation technologies.
Furthermore, these agent systems have to substitute occasionally existing
Manufacturing Execution Systems (MES).
Recapitulating the excerpted Production Concepts applying Internet-Technologies
and their specific motivation and considering the presented advancements for
Internet-based information system architectures, we can state:
(P3) Internet-based Production Concepts enable decentralized structures and
lead to seamless and continuous information flow between the specific actors in
the production process.
(P4) Modern, success promising Production Concepts concentrate on the
improvement of production processes by applying Internet-based FAN.
Fundamentally, the industrial firms may apply Internet-Technologies and MAS
within as well as between all organizational and/or technological levels. If we
follow a top down approach, we have to state that the major application field is the
automation of the management level respectively PPC. Additionally an actual
trend is the integration of this level with the more technical levels such as process
execution. Therefore, decentralized assembly lines are interconnected with
Internet-based FAN and a detailed data sharing between the FAN and cooperative
Ethernet Networks is enabled. This leads to direct communication between ERP,
PPC, MES and Automation Technologies in the sense of Enterprise Application
Integration (EAI). Yet, due to heterogeneous standards of information systems the
planning and execution levels are frequently unconnected or incompatible. MES
interconnect these two levels up to now and transform the data from shop floor for
the ERP et vice versa. This integration is an open, interoperable solution instead
of using MES. Active Technologies such as MAS, Web Services and Industrial
Frameworks for Internet-based FAN enable the development of web based MES
or even their substitution (Blecker/Graf 2003, p. 28). Thus, we assume:
Internet Technologies in Manufacturing - 55 -
(P5) Internet-based FAN and MAS on the shop floor as well as Internet-
Technologies in office automation enable Web-based Manufacturing Execution
Systems, sometimes even their substitution through Web Services.
(P6) The more the availability of real-time data from shop floor increases, the
merrier new PPC mechanism as well as continuous information and
communication structures between administrative and production systems are
realizable.
Besides the vertical integration of information systems a second trend in industry
exists: From a horizontal point of view many production and information concepts
try to realize decentralized structures and to merge production and information
systems on the shop floor, e.g. in favor of holonic manufacturing. These concepts
aim at the dissolution of hierarchies and modern organization forms in
manufacturing. The main goal is to lower the complexity of the production and
information systems in order to improve flexibility and reaction time by
implementing process oriented workflows. Yet these concepts have immense
prerequisites regarding networking on the shop floor. From the concepts of
decentralization and modularization results a structure on the shop floor which
requires distributed application architecture with distributed databases to integrate
the decentralized information of the units. We consider Internet-based FAN
appropriate to support this architecture, because of the higher flexibility, higher
connectivity and scalability than conventional FAN like ProfiBus or LonWorks. The
most important aspect of Internet-based FAN is the changeover from a master-
slave infrastructure to client-server architecture. Thus we can say:
(P7) Internet-based FAN are crucial for the interconnection of decentralized
machinery in plant automation, as aimed in modern Production Concepts.
We assume that it is necessary to swap from computer integrated to Internet-
based Production Concepts. A difference between these two philosophies is that
CIM focuses on an integration of different, dislocated subsystems of the planning
and operation of production processes. If we consider this integration as
constitutive for Internet-Technology based Production Concepts too, it is only a
necessary, but not a sufficient definition criterion. In particular, we regard the
centralistic integration intended in former Production Concepts as technologically
Internet Technologies in Manufacturing - 56 -
and organizationally obsolete. Internet-based Production Concepts emphasize that
the application of Internet-Technologies on the shop floor represents an important
basis of an economically successful production in future. Therefore, these
concepts consider the application of Internet-Technologies as focal component,
not only integrating element. The overall application of Internet-Technologies in
the production processes and/or their combination with the automation
technologies reduces the central coordination and control as well as the formerly
forced heteronomy of the actors in production processes. Thus, our next
proposition:
(P8) MAS in Internet-based FAN enable decentralized coordination and
operation mechanisms as well as at least partial self-determination of the actors.
This means, that industrial firms can apply the already known concepts of the
decentralized PPC as well as partially autonomous manufacturing technologies
more effective. A further advantage of Internet-Technology based Production
Concepts is that they reduce the up to now rigid, but often inflexible infrastructures
and the resulting high configuration intensity. Internet-based infrastructures will
enable flexible, easily reconfigurable production systems. In contrast to early
highly automated systems, the new production-near Internet-Technologies on the
automation level allow a distributed automation with a high flexibility. In the case of
a consistent usage of sophisticated Internet-Technologies, our next proposition
assumes that
(P9) Industrial firms gain the advantage to approve unsolicited modifications in
the production processes respective the underlying structures on the shop floor, so
that they will achieve an infrastructure in the sense of „plug and produce”.
In sum, industrial firms obtain a vertical integration as well as a horizontal
decentralization from the implementation of MAS and Internet-based FAN in
production processes. Particularly new is that on the one hand, office information
systems can be interconnected to production systems and on the other hand, that
plant equipment can be integrated up to individual actors and sensors into this
concept. A cooperation of different, up to now often independently of each other
acting sections in the enterprise occurs. Frost & Sullivan name this a reunification
of planning and control in all production processes (Frost 2000). This is a new
Internet Technologies in Manufacturing - 57 -
development, which constitutes a redesign of production systems. The redesign
leads to the application of decentralized, distributed systems of the office
communication within the machine control on the shop floor. This is supposed to
result in highly flexible, adaptive and simply reconfigurable production systems.
Reconfigurable production systems combine the respective advantages of high-
productive and high-flexible systems, because they may be adapted immediately
regarding their structure, functionality, capacity as well as their inherent technology
to changing demands. Due to the intelligence implemented into local machines
and the control by autonomous intelligent agents, the described factory
infrastructure leads to the ability for partial problem solution in specific equipment
and/or a workgroup on the shop floor. In combination with the attributes of problem
decomposition, delegation of sub-problems and constructing partial solutions to
the overall solution resulting from decentralized and modularized structures on the
shop floor obtain an essential basis for distributed problem solving (DPS) in
production. DPS has the ability to consider much more parameters than
conventional approaches e.g. in PPC and load balancing (Kirn 2002). On the other
hand, DPS is not suitable for bottom-up Problems and for coordinating
denaturalized units. Thus, international projects focus on decentralized MAS in
manufacturing and embedded systems in automation technologies (e.g.
PABADIS). On the other hand, useful problem decomposition is required.
(P10) MAS for planning and control of all industrial processes in Internet-based
production systems enable DPS in automation technologies on the shop floor.
The application of MAS and DPS in a modern production system creates a new
distributed artificial intelligence architecture that can handle complex information
processes. Industrial firms may gain major competitive advantages from such a
change in the production system. At least since the middle of the 90ies it is
indisputable that the main reason for parallel or distributed architectures in
manufacturing and MAS as well as DPS in production is flexibility (Kirn 2002).
Further Benefits result from structuring inelastic, extensive super-systems into
small, high performing actors. Potential frictions, which may arise if central
coordination systems are necessary in order to assure a problem adequate super
system, are avoided because of a decentralized coordination. Therefore it is
justible to assume that the high flexibility of the production system, the vertical
Internet Technologies in Manufacturing - 58 -
integration of all related information systems and the horizontal decentralization
resulting from the overall implementation of an Internet-based infrastructure and
MAS lead to a high reconfigurability of the whole factory.
(P11) Internet-based Production Concepts establish reconfigurable production
systems based on the implementation and optimal application of Internet-based
FAN and additional active, intelligent technologies. Thus, they significantly
contribute to highly flexible and agile production processes as well as major
competitive advantages for the industrial firm.
From a Multi Agent System perspective, existing information systems may be
integrated into the new Internet-based, agent-oriented environment by enhancing
them with Internet-Technologies and logically encapsulating them into an Agent.
Thus, this problem seems to be manageable. A more serious problem is the
absence of suitable; Internet-based Production Concepts, which realize benefits
from MAS and Internet in POM. This results in a situation where a company
applies MAS and Internet-based FAN in an optimal way, but is not able to
generate benefits for the whole production system such as the intended
information transparency, high flexibility and/or competitive advantages on the
market.
5.1.2 Implementation Framework
A successful implementation of MAS in Internet-based environment depends on
the application of the suitability of information technology, information systems, as
well as the organization. There are several barriers that need to be overcome by
applying the suggested organizational structure, the necessary information
systems, as well as the prerequisites for the application of MAS.
First of all, the discussed decentralization is to be realized effectively. Additionally,
the actors approach requires a modularization of the organization. Management
has to hand over competencies to other actors. There are several problems to
consider. First of all, the actors must be able to cope with the additional
(management-) tasks they have to fulfill. Therefore, human actors have to be
trained well, to handle the responsibility and the coordination tasks that have to be
done autonomously. What is important is the embedding of artificial actors into the
organization. The consideration of organizational actors is an additional issue. The
Internet Technologies in Manufacturing - 59 -
problem of different modularization concepts is a lack of explicit interfaces
between the different organizational units. Organizational actors allow the
considering of e.g. a work cell as a unit. Based on this, it is possible to define
clearly the in and outputs of such an organizational actor. This is necessary to
allow an efficient interaction with artificial actors.
From a human resources perspective, management, as well as employees must
be prepared for working in this suggested environment. They have to be able to
understand what artificial actors are and what they are able to do. Artificial agents
in an Internet-based production environment differ from previous approaches,
because they are acting closer with human agents. This means, MAS are no
longer an nontransparent black box in a remote information system. They are now
a part of the organization, because they are participating directly in different
processes. Thus, it is necessary to explicitly define the actors and their attributes.
The definition of actors also supports decentralization, because the decision rights
of the actors are defined.
Technological barriers are also critical. Internet-based production concepts require
adequate machinery that has embedded computation power. In addition, there has
to be the necessary networking infrastructure. Additionally, barriers result from the
existing infrastructure. In many cases, industrial firms have to protect their existing
investments, so they have to continue in using a technologically obsolete
infrastructure. Furthermore, in some cases, the application of specialized, non IP-
based machinery is necessary and/or the cost of a complete migration to Internet-
based field area networks a prohibitive high. Companies can solve this problem
with gateways between the field busses and the Internet-Technologies or the
application of convergent infrastructures. Big suppliers in the field of the
automation technology offer already corresponding solutions or even Internet-
suitable fieldbus-systems such as ProfiNet.
Two fundamental problems in information technology are optimal implementation
and security. While the original implementation problems of Internet-Technologies
and their implementation in production processes are well known, security aspects
are the main obstacles and barriers to industrial applicability. Although security
aspects are not considered in many cases by the implementation of Internet-based
field area networks, there is a main risk that important machines and plants are
Internet Technologies in Manufacturing - 60 -
exposed to different attacks, e.g. by hackers, viruses and trojans. These problems
arise especially when customers and suppliers connect their systems to the new
infrastructure on the shop floor directly, e.g. in mass customization. However,
technical and/or organizational protection mechanisms already known reduce the
problems, e.g. cryptography, virus scanner, firewalls, and access controls.
An Internet-based infrastructure and the adequate organization structure given;
MAS may be integrated in the production environment. There are many concepts
that have developed mechanisms for the coordination and the problem
decomposition in MAS. These approaches do not plan out the implementation, but
concentrate on the conceptual draft of the necessary mechanisms and the
separation of different agents. Other approaches try to implement these
mechanisms experimentally. Except the Pabadis approach, there are no projects
that are trying to use MAS in actual environments. Therefore, there is a barrier for
application because ambitious companies would have to engage in research
projects to implement MAS. The presented approach allows the introduction of the
MAS approach systematically. This means that especially dispositive actors in the
production environment may be replaced through information technology or that
machines will be extended with actors’ capabilities a now may be represented by
an agent.
For the application of multi-agent systems, there are mechanisms needed to
locate actors and their attributes in the production system. The directory of
resources is a promising concept to link the information stored in the various
information systems to the organization and therefore make it applicable. In fact,
this concept is a management tool to cope with complex organizations broadly
supported by information systems. A rudimentary version is the DNS (Domain
Name system) of the Internet, which matches domain names to the IP-addresses
worldwide. A more complex standard for that is UDDI (Universal Directory
Description Interface), which we presented in this paper. Apart from the technical
concepts, the idea of the directory approaches is to link the information within a
system (e.g. production system) to the various resources within the system. The
directory stores the attributes of every actor within a system and represents its
attributes. The directory enables the actors of the concerned system to find and
interact with all of the other actors. The Internet-Technology based approach
Internet Technologies in Manufacturing - 61 -
allows a universal directory for the entire system, which was prohibited thus far by
the technological barriers. The directory also contains the information necessary to
set up information transfers and determines which information an actor can
provide.
However, with the presented propositions, we showed the advantages of a unified
view on the production system considering information technology, automation
technology and Production Concepts. This unification leads us to the conclusion,
that a successful implementation of MAS on the shop floor requires not only the
implementation, but also the consideration of automation technology, information
technology and the application in POM in the form of a Production Concept (PC).
Thus, we can aggregate the formulated propositions to a conceptual framework
(Fig. 1).
Infrastructure Specific Applications
inte
nded
Ben
efit
appl
ied
Tech
nolo
gies Internet
Techno-logies as
ubiquitousFAN (P1)
Conver-gence of
Automationand
InformationTechnology
(P2)
revision of traditional or de-velopment of new PCseamless/continousinformation systemsbetween the specific actorsin production
Internet based PC’s enabledecentralized structures (P3)Many modern PC’s improveproduction processes byapplying internet based FAN(P4)
Production Planning & Control
Process Execution controlled byinternet based FAN
vertical integration / EAIdiffusion of Real TimeDatareduction of complexity
Interconnection of de-centralized machinery (Plug -and Produce) (P7, P9)decentralized coordinationand operation supported byMAS (P8)Self-Organization (P8)
reconfigurable factoriesbased on Internet-FAN(P9)Web based Manufacturingas new approach toindustrial production (P11)
Production System
originalimplementation
problems
protection ofinvestments
integration ofexisting
infrastucture
utilization of MASand Internet
benefits in POM
distributedproblemsolving inmanufac-
turing (P10)
MAS inte-gration & webenhancement
of existingsystems(P5, P10)
information transparancyhigh flexible, agileproduction processescompetitive advantages
enablesMAS in
Manufacturing and POM
constitutes a(re)design ofproductionsystems
Und
erly
ing
Pro
du-
ctio
n C
once
pt(s
)
Internet Tech-nologies and/or MAS
(Real Time Data)
(P5)(P6)
Source: Authors
Figure 13 Application Framework for MAS in Internet-based Production Concepts
It aims at describing the necessary infrastructure, specific applications in industrial
processes as well as the resulting production system, at each case across the
category groups “applied technologies”, “underlying Production Concept(s)” and
“intended benefits”. Additionally we implemented the main obstacles and barriers
for an industrial application of MAS in an Internet-based environment.
Internet Technologies in Manufacturing - 62 -
Compromising, this model is neither a description of fundamental steps for the
implementation of MAS nor an axiomatic concept of the (re)design of production
systems. It is a guideline for the discussion of the interdependencies of MAS and
Internet-based Information Systems in industrial processes and Production
Concepts. It shows potential economical and technological advances for industrial
firms.
5.2 Application of Multi-Agent-Systems in Internet-based Environments
5.2.1 Reconfiguration of the Production System
Variable actors in the operation subsystem are an essential condition of flexibility.
Nevertheless, the mobility and/or the variability actors were examined in the
previous production research for flexibility only in relatively narrow confines. The
communication network enables actors to continuously form new (bi- and
multilateral) interconnections. The resulting volatile transaction networks formed
between the actors in the operation subsystem enable „fluid“ structures or even
interorganizational spherical networks (Miles/Snow 1984). For example, many
actual research projects aim at the development of high flexible infrastructures that
enable even the spatial mobility of heavy load facilities (Mobile Produktion 2003).
These approaches are the basis for a extended reconfiguration of the production
environment. The main problem of reconfigurations is to ensure the efficiency of
the new configuration. An often-discussed tool to gather the necessary information
is simulation. Simulations may run on real-time data of the existing system,
considering the desired changes of the analyzed domain (Pine 1993). In addition,
the generation of the tested scenarios is a field for MAS. Manufacturers can
generate different scenarios with the help of MAS (Wiendahl 2001,Yu 2001).
The reconfiguration in organization requires the adaptation of the information
systems, as in production planning and control system, the product data
management and also interconnections to other systems, because the change in
the production system often changes the production possibilities. The use of MAS
in one of the effected information systems will reduce the altering effort, because
single agents represent the changed facilities in the production system. In such an
infrastructure, MAS are not encapsulated into one system, but evolve by the
Internet Technologies in Manufacturing - 63 -
connection of different static agents through a number of mobile agents, where the
form of communication, trading, and the transactions are standardized. This
structure leads to a strong similarity of organizational and information system
structure. That also permits one to simultaneously attach changes in the structure
in the organization in the information system.
Structural changes cause in many industries huge efforts. Therefore, companies
try to hold a specific structure as long as efficiently possible. One possibility to
alter the system by keeping the structure constant is to reconfigure the material
flow system. For example, autonomous driverless robots are an example that
allows more flexibility and also efficiency in the production system, without
changing the structure. Robots can support the material/part flow in the variant
production, if it is not possible to implement conveyors or new circumstances such
as additional variants making those systems insufficient.
Internet based Actors Conventional Approach Black-Box use of MAS
Identification of change necessity
Design of changes
Changes in PS Changes in PPC
New Configuration
Identification of change necessity
Design of changes
Changes in PS
New Configuration
Identification of change necessity
New Configuration
Des
ign Apply
(Sel
f org
aniz
ed
adap
tion
in P
PC)
Internet based Actors Conventional Approach Black-Box use of MAS Internet based Actors Conventional Approach Black-Box use of MAS
Identification of change necessity
Design of changes
Changes in PS Changes in PPC
New Configuration
Identification of change necessity
Design of changes
Changes in PS
New Configuration
Identification of change necessity
New Configuration
Des
ign Apply
(Sel
f org
aniz
ed
adap
tion
in P
PC)
Identification of change necessity
Design of changes
Changes in PS Changes in PPC
New Configuration
Identification of change necessity
Design of changes
Changes in PS
New Configuration
Identification of change necessity
New Configuration
Identification of change necessity
Design of changes
Changes in PS Changes in PPC
New Configuration
Identification of change necessity
Design of changes
Changes in PS
New Configuration
Identification of change necessity
New Configuration
Des
ign Apply
(Sel
f org
aniz
ed
adap
tion
in P
PC)
Source: Authors
Figure 14: Alternative Reconfiguration paths in different Environments
Figure 2 shows the differences between an actors-oriented reconfiguration and
other approaches. The exclusive use of MAS only reduces the efforts of changing
the system, in which MAS are used. The conventional approach is the step-by
step approach is in high volatile environments with an need for fast changes often
insufficient. The sequential implementation phases (with eventually necessary
feedback-loops) are time consuming. In such an approach the advances in
Internet-Technologies in operations are not used effectively. This concerns mainly
the possibilities of embedded computers, but also the potentials of Web-Services
in connection with autonomous Agents for the (partial) self-adaptation of the
information infrastructure. In a second scenario, the abilities of new Internet-
Internet Technologies in Manufacturing - 64 -
Technologies are used to perfectly fit the Information System (like PPC) to the
operations structure. This means, that the Information System is designed to adopt
changes in the physical structures directly. This enables to omit an specific design
of PPC and also the necessary changes in the PPC. This is also what happens
normally in operations system, but without any direct adjustment of the PPC to the
structure. In the most cases a standardized product is used, that more or less fits
to the infrastructure.
The third scenario is an integrated consideration of the physical design of the operation system and the design of the information system. Hereby the abilities of information systems are used to effectively rebuild the operation system. Internet-Technologies allow orientating the design informational criteria. The interlinking of human and artificial actors allows an bidirectional adjustment in the case of reconfiguration. The reconfiguration has not to be planned strictly before the reconfiguration. The management instead has to ensure that all necessary resources for the realization of the configuration are available in the operation system. Through the communication of the necessary new output of the operation system, a partial self organized reconfiguration is possible. Necessary conditions are the incentive systems for the human actors, the flexibility of the artificial actors and the availability of the necessary abilities of actors in the operation system. We are concentrating here on the technological possibilities of Information Technologies; therefore we are not further explicating these conditions. They are described in literature comprehensively.
5.2.2 Production Planning and Control
It follows that modifications of the operation subsystem due to Internet-
Technologies also lead to modifications of the production planning and control. In
other words: The concrete organization of an operation subsystem is important for
the design of the production planning and control.
The conditions' precedents for optimal production planning and control are first of
all functioning information processes within the operation subsystem (Miles/Snow
1994).Therefore, efficient production planning and control requires a concept that
allows handling the high number of orders, which have a high grade of uncertainty
and have rarely the same attributes. Conventional production planning and control
concepts are not designed to cope with such a situation; they are either designed
for a large number of similar orders (mass production) or for a small number of
Internet Technologies in Manufacturing - 65 -
different orders (job shop production). Both are often based on the MRP II
approach, which is applicable for both cases, but the MRP II approach has a
centralistic focus. Zelewski (1998) summarizes the problems with central
coordination concepts for production planning and control, under a control failure,
a motivation failure and an implementation failure.
The control failure relates to the problems of centralistic production planning and
control concepts if there are uncertain conditions or unsteady demands,
summarized in the literature under „turbulence”. MRP II-based production planning
systems were often criticized for not being able to produce optimal results. This is
because of the successive planning structures that do not allow any adequate
reaction to changes in lower planning layers (Steven, 2000). Additionally, central
concepts get „nervous” when they have to deal with planning shocks, which
means that the production planning and control system is not able to adapt to
changes in the order situation or loss/change of production e.g. machine
breakdown. Especially in mass customization these scenarios occur frequently. To
cover the problems of centralistic (MRP II-based) approaches several
decentralized planning techniques were developed, but mainly for use in the job of
shop production (Corsten/Gössinger 1998). Therefore, we have a lack of
techniques for a high number of variants with higher production quantities, if MRP
II-techniques are not adequate. MAS respectively the negotiation-based
generation of a production plan by MAS are likely to be suitable for the application
in highly volatile situations. The independency of actors makes the planning more
fault tolerant, because they can react independently without having to coordinate
with a central authority.
Furthermore, central production planning and control systems cause a motivation
failure, because the actors in the production system have no freedom for semi-
autonomous planning. Especially in the complex planning and controlling in the
case of high amounts of variants, a decentralized planning would enhance overall
planning capabilities, if adequate communication and coordination structures are
provided. This is necessary, because a decentralized planning requires
coordination with other actors that have decentralized decision competences.
Therefore, the actors in the operation subsystem should be enabled for processing
of the information corresponding to production planning and control locally. The
Internet Technologies in Manufacturing - 66 -
decentralized information processing capacity of the agents postulated allow the
required information quality, as well as quantity. Autonomous, intelligent software
agents may process much of these communication efforts. Software agents are
inherently designed for executing information and coordination tasks. Therefore,
agents in Internet-based operation systems may take over coordination actions as
was presented by Corsten (1998) and Zelewski (1999). Internet-based agents may
also interact with human actors over an interface, so that these agents support the
human actors or obtain the necessary inputs from human actors that are now
participating as agents in the MAS.
The decentralization of the production planning and control concept is also to be
reflected in the implementation of the production planning and control system. It is
also today that in decentralized structures central systems are used for the
planning. Zelewski calls this issue the implementation failure. To solve this
problem, a fit of the production planning and control concept with the information
system and the used techniques are necessary. The use of Internet-based
production environments support this fit, because Internet-Technologies are
inherently modular and therefore the resulting information systems, in this case the
production planning and control system. The actors approach allows implementing
the production planning and control system as a multi-agent system, because the
production system structure supports natively the necessary separation of
domains for the design of software agents.
Internet Technologies in Manufacturing - 67 -
Order Agent
n
Human 1..n
Mech-anical1…n
Organi-zational
1…n
Coordi-nation
Handling
Coordin-ation
inventory
Coordi-nation Trans-
port
Softw
areActors
Softw
are A
gentsP
hysicalActors
Configuration Operations
Order Agent
2
Coordination of Orders
Dezentral Coordination based on the Actors Approach
Configurator, Call Center
Coordination of Resources
Order Agent
1
• Interactive configuration
• Order Agent exists over the whole business process
Inte
rnet
base
d C
onne
ctio
n
Source: Blecker/Graf (2004), o.S.
Figure 15: Distributed Production Planning and Control in the Actors approach
The decentralization of the production planning and control concept is also to be
reflected in the implementation of the production planning and control system. It is
also today that in decentralized structures central systems are used for the
planning. To solve this problem, a fit of the production planning and control
concept with the information system and the used techniques are necessary. The
use of Internet-based production environments support this fit, because Internet-
Technologies are inherently modular and therefore the resulting information
systems, in this case the production planning and control system. The actors
approach allows implementing the production planning and control system as a
multi-agent system, because the production system structure supports natively the
necessary separation of domains for the design of software agents.
Nonetheless, in practice managers have still to cope with the problem of huge amounts of orders. These are now executed in a decentralized, modularized, and agent-based environment. In mass customization, a direct interface to the configurator is appreciated. Ideally, every order from the configurator is directly submitted into the production planning and control system, where it is scheduled immediately. This is a complex task because many orders are different and therefore require different procedures. Therefore, a production planning and
Internet Technologies in Manufacturing - 68 -
control concept in with large amounts of heterogeneous orders should try to hold the customer order as a (abstract) unit and to route it through the necessary production steps and to exchange them between the agents. This abstract unit represents the planning and control efforts that are normally performed by the production planning and control. Therefore, the order unit has to know about the due dates and other important parameters. In our approach, we can interpret this unit as an actor that acts on behalf of the consumer. This leads the customer to become a „prosumer” (Piller 2001), which means the consumer takes over actions that in mass production are executed internally. The consumer creates an order and causes the creation of an information technological agent representing the order (unit). Due to acting on behalf of the consumer, this actor takes over the role of an agent in the information system.
Several mechanisms have been developed to implement such an approach. The necessary requirement is an interaction infrastructure, that allows multiple communication and coordination relationships, which are provided in Internet-based production environments. Similar approaches have been presented e.g. by the PABADIS project (Pabadis 2001), but on the shop floor level only, where the manufactured goods are represented as autonomous software agents and machines and resources as resource agents. We concentrated on a higher, managerial level. Through this approach a close connection to the configurator occurs. This leads to a seamless integration from the order entry to the field level. Through the ideal transaction conditions in the production environment the application of software agents enlarges the responsiveness and the planning accuracy. The complexity due to the high amount of orders and variants is reduced by the distribution of decision competences to the smaller production units. They have full information about customer orders and are able to operate autonomously to fulfill their tasks.
Internet Technologies in Manufacturing - 69 -
6 Conclusion
Recapitulating, we point out, that Internet-Technologies and the potential fields for
their applications in production processes evolve very rapidly. Partially, Internet-
Technologies the core part of the information infrastructure in manufacturing. This
trend will sustain in the future, with the result that Internet-Technologies become
the standard information technologies. Therefore, the intraorganizational
application of Internet-Technologies has to be considered in all managerial
decisions in operations.
We pointed out that an Internet-based hardware enables new approaches for the
design of the information architecture in manufacturing. The service-oriented
architectures as a direct consequence of modern Internet standards will
revolutionize at least parts of the information processing in manufacturing. As the
web-service technologies are very “young” there has to be conducted much
applied and ground research for a utilization of the whole potential. Several large
research projects led by the large system vendors, even with the focus on
manufacturing, promise many new products and technologies in the near future.
One of the most complex problems in manufacturing is production planning and
control. The generation of a at least approximately optimal plan or schedule is a
complex problem. For dynamic environments, there are no deterministic models
available that may solve the problem. Therefore, the worldwide research
community focuses on distributed problem solving, especially multi agent system.
We have shown, the in Internet-based environments lower the barriers for the
generation of multi agent systems for order management as well as for scheduling.
The presented framework has to be validated in future research.
Internet Technologies in Manufacturing - 70 -
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Bisher erschienene Diskussionspapiere der Universität Klagenfurt
9601 Dietrich Kropfberger Einsatz von Controlling- und Planungsinstrumenten in der Praxis – Ein Vergleich zwischen Österreich und Großbritannien 1996
9701 Hans-Joachim Bodenhöfer / Monika Riedel Bildung und Wirtschaftswachstum – Alte und neue Ansätze Februar 1997
9702 Hans-Joachim Bodenhöfer Kärnten 1945 - 1995. Wirtschaftspolitische Probleme und Leitlinien Juni 1997
9801 Michael Kosz On-site vs. Distant questioning: some empirical evidence from valuing recreation functions of city-near forests Mai 1998
9802 Michael Kosz The social context of valuing regional biodiversity Juli 1998
9803 Bernd Kaluza / Thorsten Blecker / Christian Bischof Strategic Management in Converging Industries November 1998 ISBN 3-85496-000-X
9804 Monika Riedel Selbstbeteiligungen in der Österreichischen Sozialen Krankenversicherung am Beispiel Kärntner Ärzteabrechnungen November 1998 ISBN 3-85496-001-8
9901 Doris Behrens / Jonathan Caulkins / Gernot Tragler / Gustav Feichtinger Optimal Control of Drug Epidemics: Prevent and Treat – But not at the Same Time? Juni 1999 ISBN 3-85496-002-6
9902 Doris Behrens / Jonathan Caulkins / Gernot Tragler / Gustav Feichtinger Why Present-Oriented Societies Undergo Cycles of Drug Epidemics Juli 1999 ISBN 3-85496-003-4
9903 Bernd Kaluza / Thorsten Blecker / Christian Bischof Networks - A Cooperative Approach to Environmental Management September 1999 ISBN 3-85496-004-2
9904 Bernd Kaluza / Thorsten Blecker Integration von Unternehmung ohne Grenzen und Supply Chain Management September 1999 ISBN 3-85496-005-0
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9905 Bernd Kaluza / Christian Bischof / Thorsten Blecker / Bernd Gotsche Einsatz und Entwicklungsperspektiven von betrieblichen Umweltinformations- und Umweltmanagementsystemen in der Kärntner Wirtschaft – theoretische Überlegungen und empirische Befunde Oktober 1999 ISBN 3-85496-006-9
9906 Michael Getzner Ecotourism, stakeholders, and regional development Oktober 1999 ISBN 3-85496-007-7
2000/01 Michael Getzner Economics of species and nature protection: empirical evidence from Austria Juni 2000 ISBN 3-85496-008-8
2000/02 Doris Behrens / Herbert Dawid Genetic Learning of Nash Equilibria in Illicit Drug Markets and Prerequisites for a Successful Crackdown August 2000 ISBN 3-85496-009-3
2001/01 Bernd Kaluza / Herwig Dullnig / Bernhard Goebel Überlegungen zur Konzeption eines Produktionsplanungs- und Recyclingplanungs- und -steuerungssystems für Verwertungs- und Entsorgungsnetzwerke Februar 2001 ISBN 3-85496-010-7
2001/02 Bernd Kaluza / Thorsten Blecker Konzept einer Produktionsplanung und -steuerung in der Unternehmung ohne Grenzen Juli 2001 ISBN 3-85496-011-5
2001/03 Paolo Rondo-Brovetto / Eva Krczal Analyse der Leistungsverteilung für Hals-, Nasen- und Ohrenkranke im Bundesland Kärnten Oktober 2001 ISBN 3-85496-012-3
2001/04 Sonja Grabner-Kräuter Die Bedeutung von Vertrauen im Electronic Commerce Dezember 2001 ISBN 3-85496-013-1
2001/05 Bernd Kaluza Controlling- und PPS-Systeme zur Lösung betriebswirtschaftlicher Probleme in Verwertungsnetzwerken Dezember 2001 ISBN 3-85496-014-X
2002/01 Michael Getzner Contributions to Cultural Economics: the case of Austria Januar 2002 ISBN 3-85496-015-8
2002/02 Birgit Friedl / Michael Getzner Environment and growth in a small open economy: an EKC case-study for Austrian CO2 emissions Januar 2002 ISBN 3-85496-016-6
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2002/03 Bernd Kaluza / Ralf-Jürgen Ostendorf Die zukünftige Bedeutung der Ökologie in der deutschen Automobilindustrie – eine kritische Analyse mit Hilfe der Szenario-Technik Dezember 2002 ISBN 3-85496-018-2
2003/01 Thorsten Blecker Web-based Manufacturing – Ansatz eines betriebswirtschaftlichen Konzepts einer Internetbasierten Produktion Februar 2003 ISBN 3-85496-019-0
2003/02 Thorsten Blecker Changes in Operations Management due to Internet-based Production Concepts – An Institution Economical Perspective Juni 2003 ISBN 3-85496-021-2
2003/03 Bernd Kaluza / Herwig Dullnig / Franz Malle Principal-Agent-Probleme in der Supply Chain – Problemanalyse und Diskussion von Lösungsvorschlägen Juli 2003 ISBN 3-85496-022-0
2003/04 Thorsten Blecker / Nizar Abdelkafi / Bernd Kaluza / Gerhard Friedrich Variety Steering Concept for Mass Customization August 2003 ISBN 3-85496-023-9
2003/05 Thorsten Blecker / Bernd Kaluza Forschung zu Produktionsstrategien – Ergebnisse und Entwicklungsperspektiven November 2003 ISBN 3-85496-024-7
2004/01 Thorsten Blecker / Bernd Kaluza Heterarchische Hierarchie: Ein Organisationsprinzip flexibler Produktionssysteme März 2004 ISBN 3-85496-025-5
Kontaktadresse:
Ass.-Prof. Dr. Herwig Winkler
Universität Klagenfurt Institut für Wirtschaftswissenschaften
Abteilung Produktions-, Logistik- und Umweltmanagement
Universitätsstraße 65 - 67 A - 9020 Klagenfurt
Tel.: +43-463-2700 – 4079 Fax.: +43-463-2700 – 4097
E-Mail: herwig.winkler@uni-klu.ac.at
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