Journal of Intelligent Manufacturing (1999) 10, 245±250

Intelligent tracking in manufacturing

A L E X A N D E R B R E W E R and N A N C Y S LOA N

University of Oklahoma, Norman, Oklahoma, USA

T H O M A S L . L A N D E R S

University of Arkansas, Fayetteville, Arkansas, USA

Dynamic scheduling is an important new innovation in manufacturing and supply chain

management. However, the success of dynamic scheduling will depend on real-time information.

This paper describes intelligent tracking technologies that provide real-time information throughout

the supply chain to support keywords a logistics planning and execution.

Keywords: Intelligent tracking, RFID, virtual warehouse

Introduction

Intelligent tracking technologies (IT2) include global

positioning systems (GPS), geographic information

systems (GIS), wireless telecommunications, and

radio frequency identi®cation (RFID) as shown in

Fig. 1. Today, these technologies are both intelligent

and integrated.

Perhaps more than any other technology, intelligent

tracking has the potential to contribute to improve-

ments in manufacturing and to the entire supply chain.

From orders of raw materials and sub-assemblies

through product assembly, testing, and distribution,

intelligent tracking technologies offer opportunities

for increased ef®ciencies and improved customer

service.

Intelligent tracking implies that the information is

gathered automatically and improves a system by

reducing the time needed between value-added steps

and thus improves ef®ciency and cycle time. Devices

not only collect their own data, but they also are

capable of analyzing it and performing necessary

actions to a process autonomously.

For example, suppose an RFID reader is integrated

with a computer attached to a wireless telecommuni-

cations device. The result is a capability to read a tag

attached to a truck on a toll road and automatically bill

the carrier's account. If the truck is also out®tted with

GPS, then positional information may be transmitted

back to the carrier's home of®ce to enhance asset

management and customer service.

IT2 may be employed to improve the ef®ciency and

effectiveness of the supply chain. With the increasing

competitiveness and rising costs of transportation and

storage, service to the customer requires information

about operations status and decision tools to coordi-

nate the total supply chain.

Figure 2 illustrates the integrated supply chain.

Historically, the supply chain was controlled in a

sequential manner. Through IT2, point-of-sale trans-

actions are simultaneously routed to all stages of the

supply chain. Since the planning for all stages of the

supply chain is initiated concurrently, the coordina-

tion between elements is increased and the logistics

cycle time is reduced.

When RFID is linked to other members of the group

of intelligent tracking technologiesÐglobal posi-

tioning system, geographical information system,

and wireless telecommunicationÐthe potential for

improvements in service and ef®ciency can be

enhanced throughout the supply chain. A preliminary

introduction to these technologies is in order.

Global positioning systems (GPS) were ®rst

introduced in the United States as a defense initiative

in the 1970s. They are based on a constellation of 24

high-altitude satellites in orbit approximately 12,500

miles above the Earth. Ground-based equipment

includes the transceiver (a transmitter and receiver

0956-5515 # 1999 Kluwer Academic Publishers

combined in a single unit) which receives and decodes

information in the signals from the satellites. Through

triangulation calculations based on the position and

time off-set of four satellites, the latitude, longitude,

and altitude of the transceiver can be determined

(Fig. 3). Transceivers can be located on a variety of

items and are now commonly used in the trucking

industry.

A geographic information system (GIS) is a

computer-based mapping tool that translates the

location parameters from the GPS into the practical

information needed to determine a location (i.e.,

nearby cities, highway numbers, street names). The

databases are integrated with a graphical user inter-

face so the user can visually pinpoint a location.

Wireless telecommunications began in the 1980s

with the introduction of the cellular phone and are

now rapidly increasing in variety, in capability, and in

size of coverage areas. Wireless communications use

the radio portion of the electromagnetic spectrum, the

portion in the 3000 to 300 billion cycle range. Cellular

phones, perhaps the most common of the wireless

devices, occupy the range of 806 to 890 MHz.

With the advent of cellular phones, ground-based

networks of radio transmitters/receivers have sprung

up across the United States in an attempt to provide

nation-wide cellular coverage. An area is divided into

cells ranging in diameter from one to 20 miles

depending on the terrain and capacity demand. Each

cell is equipped with a radio transmitter/receiver and

has its own radio frequency in the 824 to 848 MHz

range. In a transition so rapid that it is imperceptible to

the user, calls are ``handed-off'' from one cell to

another by a monitoring and switching computer as

the caller moves from one cell to another. In 1998,

two major networks of low or medium orbit satellites

will be operational for telecommunications usage and

will decrease the cost of satellite cellular service while

providing world-wide coverage.

Although conventional cellular service employs

analog signals, digital technology is rapidly

increasing in use. New means of handling digital

data have been developed so that it can be more

rapidly and economically transmitted through better

utilization of the airwaves.

An RFID system integrates an antenna with

electronic circuitry to form a transponder that, when

polled by a remote interrogator, will echo back an

Fig. 2. Pull supply chain.

Fig. 1. Components of IT2.

246 Brewer, Sloan and Landers

identi®cation number. A wireless RFID system

provides the following bene®ts:

* Identi®cation at a distance* Continuous or intermittent tracking* Real-time control* Operations in a harsh environment* Hands-free operation* Versatile memory and processing requirements

Other forms of information may be added to the ID

number in the tag. Read/write memory is an option,

allowing dynamic information to be stored with the

associated asset being tracked. Varying degrees of

complexity inside the controller chip of the tag also

allow for error correction, longer read distance, and

security of the information.

RF technology has been successfully used in some

portions of the supply chain. Copperweld, a

Pittsburgh-based steel tubing and wire manufacturer,

has taken the ®rst steps toward RFID. They have

implemented an infrastructure of RF units to handle a

barcode-based inventory system. Through the use of a

contactless system to read a variety of barcodes, they

have managed to reduce the time needed to complete

their original tracking process by two thirds.

Currently, the system builds the manifest of outgoing

goods by simply scanning a product's barcode and

entering an amount. Future plans include the use of

this system in their receiving department as well

(Copperweld, 1995).

The United States Postal service uses RFID to track

cycle times in their sortation centers. Working with

the RFID supplier, a new tag speci®cation was created

so that the tag would be the same size as a normal post

card. The post card is introduced into the system by

`mailing' it to someone. Antennas are strategically

setup in the centers to keep track of the tag as it moves

around the facility. When the tag reaches its

destination, the information on its path is tabulated

and used to assess the ¯ow of mail through the postal

system (Brewer and Landers, 1997)

Wacker Chemitronik in Berghausen, Germany uses

Fig. 3. GPS satellite system.

Intelligent tracking 247

TIRIS to achieve a zero-fault production process for

silicon wafer manufacturing. RFID tags are attached

to plastic trays that hold the wafers. A comprehensive

automation system called CarMas (Carrier

Management System) from the company HERMOS,

collects data as the trays go through various process

steps. Nine RFID read points are included on each

etching machine. Every step of the process is tracked

and managed. This process now only requires one

operator and eliminates all faults. Since the produc-

tion environment includes high temperatures and

harsh chemicals, the RFID tags must be reliable and

durable (TIRIS News, 1996)

BMW and Vauxhall use RFID tags to enable

accurate customization of individual customer

orders. A read/write smart tag is programmed with

the customer order. The tag is then attached to and

travels with the car during the production process.

This tracking ensures that the car is manufactured

with the correct color, model, interior, and any other

option the customer speci®es. Some of the major

advantages cited for this system are:

* Read without direct line of sight.* Reprogrammed to re¯ect different requirements.* Integrated into a complete system.* Reused at the end of assembly.* Used under harsh conditions because they are

maintenance-free and battery-free (Brewer and

Landers, 1997).

United Biscuits attaches RFID transponders to the

stainless steel carts, which are used to carry material

throughout the processing facility. Raw material and

®nished products are tracked as they travel through

the entire plant. The goals of the system were to

improve stock management, increase control over

material usage, and improve product trace-ability and

reporting. The factory uses the system to track bin

movement from initial weighing through preparation,

mixing, and baking. This ensures that the correct bin

is in the correct location throughout the process. Since

the tags are virtually maintenance free, the reliability

of the system is very high (TIRIS News, 1996)

Intelligent tracking in the supply chain

A variety of wireless options, such as RFID, may be

combined with a GPS to provide detailed information

about materials in transit. Table 1 identi®es potential

data and their uses. Such data include expected time

of arrival and perhaps the load manifest, depending on

the capabilities of tracking utilized. With this

information about an in-bound order for raw

materials, the manufacturer can assign a truck to the

correct dock and schedule unloading and manpower

requirements. The event times can thus be more

accurately determined.

Further, the information obtained by the hybrid

RFID/GPS system can then be combined with a

production scheduling algorithm on a shop ¯oor. The

production directives can be changed real-time in

response to information obtained from earlier in the

supply chain. Production quotas can be changed based

on the availability or quality of raw materials in

transit.

Table 1. (Sloan et al., 1997)

Feature Function

Location and identi®cation More ef®cient load assignment, routing, and dispatching; monitor status of

shipment; better emergency response; greater security; decreased insurance

costs for carrier and for shipper; better match of equipment type and need

Expected time of arrival (ETA) Assignment to correct dock; scheduling of unloading; better customer service

Load manifest Location and ETA of a particular shipment item; tracking hazardous cargo;

dedication of containers to hazardous cargo; take advantage of

postponement transportation and merge-in-transit opportunities

Engine parameters Trouble-shooting and maintenance scheduling; prevention of breakdowns;

safety considerations

Breakdown or emergency Faster response time; greater security for driver and load

Bill of lading information and con®rmation Instant invoicing

Document imaging or FAX capability Con®rmation of licensure, fees paid, etc.

248 Brewer, Sloan and Landers

Two relatively new concepts which can be more

easily implemented as a result of tracking

technologies are postponement transportation and

merge-in-transit. With postponement transportation,

a shipment that is not tied to a speci®c order is

dispatched in a general direction, and when an

order occurs, the shipment is then routed to the

proper destination. Merge-in-transit involves com-

bining the various segments of an order at a

common site, such as a truck depot or distribution

center, so the total order can be delivered as a

whole to the customer site. Merge-in-transit may

also include some assembly en route to the ®nal

destination. Intelligent tracking can also expedite

the ¯ow through customs gates, thus decreasing

delivery times.

The utilization of real-time data can provide

instantaneous decision-making responses to varia-

tions in the supply chain. Communication throughout

the supply chain is of foremost importance in order for

decision-making to be truly responsive to events.

Supply chain management software focuses on

matching up the supply and demand portions of a

business. The software is usually based on forecasting

methods for demand planning, production planning,

and scheduling. The modeling, problem-solving, and

optimization techniques include time-series analysis,

linear programming, mixed integer programming, and

simulation. Software suppliers include Manugistics,

Numetrix, i2 Technologies, and Chesapeake Decision

Sciences (Hicks, 1997).

Optimization tools focus on transportation resource

optimization, vehicle routing and scheduling, inven-

tory allocation, and manufacturing scheduling

optimization. The software utilizes operations

research and mathematical techniques to model and

solve speci®c operations issues. These techniques

include linear programming, mixed integer program-

ming, optimization and network modeling, and

simulation. Software suppliers include Red Pepper

Software Co., i2 Technologies, and CAPS Logistics

(Hicks, 1997).

RFID pilot test in manufacturing

The usefulness of RFID in manufacturing is being

assessed by The Logistics Institute at the University of

Arkansas. A pilot study of TIRIS technology was

completed at an electronics manufacturing facility in

November 1997. The purpose of the study was to

assess (1) the feasibility of the technology as a tool for

real-time shop ¯oor control and (2) the role of an

RFID integrator.

In this application of RFID, small printed circuit

boards were tracked. Each set of boards of a particular

type, or lot, was identi®ed by a unique batch number.

Each lot could contain one or more boards. The board

itself was stored in a small tote, measuring approxi-

mately 8 inches wide by 12 inches long by 1 inch

deep. Multiple boards could be placed in each tote if

they were in the same lot. As the boards went through

the manufacturing process of adding parts, inspection,

testing, and conformal coating. Boards could be split

off of the main lot if they were faulty or required

special attention. In this test, only three types of

boards were tracked.

One antenna was placed at each of the four

workstations. The RFID reader, stationed remotely

from the antennas, polled each of the four

antennas once per second, for a total of four

potential reads per second. Hardware and software

limited the RFID reader to only four reads per

second. It was the responsibility of each worker to

pass the RFID tag, attached to an accompanying

paperwork folder that was unique to each lot, by

the antenna in that area. In this way, the times

when the lot entered the workstation and when it

left could be tracked.

Though small scale, consisting of only two readers

and four antennas, the study was a good example of

the complexities of RFID technology in practice.

Among other considerations, read range, tag presenta-

tion, and ambient conditions were taken into account

during the study. One of the primary hurdles in the

study was the participation of workers in the shop. As

in any new technology, it is important to stress that the

technology is being installed to help the workers and

improve productivity, not to reduce jobs or increase

workload.

Preliminary results indicate that, due to the

complexities of RFID technology, a system integrator

is recommended. In so far as the improvement of the

work center itself, algorithms are being developed to

mesh the output of the RFID system into the existing

systems of the work center, to better improve process

¯ow and scheduling of the workers.

In the tasks of designing the system, developing the

software, and installing the hardware and software of

the system, speci®c knowledge is required in each

Intelligent tracking 249

area. Making the various components of the system

work together correctly can be considered an art. The

full results of this research will be published in a

subsequent article.

Conclusions

The real innovation in RFID is not in the technology

itself, but in its application in real-world situations.

The end goal of any project, such as introducing

RFID, Bar-code, or Data-matrix into an already-

existing system, must be to reduce cost. Reduction of

waste, production cycle time, other non-value added

time, or inventory is the purpose of a new technology,

not the introduction of the technology itself.

Conversely, innovation could be considered as

making a decision not to upgrade to a new technology.

The introduction of a new program to drive existing

technology can have a large effect on the workings of

an existing system as well. New real-time algorithms

could draw statistical data from the output of existing

hardware to drive a real-time production control

program just as easily as upgrading the entire

infrastructure to a new technology.

References

Brewer, A. and Landers, T. (1997) Radio FrequencyIdenti®cation: A Survey and Assessment of theTechnology, University of Arkansas Department of

Industrial Engineering Technical Report.

Copperweld Turns to Mobility on the Manufacturing Floor,

(1995) Industrial Engineering, 27.

Flynn, L. J. (1996) Post Of®ces Using Radio-ID Tags to

Monitor Flow of Mail, The New York TimesCyberTimes.

Hicks, Donald A. (1997) The Manager's Guide to Supply

Chain and Logistics Problem-Solving Tools and

Techniques: Tools, Companies, and Industries, IIESolutions, 29(10).

Sloan, Nancy, Carikcioglu, I., Landers T. and Taylor, G. D.

(1997) Intelligent Tracking Technologies for theTrucking Industry, University of Arkansas

Department of Industrial Engineering Technical

Report.

TIRIS News (1996), (16).

250 Brewer, Sloan and Landers