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Lecture 1: Introduction. Content. Course objectives Systems Engineering (SE) definitions Benefits of SE A Universal Ontology for SE System, Function, and Concept. Course Objectives. Study about systems and their development: How to analyze systems How to model systems - PowerPoint PPT Presentation
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Lecture 1 – Introduction Prof. Dov Dori
Methodologies in Systems Development –
Model-Based Systems Engineering097230 – Spring 2011
Lecturer: Prof. Dov Dori TIDES Pedagogical Advisors:
The William Davidson Facultyof Industrial Engineering and Management
Lecture 1: Introduction
Lecture 1 – Introduction Prof. Dov Dori
Content
2
Course objectives Systems Engineering (SE) definitions Benefits of SE A Universal Ontology for SE System, Function, and Concept
Lecture 1 – Introduction Prof. Dov Dori3
Course Objectives Study about systems and their development:
How to analyze systems How to model systems How to architect systems How to design systems How to test systems
This is a course about How to think, not What to think
Focus: Model-Based Systems Engineering –MBSE Via a critical review of OPM Second Edition book
Lecture 1 – Introduction Prof. Dov Dori4
Systems Engineering Defined
INCOSE – International Council on Systems Engineering Systems Engineering Handbook
Lecture 1 – Introduction Prof. Dov Dori5
What is Systems Engineering ?
Systems Engineering (SE) is a comprehensive approach to the development of any complex, multidisciplinary system.
The quality of the system resulting from SE impacts the cost and value of the entire project.
Lecture 1 – Introduction Prof. Dov Dori6
More Systems Engineering Definitions
“The top level process of engineering a system to meet overall requirements.”www.tso.co.uk/demo/itil2/cd/content/ss/ss_apdx_a_02.htm
“The application of engineering to solutions of a complete problem in its full environment by systematic assembly and matching of parts in the context of the lifetime use of the system.”www.ichnet.org/glossary.htm
Engineering Systems At MIThttp://techtv.mit.edu/collections/esd/videos/9379-the-engineering-systems-division-at-mit
Lecture 1 – Introduction Prof. Dov Dori7
Yet another SE Definition “Systems engineering is the branch of engineering concerned with the development of large and complex systems.Systems engineering focuses on the real-world goals for, services provided by, and constraints on such systems; the precise specification of system structure and behavior, and the implementation of these specifications; the activities required in order to develop an assurance that the specifications and real-world goals have been met; the evolution of such systems over time and across system families. It is also concerned with the processes, methods and tools for the development of systems in an economic and timely manner.”http://www.mssl.ucl.ac.uk/syseng/pages/sedef.html
Lecture 1 – Introduction Prof. Dov Dori8
Engineering Systems At MIT
Related to systems engineering, which is an important profession and practice, engineering systems is a field of scholarship that includes systems engineering as well as a broader set of disciplines. Engineering systems has an added focus on social, environmental, technological, and political contexts.
Watch some of the 7 min. video:
http://techtv.mit.edu/collections/esd/videos/9379-the-engineering-systems-division-at-mit
Lecture 1 – Introduction Prof. Dov Dori9
SE and Engineering Systems in Context
Societycountry
EngineeringSystems Conceptual modeling
is not limited to any of the borders on the left.
It can be applied to systems in any domain and at any level of complexity.
Lecture 1 – Introduction Prof. Dov Dori10
System Engineering Phases
Accounts for~15% of the Development
Budget
Systems Engineering encompasses:• Requirements engineering• System architecture • Subsystem integration design• System testing design • Project oversight & management
SYSTEMENGINEERING
DETAILEDDESIGN
PRODUCTIONINTEGRATION TEST
Software Design
Mechanics Design
Electronics Design
Lecture 1 – Introduction Prof. Dov Dori11
Much of the system or product’s value, cost and risk are determined here.
Mistakes at this stage • affect all downstream phases,• are the most difficult and costly to correct,• determine project cost, timetable, overall success
TESTSYSTEMDESIGN
DETAILEDDESIGN
PRODUCTIONINTEGRATION
Why is Systems Engineering important?
Lecture 1 – Introduction Prof. Dov Dori12
Potential benefits of Systems Engineering
Better system quality and value Lower cost Shorter time-to-market
SYSTEMDESIGN
DETAILDESIGN
PRODUCTIONINTEGRATION TEST
Traditional Design
Time
Risk
SavedTime &
Cost“System Thinking” Design Time
Risk
Lecture 1 – Introduction Prof. Dov Dori13
Pre-Cost Commitment Investment vs. Total Cost Growth
% C
OST
GR
OW
THO
VER
TO
TAL
ESTI
MAT
E
Source Werner GruhlNASA Comptroller’s Office
Impact of “Front-End” Investment
2% 4% 6% 8% 10% 12%
IUE
140%
120%
100%
80%
60%
40%
20%
0%
-20%
COBE
ISEE
ERBE
Pre-Cost Commitment Investment vs. Total Cost Growth
% C
OST
GR
OW
THO
VER
TO
TAL
ESTI
MAT
E
Source Werner GruhlNASA Comptroller’s Office
Impact of “Front-End” Investment
2% 4% 6% 8% 10% 12%
IUE
140%
120%
100%
80%
60%
40%
20%
0%
-20%
COBE
ISEE
ERBE
Pre-Cost Commitment Investment vs. Total Cost Growth
% C
OST
GR
OW
THO
VER
TO
TAL
ESTI
MAT
E
Source Werner GruhlNASA Comptroller’s Office
Impact of “Front-End” Investment
2% 4% 6% 8% 10% 12%
IUE
140%
120%
100%
80%
60%
40%
20%
0%
-20%
COBE
ISEE
ERBE
Pre-Cost Commitment Investment vs. Total Cost Growth
% C
OST
GR
OW
THO
VER
TO
TAL
ESTI
MAT
E
Source Werner GruhlNASA Comptroller’s Office
Impact of “Front-End” Investment
2% 4% 6% 8% 10% 12%
IUE
140%
120%
100%
80%
60%
40%
20%
0%
-20%
COBE
ISEE
ERBE
% Investment inSystem Engineering Effort (SEE)
NASA Tracking 1980s
Total Program Overrun32 NASA Programs
Lecture 1 – Introduction Prof. Dov Dori14
NEED
Conceptual-Preliminary
Design
DetailedDesign and
Development
ConstructionAnd/or
Production
System Use,Phase out, and Disposal
%
25
50
75
100
Commitment to Technology,Configuration, Performance, Cost, etc.
Cost Incurred
System-Specific Knowledge
Ease of Change
Commitment, System-Specific Knowledge, and Cost
Systems Engineering is important early in a program to influence the design, when incurred costs are low and design changes are easy.
Time-Phased Sensitivity of SE to Total System Lifecycle Cost
Lecture 1 – Introduction Prof. Dov Dori15
Conceptual System Design Phase
PreliminarySystem Design
Phase
Detailed Design and Development
Phase
Desig
n In
fluen
ce
High
LowSystems Design and Development Progress
Individual Design Disciplines
Systems Engineering
Concept and Technology Development
Lecture 1 – Introduction Prof. Dov Dori16
Clicker Question
What statement is incorrect?1. Systems Engineering is multi- and interdisciplinary.
2. Early discovery of design errors saves expenses down the road.
3. Systems Engineering deals only with requirements definitions.
4. Focus on individual disciplines increases as we move from conceptual to detailed design.
Lecture 1 – Introduction Prof. Dov Dori17
Interim ConclusionsSystems Engineering effort improves development
qualityCost & schedule improvedHypothesis is supported by the data
Optimum Systems Engineering effort is 10-15%Matches data from NASA projectsCost & schedule overruns are minimized
Systems Engineering must have its ontology and modeling language!Like any engineering discipline, SE must be based on
solid foundations of a modeling language
Lecture 1 – Introduction Prof. Dov Dori18
Questions?
Lecture 1 – Introduction Prof. Dov Dori19
Benefit and Cost
Benefit is anything that increases the physical or mental well-being of a human or a group of humans.
Benefit usually come at some cost.
Cost is the sum of resources and efforts needed to extract or gain benefit.
Lecture 1 – Introduction Prof. Dov Dori20
Value
Value is benefit at a cost. Value = Benefit – Cost If the benefit is larger than the cost, then the value is
positive and the cost is worth spending (and vice versa).
Value is subjective – it is in the eyes of the beholder, who is the beneficiary.
Some processes provide value to some beneficiaries.
Such processes are called functions.
Lecture 1 – Introduction Prof. Dov Dori21
Function
A function is a process that delivers value to a beneficiary.
Function is also an attribute of an object, which describes: the rationale behind the existence of that object the intent for which it was built the purpose for which it exists the goal it serves, or the set of phenomena or behaviors it exhibits.
Lecture 1 – Introduction Prof. Dov Dori22
Examples of Functions
1. Function: Print a document.2. Function: Frame a picture.3. Function: Show the time of day.4. Function: Cross a river.5. Function: Carry at least 2000 tons of wheat
every week across a distance of 400 Km.6. Function: Protect a large civilian passenger
aircraft from a terrorist missile attack.
Lecture 1 – Introduction Prof. Dov Dori23
Phrasing a Function as a Process
Given a function, we convert it to a process phrasing by using the gerund form at the end of the process name.
Example: Function: Show the time of day. Process: Time of Day Showing
Continue the example with these functions 1. Function: Cross a river.2. Function: Carry at least 2000 tons of wheat every week
across a distance of 400 Km.3. Function: Protect a large civilian passenger aircraft from
a terrorist missile attack.
Lecture 1 – Introduction Prof. Dov Dori24
Exercise: Phrasing a Function as a Process
Given a function, convert it to a process phrasing by using the gerund form at the end of the process name.Function: Cross a river. Process: Function: Carry at least 2000 tons of wheat every
week across a distance of 400 Km. Process: Function: Protect a large civilian passenger aircraft
from a terrorist missile attack. Process:
Lecture 1 – Introduction Prof. Dov Dori25
Exercise
Phrase three functions and their corresponding processes Function: Process: Function: Process: Function: Protect a large civilian passenger
aircraft from a terrorist missile attack. Process:
Lecture 1 – Introduction Prof. Dov Dori26
System
Performing a function (and extracting value) requires the operation of some object.
That object is called system.
A system is a function-carrying object.The function is the main process the system performs.
Lecture 1 – Introduction Prof. Dov Dori27
Stakeholders: Beneficiary, User, OwnerBeneficiary is the agent (human or group
of humans) who benefits from the system’s operation
User, or operator, is the agent who uses and operates the system.
Owner is the agent who orders, acquires, and owns the system.
In small systems, the three are the same.In large systems, they may be different.
Lecture 1 – Introduction Prof. Dov Dori28
For which of the following systems the Beneficiary, User, and Owner are different?1. Scissors2. Car3. Lightweight rail4. National Missile Defense System
Clicker Question
Lecture 1 – Introduction Prof. Dov Dori29
Preliminary Stakeholders Model Agent: A human or group of humans who handle the process and
enable it but are not affected by it. Denoted by the “black lollipop”. The double arrow is the effect link – denotes that the process
changes the object’s state. Why is the model not quite correct?
Lecture 1 – Introduction Prof. Dov Dori30
Other Stakeholders
Supplier, Contractor, Subcontractors
Government, Legislator
The Public
Specific systems have specific stakeholders.Any more stakeholders? For what systems?
Lecture 1 – Introduction Prof. Dov Dori31
The Three Main System Aspects
Natural and artificial systems alike exhibit three major aspects: Function: why is the system built; what value is it
expected to create?Structure: what are the system’s parts; how are
they combined to provide the function?Behavior: how does the system operate; how
does it change over time?
Lecture 1 – Introduction Prof. Dov Dori32
The Concept Behind a System
Function pertains to the goal the system is designed for.
In order to function (and provide value) the system must operate based on some idea.
This idea often makes use of the laws of nature and logic in some clever way.
Concept is the idea or working principles underlying the functioning of the system.
Lecture 1 – Introduction Prof. Dov Dori33
Examples for System Concepts
Given a function, propose at least two concepts for the system to be architected.
1. Function: Show the time of day.2. Function: Cross a river from one bank to the
other.3. Function: Carry at least 2000 tons of wheat
every week across a distance of 400 Km.4. Function: Protect a large civilian passenger
aircraft from a terrorist missile attack.
Lecture 1 – Introduction Prof. Dov Dori34
System Architecture
System architecture is the overall system’s structure-behavior combination, which enables it to attain its function while embodying the architect's concept. In terms of architecture, concept is the system
architect’s strategy for a system’s architecture. Examples:
Time Keeping system River Crossing system
Lecture 1 – Introduction Prof. Dov Dori35
Product vs. Service Product is a system that is produced by an entity
with the intent of selling it to another entity for a profit. It is a system that has a commercial value to its
manufacturer.
Service is a function provided by an entity to another entity for a profit. It is a function that has a commercial value to its providerThe provided uses a system to provide the service.
Lecture 1 – Introduction Prof. Dov Dori36
Clicker Question
What statement is incorrect?1. System architecture combines structure and behavior
to provide function.
2. Every function has exactly one concept by which it can be achieved.
3. Product is to object what service it to process.
4. For simple systems or products, the owner, user and beneficiary are one and the same.
Lecture 1 – Introduction Prof. Dov Dori37
Questions?
Lecture 1 – Introduction Prof. Dov Dori38
Model: An Abstraction
A model is an abstraction of a system, aimed at understanding, communicating, explaining, or designing aspects of interest of that system.
Modeling approaches and methods: Natural Language Mathematics Graphics-based: sketch, map, drawing … Physical …
Lecture 1 – Introduction Prof. Dov Dori39
A Language for Systems Engineering
Systems engineering is the youngest engineering discipline
Like any field of engineering, systems engineering needs to have a language for accurately and unambiguously specifying the system of interest.
In this language, system engineers and other stakeholders should be able to express the design concepts of the system under development in a concise and easily communicable way.
Lecture 1 – Introduction Prof. Dov Dori40
Things, and links that connect them, are the elements of any system
Just two types of things:
Object, which can be possibly stateful – a
Stateful Object – Object with States
Process Each thing stands alone as a concept in its own right Things and states are called entities. A Link connects two entities. Links and things are elements
A Universal Ontology for
Systems Science & Engineering
Lecture 1 – Introduction Prof. Dov Dori41
Object
An object is a thing that exists or can exist physically or informatically. The object's existence can be physical or
informatical (or conceptual, or logical). It can be as simple as a block of ice or a record
in a file, or as complex as an organization, a human brain, or a galaxy.
Lecture 1 – Introduction Prof. Dov Dori42
Object NamingObject naming is simple—it is the noun. It can be a phrases with more than one word:
Apple Cake Automobile Crash – note that every word is capitalized
The object singularity OPM principle:A name of an object must be singular. Plural has to be converted to singular. Convert a plural object to singular by adding the word "Set"
Ingredients (e.g., of a Cake) becomes Ingredients Set. "Set" is an OPM reserved word used for loops and iterations
on the set members.
Lecture 1 – Introduction Prof. Dov Dori43
Object State
A state is a possible situation at which an object can be, or a value it can assume, for some positive amount of time. A state does not stand alone It has a meaning only within, and in the context of, an object. Examples:
States of the object Organization can be private or public States of the object Record can be locked or unlocked
State names are not capitalized Exercise: Model these examples
Lecture 1 – Introduction Prof. Dov Dori44
Transformation
Transformation is the creation (generation, construction) of
an object or consumption (elimination, destruction)
of an object or changing the state of an object.
Transformation takes a positive amount of time.
Lecture 1 – Introduction Prof. Dov Dori45
Process
A process is a thing that transforms an object.In other words:
A process is a pattern of object transformation. By definition, a process must be associated with
at least one object, the one which the process transforms.
For exampleFreezing is a process that creates an Ice Block Melting is a process that destroys an Ice Block
Exercise: Model these assertions.
Lecture 1 – Introduction Prof. Dov Dori46
Process Naming The gerund process naming modeA process name is a phrase whose last word should be the gerund form of a verb, a verb with the "ing" suffix. If there are several choices, such as in Construction vs. Constructing, the
latter is preferable. This naming convention has two advantages
clarifies the dynamic nature of the process as a thing that happens rather than a thing that exists.
The ing suffix enables automated detection of processes. An object name can precede the gerund.
In Engine Igniting, the process Igniting transforms the object Engine by changing its state from shut down to running.
Adding an object before the process qualifies the process. For example, Wall Painting, Roof Painting , and Car Painting are similar yet different
processes.
Lecture 1 – Introduction Prof. Dov Dori47
Gerund process naming mode versions
The verb version: the gerund form of the verb verb + ing, as in Making or Crossing.
The noun-verb version: noun + verb + ing, as in Cake Making or River Crossing.
The adjective-verb version: adjective + verb + ing, as in Quick Making or Assisted Crossing.
The adjective-noun-verb version: a concatenation of an adjective with a noun with the gerund adjective + verb + ing, as in Quick Cake Making or Assisted River Crossing.
In these examples, the adjective qualifies the process (the gerund, which is a noun).
However it can also qualify the object (the noun), as in Sweet Cake Making or Wide River Crossing.
Where do we place the adjective of the process if we want also an adjective for the object? Quick Sweet Cake Making
Lecture 1 – Introduction Prof. Dov Dori48
The Emergence of MBSE
Systematic specification, analysis, design and implementation of new systems and products are becoming ever more challenging and demanding
Contradicting requirements of shorter time-to-market, rising quality, and lower cost are on the rise.
These realizations have provided the basis for Model-
Based Systems Engineering (MBSE) as a foundational field of study within systems engineering.
Lecture 1 – Introduction Prof. Dov Dori49
MBSE MethodologyMBSE calls for the development of a comprehensive
methodology, capable of tackling the mounting challenges that the evolution of new systems and products poses.
An MBSE methodology is a collection of related processes, methods, and tools that support systems engineering.
Modeling is a foundational engineering activity in an MBSE methodology.
The evolving model resulting from this activity is a central infrastructural entity
The model supports systems development, evolution, and lifecycle in a “model-based” or “model-driven” context.
Lecture 1 – Introduction Prof. Dov Dori50
Model Based Systems Engineering Benefits
• Shared understanding of system requirements and design– Validation of requirements– Common basis for analysis and design– Identification of risks
• Basis for managing complex system development– Separation of concerns via multiple views of an integrated model– Support for traceability through hierarchical system models– Facilitation of impact analysis of requirements and design changes– Support for incremental development & evolutionary acquisition
• Improved design quality– Reduced errors and ambiguity early on– More complete and consistent representation
Lecture 1 – Introduction Prof. Dov Dori51
Conceptual Modeling
Central to the MBSE approach is the activity of conceptual modeling:the creation of a model or inter-related models or views in
some formal languageThe model specifies at various levels of detail, and from
various viewpoints, how a system is structured and how it behaves in order for it to deliver its intended function.
Let us examine an OPM model of a generic product lifecycle engineering system.
Lecture 1 – Introduction Prof. Dov Dori52
The System Diagram (SD) of
Product Lifecycle Engineering
Lecture 1 – Introduction Prof. Dov Dori53
Zooming into Product Lifecycle Engineering
Lecture 1 – Introduction Prof. Dov Dori54
The System Map: A Tree View
Lecture 1 – Introduction Prof. Dov Dori55
The System Map: All the OPDs in one View
Lecture 1 – Introduction Prof. Dov Dori56
Zooming into the Details of Design
Lecture 1 – Introduction Prof. Dov Dori57
Zooming into the Details of Manufacturing
Lecture 1 – Introduction Prof. Dov Dori58
Zooming into Initial Shaping within Making
Lecture 1 – Introduction Prof. Dov Dori59
Zooming into Software Module Developing within Making
Lecture 1 – Introduction Prof. Dov Dori60
Zooming into Assembly & Testing
Lecture 1 – Introduction Prof. Dov Dori61
Zooming into Commerce
Lecture 1 – Introduction Prof. Dov Dori62
Zooming into Use & Service
Lecture 1 – Introduction Prof. Dov Dori63
SD1.4 - End Of Life in-zoomed
Product is physical.
Zooming into End-of-Life
Lecture 1 – Introduction Prof. Dov Dori64
Main Advantages of Systems Engineering with OPM
Clear, intuitive, consistent graphical and textual communication language among all stakeholders.
A comprehensible model of the systemThe model evolves throughout the system lifecycle. System animation and simulation for design level
debugging. Preservation of actionable knowledge for effective
maintenance and future generations development via OPCAT’s built-in evolution mechanism.
Lecture 1 – Introduction Prof. Dov Dori65
Summary
Product and system lifecycle ontology is needed as a common language among the various stakeholders.
OPM offers a foundational, domain-independent ontology that is based on the notion of stateful objects and processes that transform them.
Using OPM, we have constructed a model-driven ontology for products and systems throughout their lives.