View
65
Download
2
Category
Tags:
Preview:
DESCRIPTION
Principles of Engineering System Design. Dr T Asokan asok@iitm.ac.in. Dr T Asokan asok@iitm.ac.in 044-2257 4707. Principles of Engineering System Design. Lecture 4: System Design Process. What needs are we trying to fill? What is wrong with the current situation? - PowerPoint PPT Presentation
Citation preview
Principles of Principles of
Engineering System DesignEngineering System Design
Dr T Asokan
asok@iitm.ac.in
T Asokan
Principles of
Engineering System Design
Dr T Asokanasok@iitm.ac.in044-2257 4707
Lecture 4: System Design Process
• F ocus of S ystems E ngineering
– F rom O riginal Need
– T o F inal P roduct
• T he Whole S ys tem
• T he F ull S ys tem L ife C ycle
• F ocus of S ystems E ngineering
– F rom O riginal Need
– T o F inal P roduct
• T he Whole S ys tem
• T he F ull S ys tem L ife C ycle
Need
Operations Concept
Functional Requirements
System Architecture
Allocated Requirements
Detailed Design
Implementation
Test & Verification
NeedNeed
Operations ConceptOperations Concept
Functional RequirementsFunctional Requirements
System ArchitectureSystem Architecture
Allocated RequirementsAllocated Requirements
Detailed DesignDetailed Design
ImplementationImplementation
Test & VerificationTest & Verification
• F ocus of C omponent E ngineering
• O n Detailed Des ign
• And Implementation
• F ocus of C omponent E ngineering
• O n Detailed Des ign
• And Implementation
• What needs are we trying to fill?• What is wrong with the current s ituation?• Is the need clearly articulated?
• Who are the intended users?• How will they use our products?• How is this different from the present?
• What specific capability will we provide?• T o what level of detail?• Are element interfaces well defined?
• What is the overall plan of attack?• What elements make up the overall approach?• Are these complete, logical, and cons is tent?
• Which elements address which requirements?• Is the allocation appropriate?• Are there any unnecessary requirements?
• Are the details correct?• Do they meet the requirements?• Are the interfaces satisfied?
• Will the solution be satisfactory in terms of cost and schedule?
• C an we reuse existing pieces?
• What is our evidence of success?• Will the customer be happy?• Will the users ’ needs be met?
• What needs are we trying to fill?
• What is wrong with the current s ituation?
• Is the need clearly articulated?
• Who are the intended users?
• How will they use our products?
• How is this different from the present?
• What specific capability will we provide?
• To what level of detail?
• Are element interfaces well defined?
• What is the overall plan of attack?
• What elements make up the overall approach?
• Are these complete, logical, and cons is tent?
• Which elements address which requirements?
• Is the allocation appropriate?
• Are there any unnecessary requirements?
• Are the details correct?
• Do they meet the requirements?
• Are the interfaces satisfied?
• Will the solution be satisfactory in terms of cost and schedule?
• C an we reuse existing pieces?
• What is our evidence of success?
• Will the customer be happy?
• Will the users ’needs be met?
• F ocus of S ystems E ngineering
– F rom O rig inal Need
– T o F inal P roduct
• T he Whole S ystem
• T he F ull S ystem L ife C ycle
• F ocus of S ystems E ngineering
– F rom O rig inal Need
– T o F inal P roduct
• T he Whole S ystem
• T he F ull S ystem L ife C ycle
Need
Operations Concept
Functional Requirements
System Architecture
AllocatedRequirements
Detailed
Design
Implementation
Test & Verification
•F ocus of C omponent E ng ineering
•O n Detailed Des ign
•And Implementation
•F ocus of C omponent E ng ineering
•O n Detailed Des ign
•And Implementation
Six functions of Design Process
2. Develop the system functional architecture
1. Define system level design problem : Originating requirements development
3. Develop the system physical architecture
4. Develop the system operational architecture
5. Develop the interface architecture
6. Define the qualification system for the system
Development phase, manufacturing phase, deployment phase, training phase, operation or maintenance phase, refinement, retirement phase.
Life cycle
DefineRequirements
DefineRequirements
InvestigateAlternativesInvestigateAlternatives
Full-ScaleDesign
Full-ScaleDesign
ImplementationImplementationIntegration
& TestIntegration
& Test
Operation, Maintenance& Evaluation
Operation, Maintenance& Evaluation
Retirement,Disposal &
Replacement
Retirement,Disposal &
Replacement
The systemlife cycle
The systemlife cycle
DefineRequirements
DefineRequirements
InvestigateAlternativesInvestigateAlternatives
Full-ScaleDesign
Full-ScaleDesign
ImplementationImplementationIntegration
& TestIntegration
& Test
Operation, Maintenance& Evaluation
Operation, Maintenance& Evaluation
Retirement,Disposal &
Replacement
Retirement,Disposal &
Replacement
The systemThe systemlife cyclelife cycle
The systemThe systemlife cyclelife cycle
Define System Level Design Problem
• Operational Concept• External Systems• Originating Requirements• Objectives hierarchy• Documentation• Requirement management
1. Define System Level Design Problem
Major Input: Stake holders’ inputs
Major output: Originating requirements, Operational concept
• An operational concept is a vision for what the system is (in general terms). It is a statement of mission requirements, and a description of how the system will be used.
It includes:
•Information about how the system will be developed, operated and retired (from the perspective of the system’s stakeholders).
•A collection of scenarios.
•Systems interaction with other systems.
T Asokan ED309
Operational concepts for landing on the moon
T Asokan ED309
Operational Concept Scenario- Example: Passenger lift
Passengers (including mobility, hearing, visually challenged) request up service, receive feed back that their request was accepted, receive input that the elevator car is approaching, and then that an entry opportunity is available, enter elevator car, request floor, receive feedback that their request was accepted, receive feedback that the door is closing, receive feedback about what floor the elevator is stopping, receive feedback that an exit opportunity is available, and exit elevator with no physical impediments.
Scenario 1
Scenario 2
Scenario 3
Scenario 4
Scenario 5
Emergency situation
Fire
Auto-close
Breakdown
Overload
maintenance
T Asokan ED309
Scenario Description
Input/Output Trace Passenger ElevatorUp service request
feedback
Floor request
Exit opportunity
Input/output trace for scenario 1
T Asokan ED309
External Systems Diagram
It is the Model of the interaction of the system with other systems (external) in the relevant contexts, thus providing a definition of the system’s boundary in terms of the system’s inputs and outputs.
Purpose: Explicitly define the systems boundary and needed interfaces.
Systems/Mechanisms
1. Elevator System
2. Passengers
3. Maintenance personnel
4. Building
System Function
Provide elevator services
Request and use elevator services
Maintain elevator services
Provide structural support
T Asokan ED309
External Systems Diagram
Provide Elevator Services
Request Elevator Services
Use Elevator Services
Maintain Elevator Services
Provide structural support
PassengersElevator system
Maintenance Personnel
Building
Building regulations
T Asokan ED309
Objectives Hierarchy
• Stakeholders would be willing to pay to obtain increased performance on any of these objectives.
• Developed by defining the natural subsets of the fundamental objectives
The hierarchy of objectives that are important to the system’s stakeholders in a value sense.
• Usually has two to five levels. Additional information like value weights, value curves etc. are added for each objective.
• Acts as a corner stone for trade-off studies • To be developed for each phase of the life cycle of the system.
• An important tool in the decision making process
T Asokan ED309
T Asokan ED309
Requirements categoriesOriginating requirements (OR): Derived from operational needs, operational requirements are those top-level statements defined in language that is understandable to stakeholders, leaving substantial room for design flexibility.Derived requirementsDefined by system engineering team in engineering terms during the design process.
Mission requirements
Originating requirements
Implied RequirementsRequirements not specifically identified in the OR but can be inferred based upon the available information.
Emergent Requirements
System RequirementsComponent
Requirements
Configuration Item Requirements
Derived
requirements
Requirements that are not even hinted at in the OR but whose presence is made known by stakeholders later in the system engineering process.
Mission requirements
Originating requirements
System Requirements
Component Requirements
Configuration Item Requirements
Derived
requirements
Recommended