Principles of Engineering System Design

1. Principles of Engineering System Design Dr T Asokan asok@iitm.ac.in

2. INTRODUCTION TO SYSTEMS DESIGN FUNCTIONAL ARCHITECTURE Dr T Asokan asok@iitm.ac.in xxxx 4707 T Asokan ED309

3. Operational Views Functional View Physical View • Defines allocated resources (hardware and software). Shows the interconnections between the resources. • Usually described by: • Physical Block Diagrams • Physical Interface Definitions • Defines the capabilities, the services, or the functions provided by the system. • Shows the messages / data between functions • Usually described by: • IDEF0 Diagrams • Functional Flow Block Diagrams • N2 Diagrams Shows how the operator will use the system. Shows inputs and outputs to users and other systems. Usually described by: • Operational Concept • Context Diagram • Use Case Scenarios • Sequence Diagrams • High Level Data Model

4. Six functions of Design Process • Define System Level Design Problem : - • Originating requirements development • 2. Develop the system functional architecture • 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

5. A function of a system is a statement of a clear reproducible relationship between the available input and the desired output of a system, independent of any form. Output Input Product Function Need for Functional Modeling Logical way of carrying forward customer needs Clear thinking at the concept level Design repository Design for Six Sigma design – easy identification of weakness and rectification T Asokan ED309

6. TERMINOLOGY FOR FUNCTIONAL ARCHITECTURE System Modeis defined to be a distinct operating capability of the system during which some or all of the system’s functions may be performed to a full or limited degree. System state:A static snapshot of the set of metrics or variables needed to describe fully the systems capabilities to perform the system functions. It is the values of state variables at a specific point in time. T Asokan ED309

7. A functionof a system is a statement of a clear reproducible relationship between the available input and the desired output of a system, independent of any form. Input Output Product Function A functionalityis a set of functions that is required to produce a specific output. T Asokan ED309

8. FUNCTIONAL ARCHITECTURE • A functional architecture can be defined as a logical architecture that defines what the system must do, a decomposition of the systems top-level function. • Logical model of functional decomposition • Flow of inputs and outputs • Mapping of requirements to functions Requirements Operational Concept Simple functionalities for O.C Draft and evaluate Functional model Complete functional and data models Trace I/O requirements to functions and items System level functional architecture T Asokan ED309

10. FUNCTIONAL ARCHITECTURE Decomposition (top-down) Partition system function a level at a time Need sound definition of all inputs & outputs Composition (bottom-up) Define many functionalities (bottom-level functions) Synthesize functional hierarchy from many bottom-level functions Use both: The best solution T Asokan ED309

11. When it comes to partitioning a function, there are many choices: • Use operating modes • Use inputs & controls • Use Hatley-Pirbhai template

12. Process Model Input Output Processing Processing Control Model Maintenance, Self-Test, and Redundancy Management Processing Partitioning Functions: Hately-Pirbhai template User Interface Processing

13. Hately-Pirbhai template: Example Accept passenger requests and provide feedback Move passengers between floors Process level, fire, security etc. information Conversion of analogue to digital etc. Control elevator cars Enable effective maintenance and services

14. Input Output Processing Processing Maintenance, Self-Test, andRedundancy ManagementProcessing Partitioning Functions: Hately-Pirbhai template User Interface Processing ProcessModel Control Model Accept passenger request and provide feedback Move passengers between floors Process level, Fire, security etc. information. Conversion Of Analouge to digital etc. Control elevator cars Enable effective maintenance And services

15. Accept passenger request and provide feedback Move passengers between floors Process Conversion level, Of Fire, Analouge Control elevator cars security etc. to information. digital etc. Enable effective maintenance And services

16. User Interface Processing Process Model Input Input Output Output Control Model Processing Processing Processing Processing Maintenance Maintenance Self Self - - Test Test , , , , and and Redundancy Redundancy Management Management Processing Processing

17. Provide data entry /OP facilities Accept passenger request and provide feedback Process user input data ( convert to machine format) Conversion of OP data to useful signals Generate Control commands Provide fault tolerance and maintenance functions Accept passenger request and provide feedback Move passengers between floors Process level, Fire, security etc. information. Conversion Of Analouge to digital etc. Control elevator cars Enable effective maintenance And services

18. Accept passenger request and provide feedback Move passengers betweenfloors Process Conversion level, Of Fire, Analouge Control elevator cars security etc. to information. digital etc. Enable effective maintenance And services Provide data entry /OP facilities Accept passenger request Process and provide feedback Conversion of user input data OP data to ( convert to Generate Control useful signals machine commands format) Enable effective maintenance And services

19. Provide data entry /OP facilities Accept passenger request and provide feedback Process user input data ( convert to machine format) Conversion of OP data to useful signals Generate Control commands Provide fault tolrance and maintenance functions Receive input data Generate Control commands Process data ( convert to machine format) Transmit control commands Use control algorithm Provide fault tolrance and maintenance functions

20. Provide data entry /OP facilities Receive input data Receive input data Accept passenger request and provide feedback Generate Control Generate Control Process user input data ( convert to machine format) commands commands Process Process Conversion of OP data to useful signals Transmit Transmit data data Use control Use control control control Generate Control commands ( convert ( convert algorithm algorithm commands commands to to machine machine Provide fault tolrance and maintenance functions format) format) Provide fault Provide fault tolrance tolrance and and maintenance maintenance functions functions

21. Functional hierarchy Move Passengers between floors More level 1 Functions Accept passenger requests, provide feedback Control elevator cars Func. 2.1 Func. 2.1 Provide i/o interface Process data Provide control commands Func. 1.1.1 Func. 1.1.1 Func. 1.1.1 Func. 1.1.1 Func. 1.1.1 Func. 1.1.1 Lower level Functions

23. EXAMPLE: Functional Decomposition using HP templateSystem: Institute service kiosk

24. Accept customer input through terminal Provide information Convert input data for processing Process data and generate results Provide data output , Self Test and and Redundancy Redundancy Management Management Processing Processing

26. Functional hierarchy Provide information service More level 1 Functions Accept customer requirements/inputs Provide customer services Navigat-ional info Acade-mic info Provide i/o interface Process data Provide control commands Func. 1.1.1 Func. 1.1.1 Func. 1.1.1 Func. 1.1.1 Func. 1.1.1 Func. 1.1.1 Lower level Functions

27. FUNCTIONAL DECOMPOSITION USING IDEF0 TEMPLATE