Session 3. Session Speaker : Dr. Govind R. Kadambi

Transcription

1 Session 3 Complex Systems and System Development Process Session Speaker : Dr. Govind R. Kadambi M S Ramaiah School of Advanced Studies 1

2 Session Objectives To understand : Structure, Hierarchy and Model of complex system Definition of System level and functional blocks System Boundary, Environment and interactions Management of interactions and interfaces System development process and life cycle System Engineering Process Model M S Ramaiah School of Advanced Studies 2

3 Session Topics Definition of Complex System System Building Blocks System Interfaces and Interactions System Boundary and Environment Management of Interfaces and Interactions Hierarchy of Complex System Physical and Functional blocks System Life Cycle System Engineering through System Life Cycle Characteristics of System Development Process System Engineering Process Model Testing throughout System Development M S Ramaiah School of Advanced Studies 3

4 Structure of Complex Systems System Engineer raises the question of how deep that understanding of a broad knowledge needs to be in the development of a complex system System Engineer is not an equivalent Specialist in all traditional engineering disciplines System Engineer must recognize such factors as program risks, technological performance limits, and interfacing requirements, and make trade-off analyses among design alternatives Possible to provide an important insight through structural hierarchy of modern systems System building blocks that make up the large majority of systems and represent the lower working level of technical understanding for systems Engineers M S Ramaiah School of Advanced Studies 4

5 Structure of Complex Systems Technical trade offs affecting system capabilities must be worked out Interface conflicts must be resolved to realize a balanced design across the entire system Nature of these building blocks in the context of they being fundamental elements and the related interfaces and interactions is equally important in the development of complex system M S Ramaiah School of Advanced Studies 5

6 Hierarchy of Complex Systems Why understanding of Hierarchy? - To define the scope of systems engineering - To determine what the System Engineer needs to know - To define the general scope and structure of a system Definition of system is inherently applicable to different levels of aggregation of complex interacting elements Every system is a subsystem of a higher-level system Every sub system can be considered as a system Super systems as overreaching systems Concept of system of systems M S Ramaiah School of Advanced Studies 6

7 Model of a Complex System Ambiguity of the scope of system leads to confusion Useful to create a more specific model of a typical system Technique of modeling is a basic tool of systems engineering Technique is useful to construct a typical complex system model in terms of its constituent parts Model is supposed to define a relatively simple and readily understood system architecture Complex systems have a hierarchical structure consisting of subsystems Subsystems are major interacting elements Subsystems themselves are composed of more sinple functional entities usually called parts M S Ramaiah School of Advanced Studies 7

8 Definition of System Level Majority of systems are developed by an integrated acquisition process System Subsystems Components Subcomponents Parts Systems: - Possess the properties of engineered system - Perform a significant useful service with only the aid of human operators and standard infrastructure Subsystem: - First subordinate level in system hierarchy - Major portion of system performing closely related subset of overall system functions - Cannot perform without the companion subsystem M S Ramaiah School of Advanced Studies 8

9 Model of Complex Systems Component- - Commonly used to refer lower level entities - Sometimes can be referred to middle of system level Subcomponents: - Level below the component building blocks - Perform elementary functions and are composed of parts Parts: - Lowest level entity - Perform no significant function except in combination with other parts - Standard sizes and types as well as commercial availability M S Ramaiah School of Advanced Studies 9

10 System Design Hierarchy Model of Complex System : System, Subsystem, Component, Parts M S Ramaiah School of Advanced Studies 10

11 System Engineer vs. Design Specialist Intermediate system component occupies a central position in system development process Component specification along with compatible interface is an important task of systems engineers System and Design engineers co ordinate, communicate, identify and discuss technical problems as well as related solutions System Engineer s Domain: Extends down through the component level Is as detailed as a system engineer usually needs to go Extends across several system categories Design Specialist s Domain Extends from the part level up through the component level Overlaps the domain of the systems engineers Is usually limited to a single technology/discipline M S Ramaiah School of Advanced Studies 11

12 System Engineer vs. Design Specialist Knowledge domain of Systems Engineer and Design Specialist M S Ramaiah School of Advanced Studies 12

13 Functional building Blocks Three basic entities that constitute the media on which systems operate are : Information:Content of all knowledge and information Material : Substance of all physical objects Energy : Energizes the operation and movement of all active system components Sub divisions of Information: Signal elements- Elements dealing with propagating information Data elements Elements dealing with stationary information Four functional elements: Signal Elements Data Elements Material Elements Energy Elements M S Ramaiah School of Advanced Studies 13

14 Functional Elements Basic building blocks of all engineered systems Characterized by functional and physical attributes Significant element, performing a distinct and significant function typically involving several elementary functions Singular element, should fall within the scope of a single engineering discipline Common element, function performed by each element can be found in a variety of system types Functional Building Block- elements: Functional equivalents of components, four classes by medium Signal element: sense and communicate information Data element: interpret, organize, and manipulate information Material element: provide structure and process materials Energy element: provide energy and power M S Ramaiah School of Advanced Studies 14

15 System Functional Elements Functional Element: Signal, Data, Material, Energy M S Ramaiah School of Advanced Studies 15

16 Physical Building Blocks: Components Physical Building Block: Physical embodiment of the functional elements Hardware and software Same distinguishing characteristics of significance, singularity and commonality Component Design Elements : Electronics Electro-Optical Electro-Mechanical Mechanical Thermomechanical Software M S Ramaiah School of Advanced Studies 16

17 Physical Building Block Physical Elements: Electronics, EO, EM, Mechanics, TM, Software M S Ramaiah School of Advanced Studies 17

18 Application of System Building Block System building block model will be useful in several ways Identifying actions capable of achieving operational outcomes (signal, data, material and energy) Identifying the classes of functions need to be performed by the system will help the group the appropriate functional elements into subsystems Facilitating functional partitioning and definition Identifying subsystem and component interfaces Visualizing the physical architecture of the system Suggesting types of component implementation technology Helping software engineers acquire hardware domain knowledge M S Ramaiah School of Advanced Studies 18

19 System Environment System Environment may broadly be defined as anything that is outside of the system that interacts with the system Interaction of the system with the environment form a core activity of the systems engineering Important to identify and specify all the ways in which the system and the environment interact at the outset of system development Understanding of the physical basis of interaction to ensure the system requirements fully reflect the operating conditions Outside the system: System operators, Maintenance, Housing, and Support Systems Shipping, Storage, and Handling Weather and other physical environments M S Ramaiah School of Advanced Studies 19

20 System Boundary To identify the environment in which the system has to operate Implies that what is inside the system and what is outside to be specified System definition contradicts the traditional system Human Operator is an integral part of the system from conventional definition For system engineers, human operator is an element of system environment and impose interface requirements to be met. Accordingly, according to systems engineering, operator is external to the system Systems Engineers also get involved in interface decisions M S Ramaiah School of Advanced Studies 20

21 Types of Environment Interactions Primary and secondary interactions Primary Interaction - elements interact with the primary functions of the system (functional inputs, outputs, controls) Secondary Interactions- system interaction with elements in an indirect manner (Physical support, ambient temperature) Functional interaction of a system with the environment include the inputs, outputs and human control interfaces Operational maintenance is quasi- functional interface Physical environment includes support systems, systems housing, handling, and storage M S Ramaiah School of Advanced Studies 21

22 Input and Output: Environmental Interactions -Systems operate on external stimuli and or material in a manner to process the inputs in a useful way System Operators: -Operator is a part of system environment -Human- Machine interface is critical -Most complex to define and test Operational Maintenance: -Required for system readiness and operational reliability -System be designed to provide access for monitoring, testing and repair -Requirements not obvious at the outset, nevetheless must be addressed early in the development process M S Ramaiah School of Advanced Studies 22

23 Environmental Interactions Support Systems: are that part of infrastructure on which the system depends for carrying out its mission Necessary to provide interfaces that are compatible with and capable of utilizing the support facilities System Housing : Stationary systems are installed in an operating site Itself imposes compatibility constraints System housing can also provide protection from variations in temperature, humidity and other external factors Shipping and Handling Environment: Requirement of transporting imposing special conditions for which design may be required Extreme temperatures, humidity, shock, and vibrations are important factors for design considerations M S Ramaiah School of Advanced Studies 23

24 System Environment- Example -System operators, Maintenance, Housing, and Support Systems -Shipping, Storage, and Handling, Weather and physical environments M S Ramaiah School of Advanced Studies 24

25 System Interface and Interactions System Interface is a critical Systems Engineering Interface is a boundary along which the system interacts with the environment Definition and control of interface is a particular responsibility of Systems Engineer Interface requires the knowledge both the system and the environment Effect interactions between components Require identification, specification, coordination, and control Require that test interfaces be provided for integration and maintenance Include elements that connect, isolate, or convert interactions M S Ramaiah School of Advanced Studies 25

26 Management of Interface Identification and description of interfaces as a part of system concept definition Coordination and control of interfaces to main system integrity during engineering development, production and system enhancements System s Internal Interface : Boundary between individual components of the system Boundary between System Engineer and Individual component specialist Definition and implementation includes design trade-offs that impact both the components M S Ramaiah School of Advanced Studies 26

27 Interactions Interactions between individual system concept are effected through the connecting interface Functional interactions are effected by physical interactions External system interaction also occurs during maintenance Requires access to vital system functions of the system Calls for Special test points Provision of Built In Test (BIT) System Engineering has to address all these concerns and provisions M S Ramaiah School of Advanced Studies 27

28 System Interface - Example Functional Interface and Physical Interfaces M S Ramaiah School of Advanced Studies 28

29 System Development Process M S Ramaiah School of Advanced Studies 29

30 Characteristics of System Development System Development Process: Evolution of a particular system from the time a need was realized and a feasible technical approach is identified, through its developmental phase culminating into operation Typical characters of major system development: Complex Effort Meets Important user needs Varying time duration Many interrelated tasks Interdisciplinary Several Organization Specific Schedule and Budget M S Ramaiah School of Advanced Studies 30

31 System Life Cycle (SLC)- Introduction SLC is a step by step evolution of a new system from concept through development, and onto production as well as operation Role of Systems engineers keeps changing in each of these steps Essential to have concise and clarity in relating Systems Engineering functions to their roles in specific phase of life Life cycle models subdivide the system life into steps that separate major decision milestones Derivation of a life cycle model has to meet two primary objectives Steps in life cycle have correspond to the progressive transitions in the principal Systems Engineering M S Ramaiah School of Advanced Studies 31

32 Systems Engineering Life Cycle- Model Defined steps have to be mapped into the principal life cycle models in use by Systems Engineering Community Derived model is referred as Systems Engineering Life Cycle Three models: Department of Defense Model (DoD 5000) International Model ISO/IEC National Society of Professional Engineers Model DoD Model: US department of Defense Concept and technology Development System Development and Demonstration Production and Development Operation and Support Need Acquisition is considered as a part but not included M S Ramaiah School of Advanced Studies 32

33 SLC Models International ISO/IEC Model : International Standard Organization (ISO) International Electrotechnical Commission Issued it in 2001 Institutionalized for US industries Six Stages: Concept Development Production Utilization Support Retirement M S Ramaiah School of Advanced Studies 33

34 Professional Engineering Model National Society of Professional Engineers (NSPE) Model tailored to the development of commercial systems Technology Driven Model More suited for new product to be developed through technological advances NSPE is an alternative view to DoD model Six stages Conceptual Technical Feasibility Development Product Preparation Full Scale Production Product Support M S Ramaiah School of Advanced Studies 34

35 System Life Cycle System Life Cycle Development Production Operation Disposal Development of a systems engineering life cycle model Life cycle models subdivide the system life into half dozen or so steps that separate major decision milestones. System Development Life Cycle Model: Department of Defense Model (DoD 5000) International Model ISO/IEC National Society of Professional Engineers Model M S Ramaiah School of Advanced Studies 35

36 System Development Process System Development Characteristics: Complex Efforts, Important User s need Development Duration, Many Interrelated Tasks Involve different discipline, perform by several organizations Specific schedule and budget System Development Life Cycle Model: Department of Defense Model (DoD 5000) International Model ISO/IEC National Society of Professional Engineers Model System Engineering Model: 3 stages, 6 phases: Concept, Engineering, Post development M S Ramaiah School of Advanced Studies 36

37 System Life Cycle Stages Concept Development Stage Establish the system need Explore feasible concepts Select preferred system concept Engineering Development Stage Validate new technology Transform concept into hardware and software designs Build and test production model Post Development Stage Produce and deploy the system Supports system operation and maintenance Each stage may be further divided two or three phases Life cycle of software-intensive systems M S Ramaiah School of Advanced Studies 37

38 Comparison of System Life Cycle Model M S Ramaiah School of Advanced Studies 38

39 Product and System Life Cycle M S Ramaiah School of Advanced Studies 39

40 System Engineering Process Models-1 M S Ramaiah School of Advanced Studies 40

41 System Engineering Process Models-II M S Ramaiah School of Advanced Studies 41

42 VEE Process Model M S Ramaiah School of Advanced Studies 42

43 Identification of System Design Consideration M S Ramaiah School of Advanced Studies 43

44 Application Areas for System Engineering M S Ramaiah School of Advanced Studies 44

45 Life-Cycle Commitment System-Specific Knowledge and Cost M S Ramaiah School of Advanced Studies 45

46 System Engineering and Engineering Discipline Influence on Design M S Ramaiah School of Advanced Studies 46

47 Principal Stages in System Life Cycle M S Ramaiah School of Advanced Studies 47

48 Concept Development Stage 3 Phases Needs Analysis Phase - Define and validate the need for a new system Demonstrate its feasibility and defines system operational requirement Concept Exploration Phase - Explore feasible concepts Define functional performance requirements Concept Definition Phase - Examine alternative concepts Select preferred concept on basis of performance, cost, schedule, and risk Define system functional (A) specifications M S Ramaiah School of Advanced Studies 48

49 Concept Development Stage - Diagram M S Ramaiah School of Advanced Studies 49

50 Engineering Development Stage 3 Phases Advanced Development Phase - Identify areas of risk Reduce risks through analysis, development, and test Define system development (B) specification Engineering Design Phase - Perform preliminary and final design Build and test hardware and software components (ICs) Integration and Evaluation Phase Integrate components into production prototype Evaluate prototype system and rectifies deviations M S Ramaiah School of Advanced Studies 50

51 Engineering Dev. Stage - Diagram M S Ramaiah School of Advanced Studies 51

52 Post Development Stage And Phases Production Phase - Develop tooling and manufactures system product Provide system to user and facilities initial operations Operation and Support Phases - Support system operation and maintenance Develop and support in-service updates Integration and Evaluation Integrate components into production prototype Evaluate prototype system and rectifies deviations M S Ramaiah School of Advanced Studies 52

53 Evolution of System Life Cycle M S Ramaiah School of Advanced Studies 53

54 Principal Participants in System Eng. M S Ramaiah School of Advanced Studies 54

55 Evolution of System Representation M S Ramaiah School of Advanced Studies 55

56 System Engineering Method Requirement Analysis - Identify why requirements are needed Functional definition - Translate requirements into functions Physical Definition - Synthesize alternative physical implementation Design Validation - Models the system environment M S Ramaiah School of Advanced Studies 56

57 System Engineering Top-Level Flow Four basic activities: Requirements analysis (Problem Definition) Functional definition (Functional Analysis and Allocation) Physical definition (Synthesis of Physical Analysis and Allocation) Design validation (Verification, Evaluation) M S Ramaiah School of Advanced Studies 57

58 System Engineering Method Flow M S Ramaiah School of Advanced Studies 58

59 Requirements Analysis (1) Organization and interpretation The system model, which identifies and describes all design choices made and validated in the preceding phases. Requirements (or specifications) that define the design, performance, and interface compatibility features of the system or system elements to be developed during the next phase. Specific progress to be achieved by each component of the engineering organization during the next phase Clarification, Correction, and Quantification Stated requirements are often incomplete, inconsistent, and vague To be varied with the nature of the system, its degree of departure from predecessor systems, the type of acquisition process employed, and the phase itself M S Ramaiah School of Advanced Studies 59

60 Functional Definition (2) Translation into Functions: Selecting, subdividing, or aggregating functional elements Identification and description of all functions to be provided To be reflected in system functional specifications Trade-off Analysis: Inductive process in which a set of postulated alternatives are examined and the one judged to be best for the intended purpose is selected Trade-offs involve: the comparison of alternatives with those that are superior in others To be necessary to explore a sufficient number of alternative implementations Functional Interactions: Early identification of all significant functional interactions modular Identification of all external interactions and the interfaces M S Ramaiah School of Advanced Studies 60

61 Physical Definition (3) Synthesis of Alternative System Elements Decisions regarding the specific physical form: include choice of implementation media, element form, arrangement, and interface design are made by the use of trade-off analysis Selection of Preferred Approach To be necessary to define a set of evaluation criteria and establish their relative priority 1. All viable alternatives are considered, 2. A set of evaluation criteria is established, and 3. The criteria are prioritized and quantified where practicable Interface Definition Definition and control of inter face both internal and external Adjustment to the parent elements will be required M S Ramaiah School of Advanced Studies 61

62 Design Validation (4a) Modeling the System Environment In the concept development stage: the model is largely functional In later stags of development: various aspects of the environment may be reproduced Effort required to model the environment of a system to be considered at the same level of priority as the design of the system itself May even require a separate design effort comparable to the associated system design activity Tests and Test Data Analysis: 1. All critical system characteristics need to be stressed beyond their specified limits to uncover incipient weak spots 2. All key elements need to be instrumented to permit location of the exact sources of deviations in behavior M S Ramaiah School of Advanced Studies 62

63 Design Validation (4b) Tests and Test Data Analysis (continued ) 3. A test plan and an associated test data analysis plan must be prepared to assure that the requisite data are properly collected and are then analyzed as necessary to assure a realistic assessment system compliance. 4. All limitations in the tests due to unavoidable artificialities need to be explicitly recognized, and their effect on the results compensated or corrected for, as far as possible. 5. A formal test report must be prepared to document the degree of compliance by the system and the source of any deficiencies. Preparation for the Next Phase Each phase produces a further level of requirement or specification to serve as a basis for the next phase Documentation of the design decisions made in course of the current phase Establishment of the goals for the succeeding phase M S Ramaiah School of Advanced Studies 63

64 System Engineering Method in Life Cycle M S Ramaiah School of Advanced Studies 64

65 System Eng. Spiral Life Cycle Model An iterative application of the system engineering method Continuing review and updating of work performed Conclusion reached in the prior phase of the effort M S Ramaiah School of Advanced Studies 65

66 System Eng. Spiral Life Cycle Model M S Ramaiah School of Advanced Studies 66

67 Testing throughout System Development Unknowns Known unknowns : to be evident at the beginning of the project can be resolved easily Unknown unknowns : to be only identified later could be serious problem Transforming the Unknown into the Known Experience gathered during previous system developments and supported by a high degree of technical insight and a what if attitude Unwise to wait until the design is fully implemented before determining whether or not the approach is sound. System-level rather than a component-level decision M S Ramaiah School of Advanced Studies 67

68 Is it O.K? System Test and Evaluation Design Engineer and Test Engineer A process to identify unknown design defects - Verifies resolution of known unknowns Uncover Unknown unknowns (unks-unks) and their causes Late resolution of unknowns may be extremely costly Test planning and analysis is a prime systems engineering responsibility Most intensive use of testing is the last phase of system development, integration and evaluation M S Ramaiah School of Advanced Studies 68

69 Session Summary Complex systems can be represented by a hierarchical structure comprising parts, subcomponents, and subsystems Domain of a System Engineer extends down through the component level Domain of a design specialist extends from the part level up through the component level System Building blocks are at the levels of component System building blocks are basic blocks of all engineered system Functional elements are functional equivalents of components Four basic types of functional elements are signal, data, material and energy M S Ramaiah School of Advanced Studies 69

70 Session Summary Components are physical embodiments of functional elements System building block models are useful for identifying actions, facilitating functional partition and identfying interfaces System environment includes everything outside the system that can interact with it Interfaces are a critical concern of Systems Engineering Interfaces effect interactions between components and include elements that can connect, isolate or convert interactions M S Ramaiah School of Advanced Studies 70

71 Session Summary Major system development program is an extended complex effort to satisfy an user need System Life Cycle has three major stages namely concept development, engineering development and post development stage Concept development deals with system need, feasible concept and selection of preferred system concept Engineering development validates new technology, transforms concept into hardware and software designs as well as build and test of prototype model Post Development produces and deploys the system, supports operation and maintenance of systems Concept development stage has three phases namely need analysis, concept exploration and concept definition M S Ramaiah School of Advanced Studies 71

72 Session Summary Engineering development has three phases: Advanced development, Engineering design and Integration and Evaluation Post Development stage is divided in to two phases: Production, Operation and Support New system progressively materializes during its development Key participants in system development change during development are: System Engineering, System representatives as well as documents System Engineering method involves four basic steps: Requirement Analysis, Functional Definition, Physical Definition and Design validation M S Ramaiah School of Advanced Studies 72