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Agenda for design activity

Agenda for design activity. 1. Tracing requirements 2. Managing requirements 3. Requirements management tools 4. Homework. 1. Tracing requirements. Types of tracing Complexity of tracing Reasons for tracing Observations Suggestions. 1. Tracing requirements. Design. Design. Design.

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Agenda for design activity

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  1. Agenda for design activity • 1. Tracing requirements • 2. Managing requirements • 3. Requirements management tools • 4. Homework

  2. 1. Tracing requirements • Types of tracing • Complexity of tracing • Reasons for tracing • Observations • Suggestions 1. Tracing requirements

  3. Design Design Design Design Design Types of tracing (1 of 2) Req Req Req Req Req Req Req Req Req Req Creation End Straight through Expansion Focus Five types of tracing 1. Tracing requirements

  4. Design Design Design Design Design Types of tracing (2 of 2) No hazardous material Calculation Graphing Missile No hazardous material Spreadsheet Instrumentation Straight through Focus Creation Weight Bedroom on east side Weight A Weight B Building supplies Expansion End An example of each type

  5. Complexity of tracing (1 of 2) • Often used in tracing and tracing Spec Spec Spec Simple tracing flows from spec to spec and doesn’t include tracing to design. It’s the more common practice 1. Tracing requirements

  6. Complexity of tracing (2 of 2) Spec contract Design of the higher product Stakeholders • More complex but provides truer tracing picture Design contract Spec I/F Spec contract Stakeholders Stakeholders Design Design Note: Flow within a rectangle or ellipse not shown Flow through design is more complex and is a less common practice. However, it produces less problems 1. Tracing requirements

  7. Reasons for tracing (1 of 5) • Reason 1: tracing -- Where did requirement get implemented? • Less precise linkage criteria than tracing for verification/validation • Often done by doing tracing first 1. Tracing requirements

  8. Reasons for tracing (2 of 5) • Reason 2: tracing for verification/validation -- What lower requirements are used in verifying/validating higher requirements? • Simplest and most repeatable 1. Tracing requirements

  9. Reasons for tracing (3 of 5) • Reason 3: tracing for origin -- Where did each requirement come from; why does it exist? • more linkages to explain how design creates requirements 1. Tracing requirements

  10. Reasons for tracing (4 of 5) • Reason 4: tracing for change impact -- If one requirement changes, what other requirements must change? • More linkages to reflect impacts of requirements on each other 1. Tracing requirements

  11. Reasons for tracing (5 of 5) • The four different reasons for tracing can result in four different sets of linkages 1. Tracing requirements

  12. Observations (1 of 4) • Tracing is a best practice • Supports verification and validation • Makes sure requirements are implemented • Prevents unnecessary requirements • Shows how changing one requirement changes others • Meets customer expectation 1. Tracing requirements

  13. Observations (2 of 4) • Tracing is expensive • Tracing is complex and expensive; $benefit/$cost > 1? • Many believe cost far out weighs the benefit; takes time, diverts resources, degrades engineers, and drives tools • Lack of training & rules make trace not repeatable or dependable 1. Tracing requirements

  14. Observations (3 of 4) • The following rules-of-thumb can cause trouble • All requirements must come from somewhere • All requirements must go somewhere • All requirements shall trace in one direction • Tracing shall be from spec to spec and not within a spec • Tracing shall not be from spec to design • There shall be one “shall” per requirement • All requirements shall be individually traced 1. Tracing requirements

  15. Observations (4 of 4) • Design is an essential part of flowdown and trace • Design is difficult to capture in requirements management tools • Few people use trace to understand the effect of a requirement change on other requirements 1. Tracing requirements

  16. Suggestion (1 of 3) • Set customer expectations • Negotiate with customer to minimize effort for design and verification • Document agreements -- in the spec if possible using clarifications, definitions, and examples 1. Tracing requirements

  17. Suggestion (2 of 3) • Choose a type of tracing such as tracing to confirm verification and validation • Provide rules and training • Provide for independent confirmation of tracing 1. Tracing requirements

  18. Design Design Suggestion (3 of 3) Req Req Req Expansion Focus Req Req Req Req Req Req Expansion Focus Req Req Req Flow expansion and focus through design -- not directly 1. Tracing requirements

  19. 2. Managing requirements • Requirements attributes • Data interface attributes • Physical interface attributes • Documenting requirements • Managing requirements change 2. Managing requirements

  20. Requirements attributes (1 of 2) • Requirement -- text • Title -- short text • Numerical identifier -- added by management tool • Product unique identifier (PUI) -- added by engineers • Verification method -- how requirement verified 2. Managing requirements

  21. Requirements attributes (2 of 2) • Owner -- person responsible for success • Stakeholders -- people with an interest • Change history -- change dates • Flowdown/traces -- flowdown and trace links • Rationale -- why requirement is the way it is 2. Managing requirements

  22. Data interface attributes • Data item • Criteria • Timing • Units and enumeration • Format • Ranges • Accuracy 2. Managing requirements

  23. Physical interface attributes (1 of 2) • Electrical • Signals • Power • EMI/EMC • Grounding 2. Managing requirements

  24. Physical interface attributes (2 of 2) • Mechanical • Dimensions • Mounting • Alignment • Weight • Heating • Cooling 2. Managing requirements

  25. Documenting requirements • Media • Paper • Office computer tools • Data base • Format • Contractor chosen • Commercial standard • MIL-STD-490A • MIL-STD-490B 2. Managing requirements

  26. Managing requirements change • Often handled through configuration management • Techniques • Data base • Change pages • Red-line changes 2. Managing requirements

  27. 3. Requirements management tools • INCOSE tools survey • INCOSE tool-selection criteria • Tools surveyed by INCOSE • Selection considerations for ease of use • Selection considerations for compatibility • Selection criteria for satisfaction 3. Requirements management tools

  28. INCOSE tools survey • Comparison made by National Council on Systems Engineering (INCOSE) • Internet address: http\\www.incose.org/workgrps/tools/req_surv.htm 3. Requirements management tools

  29. INCOSE tool-selection criteria (1 of 2) • 1. Capturing requirements identification • 2. Capturing system element structure • 3. Requirements flowdown • 4. Traceability analysis • 5. Configuration management • 6. Documents and other output media 3. Requirements management tools

  30. INCOSE tool-selection criteria (2 of 2) • 7. Groupware • 8. Interfaces to other tools • 9. System environment • 10. User interfaces • 11. Standards • 12. Support and maintenance • 13. Other features 3. Requirements management tools

  31. Tools surveyed by INCOSE (1 of 2) • Cadence -- Bones • Boeing North American, Inc. -- CASETS • Vitech -- CORE • Mesa Systems Guild -- Cradle/SEE • Zycad -- DOORS • Teknowledge -- ProductTrack • Image That -- Extend • Ascent Logic -- RDD-100 • Integrated Chipware Inc. -- RTM • TD Technologies -- SLATE 3. Requirements management tools

  32. Tools surveyed by INCOSE (2 of 2) • Cadence -- SPW • Compliance Automation -- VITAL LINK • Teledyne Brown Engineering -- XTie-RT • Nu Thena Systems -- Foresight • MathWorks -- MATLAB, Simulink, Stateflow, Real-Time Workshop • Rational (Requisite) -- RequisitePro V2.0 • Statemate -- Magnum 3. Requirements management tools

  33. Considerations for ease of use • Using • Learning • Putting information into the tool • Extracting information from the tool • Knowing what information is in the tool • Navigating among information • Grouping information for comparison and reports • Assuring quality such as spell checking 3. Requirements management tools

  34. Considerations for compatibility • Computer and operating system being used on the project • Way team members work 3. Requirements management tools

  35. Considerations for satisfaction • Gain understanding of the tool before committing to use tool • Avoid choices based on demo by sales person 3. Requirements management tools

  36. 4. Homework • Diagram • Customer wants • Timepiece spec • Timepiece contract • Design • Clock spec • AC adapter spec • Problem 4. Homework

  37. Diagram Customer wants C1, C2, C3 Timepiece spec S1 Timepiece contract X1 Timepiece design D1, D2, D3, D4, D5 Clock spec T1 Adapter spec U1, U2 4. Homework

  38. Customer wants • C1: I want a timepiece that I can look at and determine time accurate to one minute per day since the last setting • C2: Cost, size, weight, mechanism, style, power, and everything else are of no consequence • C3: I will give a flat $100 for the timepiece regardless of design 4. Homework

  39. Timepiece spec • S1: The timepiece shall display time accurate to one minute per day since the last setting 4. Homework

  40. Timepiece contract • X1: Customer will pay $100 for timepiece meeting timepiece spec 4. Homework

  41. Design (1 of 2) • D1: I’ll design the timepiece using existing components. • D2: I want to make a lot of profit • D3: The Dilmore catalogue shows that its least expensive clock is the model 100 for $4. It is resettable to correct the time, is accurate to one minute per day since the last setting, but requires an AC adapter 4. Homework

  42. Design (2 of 2) • D4: The Hazel catalog shows the model 200 as its least expensive AC adapter compatible with the Dilmore model 100 clock, and the adapter costs $1. • D5: The model 200 AC adapter comes in either black or beige at no extra cost. In my opinion, beige is more attractive in the customer’s environment 4. Homework

  43. Clock spec • T1: Clock shall be a Dilmore model 100 clock 4. Homework

  44. AC adapter spec • U1: AC adapter shall be a Hazel model 200 AC adapter • U2: AC adapter shall be beige 4. Homework

  45. Problem (1 of 4) • 1. What items need to be successfully implemented to verify item D5? -- a. T1, U1, & U2; b. U1 & U2; c. U1; d. U2 • 2. For tracing purposes, what items implement item X1? -- a. D3; b. D4, c. D3 & D4; d. D3, D4, & D5 4. Homework

  46. Problem (2 of 4) • 3. For tracing purposes, where did the requirements for item D4 come from? -- a. D3; b. D1, D2, & D3; c. D1, D2, D3, & X1; d. S1, D1, D2, & D3 • 4. For tracing purposes, what items implement item C2? -- a. none of the listed items, b. S1 & X1, c. D1, D2, & D3; d. T1, U1, & U2 4. Homework

  47. Problem (3 of 4) • 5. What items need to be successfully implemented to verify item S1? -- a. C1; b. D3; c. D2 & D3; d. D3, D4, & D5 • 6. For tracing purposes, where does item D1 come from? -- a. none of the listed items; b. S1; c. X1; d. S1 & X1 4. Homework

  48. Problem (4 of 4) • 7. For tracing purposes, where does item U2 come from? -- a. none of the listed items; b. D5; c. D4; d. S1 • 8. If item D3 were to change to no longer require an AC adapter, which items would change? -- a. no items would change; b. D4; c. D4 & U1; d. D4, D5, U1, & U2 4. Homework

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