1. 7. Design1 Agenda for design activity r1. Flow diagrams r2. Instrumentation r3. State tables r4. Decision tables r5. Homework

2. 7. Design2 1. Flow diagrams rDefinition rAutomated techniques rFlowing down interfaces 1. Flow diagrams

3. 7. Design3 Definition (1 of 2) rFlow diagrams show the flow of physical quantities, data, and control into, out of, and through a product. Examples are Power Cooling air Signals Control 1. Flow diagrams

4. 7. Design4 Definition (1 of 2) rDiagrams can be functional or physical rControlling the flow is one of the strongest influences a product engineer has on the development of a product 1. Flow diagrams

5. 7. Design5 Automated techniques rExcel spreadsheet rData bases; e.g. TeamWork 1. Flow diagrams

6. 7. Design6 Flowing down interfaces Product requirements Lower product A requirements Lower product B requirements Interface Product design concept; e.g.,power control Product requirements suggest a concept. Design develops this concept and creates requirements for lower products and I/Fs. The I/F requirements become lower requirements Product requirements suggest a concept. Design develops this concept and creates requirements for lower products and I/Fs. The I/F requirements become lower requirements requirements 1. Flow diagrams

7. 7. Design7 2. Instrumentation rNeed for instrumentation rExamples of instrumentation rValue of embedding instrumentation rCosts of instrumentation 2. Instrumentation

8. 7. Design8 Need for instrumentation rBuild and verify activities benefit from instrumentation rCustomers are wary about depending upon the results of simulation rCustomers feel more comfortable with measured data 2. Instrumentation

9. 7. Design9 Examples of instrumentation rTime tagging rThroughput rTrouble shooting rAccess to unavailable features 2. Instrumentation

10. 7. Design10 Value of embedding instrumentation rLess expensive than adding later rCommon to leave in the system 2. Instrumentation

11. 7. Design11 Costs of instrumentation rExpensive to collect all variables produced by the system and then figure out what to do with the data later rExpensive without stated objective rData reduction expensive 2. Instrumentation

12. 7. Design12 3. State diagrams r Example 1 r Logical control requirements in words r Complete state diagram r Simplified state diagram r Number of paths in state diagram r Truth table 3. State diagrams

13. 7. Design13 Example 1 Remote terminal (RT) 1 Master power bus communications self test loading operation closedopen RT 1 power switch Goal -- turn on power. Establish communications, load, and operate Goal -- turn on power. Establish communications, load, and operate 3. State dagrams

14. 7. Design14 Logical control requirements in words rTwo power control states 1. Off 2. On rOff when power switch is open. rOn when power switch is closed 3. State dagrams

15. 7. Design15 Complete state diagram 1 off 2 on RT 1 power switch open RT 1 power switch closed RT 1 power switch open RT 1 power switch closed Power-state state diagram showing state transition paths and same-state transition paths Power-state state diagram showing state transition paths and same-state transition paths Power-state state diagram transition paths same- state transition paths 3. State diagrams

16. 7. Design16 Simplified state diagram 1 off 2 on Power switch open Power switch closed Power-state state diagram showing only state transition paths and not showing the same-state transition paths. This form is used often. Power-state state diagram showing only state transition paths and not showing the same-state transition paths. This form is used often. Power-state state diagram 3. State diagrams

17. 7. Design17 Number of paths in a state diagram rMaximum number of state transition paths is n 2 rMaximum number of same-state transition paths is n rMaximum number of state transition paths excluding the same-state transition paths is n 2 - n. rMaximum number doesn’t need to be present 3. State diagrams

18. 7. Design18 Truth table RT 1 power switch RT 1 power state open off closed on decisions criterion A truth table has the same information as a state diagram, but it is less graphic A truth table has the same information as a state diagram, but it is less graphic 3. State diagrams

19. 7. Design19 4. Decision tables (1 of 2) r Using decision tables r Defining number of decisions r Defining the number of paths r Defining the number of options per path r Example 1 r Creating a decision table r Defining number of decision tables 4. Decision tables

20. 7. Design20 Decision tables (2 of 2) r Using canonical format r Ordering criteria rows r Adding results rows r Ordering decision columns r Checking correctness r Example 2 r Example 3 4. Decision tables

21. 7. Design21 Using decision tables (1 of 3) A decision table is a truth table with the information rearranged to be more compact when typed RT 1 power-state decision table 4. Decision tables

22. 7. Design22 Using decision tables (2 of 3) rIdentifies all possibilities rUncovers hidden paths rPromotes consistency rProvides concise documentation rAllows numerical checks for quality 4. Decision tables

23. 7. Design23 Using decision tables (3 of 3) rDecision tables don’t guarantee that the decisions are right 4. Decision tables

24. 7. Design24 Defining number of decisions (1 of 2) rNumber of decisions equals the product of the number of choices for each criterion. rMust account for all the decisions rA “-” in a decision table means that the decision table doesn’t care what the value of a criterion is. 4. Decision tables

25. 7. Design25 Defining number of decisions (2 of 2) RT 1 power-state Number of decisions per criterion Number of decisions It’s not necessary to show the number of decisions, but showing the number of decisions helps check the quality of the table It’s not necessary to show the number of decisions, but showing the number of decisions helps check the quality of the table 4. Decision tables

26. 7. Design26 Defining the number of paths RT 1 power-state It’s not necessary to show the number of paths, but showing the number of paths helps check the quality of the state diagram. Add current state even though not needed in example Show the matrix of paths 4. Decision tables

27. 7. Design27 Defining the number of options 2 1 3 2 14 1 2 32 matrix of options for each path (cell) total = 54 Matrix of options shows the number of options for each path. Each cell position represents a path Matrix of options shows the number of options for each path. Each cell position represents a path 4. Decision tables

28. 7. Design28 Example 1 (1 of 3) rTwo communications states 1. Not established (not est) 2. Established (est) rNot established if power state is off or ability to communicate is false rEstablished if power state is on and ability to communicate is true 4. Decision tables

29. 7. Design29 Example 1 (2 of 3) communications not established communications established power state = off or ability to communicate = false power state = on and ability to communicate = true 4. Decision tables

30. 7. Design30 Example 1 (3 of 3) Communications state 4. Decision tables

31. 7. Design31 Creating a decision table r1. Use Excel r2. Use ‘- to enter a minus into a cell r3. Use calculating capabilities to check numbers r4. Use non-proportional fonts r5. Use single character criteria 4. Decision tables

32. 7. Design32 Defining number of decision tables rUse one state diagram for each decision or concept rUse one decision table for each diagram rUse adjectives to avoid ambiguity 4. Decision tables

33. 7. Design33 Using canonical format Example canonical format 4. Decision tables

34. 7. Design34 Ordering criteria rows (1 of 3) rListed vertically rBased on the author’s guess at the impact of each criterion on state rStrongest criterion at the top rWeakest at the bottom 4. Decision tables

35. 7. Design35 Ordering criteria rows (2 of 3) rOrder of the rows can be changed rNumber of columns may change rNumber of decisions and the path matrix remain the same rConfirms accuracy of rearranging rows 4. Decision tables

36. 7. Design36 Ordering criteria rows (3 of 3) rChanging rows doesn’t leave table in canonical format rRow-order resulting in fewest number columns is not always obvious rObtained by trial and error 4. Decision tables

37. 7. Design37 Adding results rows Results in addition to state can be shown. However additional information may prevent merging some columns. Results in addition to state can be shown. However additional information may prevent merging some columns. 4. Decision tables

38. 7. Design38 Ordering decision columns (1 of 6) r1. Listed from left to right r2. Weakest criterion change fastest r3. Strongest change slowest 4. Decision tables

39. 7. Design39 Ordering decision columns (2 of 6) Example canonical format 4. Decision tables

40. 7. Design40 Ordering decision columns (3 of 6) r1. Find columns in which criteria have no effect r2. Merge such columns into a single column r3. Replace the values of the criteria that have no effect with a “-” 4. Decision tables

41. 7. Design41 Ordering decision columns (4 of 6) rThe columns must be mutually exclusive 4. Decision tables

42. 7. Design42 Ordering decision columns (5 of 6) Columns 1 and 2 in the left hand table are not mutually exclusive. Columns 1 and 3 in right hand table are not mutually exclusive. Results are conflicting. Columns 1 and 2 in the left hand table are not mutually exclusive. Columns 1 and 3 in right hand table are not mutually exclusive. Results are conflicting. Left handRight hand 4. Decision tables

43. 7. Design43 Ordering decision columns (6 of 6) rNot necessary to simplify rMinimizing makes printing the decision table easier and helps definition and implementation 4. Decision tables

44. 7. Design44 Checking correctness r1. Identify all states r2. Identify all criteria r3. Identify all values of each criterion r4. Enter the criteria values into the table in canonical format rGuidelines for Creating a DT (2 of 2) r5. Determine state corresponding to each column r6. Simplify the decision table r7. Confirm the number of decisions 4. Decision tables

45. 7. Design45 Example 2 (1 of 5) rThree load states 1. Not loaded or loading 2. Loading 3. Loaded rDetermined by Communications state (not est, est -- [F,T]) Load state (1, 2, 3 -- [1, 2,3]) Load command (none, stop, load -- [N, S, L]) Load status (none, failure, complete -- [N, F, C]) 4. Decision tables

46. 7. Design46 Example 2 (2 of 5) rIf (1) the comm state is not established or (2) the load status is failure, then the load state is not-loaded-or-loading rIf (1) the comm state is established and (2) the load status is not failure and (3) the load command is stop, then the load state is loading rIf (1) the comm state is established and (2) the load status is complete and (3) the load command is none and (4) the current load state is loading, then the load state is loaded 4. Decision tables

47. 7. Design47 Example 2 (3 of 5) not loaded or loading (1) comm state = not est or load status = failure comm state = est & load cmnd= load & load status = not failure comm state = est & load status =complete loading (2) loaded (3) comm state = not est or load status = failure comm state = est & load cmnd= load & load status = not failure 4. Decision tables

48. 7. Design48 Example 2 (4 of 5) 4. Decision tables

49. 7. Design49 Example 2 (5 of 5) Problems with developing decision table ad hoc 67>54 4. Decision tables

50. 7. Design50 Example 3 (1 of 4) rTwo operate states 1. Not operating 2. Operating rDetermined by Operate command (stop, operate -- [S,O]) Operate state (1, 2-- [1,2]) Load state (not loaded, loading, loaded [1,2,3] 4. Decision tables

51. 7. Design51 Example 3 (2 of 4) rIf (a) the operate command is stop, or (b) the operate command is operate and the loading state is 1 or 2, then the operate state is not operating rIf the operate command is operate, then the operate state is operating 4. Decision tables

52. 7. Design52 Example 3 (3 of 4) not operating (1) operating (2) operate command = operate operate command = stop 4. Decision tables

53. 7. Design53 Example 3 (4 of 4) 4. Decision tables

54. 7. Design54 5. Homework rProblem rSix states rDetermined by rOff state rNot communicating state rNot loaded state rLoading state rLoaded state rOperating state 5. Homework

55. 7. Design55 Problem r1. Create the decision table for this problem r2. Show the number of decisions for each column r3. Create the path matrix showing the number of paths between each state and the number of options for taking each path rHint -- Use Excel to generate the decision table in canonical format using the criteria in the order given, and don’t be intimidated by the words defining the resulting state 5. Homework

56. 7. Design56 Six States r1. Off r2. Not communicating r3. Not loaded r4. Loading r5. Loaded r6. Operating 5. Homework

57. 7. Design57 Determined by rPower command = on (false, true -- [F,T]) rCommunication status = OK (false, true -- [F,T]) rLoad status (failed, none, complete -- [F, N, C]) rLoad command (none, stop, load -- [N, S, L]) rState [1, 2, 3, 4, 5, 6] rOperate command (stop, operate [S, O] 5. Homework

58. 7. Design58 Off State rIf the power command is off, then the state is off 5. Homework

59. 7. Design59 Not Communicating State rIf (1) the power command is on and (2) the communication status is false, then the state is not communicating 5. Homework

60. 7. Design60 Not Loaded State rIf (1) the power command is on and (2) the communication status is true and (3) either (a) the load status is failed or (b) the load status is none and the load command is none and the state is 1-3, or (c) the load status is complete and the load command is none and the state is 1-3, or (d) the load status is none or complete and the load command is stop then the state is not loaded 5. Homework

61. 7. Design61 Loading State rIf (1) the power command is on and (2) the communication status is true and (3) either (a) the load status is none and the load command is none, and the state is loading or (b) the load status is none and the load command is load or (c) the load status is complete and the load command is load then the state is loading 5. Homework

62. 7. Design62 Loaded State rIf (1) the power command is on and (2) the communication status is true and (3) either (a) the load status is either none or complete, and the load command is none, and the current state is either loaded or operating, and the operate command is stop (b) the load status is complete, and the load command is none, and the current state is loading then the state shall be loaded 5. Homework

63. 7. Design63 Operate State rIf (1) the power command is on, and (2) the communication status is true and (3) the load status is none or complete, and (4) the load command is none, and (5) the current state is loaded or operating, and (6) the operate command is operate then the state shall be operating 5. Homework