4. Design/Control 1

Control and Data Agenda

1. Definitions 2. Decision tables 3. Data flow 4. Instrumentation 5. Homework

4. Design/Control 2

1. Definitions

Open-loop Vs closed-loop control Discrete Vs continuous control Logical Vs state-variable control States and status Mode Reconfiguration

There are several types of control.

1. Definitions

4. Design/Control 3

2. Decision Tables

Two goals in logical control Examples 1-4

2. Decision tables

4. Design/Control 4

Two Goals in Logical Control

Enumerating all control options Determining when the control applies

2. Decision tables

4. Design/Control 5

Example 1 -- Control of Remote Terminal

Remote terminal (RT)

1Master

power

buscommunications

self testloading

operation

closed open

RT 1 power switch

Goal -- turn on power, establish communications, load, and operate.

2. Decision tables

4. Design/Control 6

Logical Control Requirements in Words

Two power control states 1. Off 2. On

Off when power switch is open. On when power switch is closed

2. Decision tables

4. Design/Control 7

Complete State Diagram

1off

2on

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

transition paths

same- state transition paths

2. Decision tables

4. Design/Control 8

Simplified State Diagram

1off

2on

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

2. Decision tables

4. Design/Control 9

Number of Paths in a State Diagram

Maximum number of state transition paths is n2

Maximum number of same-state transition paths is n Maximum number of state transition paths excluding

the same-state transition paths is n2 - n. Maximum number doesn’t need to be present

2. Decision tables

4. Design/Control 10

Truth Table

RT 1 power switch RT 1 power state

open offclosed on

decisions

criterion

A truth table the same information as state diagram, but it is less graphic

2. Decision tables

4. Design/Control 11

Decision Table

A decision table is a truth table with the information rearranged to be more compact when typed

RT 1 power-state decision table

Criteria/Decisions 1 2 #Power switch on F T 2

ResultPower state 1 2

Num of decisions 1 1 2

2. Decision tables

4. Design/Control 12

Value of Decision Tables

Identifies all possibilities Uncovers hidden paths Promotes consistency Provides concise documentation Allows numerical checks for quality

2. Decision tables

4. Design/Control 13

Limits of Decision Tables

Decision tables don’t guarantee that the decisions are right

2. Decision tables

4. Design/Control 14

Number of Decisions

Number of decisions equals the product of the number of choices for each criterion.

Must account for all the decisions A “-” in a decision table means that the decision

table doesn’t care what the value of a criterion is.

2. Decision tables

4. Design/Control 15

Showing the Number of Decisions

RT 1 power-stateNumber 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

Criteria/Decisions 1 2 #Power switch on F T 2

ResultPower state 1 2

Num of decisions 1 1 2

2. Decision tables

4. Design/Control 16

Showing the Number of PathsRT 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.

Criteria/Decisions 1 2 #Power switch on F T 2Power state - - 2

ResultPower state 1 2

Num of decisions 2 2 4

Paths from/to 1 21 1 12 1 1 4

Add current state even though not

needed in example

Show the matrix of paths

2. Decision tables

4. Design/Control 17

Matrix of Paths

Show the number of paths between each state

1 2 31 16 2 02 14 3 13 14 2 2

2

1

3

214

1

14

2

16

3 2

2. Decision tables

4. Design/Control 18

Example 2 (1 of 3)

Two communications states 1. Not established (not est) 2. Established (est)

Not established if power state is off or ability to communicate is false

Established if power state is on and ability to communicate is true

2. Decision tables

4. Design/Control 19

Example 2 (2 of 3)

communications not established

communications established

power state = off orability to communicate = false

power state = on andability to communicate = true

4. Design/Control 20

Example 2 (3 of 3)

Criteria/Decisions 1 2 3 #Power state = on F T T 2Comm OK - F T 2Comm state - - - 2

ResultComm state 1 1 2

Num of decisions 4 2 2 8

Paths from/to 1 21 3 12 2 2 8

Communications state

2. Decision tables

4. Design/Control 21

Guidelines for Control

Use one state diagram for each decision or concept Use one decision table for each diagram Use adjectives to avoid ambiguity Confirm quality of decisions

2. Decision tables

4. Design/Control 22

Canonical Format

Criteria/Decisions 1 2 3 4 5 6 7 8 9 10 11 12 #A,B A A A A A A B B B B B B 2C,D,E C C D D E E C C D D E E 3F,G F G F G F G F G F G F G 2

ResultState 1 1 1 1 1 1 2 2 3 4 5 5

Num of decisions 1 1 1 1 1 1 1 1 1 1 1 1 12

Example canonical format

2. Decision tables

4. Design/Control 23

Rules for Ordering Criteria

Listed vertically Based on the author’s guess at the impact of

each criterion on state Strongest criterion at the top Weakest at the bottom

2. Decision tables

4. Design/Control 24

Rules for Ordering Decisions

1. Listed from left to right 2. Weakest criterion change fastest 3. Strongest change slowest

2. Decision tables

4. Design/Control 25

Simplifying the Canonical Format

Criteria/Decisions 1 2 3 4 5 #A,B A B B B B 2C,D,E - C D D E 3F,G - - F G - 2

ResultState 1 2 3 4 5

Num of decisions 6 2 1 1 2 12

Example canonical format

2. Decision tables

4. Design/Control 26

Rules for Simplifying

1. Find columns in which criteria have no effect 2. Merge such columns into a single column 3. Replace the values of the criteria that have no

effect with a “-”.

2. Decision tables

4. Design/Control 27

Guidelines for Creating a DT (1 of 2)

1. Identify all states 2. Identify all criteria 3. Identify all values of each criterion 4. Enter the criteria values into the

table in canonical format

2. Decision tables

4. Design/Control 28

Guidelines for Creating a DT (2 of 2)

5. Determine state corresponding to each column

6. Simplify the decision table 7. Confirm the number of decisions

2. Decision tables

4. Design/Control 29

Order of the Criteria Rows

Order of the rows can be changed Number of columns may change

2. Decision tables

4. Design/Control 30

Simplifying

Not necessary to simplify Minimizing makes printing the decision table

easier and helps definition and implementation

2. Decision tables

4. Design/Control 31

Optimization

Row order resulting in fewest number columns is not always obvious

Obtained by trial and error

2. Decision tables

4. Design/Control 32

Invariance

Number of decisions and the path matrix remain the same

Confirms accuracy of rearranging rows

2. Decision tables

4. Design/Control 33

Changing Rows

Changing rows doesn’t leave table in canonical format

2. Decision tables

4. Design/Control 34

Making Columns Mutually Exclusive

The columns must be mutually exclusive

2. Decision tables

4. Design/Control 35

Violation of Mutual Exclusive

Criteria/Decisions 1 2 3 # 1 2 3 4 5 #A,B A - B 2 A A A B B 2C,D - C D 2 C D C C D 2

ResultState 1 2 3 1 1 2 2 3

Num of decisions 2 2 1 5 1 1 1 1 1 5

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 hand Right hand

2. Decision tables

4. Design/Control 36

Additional Results Information

Criteria/Decisions 1 2 3 4 # 1 2 3 #A,B A A B B 2 A A B 2C,D C D C D 2 C D - 2

ResultState 1 1 2 2 1 1 2Create error N Y N N N Y N

Num of decisions 1 1 1 1 4 1 1 1 4

Results in addition to state can be shown. However additional information may prevent

merging some columns.

2. Decision tables

4. Design/Control 37

Mechanical Guidelines for DTs

1. Use Excel 2. Use ‘- to enter a minus into a cell 3. Use calculating capabilities to check numbers 4. Use non-proportional fonts 5. Use single character criteria

2. Decision tables

4. Design/Control 38

Example 3 (1 of 5)

Three load states 1. Not loaded or loading 2. Loading 3. Loaded

Determined 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])

2. Decision tables

4. Design/Control 39

Example 3 (2 of 5)

If (1) the comm state is not established or (2) the load status is failure, then the load state is not-loaded-or-loading

If (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

If (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

2. Decision tables

4. Design/Control 40

Example 3 (3 of 5)

not loadedor loading

(1)

comm state = not estor 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 estor load status = failure

comm state = est& load cmnd= load

& load status = not failure

2. Decision tables

4. Design/Control 41

Example 3 (4 of 5)

Criteria/Decisions 1 2 3 4 5 6 7 8 9 10 11 12Comm state F T T T T T T T T T T T 2Load status - F N N N N N C C C C C 3Load command - - N N N S L N N N S L 3Load state - - 1 2 3 - - 1 2 3 - - 3ResultLoad state 1 1 1 2 3 1 2 1 3 3 1 2Num of decisions 27 9 1 1 1 3 3 1 1 1 3 3 54Path 1 to 1 9 3 1 1 1 1 16 1 2 3Path 1 to 2 1 1 2 1 16 2 0Path 1 to 3 0 2 14 3 1Path 2 to 1 9 3 1 1 14 3 14 2 2Path 2 to 2 1 1 1 3Path 2 to 3 1 1Path 3 to 1 9 3 1 1 14Path 3 to 2 1 1 2Path 3 to 3 1 1 2

2. Decision tables

4. Design/Control 42

Example 3 (5 of 5)

Criteria/Decisions 1 2 3 4 5 6 7 #Comm state F - T T T T T 2Load status - F N C N C C 3Load command - - S S L L N 3Load state - - - - - - 2 3

ResultLoad state 1 1 1 1 2 2 3

Num of decisions 27 27 3 3 3 3 1 67

Paths from/to 1 2 31 20 2 2 20 2 13 20 2 67

Problems with developing decision table ad hoc

67>54

2. Decision tables

4. Design/Control 43

Example 4 (1 of 3)

Two operate states 1. Not operating 2. Operating

Determined by Operate command (stop, operate -- [S,O]) Operate state (1, 2-- [1,2]) Load state (not loaded, loading, loaded [1,2,3]

If (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

If the operate command is operate, then the operate state is operating

2. Decision tables

4. Design/Control 44

Example 4 (2 of 3)

not operating(1)

operating(2)

operate command = operate

operate command = stop

4. Design/Control 45

Example 4 (3 of 3)

Criteria/Decisions 1 2 3 4 #Operate command S O O O 2Load state - 1 2 3 3Operate state - - - - 2 ResultOperate state 1 1 1 2

Num of decisions 6 2 2 2 12

Paths from/to 1 21 5 12 5 1 12

2. Decision tables

4. Design/Control 46

3. Data flow

Flow diagrams Automated techniques Terminology Tracing data flow

3. Data flow

4. Design/Control 47

Flow Diagrams (1 of 2)

Flow diagrams show the flow of physical quantities, data, and control into, out of, and through a product. Examples are

Power Cooling air Signals Control

3. Data flow

4. Design/Control 48

Flow Diagrams (1 of 2)

Diagrams can be functional or physical Controlling the flow is one of the strongest

influences a product engineer has on the development of a product

3. Data flow

4. Design/Control 49

Automated Techniques

Excel spreadsheet Data bases; e.g. TeamWork

3. Data flow

4. Design/Control 50

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; e.g., power control. Design develops this concept and creates requirements for

lower products and interfaces. The interface requirements also become requirements for the lower products

requirementsrequirements requirements

requirements requirements

3. Data flow

4. Design/Control 51

4. Instrumentation

Need for instrumentation Embedding instrumentation during design

4. Instrumentation

4. Design/Control 52

Need for Instrumentation

Build and verify activities benefit from instrumentation Customers are wary about depending upon the results

of simulation Customers feel more comfortable with measured data

4. Instrumentation

4. Design/Control 53

Examples of Instrumentation

Time tagging Throughput Trouble shooting Access to unavailable features

4. Instrumentation

4. Design/Control 54

Value of Embedding Instrumentation

Less expensive than adding later Common to leave in the system

4. Instrumentation

4. Design/Control 55

Costs of Instrumentation

Expensive to collect all variables produced by the system and then figure out what to do with the data later

Expensive without stated objective Data reduction expensive

4. Instrumentation

4. Design/Control 56

5. Homework

Problem Six states Determined by Off state Not communicating state Not loaded state Loading state Loaded state Operating state

5. Homework

4. Design/Control 57

Problem

1. Create the decision table for this problem 2. Show the number of decisions for each column 3. Create the path matrix showing the number of

paths between each state and the number of ways for taking each path

Hint -- 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

4. Design/Control 58

Six States

1. Off 2. Not communicating 3. Not loaded 4. Loading 5. Loaded 6. Operating

5. Homework

4. Design/Control 59

Determined by

Power command = on (false, true -- [F,T]) Communication status = OK (false, true -- [F,T]) Load status (failed, none, complete -- [F, N, C]) Load command (none, stop, load -- [N, S, L]) State [1, 2, 3, 4, 5, 6] Operate command (stop, operate [S, O]

5. Homework

4. Design/Control 60

Off State

If the power command is off, then the state is off

5. Homework

4. Design/Control 61

Not Communicating State

If (1) the power command is on and (2) the communication status is false, then the state is not communicating

5. Homework

4. Design/Control 62

Not Loaded State

If (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

4. Design/Control 63

Loading State

If (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

4. Design/Control 64

Loaded State

If (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

4. Design/Control 65

Operate State

If (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