Inside the Stateflow 4

Transcription

1 State Flow 1

2 What is StateFlow? Stateflow is a graphical design and development tool for control and supervisory logic used in conjunction with Simulink. It provides clear, concise description of complex system behavior using finite state machine theory 2

3 Example 3

4 Inside the Stateflow 4

5 Events/Data Input event on_switch rising_edge event off_switch falling_edge data temp Output data y 5

6 Example The Stateflow has 2 states: Power_on and Power_off. When the state machine is first turned on, we will use the default transition. The default transition will turn to the initial state in this case Power_off state. When we change the manual switch from Off to On, the model sends an event (on_switch), that makes the change from Power_Off state to Power_on state When we change the manual switch from On to Off, the model sends an even (off_switch), that makes the change from Power_On state to Power_off state 6

7 Stateflow Stateflow is an example of finite state machine. A finite state machine reacts to events by changing states. 7

8 Flow Diagram Stateflow also adds the feature of flow diagram that provides decision points in transition 8

9 Explain A junction has been added to the diagram that checks to see if the outside temperature is less than 30 degree. 9

10 Stateflow Objects 10

11 State Hierarchy Stateflow supports the representation of graphical object hierarchy. 11

12 Example The diagram is the parent of Car_done The state Car_done is the parent of Car_made and Car_Shipped The state Car_made is the pareant of Parts_assembled and Painted 12

13 Texture representation The texture representation of the hierarchy of object is as follows: /Car_Done /Car_Done.Car_made /Car_Done.Car_shipped /Car_Done.Car_made.Parts_assembled /Car_Done.Car_made.Painted 13

14 Representing State Transition 14

15 State Decomposition Exclusive (OR) state Parallel (AND) state 15

16 Exclusive (OR) State Exclusive OR decomposition is used to describe system model that are mutually exclusive. From the example, either state A or state B can be active. If state A is active, either state A1 or A2 can be active at any one time 16

17 Parallel (AND) State The children of parallel (AND) decomposition parents are parallel states. All states at the same level are always active at the same time. In the following example, when state A is active, A1 and A2 are both active at the same time. 17

18 Example In the following example, when state A becomes active, both states B and C become active at the same time. When state C becomes active, either state C1 or state C2 can be active. 18

19 State Label Notation The label for a state appears on the top left corner of the state rectangle with the following format: name entry: entry actions during: during actions bind: events, data exit: exit actions on event_name: on event_name actions 19

20 Example 20

21 State Name A state label starts with the name of the state Valid state names consist of alphanumeric characters and can include underscore(_) The use of hierarchy provides some flexibility in the naming of states. 21

22 Hierarchy Example Ride1.On Ride1.Off Ride2.On Ride2.Off 22

23 State Actions Entry Action: preceded by the prefix entry. In the previous example, we set on_count = 0 whenever state On becomes active During Action: preceded by the prefix during. In the previous example, state On has two during actions, light_on() and on_count++. These action are executed when state on is already active and any event occurs 23

24 State Actions Exit Action: preceded by the prefix exit. In the previous example, state Off has the exit action light_off(). If state Off is active and becomes inactive, this action is executed. On Event action name: preceded by the prefix on event_name.. In the previous example, state On has an on power_outage action. If state On is active and the event the power_outage occurs, the action handle_outage is executed. 24

25 State Actions Bind action: preceded by the prefix bind. In previous example, the data on_count is bound to state On. Other states can use the data, but cannot change the value. Only state On or a child of state On can change the value of data on_count 25

26 Transition A transition is a curved line with an arrowhead that link one object with another. The source state is where the transition begins, and the destination is where the transition ends. 26

27 Example of Transition 27

28 Transition Junctions divide a transition segments Each segment is evaluated in the process of determining the validity of full transition 28

29 Transition Label Notation The label consists of an event, a condition, a condition action, and a transition action event [ condition]{condition_action}/transition_action 29

30 Example 30

31 Connective Junction 31

32 Transition Notation Event: causes the transition to be taken. Specifying an event is optional Condition: is a Boolean expression to specify that a transition occurs given that the specified expression is true. Condition Action: follows the condition for a transition. It is executed as soon as the condition is evaluated as true. Transition Action: is executed, once the transition is completed (reached). 32

33 Transition to and from Exclusive states 33

34 Transitions to and from Junctions 34

35 Transitions to and from Exclusive Superstates 35

36 Transitions to and from Substates 36

37 Self-Loop Transitions 37

38 Before Using an Inner Transition 38

39 Inner Transition After using E_one inner transition 39

40 Using an Inner Transition to a History Junction History junction is used to remember the previous state 40

41 Default Transition 41

42 Default Transition to a Junction Example 42

43 Default transition with a Label 43

44 Connective Junction Provide more efficient generated code and optimize memory use 44

45 Connection Junction- Self Loop 45

46 For Loop Example 46

47 STMF4 Example: Traffic Light 47

48 Example 48

49 Questions? 49