Design and simulate event-driven systems. modes. modes 4. left positions control points. hydraulic pressures

Transcription

1 Stateflow 6 Design and simulate event-driven systems Stateflow is an interactive design and simulation tool for event-driven systems. Stateflow provides the language elements required to describe complex logic in a natural, readable, and understandable form. It is tightly integrated with MATLAB and Simulink, providing an efficient environment for designing embedded systems that contain control, supervisory, and mode logic. Stateflow charts enable the graphical representation of hierarchical and parallel states and the event-driven transitions between them. Stateflow augments traditional statecharts with the innovative capabilities of control flow, MATLAB and graphical s, truth tables, temporal operators, directed-event broadcasting, and support for integrating hand-written C code. You can automatically generate C code from Stateflow charts using Stateflow Coder (available separately). KEY FEATURES Provides language elements, hierarchy, parallelism, and deterministic execution semantics for describing complex logic in a natural and understandable form Defines s graphically, using flow diagrams; procedurally, using the MATLAB language; and in tabular form, with truth tables Schedules transitions and events using temporal operators Incorporates custom and legacy C code with input and output arguments Supports vector, matrix, and fixed-point data types Provides viewing and logging of states and data Animates Stateflow charts to enhance understanding of the system and facilitate debugging Performs static checks, including checks for ill-specified truth tables Performs run-time checks for transition conflicts, cyclic problems, state inconsistencies, data-range violations, and overflow conditions Includes an integrated debugger for setting graphical breakpoints, stepping through models, and browsing data {} {1} elev_pos pos_bus {1} Signal Conditioning and Fault Detection low_press <low_press> LDL_mode R_pos_fail <R_pos_fail> L_pos_fail <L_pos_fail> Mode Logic {1} {1} modes left positions control points <Left positions> right positions <Right positions> Pilot Commands and Control <hydraulic pressure> modes control points elevator positions hydraulic pressures Hyraulic Acutators and Elevators { The fault detection, isolation, and recovery system of an aircraft elevator. You can use Simulink and Stateflow to simulate and study the effects of switching modes on the control system and aircraft dynamics.

2 x Switch [Input_1] [Tick_In1] _In rt_popping Select] In Pop #1 [_Out_1] [_1] _Out_1] _Out_] _Out_] Vert Cat [5x1] U [Dest1] [Tick_Out1] [Dest1] Dummy Event FIFO Out #1 {} [Input_] [Tick_In] In art_popping_ Pop # _Select] [_Out_] [_] _Out_] 0 [Dest] [x1] U(E) emu [Dest] [Tick_Out E [Dest] 1 [Dest] AutoPush Dummy Event #1 Crossbar Queue {} Empty Simulink model of a packet switch used in data networking applications. Stateflow defines the queue and control logic for the FIFO. [Input_] [Input_] Contents: 1) 9 ) Total length (>=5) ) Destination ) Source 5) Data (Integer) : Length-1) Data (Integer) Length) 0 [Tick_In] rt_popping Select] [Tick_In] rt_popping Select] [Input_1] [Input_] [Input_] [Input_] [Dest1] [Dest] [Dest] [Dest] Working with Stateflow Stateflow is part of an integrated simulation environment in which you can model, simulate, and analyze complex dynamic systems. By using Stateflow with Simulink, you can create models of your embedded software that combine the logical behavior (such as fault detection and mode switching) with the algorithmic behavior (such as feedback control and signal conditioning). You can also create a model of the system and its environment in Simulink and run hybrid simulations to study the interactions between the two. In Pop In Pop # # [_Out_] [_] [_Select] after(lenin1,tick)... [x] NonEmpty s Start_Popping {State.Pushed;} [Tick_Out] [_Out_] Scheduler [Dest] 1/z In In Dummy Event Pop # [_] en:queue.push; Tick{Queue.Push;} {} 0 [Start_Popping_1] Push[!in(Queue.Full)]{EnQueue();} Input 1 Input Input Input Output 1 Output Output Output Logic on tick: switches(); Stop / go.neutral(); EndStop Idle AtTop / go.down(); Remain in Stop state until a event triggers Stop.Mode to be Ready. Position NotSureWhere AtBottom / go.up(); Error Selector Mode Waiting 1 Ready [in(attop)] NearBottom after(_70ms,tick) NearTop [in(direction.down)] Temp en:queue.push; [Tick_Out [Dest] Dummy Event Tick{LenIn=DataIn;} 0 [Start_Popping_] emu [Start_Popping_] [Tick] [Start_Popping_] AutoPop [Tick_In1] [Tick_In] Global [Tick_In] Cloc Idle [Tick_In] In en:queue.pop; Start StartPopping [Which==My_Number] {UsingSwitch=1; State.NotReady;} after(lenout,tick) {State.Popped;} Tick/Queue.Pop; Fail safe time out after continuous movement of more than five seconds after(failsafe_timeout,tick) UP DOWN DOWN UP FIFO Out # Pop[!in(Queue.Empty)]{DeQueue();} {} [Tick_Out1] [Tick_Out] [Tick_Out] [Tick_Out] State Empty Nees gap of between packets Ready LenOut=[LenLoc]; Dst=[DstLoc]; Pushed {Nums++;} [in(ready)] truthtable switches() Move entry: obstacles.init(); on tick: obstacles.detect(); go() obstacles() Direction DOWN Down / 1 [~in(down)] go.down(); Error [strt==end] [strt==end] DeQueue EnQueue UP [~in(up)] Up / go.up(); [in(manual)] [after(_1s,tick)] Mode en(direction.up)... en(direction.down) EmergencyDown / NotSureYet go.down(); Auto OBSTACLE ENDSTOP after(_1s,tick) [after(_00ms,tick)... & before(_1s,tick)] Manual Full Pushed {Nums++;} NotReady [Nums==0] Popped {Nums;UsingSwitch=0;} NotReady Pushed {Nums++;} Driver Up Driver Down Convert (SI) IaADC driver_up driver_down moveup DOC Requirements Stateflow chart of the control logic for a power window system. Passenger Up passenger_up movedown Passenger Down passenger_down Motor_and_Electronics Obstacle Window_Switches Control obstacle Test Cases position velocity force Window_Mechanics Obstacle_Effects Visulization Simulink model of the same system, incorporating the electric motor (modeled in SimPowerSystems) and the window mechanism (modeled in SimMechanics) to determine the load on the motor and enable the logic to detect obstacles in the window s path.

3 Creating Stateflow Charts A Stateflow chart is a graphical representation of a finite state machine where states and transitions form the building blocks of the system. You create a Stateflow chart by dragging states, junctions, and s from the toolbar into the drawing window. You can then create transitions and flow by connecting states and junctions together. You can reduce a complex chart to a set of simpler, hierarchically organized diagrams by using subcharts. A truth table is used to implement the logic to select a valid sensor reading in a faultdetection algorithm. Stateflow features several interactive tools for creating and modifying charts. These include: A Stateflow diagram editor that provides shortcut menus, navigation and command toolbars, zoom controls, and other productivity enhancers A Symbol Autocreation Wizard that lets you define nongraphical objects A debugger that controls animation of your Stateflow charts and provides extensive capabilities for examining simulation results and locating and diagnosing unexpected behavior in your Stateflow chart Stateflow uses the Model Explorer in Simulink to create data, events, and targets and to navigate, search, and configure the attributes of all Stateflow objects. Adding Functions Stateflow lets you include s within your statechart. You can define and use three types of s: Graphical s let you graphically program an algorithm and track its behavior during simulation. Embedded MATLAB s let you call MATLAB s for data analysis and visualization. You can also use an embedded subset of the MATLAB language to define embedded, matrix-oriented algorithms. Truth tables let you specify s with combinational logic in a concise, tabular form without drawing flow diagrams. You can control the execution of Simulink -call subsystems from Stateflow, letting you call Simulink subsystems like a. You can also incorporate existing hand-written C code s into your Stateflow chart. Heater Off entry: turn_boiler(off) on every(5,sec): flash_led() em turn_boiler(mode) flash_led() [LED==OFF] after(0,sec) after(0,sec) [cold()] {LED=OFF} {LED=color} [Heater.On.warm()] On b = cold() { b = temp<=reference} Stateflow chart defining the logic for a boiler temperature control system that uses temporal logic to ensure that the boiler does not overheat. An embedded MATLAB (above) and graphical s (right side of chart) implement utility algorithms called by the heater system (left side of chart).

4 The Model Explorer lets you navigate, create, configure, and search all data, events, and attributes of your Stateflow chart, as well as create an interface with Simulink. Specifying Temporal Logic Conditions Stateflow employs an event-scheduling mechanism that generates accurate and efficient code for event-driven systems. You can use temporal operators ( before, after, at, and every ) to specify scheduling logic for transition and state activities. These temporal logic conditions operate on occurrence counts of Stateflow events, freeing you from the error-prone event-scheduling tasks of handling timers and counters. Creating Chart Libraries By creating a chart library in Stateflow, you facilitate chart reuse. For example, when you update a chart in a library, all instances of the chart are automatically updated. Interfacing with Simulink You can exchange events and data with Simulink by simply: Adding and defining input and output events and data for your Stateflow chart in the Model Explorer Connecting the Stateflow input and output ports to Simulink blocks Defining simulation parameters in Simulink You can also define an interface between a Stateflow block and code sources external to the Stateflow block and Simulink model. State Transition Sens_Failure_Counter 1 MultiFail FL0 FL1 FL FL FL Parallelism History Action Fueling_Mode Running Low_Emissions entry: fuel_mode = LOW Normal [in(fl1)] H H Rich_Mixture entry: fuel_mode = RICH Single_Failure [ speed > max_speed ] [!in(multifail)] Fuel_Disabled Hierarchy Condition [in(fl0)] enter(multifail) Junction [in(fl1)] Warmup [in(o_normal)] exit(multifail) Subchart The logic for a fault-tolerant fuel system, defined using several key Stateflow elements. Supertransition

5 Executing Stateflow Charts After modeling your logic in Stateflow, you can simulate and view its behavior live to test and validate your design. A graphical debugger helps you resolve simulation run-time errors and diagnose unexpected behavior in your design. Visualizing Results You can visualize the Stateflow chart during simulation by: Highlighting the active states and the transition paths taken Viewing states and data with the displays and scopes provided in Simulink Building your own custom displays using MATLAB visualization and graphical user interface development tools You can also log states and data for postprocessing. Debugging a Simulation The Stateflow debugger lets you set breakpoints, control the simulation execution, and display model information. It can be run from a graphical user interface (GUI) or from the MATLAB command line. The GUI provides clear information about the chart s execution status. You can display information on breakpoints, current data values, active states, and the call stack. Run-time errors can also be detected with the debugger. These include state inconsistencies, transition conflicts, data range, potential infinite loops, and ill-specified truth tables. Using the floating scope from Simulink, you can view state transitions as the simulation runs.

6 The Stateflow debugger can set breakpoints, start and stop simulations, evaluate run-time errors, and perform dynamic error checking. Validating your Design You can map requirements directly to Stateflow objects and collect model coverage metrics using Simulink Verification and Validation (available separately). Generating Code Stateflow charts can be deployed to many applications using Stateflow Coder (available separately). Required Products MATLAB Simulink Related Products Real-Time Workshop. Generate optimized, portable, and customizable C code from Simulink models Simulink Verification and Validation. Develop designs and test cases mapped to requirements and measure test coverage Stateflow Coder. Generate C code for Stateflow charts For more information on related products, visit Platform and System Requirements For platform and system requirements, visit For demos, application examples, tutorials, user stories, and pricing: Visit Contact The MathWorks directly US & Canada Benelux +1 (0) France + (0) Germany +9 (0) Italy +9 (011) Korea +8 (0) Spain Sweden +6 (8) Switzerland +1 (0) UK + (0)1 00 Visit to obtain contact information for authorized MathWorks representatives in countries throughout Asia Pacific, Latin America, the Middle East, Africa, and the rest of Europe. Tel: info@mathworks.com 997v05 05/0 00 by The MathWorks, Inc. MATLAB, Simulink, Stateflow, Handle Graphics, and Real-Time Workshop are registered trademarks, and TargetBox is a trademark of The MathWorks, Inc. Other product or brand names are trademarks or registered trademarks of their respective holders.