Predictable Design for Real-time Embedded Control A Case Study Jinfeng Huang & Jeroen Voeten Eindhoven University of Technology PROGRESS

2 Contents A running example: railroad crossing A running example: railroad crossing Problems in current design practice Problems in current design practice Compositional design approach Compositional design approach Demo Demo

3 Railroad Crossing Trains run independently at different velocities Velocities are constant Avoid collisions As efficient as possible

4 Current Practice Train ACrossing Train B D T T+D+  Start Motor Crossing Area Critical Zone Sensor A Delay (D) Check Crossing Stop Motor

5 Timing Property (Timed) execution trace of “Train A”:  1 +  2   ? SensorA signaled T Delay D T+D Check Crossing T+D+  1 Stop motor T+D+  1 +  2 Between D and D+  seconds after Train A has passed Sensor A, “Train A” checks the Crossing and stops the train if the Crossing is occupied

6 Timing Property - Add other Components e.g. to control other trains or crossings. (Timed) execution trace of “Train A” (disturbed by other components):  1 +  2 +  3 +  1 +  2   BOOM !!! SensorA signaled T Delay D T+  1 +D Check Crossing T+  1 +D +  2 +  1 Stop motor T+  1 +D +  2 +  1 +  3 +  2 Other components running T+  1 T+  1 +D+  2 T+  1 +D +  2 +  1 +  3

7 Problems in current practice Behaviors of components are not compositional Debug and analysis codes “pollute” the timing behavior of the system Lack reusability, maintainability, portability etc. Lack facilities to guarantee property preservation: Implementation exhibits unexpected behaviors not present in the model Lack facilities to guarantee property preservation: Implementation exhibits unexpected behaviors not present in the model

8 Compositional Approach (Modeling) Based on a two-phase execution frame: actions are instantaneous and time progress is represented in a virtual way (instead of based directly on a physical clock) POOSL: Based on a two-phase execution frame: actions are instantaneous and time progress is represented in a virtual way (instead of based directly on a physical clock) Compositional semantics Compositional semantics Executable Executable Expressive (concurrency, time, Expressive (concurrency, time, communication…)

9 Compositional Approach (Modeling) Abstract Model Refinement Verification Extended Model Simulation Refinement Estimation of  Synthesis Synthesis Model Train A Image Train B Image Crossing LEGO DACTA Interface

10 Compositional Approach (Synthesis) Automatic code generation ( RT-Rotalumis,C++) Real-time property-preserving mapping guaranteed by the  -hypothesis The execution tree: ordering of actions is kept from model to implementation Synchronization between virtual time and physical time: if an action happens at virtual time t in model it happens in physical time interval (t-  /2,t+  /2) in implementation

11 Demo: The Railroad Crossing Velocity TrainA: 40 cm/s Velocity TrainB: 90 cm/s Extended Model Synthesis Model Realization Rapid analysis Abstract Model Models and video are not included in the presentation. For those who are interested, please mailto:

12 Future Work and Open Issues Mapping efficiency Prediction  / platform requirements Multi-processor platforms Streaming data Continuous-time environmental models Tools