Orccad Control Architecture

Transcription

1 In Proceedings of the 9th ESA Workshop on Advanced Space Technologies for Robotics and Automation 'ASTRA 2006' ESTEC, Noordwijk, The Netherlands, November 28-30, 2006 Orccad Control Architecture K. Kapellos TRASYS R. Pissard-Gibollet, D. Simon, B. Espiau INRIA Rhone-Alpes 1

2 ORCCAD: A Three- Layered Control Architecture Decision Layer: Plans Discrete Event Systems Plans correct by construction Execution Layer: Tasks Event based specification Deterministic behaviour Formal methods and tools Functional Layer: Actions Automatic control theory Efficient real-time implementation 2 2

3 Plan Functional Layer Actions Tools Execution Layer Task Tools Decision Layer Concepts Tools 3 3

4 Functional Layer Action definition An Action is defined as the complete and parameterised specification of: A control law A local behavior rythmed by events Temporal constraints Examples: move_mast_to(), take_image(), Algorithmical part Wait a request to start Wait preconditions Activate the control law Wait and handle exceptions Until the post-conditions are satisfied Deactivate the control law START_Action ABORT_Action Behaviour Action_GoodEnd Action_handle_exc_k 4 4

5 Functional Layer Action Implementation Real-Time Multi-rate, multi-task Implementation Computation durations Activation period Priorities Assigned processor 5 5

6 Functional Layer The Actions specification Tool Development under Eclipse Plug-in for specification and code generation, connections with external modelling tools,. Use of XML format for data specification 6 6

7 The Execution Layer Decision Layer: Plans Execution Layer: Tasks Start_A1, Abort_A1,, Exceptions_A1 Functional Layer: Actions Start_An, Abort_An,, Exceptions_An 7 7

8 Execution Layer Task Definition Task is defined as a logical and temporal composition of Actions and Tasks. Examples: CriticalDeployment, Travel, Drill, do [ DrillMoveTo (); CloseImagerMoveTo (); [ CloseImagerMonitor() DrillExtractSample() ] ] watching Alarm do. 8 8

9 Execution Layer Formal Framework Reactive systems inputs Reactive system outputs Behavior of the system All allowed sequences of the input/output events Synchronous approach The duration of the system reaction is negligible wrt the input signal occurrences ESTEREL language Dedicated for reactive systems programming Compilation to finite state automata Tool for simulation, verification and code generation 9 9

10 Execution Layer The FORMID Tool Specification Selection of Actions/Tasks Provide the ESTEREL code that specifies the sequencing of the involved Actions/Tasks Esterel modules definition, declarations, are automatically produced 10 10

11 Execution Layer The FORMID Tool Task Simulation and Formal Verification Relationship between Actions/Events and Actions The execution of the Action/Task A1/T1 triggers is always preceded by always takes place during always implies the execution of the Action/Task A2/T2 The occurrence of the Event event triggers the execution of the Action/Task A2/T

12 Fault detection and Recovery Decision Layer: Plans exc type 3 replanning Execution Layer: Tasks exc type 2 exc type 2 exc type 2 Functional Layer: Actions exc type 1 exc type 1 exc type

13 Decision Layer: Supervisory Control Theory Objective : Create a new sequence of Tasks (a Plan) in case of a (re)-planning request ensuring its correctness wrt a set of constraints Models: Discrete Event Systems Properties & Objectives: Transition systems that express constraints on the behaviour of the system Events: distinguished between controllable and uncontrollable Derivation of a controller such that the resulting behavior of the closedloop system meets the control objectives u controller system c X system objective Does the system satisfy the objective? objective 13 13

14 Decision Layer: The basic entities Decision Layer Model of the System Controller Synthesis component Controller Execution component Execution Layer: Tasks Task 1 Task n 14 14

15 Decisional Layer: Tools Supremica [Prof. K. Akesson Chalmers University] HMI for generating the model of the system, the constraints and the objectives Algorithms to synthesise the controller (monolothic, BDD based and compositional) 15 15

16 Orccad and Associated Supervision Tools Linked with the generated code via DREAMS 16 16