Synchronous programming in control

Synchronous Programming in ControlPaul CaspiVerimag (CNRS)A historical perspective based on the observation of severalreal world systems during the Crisys Esprit project: The Airbus “fly by wire” system. Schneider’s safety control and monitoring systems for nuclearplants. Siemens’ letter sorting machine control,and many other distributed safety critical control systems.Overview The Origins of Synchronous Programming Synchronous Programming and Real Time Real Time Validation Understanding Synchronous Programming in ControlThe Origins of Synchronous Programming Basic needs of the domain Real time asynchronous languages Synchronous practices The formalisation of these practicesBasic Needs of the Domain Parallelism:– between the controller and the controlled device– between the several degrees of freedom to be controlled atthe same time Guaranteed bounds :– on memory– on execution times DistributionThe Computer Science Answer:Real Time Kernels and LanguagesBased on the concurrency tradition of operating systems: Synchronisation: semaphores, monitors, sequential processes, Communication: shared memory, messages, Synchronisation + communication: queues, rendez vous.Examples: CSP, OCCAM, ADA tasking real time OSThe Evolution of PracticesFrom analog boards to computers:AnalogBoardClock periodic clockssynchronous programsA/D Computer D/APeriodic Synchronous Programminginitialize state;loop each clock tickread ...