Statechart based modeling and controller implementation of complex reactive systems

Abstract

Statechart formalism has been a preferred choice for modeling complex reactive systems (CRS) in recent years. It has inbuilt powerful features of orthogonality, hierarchy, intermodular communication and history. Once statechart based system modeling is done the next issues to be addressed are (1) modular verification of the system for failsafe operation under all possible working conditions (2) progressive controller implementation together with the supervisory control while maintaining traceability and re-configurability and (3) facilitation of controller adaptation for progressive incorporation of security features and supervisory specifications. An elevator system was designed and built to reflect exigencies of a typical CRS hardware/software platform. A controller was designed to meet the above requirements and tested on the platform to validate the feasibility of model-based control design/verification methodology for real scale systems. Modularity was achieved by developing the statechart model of the plant into a tree of communicating language generators. Progresively verified modules were then translated into sequential function charts (SFC) which were finally integrated to form a complete flat SFC. The SFC was then implemented on a PLC platform (Telemechanique). The program was first validated in simulation using Telemechanique “Twidosuite” for different operating conditions and finally tested on the elevator system.