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.
This study addresses the problem of assuring provably safe and correct behaviour of safety-critical complex hybrid systems (CHS) throughout their life-cycles when physical system dynamics tend to change due to natural causes. Model-based development methods are needed that integrate formal specification, verification, implementation level testing and runtime validation. Scalability limitations of available algorithms/methods dictate a modular approach, but this poses conflicting issues of compositionality, falsetransitivity, soundness and completeness. In this paper a compositional solution approach based on the decomposition and hybridisation of statechart models (into hybrid automata-HA) is demonstrated. Specifically, a compositional formal verification methodology developed earlier for discrete event dynamic systems (DEDS) was elevated to hybrid dynamics, successfully overcoming the risk of false transitivity common to direct abstraction methods of continuous state-space. It was then used to develop a scalable strategy to generate sound and complete (relative to coverage criteria) tests, and configure corresponding compositional HiL tests for different abstraction and functional levels. The same decomposition was used to derive compositional runtime validation tests based on discrete invariants and differential invariants. The study formally proves that (1) the proposed HA based formal verification method is compositional, sound and complete relative to first-order logic of differential equations, (2) the modular tests are compositional and (3) the HA based test generation method is compositional, sound and complete relative to firstorder logic of differential equations. To reduce complexity compositionality is rendered parallel than sequential to perform the simpler tasks concurrently. The claims have been validated experimentally on a full scale experimental rig.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.