Supervisory Control Synthesis for Safety PLCs

The development of supervisory controllers for cyber-physical systems is a laborious and error-prone process. Supervisor synthesis enables control designers to automatically synthesize a correct-by-construction supervisor from a model of the plant in combination with a model of the control requirements. Subsequently, the controller code can be generated from the supervisor model such that it can be implemented on a programmable logic controller (PLC). In industry, supervisors have to adhere to strict safety standards. To achieve these standards, safety PLCs (SPLCs) are used. For SPLC implementation, the supervisor has to be split into a regular part and a safety part. This paper presents a method to automatically splits a supervisor model for this purpose. To validate the method, a case study on a rotating bridge has been performed. The result is compared to a splitting result made by experts. Furthermore, the supervisor has been implemented to control the real bridge.