Modeling for supervisor synthesis – a lock-bridge combination case study

Designing supervisory controllers for high-tech systems is becoming increasingly complex due to demands for verified safety, higher quality and availability, and extending functionality. Supervisor synthesis is a method to automatically derive a supervisor from a model of the plant and a model of the control requirements. While supervisor synthesis is an active research topic, only a few reports exist on industrial applications. One of the reasons for this is the lack of acquaintance of control engineers with modeling and specifying in the framework of automata. In addition to this, there are no clear guidelines for obtaining the necessary models for synthesis. In this paper, we describe a general way of modeling for the plant and the requirements in order to contribute towards the acceptance of supervisor synthesis in industry. This way of modeling is illustrated with an industrial case study in which a supervisory controller is synthesized for the Algera complex. The Algera complex consists of a waterway lock and a movable bascule bridge. The supervisor has to control 80 actuators based on the observations from 96 discrete sensors, in response to 63 control commands available from the operator. We show how to model the plant as a collection of extended finite-state automata, how to model the requirement as a collection of event conditions, how to synthesize the monolithic supervisor, and how to validate the resulting supervisor using continuous-time simulation.