Synthesized fault-tolerant supervisory controllers, with an application to a rotating bridge

Designing supervisory controllers for high-tech systems is a laborious and error-prone process. Model-driven software engineering methods can help in increasing the quality and productivity by automation of various steps in the design process. Supervisory control synthesis (SCS) is such a method. SCS is a formal method that can be used to synthesize a supervisor for a system from the uncontrolled plant model and the requirements model. Subsequently, this supervisor can be used to generate controller code. While SCS is an active research topic, reports on industrial applications are rare. One of the main reasons for this is that until recently synthesis techniques were unable to scale to industrial-size problems. Due to advances in computation power, memory availability, and synthesis algorithms, synthesis techniques have matured to a point where they are capable of being applied to industrial-size problems. This paper presents a method for modeling, synthesis, validation, code generation, and implementation of fault-tolerant supervisory controllers. To illustrate this method, a case is described where a supervisory controller for a movable bridge has been synthesized, validated, implemented, and tested. With this case study, it is shown that synthesis techniques have reached a critical point where they are powerful enough to be applied in practice.