Supervisory control synthesis for a waterway lock

Formal methods help in coping with the growing functionality and complexity, time-to-market and costs in cyber-physical systems (CPSs). Supervisory control synthesis (SCS) is such a method. It can be used to synthesize a controller for a CPS from the uncontrolled system model (plant) and the specification model (requirements). While SCS is an active research topic, reports on industrial applications are rare. In this paper, we show the applicability of SCS to the design of controllers for waterway locks. The following steps in the development process are discussed: modeling the plant and the requirements, synthesizing the supervisor, validating the supervisor, generating a real-time controller and implementing this controller on a PLC. Following this way of working, a supervisory controller for a real waterway lock has been successfully developed and analyzed. The real-time controller is implemented in an experimental set-up. The state-space size of the uncontrolled plant is 6.0 χ 1032 and the number of state-based requirements involved in the specification is 234. The synthesized controller is automatically translated into 1.2 χ 104 lines of structured text, executable by a PLC. This case study delivers a proof of concept for the applicability of the procedure for supervisor synthesis and automatic PLC code generation to industrial-size systems.