Simulation and analysis of discrete-event control systems based on Petri nets using PNetLab

Supervisory control based on Petri Nets (PNs) or Colored Petri Nets (CPNs) model of the plant leads to supervisors which can be PN/CPN themselves (compiled supervisors) or simply a set of logical predicates (interpreted supervisors). There is a lack of simulation and analysis tools that can be used in both cases and can support the development of supervisors. In this paper PNetLab is presented, a simulation and analysis tool developed by the Automatic Control Group of the University of Salerno. It allows drawing of a PN/CPN model by a graphical user interface and the definition of the supervisor as a PN/CPN or as a standard C/C++C/C++ program implementing logical predicates. Functionalities to analyze the closed-loop model with all kinds of supervisors (PN/CPN/logical predicates) are available (token game and coverability tree) as well as standard functionalities when both the plant and the controller are PNs (P-invariants, T-invariants, minimal siphons and traps computation). In addition, PNetLab includes management of time (plant modelled by timed PNs/CPNs) and conflict management so as to permit testing of scheduling strategies together with the supervisor as required in performance optimization problems. Finally, the tool's simulation engine can be linked from an external program allowing look-ahead supervisory techniques. The tool is available free of charge for interested readers.