Algorithmische Synthese ereignisdiskreter Steuerungen mit erweiterten Petrinetz-Modellen

• Algorithmic Controller Synthesis for Discrete Event Systems with Extended Petri Net Models

Bollue, Kai Dominik; Abel, Dirk (Thesis advisor); Thomas, Wolfgang (Thesis advisor)

Aachen (2018)
Dissertation / PhD Thesis

Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2018

Abstract

The thesis addresses the synthesis problem of discrete event controllers based on a plant model and both safety and goal constraints. For the plant model Petri nets are used, with test, inhibitor and event arcs as additions. During modeling, places are marked as observable or non-observable while transitions are marked as controllable or non-controllable. A central concept is the use of Linear Marking Constraints for the description of marking sets. After basic definitions, properties and algorithms for their modification and simplification, Linear Marking Constraints are used for various purposes during the proposed synthesis procedure: First, the transformation of a given plant model into an Abstract Net is described, during which all processes possible in the original model and initiated by the controller are mapped to Abstract Transitions with equivalent preconditions and results. For the description of these Abstract Transitions' preconditions, as well as for the simplification of the created Abstract Net, Linear Marking Constraints are used. Non-controllable processes in the plant are substituted by Abstract Transitions already during the transformation of the model. Linear Markings Constraints are also the basis of the subsequently proposed approach for a symbolic reachability analysis which is used to derive legal firing sequences in the Abstract Net. Based on these legal firing sequences, a control algorithm is generated which drives the plant from a given initial state to a state fulfilling the goal constraints while enforcing the safety constraints. Finally, some application examples are presented, including parts of the model plant at the Institute of Automatic Control, RWTH Aachen University.