Structural Analysis of GRAFCET Control Specifications

TL;DR

This paper introduces a structural analysis method for GRAFCET control specifications that approximates variable states to enable verification of industrial control designs, handling concurrency and large state spaces effectively.

Contribution

It presents a novel analysis approach combining step analysis and Petri net techniques to verify GRAFCET specifications at the design level.

Findings

Capable of verifying behavioral errors in industrial-sized examples

Handles large state spaces due to concurrency in GRAFCET

Effective for practical plant specifications

Abstract

The graphical modeling language GRAFCET is used as a formal specification language in industrial control design. This paper proposes a structural analysis that approximates the variable values of GRAFCET to allow verification on specification level. GRAFCET has different elements resulting in concurrent behavior, which in general results in a large state space for analyses like model checking. The proposed analysis approach approximates that state space and takes into consideration the entire set of GRAFCET elements leading to concurrent behavior. The analysis consists of two parts: We present an algorithm analyzing concurrent steps to approximate the step variables and we adapt analysis means from the field of Petri nets to approximate internal and output variables. The proposed approach is evaluated using an industrial-sized example to demonstrate that the analysis is capable of verifying behavioral errors and is not limited by the specification size of practical plants.