Flexible Manufacturing System Scheduling Using Hybrid Petri Nets with Dispatching Rules

Flexible manufacturing systems (FMSs) are advanced and highly integrated manufacturing systems consisting of robots, machining cells, and automated guided vehicles (AGVs) that function under the hierarchical control of computers. The relations between its components are very complex. Scheduling in FMS is an intricate phenomenon owing to the large variability in the operating parameters. Scheduling problems for general cases are characterized as NP hard and the computation time required to obtain the optimal schedule will grow exponentially with the problem size. Petri nets (PNs) have recently emerged as a promising approach for measuring and analyzing the performance of FMSs. PNs are formal graphical modeling tool that can be utilized efficiently as a modeling and analysis tool. PN can also dynamically simulate and graphically represent a process in an integrated manner. This paper addresses merging of PNs with dispatching rules for measuring the performance of FMSs. Also the system has been modeled in MAT lab integrated Petri net2.3 software and the traditional dispatching rules were also used for the purpose of comparison and verification of the simulation results. Benchmark case studies are chosen and the results show that the PN integrated with dispatching rules provides enhanced result when compared to other two techniques. Index Term-Flexible manufacturing system, Scheduling, Petri net, Dispatching rules, MAT lab petrinet 2.3.