Augmented timed petri nets for modeling, simulation, and analysis of robotic systems with breakdowns

Flexible manufacturing and assembly systems consists of machines, robots, and automated guided vehicles aimed at meeting dynamically changing market needs. Numerous asynchronous concurrent actions involved in these systems make analysis of them difficult. Breakdowns of system components further complicate investigation of issues related to design, performance optimization, and control. This paper proposes a new class of modeling tools called augmented timed Petri nets (ATPNs) for modeling and analyzing robotic assembly systems with breakdowns. These models aid designers in better understanding the concurrency, synchronization, and sequential relations involved in breakdown handling and in system simulation for performance analysis. A flexible assembly system consisting of three robots with various breakdown rates is used to illustrate modeling, simulation, and analysis with ATPNs. ATPN models for breakdown handling are presented and analyzed for estimating system performance and for designing the optimum number of assembly fixtures. ATPN models can also be used for real-time system control. Finally, possible extensions to this study are discussed.