Deadlock avoidance in semiconductor track systems

Addresses the deadlock avoidance problem in track systems in semiconductor fabrication. Without buffer space in it, the existing deadlock avoidance policies tend to be too conservative. Routing flexibility provides a chance to develop better ones, but makes their computation more complex. The paper models a track system using colored resource-oriented Petri nets. Based on the model, a sufficient condition for deadlock-free operation and the corresponding control law are presented. The proposed policy is shown to be computationally efficient. An example is presented to demonstrate its application.