Patent ID: 10073444

Abstract:
Since single and dual-arm tools behave differently, it is difficult to coordinate their activities in a hybrid multi-cluster tool that is composed of both single- and dual-arm tools. Aiming at finding an optimal one-wafer cyclic schedule for a treelike hybrid multi-cluster tool whose bottleneck tool is process-bound, the present work extends a resource-oriented Petri net to model such system. By the developed Petri net model, to find a one-wafer cyclic schedule is to determine robot waiting times. By doing so, it is shown that, for any treelike hybrid multi-cluster tool whose bottleneck tool is process-bound, there is always a one-wafer cyclic schedule. Then, computationally efficient algorithms are developed to obtain the minimal cycle time and the optimal one-wafer cyclic schedule. Examples are given to illustrate the developed method.