关键词: 柔性制造系统, 死锁预防, Petri网, 信标, 广义互斥约束

Abstract: To solve the problem of deadlock prevention for System of Simple Sequential Process with Resources (S3PR),a policy to design the deadlock-free supervisor with the maximum permissive system was proposed based on siphons.Using the iterative method,a set of Generalized Mutual Exclusion Constraints(GMEC) were added into all emptiable Strict Minimal Siphons (SMS) existed in the net system so as to make the number of siphons constrained in a given up-limited value,which transformed the siphon based deadlock prevention strategy into the monitoring problem of forbidden state.Thus all forbidden states in the controlled net system could not be reached,and the controlled network had maximum permissive behavior.The effectiveness of proposed policy was verified by examples of flexible manufacturing system,and it was especially suitable for the net model with relatively simple structure and high quality requirement of the reachable states.

Key words: flexible manufacturing systems, deadlock prevention, Petri nets, siphon, generalized mutual exclusion constraints