An effective deadlock prevention policy using elementary siphons of Petri nets for FMS

This paper largely presents a deadlock prevention policy for automated flexible manufacturing systems. Based on Petri nets and some investigations on siphons, this policy is targeted at one modeled manufacturing system extended from system of simple sequential process. Given a net, elementary and dependent siphons can be obtained from the strict minimal siphons. Our deadlock control method is an iterative one by adding two kinds of control places called ordinary control place and weighted control place to the original net to prevent elementary siphons from being unmarked, under some conditions the dependent siphons can be prevented from being emptied as well. Finally, a flexible manufacturing example is presented to illustrate our deadlock prevention policy.