Based On Petri Nets Distributed Multi-agv Path Planning And Collision Avoidance Research

Path planning and block avoiding are key technologies to finish resource transmission in auto factory. Auto guided vehicle have been used partly in CIMS or FMS aboard. How to control these distributed AGV (Auto Guided Vehicle), and make it finish transfer mission with high efficiency, so to make the auto-factory become more flexible, will be the urgent problem to solve we face now. From this we know it is important to investigate method of path planning and block avoiding.In this paper, we work mainly on investigation about multi-AGV path planning and block avoiding. After we compare several modeling method and tools, we find that Petri nets has been an important tool to analysis these problem. Doctor Carl Adam Petri had created this net theory about forty years ago. After learning the theory carefully, and try to solve some simple problem using it, we find it have many virtue to control complicated system with it. So we choice Petri net as the modeling and analysis tool to help us solve distributed AGV path planning and block avoiding. First we use Petri net to modeling AGV in Flexible manufacture system, describe every AGV as an intelligent object that have some ability about decision-making. In path planning, AGV's action was looked as transition, whether an action should happen was decided by transition rule. When we know the start place and destination, serial actions make up the AGV's path.In this paper, a new concept, related place was introduced. AGV and other object such as machine tool and storeroom, all could be describe by the new concept. Use this new concept, a block could be described by several places, these places make up a new related place, so we could use it to find appropriate path and avoid block at the same time. In block avoiding, the main theory used is contacting freeness. We transfer the collision as resource contact, so some theory of Petri net could be use to avoiding the block.At the end of paper, a simulation program has been designed to test the method introduced above. In order to describe the real method, multi-thread technique and critical section in MFC was use here. From the program simulation, the validity of method was proved.