CROTPN Based Collision-Free and Deadlock-Free Path Planning of AGVs in Logistic Center

Abstract

In recent years, automated guided vehicle (AGV) is becoming increasingly important for logistic center, which usually has tens of thousands of express packages to sort and transport every day. In order to enhance the efficiency of sorting, multiple AGVs have been used to transport as many express packages as possible in a given time. However, there may exist collisions and deadlocks when two or more AGVs are trying to pass through a shared area at the same time. In this paper, we study collision-free and deadlock-free path planning of multiple AGVs with the objective of minimizing the makespan, that is, the maximum time of the AGVs to finish a round of delivery. To solve the problem, we first propose a candidate path generation algorithm to generate several paths for each AGV, from which a combination of the paths is selected based on optimal path combination selection (OPCS) algorithm, such that the collisions and deadlocks can be minimized. Then, we construct a colored resource-oriented timed Petri net (CROTPN) model for dynamic changing AGV routes after slicing the scheduling period into timeslots. Through Slot-Control policy, the collision and deadlock can be effectively avoided. Our experiment is simulated based on CPN tools. Experiment results show that our method can achieve a high sorting throughput using the least AVGs.