Algorithm of Path Planning Based on Time Window for Multiple Mobile Robots in Warehousing System

Abstract

Automation of goods transportation in warehousing system is essential to improve productivity and reduce costs for the modern logistic enterprises. Under this background, automatic warehousing is becoming a key to logistic systems due to its ability of scheduling and optimizing delivery tasks of robots and, consequently, increasing productivity and decreasing costs. This paper firstly describes briefly problems needed to be solved for working of multiple mobile robots in automatic warehousing systems. Then, we build a map model based on topological graph for the warehouse environment and choose a storage representation of adjacent matrix for it. This paper details the algorithm of task scheduling and path planning for multiple mobile robots in warehousing system. The presented algorithm applies the ${\mathrm {A}}^{*}$ shortest-path method to solve path planning problem of single robot and, further, introduces time window approach to solve traffic jams and collisions of multiple robots. Computer simulation tests were conducted to compare the efficiency of the ${\mathrm {A}}^{*}$ algorithm with other shortest-path methods of path planning for single robot. For logistics scenario of multiple robots, routing simulations were also carried out to verify performance of the purposed algorithm under different working conditions. Test results showed that the algorithm could generate collision-free and optimized paths for multiple mobile robots.