Path planning for automated guided vehicle systems with time constraints using timed Petri nets

Zhou He,Chan Gu,Yuying Dong,Gongchang Ren,Zhiwu Li

doi:10.1177/0020294020964840

Abstract

Automated guided vehicles (AGVs) are extensively used in many applications such as intelligent transportation, logistics, and industrial factories. In this paper, we address the path planning problem for an AGV system (i.e. a team of identical AGVs) with logic and time constraints using Petri nets. We propose a method to model an AGV system and its static environment by timed Petri nets. Combining the structural characteristics of Petri nets and integer linear programming technique, a path planning method is developed to ensure that all task regions are visited by AGVs in time and forbidden regions are always avoided. Finally, simulation studies are presented to show the effectiveness of the proposed path planning methodology.

Highlights

With the rapid development of Industrial 4.0, automated guided vehicles (AGVs) have been extensively employed to handle complicated tasks efficiently
We show that an AGV system and its static environment can be modeled by timed Petri nets (TPNs)
Given a path requirement u that contains logic and time constraints discussed in Section ‘‘Path planning for AGV systems using PNs’’, we aim to find an optimal trajectory of the AGV system such that all task regions are visited by AGVs in time and forbidden regions are always avoided, while the total travel distance is minimized

Summary

Introduction

With the rapid development of Industrial 4.0, automated guided vehicles (AGVs) have been extensively employed to handle complicated tasks efficiently. Given a path requirement u that contains logic and time constraints discussed in Section ‘‘Path planning for AGV systems using PNs’’, we aim to find an optimal trajectory of the AGV system such that all task regions are visited by AGVs in time and forbidden regions are always avoided, while the total travel distance is minimized. Since the path requirement for AGV systems considered in this paper is different from the one in Mahulea and Kloetzer, we propose some methods to transform the logic and time constraints into a set of linear constraints. Considering the path planning problem for the AGV system discussed in Section ‘‘Problem statement’’, we assume that a task region pj should be visited by at least one AGV along the trajectory (if pj 2 Pt) or at the final state (if pj 2 Pf). The logic constraint on the trajectory [7] can be transformed into a set of linear constraints as follows:

À vpj Á

Declaration of conflicting interests