A Flexible Multiple Mobile Robots System

Abstract

Optimal performance of a manufacturing layout consisting of several mobile robots performing specific transportation tasks depends on effective task planning. For mobile robots of a specific type and a structured workplace layout, task planning aims to achieve a maximum throughput of robot trips by coordinating robot motion to minimize congestion in the system. This, in turn, minimizes the number of robots required to carry out a specific work load. In this paper, a novel, synergistic approach based on decentralized path planning, heuristic algorithm based navigation, and localized collision avoidance is presented. A comprehensive, flexible multiple mobile robots system (MMRS) consisting of standard patterns, a local controller, and individual mobile robots has been described. The mobile robots are capable of performing their own path planning and collision avoidance by means of ultrasonic sensors, standard patterns, and rotary optical encoders. Specially designed algorithms for the mobile robot and the local controller have been presented. To ensure greater flexibility in designing the layout, the proposed MMRS was interfaced with a specially designed CAD subsystem. Simulations using varying numbers of robots were performed on a sample layout that was designed using the CAD subsystem. A statistical analysis of the simulation results was performed to evaluate the control algorithms and to determine the optimal number of robots required for the designed layout. The results of the simulation have been presented to illustrate the validity of the approach. © 1992 IEEE