An elastic force based collision avoidance method and its application to motion coordination of multiple robots

Abstract

A key contribution of robots to a manufacturing system is flexibility and automation. The robots can handle part batches of varying size and mix and can adapt to process variations and uncertainties in the working environment. This paper proposes a method for the collision-free motion coordination of multiple robots in a common working environment. The method uses an improved elastic force based method for collision avoidance. For the motion coordination of multiple robots, prioritisation-and-avoidance is used. Priority is assigned to each robot with a robot of lower priority avoiding the robots of higher priority. Without priority, every robot takes pains to avoid all the other robots. This degrades the overall performance of the coordinated motion. In addition, priority allows a robot with an urgent job to perform its job quicker. For collision avoidance, elastic force as well as potential field force is used. Compared with the method using only the potential field force, the robot can keep its configuration while avoiding other robots. Moreover, by adjusting the elastic force, task-consistent motion is possible. This method is tested by simulation and results in a smooth and adaptive coordination in an environment with different types of robots. Also the proposed method is compared with a method using the conventional elastic strip based method. The method can be used to coordinate the motion of multiple robots in a common working environment of a CIM system without interference.