Collision detection algorithm for robot manipulator based on momentum deviation observer

Abstract

In view of the fact that robots are easy to collide with humans or obstacles which go into its workspace,a collision detection algorithm based on generalized momentum deviation was proposed to improve the safety of robots. According to the decoupling performance between generalized momentum and external torque of manipulator,a momentum deviation observer was firstly designed to obtain the impact force. Then,a performance regulating function was introduced to improve its dynamic response characteristics. Once impact force was detected,it is possible to judge whether the collision occurred. With this algorithm,collision can be detected in real time,and can effectively avoid the influence of acceleration or deceleration,without any additional external sensors or acceleration of the manipulator,simply by measuring the motor current and the position got by encoders of each joint. Simulation and experiment results show that the algorithm has reached the expected requirements in real- time performance. And the disturbances caused by accelerating and decelerating of manipulator are also very small. Moreover,it provides an approximate position and direction of the impact force which has important significance for further security reaction control.