An Obstacle Avoidance and Trajectory Tracking Algorithm for Redundant Manipulator End

Abstract

An obstacle avoidance algorithm was suggested in this study to handle the redundant manipulator’s end trajectory planning problem, with the accuracy of the end trajectory guaranteed to be within the projected error. To accomplish this goal, the calculation method of vector pseudo distance is used instead of the traditional Euclidean distance to express the minimum proximity between the robot arm and the obstacle. This method can express the constraint conditions between the obstacle and the robot arm more clearly and improve the obstacle avoidance efficiency. The virtual repulsion force is generated to make the end of the manipulator far away from the obstacle through the relationship between the velocity vector and the angle vector of the end motion, and the end recovers to the desired trajectory quickly and stably after avoiding the obstacle through the adjustment of the tangent velocity function. The error adjustment coefficient e K is intended to communicate back the actual trajectory of the end obstacle avoidance to the tracking function in real time, and to adaptively change the velocity and acceleration of the end-executor to reduce the end trajectory tracking error. The simulation results show that when an envelope body obstacle appears unexpectedly on the end executor’s expected mission locus, if the expected distance between the endeffector r and the obstacle is greater than or equal to 0.02m, the end of the actuator can avoid the obstacle and return to the expected track quickly and smoothly.