An Approach Dealing with Wrist Singularity of Six-DOF Industrial Robots

This paper presents an engineering method for analyzing the kinematics and inverse kinematics of a kind of Six-DOF industrial robots. Firstly, we build an engineering coordinate system for this kind robot, and then get expressions of closed-form solutions to both kinematics and inverse kinematics. From the process of deducing the expressions of closed-form solutions, we can analyze common singularities existing in workspace. Lastly, we design programs for both kinematics and inverse kinematics and simulate the movement of this kind robot. This method, compared with the structures of traditional solutions, is easier and understandability by leading into two conceptions- the position end and the tool end. What is more significant is that the robot can move safely when the wrist is under the singularity by using transitional stage. The transitional stage can make the tool of the robot move a line without join angel sudden change. The program solves the problem that all domestic industrial robots can not move when the wrist is under the singularity. This program is realized successfully on the welding robot of SIASUN Corporation.