Contouring Control of Robot Manipulators Based on Equivalent Errors

Abstract

Abstract This work is concerned with the contouring control problem of robotic manipulators using the method of equivalent errors. The method was previously proposed for multi‐axis motion systems with emphasis on machine tools applications. It is shown in this paper that the method of equivalent errors is equally applicable to robot manipulators. For robotic systems, a desired path usually is described in terms of the position of the end‐effector (task space), but the system dynamics are described in generalized coordinates (joint space). The proposed method utilizes the forward kinematics to transform the desired path in the task space into that in the joint space. As such, the equivalent errors can be defined easily. Two examples contouring free‐form paths are studied numerically to demonstrate the effectiveness of the proposed method. One is a two‐link robot manipulator, and the other is a 6‐ DOF Stewart platform. Three controllers for the system with and without uncertainty are considered. The simulation results demonstrate the excellent performance of the proposed method and verify the effectiveness of its application to the contouring control problem of robotic systems, even with uncertainty and higher degrees of freedom.