Research on Gravity Compensation in Motion Control of Multi-joint Robot

Abstract

Since the robot system is a system with strong coupling and many uncertain factors, there are many problems in the robot control, and the error problem in the process of robot trajectory tracking control is one of the most important problems. This paper proposes a novel gravity compensation method for the six-degree-of-freedom robot. First the kinematics and dynamics models of the robot system are established, and the running trajectory is generated by polynomial interpolation. Then the changes in the gravity workspace in the robot dynamics model and the influence of the gravity moment on the robot pose are analyzed. Based on the establishment of robot dynamics and kinematics model, a gravity feedforward compensation PD control method is designed. In this method, gravity compensation term is introduced on the basis of PD controller, which can effectively solve the tracking error problem caused by the gravity of each joint link of the robot. The simulation results show that the PD control method of gravity feedforward compensation based on the robot model can effectively improve the accuracy of the system trajectory tracking under the premise of the accurate compensation model, and it has good response characteristics and tracking ability.