Trajectory Control of Robot with Flexible Joints Using Torque Feedback Control and Feed-Forward Control. Improvement of Trajectory Tracking Accuracy on SCARA Robot Driven by Stepping Motor.

Abstract

Robot arms vibrate during trajectory control because of the flexible joints. We have already proposed the method of torque feedback control of a robot with flexible joints in order to suppress the vibration of robot arms. This method only takes into consideration the torsional angle caused by vibration, but not the torsional angle to transmit torque to links. Thus it does not realize improvement of the trajectory tracking accuracy. Therefore we attempt to compensate this torsional angle to transmit torque by means of feed-forward control. We propose a method of trajectory tracking control which includes both torque feedback control and feed-forward control in order to improve the trajectory tracking accuracy. In experiments, we use the trial SCARA robot which has flexible joints and is driven by stepping motors. It is shown that the proposed method is effective in improving the trajectory tracking accuracy.