High Backdrivability Control Based on Estimation of Shaft Torsion in R/C Servo Motor

Abstract

This paper proposes high backdrivability control which can be applied to inexpensive R/C servo motors. This control method is constituted by shaft torsion control and admittance control. In shaft torsion control, the motion of the robot is derived from shaft torsion. Shaft torsion is estimated by using Shaft Torsion Observer(STOB). On the other hand, in admittance control, the motion of the robot is derived from reaction force. Reaction force is estimated by using Reaction Force Observer(RFOB). These control methods are selectively used depending on the movement of the motor. By using the proposed method, backdrivability of the R/C servo motor was improved in comparison with conventional admittance control.