Backdriving controling for robotic joint based on equivalent resistance

Aiming at the difficulty of preoperative manual adjustment of minimally invasive surgical robot, a backdriving control method was proposed for a simplified robotic joint. The equivalent resistance model of the joint was built and the dynamic parameters of the system were identified by experiments. A state observe was designed to obtain accurate velocity and acceleration of the joint, and simulation was made to choose proper feedback matrix for the state observer. The backdriving control method was implemented by combining the estimated state values with the equivalent resistance model. Experiment results show that the control method can effectively compensate for gravity, friction and inertial torque during the backdriving process, reducing the average value of adjusting torque by over 70%, and that the stick-slip is diminished during the motion of the joint.