External torque-sensing algorithm for flexible-joint robot based on Kalman filter

The external torque estimation problem in a 1-degree-of-freedom flexible-joint robot system with a joint torque sensor is revisited. The flexible-joint robot has two dynamics, motor-side and link-side dynamics, making the problem more complicated. An external torque-sensing algorithm for the flexible-joint robot is proposed, which treats these two dynamics simultaneously for extracting external torques applied to the system. The basic structure of the proposed algorithm is illustrated, and the performance is verified by a custom-designed experimental apparatus for vertical configuration with a gravitational load.