Robust control of flexible joint robots based on motor-side dynamics reshaping using disturbance observer (DOB)

This paper proposes a robust control scheme based on a disturbance observer (DOB) for flexible joint robots. In this paper, the DOB is applied only on the motor-side dynamics of the robot, and the uncertainties on the motor-side are successfully eliminated. It is shown that, to guarantee the stability, the estimated motor-side position should be fed back into the controller, which is different from usual setup of the DOB. The experiments/simulations show that the estimated signal feedback indeed guarantees the stability, whereas the measured signal feedback does not.