Iterative identification of state-dependent disturbance torque for high-precision velocity control of servo motors

We present a computationally very efficient learning control method which is ideally tailored to high-precision velocity control of servo motors in the presence of the disturbance torque which is unknown, unstructured, and state-dependent. The proposed learning control method can drive the steady state velocity error to zero and, furthermore, can be used to identify the unknown disturbance torque in look-up table form. In order to demonstrate the generality and practical use of our work, we present the rigorous convergence analysis of the learning control algorithm and some experimental results using a single degree-of-freedom manipulator.