Model-matching solution for optimal positive joint torque feedback

Applying positive joint torque feedback in direct drive motor systems reduces the effect of external load torques. This is most beneficial when accurate position tracking is required in the presence of large disturbances or for complex loads as found in robotic manipulators. We formulate the problem of torque feedback in the presence of actuator dynamics. The problem of finding the optimal torque feedback which minimizes the maximum disturbance sensitivity is equivalent to the model-matching problem. The effect of the load on the rotor dynamics appears as a perturbation minimized by the proposed torque feedback. To synthesize the torque filter, only the actuator dynamics and a very rough knowledge about the mechanical load is required