Torque disturbance rejection in high accuracy tracking systems

The possibility of rejecting torque disturbances that degrade the pointing and tracking accuracy of electromechanical pedestals and general two-axis systems used for target acquisition and robotics is discussed. Torque rejection achieved through disturbance estimation and compensation results in a vast improvement in pointing accuracy. For the class of disturbances considered, comparisons of a classical loop configuration of a tracker, modeled as a two-mass system, with the state-space solution indicate that at least an order-of-magnitude improvement in tracking error can be achieved