Robust Digital Tracking Controller Design for High-speed Positioning Systems

In this paper, a design approach for robust digital tracking controllers for high-speed positioning is proposed. In high-speed tracking, the combination of a feedforward controller and a robust feedback controller is desirable: the robust feedback controller compensates for mechanical nonlinearities, parameter variation, and disturbances and lets the dynamic behavior of the actual feedback loop system stay close to the nominal one, which makes it possible for the feedforward controller to correctly anticipate and compensate for closed loop dynamics. The idea of disturbance observers is utilized to construct a robust feedback system, and is combined with the idea of zero phase error feedforward controllers. The overall system is demonstrated to possess excellent tracking performance by simulation and experiment.