Robust digital tracking controller design for high-speed positioning systems

In this paper, a robust digital tracking controller for high-speed positioning is proposed. For high-speed tracking problems, the combination of a feedforward controller and a robust feedback controller is desirable, because the feedforward controller anticipates and compensates for closed-loop dynamics and the feedback controller compensates mechanical nonlinearities, parameter variations, and disturbances. A disturbance observer and PD compensation was used as a robust feedback controller and a zero-phase error-tracking controller was used as the feedforward controller. This method was applied to an X-Y table, and experimental results demonstrate that this method yields excellent tracking performance and robustness to plant parameter variations.