Patent ID: 7595956

Claim:
A method for controlling a dual-stage actuator comprising a primary actuator and a secondary actuator, said dual-stage actuator comprising a primary actuator servo loop for controlling the motion of the primary actuator and a secondary actuator servo loop for controlling the motion of the secondary actuator, said method comprising: generating an actuator motion based on a primary actuator motion and a secondary actuator motion; generating a position error signal based on said actuator motion and a system disturbance; in said primary actuator servo loop, generating a primary actuator controller input signal based on summing said position error signal and an estimated secondary actuator motion signal, and sending said primary actuator controller input signal to a primary actuator controller for generating a primary actuator control signal; in said secondary actuator servo loop, generating a secondary actuator controller input signal based on said primary actuator controller input signal, said estimated secondary actuator motion signal, and a secondary actuator controller reference limit, and sending said secondary actuator controller input signal to a secondary actuator controller for generating a secondary actuator control signal; wherein said secondary actuator controller reference limit corresponds to the maximum physical stroke of said secondary actuator.