Robust loop shaping H/sub /spl infin// control of servo systems

Loop shaping H/sub /spl infin// control with normalized coprime factorization was applied to a servo-motor driven precision positioning system. The high-gain controller was designed to attenuate the position errors caused by friction effects. The non-existence of limit cycle was analyzed, though there is actuator saturation. The designed H/sub /spl infin// control system was experimentally tested in a rotary index table. Results showed its effectiveness to improve position accuracy without any compensation scheme for friction, and robustness to model perturbation and external disturbances.