Discrete-time H-2/LTR design and analysis of a disk drive actuator tracking servo system

This paper considers discrete-time H-2/LTR design and analysis of a disk dr ive actuator tracking servo system. A discrete-time servo system, which con sists of a current state estimator and a state feedback controller, is desi gned by a discrete-time H-2/LTR methodology. Frequency shaping is introduce d to improve system characteristics such as sensitivity and complementary s ensitivity of a servo system in the desired frequency regions. A state esti mator is designed by minimizing the estimation error in the H-2 sense with given frequency weightings. Subsequently, a state feedback gain is determin ed by a frequency weighted LTR technique at the plant output. The results o f experiments on a commercial disk drive are presented to demonstrate the a pplicability of the proposed H-2/LTR technique.