GA based reduced order robust loop shaping controller design for HDD servo system with dual stage actuator

As we know that the recording density is increasing at an impressive annual rate of 100%, and the access time is decreasing; very soon, the storage density of Harddisk drive will cross 1 Terra bit per square inch. The VCM actuator used in the conventional disk drives has hundreds of flexible resonances at high frequencies, which limit the increase of bandwidth and hence the positioning accuracy. In order to develop a high band width(track-following) servo system, dual-stage actuator has been proposed as a possible solution to this problem. This paper proposes the design of fixed-structure robust loop shaping control for a dual stage actuator system, which is a class of multi input single output system (MISO). The design is based on the concept of robust control in multivariable feedback. The discussion between the proposed controller and the conventional parallel and decoupled Master slave structure is included in this paper. Simulation results verify the effectiveness of the proposed technique.