Output feedback seek control for disc drives with Lipschitz nonlinearities

The effects of magnetic latch and data flex bias on seek control of a hard disk drive actuator are investigated. The magnetic bias latch replaces the more expensive solutions currently used in industry and provides improved reliability. The overall bias torque is nonlinear and present throughout the entire actuator stroke thereby affecting seek performance. The bias can, however, be represented by a function that is Lipschitz within the actuator sweep angle. A stable, certainty equivalence, output feedback seek controller is designed to handle the effects of bias. Extensive experiments were conducted and the controller was evaluated for various seek lengths