Commutational ramp load control for disk drive actuators

The research investigates the feasibility of a ramp load/unload (L/UL) controller using a conventional, non-L/UL disk drive actuator. Therefore, disk drives with lower cost and higher torque actuators can realize the linear shock resistance benefits of ramp loading. A disk drive designed with a conventional actuator is outfitted with a ramp and optimized for L/UL operation. While on the ramp, there exists a set in the state space where the actuator dynamics are uncontrollable. A state trajectory is generated that, when tracked, moves the actuator through the uncontrollable set and equilibrium points for a successful load onto the disk at the desired load velocity. A continuous, state-feedback controller with varying gains is designed for tracking. A unique disk drive is manufactured with ramp load capability and experiments are performed to verify the design and modeling results.