TIME-OPTIMAL SEEK CONTROL FOR A COUPLED DUAL STAGE DISK-DRIVE ACTUATOR

A unified expression and three typical kinds of seeking trajectories o f the time optimal control of a dual stage disk drive actuator with pa ssive coupling between the two stages are presented. Necessary conditi ons for finding the optimal control for the problem with state-variabl e constraints are applied to derive the solution. Numerical calculatio ns and computer simulations were performed to get the trajectories. Th e experimental trajectories of 1/3 full stroke for a disk drive are al so presented. A DSP (Digital Signal Processor) based control system is used to implement the optimal control. The time optimal seek control features cooperative control of the two stages of the actuators, and s eek time can decrease as compared with one-stage seeking when the fine actuator locked onto the coarse actuator.