Robust Fast Seek Control of a Servo Track Writer Using a State Space Disturbance Observer

Unknown and uncertain disturbances significantly affect the servo performances of servo track writers. Therefore, the development of a robust fast seek controller that seeks using a state space disturbance observer is required. We present the design and application of a robust fast seek controller for servo track writers. Unlike some existing methods that use an explicit model for disturbance or for adjusting sensitivity using a filter, the proposed method is shown to effectively compensate for disturbances even while track seeking, which is not possible when using an integrator or a frequency domain disturbance observer. Experimental results demonstrate the utility of the proposed robust fast seek controller, which uses a state space disturbance observer, for servo track writers. The proposed servo track writer control scheme seeks tracks quickly in the presence of unknown and uncertain disturbances.