Robust Performance Verification of Adaptive Robust Controller for Hard Disk Drives

An adaptive robust controller (ARC) has been recently developed for read/write head embedded control systems of hard disk drives (HDDs). This structure is applicable to both track seeking and track following modes, and it makes the mode switching control algorithms found in conventional HDD servosystems unnecessary. An Improved Desired Compensation ARC (IDCARC) scheme is proposed in this paper, in which the traditional ARC is powered by a dynamic adaptive term. In this approach the adaptation regressor is calculated using reference trajectory information. Moreover, a robust analysis of this method is developed, in which a controller designed based on a simple model of the system is verified in a closed loop performance of a more comprehensive model of the system. The simulation result verifies the significant improvement of the performance of IDCARC compared to that of ARC and its robustness for this model. It is observed that in the presence of large disturbances the proposed method preserves the stability and a suitable performance while the ARC fails even in stability.