Adaptive-Robust Control for Dual-Stage Hard Disks
With the aim to increase storage capacity of magnetic hard-disc drive systems (HDD-systems) in particular the track-per-in value, dual-stage actuated HDD-systems have been of interest for many years. Dual-stage actuator systems, comprising a voice-coil-motor (VCM)-actuator for coarse actuation and a high bandwidth PZT-actuator, have been an attractive alternative to the commercially used single VCM-actuator system. Since they allow for higher servo bandwidth and more accurate positioning of the read/ write head. Designed as high bandwidth actuator with small displacement of less than 2 micrometers, different types of high bandwidth secondary actuators have been introduced, mounted on the VCM-actuator, either on the suspension, head or slider. Servo-control in HDD comprises three different tasks. One of the tasks is track following, during which data is written or read from one of the concentric tracks on a hard disk. For track following, linear control structures are usually used. The second task of HDD-servo control is track seeking for which often non-linear control methods or special control methods involving path planning are employed. The transition between the two control tasks, track seeking and track following, is usually achieved by the task of track settling to prevent large overshoots. In this research we first introduce structure of HDD-systems and need for increasing of accuracy for its control system. In chapter 2 we introduce various structures of micro actuators and their mathematical models. Then in chapter 3 we introduce various structures of control for this system. In chapter 4 and 5 we introduce ARC controller structure and design and simulate this structure on HDD Dual Stage systems with compensator prefilter respectively.
|2005||M.Sc.||Dynamical Systems Analysis and Control|