Precision positioning and shock resistance of hard disk drives using piezoelectric actuators with passive damping. ; CUHK electronic theses & dissertations collection

Hard disk drives (HDDs) are the most important information storage devices for computers. Positioning precision is crucial to today's increasingly high-speed, high-capacity, high data density, and miniaturized HDDs. Therefore, the demand for higher bandwidth servo systems that can quickly and precisely position the read/write head on a high track density becomes more pressing. Recently, the idea of applying dual-stage actuators to track servo systems has been studied. The push-pull piezoelectrically actuated devices have been developed as micro actuators for fine and fast positioning, while the voice coil motor functions as a large but coarse seeking. However, the current dual-stage actuator design uses piezoelectric patches only without passive damping. In this thesis, a dual-stage servo system using enhanced active-passive hybrid piezoelectric actuators is proposed. The actuators improve the existing dual-stage actuators for higher positioning precision and better shock resistance, due to the incorporation of passive damping in the design. The main aim is to develop this hybrid servo system not only to increase the speed of track seeking but also to improve precision of track following servos in HDDs. A new piezoelectrically actuated suspension with passive damping is designed and fabricated for precision positioning of the head while reducing undesirable vibrations. In order to evaluate positioning and track following performances for the dual-stage track servo systems, tasks carried out in the thesis are: (1) to investigate the damping abilities and transmissibilities of the active-passive hybrid micro actuators; (2) to investigate the shock resistance of the dual-stage piezoelectric actuators with passive damping; (3) to implement the synthesized active-passive suspension with enhanced piezoelectric actuators using a composite nonlinear feedback controller. ; Chan, Kwong Wah. ; "December 2006." ; Source: Dissertation Abstracts International, Volume: 68-08, Section: B, page: 5512. ; Thesis (Ph.D.)--Chinese ...