| Budget Amount *help |
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 2006: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2005: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Research Abstract |
A micro-actuator will be important technology to achieve high-speed and highly precise head positioning control for hard disk drives. In conventional hard disk drives, a voice-coil motor (VCM) actuates the suspension, positioning the slider over the desired data track. Structural resonance modes of the head stack and suspension assembly are one of the major limiting factors for achieving higher head-positioning servo performance in hard disk drives. A suspension assembly in the hard disk drive (HDD) can be excited by the airflow generated from a high-speed rotating magnetic disk, a non-circular track motion of the head/slider, which is caused by the resonance vibration modes of components, and other external disturbances. A servo system that can cope with these problems requires a very high servo bandwidth and position error signal sampling frequency. The sampling frequency of the position error signal is limited by the data storage efficiency of the conventional servo system. Active c
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ontrol of these problems and the vibration of components require additional vibration sensors and actuators. Many researchers have proposed the addition of extra vibration sensors and actuators. For example, the use of a piezoelectric actuator to actuate the suspension for the dual-stage servo system has been proposed, whereby one of the two piezoelectric strips is used as a vibration sensor and the other is used as the actuator. However, using only half of the conventional micro-actuator pair as the sensor decreases the usual effect of the actuator by half and is not efficient.
In this project, self-sensing control of a micro-actuator for the hard disk drive is presented. The micro-actuator is a suspension driving type. The micro-actuator uses a PZT actuator pair, installed on the assembly of the suspension. The self-sensing micro actuator can be used to form a combined actuation and sensing mechanism. Feedback control results of direct velocity feedback (DVR) and direct position feedback (DPF) and positive position feedback (PPF) are presented and compared. The objective of the experiments are to verify the feasibility of these self-sensing approaches as a vibration suppression control of the micro-actuator. Artificial neural networks can be used effectively for the identification and control of nonlinear dynamical systems, such as a flexible micro-actuator with a suspension assembly and a self-sensing system. In the present project, in order to solve these problems and improve the performance of the dual-stage servo system for the HDD, a self gain tuning neural-network control has been proposed by utilizing the self-sensing sensors to damp the suspension assembly vibrations. Less
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