MingZhong Ding

Low Frequency Vibration Detection and Compensation in Hard Disk Drive

The paper proposes a control scheme for detecting and compensating the low-frequency vibrations in hard disk drive systems. A vibration detector is proposed, utilizing the down-sampled position error signal (PES). Due to the performance limitation in loop shaping, attenuating low-frequency vibration is usually penalized by high frequency disturbance amplification. This paper proposes an adaptive scheme to intelligently adjust a vibration reduction factor, such that when vibration level is low, the servo loop maintains its normal operation mode, and little or no compensation is carried out. Experiments on hard disk drives on a vibration shaker validated the effectiveness of the proposed compensation scheme.

Servo Systems Using Multi-rate Notch Filters To Attenuate Resonances Beyond Nyquist Rate

This paper presents a systematic computation method of discrete-time plant response based on the continuous-time bode measurement, also proposes a 2times multi-rate notch filter to attenuate the resonant mode higher than sampling rate

Modeling the Smpled-data System with a discontinuous Hold for Hard Disk Ramp Loading

This paper deals with modeling of the hard disk ramp loading with a discontinuous controller. The property of the sampled-data system with a discontinuous hold is studied. Further, explicit expression of the discrete-time transfer function of sampled-data systems with a discontinuous hold is provided for a class of continuous time plant. It is shown that with discontinuous hold, the hard disk plant sampled-time model is minimum-phase instead of non-minimum phase if with zero-order hold

Effective Low Frequency Disturbance Feed Forward Compensation Scheme for Mobile HDD Application

The advantage of low cost and large capacity gives strong driving force for hard disk to enter the consumer electronic market. One of the most challenging servo control issue faced in mobile application is to perform normal read/write operation when significant vibration is excited in HDD jogging/walking condition. This paper presents a simple yet effective method to improvement hard disk throughput with an add-on low frequency disturbance feed forward compensator. With the proposed approach, the track following performance is significantly improved in jogging/walking, and the hard disk is capable to meet the read/write throughput requirement with minimum servo controller re-design effort