Use of MEMS based accelerometers in hard disk drives

In this paper we describe the use of MEMS based accelerometers for the compensation of the effects of self-induced and external vibrations in commercial hard disk drives (HDD). Using a formal analysis on the HDD mechanics, the effects of a generic roto-translation of the HDD on the head position are evaluated. It is also shown that such effects can be compensated by using a feedforward compensation which makes use of a weighted sum of the signals provided by a pair of linear and one rotational accelerometer, properly placed on the HDD´s body. As for the rotational acceleration, this has been obtained by using a recently developed MEMS-based, low-cost rotational accelerometer. Experimental results presented here show that a 20 dB reduction on a commercial HDD can be achieved with a simple, variable gain feedforward compensator. Effective reduction is achieved up to 200 Hz