Multi-sensing servo with carriage-acceleration feedback for magnetic disk drives

A multi-sensing servo with a carriage-acceleration feedback to improve the sector servo in a magnetic disk drive has been designed. To increase the control bandwidth, the multi-sensing servo reduces the peak gain of a carriage mechanical-resonance, and there is no phase-lag up to near the control bandwidth. A carriage mechanical-resonance model is introduced that includes both the bending mode of a carriage arm and the elastic deformation mode of a pivot bearing. In place of a notch-filter circuit, the carriage-acceleration feedback controller has been implemented in an analog circuit. And experimental results show that the developed acceleration feedback controller is more effective for controlling head position than a usual sector-servo controller with a notch filter.