Compensation for external vibration impact on the positioning accuracy of hard disk drives is considered with the presence of actuator uncertainty in this paper. The low-frequency mode change due to actuator pivot nonlinearity of the voice-coil-motor (VCM) actuator is described as frequency and damping uncertainty. A robust feedforward controller is then designed in continuous time domain by using H{sub}∞ method to attenuate the impact with the aid of a sensor to detect external vibrations. The linear matrix inequality (LMI) approach is adopted to solve the robust H{sub}∞ feedforward control design problem. The application results in a 1.8-inch disk drive with an accelerometer to measure acceleration signal show that 27% to 91% reduction of the position error signal is achieved with the robust feedforward controller when the frequency changes in 70±50 Hz and damping in 0.4±0.3. The effectiveness of the robust feedforward control is also demonstrated to be better than nominal feedforward control.
展开▼
