US Patent 7400468 Vibration detector for hard disk drives

A hard disk drive with a circuit that provides a control signal to a voice coil motor to move a head across a disk. The disk drive includes a circuit that provides a control signal to the voice coil motor to move the head. The circuit also has a state predictor and an inversion filter that compute a vibration estimate used to detect a vibration in the drive. When a threshold vibration is detected a vibration estimate is combined with the control signal to compensate for the vibration. The circuit detects the vibration without the need for an accelerometer or other sensor.