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.