摘要:
A method is disclosed for recursively determining repeatable runout (RRO) cancellation values in a disk drive having a head disk assembly (HDA) and a sampled servo controller. The HDA includes a disk having distributed position information in servo wedges, a rotary actuator carrying a head that periodically reads the position information, and a voice coil motor circuit that responds to a control effort signal. The servo controller periodically adjusts the control effort signal during a track-following operation. In the method, resonant filter values for developing RRO cancellation values are iteratively learned and updated after each disk rotation during track following operations on a predetermined track until a threshold, such as a particular number of disk rotations, is obtained.
摘要:
A disk drive is disclosed comprising a disk and a head actuated over the disk. A burst metric is generated in response to a burst read signal. The burst metric comprises at least one of an alpha metric comprising a ratio of a first burst amplitude of a first phased based servo burst measured at a first radial offset to a second burst amplitude of a second phased based servo burst measured at a second radial offset, a harmonic metric comprising a ratio of a first harmonic of the burst read signal as the head is moved radially over the disk to a higher harmonic of the burst read signal as the head is moved radially over the disk, and a spiral track crossing metric comprising a first and second interval each representing a partial duration of the read element crossing a spiral track.
摘要:
A disk drive is connectable to a power supply voltage and includes a spindle motor, a spindle motor driver, a spindle motor controller, and a detector. The spindle motor has windings and a rotatable rotor. The spindle motor driver is connected to the windings and connectable to the voltage. The spindle motor controller commands the spindle motor driver to apply the voltage across at least one of the windings to cause the rotor to rotate, which induces a BEMF having a polarity across each of the windings. The spindle motor controller subsequently commands the spindle motor driver to remove the applied voltage across the windings, and the detector monitors the BEMF in each of the windings to detect the polarity of the BEMF in each of the windings to generate a previous multi-bit sequence representing a previous phase position ({circumflex over (&thgr;)}n) of the rotor and subsequently detect a change in the polarity of the BEMF in one of the windings to generate a present multi-bit sequence representing a present position (&thgr;n) of the rotor. The spindle motor controller is responsive to the previous phase position ({circumflex over (&thgr;)}n) and the present phase position (&thgr;n) of the rotor for selecting an initial commutation state for commanding the spindle motor driver to initiate a spin-up commutation sequence starting from the selected initial commutation state such that the voltage is sequentially applied across a selected combination of the windings in order to spin-up the spindle motor to an operating spin-rate.
摘要:
A system and method for processing track identifier errors to mitigate head instability in data storage devices is disclosed. The system and method includes computing a track id differential between an expected track id and a received track id, encoding the expected track id and the received track id, initiating a first action if the track id differential exceeds a pre-determined threshold and the encoded expected track id varies from the encoded received track id by a pre-configured number of bits, and initiating a second action if the track id differential does not exceed the pre-determined threshold or the encoded expected track id does not vary from the encoded received track id by a pre-configured number of bits.