Servo-free velocity estimator for coil driven actuator arm in a data storage drive
AssigneeInternational Business Machines Corporation
InventorsBryan S. Rowan, Louis Joseph Serrano
Life of this patent
Estimating the term…
Abstract
A system and method for determining the velocity and/or position of a coil driven actuator arm without the aid of servo signals. A sample-hold unit is used to measure no-motion coil voltage in the voice motor coil while applying a predetermined coil current. Then, while the same magnitude (opposite direction) current is applied to move the actuator arm, the coil voltage is measured. The coil voltage is reduced by the measured no-motion coil voltage, producing a measurement of back-emf. The back-emf may be amplified by a predetermined factor to yield an estimation of velocity, and this amount may be integrated to provide a gauge of relative actuator arm position.
Claims17
A method of estimating velocity of an arm of a positioning device, said arm being secured to a motor coil, said method comprising the steps of:
- measuring a first analog voltage across the coil while concurrently holding the arm in a fixed position and generating a first predetermined constant electrical current in the coil to bias movement of the actuator arm in a first direction, said current having a first magnitude and a first direction of flow in the coil;
- and
- storing a signal representative of the measured first analog voltage;
- generating in the coil a second predetermined electrical current having the first magnitude and a second direction of flow opposite the first direction while concurrently measuring a second analog voltage across the coil;
- and
- producing an analog estimated velocity signal representative of the measured second analog voltage minus the stored signal.
Dependencies are inferred from the claim text.