Method for spindle bearing friction estimation for reliable disk drive startup operation

A method to control start up in a disk drive, the method comprising the steps of:

• measuring a resistance of a coil in a voice coil motor (VCM) of the disk drive;
• determining a temperature of the coil of the VCM based on the measured resistance;
• determining a time out period for the disk drive to be powered down if a spindle motor has not reached a desired operational velocity, wherein the timeout period is increased with a decrease in the determined temperature;
• detecting whether the spindle motor reaches the operational velocity within the time out period;
• providing a startup failure signal to enable power down of the spindle motor when the spindle motor does not reach the desired operational velocity within the time out period;
• and
• setting current levels to apply to coil windings of the spindle motor during startup of the spindle motor, the current levels being set to increase torque applied to the spindle motor during startup to correspond with the decrease in the determined temperature.

A method to control start up in a disk drive, the method comprising the steps of:

• measuring a resistance of a coil in a voice coil motor (VCM) of the disk drive;
• determining a temperature of the coil of the VCM based on the measured resistance;
• determining a time out period for the disk drive to be powered down if a spindle motor has not reached a desired operational velocity, wherein the timeout period is increased with a decrease in the determined temperature;
• detecting whether the spindle motor reaches the operational velocity within the time out period;
• providing a startup failure signal to enable power down of the spindle motor when the spindle motor does not reach the desired operational velocity within the time out period;
• and
• applying a sequence of voltages to coil windings of the spindle motor to generate a torque to cause movement of the spindle motor, wherein the torque generated has an increased value corresponding with the decrease in the determined temperature.