Active compensation of flying height in magnetic disk drives

A method of performing an active flying height compensation process for a magnetic disk drive, the method comprising:

• detecting a reduction in flying height of a slider in the magnetic disk drive when the magnetic disk drive is in operation;
• calculating a compensation heating power to apply to at least one heating element in the slider to compensate for the reduction in flying height;
• and
• applying the compensation heating power to the at least one heating element in the slider to alter the air bearing surface and increase the flying height of the slider.

A control system of a magnetic disk drive that is operable to perform active flying height compensation for a slider, the control system comprising:

• a flying height compensation system operable to identify an expected flying height of a slider in the magnetic disk drive, to determine an actual flying height of the slider in operation, and to compare the actual flying height of the slider to the expected flying height to detect a reduction in flying height of the slider;
• the flying height compensation system further operable to calculate a compensation heating power to apply to at least one heating element in the slider to compensate for the reduction in flying height;
• and
• the flying height compensation system further operable to apply the compensation heating power to the at least one heating element in the slider to generate at least one protrusion in the air bearing surface and increase the flying height of the slider.

A magnetic disk drive, comprising:

• a magnetic disk;
• a slider having an air bearing surface that faces a surface of the magnetic disk;
• at least one heating element fabricated in the slider proximate to a sub-ambient pressure pocket on the air bearing surface of the slider;
• a ramp assembly;
• and
• a control system operable to move the slider proximate to the ramp assembly, to apply an unload heating power to the at least one heating element to generate a protrusion substantially in the sub-ambient pressure pocket of the air bearing surface, to detect whether a front edge of the ramp assembly is reached by the slider, to remove the unload heating power if the front edge of the ramp assembly is reached, and to unload the slider from the magnetic disk onto the ramp assembly;
• the control system is further operable to move the slider proximate to the front edge of the ramp assembly, to apply a load heating power to the at least one heating element to generate a protrusion substantially in the sub-ambient pressure pocket of the air bearing surface, to load the slider from the ramp assembly onto the magnetic disk, and to remove the load heating power.