Method and apparatus reducing off track head motion due to disk vibration in a hard disk drive using configuration of the disk drive servo controller

A method of controlling a voice coil in a hard disk drive, comprising the steps of:

• reducing a gain of a PES within a disk vibration frequency range;
• wherein said disk vibration frequency range includes frequencies between at least 1000 Herz and at most 3000 Herz;
• and
• increasing said gain of said PES within a lower frequency range;
• wherein said lower frequency range includes frequencies between at least 20 Herz and at most 800 Herz;
• said head gimbal assembly responding to mechanical vibrations in said rotating disk surface by providing said read-write head with radial motion toward said track, further comprising the steps of:
• moving said slider parallel to said disk surface toward said track, when said disk surface is flat, by an actuator arm moving said slider by a lever action through a principal axis with said slider aligned at a bias angle, further comprising one of the steps of:
• said actuator arm moving, through a flexure, said slider mounted to said flexure at a second bias angle to said principal axis;
• and
• moving said actuator arm by a level action through a principal axis with said slider parallel said disk surface and flexibly mounted by said flexure at said second bias angle to said actuator arm;
• and
• radially moving said slider toward said track when said disk surface is bent, by said lever action through said principal axis at said bias angle causing said slider to move radially toward said track, when said disk surface is bent, further comprising one of the steps of:
• said flexure responding as said disk surface is bent, through said second bias angle, causing said slider to move radially toward said track;
• and
• said flexure responding as said disk surface is bent through said second bias angle causing said slider to radially move toward said track;
• wherein said voice coil drives an actuator arm positioning said head gimbal assembly for a read-write head communicatively accessing a track on a said rotating disk surface to generate said PES;
• and
• wherein said PES is a function of said head gimbal assembly responding to mechanical vibrations in said rotating disk surface by providing said read-write head with radial motion toward said track.