Adaptive Misposition Correcting Method and Apparatus for Magnetic Disk Servo System

This patent describes an adaptive servo control system for magnetic disk storage devices, designed to improve track-following accuracy and increase data track density. The system dynamically corrects for cyclic misposition errors, such as spindle runout, and static errors, such as DC bias forces, by using embedded servo data recorded on the disk. Key features include:

• Dynamic Measurement and Correction: The system measures misposition errors by digitizing servo data, applying a matched digital filter to reject noise and specific harmonic frequencies, and generating a correction signal that compensates for control system and filter lags.
• Iterative Refinement: The misposition correction process is iterated over multiple disk rotations to ensure the system converges to an optimal correction signal.
• Bias Force Correction: It includes an iterative method for measuring and correcting non-linear bias force errors as a function of the radial position of the transducer carriage.
• Individualized Correction: The system stores unique misposition correction signals for each transducer, allowing for precise alignment compensation for each read/write head in multi-head systems.