Technique to compensate for resonances and disturbances on primary actuator through use of a secondary actuator

摘要

A control system for an actuator arm assembly of a hard disk drive reduces the Non-Repeatable Run-out (NRRO) caused from external sources exciting higher-frequency actuator arm assembly modes. The actuator arm assembly includes a primary actuator and a secondary actuator. The control system includes a primary control loop controlling the primary actuator and a secondary control loop controlling the secondary actuator. The secondary control loop includes at least one peak filter at a frequency corresponding to at least one frequency that is greater in frequency than the primary mode of the actuator arm assembly. The primary actuator can be any type of primary actuator. Similarly, the secondary actuator can be any type of actuator that is located between the primary actuator and a read/write head.