Disk drive with a dual-stage actuator and failure detection and recovery system for the secondary actuator

摘要

A dual-stage actuator disk drive has calibration tracks located in a nondata band, and uses a secondary-actuator failure detection and calibration test run by the servo control processor. The calibration tracks contain a pattern of pre-written magnetized test blocks. The test is run with the primary actuator biased against a crash stop, which enables the read head to access the calibration tracks. The servo control processor generates a test signal to the secondary actuator and receives a calibration signal from the read head as the read head detects the test blocks in the calibration tracks. The test comprises two measurements: a measurement of the secondary actuator static characteristics, and a measurement of the secondary actuator dynamic characteristics.