Patent ID: 8724254

Claim:
A method of evaluating a dual stage actuator (DSA) servo loop in a disk drive, the disk drive comprising a head, a disk surface, and a dual stage actuator (DSA) servo loop comprising a voice coil motor (VCM) servo loop and a microactuator servo loop operable to actuate the head over the disk surface, the method comprising: adding a first sinusoidal signal A 1 to a VCM control signal B 1 generated by the VCM servo loop; measuring a response of the VCM control signal B 1 to the first sinusoidal signal A 1 ; computing a closed loop response of the VCM servo loop in response to A 1 and B 1 ; adding a second sinusoidal signal A 2 to a microactuator control signal B 2 generated by the microactuator servo loop; measuring a response of the microactuator control signal B 2 to the second sinusoidal signal A 2 ; and computing a closed loop response of the microactuator servo loop in response to A 2 and B 2 .