Run-out oriented controller design for nanoscale servo systems of hard disk drives

This article proposes a controller optimization for given external inputs, i.e., fluttering NRRO, RRO, sensor noise, and torque disturbance to be called “run-outs.” This run-out oriented controller design is based on a response surface method and provides an optimal controller that minimizes positioning error (PE) due to these run-outs. The proposed method is not only for controller tuning but also gives us a clue to seek a direction about which disturbance we should prioritize to be reduced from a viewpoint of system integration.