Data-Driven Loop-Shaping with Resonant Filters Integrating Unstable and Stable Poles in Dual-Stage Actuator Hard Disk Drives

Increasing demands for data storage capacity have grown the necessity for advanced loop-shaping techniques in Hard Disk Drives (HDD). The aim of this paper is to develop a loop-shaping method using resonant filters integrating unstable and stable poles for a dual-stage actuator HDD. The phase stability condition based on the Nyquist stability criterion is unifed in the resonant filters with unstable and stable poles for frequency response data-driven loop-shaping. The resonant filters are designed by iterative convex optimization integrating resonant filters with unstable and stable poles at the same resonance frequency. The optimized vector locus enables more flexible loop-shaping with elliptical orbits integrating unstable and stable resonant modes. The track-following performance improvement with the developed approach is validated in a dual-stage actuator HDD benchmark problem.