Integrated design for high robust performance with quick time-response: an application to head positioning control of a hard disk

The paper is concerned with properties of mechanical structures for which high robust control performance and quick time-response are achievable. We propose a method of integrated design using two indices of robust performance and gain cross-over frequency (servo bandwidth) based on normalized left coprime factorization. It is shown that the structure, in which all resonant modes are in phase and their mode gains are small values, leads to the better control performance than the current structure. We consider a head positioning control of a hard disk drive system in order to make a justification for the proposed method, and the validity is shown by both simulations and experiments.