H2 guaranteed cost control in track-following servos

Abstract

This chapter presents two newcontrol synthesis approaches for dual-stage track-following servo systems. Both approaches are based on script H sign 2 guaranteed cost analysis, in which an upper bound on the worst-case script H sign2 performance of a discretetime system with gain-bounded unstructured causal LTI uncertainty is determined by solving either a semi-definite program (SDP) or several Riccati equations. We review the results of a paper on script H sign2 guaranteed cost analysis and a paper on optimal full information script H sign2 guaranteed cost control and then use these results to develop two output feedback control synthesis approaches. The first approach is based entirely on the solution of SDPs whereas the second approach exploits Riccati equation structure to reduce the number and complexity of the SDPs that need to be solved. Throughout the paper, we apply the analysis and control techniques to a hard disk drive model with a PZT-actuated suspension and demonstrate that the approaches that exploit Riccati equation structure are faster and at least as accurate as their SDP counterparts. © 2011 Springer-Verlag Berlin Heidelberg.