In this paper we show by examples that optimum and robust controllers, designed by using the H2, H, l1and formulations, can produce extremely fragile controllers, in the sense that vanishingly small perturbations of the coefficients of the designed controller destabilize the closed loop control system. The examples show that this fragility also usually manifests itself as extremely poor gain and phase margins of the closed loop system.
name of conference
Proceedings of the 1997 American Control Conference (Cat. No.97CH36041)
