Nonlinear Time-Varying Controllers for Uniform Stabilization

This paper is devoted to the topic of (robust) uniform stabilizability of families of linear time-invariant (LTI) plants arising from additive and multiplicative descriptions of unstructured uncertainty. Our results extend some previous work reported in [9], and show that there is no advantage in using general nonlinear time-varying (NLTV) controllers over LTI ones for certain problems of (robust) uniform stabilization. Some auxiliary results on L¿-norm approximation theory are also obtained.