A unifying point of view on output feedback designs for global asymptotic stabilization

The design of output feedback for ensuring global asymptotic stability is a difficult task which has attracted the attention of many researchers with very different approaches. We propose a unifying point of view aiming at covering most of these contributions. rt with a necessary condition on the structure of the Lyapunov functions for the closed loop system. This motivates the distinction of two classes of designs: irect approach, also called control error model analysis, in which the attention is focused on directly estimating a stabilizer, and ndirect approach, also called dynamic error model analysis, in which the stabilization task is fulfilled for an estimated model of the system and not directly for the system itself. w how most available results on this topic can be reinterpreted along these lines.