Optimal H∞ output feedback control for a class of nonlinear systems

This paper discusses optimal H_∞ output feedback control using linear matrix inequalities for a class of systems with sector bounded nonlinearities. A unified model, which is the interconnection of a linear dynamic system and a sector bounded static nonlinear operator, is proposed to describe these systems. Based on the H_∞ performance analysis of the closed-loop systems including the unified model and output feedback controller, the parameters of output controller are determined not only to guarantee global asymptotic stability of the closed-loop system without disturbances, but also to reduce the effect of external disturbance on the performance output to a minimal H_∞ norm constraint. The nonlinear systems satisfying certain sector type constraints can be transformed into this unified model, and H_∞ output feedback controllers are designed for these systems in a unified way.