Disturbance attenuation by output feedback for a class of nonlinear systems with uncertain control coefficient

This paper investigates the problem of disturbance attenuation by output feedback for a class of nonlinear systems with uncertain control coefficient. Due to the existence of uncertain control coefficient and unmeasured states dependent growth, the dynamic high-gain K-filters are introduced for the systems. Based on the K-filters, an appropriate state observer is constructed. Then, the output feedback controller is designed using the backstepping technique, such that disturbance attenuation is achieved in the sense of L_ℒ-gain. An example is given to illustrate the correctness of the theoretical results.