Output Feedback Uncertain Nonlinear Systems Disturbance Rejection

For nonlinear systems, which control problem has been the focus of research scholars. Inthis paper, using the backstepping technique, we research the disturbance attenuation problem byoutput feedback for two classes of uncertain nonlinear systems. We introduce the research statusand research significance of the nonlinear systems control problem. Then, we reverse its research.Finally, we study the following two questions:1. Disturbance attenuation by output feedback for a class of uncertain nonlinearsystemsThis part mainly for a class of nonlinear systems containing uncertain control coefficient,studies its disturbance attenuation problem. Apart from other existing literatures, this part of thesystem with unknown coefficients, there exists the nonlinear term which depends on systemoutput. The characteristics make the system more general than other nonlinear systems, and havemore research value. The system output is the sole state that we know. It forces us to not be ableto solve the problem using state feedback. Therefore, we use output feedback to achieve our goal.At last, we show the method is scientific and giving verified through simulation.2. Disturbance attenuation by output feedback for a class of uncertain nonlinearsystems with unknown control directionsIn this part, we study the problem of disturbance attenuation for a class of nonlinear systemswith output feedback. Unlike other literatures, the systems studied here have unknowncoefficients symbolic, which will make us to face to more difficulties and challenges. Based onNussbaum-type gain technology, we successfully address the problem. This part requires onlythe output is known. Similar to the first system, based on the new system we design controllerand estimator. At last, we show that the method is scientific and giving verified throughsimulation.