Handling of nonlinear systems using filtered high‐gain output feedback controller

Summary This paper develops a filtered high‐gain output feedback controller for a class of nonlinear systems in the presence of unknown state‐dependent and time‐varying nonlinearities. It considers that the nonlinearities satisfy a semiglobal Lipschitz condition. The presence of high‐gain observer in the adaptive law delivers a good property of disturbance rejection at the cost of peaking phenomenon as well as reduced robustness. The addition of filtering mechanism in the control law overcomes the cons of high‐gain observer and makes it robust to uncertainties in modeling the nonlinear functions. In this way, the filtered high‐gain output feedback controller realizes nonlinear time‐varying uncertainty cancelation and good tracking delivering with guaranteed robustness. The simulation results demonstrate the high efficiency of our novel design for handling of a class of nonlinear systems in the presence of time‐varying uncertainty when compared with saturated control signal.