A robust integral type backstepping controller design for control of uncertain nonlinear systems subject to disturbance

This paper considers the design of a robust controller for a class of nonlinear systems subject to both model uncertainties and unknown external disturbances. Using the concept of both backstepping design and sliding mode control theory, an integral type control algorithm is presented. The proposed controller not only stabilizes nonlinear systems in the presence of mismatched uncertainties, eliminates/reconstructs exogenous disturbances, but also provides smooth control effort. As a result, the developed method is adequate for practical implementation. A criterion of control gains setting for achieving closed-loop stability and disturbance rejection is addressed. Control system design for an unstable nonlinear system is used to illustrate the applicability of the proposed approach and experimental study is also provided to demonstrate the disturbance rejection/reconstruction capability.