Robust integral control for a class of uncertain nonlinear systems

For a class of systems with uncertain nonlinearities, the authors design robust integral controllers which achieve the tracking of constant reference signals. No parameterizations of the uncertain functions are needed, and robustness with respect to exogenous disturbances is guaranteed. High gain is needed only for disturbance rejection; in the absence of disturbances, convergence of the tracking error to zero is achieved without high gain. These integral controllers are generally of lower order than adaptive controllers would be were parameterizations of the uncertainties available