Linear Integral Control for Nonlinear Systems Subject to Time-Varying Perturbations with Unknown Magnitudes
This thesis focuses on the problem of linear integral control for uncertain nonlinear systems subject to time-varying perturbations with unknown magnitudes by means of backstepping method. The time-varying perturbations can include constant step disturbances, exogenous time-varying disturbances with unknown magnitudes, and modeling uncertainties with unknown system parameters. Firstly, a new linear integral controller consisting of integral dynamic is constructed to drive the states of uncertain systems without nonlinear terms to the origin asymptotically. Secondly, by introducing high-gain technique, a new linear integral controller is then constructed to drive the states of uncertain systems to the origin asymptotically. Finally, based on a proposed new stability criterion, we further extend our main results to study a class of uncertain nonlinear systems with a more general time-varying perturbations with unknown magnitudes.