Adaptive backstepping control of uncertain nonlinear systems with asymmetry input saturation

In this paper, the adaptive constrained backstepping control method is presented for nonlinear systems suffering from asymmetry actuator saturation and unknown exogenous disturbances. First order command filter is designed to release the constraints effect on the actuators and system states. Fuzzy systems are used to estimate uncertainties on-line. Unlike some existing backstepping control schemes, the developed controller does not require the high order differential of the reference and tedious repeat derivation of virtual control. Furthermore, it handles the circumstances where control gain becomes singular due to adaptation without any restrictive assumptions. Simulation results show the good performance of the presented approach.