The robust integral control problem is studied for a class of nonlinear systems with input-to-state stable （ISS） unmodeled dynamics in this paper. It does not require a priori knowledge of the control coefficients. Combining the Nussbaum-type gain technique and the backstepping design, we propose a state feedback controller, which could achieve the global asymptotic tracking for any constant reference signal, irrespective of the unmeasured dynamic disturbance. It is shown that the proposed methodology further extends the existing robust nonlinear integral control results. Simulation results verify the correctness of the theoretical analysis.
This paper studies the problem of output feedback stabilization for a class of more general nonholonomic systems whose nonlinear drifts are polynomially bounded by high-order terms of unmeasured states. An output feedback controller is obtained applying the backstepping approach and the dual observer method. The homogenous theory is also utilized in the recursive process. Together with a switching control scheme, the designed controller guarantees that the closed-loop system is output feedback globally asymptotically stabilized and the states converge to zero asymptotically. A simulation example is provided to illustrate the validness of the proposed approach.
