Unknown disturbance input estimation for the nonlinear Lipschitz uncertain systems

In this paper, we consider problem of state as well as unknown disturbance input estimation for the nonlinear Lipschitz uncertain systems. A new design concept of the Lipschitz UIO is presented, which can simultaneously estimate the system states and unknown disturbance inputs, and the conditions for the existence of the robust compound observer are established. Combined with LMI methods, the designing freedoms are released, and LMI existence conditions and some verification are given for the Lipschitz UIO which can asymptotically estimate the unknown disturbance inputs. Numerical simulation results are presented to validate the approach and the robustness to the system nonlinearity and uncertainty.