In this paper, a new robust adaptive control scheme is proposed for a class of nonlinear systems with external disturbance and output modeling error. The output modeling error considered here is allowed to depend on all systems states. Thus, traditional backstepping techniques cannot be used in the controller design due to such an unknown output modeling error existing in coordinate changes. This problem has been solved by the developed robust adaptive control scheme. By establishing the upper bound function of the unknown output modeling error depending on all the system states, the linear inequality relationship between the state vector and the transformation vector is obtained. This is the key to stability analysis. Input saturation is also considered in the controller design. It is shown that the proposed adaptive control scheme can ensure that all signals in the closed-loop system are bounded. Simulation studies verify the effectiveness of the proposed scheme.
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