This paper proposes a continuous nonsingular terminal sliding mode (NTSM) control approach for nonlinear systems subject to mismatched terms in order to achieve finite time exact tracking and disturbance rejection. The controller is constructed using a composite method that utilizes a power integrator and combines the output regulation theory, disturbance observation technique, feedback domination and sliding mode control technique. The performance analysis demonstrates that the proposed continuous NTSM controller can drive the system output to the desired reference signal in a finite time in the presence of mismatched time-varying disturbances and nonsmoothed nonlinearities in each channel. The finite time Lyapunov theory is utilized to ensure finite-time convergence of the closed-loop system. The simulation results validate the effectiveness of the proposed continuous NTSM controller.
This paper proposes an invariant manifold based output-feedback sliding mode control (SMC) strategy for systems with mismatched disturbances to achieve asymptotic tracking and disturbance rejection. Different from the existing outputfeedback SMC methods, the invariant manifold is employed to transform the multiple mismatched disturbances into matched ones, which can provide full system dynamics for controller design to improve accuracy. An observer is developed to estimate unmeasurable states, then an output-feedback sliding mode controller is proposed. Moreover, the switching gain of the controller adaptively changes with the estimation error, which reduces chattering in SMC. Experiments on a converter-driven DC motor system verify the superiority of the proposed method.
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