On the Development of Terminal Sliding Mode Observers

In this paper, a Terminal Sliding Mode Observer (TSMO) for systems with general state-space representation is proposed. The effect of uncertainties and disturbances are incorporated in the system. In the proposed method, a transformation is employed to separate the states into those participate in measurements and those which do not. Compared to conventional sliding mode observers, which enable finite time convergence of output errors and asymptotic convergence of non-output errors, the proposed TSMO guarantees finite time convergence of all measured and unmeasured states' estimation errors. Three appropriate Lyapunov functions are defined for robust and finite time convergence of all estimation errors. Finally, to highlight the effectiveness of the methodology, the developed TSMO is applied to a well-known six-degree of freedom wind turbine model. The results confirm that the proposed TSMO faithfully estimates all the states fast and accurately.