A simple global asymptotic convergent observer for uncertain mechanical systems

A simple nonlinear observer is proposed for a class of uncertain nonlinear multiple-input–multiple-output mechanical systems whose dynamics are first-order differentiable. The proposed observer is constructed without any detailed model knowledge of the system and the observer gains are easily chosen. Another interesting features of the proposed observer include that it is more immune to noise and is high robust against parameters variations, and thus it is readily implemented. Lyapunov's direct method is employed to prove global asymptotic convergent observation. Extensive simulations are presented to illustrate the effectiveness and improved performance of the proposed observer.