Continuous higher order sliding mode observers for a class of uncertain nonlinear systems

Two nonlinear state observers are proposed to reconstruct the system states for a class of uncertain nonlinear systems. Both state observers are designed based on continuous higher order sliding mode and terminal sliding mode concepts. The proposed observers are chattering-free and constructed without any detailed model knowledge of the system. Desirable features of the proposed observers include that they are immune to noise and can be designed separately from a controller. Lyapunov stability theory is employed to prove the finite-time convergent and uniformly ultimately bounded observation. Simulation results are provided to demonstrate the effectiveness and improved performance of the developed observers.