Observers with Discrete-Time Measurements in the Sliding Mode Output-Feedback Stabilization of Nonlinear Systems

The chapter investigates the problem of designing an observer for nonlinear nonaffine systems with discrete-time measurements (continuous-discrete-time systems). The chapter considers the variable-structure control of nonlinear systems when the state vector is not completely available and the output measurements are discrete-time; the use of suitably designed observers is required. The strategy of introducing integrators in the input channel is exploited to enlarge the class of tractable control systems. An observer is proposed and conditions are found under which the convergence to the unique ideal solution is proven for both system and observer. The control problem is solved by forcing a sliding regime for the observer, while satisfying an exponential stability criterion for the observation error state equation.