Nonlinear Sliding Mode State and Unknown Input Estimations

This book presents a new perspective to the design and analysis sliding mode observers (SMO) and unknown input estimations of uncertain nonlinear continuous and discrete-time systems. The key idea is to exploit the observability of the unknown inputs from the measured outputs. For several general classes of nonlinear systems perturbed by unknown inputs, SMO¿s are incorporated into the nonlinear observer designs. The sliding surfaces are designed from the measurable output estimation errors and hence can be readily implemented. In the sliding mode, the unknown inputs can be estimated from the equivalent control. The inherent problem associated with discrete-time sliding mode observers is solved by re-defining the existence of discrete-time sliding mode with a new strategy that completely eliminates chattering. The methods presented in the book are useful for efficient monitoring and control of nonlinear systems in the presence of unknown dynamics or disturbances. The methods have potential applications in fault detection and identification (FDI).