Coupled disturbance reconstruction by sliding mode observer approach for nonlinear system

This paper concentrates on the estimation of system states and the reconstruction of disturbances in a class of nonlinear systems considering stateless situation. The disturbances are coupled with time-varying parameters. The sliding mode observer approach is utilized to solve these two issues. Firstly, a descriptor model is presented by transforming the coupled disturbances into the decoupled form. Secondly, the sliding mode observer is designed to estimate the decoupled disturbances and system states of nonlinear systems. The coupled disturbance can be reconstructed hereafter. The detailed methods of designing the observer, together with the sufficient condition to guarantee the existence of the observer are also given. Finally, a simulation and a robot manipulator experiment are provided to examine the validity of the proposed design approach.