Nonlinearity and Disturbance Compensation Based on Improved Equivalent-Input-Disturbance Approach

This article breaks the limits of applying an equivalent-input-disturbance (EID) approach to nonlinear systems. These limits are caused by the design requirement for the highest angular frequency of disturbances and unknown nonlinearities. We present an improved EID approach that removes this requirement. Thus, its application range is extended and the ability to reject nonlinearities is enhanced. The presented method has many additional merits. It improves the nonlinearity-compensation and disturbance-rejection performances while maintaining the level of configuration complexity and the number of parameters. Furthermore, its system configuration and design are simple. An analysis of the system configuration explains why the nonlinearity-compensation and disturbance-rejection performances are improved. Finally, simulation and experimental results show the validity and superiority of the presented method.