Underactuated System Control Based on Improved Active Disturbance Rejection Control

To achieve the control effect of high precision, fast response speed, and good stability for a class of underactuated systems, a control strategy based on the improved active disturbance rejection controller is designed. First, a new sliding mode tracking differentiator is designed on the basis of a new sliding mode reaching rate. Given that traditional active disturbance rejection control is only suitable for single-input and single-output systems, two sliding mode tracking differentiators are used in the proposed model to obtain the given displacement and velocity as well as the actual displacement and velocity, respectively. Then, a new nonlinear function with enhanced smoothness and convergence is designed. Using the nonlinear function, an improved extended state observer for the underactuated system is designed to optimize its following error ability. Given that the parameter values of the control rate part are difficult to adjust, the particle swarm optimization algorithm is used to optimize the four parameter values of the control rate part. Finally, the simulation results show that the proposed control strategy can realize a fast and stable control of such underactuated systems.