Active Disturbance Rejection Control

In this discussion, we focus on second-order nonlinear active disturbance rejection controllers. This controller represents an advanced control algorithm that delivers superior control performance when handling complex nonlinear systems. Its core mechanism involves integrating an adaptive disturbance observer within the controller structure to measure and compensate for system disturbances in real-time. This control strategy has been widely implemented across various domains including robotics, aerospace control, and power system regulation. From an implementation perspective, the algorithm typically employs an extended state observer (ESO) to estimate combined internal dynamics and external disturbances, followed by a nonlinear feedback law for compensation. The control output calculation often involves tracking differentiator components for derivative estimation and nonlinear state error feedback for robust performance. Through further optimization and refinement of this algorithm—such as parameter tuning using genetic algorithms or incorporating adaptive gain scheduling—we can enhance its practical application effectiveness in real-world scenarios.