Improved segmental active disturbance rejection control for direct-drive valve controlled hydraulic shaking table

To address the performance degradation of hydraulic shaking table under nonlinear disturbances, an improved segmental active disturbance rejection controller (IS-ADRC) based on a switching control law is designed. A self-coupling PID (SC-PID) control law is designed, and an adaptive speed factor model is proposed to enhance the system’s response speed without compromising disturbance observation ability, thus avoiding oscillations and instability caused by high-gain observer. To overcome the jitter issue in traditional nonlinear state error feedback (NLSEF) control laws, an improved control law (INLSEF) based on a smooth Fal-M function is designed to replace the traditional fal function. Moreover, considering the potential for integral saturation, a switching principle is designed to switch from the SC-PID control law to the INLSEF control law at small errors, ensuring smooth system convergence. The stability of the controller is proved using Lyapunov stability theory. Results demonstrate that the proposed IS-ADRC improves the response speed and anti-disturbance ability of the hydraulic shaking table. Furthermore, the Fal-M function effectively reduces the jitter phenomenon compared to traditional ADRC.