Adaptive Backstepping Controller Based on Structural Self-Regulating NESO for Position Control of Valve Positioner Systems

As the central intelligent industrial instrument in process industry automation, the valve positioner system (VPS) regulates flow, pressure, and temperature precisely, ensuring production process accuracy, stability, and reliability. However, the VPS exhibits time-varying nonlinearity, parameter uncertainty, and dead-zone characteristics, and is also subjected to external disturbances. Existing control algorithms have the dual limitations of poor robustness and insufficient tracking accuracy, and it is challenging to solve the contradiction between initial response speed and overshoot effectively. To address these challenges, we propose an adaptive backstepping controller based on a structural self-regulating nonlinear extended state observer (NESO). First, the VPS’s dynamic model is established, in which uncertain parameters are estimated using adaptive laws. Then, a structural self-regulating NESO is designed, which automatically adjusts its structural parameters according to the changes in the system and realizes the accurate estimation of the perturbation and system state. Next, the control strategy is designed using adaptive laws based on the backstepping technique, further enhanced by incorporating a nonlinear control quantity into the virtual control law. The stability and robustness of the system can be improved while ensuring high precision control. Finally, the effectiveness of the proposed algorithm was evaluated through comparative experiments under consistent conditions. The proposed controller achieved a steady-state tracking error of 0.5%, compared to 1.5% for the adaptive integral sliding mode controller, with both exhibiting similar response times of approximately 2.6 s. In terms of overshoot, the proposed controller produced a peak value of 0.14 mm, compared to 0.18 mm observed with the active disturbance rejection controller. These results indicate enhanced tracking accuracy and improved transient performance. Thus, the proposed algorithm delivers precise, stable, and rapid valve position control with excellent robustness and disturbance-rejection capabilities.