Velocity Sliding Mode Control for Seam Tracking Based on Extended State Observer

To address the problems of slow response, low accuracy, and weak disturbance rejection in the weld seam centering control system prior to steel pipemechanical expansion processing, this study proposed a sliding mode control(SMC) strategy with secondary compensation based on an extended state observer (ESO). First, an ESO was designed to perform lumped observation and real-time estimation of the inherent nonlinear friction and high-frequency periodic load disturbances in the system. Subsequently, a dual-loop sliding mode speed controller based on the ESO was designed to achieve disturbance suppression and speed tracking. The stability of the closed-loop system was proven using Lyapunov stability theory. Experimental results showed that, compared with traditional methods, the proposed strategy significantly suppressed various disturbances and exhibited faster response speed, higher tracking accuracy, and stronger robustness in weld seam centering control.