Precision motion control for a dual linear motor-driven gantry system with disturbance estimation via adaptive...

The multi-axis collaborative control of the dual linear motor-driven gantry stage (DLMDGS) has consistently posed significant challenges, particularly in the presence of complex uncertain dynamics and external disturbances, which can degrade control performance and adversely affect final machining accuracy. In order to further improve control accuracy, this paper proposes a high-performance composite adaptive robust control strategy. Specifically, a rigid-flexible coupling model considering the rotational dynamics of the crossbeam is established, and an indirect adaptive method based on recursive least squares (RLS) is developed for the real-time estimation of system model parameters. Additionally, an adaptive sliding mode disturbance observer (ASMDO) is designed to estimate external disturbances within a finite time frame without requiring knowledge of the boundary information regarding the disturbance and its derivative. Meanwhile, a composite controller based on prescribed performance is developed, which has a preassigned maximum overshoot and steady-state error, further enhancing the dynamic and steady-state performance of the system. Finally, the stability of the closed-loop system is demonstrated using Lyapunov's theorem, and comparative experiments are conducted with several commonly studied control strategies. The experimental results demonstrate that the proposed control strategy not only constrains the error overshoot to a certain extent but also achieves a maximum improvement of approximately 70% in the steady-state accuracy of each axis.