High-Performance Control Method for Six-Degree-of-Freedom Micromotion Stage Based on High-Order Sliding Mode Control Theory

In this article, a high-performance control method based on high-order sliding mode control theory is proposed to improve the trajectory tracking performance of the six-degree-of-freedom micromotion stage (MMS) and suppress the crosstalk between different degrees of freedom. The internal coupling mechanism of MMS is analyzed to implement a static decoupling control design, upon which the position loop controller is designed: A high-order sliding mode observer is proposed for estimating velocity states and compensating for concentrated disturbances, enabling dynamic decoupling compensation to be achieved. An adaptive super-twisting algorithm is proposed for reaching law design to effectively mitigate the chattering phenomenon and dynamically enhance the approach rate. A nonsingular fast terminal sliding mode surface is proposed to ensure finite-time convergence of the system states, while avoiding singularities in the control law. Finally, the proposed control method is evaluated against proportional-integral-differential control, integral sliding mode control, and super-twisting sliding mode control, through trajectory tracking and load testing experiments to demonstrate its feasibility and effectiveness. The results illustrate that the proposed controller exhibits rapid dynamic response without overshoot, minimal chattering, and demonstrates superior robustness against model uncertainties and external disturbances.