A Composite High-Speed and High-Precision Positioning Approach for Dual-Drive Gantry Stage
Weichao Sun, Jianing Liu, Huijun Gao
Abstract
As an important part of the motion system in high-end manufacturing equipment, dual-drive gantry stage urgently requires higher performance. Planar rapid positioning is a classical application of the gantry stage, while unmodeled dynamics, coupled dynamics of mechanism, and conflict between rapidity and precision bring many difficulties into controller design. In this article, a coupled dynamic model is established and transformed for positioning to provide better guidance for controller design under the rotation mode of the cross beam. A composite positioning control method consisting of a high-speed moving section and a high-precision positioning section is proposed for linearmotors on the gantry to achieve both fast response and precise control simultaneously. In addition, a synchronization scheme is proposed for the dual-driven cross beam with coupled dynamics to enhance the positioning precision of the workbench and balance of the beam. Experiments are conducted on the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$X$</tex-math> </inline-formula> -axis with one linearmotor for the composite positioning method and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Y$</tex-math> </inline-formula> -axis with two linearmotors for the synchronization scheme combined with the composite positioning control separately, through which the effectiveness and validity of the proposed method are verified. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —Planar positioning of dual-drive gantry stage is a significant technical problem in industrial applications, which pursues the ultimate speed and precision performance. In this paper, a dynamic model with rotational mode is established and transformed for positioning in an intuitive way. In addition, a composite positioning method is proposed for linearmotors on the stage to achieve high-speed and high-precision performance in the case of common nonlinear dynamics and disturbances. And then, to achieve high positioning performance of the cross beam while maintaining the balance, a synchronous scheme incorporated with the composite positioning method is presented, based on the transformed model. In industrial scenarios, the proposed method is very practical since a precise, rapid and stable point-to-point planar motion can be obtained only with conventional dynamic models and parameters, and it is crucial for production efficiency and quality.