Realization of a Heterogeneous Cascaded Stage System and the Associated Motion Coupling Control Based on Loop Transmission Shaping

Abstract

Cascaded positioning stages offer a systematic design approach for achieving larger dynamic range and more degrees of freedom (DOFs). Designs such as 1-DOF coarse-fine stages and 2-DOF cascaded stages can be realized effectively. However, due to the coupling resulting from inertial forces caused by the interaction between sub-stages, the dynamic performances are usually limited, and it is desired to study the interaction between sub-stages and develop controllers to reduce the coupling. Here, a single-axis heterogeneous cascaded stage is designed and realized to serve as the platform for addressing the concerns. This novel stage integrates a rubber bearing positioning stage as the upper, and a compliant metallic positioning stage as the bottom components. Through modeling and dynamic testing, the stage dynamics are established, and controller designs based on loop transmission shaping method are implemented. The motion due to inertial coupling is then studied, and the motion can be effectively suppressed after optimizing the controller design by considering the coupling dynamics and positioning-axis error. In summary, the loop transmission shaping control scheme is successfully developed for controlling the motion and reducing the coupling of this cascaded positioning stage. In the future, the stage can be used as a test platform for developing other control schemes for further enhancing the performance of precision motion stage.