Design and Control of a Lever-Bridge Differential Displacement Reducer With Sub-Nanometer Resolution

Piezoelectric actuators and giant magnetostrictive actuators are widely used in micropositioning and micromanipulation devices. To achieve sub-nanometer resolution with these actuators, a compact flexure-based displacement reducer, which shows the capability of obtaining a very large reduction ratio so as to achieve motion resolution of sub-nanometer, is proposed. It incorporates both bridge-type and lever-type mechanisms, arranged such that the reducer’s output equals the differential displacement between the two mechanisms. Additionally, a kinetostatic model for the reducer is developed. The parameters of the reducer are optimized to minimize the variation of the reduction ratio. The optimization results are validated by those of a finite element model, proving the effectiveness and correctness of the proposed reducer and the kinetostatic model. A prototype is fabricated and valuated by open-loop control and closed-loop control. The average reduction ratio can reach 206.4. By adopting a neural network-based H $\infty $ robust controller, the reducer achieves satisfactory tracking performance. This comprehensive study affirms the reducer’s potential in enhancing the precision of micropositioning and micromanipulation devices. Note to Practitioners—This paper was motivated by the need for higher resolution in actuators to meet the growing demand for precise motion control in applications such as semiconductor manufacturing and biomedical devices. Currently, most compliant mechanisms focus on improving the motion range of actuators, often at the expense of motion resolution. The innovative design presented in this paper combines bridge-type and lever-type mechanisms to achieve a high reduction ratio, which can enhance the motion resolution of actuators, including piezoelectric and giant magnetostrictive systems. Furthermore, integrating a neural network-based H $\infty $ robust controller significantly improves tracking accuracy in dynamic environments. Practitioners in precision-driven fields can leverage this advanced displacement reducer to enhance system performance and explore new technological advancements, ultimately contributing to increased efficiency and capability in micro/nano manufacturing and related sectors.