A flexure-based displacement reducer capable of achieving very large reduction ratio

Abstract

To achieve positioning of nanometer or even sub-nanometer resolution from traditional piezoelectric actuators and giant magnetostrictive actuators, a bridge-type differential displacement reducer, which shows the capability of obtaining very large reduction ratio, is proposed. The reducer contains two bridge-type flexure mechanisms connected in a way that the output of the reducer equals the difference of the outputs of the two mechanisms. If the two bridge-type flexure mechanisms are identical, no matter how large the input is, the output will always be 0, indicating an infinite reduction ratio theoretically. Therefore, introducing a slight difference between the two mechanisms can yield a very large reduction ratio. A kinetostatic model for the reducer is developed, base on which a reducer exhibiting a reduction ratio of 100 is designed and prototyped. The results of the kinetostatic model, the finite element model and the experiment agree well with each other, validating the effectiveness of the proposed reducer and the correctness of the kinetostatic model.