Design of Compliant Pivots Based on Three-Flexure Arrangement

Abstract Cross-axis pivots, thanks to their high precision and large range of motion, are widely used in mechanical systems. However, their axis drift is generally not negligible and reduces the joint accuracy, limiting the range of the possible implementations. In Literature, this issue has been addressed by following different approaches, often based on the optimization of various kinetostatic parameters or on the combination of more than two flexible elements. In this paper, a novel family of compliant joints is presented. The novel layout is based on the arrangement of three flexures. More specifically, the design of the triple-axis pivots consists of the combination of two crossed flexures with initial curvature and of an auxiliary straight beam. The design procedure includes a proper positioning of the flexures’ centroids and the definition of an equivalence criterion for the rotational stiffness. Non-linear finite element analysis simulations have been performed to evaluate the kinetostatic response of the joint. The results are collected in the form design maps representing the effects of the design parameters on accuracy and stiffness characteristics. An application of the design procedure is presented, and the performance of the defined triple-cross axis pivot are compared to the ones referring to a traditional double-axis joint.