Design and Development of a Two Degree-of-Freedom Rotational Flexure Mechanism for Precise Unbalance Measurements

Abstract

To measure unbalanced moments, the knife-edge is used as a support module in traditional platforms, but performances rapidly deteriorate as the edge is worn down. In this paper, considering the requirements of measurements, a two degree-of-freedom (DOF) flexure mechanism is, thus, presented to overcome this drawback. First, off-axis stiffness and manufacturability are improved qualitatively by means of configuration analysis. Then, four generalized cross-spring pivots are exploited in the 2DOF flexure mechanism, and the geometric parameters are analyzed to achieve approximately constant rotational stiffness and reduced center shift simultaneously, which benefits calibration procedure and measurement precision. Models are further developed to determine the shape parameters of leaf-springs and transducer performances. Therefore, a low rotational stiffness is obtained to ensure a high resolution for measurements, and a high load-carrying capacity is achieved via strength checking. Finally, finite element analysis (FEA) is carried out to validate the proposed design, and experimental results demonstrate that the developed platform is capable of unbalance measurements with a high precision and resolution.