Performance measurement and experiment for rotational flexural joint with large-stroke

A method to measure the rotational precision of a flexural joint with a large stroke was proposed to solve the problems that the flexural joint has relatively smaller rotational error and its rotational precision is difficult to be measured directly. Firstly, five kinds of criterions to evaluate the rotational precision were proposed and compared. Then, a proper criterion was chose, and an indirect method to measure the center-shift and stiffness of the flexural joint was developed according to the criterion. With the method, a measuring microscope was used to survey the coordinates of two mark points on the flexural joint, by which the rotational angle and the position of the real rotational center could be calculated, and the central shift of rotation and its shift direction also could be obtained. An experimental platform was built based on the method, and an isosceles trapezoidal flexural joint was used to validate the method. Experiments show that the rotational precision and the stiffness of the flexural joint can be measured at the same time in the experiment. The results are compared with the finite element analysis simulation and it indicates that the error of the experimental result is less than 0.006 mm, which satisfies the requirement of precision test for most common flexural joints with large-strokes.