Three-face step-diagonal measurement method for the estimation of volumetric positioning errors in a 3D workspace

In this paper, it is demonstrated that volumetric positioning errors can be calculated by measuring the displacements of three face step-diagonals and three additional linear positions. The three-face step-diagonal tests are used in combination with three directly measured linear errors to estimate nine errors in a three-dimensional workspace, including six straightness motion errors and three perpendicular errors. These errors in the workspace were also directly measured to evaluate the estimated errors. The maximum difference between estimated and measured errors was 0.45μm for the straightness errors, 2.8μrad for the perpendicular errors. Moreover, in practice, the three-face step-diagonal method is easier and faster than direct measurement along each axis and more convenient than the conventional step-diagonal technique. Hence, this method is suitable for industrial applications. ► 12 errors (3 linear motion, 6 straightness motion, 3 perpendicular) were studied. ► Errors are estimated by the data of 3 face step-diagonal and 3 linear measurements. ► Direct measurement tests were used to assess the accuracy of the estimates.