Fast volumetric error assessment of a gantry-type machine using multi-degree-of-freedom laser-based sensors and Vector Transfer Model

Gantry-type machines are normally large-scaled manufacturing equipment, such as contact/noncontact measuring machines and cutting machines. Its actual positional shift of the functional point (FP) from the ideal position in three directional components within the working volume is called the volumetric error and is mainly caused by geometric errors of each axis. Currently, the most popular volumetric error model with homogeneous transformation matrix (HTM) method is based on linkage-chain kinematics, which is lack of measurement principles in practice. Besides, most commercial instruments can only provide one-by-one geometric error measurement, which is too time consuming. In this paper, a new volumetric error modeling method developed by the author’s group, called the vector transfer (VT) method based on the Abbe principle and Bryan principle, was applied to a moving gantry-type optical measuring machine (OMM). The geometric errors in each axis were simultaneously measured by the developed multi-degree-of-freedom measuring systems (MDFMs) to reduce the measurement time and uncertainty. The volumetric errors of tested OMM were accurately assessed by experimental verification to the accuracy of 93%, which proved the effectiveness and applicability of the VT method.