A New Decoupling Measurement Method of Five-axis Machine Tools’ Geometric Errors Based on Cross Grid Encoder and DBB

Abstract

In order to obtain all the geometric errors of five-axis CNC machine tool, a measuring strategy with cross grid encoder and double ball-bar (DBB) is proposed. According to the theory of multi-body systems, by using the homogeneous coordinate transformation method the model of geometric errors is established. The cross grid encoder is used to detect the translation geometric errors and the DBB is used to measure the rotation ones. Based on the kinematic chain and the properties of geometric errors, the translation geometric errors are measured before the rotation ones. For each axis, both PIGEs (position-independent errors) and PDGEs (position-dependent errors) are under consideration. Then a complete compensated model can be established.