Kinematic and geometric error compensation of a coordinate measuring machine

In this paper, kinematic modelling of a Coordinate Measuring Machine (CMM) is carried out and the methodology followed in modelling is explained in de tail. The model is simplified by certain assumptions which may result in ov er-simplification of the model. Consequently, the model is investigated and enhanced by adding the relevant and suitable geometric error terms. Differ ent approaches are employed to evaluate the model coefficients, In the firs t approach, a commercial ring gauge is measured in a structured lattice in the work volume of the CMM. Resulting errors in these measurements are used in conjunction with some statistical methods to arrive at sets of model co efficients values. The second approach is based on measurement of the indiv idual 21 error terms in the CMM by means of laser interferometry. These mea surements are used to evaluate another set of model coefficients, A compens ation strategy is proposed and tested using the model and the sets of coeff icients obtained, Volumetric Performance of the CMM is evaluated according to ASME standards, before and after compensation. Improvement in the CMM vo lumetric performance is demonstrated and compared. (C) 2000 Elsevier Scienc e Ltd. All rights reserved.