An On-Line Measurement Technique for Machine Volumetric Error Compensation

A hybrid on-line and off-line measurement technique is developed for machine volumetric error compensation based on a multiple-degree-of-freedom laser optical system. When implemented on a 3-axis machine up to 15 geometric error components can be measured simultaneously on-line and the remaining 6 components need to be calibrated off-line. Since the on-line measurement systems use different metrology bases, a modified volumetric error model is derived for a milling machine by considering the measurement features of the multiple-degree-of-freedom system. Through experimental tests, it was found that the discrepancy between the identified errors and the actual errors was less than 4 μm out of a maximum range of 20 μm.