A Modified Sequential Multilateration Scheme and its Application in Geometric Error Measurement of Rotary Axis

Geometric error compensation becomes an essential technology for improving the accuracy of multi-axes machine tools. Laser tracker has been has been considered as an enabling instrument which can be used to measure the geometric error of machine tools due to its high accurate and feasible measurement capability. This paper presents a modified sequential multilateration method for measuring the geometric errors of rotary axes of the machine tools. The method is developed based on a single laser tracker and three targets fixing on the rotary stage. The coordinates of the three targets are measured based on the modified sequential multilateration method using a single laser tracker when the rotary stage is rotated. Then geometric error components are identified based on established geometric error model which takes the positioning error of the targets as input. The validity of the proposed method is verified through both computer simulation and experiments conducted on a multi-axis machine tool.