The self-calibration method based on grating-rulers used for 6-DOF motion measurement system

This study investigates an approach to realize the self-calibration of six-degree-of-freedom motion measurement system with simple steps in a short period. A mathematical model based on the closed-loop vector is used to implement the self-calibration. It only requires a linkage structure and grating rules to read motion information. Compared with the traditional calibration methods, the investigated method has advantages on flexibility and time-saving. The feasibility of it is experimentally validated on the Stewart platform, and the accuracy is compared to the external laser tracker-based calibration method. The experimental analyses show that the investigated method has a good effect on the parameter identification of the measurement system. Moreover, the physical constraints are added on the top of the linkage, so that the 6-DOF motion measurement is transformed into the linear motion measurement. It avoids the motion coupling in the measurement information and further enhances the precision of the measurement results.