Method and system for simultaneously measuring six degrees of freedom motion errors of a rotary axis based on a semiconductor laser

The rotary axis is the basis of rotational motion. The motion errors of a rotary axis have an extremely important impact on the accuracy of precision machining measuring equipment such as CNC machines, robot manipulators, and laser trackers. It is a difficult problem to realise the fast and precision simultaneous measurement of multi-degree-of-freedom motion errors of a rotary axis. Therefore, a novel method for the simultaneous measurement of six-degree-of-freedom motion errors of a rotary axis by a single-mode fiber coupled semiconductor laser is proposed in this paper. The corresponding system is developed, which has the advantages of high measurement efficiency, simple structure and low cost. A phase-solving method taking the advantages of both the eight-subdivision and the Cordic algorithm is proposed to solve the phase of interference signal, cannot only realize the high-resolution solving of the current signal phase but also quickly obtain high-precision interferometric results. A series of experiments were carried out on the developed system. An experimental system was built and a series of experiments were performed. The experimental results show that the standard deviation of stability for 1 hour of the six-degree-of-freedom measurement is 0.03 µm, 0.02 µm, 0.03 µm, 0.10 , 0.05 and 0.03 , respectively. The repeatability deviation of measuring a rotary axis is ±0.16 µm, ± 0.29 µm, ± 0.25 µm, ± 0.65 , ± 0.62 and ±13.42 , respectively. The maximum deviation of comparison with standard instruments is 0.46 µm, 1.00 µm, 0.49 µm, 1.06 , 1.53 and 0.74 , respectively. It provides a low-cost and high-precision measurement method for simultaneous measurement of six-degree-of-freedom motion errors of rotary axis of precision machining and measuring equipment.