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-offreedom 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 & mu;m, 0.02 & mu;m, 0.03 & mu;m, 0.10 & DPRIME;, 0.05 & DPRIME;and 0.03 & DPRIME;, respectively. The repeatability deviation of measuring a rotary axis is & PLUSMN;0.16 & mu;m, & PLUSMN; 0.29 & mu;m, & PLUSMN; 0.25 & mu;m, & PLUSMN; 0.65 & DPRIME;, & PLUSMN; 0.62 & DPRIME;and & PLUSMN;13.42 & DPRIME;, respectively. The maximum deviation of comparison with standard instruments is 0.46 & mu;m, 1.00 & mu;m, 0.49 & mu;m, 1.06 & DPRIME;, 1.53 & DPRIME;and 0.74 & DPRIME;, 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.