Research On Digital Subdivision Of Grating Moiré Signal Based On Anti-tangent Method

Grating measurement technology occupies an important position in the field of precision measurement.Compared with laser measurement,grating is often affected by the environment less and has strong anti-interference ability.Meanwhile,it has remarkable advantages such as high precision,high resolution and fast response.With the booming development of China's manufacturing industry,the demand for Angle measurement is more and more urgent.Although China has made great progress in the application of grating system in recent years,it still lags behind developed countries such as Germany and Japan.The subdivision accuracy of grating moiré signals is limited by the quality of photoelectric signals.Foreign companies have developed corresponding products for this problem,but high-end grating encoders are banned and blocked in China.In order to meet the demand of grating Angle measurement,a high resolution and high precision real-time subdivision system is urgently needed.According to the current situation of domestic and foreign subdivision schemes and the demand of high resolution and high precision of the subject,this paper conducts research on the application of signal compensation and subdivision technology.The main contents include:(1)According to the anti-tangent principle,the numerical subdivision scheme is given,the influence of grating moiré signal quality on subdivision precision is analyzed,and the mathematical quantization model is established,which provides theoretical basis for improving subdivision precision.(2)According to moiré signal's equal-amplitude and orthogonality compensation principle,the CORDIC(Coordinate Rotation Digital Computer)algorithm is studied,and the compensation accuracy of moire signal's orthogonality deviation is further improved by optimizing the calculation process of arcsine function.(3)High speed ADC sampling circuit was designed to obtain moire signal,and a1024 times subdivision digital circuit algorithm was developed based on FPGA(Field Programmable Gate Array)platform,which improved the accuracy and reliability of Angle measurement by optimizing the algorithm structure.(4)The effectiveness of the proposed subdivision system is proved by algorithm simulation,signal source simulation and Angle measurement.The subdivision error calibration platform is built and compared with the commercial products of Micro E company.The experimental results show that the subdivision system designed in this paper achieves higher angular measurement accuracy.