The Key Techniques Of Signal Processing On Circular Grating Reading System

As angle is a vital branch of geometric quantity,angle measurement is an important part of measurement science.With the development of production technology and the growing needs of national economy,angle measurement is widely used in aerospace,mechanical industry,optical industry,aviation and navigation,etc.Many fields require high-precision measurements.Therefore,researching of the key techniques of signal processing on circular grating reading system will be important to improve the accuracy of angle measurement.The permutation intercomparison method is used in traditional angle measurement instruments.A self-calibration angle encoder is researched to make the angle measurement device simpler,smaller.It can realize measuring online and is easy producing.The self-calibration method is made in-depth research in both home and abroad.Up to now,the method in Germany,Japan and Korea are at a high level.We also have a great improvement in self-calibration method in China.Based on the analysis of research status of the self-calibration angle encoder,this paper presents the key techniques of signal processing on circular grating reading system,the main contents of this dissertation are as follows:(1)Angle has a peculiarity that it is a 360° closed system,according to the principle of decile average,equal weights error is added to the multi-reading heads in simulations.Self-calibration algorithm model is established according to the simulation results.The layout of reading heads is designed through the model.The error from the self-calibration and the decile average principle is compared to show the good error consistency of self-calibration angle encoder.(2)According to the self-calibration algorithm model,the arrangement of the reading heads and the construction of air bearing are designed.M1500 S reading head and the circular grating coded disk from Mercury are selected.Then the angle encoder system is installed and commissioned.A calibration system is established based on the self-calibration angle encoder.(3)The graphical programming language LabVIEW is used to design measurement program.It can realize turntable positioning,data acquisition and storage of Autocollimator.A flexible automatic measurement program is built.(4)According to Verification Scheme of Measuring Instrument for Plane Angle,accuracy specifications and traceability technology roadmap of the angle encoder are designed.The angular polygon we need is calibrated according to national verification procedures "JJG 283-2007 Angular Polygon".The autocollimators is calibrated by the national small angle benchmark according to national verification procedures "JJG 202-2007 Autocollimators".The calibrated angular and autocollimator are used to calibrate the self-calibration angle encoder system and test the repeatability and stability of it.So we can evaluate the reliability and measurement uncertainty of the self-calibration system.