The Research And Design Of Space-Applied High-Precision Photoelectric Rotary Encoder

With the great progress of photo-etch pattern on stainless steel code disk, the technology of plate-making based on steel code disk is continually maturing. Compared to glass grating disk, metal grating disk is more anti-seismic and more adaptive under fluctuant temperature. The latest development of rotary optical encoder has been analyzed. Considered the priority of metal grating encoder, steel code disk was selected as the core part of rotary optical encoder. The experiment system of absolute rotary optical encoder which is simple in structure, more reliable, more practicable and more adaptive in space application, has been designed. The system is an important valuable reference to the space application research of high precision shaft angle measurement.The main research lies in:(1)Angle measurement principle with Moire fringe signals based on reflective grating interference system has been analyzed. Basic structure of the system design of rotary optical encoder is determined.(2)High rotary accuracy set of axes under fluctuant temperature has been designed. It highly ensured that high-quality grating photoelectric signals can be extracted.(3)To settle the problems in space application, such as, the needs of miniaturization and the anti-seismic, matrix encoding way has been applied to reflective grating disk of metal, so the size of encoder disk is been greatly reduced. Lots of measures are taken, succeeding to pioneers'way of the optimizing of grating photoelectric signal, such as multi-line averaging, Split Phase Indicative Gratings, signal subtraction processing, multi-reading photo-head addition and averaging, etc. Extracting high quality grating photoelectric signals have been come true.(4)Based on fundamental research of solid-state physics, influence on photoelectric sensor of shaft angle measurement bench, and degradation mechanism of photo-electronic device has been analyzed in the space environment. A self-adaptive signal processing Technique has been taken to avoiding error code output, because of fluctuant temperature in out space. So operational life span of photoelectric encoder can be greatly prolonged.(5)The source of shaft angle measurement has been refined. 21-bit high-precision code can be output continuously and stably under fluctuant temperature surrounding. The precision of Absolute Type Encoder was been calibration, and the systematic error was also been amended.The originality innovation lies in the application of miniaturized code track design on reflective metal disk, and the system resolution aiming at the problem of fluctuant temperature and radiation in out space. Index of the system shaft angle measurement: Resolution is 0.618″; Precision is±3″; Temperature fluctuant is -40℃～80℃; The system can work in order when space radiation is not less than 200 Gry.