Research On Key Technology Of Miniature Single-Track Absolute Rotary Encoder

Photoelectric rotary encoder is photoelectronic digital precision angle measurement device which could real-time transform the angle information into certain numerical code to output. It could be widely used in real-time control and dynamic measurement systems areas of aerospace, automatic control and radar system because of characters such as high resolution, high accuracy, long service life, and easy to maintain. With the rapid development of technology and incessantly broadened application fields, the increasingly higher requirements for volume, quality and good impact resistance of the encoder have push it to develop in the direction of high-precision, miniaturization and impact-resistant. Therefore, miniaturization and impact-resistant has become an urgent problem to be solved.In order to achieve miniaturization and high resolution and to enhance the impact-resistant performance of encoders, research on key technology of a novel miniature single-track absolute rotary is developed in this paper. It laid a foundation for the research on absolute metal rotary encoder.On the basis of loads of references, the formation mechanism and photoelectric signal characteristics of moire fringe as well as electronic subdivision principle are studied and analyzed detailedly. A new type of single-track absolute encoding method suitable for applying to metal code disc is put forward, Ten readouts are evenly distributed in one single track to achieve0°～360°full scale absolute encoding according to single-track periodic gray code encoding method. The code disc and slit disc are designed. The method for calibrating the coarse code of single-track periodic gray code is put forward, the program for calibration is compiled and it can achieve calibration for the coarse code by the fine code.The hardware structure and software program of a high speed data acquisition and processing system suitable for the new code disc is designed based on FPGA of Xilinx corp to achieve the acquision and processing. A prototype of miniature single-track absolute rotary encoder is developed and the accuracy of prototype is detected.The resolution of the encoder with its volume φ48×40mm can reach5.27arcseconds. Its accuracy can reach20arcseconds. The result show that the method researched in this paper was feasible and had an important reference value for developing miniature absolute matal photoelectric encoder, and had a great significance in terms of enhance the performance of encode.