The Design And Analysis Of The Composite Optical Encoder With High-precision

With the development of measurement and control technology, the higher demand on optical rotary encoder is put forward. Some control systems demand the encoder not only outputs high-precision position information, but also provide its sine signal and cosine signal whose phase has a difference of 90 degree for the servo system. At the same time it also requests that the encoder should have a large bore hollow shaft, and small size, which can adapt to harsh working environment. In this paper, the composite high-precision optical encoder is designed. It is an important and practical application for precise positioning control system, velocity control and small size in the harsh working environment.On the base of studying home and foreign reference materials, we deeply analyze the characteristics and the affect on the accuracy of the light source, encoder disc, shafting, electrical process and coupling. We get the conclusion that the key to achieve high-precision angle measuring accuracy and velocity control is to improve the accuracy of encoder disc and shafting, to improve the optical signal quality, and to improve the coupling. On this basis, we carry out a high-precision composite optical shaft encoder design.Combining the actual condition of basic industry in our country, we design the shafting using the close packing ball bearing and the close-packing arranging bearing. At the same time the length of the shafting is decreased. As a result, the high-precision large hollow shaft Precision shaft is accomplished.Based on Moiréfringe theory, the three correction methods was used to design high-precision optical encoder to improve the encoder angle and velocity accuracy, as well as to reduce the equipment volume.According to temperature characteristics of the solid light emitting diode ,the temperature compensation circuit is designed to ensure the stability of optical signal amplitude at -40℃～+60℃; The zero position circuit is designed, so that the absolute speed of zero and zero angle bit precision align, meeting the requirements of servo control system.Through modal analysis and stress analysis, the force on the coupling conditions were analyzed to optimize the structural design, and design a flexible coupling high-precision。Using the methods put forward in this paper, we design high-precision composite optical encoder with hollow shaft ofφ150,precision ofσ≤2〞, can output the absolute position's information and the sine signals and cosine signals whose phase difference of 90°. Experiments show that the study of high-precision composite optical encoder has the characteristics of small size, high precision, and suitable for harsh working environment. It has practical value to improve the control precision measurement and control system.