The Research Of The Method Of Photoelectric Signal Compensation For High-precision Shaft Encoder

With the the development of technology , especially in spaceflight and aviation, the requirement of tracking and collimating target fastly and accurately, the demand of the targets to the photoelectric shaft encoders is higher and higher. At present, the primary technology to improve the encoders' resolution is the interpolation technology of the photoelectric signal. The interpolation errors of the photoelectric signal have worked on the whole precision of encoder greatly for high-resolution high-accuracy photoelectric rotary encoders.Form and characteristic of photoelectric signal is introduced,interpolation technology of the photoelectric signal is described, the interpolation errors because of parameters of the photoelectric signal is analyzed , the essentiality of accruing the precision of encoder through photoelectric signal compesation by datas from experiments is illuminated.The paper introduces the methode of photoelectric signal compesation base on automatic gain control and sampling by phase locked loop frequency synthesizer . The principle automatic gain control and phase locked loop is expatiated detailedly by mathematic model. The feasibility of modifying the error of two photoelectric signals by software is also argued. Furthermore, studying the hardware of the system, including the performance of microcomputer (ADuC812) , parameters of variable-gain amplifier AD603, the structure of frequency synthesizer and other questions. At last, studying the software of the system, presenting chart of main-program and sub-program, discussing the main function of sampling data, controlling feedback and managing data modules, showing the results of experiments.The main innovations are described as follows:Variable-gain amplifier instead of traditional potentiometer , realizing automatic compensation of photoelectric signal, enhancing the reliability and maintainability of the system;Through sampling by phase locked loop frequency synthesizer, the precision of phase angle error is guaranteed;The method of photoelectric signal compensation includes all infections of photoelectric signal;The method of compesation is provided with real-time manipulation, high-precision, excellent anti-jamming . it can advance security and flexibility of photoelectric encoder specially in all kinds of atrocious conditions .