| Photoelectric shaft encoder is a kind of high resolution precision angle measuring device. It is of high precision, low energy consumption, and of the advantages of strong anti-jamming capability, thus has been widely used in industry, science, national defense, etc. With the rapid development of our national defense and industrial automation technology, the demand for photoelectric encoder is increasing. Photoelectric encoder error needs to be detected both before and during its use process. Error detection is a complicated process especially for mass production of photoelectric encoders. This paper has designed a small automatic photoelectric encoder error detection system, to improve the efficiency of encoder error detection, become more automation, and reduce man participation simultaneously.Existing error detection methods for photoelectric encoder are analyzed on the basis of referent papers home and abroad, their merits and flaws are compared. The principle of the photoelectric encoders and the reasons that induce error are studied, which provide the theory foundation for the study of error auto detection.A fault code automatic detection system for small photoelectric encoder is designed. The system is mainly composed of the encoder to be detected, motor drive system, system processing circuits, a computer and etc. The fault code automatic detection method is introduced, and it adopts comprehensive statistical algorithm combined with differential algorithms to realize automatic encoder error detection.The processing circuits of detection system, with the master chip of XC3S400 FPGA, has realized high speed data acquisition by series/parallel interface, error judgment using differential algorithms, display through the LED LCD monitor and transmission with computer. The system designed has improved the sampling frequency of encoder data, the efficiency and accuracy of error detection.The processing software is designed based on VHDL language to accomplish tasks of data acquisition, processing, display data transmission, error detection, result display and storage, making the results more intuitive and reliable.The mechanical parts such as the base, support, and locating ring are designed. The experimental platform has been set up, making the system convenient, small and portable.The method proposed in this paper has been successfully applied to some 15-bit photoelectric encoders to realize fault code detection at different speeds. The experimental results show that: the method proposed in this paper can be used for volume production of photoelectric encoder because of its high degree of automation and less manual operation. The fault code detection system is of high efficiency with the detection time has been shortened by 3 to 5 times. The system is portable, suitable for laboratory and other various work situations and it will provide great reference value to the development of automatic error detection for photoelectric encoder. |
