Research On Compensation Method Of Amplitude And Phase Deviation For High Precision Encoder

In recent years,there is an increasing need to control rotary motion,as a result photoelectric encoders are widely used.It also puts forward higher standards for the precision and resolution of photoelectric encoders.The angular accuracy of the photoelectric axis-angle encoders mainly depends on the subdivision precision of the moiré fringe photoelectric signals,and the subdivision accuracy is limited by the moiré fringe photoelectric signals' quality.As a result,signal compensation technology have been developed for the main deviations in the moiré fringe photoelectric signals,which is of great significance for improving the accuracy of photoelectric encoders.The principle of photoelectric encoders and the four main deviations which affect the subdivision accuracy are introduced.The research status of signal compensation technology at home and abroad is summarized.The advantages and limitations of given compensation methods are analyzed,the generation principle and subdivision principle of the moiré fringe photoelectric signals are studied.The influence of four subdivision deviations on the subdivision precision is analyzed.These make a guiding role for the further research on the automatic compensation method for the staple deviations.New deviation models of the moiré fringe photoelectric signals are proposed.A real-time deviation measurement method for the orthogonality deviation and amplitude deviation of the signals is proposed.In this way,a real-time rapid measurement of the signal deviation is achieved,which provides reliable deviation data for later deviation compensation method.The principle of the closed-loop feedback subdivision algorithm is analyzed.According to the existing of the deviations on actual signals,an improved closed-loop feedback subdivision algorithm is proposed.The compensation for signal deviations is directly implemented in the subdivision algorithm,which effectively reduces the subdivision error and improves the signal quality.The amounts of the code are greatly reduced,and the processor's storage and computational resources are saved.The signal processing circuit and signal processing software are designed.And a signal processing system is built.The Moiré fringe photoelectric signal of a type of 24-bit high-precision photoelectric axis-angle encoder produced by CIOMP is sampled and analyzed,and the compensation algorithm is debugged and verified.Then,a subdivision error detection system is built,and the subdivision error before and after compensation of the encoder signals is quantitatively measured.After comparison,the operation of the compensation algorithm makes the maximum value of the subdivision error of the signal reduced from 4.2 " to 1" and the standard deviation from 1.3 " to 0.43",which proves that the compensation algorithm can effectively improve the subdivision accuracy of the signal.The moiré fringe photoelectric signal deviation measurement method and the improved closed-loop feedback subdivision method proposed in this paper can improve the accuracy and stability of the encoder.