Research On Automatic Compensation Technique Of Moire Fringe Photoelectric Signal

In order to improve the precision of tracking weapons and equipment and thepositioning accuracy of satellite navigation system, the research of high-resolutionabsolute photoelectric shaft encoder with high accuracy under complex workingconditions is needed. And this becomes a difficulty in the military industry. The anglemeasurement accuracy of photoelectric shaft encoder is mainly subject to thesubdivision precision of Moire fringe photoelectric signal. And the subdivisionprecision depends on the quality of Moire fringe precise code signal. So the researchof automatic compensation technology is to be of significance to realize the highaccuracy and high resolution of photoelectric shaft encoder.By reading domestic and foreign literature, the composition of Moire fringephotoelectric signal of high-precision encoder is discussed. Fundamental factorswhich lead to the deviation of Moire fringe photoelectric signal and the spatialdistribution characteristic of subdivision error which is caused by the deviation ofMoire fringe photoelectric signal are also discussed. The key point of automaticcompensation method of Moire fringe photoelectric signal is pointed out.The method of real-time compensation of orthogonality deviation for the Moirefringe photoelectric signal based on Hilbert transform theory was proposed. Dynamicmeasurement algorithm for the orthogonality deviation of same frequencyphotoelectric signal using Hilbert transform theory was constructed. In the light ofmathematical model for Moire fringe photoelectric signal, lookup table for angle codecompensation was established and the synchronous processing mode was adopted,real-time compensation of orthogonality deviation for the photoelectric signal wasachieved. The method of automatic compensation of sine deviation for the Moire fringephotoelectric signal based on the particle swarm optimization algorithm was proposed.The main harmonic components of sine deviation for high precision photoelectricencoder signal using Fourier algorithm were revealed, waveform equation wasestablished and compensation model of subdivision error was set up. Theidentification method for signal waveform parameter based on particle swarmoptimization algorithm was designed. Automatic compensation of sinusoidal deviationfor the photoelectric signal was achieved.The automatic compensation system for Moire fringe photoelectric signal wasestablished. The automatic compensation method of DC level drift and the amplitudeof deviation for Moire fringe photoelectric signal was proposed. Automaticcompensation method of each error for Moire fringe photoelectric signal wasresearched and syncretized. A comprehensive compensation model of the Moire fringephotoelectric signal subdivision error was established. The comprehensive automaticcompensation of the Moire fringes photoelectric signal was realized. It can improvethe subdivision accuracy, environmental adaptability and reliability of the encoder.Moire fringe photoelectric signal of high precision photoelectric encoder wascompensated and analysed using this method of this paper research, it was sufficientto the technical index of the quality for high precision encoder Moire fringephotoelectric signal. To conduct an experiment, the subdivision error of the Moirefringes photoelectric signal for a24-bit photoelectric encoder was reduced0.61". Theexperimental results showed that the method of automatic compensation of this paperresearch can improve the subdivision accuracy, environmental adaptability andreliability of the encoder. The automatic compensation system can be used as thepreparation processing system or error diagnosis system of the encoder, it is verypractical for development of photoelectric shaft encoder ultra high precision andimprove the angle stability of photoelectric encoder.