Fast Evaluation Of Optical Encoder's Interpolation Errors

With the application of optical encoders in technology,national deference,space, the demand of the targets to photoelectric rotary encoders is higher and higher. Errors of angular measurement are the important index of optical encoder, the interpolation errors are the main component of the errors. The calibration of the interpolation errors is required in rigorous lab condition. If the experimental condition is dynamic, the period of code disc is small or the interpolating units are large, there is no mature way to evaluate the interpolation errors.A dynamic evaluation method of interpolation errors in photoelectric encoder is described in the article. While the photoelectric encoder is uniform motion, the data acquisition card samplings two photoelectric signal with a phase difference ofπ/2, then the two signals are processed to be equiangular data and harmonic analysis to calculate the waveform parameters of signal equations. Finally, the signal waveform equations are put into the interpolation error equations to make out the interpolation errors. Experimental results show that the method is effective.With the combine of the software and hardware, using Visual Basic 6.0 designs the measuring data analysis program. The program could realize real-time sampling, harmonic analysis of photoelectric signals, evaluation of the interpolation errors and the quality of signals, and it provides the good interface of person-computer.In general, the method can implement the dynamic measurement about the interpolation errors evaluation. The significance of the system is that it could evaluate optical encoders on practical applications.