非均匀采样光电编码器莫尔条纹信号分析方法

为实现高精度光电编码器非匀速转动时动态细分误差的检测,提出了一种基于非均匀采样的莫尔条纹光电信号分析方法.首先,利用曲线拟合的最小二乘法将采集到的编码器非均匀信号数据重构出真实的信号波形.然后,根据离散傅里叶变换算法分析重构信号,同时推导出信号的频率、幅值和相位的计算表达式,运用软件仿真评估算法可行性.最后,采用该方法对某21位绝对式光电轴角编码器精码信号进行分析,根据信号参数与细分误差的关系获得动态细分误差,其细分极值误差为+2.41"和-3.08".实验结果表明,该方法利用信号重构和傅里叶变换算法得到信号参数,真实的反应了莫尔条纹信号质量,在编码器非匀速转动时,可有效地测量动态细分误差,为实际工作现场编码器精度误差的实时检测奠定了基础.

A Method of Analysis Based on Morié Fringe Signals of Optical Encoder with Non-uniform Sampling

In order to realize the detection for dynamic interpolation error in high-precision optical encoder with non-uniform rotation, a method of analysis based on morié fringe photoelectric signals with non-uniform sampling is presented.First, the real signal waveform is reconstructed with collecting non-uniform signal data of encoder in the method of least squares curve fitting.Then, according to the discrete Fourier transform algorithm analyzing reconstructed signal, meanwhile deducing the calculation expression of frequency, amplitude and phase.The feasibility of the algorithm is assessed with software emulation.Finally, the precise code signal of a 21-bit absolute rotary optical encoder is analyzed.Dynamic interpolation error is obtained based on relationship between the signal parameters and interpolation error.Interpolation extreme errors are +2.41" and -3.08".Experiment result shows that, the signal parameters are obtained with using signal reconstruction and Fourier transform algorithm, that reflects the real morié signal quality.This method can effectively measure the dynamic interpolation error while the encoder is non-uniform rotation, which establishes foundation of real-time detection of encoder error at the actual work site.