近似三角波莫尔条纹光电信号的细分误差修正

Interpolation Error Correction of Moiré Fringe Photoelectric Signals in the Approximate Form of Triangle Wave

为提高小型光电编码器精度,研究了一种精码莫尔条纹光电信号细分误差修正方法。建立单路信号波形参数方程,对采样信号进行傅里叶变换求出波形参数,利用多倍角公式将信号波形中的高次谐波分量变换为高阶分量,通过牛顿迭代法将莫尔条纹光电信号修正至标准正余弦信号;建立正弦、余弦两路信号的相位误差修正模型,利用最小二乘拟合法求解出相位误差修正参数,实现对莫尔条纹光电信号正交性误差的修正。采用该方法对某16位小型光电编码器细分误差进行修正处理,经测试细分误差峰峰值由修正前的162.5″减小到修正后的47.5″。实验结果表明,研究的误差修正方法可以有效地减小细分误差,提高精度,对于研制小型化、高精度光电编码器具有重要意义。

To improve the precision of small photoelectric encoders, a lot of research is conducted on the interpolation error correction method of moiré fringe photoelectric signals. A parameter equation of single channel signal waveform is built firstly, and then Fourier transform is performed on sampled signals to get the waveform parameters. The high spatial harmonics in the signal waveform are transformed into higher order components using the multiple angle formula, and photoelectric signals are corrected to standard sine and cosine ones using the Newton iteration method. After that, a phase error correction model of the sine and cosine signals is built, phase error correction parameters are then solved using the least squares fitting method, and finally the phase error correction of the photoelectric signals are realized. The interpolation error correction of a 16-bit small photoelectrical encoder is carried out. The result demonstrates that, it can effectively reduce interpolation error and improve the precision, which is important in the development of small and high-precision photoelectrical encoders.