光电位移信号新型细分方法及系统设计

为提高光电轴角编码器的分辨力，提出一种新型莫尔条纹信号细分方法并建立基于FPGA的光电位移信号倍频系统.根据理想莫尔条纹光电信号的数学模型，利用多倍角正余弦信号的函数性质，将原始莫尔条纹信号推导为n倍频的高阶信号；由幅值细分理论，离线建立基于高阶正余弦信号的高分辨力幅值细分查找表；根据增量式、绝对式光电编码器的不同功能，分别阐述了应用该幅值细分查找表实现编码器高分辨力的倍频技术；同时又指出本文细分方法应用的约束条件.最后，以直径为40mm，分辨率为2500P/R的欧姆龙E6B2-CWZ6C增量式光电编码器为实验对象，在转速范围200~3000rpm的同步电机驱动下，编码器输出波形频率范围约为8.3kHz~125kHz，在基于频率为10kHz的模拟输入信号下，采用本文细分方案设置四倍频设计实验，该系统可以快速将频率增加到原来频率的4倍；同时，基于4倍频原理设计了128倍频实验，并进行实验验证，同样得到该系统可以快速增加到输入频率的128倍.该设计方法及系统与传统细分方法相比较，具有开发周期短、集成度高、模块化、速率快等特点.

New Subdivision Method and System Design of Photoelectric Displacement Signal

In order to improve the resolution of photoelectric shaft angle encoder,a method of subdividing high frequency-doubling Moire fringe signal is proposed and a frequency-doubling system of photoelectric potential shift signal based on FPGA is established.According to the mathematic model of ideal Moire fringe photoelectric signal,the original Moire fringe signal is deduced into n-fold high-order signal by using the function property of multi-angle sine-cosine signal.The different functions of the encoder are described,and the frequency doubling technique of high resolution by using the amplitude subdivision lookup table is described respectively.Finally,an Omron E6B2-CWZ6C incremental photoelectric encoder with a diameter of 40 mm and a resolution of 2500 P/R is taken as the experimental object.Driven by a synchronous motor with a speed range of 200~3000 rpm,the output waveform frequency range of the encoder is about 8.3 kHz~125 kHz.Under the analog input signal with a frequency of 10 kHz,the subdivision scheme is adopted.In the quadruplicated frequency doubling experiment,the system can increase the frequency to 4 times of the original frequency.At the same time,based on the principle of 4 times frequency,the 128 times frequency experiment is designed and verified by experiments.The system can also be quickly increased to 128 times the input frequency.Compared with the traditional subdivision circuit,the design method and system have the characteristics of short development cycle,high integration,modularization and simple modification.