光电编码器莫尔条纹测速方法研究

发布时间：2018-06-22 21:39

本文选题：莫尔条纹光电信号 + 精密测速　；参考：《中国科学院研究生院(长春光学精密机械与物理研究所)》2015年硕士论文

【摘要】：光电编码器是一种利用光栅莫尔条纹为测量基础的光电角位移传感器。利用光栅和码盘的相对位移从而产生莫尔条纹信号,通过光学细分和电子学细分,将位移转换成数字信号输出。通过与计算机相连可以实现角度、转速和角加速度的精密测量。光电编码器具有精度高、体积小、抗干扰、使用寿命长等优点,因此广泛用于工业控制、自动化检测及精密测量等领域。在高精度的测量控制系统中,光电编码器的转速是极其重要的反馈信息,因此,精确获取光电编码器的转速具有重要意义。为了更加精确的获得光电编码器的实时转速,本文对基于莫尔条纹光电信号的编码器测速方法进行了分析和研究。通过查阅大量国内外测速文献,在了解国内外编码器测速方法优缺点的前提下,提出了光电编码器莫尔条纹测速方法。通过分析莫尔条纹光电信号的生成原理及误差种类,推导出莫尔条纹光电信号误差对测速精度的影响。提出了基于莫尔条纹光电信号的全微分测速方法,分析了影响编码器测速精度的因素,从莫尔条纹光电信号入手,加入了修正算法,通过全微分运算得到光电编码器的速度。在速度计算过程中,不需要编码器的输出角度,有效的降低了编码器测角误差对编码器测速精度的影响,实现了编码器角度和速度的同时输出,有效降低了系统的测速延时。提出了基于希尔伯特-黄变换的单莫尔条纹测速方法,研究了编码器莫尔条纹光电信号的产生原理,以及希尔伯特-黄变换在瞬时频率提取上的原理和优势。推导出编码器输出的莫尔条纹光电信号频率与转速之间的关系式。然后将莫尔条纹光电信号通过希尔伯特-黄变换,提取出光电编码器的速度值。该方法可以避开光电编码器正交性误差和等幅性误差带来的测速误差,避免莫尔条纹信号直流分量带来的测速误差,有效的提高测速精度。将本文提出的两种编码器测速方法应用到中科院生产的某型号21位光电编码器上,利用全微分测速方法在不降低测速延时的情况下,将测速均方根误差由M法所测得的0.0367rad/s降低到0.0216rad/s。利用基于希尔伯特变换的单莫尔条纹测速方法,在测速延时略有增加的情况下,将测速均方根误差由M法所测得的0.0367rad/s降低到0.0134rad/s。本文提出的两种莫尔条纹测速方法能够提高编码的测速精度及稳定性
[Abstract]:Photoelectric encoder is a photoelectric angular displacement sensor based on grating moire fringe. The moire fringe signal is generated by using the relative displacement of the grating and the code disk. The displacement is converted into digital signal output by optical subdivision and electronic subdivision. The precise measurement of angle, rotational speed and angular acceleration can be realized by connecting with the computer. Photoelectric encoder has the advantages of high precision, small volume, anti-interference and long service life, so it is widely used in industrial control, automatic detection and precision measurement. In the high precision measurement and control system, the speed of the photoelectric encoder is very important feedback information, so it is very important to accurately obtain the speed of the photoelectric encoder. In order to obtain the real-time rotational speed of photoelectric encoder more accurately, this paper analyzes and studies the speed measurement method of encoder based on moire fringe photoelectric signal. Based on a large number of domestic and international literature on speed measurement, and on the premise of understanding the advantages and disadvantages of the speed measurement methods of encoder at home and abroad, the moire fringe velocity measurement method of photoelectric encoder is put forward. By analyzing the generating principle and error types of moire fringe photoelectric signal, the influence of Moir 茅 fringe photoelectric signal error on the accuracy of velocity measurement is deduced. This paper presents a full differential velocity measurement method based on moire fringe photoelectric signal, and analyzes the factors that affect the accuracy of encoder speed measurement. Starting from moire fringe photoelectric signal, a modified algorithm is added, and the speed of photoelectric encoder is obtained by full differential operation. In the process of speed calculation, the influence of the angle error of encoder on the accuracy of speed measurement is reduced effectively without the need of the output angle of encoder, and the output of both angle and speed of encoder is realized, and the delay of measuring speed of the system is reduced effectively. A single moire fringe velocimetry method based on Hilbert-Huang transform is proposed. The principle of generating moire fringe photoelectric signal of encoder and the principle and advantage of Hilbert-Huang transform in instantaneous frequency extraction are studied. The relation between frequency and speed of moire fringe photoelectric signal output by encoder is deduced. Then the moire fringe photoelectric signal is extracted by Hilbert-Huang transform and the velocity of the photoelectric encoder is extracted. This method can avoid the speed measurement error caused by the orthogonality error and the constant amplitude error of the photoelectric encoder, avoid the velocity measurement error caused by the DC component of moire fringe signal, and effectively improve the speed measurement accuracy. Two kinds of encoder speed measurement methods proposed in this paper are applied to a certain type of 21 bit photoelectric encoder produced by the Chinese Academy of Sciences. The full differential velocity measurement method is used without reducing the time delay of velocity measurement. The root mean square error of velocity measurement is reduced from the 0.0367rad/s measured by M method to 0.0216radr / s. Using the single moire fringe velocimetry method based on Hilbert transform, the root mean square error (RMS) of velocity measurement is reduced from the 0.0367rad/s measured by M method to 0.0134 radr / s with a slight increase in the velocimetry delay. The two moire fringe velocimetry methods presented in this paper can improve the accuracy and stability of coded velocimetry.
【学位授予单位】：中国科学院研究生院(长春光学精密机械与物理研究所)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN762

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