光电编码器莫尔条纹测速方法研究

	光电编码器莫尔条纹测速方法研究
其他题名	Research of Velocity Measurement forPhotoelectric Encoder Based on Moiré Fringe
	王亚洲
学位类型	硕士
导师	万秋华
	2015-10
学位授予单位	中国科学院大学
学位专业	机械电子工程
关键词	莫尔条纹光电信号精密测速希尔伯特-黄变换光电编码器
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。
其他摘要	Photoelectric encoder is a kind of angular displacement sensor by using grating moiré fringe. By utilizing the relative displacement of the grating, and by adopting optic and electronic subdivision, the encoder can translate displacement information into corresponding digital signal output. They can accomplish tasks like high accuracy measurement of rotation angle, speed, and acceleration. They have been widely used in fields such as industrial control, automatic detection and precision measurement, due to its advantages of high accuracy, small volume, anti-jamming, long life, etc. In high precision measurement control system, the speed feedback of the photoelectric encoder is extremely important, thus acquiring accurate speed information of the photoelectric encoder is of great significance. In order to get the real-time speed of photoelectric encoder more accurately, this paper analyzed and studied the measurement methods based on moiré fringe signal. By consulting a large number of papers on speed measurement home and abroad, a speed measurement method based on moiré fringe is proposed on the premise of understanding their merits and flaws. After the analysis of the principle and theory of the generating of moiré fringe photoelectric signal, and its error types, the impacts of moiré fringe photoelectric signal error to the accuracy of speed measurement is deduced. A total differential speed measuring method based on moiré fringe signal of photoelectric encoder is proposed, and the impacts that influence the accuracy of speed measurement is analyzed. Starting from the perspective of the moiré fringe photoelectric signal, joined with the calibration algorithm, the speed of the photoelectric encoder is obtained by adopting total differential operation. In the process of speed calculation, the angle output is not essential, which has effectively reduced the accuracy loss of speed measurement caused by angle measurement error. The angle and speed information can be obtained simultaneously, so that the time delay of the system is reduced. Another speed measuring method of single moiré fringe based on Hilbert transform is proposed. The generation process of moiré fringe is studied, and the principle and merits of adopting Hilbert-Huang transform for the instantaneous frequency extraction are analyzed. The relation between the frequency and speed of the moiré fringe signal of photoelectric encoder is deduced. By Hilbert-Huang transform of the moiré fringe signal, the speed value of the photoelectric encoder is extracted. The method proposed can completely avoid speed measurement error caused by Orthogonal and continuous error and the impact of dc component of the moiré fringe signal, which has effectively improved the velocity accuracy. The two speed measurement methods are applied to some 21 bit photoelectric encoder produced by Chinese Academy of Sciences. By adopting total differential speed measuring method, under condition of lower speed delay, the root mean square error of the speed measurement is reduced from 0.0367 rad/s of M method to 0.0216 rad/s; by adopting single moiré fringe speed measurement method based on Hilbert transform, under the condition of a slight increase of measurement delay, the root mean square error is reduced from 0.0367 rad/s to 0.0134 rad/s of M method. The two moiré fringe speed measurement methods proposed in this paper is capable of improving the accuracy and stability of speed measurement of photoelectric encoders.
语种	中文
文献类型	学位论文
条目标识符	http://ir.ciomp.ac.cn/handle/181722/49263
专题	中科院长春光机所知识产出
推荐引用方式 GB/T 7714	王亚洲. 光电编码器莫尔条纹测速方法研究[D]. 中国科学院大学,2015.

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