A method for detection and quantification of meshing characteristics of harmonic drive gears using computer vision

• Published in: Science China. Technological sciences Vol. 59; no. 9; pp. 1305 - 1319
• Main Authors: Ma, DongHui, Wu, JiaNing, Yan, ShaoZe
• Format: Journal Article
• Language: English
• Published: Beijing Science China Press 01.09.2016; Springer Nature B.V
• Subjects: Computer vision; Engineering; Gear teeth; Harmonic drive gears; High speed cameras; Image processing; Kinematics; Low speed; Meshing; Product design; Rotation; Stiffness; 合成标准不确定度; 啮合特性; 物理数学模型; 视频图像序列; 计算机视觉检测; 谐波齿轮传动; 高速摄像系统; 齿轮传动机构; image processing; uncertainty analysis; kinematics analysis; gear engagement; harmonic drive gear; computer vision
• ISSN: 1674-7321; 1869-1900
• DOI: 10.1007/s11431-016-6082-6

A lack of accurate description of the meshing characteristics and the corresponding frictional mechanism of the harmonic drive gear has limited progress toward modeling the hysteresis stiffness. This paper presents a method for detection and quantifica- tion of the meshing characteristics of the harmonic drive gear based on computer vision. First, an experimental set-up that in- tegrates a high speed camera system with a lighting system is developed, and the image processing is adopted to extract and polish the tooth profiles of the meshed teeth pairs in each acquired video sequence. Next, a physical-mathematical model is es- tablished to determine the relative positions of the selected tooth pair in the process of the gear engagement, and the combined standard uncertainty is utilized to evaluate the accuracy of the calculated kinematics parameters. Last, the kinematics analysis of the gear engagement under the ultra-low speed condition is performed with our method and previous method, and the influ- ence of the input rotational speed on the results is examined. The results validate the effectiveness of our method, and indicate that the conventional method is not available in the future friction analysis. It is also shown that the engaging-in phase is ap- proximately a uniform motion process, the engaging-out phase is a variable motion process, and these characteristics remain unchanged with the variation of the input rotational speed. Our method affords the ability to understand the frictional mecha- nism on the meshed contact surfaces of the harmonic drive gear, and also allows for the dynamic monitoring of the meshing properties.