基于线结构光的航空发动机叶片三维形貌测量技术研究

发布时间：2018-08-16 09:24

【摘要】：叶片是航空发动机内部的一种重要组成零件,若要确保航空发动机在工作期间安全运转,就必须保证叶片具有高质量、高性能以及高寿命。近年来,因发动机叶片断裂导致的航空飞行事故屡有发生,叶片断裂又被称为航空发动机事故的“第一杀手”。叶片是一类具有典型自由曲面的零件,它自身的质量、性能以及使用寿命完全由其表面形状决定。因此,针对其表面三维形貌检测的研究就显得极其重要。目前在航空发动机叶片表面三维测量领域,国内外学者做了大量实验研究,提出了许多的解决措施,并且针对不同类型叶片的测量都具有其独特的优势,然而就当前航空工业领域的高精度、高功效、自动化、价格低廉等要求而言,这些措施还难以同时实现。所以,探索一系列能够实现自动化、低成本、高精度、高效率的航空发动机叶片三维测量方法是当前的研究热点。本文针对航空发动机叶片表面三维形貌测量,提出了一种基于线结构光的三维扫描测量方法,并且进行了深入研究与探讨。第一,分析了线结构光三维测量技术的原理,建立了线结构光三维测量系统模型,并在该模型的基础上设计了一套线结构光三维扫描测量系统。第二,深入研究了系统标定技术,采用张氏二维相机标定法标定相机内外参数,采用基于自由移动二维标靶的交比不变法标定线结构光视觉传感器结构参数。第三,研究了一种降低航空发动机叶片表面高光反射的多项式拟合法,详细分析了影响激光条纹图像质量的各种干扰因素,并提出解决方法。第四,提出了一种基于几何中心法和高斯分解的改进hessian矩阵激光条纹中心提取方法,利用几何中心法提取激光条纹图像每行的左右边界位置,将原始hessian矩阵中的二维高斯卷积运算分解为两个相乘的一维高斯卷积运算,并构造新的hessian矩阵准确提取激光条纹中心。第五,利用本文设计的线结构光三维扫描测量系统进行航空发动机叶片表面三维形貌测量实验,分析了实验结果及误差,并在此基础上设计了一套航空发动机叶片三维检测仪器的机械结构模型。本文以线结构光三维测量技术为原理,提出了测量航空发动机叶片表面三维形貌的方法,并进行了实验研究,结果表明该方法能有效测量航空发动机叶片的表面三维形貌。利用本文提出的改进hessian矩阵激光条纹中心提取法能够实现航空发动机叶片的低成本、高效率三维测量,并且结合本文设计的叶片三维检测仪器机械模型,为后续实现航空发动机叶片的自动化、高精度测量提供了理论基础。
[Abstract]:Blade is an important part of aero-engine. In order to ensure the safe operation of aero-engine during work, it is necessary to ensure the blade with high quality, high performance and long service life. In recent years, aeronautical flight accidents caused by engine blade breakage occur frequently, and blade breakage is also called "the first killer" of aero-engine accidents. Blade is a kind of parts with typical free-form surface. Its quality, performance and service life are completely determined by its surface shape. Therefore, it is very important to study the three-dimensional morphology detection of its surface. At present, in the field of aero-engine blade surface 3D measurement, domestic and foreign scholars have done a lot of experimental research, put forward a lot of solutions, and the measurement of different types of blades has its unique advantages. However, it is difficult to achieve these measures at the same time for the requirements of high precision, high efficiency, automation and low price in the field of aviation industry. Therefore, to explore a series of automatic, low cost, high precision, high efficiency aero-engine blade 3D measurement method is the current research focus. In this paper, a 3D scanning measurement method based on linear structured light is proposed for measuring the surface of aero-engine blade, and it is deeply studied and discussed. First, the principle of linear structured light 3D measurement technology is analyzed, and the model of line structured light 3D measurement system is established. Based on the model, a set of line structured light 3D scanning measurement system is designed. Secondly, the system calibration technology is deeply studied. The calibration method of Zhang's two-dimensional camera is used to calibrate the internal and external parameters of the camera, and the intersection ratio invariant method based on the free-moving two-dimensional target is used to calibrate the structural parameters of the line structured light vision sensor. Thirdly, a polynomial fitting method to reduce the specular reflection on the surface of aero-engine blades is studied. The interference factors affecting the image quality of laser stripes are analyzed in detail, and the solutions are proposed. Fourthly, an improved hessian matrix laser fringe center extraction method based on geometric center method and Gao Si decomposition is proposed. The geometric center method is used to extract the left and right boundary position of each line of laser stripe image. The two-dimensional Gao Si convolution operation in the original hessian matrix is decomposed into two multiplied one-dimensional Gao Si convolution operations, and a new hessian matrix is constructed to accurately extract the laser stripe center. Fifthly, the 3D scanning measurement system of linear structured light is used to measure the surface of aeroengine blade, and the experimental results and errors are analyzed. On the basis of this, a mechanical structure model of three-dimensional measuring instrument for aeroengine blade is designed. In this paper, based on the principle of linear structured light 3D measurement, a method for measuring the surface 3D morphology of aero-engine blades is proposed. The experimental results show that the method can effectively measure the three-dimensional morphology of aeroengine blades. The improved hessian matrix laser stripe center extraction method proposed in this paper can realize the low cost and high efficiency 3D measurement of the aeroengine blade, and combine the mechanical model of the blade 3D detection instrument designed in this paper. It provides a theoretical basis for automatic and high precision measurement of aero-engine blades.
【学位授予单位】：南昌航空大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：V263.6;TP391.41

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