基于结构光的大物体三维测量关键方法的研究

发布时间：2018-04-17 06:45

本文选题：三维拼接测量 + 周期校正　；参考：《南昌航空大学》2016年硕士论文

【摘要】：三维测量在现代工业制造包括产品尺寸检测、产品质量控制、逆求工程、机器人视觉、人脸识别、3D打印及其他工业生产中都具有广泛的应用。基于结构光的条纹投影轮廓术由于其非接触、全场测量和易于信息处理等优点,受到诸多相关学者探讨与研究,在三维测量中具有重要意义。随着科技的发展,大面型尺寸的测量、检测逐渐成为工业产品制造的关键问题和发展趋势,并成为三维测量领域新的研究热点。如在航空航天领域,飞机、发动机叶片等,在交通运输领域,汽车、船舶等,其测量面积大,被测面复杂,精度要求高,传统的三维测量方法很难满足该领域的测量要求。基于结构光的大物体三维拼接测量方法在其完整的三维信息获取方面有着重要意义。针对大物体三维测量,当采用相交轴测量系统时,通常出现如下问题。第一,受其远距离、大视场、复杂大幅面等测量条件的影响,参考平面上的投影光栅条纹周期展宽严重,另外,CCD镜头的非线性畸变等,都将影响大物体三维面形测量精度。第二,受大物体几何尺寸的约束,其单幅面测量范围受限,无法通过一次性测量获得其完整三维信息。故本文将从下面几个问题进行相关探讨和研究:由于CCD镜头非线性畸变的存在,采用了一种有效的CCD镜头畸变校正方法。自CCD相机标定基础上,建立基于牛顿迭代法的CCD相机镜头畸变校正模型。同时改进提出了一种灵活、简单的,利用已标定的相机来标定投影仪的方法。根据大物体的相位解包裹和参考平面上投影条纹周期的变换规律,采用了一种基于参考平面上条纹周期校正的时间相位展开法的理论模型,在保证其高精度的情况下完成被测物单幅面三维测量。利用单目视觉三维拼接技术,分别采用基于全局坐标系与LM优化算法结合的标志点坐标转换拼接方法和基于柱坐标系的大物体三维拼接测量方法,获得大物体完整的三维数据,弥补其单幅面测量受限问题。实验结果表明,本文所使用的CCD镜头畸变校正方法对其非线性畸变校正有良好的效果。基于条纹周期校正的时间相位展开法,在实现参考平面投影条纹周期校正基础上,能准确获取被测面面形,提高测量精度。在结构光单目三维测量中,基于全局坐标系与LM优化结合的标志点坐标转换拼接和基于柱坐标系的大物体三维拼接实验中,均能有效的完成大物体的三维拼接测量,其整体拼接测量精度为0.20mm。误差在允许范围之内,能够精确的完成大物体三维拼接测量。
[Abstract]:3D measurement is widely used in modern industrial manufacturing, including product size detection, product quality control, reverse engineering, robot vision, face recognition 3D printing and other industrial production.Fringe projection profilometry based on structured light has been discussed and studied by many relevant scholars because of its advantages of non-contact, full-field measurement and easy information processing, which is of great significance in three-dimensional measurement.With the development of science and technology, the measurement of large surface size has gradually become the key problem and development trend of industrial product manufacturing, and has become a new research hotspot in the field of three-dimensional measurement.For example, in the field of aerospace, aircraft, engine blade and so on, in the field of transportation, automobile, ship and so on, the measurement area is large, the measured surface is complex, and the precision is high. The traditional three-dimensional measurement method is difficult to meet the measurement requirements in this field.The measurement method of 3D splicing of large objects based on structured light is of great significance in obtaining the complete 3D information.When using the intersection axis measurement system, the following problems usually occur in the three-dimensional measurement of large objects.First, due to its long distance, large field of view, complex large format and other measuring conditions, the period of projection grating fringe on the reference plane is widened seriously, and the nonlinear distortion of CCD lens will affect the measurement accuracy of large object.Second, restricted by the geometric size of large object, the measurement range of single format is limited, and the complete 3D information can not be obtained by one time measurement.Therefore, this paper will discuss and study the following problems: due to the existence of nonlinear distortion of CCD lens, an effective CCD lens distortion correction method is adopted.Based on the calibration of CCD camera, the lens distortion correction model of CCD camera is established based on Newton iteration method.At the same time, a flexible and simple method to calibrate the projector by using the calibrated camera is proposed.According to the phase unwrapping of large objects and the transformation of the period of projection fringes on the reference plane, a theoretical model of time phase unwrapping method based on the correction of the period of fringe on the reference plane is adopted.In order to ensure its high accuracy, the single-format three-dimensional measurement of the object under test is completed.By using the monocular vision 3D splicing technology, the marking point coordinate transformation and splicing method based on the global coordinate system and LM optimization algorithm and the large object 3D splicing measurement method based on the cylindrical coordinate system are adopted, respectively, to obtain the complete 3D data of the large object.Make up for the limited problem of single format measurement.The experimental results show that the CCD lens distortion correction method used in this paper has a good effect on the nonlinear distortion correction.Based on the time phase unwrapping method of fringe periodic correction, based on the reference plane projection fringe period correction, the surface shape can be accurately obtained and the measurement accuracy can be improved.In the monocular 3D measurement of structural light, the coordinate conversion and splicing of mark points based on the combination of global coordinate system and LM optimization and the experiment of 3D splicing of large objects based on cylindrical coordinate system can effectively complete the 3D splicing measurement of large objects.The accuracy of the whole splicing measurement is 0.20mm.The error is within the allowable range, and the measurement of large objects can be completed accurately.
【学位授予单位】：南昌航空大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TP391.41

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