【作者】 杨金凤；

【导师】 马思乐；

【作者基本信息】 山东大学 ， 控制理论与控制工程， 2008， 硕士

【摘要】 由于基于机器视觉的检测技术具有非接触、实时、精度高等特点,因此近年来得到了迅速发展和广泛应用。空瓶检验系统是以机器视觉技术为基础,集光机电算于一体的检测设备。它以视觉检测代替传统的人工检测,实现对空瓶质量的检测。随着我国对食品安全日益重视且国外验瓶系统无法适应国内回收瓶质量参差不齐的现状,开发具有自主知识产权的空瓶检验系统即是国内啤酒生产企业的迫切需要,也是我国啤酒装备制造业发展的必然趋势。本文根据啤酒灌装的实际工艺以及检测系统的基本检测要求,设计了基于机器视觉的空瓶检验系统,详细分析了空瓶检测系统的组成结构和工作流程。主要对空瓶检验系统中的机器视觉技术进行了深入研究,详细探讨了图像采集的关键技术,开发了瓶口、瓶底及瓶壁图像的检测算法。本文的主要的研究工作如下:1、探讨了图像采集的关键技术,设计了能为空瓶检验系统提供清晰图像的图像采集系统。根据瓶壁图像采集的要求,设计了多级反射一次成像的光学成像装置,并分别应用于系统的入口和出口瓶壁检测,实现了瓶壁全方位检测。采用频闪光源照明并协调配合快门速度的方法以解决图像拖尾模糊的问题。2、根据高速检测的要求,提出仅对所采集图像中反映被检对象特征的区域进行处理的思路,开发快速、高效的算法以实现对检测区域的自动跟踪,实时确定图像中处理对象位置,减少对无用像素的处理,提高处理速度。3、针对瓶口外轮廓为圆形,成图像复杂多样的特点,文中首先探讨了瓶口图像处理区域的跟踪算法。通过对比分析确定了基于先验圆心的最小二乘圆拟合法瓶口处理区域跟踪算法。为实现高速检测,提出了基于连通域矩特征的缺陷特征提取方法,对提取特征进行统计决策分类,以排除噪声影响,得到正确的判别结果。实验数据表明上述算法能达到理想的检测准确率。4、在瓶底和瓶壁智能检测算法研究过程中,根据瓶颈位置边缘点成对出现的特点,对穿越瓶颈的特定直线进行线扫描,得到直线方向上灰度梯度最大的一组点,利用对称分析结合概率统计的方法对该组点进行分析,以确定瓶壁四部分的中心轴线位置,完成对瓶壁检测区域的跟踪。在瓶底检测中,采用最小二乘圆拟合方法对瓶底检测区域进行跟踪。提出瓶底和瓶壁多分区检测的思路,通过提取分区内的缺陷特征,应用统计决策判断的方法,对瓶底和瓶壁合格与否进行分类。实验证明该算法检测精度和速度能达到系统要求。5、在系统研究开发过程中,总结了实现空瓶检验系统实时、高速、准确检测的技术要点。主要包括合理配置硬件、设计快速高效的算法和各检测单元独立并行工作。更多还原

【Abstract】 The research on the vision-based inspection system has been developed greatly and used widely in recent years, which can be definitely ascribed to its advantages, such as non-contact and real-time performance, high accuracy, and so on. The empty bottle inspection system is the vision based intelligent inspection equipments integrated of optical, mechanical and electronical functions. The system performs well in quality inspection of empty bottle before beer filling instead of manual work. As the food safety draws more and more attention in China, and the foreign equipment for empty bottle inspection can’t meet the quality situation of the recycled bottles in our country, the research on empty bottle inspection system with full independent intellectual property rights becomes critical important, which willmeet the needs of the beer industry and the market.In this paper, the location of empty bottle inspection system on liquid filling lineis described. The design of the high-speed online bottle inspection system based on machine vision technology, the system architecture and principles are provided in details. Then some deep research on the machine vision system and key technologies for the image recognition system are presented, as well as an intelligent inspection algorithm for the recognition of the finish, base and sidewall of empty bottle. The contributions are summarized as follows:1. This paper analyzes the optical characteristics of the bottle flaws and studies the key technologies of image acquisition. Then it designs an image acquisition system providing the clear images for finish, base and sidewall of empty bottles respectively. Particularly the paper presents an optical imaging setting to implement omnidirectional image acquisition of sidewall. For the purpose of solving the problem that heavy-tailed images were captured as bottles moving under high-speed, the paper proposed a method with stroboscope cooperating with shutter speed.2. The main constraint is the real time operation as the bottles move continuously on the conveyer belt. Using images obtained from the camera, we just focus on the image area reflecting the characteristic of bottles. Then the proposed algorithm obtains the position of the bottles in the image and tracks the detection area precisely. The method is proved to be efficient in improving inspection speed.3. Based on the analysis of the characteristics of the finish bottle images, which shows the circle profile and the complexity of finish images, an algorithm derived from least-square circle fitting is applied for real-time track of finish areas in the image. For flaw feature extraction moment feature of connected components is adopted. After that a proposed algorithm based on feature statistical decision analysis is used for quality classification. It can deal with combination noise problem and obtain the satisfying accuracy with lower computational load. The proposed algorithms are proved to be efficient in automatic finish inspection.4. Base and sidewall cracks are regarded as critical defects for the recycled bottles adopted in beverage production. The sidewall axis is determined by scanning points of maximum grayscale grads on the line. And detection area of sidewall can be tracked for real time with high accuracy with the method of using symmetry analysis and probability statistics. The improved least-square fitting is used in base tracking. The bottles for any defects or presence of alien objects are checked using flaw feature extraction and statistical decision, and the ones with any defect are rejected and separated from the main stream. The proposed algorithms are proved to be efficient in the automatic base and sidewall inspection.5. The key technologies for the process of the empty bottle inspection system with the advantages of high-accuracy, integration, real-time and high-speed characteristics are summarized, which includes the proper configuration of hardware and software, the quick and efficient algorithm and the independent parallel performance of models.更多还原