【作者】 方迪生；

【导师】 闵庆凯； 王滨； 张文明；

【作者基本信息】 沈阳大学 ， 材料加工工程， 2012， 硕士

【摘要】 窄间隙埋弧焊施焊的过程中要求电弧始终保持对中,所以为了满足这个要求,引入焊缝自动跟踪系统。目前的焊缝自动跟踪系统有很多种,分别基于不同的传感器,但是视觉传感器较其他传感器有明显的优势,所以开发基于视觉传感器的焊缝跟踪系统很有必要。图像采集系统是基于视觉传感器焊缝跟踪系统的重要组成,它的功能是接收相机输入的图像数据,进行缓冲和预处理,最后有效的输出到计算机中。而计算机做进一步的图像处理,反馈出电弧对中信号给机械控制部分,从而实现焊缝自动跟踪。可以说图像采集的精确性、清晰度和速度等是焊缝自动跟踪的关键。图像采集系统主要由两个大部分组成,分别为光路结构和图像采集卡。光源和视觉传感器以一定角度、距离安装构成光路结构。图像采集卡根据实际应用情况选择了完整开发设计。整个系统的设计重点在于图像采集卡,由于本图像采集卡专用于窄间隙埋弧焊,所以设计中主要以窄间隙埋弧焊焊缝及焊接过程特点为依据。图像采集卡以FPGA为逻辑控制和图像预处理算法实现的核心器件,不仅使整个设计具有很高的灵活性,而且使电路高效简洁。在与相机的连接问题上,采用市场上广泛应用的camera link作为图像采集卡的输入接口,提高了采集卡的通用性、数据传输速率和抗干扰能力。采用PCI总线作为图像采集卡的输出接口,实现图像采集卡与计算机之间的数据传输,达到数据传输的高速度和高精度。第一部分为图像采集系统的光路结构设计,详细论述了光源的选择方案和实际安装,以及它和视觉传感器实现焊缝图像采集的原理。第二部分为图像采集卡的设计,也是本课题的工作重点,包括图像采集卡的硬件电路设计和软件编程设计。最后介绍了图像采集卡在计算机上的测试情况,而且根据焊缝图像特征,对图像预处理方法做了相关研究。对于焊接过程中的弧光、飞溅、烟尘等的影响,分别使用了图像增强、平滑滤波和二值化等预处理方法,最终得到了焊缝特征明显、数据量小的焊缝图像。更多还原

【Abstract】 It is required that the welding arc must be kept in the center during narrow-gap SAW, In order to meet this demand , the automatic welding beam tracking system is introduced . Currently, there are various types of automatic welding beam tracking system based on different sensors , but one type of them is highly superior ,which is the optical sensor based automatic welding tracking system . Image capture system is a important component of optical sensor based automatic welding tracking system, which function is to receive the image data from the camera, after pre-processing these data, transfer them to the computer ultimately. After the computer does the post-image-processing and feedbacks the magnitude of welding arc deviation to the mechanical control system, the automatic tracking achieves. so correspondingly we can say that the accuracy, definition and speed of the image capture system is crucial to the welding beam tracking .The image capture system mainly consists of two parts, which are optical structure and the image capture card. The optical structure is taking shape by installing the light source and optical sensor in a specific way. The image capture card is designed according to the particular applying circumstance. The key design of the whole image capture system is on image capture, because the image capture card is specifically for narrow gap SAW, the design mainly relies on the characteristics of narrow gap welding beam and welding circumstance . The image capture card choses FPGA to be the core processor for logic control and image pre-processing materialization, which not only makes the design highly flexible, but makes the circuit efficiently brief. For connecting the digital camera, adopts the extensively used camera link to be input of the image capture card, which improves the commonality, data transport speed and anti-interference ability. Adopts the PCI bus to be the output of the image capture card, to connect the card and the computer, which obtain the high speed and accuracy of data transportation. First section is the optical structure design of image capture system. This section explicitly illustrates the way of choosing and installing the light source, and the way of how it can implement the welding beam image capture with optical sensors. The second section is the design of image capture card, and it is the key work of this paper, which includes the hardware and the software design of each. At last we illustrate the testing of the image capture card on computer, and according to the characteristic of welding beam, we study the method of image pre-processing. Due to the impact of welding arc、welding splash、welding fume in the welding process, we use the image enhancement、smoothing filtering, thresholding to process the image, finally acquired the welding beam image with conspicuous characteristics and small data volume.更多还原