激光拼焊焊缝质量在线检测技术研究

激光拼焊作为一种新的高质量焊接技术，已经广泛应用于汽车，航空、造船等领域，对提高我国装备制造水平有重要意义。激光拼焊过程中由于焊接装置与焊接工艺的一些时变因素，导致焊接质量存在一定波动，因此，必须对焊缝进行在线实时质量检测，这不仅可以保证焊接质量，而且有助于实现焊接的自动化。目前，国外成熟的激光拼焊系统中，焊缝质量实时检测技术已经成为实现激光拼焊自动化的关键部分。但该项技术国内目前仍处于研究阶段。因此，研制应用于激光拼焊的焊缝质量实时检测系统，实现焊接过程的自动化在学术理论性及工程应用性上具有重要研究意义。本文以激光拼焊为背景，针对激光焊接焊缝质量检测中存在的科学问题和实际应用需求，参考了国外先进的焊缝质量检测系统，应用机器视觉原理对焊缝质量检测方法进行了研究。 本文首先介绍了基于结构光视觉检测原理建立的焊缝质量检测系统。其次重点研究了焊缝质量检测系统的图像处理算法。图像处理算法是整个检测系统的核心内容，其处理的速度与精度直接影响到系统的实时性与准确性。本文依据ISO13919-1 B级焊缝质量标准设计了基于结构光的焊缝图像处理算法。算法主要分三步：首先准确提取结构光光纹中心线，其次提取光纹中心线特征点，最后，根据光纹的几何形状以及所提取的特征点，计算焊缝缺陷参数。第二部分系统介绍了结构光视觉传感器的标定原理及方法，针对激光拼焊焊缝质量检测应用需求，研究了焊缝质量检测视觉传感器直接标定方法。并设计了标定方法的具体实现，通过在局部区域建立光平面到像平面之间的线性函数关系，像平面中的任意一个像点对应的物理坐标，可以通过线性插值算出。实验结果表明，标定精度可以满足激光拼焊质量检测系统的精度要求，且便于工程实现。第三部分针对激光拼焊质量检测需求，进行了焊缝质量检测系统的软、硬件设计及实现。重点研究了软件实现中的一些关键问题，如Windows实现检测系统的方法，进程、线程的优先级，三维重建等。最后在该检测系统实验平台上进行了图像处理算法的精度与速度的验证，实验结果表明图像算法结果满足系统要求。最后，本文对所做的研究工作进行了总结，并对今后的工作进行了展望。

智能相机在激光焊缝跟踪检测系统中的应用研究

本文以中国科学院知识创新工程重要方向项目“全自动激光拼焊成套装备关键技术研究与示范应用”及沈阳市科技攻关项目“激光视觉焊缝自动跟踪与质量检测系统”为依托，针对激光焊接这个难点问题，在广泛调研国内外研究现状的基础上，研究开发了一套激光视觉焊缝跟踪检测原理样机。本文主要包括以下四方面的工作：1焊缝跟踪系统的系统结构搭建；2图像处理方法研究；3图像处理方法在FPGA中的实现；4基于工业机器人的激光焊接实验 及结果分析。具体工作如下： 本文首先论述了应用于焊缝跟踪的线结构光视觉传感器检测原理，建立了激光焊缝跟踪检测系统实验平台。该平台由图像采集与处理模块、上位机系统、DSP控制器、伺服电机驱动器、伺服电机等五部分组成。 激光拼焊焊缝跟踪图像的处理方法是关键技术之一，直接影响系统的实时性，根据激光拼焊焊缝跟踪图像的特点设计了相应的图像处理算法，分析研究了基于数学形态学的焊缝跟踪结构光条纹图像增强算法，并根据本课题的特点提出了一种基于模板的边缘提取方法，能简洁快速地提取出单像素边缘，然后研究了结构光中心线提取算法以及焊缝特征点识别算法，最后通过仿真实验验证了该图像处理流程的有效性。 论文的重点在于图像处理方法在智能相机中的实时实现。跟踪系统对图像处理的实时性要求很高，传统的处理方法主要是在DSP中以软件编程的方式实现，速度难以进一步提高，本课题中通过在智能相机中的FPGA中构建一个SOPC系统，将基于硬件描述语言VHDL完成的图像预处理模块和基于Xilinx公司的microblaze软核的特征点提取模块集成在单片芯片上，实现了激光条纹特征点的实时提取，系统具有高度的灵活性与出色的功能。 最后对搭建的跟踪系统平台进行了实验研究，用实验验证了焊缝跟踪系统的性能，保证了该套系统能够满足实时跟踪的要求，可以达到预期的设计目标。

Improving Nucleation in the Fabrication of High-Quality 3D Macro-Porous Copper Film through The Surface-Modification of A Polystyrene Colloid-Assembled Template

A new approach is developed to the fabrication of high-quality three-dimensional macro-porous copper films. A highly-ordered macroporous copper film is successfully produced on a polystyrene sphere (PS) template that has been modified by sodium dodecyl sulfate (SDS). It is shown that this procedure can change a hydrophobic surface of PS template into a hydrophilic surface. The present study is devoted to the influence of the electrolyte solution transport on the nucleation process. It is demonstrated that the permeability of the electrolyte solution in the nanochannels of the PS template plays an important role in the chemical electrodeposition of high-quality macroporous copper film. The permeability is drastically enhanced in our experiment through the surface modi. cation of the PS templates. The method could be used to homogeneously produce a large number of nucleations on a substrate, which is a key factor for the fabrication of the high-quality macroporous copper film.

Pressure Controlled Self-Assembly of High Quality Three-Dimensional Colloidal Photonic Crystals

A concise pressure controlled isothermal heating vertical deposition (PCIHVD) method is developed, which provides an optimal growing condition with better stability and reproducibility for fabricating photonic crystals (PCs) without the limitation of colloidal sphere materials and sizes. High quality PCs are fabricated with PCIHVD from polystyrene spheres with diameters ranging from 200 nm to 1 mu m. The deep photonic band gap and steep photonic band edge of the samples are most favorable for realizing ultrafast optical devices, photonic chips, and communications. This method makes a meaningful advance in the quality and diversity of PCs and greatly promotes their wide applications.

On-line observation of interlaminar damage by ultrasonic inspection

This paper explores an on-line experimental method to highlight the process of internal damage development in composites by taking advantage of ultrasonic inspection. A loading device, which can work together with an ultrasonic inspection system, was designed, and the interlaminar shear damage of a double-sided grooved specimen of composite was examined on-line with the system. A full view of the progressive internal interlaminar damage, seen only with difficulty by common inspection methods, was successfully achieved.

The Key Factors In Fabrication Of High-Quality Ordered Macroporous Copper Film

The template-directed fabrication of highly-ordered porous film is of significant importance in implementation of the photonic band gap structure. The paper reports a simple and effective method to improve the electrodeposition of metal porous film by utilizing highly-ordered polystyrene spheres (PSs) template. By surface-modification method, the hydrophobic property of the PSs template surfaces was changed into hydrophilic one. It was demonstrated that the surface modi. cation process enhanced the permeability of the electrolyte solution in the nanometer-sized voids of the colloidal template. The homogeneously deposited copper film with the highly-ordered voids in size of less than 500 nm was successfully obtained. In addition, it was found that large defects, such as microcracks in the template, strongly influenced the macroporous films quality. An obvious preferential growth in the cracked area was observed. (C) 2008 Elsevier B. V. All rights reserved.