中文摘要：

针对水下焊接图像噪声大、清晰度差的特殊情况，设计并研制成功一套药芯焊丝水下焊接的视觉传感焊缝自动跟踪系统。该系统由视觉传感、图像预处理及偏差识别系统，控制系统和执行机构等组成。采用小波多尺度变换进行水下焊缝图像边缘提取，结果保留大多数的细节，得到有利于焊缝位置特征提取的预处理图像，在一种基于二值图像的焊缝中心位置识别算法计算后，得出焊缝偏差。在理论分析视觉传感焊缝自动跟踪系统模型的基础上，设计满足跟踪精度要求的规则自调整模糊算法。对影响跟踪系统精度的因素进行分析，并采用相应的措施以提高系统的精度。通过药芯焊丝湿法水下焊接焊缝自动跟踪试验表明，采用规则自调整模糊控制能够达到较高的焊缝跟踪精度。在斜线、折线和曲线三种不同形状待焊焊缝的跟踪试验中，系统都能满足药芯焊丝水下自动焊接的要求。经过改进微型排水罩，进行微型排水罩局部干法药芯焊丝水下焊接焊缝跟踪试验，采用规则自调整模糊控制，不仅得到满意的焊缝跟踪效果，还改善焊缝成形质量。

英文摘要：

To track seam automatically during underwater flux-cored arc welding（UFCAW）, a vision-based seam tracking system has been studied. This seam tracking system consists of a vision sensing system, an image processing and seam recognizing system, a control system and executive unit. The edge of the weld line is precisely detected by a wavelet transform method. The seam position error is calculated by a seam position recognition algorithm based on the binary image. Based on the theoretic analyze of the structure model of the vision-based seam tracking system, a control rule self-adjust fuzzy controller is designed. The factors of decreasing the precision of the seam tracking system are analysised, and some measures are adopted to improve the tracking precision. The tracking experiments results of the UFCAW confirm that the control rule self-adjust fuzzy controller meet the demand of the tracking precision. In the tracking trials of sidelong, reflex and curve weld line, the system can all meet the demand of the tracking precision. With the improved mini drain water cap, the tracking experiments of the underwater local dry welding are carried. The results indicate that this process can not only welding quality but also satisfy the meet the demand of improve tracking results.