Research Development and Prospect of Solar Cells Surface Defects Detection Based on Machine Vision
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摘要: 鉴于基于机器视觉的太阳能电池片表面缺陷检测方法具有操作简便、检测精度高的优势,对此类方法所涉及的各个环节进行了综述. 首先,对太阳能电池片表面的各种成像方式和常见缺陷类型进行了归纳总结;其次,对现有的检测方法按照数学建模思路的不同进行了分类介绍和对比分析;最后,对内容进行了小结并对太阳能电池片表面缺陷检测方法的后续研究进行了展望. 可以看出:基于机器视觉的太阳能电池片表面缺陷检测方法已经取得了较大的发展,但在特征提取算法设计方面仍有改进空间,如基于深度神经网络的特征提取算法.Abstract: Considering the advantages of simple operation and high detecting accuracy, all aspects involved in solar cell surface defect detection methods based on machine vision were reviewed in this paper. First of all, the various imaging techniques and common defect types of solar cells surface were summarized. Secondly, the existing detection methods were introduced and compared with each other according to the different idea of mathematical modeling. Finally, a brief summary of this article and perspective of future research are presented. It can be concluded that the solar cell surface defect detection methods based on machine vision have made great progress. However, there is still room for improvement in algorithm design of feature extraction, such as feature extraction algorithm based on deep neural networks.
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Key words:
- solar cell /
- machine vision /
- surface defect /
- imaging
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图 2 近红外成像各类缺陷示例[31]
Figure 2. Illustrations of various defects based on near infrared imaging
表 1 太阳能电池片表面常见缺陷[36]
Table 1. Common defects of solar cell surface
缺陷类别 缺陷名称 视觉特点 成因 形状缺陷 缺角、破损、裂纹、断栅 与标准片相比,形状上有缺损或者多余部分 误切割、碰撞、生产失误 颜色缺陷 颜色异常、不均匀,边角区域颜色异常 与标准片相比,大部分区域存在着颜色异常或者不均匀 镀膜时化学反应不均匀 纹理缺陷 斑点、指纹、轮印 与标准片相比,存在过亮或者过暗区域,有斑点状或指纹、轮印 人工操作不当、机器压力过大 表 2 各类检测方法的比较
Table 2. Comparison of various detection methods
类型 梯度特征的检测方法 聚类的检测方法 频域分析的检测方法 矩阵分解的检测方法 机器学习的检测方法 摘要 根据电池片的裂纹、断栅处和背景有明显亮度差异的特点,以梯度特征为核心进行缺陷检测 采用各种聚类算法将电池片表面分成缺陷集合和非缺陷集合,然后采用图像分割得到检测结果 将图像从空间域变换到频率域,通过设定合适的频率值做带通(带阻)滤波,实现预定目标的凸显(移出) 将电池片表面图像数据视作矩阵,通过某些矩阵分解算法分解出仅包含电池片缺陷区域的矩阵,将该矩阵适当处理后作为检测结果 分别收集无缺陷和有缺陷的图像作为训练样本,选择合适的机器学习算法学习分类模型,将测试图像代入该模型即得检测结果 特点 此类方法对裂纹和断栅等亮度对比度较强的缺陷类型检测效果较好 此类方法对不同类型的缺陷有较强的识别能力,但是聚类算法某些关键参数需要手工设定 此类方法复杂度低,实时性较好,对于检测斑点、断栅、裂纹有较好的效果 此类方法适用范围广,算法简洁有效,尤其适合对微小缺陷的检测 此类方法对训练样本中已收集的常见缺陷类型能够较好识别 -
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