用特征散射方向图预估电大平面阵的散射

利用平面照射波在无限大周期阵列上感应电流的周期特性,对无限阵列格林函数加窗的方法得到了有限阵列的格林函数,从而将电大有限阵列的分析缩减到单个的阵元上。进而由矩量法得到单个阵元上的电流分布和散射场,并定义为单元的特征散射方向图。仿照阵列综合理论,整个阵列的散射归结为特征散射方向图和阵因子的乘积,极大的简化了电大有限阵列的散射分析,并通过算例验证了该方法的有效性。

Face mask detection algorithm based on HSV+HOG features and SVM

To automatically detecting whether a person is wearing mask properly,we propose a face mask detection algorithm based on hue-saturation-value(HSV)+histogram of oriented gradient(HOG)features and support vector machines(SVM).Firstly,human face and five feature points are detected with RetinaFace face detection algorithm.The feature points are used to locate to mouth and nose region,and HSV+HOG features of this region are extracted and input to SVM for training to realize detection of wearing masks or not.Secondly,RetinaFace is used to locate to nasal tip area of face,and YCrCb elliptical skin tone model is used to detect the exposure of skin in the nasal tip area,and the optimal classification threshold can be found to determine whether the wear is properly according to experimental results.Experiments show that the accuracy of detecting whether mask is worn can reach 97.9%,and the accuracy of detecting whether mask is worn correctly can reach 87.55%,which verifies the feasibility of the algorithm.

基于视觉特征的厚板机器人焊接焊缝轮廓的有效提取

基于结构光的主动视觉传感技术是用于厚板机器人自动焊接中检测焊缝信息的一种有效途径。针对焊接过程中采集的焊缝图像包含或不包含电弧区域的两种情形,提出了一种基于视觉特征的适用于典型接头的激光条纹提取的通用算法。该算法利用Gabor滤波生成方向特征图,阈值分割后利用最近邻聚类算法对激光条纹和干扰数据进行聚类,根据聚类结果获得各类数据点在图像中的空间跨度,且只保留跨度值大于平均跨度的类,实现激光条纹的粗略提取;在从粗略提取结果中获取首个激光条纹分段的前提下,利用后续待识别的类与前一次已提取的激光条纹分段的欧式距离和类的自身跨度,设计了一个能提取激光条纹后续分段的竞争策略,从而实现激光条纹主体轮廓的准确提取;根据激光条纹视觉投射特点,设计了一个提取主体轮廓各分段之间的激光条纹细节的有效规则,实现激光条纹细节的提取。利用厚板T形接头和对接接头焊接中采集的焊缝图像验证了文中激光条纹提取算法的有效性,为厚板机器人自主焊接智能系统面向多种接头焊接应用的集成提供了可能。