基于改进Faster RCNN模型的冬枣缺陷检测方法

    Detecting winter jujube defects using improved Faster RCNN model

    • 摘要: 为了解决冬枣分选工作准确率低、速度慢、人工成本高昂等问题,该研究提出了一种基于改进Faster RCNN模型的冬枣外观缺陷识别方法。首先,使用Resnet50替换原有的VGG16特征提取网络,并在Resnet50中添加SE模块,提高模型的特征提取能力;其次,融入特征金字塔(feature pyramid network FPN)网络,对不同尺度的特征信息充分提取;最后,将原始的NMS算法用改进的Soft-NMS算法替换,改善被检测图像中对缺陷检测目标的误删问题,进一步提高对冬枣缺陷识别的准确率,试验结果表明:改进的Faster RCNN模型对冬枣缺陷检测平均精度均值(mean average precision, mAP)为91.60%,检测速度为17.5帧/s,mAP比SSD、YOLOv3、YOLOv5分别高14个百分点、11.32个百分点、5.94个百分点,将改进的Faster RCNN网络模型部署在冬枣检测平台上对不同品质的冬枣进行分选,其对优质果、伤果、裂果、虫果、病果的识别准确率分别为94.71%、96.99%、99.06%、93.82%、99.05%。改进的Faster RCNN网络模型能有效的对冬枣外观做出准确、快速的判断,降低冬枣检测过程中的误检率。

       

      Abstract: Sorting winter jujube is one of the most essential tasks after harvesting. An effective sorting and grading can be used to enhance the brand recognition of winter jujubes. The current sorting task of winter jujube work still relies mainly on manual labor. Alternatively, large-scale sorting equipment cannot be afforded for the individual jujube farmers, due to its high price. Fortunately, deep learning has been widely applied in the field of agricultural product detection. It is also expected for the intelligent and automatic sorting of winter jujubes. However, there is still a research gap in the market for the small-scale devices and algorithms suitable for winter jujubes sorting. Furthermore, the existing equipment in winter jujube sorting is also confined to the low accuracy, slow speed, and high cost. In this study, an improved Faster R-CNN model was proposed to identify the external defects of winter jujubes for the small-scale sorting. Firstly, the original VGG16 feature extraction network was replaced with the ResNet50. An SE module was then added into ResNet50 to explicitly model the interdependencies among channels, where the network was adaptively recalibrated the feature responses of each channel. As such, the network was used to focus more on the useful features while suppressing irrelevant ones, thereby enhancing the representation capability of features. Secondly, the feature pyramid network (FPN) was integrated to fully extract feature information at different scales. Finally, the original non-maximum suppression (NMS) algorithm was replaced with the improved Soft-NMS algorithm to reduce the issue on the mistakenly deleting targets of defect detection in the detected images, further improving the accuracy of winter jujube defect identification. The experimental results show that the improved Faster R-CNN model shared a mean average precision (mAP) of 91.60% for the winter jujube defect detection, with a detection speed of 17.5 frames per second. The mAP was 14 percentage points higher than SSD, 11.32 percentage points higher than YOLO v3, and 5.94 percentage points higher than YOLO v5. When the improved Faster R-CNN network model was deployed on the detection platform to sort the winter jujubes of different qualities, the recognition accuracies for Good fruit, Mechanical injury fruit, Cracking or splitting fruit, Insect fruit, and Disease fruit were 94.71%, 96.99%, 99.06%, 93.82%, and 99.05%, respectively. Although the detection time of two-stage object detection networks was longer than the rest, the impact of detection speed was neglected with the support of high-performance computers. The improved Faster R-CNN network model can effectively and rapidly identify the appearance of winter jujubes, thus reducing the false detection rate in the winter jujube detection. The research finding can provide the promising ideas and theoretical support to the mechanization of the winter jujube industry.

       

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