高架草莓的果实识别与果梗分割

    Fruit recognition and stem segmentation of the elevated planting of strawberries

    • 摘要: 在高架栽培环境下,精准识别草莓果实并分割果梗对提升草莓采摘机器人的作业精度和效率至关重要。该研究在原YOLOv5s模型中引入自注意力机制,提出了一种改进的YOLOv5s模型(ATCSP-YOLOv5s)用于高架草莓的果实识别,并通过YOLOv5s-seg模型实现了果梗的有效分割。试验结果显示,ATCSP-YOLOv5s模型的精确率、召回率和平均精度值分别为97.24%、94.07%、95.59%,较原始网络分别提升了4.96、7.13、4.53个百分点;检测速度为17.3帧/s。此外,YOLOv5s-seg果梗分割模型的精确率、召回率和平均精度值分别为82.74%、82.01%和80.67%。使用ATCSP-YOLOv5s模型和YOLOv5s-seg模型分别对晴天顺光、晴天逆光和阴天条件下的草莓图像进行检测,结果表明,ATCSP-YOLOv5s模型在3种条件下识别草莓果实的平均精度值为95.71%、95.34%、95.56%,较原始网络提升4.48、4.60、4.50个百分点。YOLOv5s-seg模型在3种条件下分割草莓果梗的平均精度值为82.31%、81.53%、82.04%。该研究为草莓采摘机器人的自动化作业提供了理论和技术支持。

       

      Abstract: Accuracy and efficiency of strawberry picking depend mainly on the recognition of strawberry fruit and segmentation of fruit stem in the elevated cultivation environment. In this study, an improved YOLOv5s recognition (ATCSP-YOLOv5s) was proposed for the elevated strawberry fruits under elevated cultivation environment, while a YOLOV5s-seg segmentation model was applied to detect and segment fruit stems. The detection accuracy of the recognition model was attributed to the improved backbone network of YOLOv5s. The self-attention mechanism was introduced to establish the self-attention cross-stage feature fusion network. This innovative structure was focused on the correlation of inherent features without the dependence on the external cues, thus improving the ability of the network to extract target features. The better performance was achieved to identify the small targets, blocked or overlapping strawberry fruits. The detection and segmentation of strawberry stem included the backbone network, feature fusion network, recognition head, and segmentation head of segmentation module. The mask information of strawberry and stem was captured at the same time. The interest region was determined to contain the target fruit stem. Then, the accurate segmentation of strawberry stem was effectively realized in the overhead cultivation using linear combination of recognition and segmentation. The experimental results showed that the precision (P), recall (R), and mean average precision (mAP) of strawberry fruit recognition by ATCSP-YOLOv5s model were 97.24%, 94.07%, and 95.59%, respectively. The detection speed was 17.3 frames per second. The P, R and mAP values of strawberry frontlight processing on sunny days by ATCSP-YOLOv5s were 97.89%, 95.16% and 95.71%, respectively, which were 3.06, 6.22 and 4.48 percentage points higher than those by YOLOv5s. The P, R and mAP values of strawberry backlight processing on sunny days were 96.53%, 93.97% and 95.34%, respectively, which were 3.26, 7.43 and 4.6 percentage points higher than those of YOLOv5s. The P, R and mAP values of strawberry image processing on cloudy days were 96.93%, 94.88% and 95.56%, respectively, which were 2.30, 7.01 and 4.50 percentage points higher than those of YOLOv5s. The performance of ATCSP-YOLOv5s recognition model was compared with that of Faster RCNN, YOLOv4, YOLOv5s, YOLOv6s, YOLOv7, and YOLOv8. The experimental results showed that the P values of ATCSP-YOLOv5s recognition model was 6.73, 5.92, 4.96, 4.77, 3.35 and 3.43 percentage points higher than Faster RCNN, YOLOv4, YOLOv5s, YOLOv6s, YOLOv7 and YOLOv8, respectively. The R values were higher by 11.68, 4.75, 7.13, 3.82, 3.76 and 3.01 percentage points, respectively. The mAP values were 8.64, 7.03, 4.53, 4.27, 4.31, and 3.55 percentage points higher, indicating the better recognition performance. In addition, the mAP of the ATCSP-YOLOv5s recognition model was above 90%, when detecting strawberry images under different lighting conditions, indicating the better robustness. The P, R and mAP values of all images that processed by the YOLOv5s-seg segmentation model were 82.74%, 82.01%, and 80.67%, respectively. The P values of strawberry images that processed by the YOLOv5s-seg segmentation model on sunny frontlight, sunny backlight, and cloudy days were 85.32%, 81.26%, and 81.89%, respectively. The R values were 83.65%, 82.03% and 83.20%, respectively, while the mAP values were 82.31%, 81.53% and 82.04%, respectively, and the segmentation accuracy was 98.29%, indicating the better segmentation accuracy and universality. The comprehensive experiment showed that the ATCSP-YOLOv5s recognition and YOLOv5s-seg segmentation model can be expected to rapidly and accurately identify the strawberry fruit, and then segment the target fruit stem. This finding can provide the theoretical and technical support for the automatic operation of strawberry picking robot, particularly on the target sensing and efficient picking of strawberry picking robots.

       

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