Light-YOLOv3: fast method for detecting green mangoes in complex scenes using picking robots

摘要

When a robot picks green fruit under natural light, the color of the fruit is similar to the background; uneven lighting and fruit and leaf occlusion often affect the performance of the detection method. We take green mangoes as an experimental object. A lightweight green mangoes detection method based on YOLOv3 is proposed here. To improve the detection speed of the method, we first combine the color, texture, and shape features of green mango to design a lightweight network unit to replace the residual units in YOLOv3. Second, the improved Multiscale context aggregation (MSCA) module is used to concatenate multilayer features and make predictions, solving the problem of insufficient position information and semantic information on the prediction feature map in YOLOv3; this approach effectively improves the detection effect for the green mangoes. To address the overlap of green mangoes, soft non-maximum suppression (Soft-NMS) is used to replace non-maximum suppression (NMS), thereby reducing the missing of predicted boxes due to green mango overlaps. Finally, an auxiliary inspection green mango image enhancement algorithm (CLAHE-Mango) is proposed, is suitable for low-brightness detection environments and improves the accuracy of the green mango detection method. The experimental results show that the F1% of Light-YOLOv3 in the test set is 97.7%. To verify the performance of Light-YOLOv3 under the embedded platform, we embed one-stage methods into the Adreno 640 and Mali-G76 platforms. Compared with YOLOv3, the F1% of Light-YOLOv3 is increased by 4.5%, and the running speed is increased by 5 times, which can meet the real-time running requirements for picking robots. Through three sets of comparative experiments, we could determine that our method has the best detection results in terms of dense, backlit, direct light, night, long distance, and special angle scenes under complex lighting.