Research on the Detection Method of Coal Mine Roadway Bolt Mesh Based on Improved YOLOv7

Abstract

Aiming at the environment of low illumination, high dust, and heavy water fog in coal mine driving face and the problems of occlusion, coincidence, and irregularity of bolt mesh laid on coal wall, a YOLOv7 bolt mesh-detection algorithm combining the image enhancement and convolutional block attention module is proposed. First, the image brightness is enhanced by a hyperbolic mapping transform-based image enhancement algorithm, and the image is defogged by a dark channel-based image defogging algorithm. Second, by introducing a convolutional block attention model in the YOLOv7 detection network, the significance of bolt mesh targets in the image is improved, and its feature expression ability in the detection network is enhanced. Meanwhile, the original activation function ReLU in the convolutional layer Conv of the YOLOv7 network is replaced by LeakyReLU so that the activation function has stronger nonlinear expression capability, which enhances the feature extraction performance of the network and thus improves the detection accuracy. Finally, the training and testing samples were prepared using the actual video of the drilling and bolting operation, and the proposed algorithm is compared with five classical target detection algorithms. The experimental results show that the proposed algorithm can be better applied to the low illumination, high dust environment, and irregular shape on the detection accuracy of coal mine roadway bolt mesh, and the average detection accuracy of the image can reach 95.4% with an average detection time of 0.0392 s.

Study on the Recognition of Coal Miners’ Unsafe Behavior and Status in the Hoist Cage Based on Machine Vision

“…Although this approach's detection accuracy is good, its speed is slow. Therefore, regression-based one-stage detectors represented by the You Only Look Once (YOLO) series [16][17][18][19][20][21][22][23] and single shot multi-box detector (SSD) [24], known for their high detection accuracy and speed, were used to identify coal mine miners' unsafe behaviors. In order to identify whether security equipment is being worn, the SSD model was improved by replacing the feature extraction network visual geometry group (VGG- 16) with MobileNet [25].…”