Surface defect detection of steel strips based on improved YOLOv4

https://doi.org/10.1016/j.compeleceng.2022.108208Get rights and content

Highlights

Abstract

During the production and processing of steel strips, the production process and external factors lead to surface defects that negatively impact the strips’ integrity and functionality. However, traditional manual defect detection algorithms cannot meet modern accuracy requirements. Therefore, we propose a steel strip surface defect detection method based on the improved you-only-look-once version 4 (YOLOv4) algorithm. The attention mechanism is embedded in the backbone network structure, and the path aggregation network is modified into a customised receptive field block structure, which strengthens the feature extraction functionality of the network model. From the final experimental results, relative to the original YOLOv4 algorithm, the proposed algorithm's mean average precision values in the detection of four types of steel strip defects is improved by 3.87%, reaching 85.41%, thereby providing a new detection method for daily steel strip surface defects.

Introduction

Strip steel is an indispensable material for national construction and relates to the safety of urban infrastructure. During the production and processing of steel strips, owing to the influence of modern production technology and external factors, their surfaces may have various defects, such as plaques, inclusions, and scratches. These defects compromise their integrity and functionality, leading to construction accidents and endangering personal safety. Therefore, a speedy and accurate detection of surface defects in steel strips is critical. The traditional defect detection method involves random manual visual inspections. This method has the disadvantages of slow speed, low efficiency, high cost, poor detection environment, and potential safety hazards. Manual sampling is overly subjective, which leads to the low credibility of the results. Therefore, surface defect detection based on computer vision and deep learning is increasingly being used in modern production to solve these problems.

This paper is organised as follows. Section 2 presents the related work on computer vision and deep learning in the field of steel defect detection. In Section 3, information regarding the original you-only-look-once YOLO version 4 (YOLOv4) algorithm and the loss function is described. Detailed algorithm improvements are provided in Section 4. Section 5 presents the experimental results, and the conclusions are presented in Section 6.

Our contributions are as follows:

  • We propose a modified YOLOv4 algorithm for defect detection of industrial strip steel.

  • We design a convolutional block attention module (CBAM) for the backbone network and a receptive field block (RFB)-like structure replaces an enhance path aggregation network (PANet) to empower the information acquisition and feature extraction capability of the network.

  • The experimental results verify the superiority of the proposed algorithm.

Section snippets

Related work

As traditional defect detection methods have numerous drawbacks, computer vision-based methods are gradually gaining traction. Ref. [1] proposed a global adaptive percentile threshold method based on a gradient image. This method selectively segments the defect area and preserves defect features regardless of its size. Ref. [2] proposed a new algorithm based on wavelet anisotropic diffusion filtering. This method is effective at filtering out unwanted textural backgrounds in cold-rolled strips

YOLOV4 network structure

YOLOv4 is an updated and reinforced version of the YOLOv3 target-detection algorithm. The network structure is displayed in Fig. 1. First, the backbone network applies the cross-stage partial network (CSPnet) [16] to Darknet53, a 53-layer-deep CNN [17], and adds a CSPnet [16] structure to each group of resblock_body, continuously carrying out downsampling to obtain higher-level semantic information, which not only reduces the amount of computation but also enhances the gradient information.

A model's robustness improvement of YOLOv4

The improved YOLOv4 algorithm network architecture proposed in this study is marked in red boxes in Fig. 2, and the details are given in the subsequent two sections.

Experiment and result analysis

In this section, we describe the dataset, evaluation indicators, comparison objects, and methods, and finally dissect the experimental results to confirm the practicality of the improved model.

Conclusions

In response to the multiple difficulties faced in the task of steel strip defect detection, this study proposed a detection algorithm based on an improved YOLOv4. The value of this algorithm lies in the following:

  • Its YOLOv4 backbone network is embedded with CBAM.

  • Its YOLOv4 feature extraction network SPP module is improved to the customised RFB structure to deepen the network.

  • Among the four defect types in the NEU-DET dataset, our model achieved a 3.87% improvement in mAP over the original

CRediT authorship contribution statement

Mengjiao Li: Conceptualization, Methodology, Software, Investigation, Formal analysis, Writing – original draft. Hao Wang: Data curation, Writing – original draft. Zhibo Wan: Funding acquisition, Supervision, Writing – review & editing.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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