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Scientia Silvae Sinicae ›› 2025, Vol. 61 ›› Issue (11): 150-159.doi: 10.11707/j.1001-7488.LYKX20250012

• Research papers • Previous Articles    

Online Detecting Method of Structural Lumber Knot Based on Deep Learning

Min Ji1,Rui Gao2,Xiaohuan Wang1,*(),Xingliang Diao1,Jiakai Han1,Yang Zhao1,Guofu Wang1,Wei Zhang1,*()   

  1. 1. Research Institute of Wood Industry, Chinese Academy of Forestry Beijing 100091
    2. Fujian Academy of Forestry Fuzhou 350012
  • Received:2025-01-07 Revised:2025-08-13 Online:2025-11-25 Published:2025-12-11
  • Contact: Xiaohuan Wang,Wei Zhang E-mail:wangxiaohuan@caf.ac.cn;wzhang@caf.ac.cn

Abstract:

Objective: To address the low efficiency and strong subjectivity of manual visual grading for structural sawn timber, this study selected Pinus densiflora structural sawn timber and developed a deep-learning-based online knot detection method, providing technical support for improving the automation and accuracy of structural sawn timber grading. Method: Based on the YOLO network, a knot-detection model was built that incorporates the efficient layer aggregation network (ELAN) and an image stitching, segmentation, and fusion scheme guided by SIFT features, strengthening the adaptability of the machine-vision defect-detection system to sawn-timber grading and other complex on-line vision tasks. Multi-scale prediction and loss-function minimization suppress background clutter and noise, enabling accurate classification and localization losses and thus raising knot-detection accuracy while optimizing task-specific performance. Result: In the industrial production application site, the test results showed that the identification and defect detection accuracy of knots on the surface of lumber is 90.97%, with a missed detection rate of 9.03%. The average detection accuracy of knot defect location X and Y was 86.29%, the average detection accuracy of knot defect size L and W was 85.95%, and the detection speed could reach 20–30 m·min?1, which meets the practical application of wooden product processing line. Conclusion: In this study, the deep learning method is suitable for lumber detection in practical application, reducing the subjectivity of manual inspection and improving the accuracy and efficiency of inspection. Machine vision detection technique promotes the innovation and development of wood grading technology, improves the quality of wood processing industry, and improves the technical level of wood structure construction industry.

Key words: Pinus densiflora structural lumber, machine vision knot inspection platform, deep learning, YOLO training model, efficient layer aggregation network

CLC Number: