边缘感知增强的煤矿井下视觉SLAM方法

An edge aware enhanced visual SLAM method for underground coal mines

  • 摘要: 【目的】 煤矿井下普遍存在低照度、弱纹理和结构化的特征退化场景,导致视觉SLAM(VisualSimultaneous Localization and Mapping)系统面临有效特征不足或误匹配率高的问题,严重制约了其定位的准确性和鲁棒性。【方法】 提出一种基于边缘感知增强的视觉SLAM方法。首先,构建了边缘感知约束的低光图像增强模块。通过自适应尺度的梯度域引导滤波器优化Retinex算法,以获得纹理清晰光照均匀的图像,从而显著提升了在低光照和不均匀光照条件下特征提取性能。其次,在视觉里程计中构建了边缘感知增强的特征提取和匹配模块,通过点线特征融合策略有效增强了弱纹理和结构化场景中特征的可检测性和匹配准确性。具体使用边缘绘制线特征提取算法(Edge Drawing Lines,EDLines)提取线特征,定向FAST和旋转BRIEF点特征提取算法(Oriented FAST and Rotated BRIEF,ORB)提取点特征,并利用基于网格运动统计(Grid-based Motion Statistics,GMS)和比值测试匹配算法进行精确匹配。最后,将该方法与ORBSLAM2、ORB-SLAm3在TUM数据集和煤矿井下实景数据集上进行了全面实验验证,涵盖图像增强、特征匹配和定位等多个环节。【结果和结论】 结果表明:(1)在TUM数据集上的测试结果显示,所提方法与ORB-SLAM2相比,绝对轨迹误差、相对轨迹误差的均方根误差分别降低了4%~38.46%、8.62%~50%;与ORB-SLAm3相比,绝对轨迹误差、相对轨迹误差的均方根误差分别降低了0%~61.68%、3.63%~47.05%;(2)在煤矿井下实景实验中,所提方法的定位轨迹更接近于相机运动参考轨迹;(3)有效提高了视觉SLAM在煤矿井下特征退化场景中的准确性和鲁棒性,为视觉SLAM技术在煤矿井下的应用提供了技术解决方案。研究面向井下特征退化场景的视觉SLAM方法,对于推动煤矿井下移动式装备机器人化具有重要意义。

     

    Abstract: Objective Low illumination, weak textures, and degraded structured features are commonly found in underground coal mines, resulting in insufficient effective features or high mismatch rates in Visual SLAM (Simultaneous Localization and Mapping) systems. This severely limits the accuracy and robustness of localization. Methods An edge aware enhancement based Visual SLAM method is proposed. Initially, an edge aware constrained low light image enhancement module is constructed. The Retinex algorithm is optimized with an adaptive scale gradient domain guided filter to obtain images with clear textures and uniform illumination, sensibly improving feature extraction performance under low and uneven lighting conditions. Subsequently, an edge aware enhanced feature extraction and matching module is built in the visual odometry. It enhances feature detectability and matching accuracy in weakly textured and structured environments. The point and line features are extracted using ORB(Oriented FAST and Rotated BRIEF) and EDLines(Edge Drawing Lines) algorithms, with precise matching achieved through GMS(Grid-based Motion Statistics) and ratio test strategies. Finally, the method is evaluated on the TUM dataset and an underground coal mine real world dataset, in comparison with ORB-SLAM2 and ORB-SLAm3, covering image enhancement, feature matching, and localization. Results and Conclusions The results show that (1) on the TUM dataset, the proposed method reduces the root mean square error of absolute and relative trajectory errors by 4%~38.46% and 8.62%~50% compared to ORB-SLAM2, and by 0%~61.68% and 3.63%~47.05% compared to ORB-SLAm3, respectively; (2) in underground coal mine real world dataset experiments, the localization trajectory of the proposed method is closer to the camera motion reference trajectory; (3) the proposed method effectively improves the accuracy and robustness of Visual SLAM in feature degradation scenes in underground coal mines, providing a technical solution for the application of Visual SLAM technology in coal mines. Research on Visual SLAM methods for degraded feature scenarios in underground environments is important for advancing the robotization of mobile equipment in coal mines.

     

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