Purpose

This paper aims to enable the unmanned aerial vehicles to inspect the surface condition of wind turbine in close range when the global positioning system signal is not reliable, and further improve its intelligence. So a visual-inertial odometry with point and line features is developed.

Design/methodology/approach

Visual front-end combining point and line features, as well as its purification strategies, are first presented to improve the robustness of feature tracking in low-textured scene and rapidity of segment detector. Additionally, the inertial measurement is integrated between keyframes as constrain to reduce tracking error existed in visual-only system. Second, the graph-based visual-inertial back-end is constructed. To parameterize line features effectively, the infinite line representation not sensitive to outdoor light is employed, in which Plücker and Cayley are selected for line re-projection and nonlinear optimization. Furthermore, Jacobians of the line re-projection errors are analytically derived for better accuracy.

Findings

Experiments are performed in various scenes of the wind farm. The results demonstrate that the tight-coupled visual-inertial odometry with point and line features is more precise on all the samples than conventional algorithms in complex wind farm environments. Additionally, the constructed line feature map can be used in the following research for autonomous navigation.

Originality/value

The proposed visual-inertial odometry works robustly in strong electromagnetic interference, low-textured and illumination-change wind farm.

中文翻译：

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用于叶片检查无人机的具有点和线特征的鲁棒视觉惯性里程计

目的

本文旨在使无人机在全球定位系统信号不可靠的情况下，能够近距离检测风力发电机组的表面状况，进一步提高其智能化水平。因此开发了具有点和线特征的视觉惯性里程计。

设计/方法/方法

视觉前端结合点线特征及其净化策略，首次提出以提高低纹理场景中特征跟踪的鲁棒性和分段检测器的快速性。此外，惯性测量集成在关键帧之间作为约束，以减少仅视觉系统中存在的跟踪误差。其次，构建了基于图的视觉惯性后端。为了有效地参数化线特征，采用对室外光不敏感的无限线表示，其中选择 Plücker 和 Cayley 进行线重投影和非线性优化。此外，为了更好的准确性，分析导出了线重投影误差的雅可比行列式。

发现

在风电场的各种场景中进行实验。结果表明，在复杂的风电场环境中，具有点和线特征的紧耦合视觉惯性里程计在所有样本上比传统算法更精确。此外，构建的线特征图可用于以下自主导航的研究。

原创性/价值

所提出的视觉惯性里程计在强电磁干扰、低纹理和光照变化的风电场中表现良好。