College of Automation, Harbin Engineering University, Harbin 150001, China.
Sensors (Basel). 2019 Dec 31;20(1):237. doi: 10.3390/s20010237.
Localization and mapping are key requirements for autonomous mobile systems to perform navigation and interaction tasks. Iterative Closest Point (ICP) is widely applied for LiDAR scan-matching in the robotic community. In addition, the standard ICP algorithm only considers geometric information when iteratively searching for the nearest point. However, ICP individually cannot achieve accurate point-cloud registration performance in challenging environments such as dynamic environments and highways. Moreover, the computation of searching for the closest points is an expensive step in the ICP algorithm, which is limited to meet real-time requirements, especially when dealing with large-scale point-cloud data. In this paper, we propose a segment-based scan-matching framework for six degree-of-freedom pose estimation and mapping. The LiDAR generates a large number of ground points when scanning, but many of these points are useless and increase the burden of subsequent processing. To address this problem, we first apply an image-based ground-point extraction method to filter out noise and ground points. The point cloud after removing the ground points is then segmented into disjoint sets. After this step, a standard point-to-point ICP is applied into to calculate the six degree-of-freedom transformation between consecutive scans. Furthermore, once closed loops are detected in the environment, a 6D graph-optimization algorithm for global relaxation (6D simultaneous localization and mapping (SLAM)) is employed. Experiments based on publicly available KITTI datasets show that our method requires less runtime while at the same time achieves higher pose estimation accuracy compared with the standard ICP method and its variants.
定位和建图是自主移动系统执行导航和交互任务的关键要求。迭代最近点(ICP)算法广泛应用于机器人领域的 LiDAR 扫描匹配。此外,标准 ICP 算法在迭代搜索最近点时仅考虑几何信息。然而,在动态环境和高速公路等具有挑战性的环境中,ICP 算法单独无法实现精确的点云配准性能。此外,在 ICP 算法中搜索最近点的计算是一个昂贵的步骤,这限制了它满足实时要求的能力,尤其是在处理大规模点云数据时。在本文中,我们提出了一种基于分段的扫描匹配框架,用于六自由度位姿估计和建图。LiDAR 在扫描时会生成大量的地面点,但其中许多点是无用的,增加了后续处理的负担。为了解决这个问题,我们首先应用基于图像的地面点提取方法来过滤噪声和地面点。去除地面点后的点云然后被分割成不相交的集合。在这一步之后,应用标准的点到点 ICP 来计算连续扫描之间的六自由度变换。此外,一旦在环境中检测到闭环,就会采用 6D 图优化算法进行全局松弛(6D 同时定位和建图(SLAM))。基于公开的 KITTI 数据集的实验表明,与标准 ICP 方法及其变体相比,我们的方法需要更少的运行时间,同时实现了更高的位姿估计精度。