A Pointcloud Registration Framework for Relocalization in Subterranean Environments

Relocalization, the process of re-establishing a robot’s position within an environment, is crucial for ensuring accurate navigation and task execution when external positioning information, such as GPS, is unavailable or has been lost. Subterranean environments present significant challenges for relocalization due to limited external positioning information, poor lighting that affects camera localization, irregular and often non-distinct surfaces, and dust, which can introduce noise and occlusion in sensor data. In this work, we propose a robust, computationally friendly framework for relocalization through point cloud registration utilizing a prior point cloud map. The framework employs Intrinsic Shape Signatures (ISS) to select feature points in both the target and prior point clouds. The Fast Point Feature Histogram (FPFH) algorithm is utilized to create descriptors for these feature points, and matching these descriptors yields correspondences between the point clouds. A 3D transformation is estimated using the matched points, which initializes a Normal Distribution Transform (NDT) registration. The transformation result from NDT is further refined using the Iterative Closest Point (ICP) registration algorithm. This framework enhances registration accuracy even in challenging conditions, such as dust interference and significant initial transformations between the target and source, making it suitable for autonomous robots operating in underground mines and tunnels. This framework was validated with experiments in simulated and real-world mine datasets, demonstrating its potential for improving relocalization. The contributions of this work are: 1) a robust framework for relocalization in challenging subterranean environments, addressing noise, occlusions, and irregular surfaces with a multi-stage registration process; 2) a computationally efficient approach, integrating ISS keypoint selection, FPFH descriptors, and NDT initialization to support real-time operations; and 3) validation of the framework on simulated and real-world mine datasets, demonstrating practical applicability for autonomous navigation in underground settings.