RA-LIO: Active Three-Stage Robust Frontend With Dual-Check Adaptive Mapping and Multilevel Vertical Constraints

Tightly coupled LiDAR-inertial odometer (LIO) often encounters robustness bottlenecks during violent motion due to two core issues: first, passive keyframe acceptance strategies fail to filter low-quality measurements introduced by abnormal motion; second, the absence of effective constraints leads to cumulative vertical drift on rough terrain. To address these challenges, this article introduces robustness-aware LIO (RA-LIO), a novel framework powered by an active three stage robust frontend wi