Semi-Elastic LiDAR-Inertial Odometry

Existing LiDAR-inertial state estimation methods treats the state at the beginning of current sweep as equal to the state at the end of previous sweep. However, if the previous state is inaccurate, the current state cannot satisfy the constraints from LiDAR and IMU consistently, and in turn yields local inconsistency in the estimated states (e.g., zigzag trajectory or high-frequency oscillating velocity). To address this issue, this paper proposes a semi-elastic LiDAR-inertial state estimation method. Our method provides the state sufficient flexibility to be optimized to the correct value, thus preferably ensuring improved accuracy, consistency, and robustness of state estimation. We integrate the proposed method into an optimization-based LiDARinertial odometry (LIO) framework. Experimental results on four public datasets demonstrate that our method outperforms existing state-of-the-art LiDAR-inertial odometry systems in terms of accuracy. In addition, our semi-elastic LiDAR-inertial state estimation method can better enhance the accuracy, consistency, and robustness. We have released the source code of this work to contribute to advancements in LiDAR-inertial state estimation and benefit the broader research community.