This work analyzes unobservable directions of Vision-aided Inertial Navigation System (VINS) and Lidar-aided Inertial Navigation System (LINS) nonlinear model. Under the assumption that there exist two features observed by the camera without occlusion, the unobservable directions of VINS are uniformly globally translation and global rotations about the gravity vector. The unobservable directions of LINS are same as VINS, while only one feature need to be observed. Also, a constraint in Observability-Constrained VINS (OC-VINS) is proved.

翻译：本文分析了视觉辅助惯性导航系统（VINS）与激光雷达辅助惯性导航系统（LINS）非线性模型的不可观测方向。在假设相机无遮挡观测到两个特征点的条件下，VINS的不可观测方向为全局均匀平移及绕重力矢量的全局旋转。LINS的不可观测方向与VINS相同，但仅需观测一个特征点。此外，本文还证明了观测约束VINS（OC-VINS）中的一项约束条件。