Aided Inertial Navigation with Geometric Features: Observability Analysis

In this paper, we perform observability analysis for inertial navigation systems (INS) aided by generic exteroceptive range and/or bearing sensors with different geometric features including points, lines and planes. While the observability of vision-aided INS (VINS, which uses camera as a bearing sensor) with point features has been extensively studied in the literature, we analytically show that the same observability property remains if using generic range and/or bearing measurements, and if global measurements are also available, as expected, some unobservable directions dismiss. We study in-depth the effects of four degenerate motions on the system observability. In particular, building upon the observability analysis of the aided INS with point features, we perform observability analysis for the same system but with line and plane features, respectively, and show that there exist 5 (and 6) unobservable directions for a single line (and plane) feature. Moreover, we, for the first time, analytically derive the unobservable directions for the cases of multiple lines/planes. We validate our analysis through Monte Carlo simulations.