Observability analysis of INS and lever-arm error states with CDGPS - Camera aiding

Lane level guidance is required for several Intelligent Transportation Systems (ITS) applications. To perform lane level guidance, vehicle localization accuracies on the decimeter level are required. Carrier phase Differential GPS integrated Inertial Navigation System (CDGPS - INS) is able to achieve such accuracies given a clear view of the sky and differential correction availability; however, when using an inexpensive Inertial Measurement Unit (IMU), the performance deteriorates beyond the meter level in tens of seconds in GPS denied areas. Another popular method of navigation in the literature is INS with feature-based aiding. One of the fundamental difficulties in integrating any feature-based sensor with INS is the necessity to calibrate, with commensurate accuracy, the lever arm vector and rotation matrix, i.e. extrinsic parameters, referred here as frame transformation parameters, from the INS to the feature sensor frame. This calibration can occur during the system's operation when the corresponding error state is observable. The primary objective of this paper is to analyze observability of INS error states in an integrated CDGPS - vision - INS approach and compare it with observability in CDGPS - INS and a vision - INS approaches.