Multi-Sensor and Analytical Constraints Tightly Augmented BDS-3 RTK for Vehicle-Borne Positioning

The third generation BeiDou Navigation Satellite System (BDS-3) can provide high-accuracy service for vehicle-borne positioning and navigation. The performance of BDS-3 in terms of accuracy, continuity, and reliability, however, are significantly degraded in environments with weak satellite observability. To improve the positioning performance of BDS-3 around the partial and complete signal-blocked areas, this paper presents a multi-sensor and analytical constraints tightly augmented BDS-3 Real-time Kinematic (RTK). The Non-holonomic Constraint (NHC), vehicle-odometer, and dual-antenna-based attitude constraints applied to restrain the drift of the position estimate from Inertial Measurement Units (IMU). Compared to previous work, it’s the first time to reveal that the Ambiguity Resolution (AR) performance of RTK can be augmented by integrating these measurements. To validate the performance of this proposed method, the drifts of position and attitude during the poor satellite observability and the impacts of those sensors and constraints on ambiguity fixing are analyzed based on an urban vehicle-borne test. The test results illustrate that the presented model brought 52.73%, 55.56%, and 49.44% positioning accuracy improvements in the north, east, and vertical components compared to the RTK mode. Meanwhile, 10.87% and 57.20% attitude accuracy enhancements in roll and heading were obtained compared to the traditional RTK/IMU tight integration mode. In addition, this presented model can retain the accuracy of position and attitude during the partial and complete satellite signal outage periods, and can also improve the ambiguity resolution performance significantly.