Tightly Coupled Integration of GNSS/UWB/VIO for Reliable and Seamless Positioning

The technology of autonomous vehicle (AV) is critical in nowadays Intelligent Transportation Systems. To achieve the fully automated operation for AVs, one important prerequisite is the accurate and reliable seamless localization covering complex outdoor-indoor scenarios. Although many solutions have been proposed to support AV localization, it is still challenging in achieving reliable drift-free positioning in seamless urban environments. With the current on-board sensors such as GNSS, IMU, LiDAR and cameras, it is difficult to achieve accurate drift-free indoor positioning due to the lack of GNSS indoors. Meanwhile, challenges remain in reliable navigation under obscured conditions. In this paper, we propose a tightly coupled integration algorithm of GNSS RTK, Ultra-Wide Band (UWB) and Visual Inertial Odometry (VIO) to enhance the accuracy and reliability for AVs seamless localization in challenging environments. The UWB technique is innovatively incorporated into the AVs navigation system to extend absolute positioning indoors. The stereo cameras are utilized to improve positioning continuity and enhance GNSS/UWB usability in outdoor-indoor obscured environments. The proposed algorithm is evaluated over real-world datasets in complex seamless environments. The results show that the proposed algorithm achieves 0.411m and 0.077m horizontal positioning accuracy in obscured outdoor and indoor environments, yielding 71.2% and 18.1% improvements compared with the traditional LC integration schemes, respectively.