3-D Collaborative Occupancy Grid-Based Inertial SLAM Based on Switching Floor Event

The miniature inertial measurement unit-based pedestrian navigation system (MIMU-PNS) has been widely discussed and researched in academia and industry, and there is a growing focus on the 3-D relative position information among multipedestrians. Nonetheless, position errors tend to accumulate over time in the MIMU-PNS, the conventional range-based collaborative navigation methods are subject to nonlinear line-of-sight (NLOS) in complex indoor environments, and depend on accurate knowledge of the pedestrian's initial relative position and heading. To address the challenges associated with 3-D position error divergence, instability of ranging information, and poor access to initial relative states in MIMU-PNS, this article proposes a 3-D collaborative occupancy grid-based inertial simultaneous localization and mapping system (3D-COGI-SLAM) based on switching floor event (SFE) matching. Our proposed system does not require ranging information and any a priori information about the building and can effectively adapt to elevator, escalator, and stair activities. The results of the three-person experiments conducted in the two building scenarios demonstrated that our system has improved performance over the conventional range-based collaborative navigation system. When the initial relative state is unknown, our system achieves similar accuracy to the known case, and the average horizontal and height positioning errors are 2.87-0.13 m, respectively.