A Tightly Coupled VLC-Inertial Localization System by EKF

Lightweight global localization is favorable by many resource-constrained platforms working in GPS-denied indoor environments, such as service robots and mobile devices. In recent years, visible light communication (VLC) has emerged as a promising technology that can support global positioning in buildings by reusing the widespread LED luminaries as artificial visual landmarks. In this letter, we propose a novel VLC/IMU integrated system with a tightly coupled formulation by an extended-Kalman filter (EKF) for robust VLC-inertial localization. By tightly fusing the inertial measurements with the visual measurements of LED fiducials, our EKF localizer can provide lightweight real-time accurate global pose estimates, even in LED-shortage situations. We further complete it with a 2-point global pose initialization method that loosely couples the two sensor measurements. We can hence bootstrap our system with two or more LED features observed in one camera frame. The proposed system and method are verified by extensive field experiments using dozens of self-made LED prototypes.