PLUS-CODE+: Zero-Installment Rover Indoor Localization

PLUS-CODE+, an innovative zero-installation indoor localization system designed for autonomous robots, addressing the challenges posed by conventional indoor positioning systems (IPSs) such as extensive preinstallation and multifloor navigation difficulties. PLUS-CODE+ introduces five major innovations: 1) it eliminates the need for sensor or antenna installation, drastically simplifying deployment; 2) it utilizes optical character recognition (OCR)-based visual real-time kinematic (vRTK) to enhance global navigation satellite system (GNSS)-dead reckoning (DR) data in real time, ensuring high localization accuracy even in environments where GNSS signals are compromised; 3) it introduces a deep neural network (DNN)-based adaptive fusion model that seamlessly integrates GNSS-DR with vRTK measurements, further enhancing positioning accuracy by compensating for predictable sensor errors; 4) it incorporates a global indoor location code encoder-decoder, facilitating universal access and shareability of multifloor locations; and 5) it achieves centimeter-level accuracy in localization. Our proof-of-concept tests conducted in large multifloor environments demonstrate that PLUS-CODE+ not only meets but exceeds the precision requirements for indoor localization, attaining accuracy on par with satellite-based GNSS real-time kinematic (RTK) systems. This capability significantly enhances autonomous navigation in complex indoor settings, enabling seamless transitions between indoor and outdoor environments.