Geolocalization and navigation by visible light communication to address automated logistics control

Global positioning system uses satellite signals to infer position. In buildings, however, these signals are attenuated and scattered by walls and other objects, making it impossible to measure an exact position inside them. Using the location information supplied by the lighting infrastructure, we propose an indoor navigation system based on visible light communication (VLC). The application presented relates the use of robotic solutions in a modern, efficient warehouse. As warehouses and distribution centers compete for a competitive advantage, automated guided vehicles (AGVs) are becoming increasingly popular. Our work reports a VLC-based geolocalization and navigation system to address automated logistics control. The proposed system includes VLC links and a space layout connecting RGB lamps and AGVs. The controlling flowchart, methods, and the data frame content required to support bidirectional communication between the infrastructure and AGVs are also discussed. The communication network is supported by VLC emitters using trichromatic RGB white LEDs and dedicated receivers based on a-SiC:H/a-Si:H photodiodes with selective spectral sensitivity. The downlink channel establishes the infrastructure-to-vehicle link and transmits information through the modulation of the red and blue emitters of the white RGB LEDs. The decoding strategy is based on accurate calibration of the output signal. Synchronization of the transmitted frames is used to ensure the identification of the start and end of each message. The uplink channel is used for the communication from the vehicle-to-infrastructure. This link is established using a single optical signal. The communication flowchart model was defined to establish the different communication modes and types of messages transmitted by each of the system entities. We present basic system requirements, give details on the network topology, define the communication flowchart model, and discuss the methodology used to decode the multiplexed signal transmitted by simultaneous emitters.