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- Indoor wayfinding using visible light communicationPublication . Vieira, Manuela; Vieira, Manuel Augusto; Louro, Paula; Fantoni, Alessandro; Vieira, PedroOptical wireless communication has been widely studied during the last years in short-range applications. This paper investigates the applicability of an intuitive wayfinding system in complex buildings using Visible Light Communication (VLC). Typical scenarios include finding places, like a particular shop or office, guiding users across different floors, through elevators and stairs. Data from the sender is encoded, modulated and converted into light signals emitted by the transmitters. Tetra-chromatic white sources are used providing a different data channel for each chip. At the receiver side, the modulated light signal, containing the ID and the 3D geographical position of the transmitter and wayfinding information, is received by SiC photodetector with light filtering and demultiplexing properties. Since lighting and wireless data communication is combined, each luminaire for downlink transmission become a single cell, in which the optical access point (AP) is located in the ceiling and the mobile users are scattered within the overlap discs of each cells underneath. The light signals emitted by the LEDs are interpreted directly by the receivers of the users positioned underneath. The effect of the location of the Aps is evaluated and a model for the different cellular networks is analyzed. Orthogonal topologies are tested, and a 3D localization design, demonstrated by a prototype implementation, is presented. Uplink transmission is implemented and the 3D best route to navigate through venue calculated. Buddy wayfinding services are also implemented. The results showed that the system make possible to determine the position of a mobile target inside the network, to infer the travel direction along the time and to interact with information received and to optimize the route towards a static or dynamic destination.
- VLC-based geo-localization for automated logistics control using AVGsPublication . Louro, Paula; Rodrigues, João; Vieira, Manuela; Vieira, Manuel Augusto; Vieira, PedroIncreasing interest in indoor navigation has recently been generated by devices with wireless communication capabilities that enabled a wide range of applications and services. The rise of the Internet of Things (IoT) and the inherent end-to end connectivity of billions of devices is very attractive for indoor localization and proximity detection. Other fields, such as, marketing and customer assistance, health services, asset management and tracking, can also benefit from indoor localization. Different techniques and wireless technologies have been proposed for indoor location, as the traditional Global Positioning System (GPS) has a very poor, unreliable performance in a closed space. The work presented in this research proposes the use of an indoor localization system based on Visible Light Communication (VLC) to support the navigation and operational tasks of Autonomous Guided Vehicles (AVG) in an automated warehouse. The research is mainly focused on the development of the navigation VLC system, transmission of control data information and decoding techniques. As part of the communication system, trichromatic white LEDs are used as emitters and a-SiC:H/a-Si:H based photodiodes with selective spectral sensitivity, are used as receivers. Through the modulation of the RGB LEDs, the downlink channel establishes an infrastructure-to-vehicle link (I2V) and provides position information to the vehicle. The decoding strategy is based on accurate calibration of the output signal. Characterization of the transmitters and receivers, description of the coding schemes and decoding algorithms will be the focus of discussion in this paper.
- Dynamic VLC navigation system in crowded buildingsPublication . Vieira, Manuela; Vieira, Manuel Augusto; Louro, Paula; Fantoni, Alessandro; Vieira, PedroThis paper investigates the applicability of an intuitive risk of transmission wayfinding system in public spaces, virtual races, indoor large environments and complex buildings using Visible Light Communication (VLC). Typical scenarios include: finding places, like a particular shop or office, guiding users across different floors, and through elevators and stairs. The system is able to inform the users, in real time, not only of the best route to the desired destination, through a route without clusters of users, but also of crowded places. Data from the sender is encoded, modulated and converted into light signals emitted by the transmitters. Tetra chromatic white sources are used providing a different data channel for each chip. At the receiver side, the modulated light signal, containing the ID and the 3D geographical position of the transmitter and wayfinding information, is received by a SiC optical sensor with light filtering and demultiplexing properties. Since lighting and wireless data communication is combined, each luminaire for downlink transmission becomes a single cell, in which the optical Access Point (AP) is located in the ceiling and the mobile users are scattered across the overlap discs of each cell, underneath. The light signals emitted by the LEDs are interpreted directly by the receivers of the positioned users. Bidirectional communication is tested. The effect of the location of the Aps is evaluated and a 3D model for the cellular network is analyzed. In order to convert the floorplan to a 3D geometry, a tandem of layers in a orthogonal topology is used, and a 3D localization design, demonstrated by a prototype implementation, is presented. Uplink transmission is implemented, and the 3D best route to navigate through venue is calculated. Buddy wayfinding services are also considered. The results showed that the dynamic VLC navigation system enables to determine the position of a mobile target inside the network, to infer the travel direction along the time, to interact with received information and to optimize the route towards a static or dynamic destination.
- Indoors geolocation based on visible light communicationPublication . Louro, Paula; Vieira, Manuela; Vieira, Manuel AugustoThis paper presents the use of a selective device based on a-SiC:H/a-Si:H for the photodetection of visible signals emitted by red, green and blue emitters in a Visible Light Communication (VLC) system. The VLC system employs RGB white LEDs to provide both illumination and information transmission. The acquisition and processing of the measured photocurrent allows the identification of the induced optical excitation, which encodes the spatial position. The system is designed so that the detector’s s spatial location can be obtained based on the identification of the received optical signals. The methodology used for the photocurrent signal processing involves Fourier transform analysis for frequency identification and the use of a photodetector with spectral selective properties of wavelength identification. A full characterization of the photodetector is presented together with the physical operation that plays the key role in the detection of the output photocurrent.
- Cooperative self-localization and wayfinding services through visible light communicationPublication . Vieira, Manuela; Vieira, Manuel Augusto; Louro, Paula; Fantoni, Alessandro; Vieira, PedroA Visible Light Communication (VLC) cooperative system that supports guidance services and uses an edge/fog based architecture for wayfinding services is presented. The integrated dynamic navigation system consists of multiple transmitters (luminaries) which transmit the map information and path messages necessary for wayfinding. The luminaires used for downlink transmission are equipped with one of two types of controllers: mesh controllers or cellular controllers, which, respectively, forward messages to other devices in the vicinity or to the central manager. Mobile optical receivers, collect the data, extracts theirs location to perform positioning and, concomitantly, the transmitted data from each transmitter. Uplink transmission is implemented and the best route to navigate through venue calculated. Each luminaire, through VLC, reports its geographic position and specific information to the users, making it available for use. Bidirectional communication is implemented and the best route to navigate through venue calculated. Buddy wayfinding services are also considered. Results indicate that the system is able to perform not just the self-localization, but also infer the travel direction and interact with it, optimizing the route to a static or dynamic destination.
- Geolocation and wayfinding services using visible light communicationPublication . Vieira, Manuela; Vieira, Manuel Augusto; Louro, Paula; Vieira, PedroThis paper investigates the applicability of an intuitive wayfinding system in complex buildings using Visible Light Communication (VLC). Typical scenarios include finding places. Data from the sender is encoded, modulated and converted into light signals emitted by the transmitters. Tetra-chromatic white sources are used providing a different data channel for each chip. At the receiver, the modulated light signal, containing the ID and the 3D geographical position of the transmitter and wayfinding information, is received by SiC photodetector with light filtering and demultiplexing properties. Each luminaire for downlink transmission become a single cell, in which the optical access point (AP) is located in the ceiling and the mobile users are scattered within the overlap discs of each cells underneath. The light signals emitted by the LEDs are interpreted directly by the receivers of the users underneath. The effect of the location of the APs is evaluated and a model for the cellular networks is analyzed using orthogonal topologies. A 3D localization design, demonstrated by a prototype implementation, is presented. Uplink transmission is also implemented and the 3D best route to navigate calculated. The results showed that the system allows to determine the position of a mobile target inside the network, to infer the travel direction along the time and to interact with information received optimizing the route towards the destination.
- Visible light communication cooperative system to support indoor guidance servicesPublication . Vieira, Manuela; Vieira, Manuel Augusto; Louro, Paula; Rodrigues, João; Vieira, PedroTo support people’s wayfinding activities we propose a Visible Light Communication (VLC) cooperative system that supports guidance services and uses an edge/fog based architecture for wayfinding services. A mesh cellular hybrid structure is proposed. The dynamic navigation system is composed of several transmitters (ceiling luminaries) which send the map information and path messages required to wayfinding. The luminaires are equipped with one of two types of nodes: a “mesh” controller that connects with other nodes in its vicinity and can forward messages to other devices in the mesh, effectively acting like routers nodes in the network and a “mesh/cellular” hybrid controller, that is also equipped with a modem providing IP base connectivity to the central manager services. These nodes acts as border router and can be used for edge computing. Mobile optical receivers, using joint transmission, collect the data at high frame rates, extracts theirs location to perform positioning and, concomitantly, the transmitted data from each transmitter. Each luminaire, through VLC, reports its geographic position and specific information to the users, making it available for whatever use. Bidirectional communication is implemented and the best route to navigate through venue calculated. The results show that the system makes possible not only the self-localization, but also to infer the travel direction and to interact with information received optimizing the route towards a static or dynamic destination.
- Geolocalization and navigation by visible light communication to address automated logistics controlPublication . Louro, Paula; Vieira, Manuela; Vieira, Manuel AugustoGlobal 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.
- Navigation, routing and geolocation through visible light communicationPublication . Vieira, Manuela; Vieira, Manuel Augusto; Louro, Paula; Fantoni, Alessandro; Vieira, PedroTo support people’s wayfinding activities in crowded buildings this paper proposes a method able to generate landmark route and alert instructions using Visible Light Communication .The system is composed of several ceiling luminaries transmitters which send the map information, alerts and the path messages required to wayfinding. The system informs the users, in real time, not only of the best route to the desired destination, through a route without clusters of users, but also of crowded places. Data is encoded, modulated and converted into light signals. An architecture based on a mesh cellular hybrid structure was used. The luminaires are equipped with one of two types of nodes: a “mesh” controller that connects with other nodes in its vicinity and can forward messages to other devices in the mesh, acting like routers nodes in the network and a “mesh/cellular” hybrid controller, that is also equipped with a modem providing IP base connectivity to the central manager services. Each luminaire for downlink can forward messages to other devices or to the central manager services. Mobile optical receivers, collect the data, extracts theirs location to perform positioning and, concomitantly, the transmitted data from each transmitter. Uplink transmission is implemented and the best route to navigate through venue calculated. Buddy wayfinding services are also considered. The results show that the system makes possible not only the self-localization, but also to infer the travel direction and to interact with information received optimizing the route towards a static or dynamic destination.