Resultados da pesquisa - "Afonso, José A."

Catálogo de Publicações - "Afonso, José A."

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  1. 1

    A fly-by-wireless UAV platform based on a flexible and distributed system architecture

    Publicação
    por Afonso, José A.
    Outros Autores: Coelho, Ezequiel T.; Macedo, Ricardo; Carvalhal, Paulo; Silva, Luís F.; Almeida, Heitor Manuel Santos et al.
    This paper reports and describes the diverse stages concerning the development of an unmanned aerial vehicle (UAV) named “Aeronave Inteligente com Visão Artificial”, better known by its acronym as AIVA. The design and development of the first aerial platform, the onboard ommunications, the instrumentation system, the bidirectional communications platform to/from ground station, the flight control system, the navigation strategies, as well as the vision systems to help navigation and to carry out the planned surveillance missions, are addressed in this paper. One of the main innovative issues of this platform is the distributed onboard wireless network, based on Bluetooth technology and on a multiprocessor architecture system. These features increase the platform flexibility. The goals already accomplished so far reveal interesting developments to be used successfully in commercial UAV platforms.
    2006 comunicação em conferência Portugal acesso aberto
  2. 2

    IoT system for anytime/anywhere monitoring and control of vehicles’ parameters

    Publicação
    por Afonso, José A.
    Outros Autores: Sousa, Rúben A.; Ferreira, João C.; Monteiro, Vítor Duarte Fernandes; Pedrosa, Delfim Duarte Rolo; Afonso, João L.
    This paper presents an IoT (Internet of Things) system designed to allow the monitoring and control of parameters of the users’ vehicles, anytime and anywhere in the world, through the Internet. The system prototype was developed and tested using an electric vehicle (EV) and the respective sensor systems. The main components of the proposed IoT system are: a Bluetooth Low Energy (BLE) intra-vehicular wireless sensor network (IVWSN); a mobile device that acts both as the vehicle’s gateway, connecting the IVWSN to the Internet, and as the vehicle’s human machine interface (HMI); an online server/database, based on Firebase; a client, which can be either a mobile device or a personal computer; and a residential wireless sensor network (WSN). The use of a wireless network to collect sensor data inside of the vehicle introduces some advantages when compared with conventional wired networks, whereas the inclusion of a residential WSNs in the proposed IoT architecture allows the provision of additional features, such as automatic control of the EV battery charging process. Experimental results are provided to assess the performance of the developed IVWSN and HMI.
    2017 comunicação em conferência Portugal acesso aberto
  3. 3

    Wireless monitoring and management of energy consumption and power quality events

    Publicação
    por Afonso, José A.
    Outros Autores: Rodrigues, Filipe; Pereira, Pedro; Gonçalves, Henrique; Afonso, João L.
    This paper describes the design, implementation and testing of a distributed wireless system conceived for residential consumers which allows remote monitoring of energy consumption and power quality events from multiple electrical appliances. The system can be operated by the user from a central computer, which receives the collected data from a wireless sensor network based on the IEEE 802.15.4 and ZigBee standards. The development of the system involved the design and implementation of the hardware of the wireless sensor nodes; the software embedded in the network nodes, which manages the acquisition and transmission of data from the sensor nodes to the computer; as well as the user interface software in the central computer. Performance tests show that the developed prototype is able to provide measurements with very good accuracy and precision, for both voltage and current.
    2015 comunicação em conferência Portugal acesso aberto
  4. 4
  5. 5

    Wireless communication and management system for E-Bike dynamic inductive power transfer lanes

    Publicação
    por Afonso, José A.
    Outros Autores: Duarte, Helder G.; Cardoso, Luiz Alberto Lisboa Silva; Monteiro, Vítor Duarte Fernandes; Afonso, João L.
    This paper presents the design, implementation, and testing of a wireless communication system for automatic identification of e-bikes and management of their battery charging in the context of dynamic inductive wireless power transfer (DIWPT) lanes. The proposed system checks if an e-bike, uniquely identified by its RFID tag, is authorized to receive energy from the lane coils and acts accordingly. An authentication mechanism was developed based on the use of embedded Wi-Fi boards attached to the coils and communicating with a central HTTP server with a MySQL database. The developed management system also provides other features, such as the recording of the number of lane coils used by each e-bike for billing purposes. The results from experimental tests on a laboratory prototype were used to validate the developed functionalities and assess the quality of service provided by the proposed system.
    2020 artigo Portugal acesso aberto
  6. 6

    Automatic control of cycling effort using electric bicycles and mobile devices

    Publicação
    por Afonso, José A.
    Outros Autores: Rodrigues, Filipe J.; Pedrosa, Delfim Duarte Rolo; Afonso, João L.
    This paper describes the development and evaluation of a novel effort control system for cycling, which contributes to promote the users’ mobility and physical health. This system provides automatic control of the motor assistance level of an electric bicycle in order to ensure that the cyclist’s effort remains inside the desired target zone, regardless of changes in other variables which normally affect the effort, such as the slope of the road. The system presented in this paper controls the pedaling resistance perceived by the cyclist through the use of a sensor device placed inside of the bicycle crankset, which provides the required torque signal. The data processing, effort control algorithm and user interface are implemented in a smartphone application, whereas a microcontroller on the bicycle is responsible for the data acquisition, wireless data exchange with the smartphone, and real-time control of the motor assistance level. Experimental results validate the effectiveness of the implemented effort control system.
    2015 comunicação em conferência Portugal acesso aberto
  7. 7

    Design and implementation of a wireless sensor network applied to motion capture

    Publicação
    por Afonso, José A.
    Outros Autores: Silva, Hélder D.; Macedo, Pedro; Rocha, Luís A.
    This paper describes the development of a wireless sensor network prototype and its application in a motion capture system based on inertial and magnetic sensors. The system presents a portable and modular architecture and allows the monitoring of several users at the same time using a single wireless network. The target application requires the wireless sensor network to operate efficiently under high loads, since it generates data intensive traffic and needs to support a high number of sensor modules. Other requirements imposed by the application are real-time operation and reliable data delivery. In order to provide the quality of service required by the application, an enhanced version of the LPRT medium access control protocol was developed and implemented in devices compliant with the IEEE 802.15.4 standard at the physical layer. Simulation results show that the proposed modifications improve the performance of the protocol. The implementation of the protocol is validated through the experimental results presented.
    2011 comunicação em conferência Portugal acesso aberto
  8. 8

    Acesso local sem fios em redes de comunicação: escalonamento de tráfego de tempo real em sistemas de aquisição de dados e controlo

    Publicação
    por Afonso, José A.
    Este trabalho propõe soluções destinadas a optimizar o transporte do tráfego de sistemas de aquisição de dados e controlo, utilizando redes de comunicação sem fios para a interligação de unidades remotas a uma unidade central. O tráfego gerado por estes sistemas normalmente possui requisitos de tempo real, pelo que a rede sem fios utilizada deve ser capaz de suportar os requisitos de qualidade de serviço (QoS) das aplicações. No entanto, apesar de dar prioridade ao transporte de tráfego com requisitos de tempo real (isócrono), o sistema proposto admite também a transmissão, em simultâneo, de tráfego assíncrono, de forma a permitir a integração de serviços de natureza diferente sobre a mesma plataforma de comunicação. A largura de banda disponível para operação das redes sem fios é escassa, e tem que ser partilhada por todas as unidades. Além disso, a taxa de erros no canal costuma ser bem mais elevada e variável do que nas redes cabladas. Devido a esses problemas, os mecanismos de controlo de acesso ao meio, controlo de erros e escalonamento de tráfego implementados pela rede sem fios utilizada no sistema devem ser optimizados para garantir a qualidade de serviço das aplicações. Efectuado um estudo preliminar das tecnologias de redes sem fios disponíveis, de forma a seleccionar aquelas que apresentam as características mais adequadas para servir de base ao sistema proposto, a escolha recaiu sobre as redes HIPERLAN/2 e IEEE 802.11. Não sendo viável o recurso à utilização de sistemas reais, foi desenvolvido e implementado um modelo de simulação detalhado para cada uma destas redes de acordo com as respectivas normas. Com base nestes modelos, propõem-se algoritmosde escalonamento do tráfego de dados e controlo que fornecem garantias de qualidade de serviço ao tráfego isócrono, ao mesmo tempo que permitem o transporte de tráfego assíncrono no sistema. Os resultados obtidos nas simulações permitem avaliar o desempenho do sistema, mesmo quando este é sujeito a erros no canal, e comparar a qualidade de serviço da rede HIPERLAN/2 com a da rede IEEE 802.11. A tese inicia-se com a introdução dos conceitos fundamentais à compreensão do trabalho apresentado, à qual se segue a descrição das diversas tecnologias de redes sem fios existentes, realçando as normas HIPERLAN/2 e IEEE 802.11. Após a descrição dos modelos de simulação e algoritmos desenvolvidos, apresentam-se os resultados obtidos com os dois sistemas propostos
    2004 tese de doutoramento Portugal acesso aberto
  9. 9

    Performance evaluation of bluetooth low energy for high data rate body area networks

    Publicação
    por Afonso, José A.
    Outros Autores: Maio, António F.; Simões, Ricardo João Ferreira
    Bluetooth Low Energy (BLE) is a promising wireless network technology, in the context of body area network (BAN) applications, to provide the required quality of service (QoS) support concerning the communication between sensor nodes placed on a user’s body and a personal device, such as a smartphone. Most previous BLE performance studies in the literature have focused primarily in networks with a single slave (point-to-point link) or traffic scenarios with relatively low data rate. However, many BAN sensors generate high data rate traffic, and several sensor nodes (slaves) may be actively sending data in the same BAN. Therefore, this work focuses on the evaluation of the suitability of BLE mainly under these conditions. Results show that, for the same traffic, the BLE protocol presents lower energy consumption and supports more sensor nodes than an alternative IEEE 802.15.4-based protocol. This study also identifies and characterizes some implementation constraints on the tested platforms that impose limits on the achievable performance.
    2016 artigo Portugal acesso aberto
  10. 10

    An intra-vehicular wireless sensor network based on Android mobile devices and bluetooth low energy

    Publicação
    por Afonso, José A.
    Outros Autores: da Costa e Silva, Rita Baldaia; Afonso, João L.
    This chapter presents the development and test of an intra-vehicular wireless sensor network (IVWSN), based on Bluetooth Low Energy (BLE), designed to present to the driver, in real-time, information collected from multiple sensors distributed inside of the car, using a human-machine interface (HMI) implemented on an Android smartphone. The architecture of the implemented BLE network is composed by the smartphone, which has the role of central station, and two BLE modules (peripheral stations) based on the CC2540 system-on-chip (SoC), which collect relevant sensor information from the battery system and the traction system of a plug-in electric car. Results based on an experimental performance evaluation of the wireless network show that the network is able to satisfy the application requirements, as long as the network parameters are properly configured taking into account the peculiarities of the BLE data transfer modes and the observed limitations of the BLE platform used in the implementation of the IVWSN.
    2018 comunicação em conferência Portugal acesso aberto