Bengala de apoio a cegos

The biggest struggle that visually impaired and blind people face on their daily basis is the ability to navigate outdoors independently and safely. In order to make the necessary deviations while maintaining the desired course, it is necessary that visually impaired travellers are capable of correctly detect possible hazards or obstacles. Even though the traditional mobility aids such as the guide dog and the white cane have proven to be valuable and effective tools in many mobility tasks, there are still situations where these means are not effective. Therefore, in the last decades, there has been a great investment in the research and development of electronic travel aids. At the University of Aveiro in the years of 2008 and 2009, were also developed two electronic canes which used ultrasounds to detect holes, drop-offs, and steps. However, in both prototypes, it was detected the presence of acoustic coupling of the signal between the emitter and receiver transducers which reduced drastically the efficiency of both devices. Thus, in this master thesis, it is proposed a solution to this issue using 3D printing also known as additive manufacturing. This technology has been growing exponentially in the last years and gaining prominence in several sectors such as industry, engineering, and medicine. In this specific case, it will be utilized to produced several prototypes of supports for the ultrasonic transducers in order to minimize the acoustic coupling.A maior dificuldade que as pessoas cegas e com deficiência visual enfrentam no seu dia-a-dia é serem capazes de se movimentarem de forma independente e segura no exterior. Por forma a serem efetuados os desvios necessários mantendo o trajecto desejado, é necessário que estas consigam detetar correctamente possíveis perigos ou obstáculos. Embora os dispositivos auxiliares de mobilidade tradicionais, como o cão guia e a bengala branca, tenham demonstrado ser ferramentas valiosas e eficazes em diversas situações, ainda existem casos em que estes meios não são eficazes. Por este motivo, durante as últimas décadas tem havido um grande investimento na pesquisa e desenvolvimento de dispositivos auxiliares de mobilidade eletrónicos. Na Universidade de Aveiro nos anos de 2008 e 2009 foram também desenvolvidas duas bengalas eletrónicas que utilizavam ultra-sons para detetar buracos, desníveis e escadas. No entanto, em ambos os protótipos foi detetada a existência de acoplamento acústico de sinal entre o transdutor emissor e o transdutor receptor, o que reduzia drasticamente a eficácia de ambos os dispositivos. Nesta dissertação propõe-se uma solução para este problema usando a impressão 3D também conhecida como manufatura aditiva. Esta tecnologia tem vindo a crescer exponencialmente nos últimos anos e ganhando maior destaque em diversos setores nomeadamente na indústria, engenharia e medicina. Neste caso em específico foi usada para produzir vários protótipos de suportes para os transdutores de ultra-sons por forma a minimizar-se ao máximo o acoplamento acústico.Mestrado em Engenharia Eletrónica e Telecomunicaçõe

Audification of Ultrasound for Human Echolocation

Individuals with functional blindness must often utilise assistive aids to enable them to complete tasks of daily living. One of these tasks, locomotion, poses considerable risk. The long white cane is often used to perform haptic exploration, but cannot detect obstacles that are not ground-based. Although devices have been developed to provide information above waist height, these do not provide auditory interfaces that are easy to learn. Development of such devices should adapt to the user, not require adaptation by the user. Can obstacle avoidance be achieved through direct perception? This research presents an auditory interface that has been designed with the user as the primary focus. An analysis of the tasks required has been taken into account resulting in an interface that audifies ultrasound. Audification provides intuitive information to the user to enable perceptive response to environmental obstacles. A device was developed that provides Doppler shift signals that are audible as a result of intentional aliasing. This system provides acoustic flow that is evident upon initiation of travel and has been shown to be effective in perceiving apertures and avoiding environmental obstacles. The orientation of receivers on this device was also examined, resulting in better distance perception and centreline accuracy when oriented outward as compared to forward. The design of this novel user interface for visually impaired individuals has also provided a tool that can be used to evaluate direct perception and acoustic flow in a manner that has never been studied before

A low-cost and low-power hole-detecting cane for the visualy impaired

Mestrado em Engenharia Electrónica e TelecomunicaçõesEste trabalho propõe uma nova bengala para cegos e amblíopes concebida com o principal objectivo de melhorar a mobilidade dos seus utilizadores através da detecção de buracos, desníveis e degraus. Uma breve pesquisa mostrou que os dispositivos “inteligentes” actualmente disponíveis apenas fornecem detecção de obstáculos à frente do utilizador. Obstáculos que podem ser facilmente detectados por contacto físico com uma vulgar bengala. Por outro lado, as associações de cegos e amblíopes deixam claro que os buracos, desníveis e degraus estão entre as suas maiores preocupações, especialmente buracos de esgoto sem tampa, mostrando que este é um campo onde a investigação e desenvolvimento tecnológicos deverão incidir. Existiu uma grande preocupação relativamente ao baixo consumo energético do dispositivo, bem como com o baixo custo global de um hipotético produto final. As técnicas desenvolvidas para a detecção de buracos baseiam-se em pulsos de ultra-sons. É utilizada energia solar para manter as pilhas carregadas de modo que o utilizador não necessite de preocupar-se frequentemente com a mudança ou carregamento das baterias. Outra característica inovadora desta bengala está relacionada com o aumento de visibilidade e segurança proporcionado ao utilizador em ambientes nocturnos ou escuros, especialmente ao atravessar ruas ou em áreas de tráfego intenso. A bengala detecta automaticamente a luz ambiente e decide ligar ou desligar uma matriz de LEDs intermitentes dispostos ao longo da bengala. Isto permite que os condutores reconheçam antecipadamente e com mais segurança o invisual e tomem as precauções necessárias. Para interacção da bengala com o utilizador são utilizados vibração e/ou sinais sonoros. Testes realizados em ambientes reais provaram a validade do conceito e dos algoritmos apresentados, permitindo detectar eficazmente buracos, desníveis e degraus, verificando-se apenas um número muito limitado de falsas detecções em superfícies muito irregulares. No entanto, todos os buracos foram detectados independentemente do tipo de superfície, mostrando que a abordagem efectuada permite melhorar a mobilidade e confiança dos cegos e amblíopes de uma forma eficaz. Este trabalho cobre todos os detalhes relativos ao desenvolvimento deste novo dispositivo, bem como os resultados obtidos. ABSTRACT: This work proposes a new cane for the visually impaired which is capable of detecting holes, drop-offs and steps, designed with the main purpose of improving the mobility of visually impaired individuals. A small research was initially conducted and showed that currently available “intelligent” canes only provide detection of obstacles ahead of the subject, obstacles which would be easily detected by physical contact with any regular cane. Furthermore, in conversations with visually impaired associations, it became clear that holes, drop-offs and steps are among their greatest concerns, especially uncovered sewer manholes, helping to realize that this was one of the fields where technological research and development should be focused. Throughout this work, there was a great concern in the low-power consumption of the device, as well as the overall low cost of a hypothetically final product. The developed techniques for hole-detection rely on pulses of ultrasounds. Solar power is used to keep the batteries charged so that the user does not need to worry about changing or charging any batteries on a regular basis. Another innovative feature of this cane is related with the increasing visibility and safety provided to the user under dark conditions, especially when crossing streets or in heavy traffic areas. The cane automatically detects the ambient light and decides to turn on or off an array of blinking LEDs along the body of the cane. This enables drivers to recognize the user earlier and better, in order to take the necessary precautions. The means of interaction between the cane and the user are vibration and/or audible signals. Field tests proved and validated the concept and algorithms presented, allowing holes, drop-offs and steps to be detected flawlessly, and with only a very limited number of false detections occurring in very irregular surfaces. Nonetheless, all the holes were detected in every kind of surface, proving this is an efficient way of bringing a clear path to the visually impaired. This work covers all the details concerning the development of this new device, as well as the results of practical field tests

Amplitude and phase sonar calibration and the use of target phase for enhanced acoustic target characterisation

This thesis investigates the incorporation of target phase into sonar signal processing, for enhanced information in the context of acoustical oceanography. A sonar system phase calibration method, which includes both the amplitude and phase response is proposed. The technique is an extension of the widespread standard-target sonar calibration method, based on the use of metallic spheres as standard targets. Frequency domain data processing is used, with target phase measured as a phase angle difference between two frequency components. This approach minimizes the impact of range uncertainties in the calibration process. Calibration accuracy is examined by comparison to theoretical full-wave modal solutions. The system complex response is obtained for an operating frequency of 50 to 150 kHz, and sources of ambiguity are examined. The calibrated broadband sonar system is then used to study the complex scattering of objects important for the modelling of marine organism echoes, such as elastic spheres, fluid-filled shells, cylinders and prolate spheroids. Underlying echo formation mechanisms and their interaction are explored. Phase-sensitive sonar systems could be important for the acquisition of increased levels of information, crucial for the development of automated species identification. Studies of sonar system phase calibration and complex scattering from fundamental shapes are necessary in order to incorporate this type of fully-coherent processing into scientific acoustic instruments

Sensors and Systems for Indoor Positioning

This reprint is a reprint of the articles that appeared in Sensors' (MDPI) Special Issue on “Sensors and Systems for Indoor Positioning". The published original contributions focused on systems and technologies to enable indoor applications

Environmental Monitoring Report January through December 2013

https://digitalcommons.memphis.edu/govpubs-tn-dept-environment-conservation-environmental-monitoring-report/1010/thumbnail.jp