Avaliação do uso de sinal de comunicação para o desenvolvimento de um aplicativo de localização para pessoas com deficiência visual

Abstract

The great progress in technology, specifically in smartphones, allowed a huge democratization in the access to this kind of dispositive. In conjunction to that, the competing market has made the prices to be available even for the lowest income people. As a consequence of that, the amount of Wi-Fi networks, bluetooth devices, and other types of emitted signals in establishments has greatly improved. These existing signals can be used as a localization system or the visually impaired. The GPS already does this job, but in low costs it does not provides the needed accuracy. Besides that, there are difficulties at localization tasks in indoor environments. This paper aims to take advantage of the existing information of this signals for the visually impaired to localizate themselves in indoor environments. Using trilateration algorithms and estimating the distance to these signal emitters the localization of the smartphone can be estimated. Also this paper aims to put together techniques, algorithms, metrics, and papers related to localization applied to the visually impaired. Two different applications with different purposes were developed. The first simply simulates the movement of an entity with signal sensor in a room with device emitting signals. The goal of this simulation is to understand and showcase the position guessing as the movement occurs. The second application has practical purposes and effectively obtains Wi-Fi signals of known locations and evaluates the intensity of the signal. This intensity is used to estimate the distance to the known location and infer the position of the device. The second application was tested in an environment where all the locations were already known and the error between the known location and the estimated location was measured. It was concluded that for the estimated distance between the emissor and the receiver to be properly accurate, better distance estimation techniques are needed. The intensity of the signal does not fall off in a trivial manner when the receiver is moved away from the emitter. There are other variables in the signal intensity, such as obstruction due to the presence of walls and obstacles.