Caracterização de um circuito baseado em células fotovoltaicas para um sistema de posicionamento indoor

Abstract

In this work, analyses of photovoltaic (PV) cells to be used as receivers of a visible light system for indoor positioning are discussed. It is understood that photovoltaic cells retain energy from natural or artificial light and transform it into electrical energy, and can also be used as visible light receivers, in indoor environments, as it is a very accessible and wireless method. The light signal does not pass through walls, which limits the reception area. Having a good electrical model of a photovoltaic cell is crucial for creating and simulating an indoor positioning system, both in terms of DC and AC. The exact extraction of the model parameters is essential for an accurate estimate of the voltage and current generated as a function of the level of incident light. For this reason, equivalent electrical models are employed for estimation. The present work presents the technique of measuring and modelling small signal parameters based on the procedure for extracting DC parameters from a photovoltaic cell. In small signals, the regions of maximum power (MPP), open circuit (OC) and short circuit (SC) are considered. A configuration for evaluating the response of photovoltaic cells is described, and the results are subjected to an analytical parameter extraction procedure. Therefore, an approach is proposed to employ visible light in an indoor positioning system using a photovoltaic cell as a receiver. We carried out some tests to verify the transmitter data using the photovoltaic cell for characterization purposes. The project methodology uses positioning technologies such as the Received Signal Strength Indicator (RSSI) and Finger Printing/Scene Analysis. These technologies are essential for characterizing and evaluating the performance of the proposed system. The presented system provides two types of data: amplitude and frequency variations of each transmitter, in addition to the power ratio of the transmitters. From the variation in the intensity of the received signal, it is possible to determine the distance between the transmitter and the receiver. Frequency can be used to determine which transmitter is currently communicating. The results demonstrate that the proposed approach is viable and effective for indoor positioning, with potential applications in different environments. Keywords: photovoltaic cells, indoor positioning system, electrical model, parameter extraction, RSSI, digital printing, scene analysis.