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IMPLEMENTAÇÃO DE UM SISTEMA DE BAIXO-CUSTO PARA MEDIR IMPEDÂNCIAS MEDIÇÃO DE IMPEDÂNCIA EM LÍQUIDOS PARA EFEITOS DE DETERMINAR O SEU GRAU DE PUREZA
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| 3.77 MB | Adobe PDF |
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Resumo(s)
A água é um recurso básico de suporte de vida para qualquer ser vivo. Este projeto pro-
põe uma solução para se efetuar o controlo da qualidade das águas.
Decidiu-se criar um medidor de impedâncias de baixo custo, cuja função é gerar um
sinal, que atravesse a água várias vezes e com frequências diferentes, para posteriormente se
retirar a função transferência da mesma.
Para se obter esse resultado começou por se fazer um estudo de mecanismos e ferra-
mentas que utilizam o mesmo sistema para obter o valor da impedância, bem como qual o
microcontrolador que seria adequado para este projeto.
Após alguma deliberação pegou-se no ESP32 para testar o funcionamento dos seus con-
versores (ADC e DAC). Depois de se verificar a operabilidade destes, realizou-se o loopback
analógico e digital para analisar o aspeto do sinal, com a resolução que estes conversores
oferecem. Simultaneamente foi necessário enviar a resposta do loopback para o PC, de modo
a facilitar a análise e comparação dos sinais.
Posteriormente adicionou-se o AudioKit com conversores de resolução mais elevada e
realizou-se o mesmo loopback, de modo a comparar com os resultados obtidos apenas com
o ESP32.
Para o passo final fez-se um varrimento de frequências e com isto foi possível calcular
a função transferência e traçar o seu gráfico. Em paralelo foi desenhado um shield (circuito
impresso) para o ESP32, com as especificações do AudioKit, para atenuar o ruído e deixar o
sistema mais compacto.
Os resultados foram satisfatórios tendo em conta os contratempos, visto que conseguiu-
se medir as impedâncias de alguns circuitos de teste. Sendo este apenas um estudo preliminar
é aconselhável realizar-se um estudo mais aprofundado, com circuitos mais elaborados e ana-
lisar a relação da variação da impedância da água com a variação de minerais na mesma.
Water is a basic life support resource for any living being. This project proposes a solution for monitoring water quality. It was decided to create a low-cost impedance meter, whose function is to generate a signal that passes through the water multiple times and at different frequencies, to later extract its transfer function. To achieve this result, a study of mechanisms and tools that use the same system to obtain impedance values was conducted, as well as determining which microcontroller would be suitable for this project. After some deliberation, the ESP32 was chosen to test the function- ality of its converters (ADC and DAC). Once their operability was confirmed, an analog and digital loopback was performed to analyze the signal's appearance with the resolution these converters provide. Simultaneously, it was necessary to send the loopback response to the PC to facilitate signal analysis and comparison. Subsequently, an AudioKit with higher resolution converters was added, and the same loopback was conducted to compare the results obtained only with the ESP32. For the final step, a frequency sweep was performed, enabling the calculation of the transfer function and the plotting of its graph. In parallel, a shield (PCB) for the ESP32 was designed, following the specifications of the AudioKit, to attenuate noise and make the system more compact. The results were satisfactory considering the setbacks, as impedances of some test cir- cuits were successfully measured. Since this is only a preliminary study, it is advisable to con- duct a more in-depth investigation with more complex circuits and analyze the relationship between the variation of water impedance and the variation of the minerals in it.
Water is a basic life support resource for any living being. This project proposes a solution for monitoring water quality. It was decided to create a low-cost impedance meter, whose function is to generate a signal that passes through the water multiple times and at different frequencies, to later extract its transfer function. To achieve this result, a study of mechanisms and tools that use the same system to obtain impedance values was conducted, as well as determining which microcontroller would be suitable for this project. After some deliberation, the ESP32 was chosen to test the function- ality of its converters (ADC and DAC). Once their operability was confirmed, an analog and digital loopback was performed to analyze the signal's appearance with the resolution these converters provide. Simultaneously, it was necessary to send the loopback response to the PC to facilitate signal analysis and comparison. Subsequently, an AudioKit with higher resolution converters was added, and the same loopback was conducted to compare the results obtained only with the ESP32. For the final step, a frequency sweep was performed, enabling the calculation of the transfer function and the plotting of its graph. In parallel, a shield (PCB) for the ESP32 was designed, following the specifications of the AudioKit, to attenuate noise and make the system more compact. The results were satisfactory considering the setbacks, as impedances of some test cir- cuits were successfully measured. Since this is only a preliminary study, it is advisable to con- duct a more in-depth investigation with more complex circuits and analyze the relationship between the variation of water impedance and the variation of the minerals in it.
Descrição
Palavras-chave
ADC Circuito impresso DAC Função transferência Impedância Loopback