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Desenvolvimento e teste de um protótipo móvel com sensores low cost
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Apesar de grande parte da poluição ter lugar no exterior, o ambiente interior não está incólume às movimentações de ar que a trazem para dentro dos edifícios, poluição essa nas grandes cidades com origem nos produtos da combustão ou operações industriais. Casos extremos de poluição são, por exemplo, cidades como Beijing com graves casos de smog nos últimos anos. A juntar à poluição exterior que inevitavelmente contamina os espaços interiores, temos também a própria habitação do edifício que gera a produção de CO2 por parte dos ocupantes, o que também afeta a qualidade do ar. Todos estes fatores levam a uma preocupação acrescida na compreensão e monitorização de determinados gases e os seus impactos na saúde humana. Para se poder afirmar que existem impactos e que existe presença de gases nocivos no ar ambiente, é preciso instrumentação capaz de os detetar. A ideia para esta dissertação surge no contexto da campanha Breathable Cities World Campaign, uma campanha filantrópica que visa contribuir para a melhoria da qualidade de vida do homem em completa harmonia com o ambiente. Com o intuito de quantificar os poluentes, a iniciativa Breathable Cities Campaign utilizou equipamentos extremamente dispendiosos na ordem dos milhares de euros. Esta dissertação procura obter o mesmo tipo de informação quantitativa dos gases, mas através de aparelhos low cost na ordem das dezenas de euros utilizando uma placa Arduíno que faz de interface entre uma cloud network e os sensores DHT11, MQ-131 e MG-811, servindo assim como plataforma de motivação da dissertação, sendo o principal desafio a construção e teste do protótipo. Com esta dissertação disponibilizam-se as ferramentas para qualquer académico recrear esta experiência e criar uma estação de monitorização de gases com um peso financeiro menor, o preço de todos os componentes totalizou 158.3 euros e o protótipo tem um peso de cerca de 442 gramas. O foco na instrumentação foi alvo de grande ponderação, pois é necessário estudar aprofundadamente
toda a temática dos sensores e os seus métodos de comunicação, assim como a melhor forma de proceder à construção e teste do aparelho. Para se testar o funcionamento do protótipo foi prudente considerar dois tipos de calibrações possíveis dos sensores de CO2 e O3, porém, o método dos mínimos quadrados revelou-se superior às metodologias de fábrica propostas devido à sua simplicidade. Os dados obtidos foram satisfatórios, no entanto é preciso relembrar que estamos a falar de sensores extremamente low cost e que deverão ser efetuados testes mais extensos em melhores condições de calibração. Foi possível concluir esta dissertação com um protótipo funcional capaz de fazer medições rudimentares e efetuar comunicação por cloud network. É um proof-of-concept com espaço para melhorias como a redução das dimensões e do peso investindo em circuitos integrados ou placas PCB. É possível também testar-se a utilização de sensores mais robustos que podem teoricamente proporcionar melhores resultados de calibração ao depender menos de fatores como a temperatura e a humidade, ou simplesmente assegurar melhores condições de calibração com os sensores que foram testados.
Despite a big portion of pollution being generated outdoors, indoor environment is not unaffected by air mass movements that bring that pollution inside. In big cities pollution has its origins in combustion or industrial operations and can be observed, in extreme, in cities like Beijing, with severe cases of smog in the past years. Besides outdoor pollution that inevitably contaminates indoor environments, we also have the CO2 production associated with the presence of users in indoors spaces, which by itself also affects air quality. All these factors further the necessity of monitoring and comprehending pollutants and their impacts on human health. In order to make affirmations about the impact of air pollutants and measure the presence of such pollutants in ambient air, we need instrumentation that is capable of detecting them. The idea for this dissertation comes about in the context of the Breathable Cities World Campaign, a philanthropic campaign whose objective is to promote a better quality of life for mankind and the balance between man and nature. The Breathable Cities World Campaign, with the purpose of quantifying air pollutants, used extremely expensive equipment with values in the range of thousands of euros. This dissertation procures to obtain the same type of quantifying information, but with low cost devices with a price in the dozens of euros by making use of an Arduino Board, which acts as an interface between a cloud network and a DHT11, MQ-131 and MG-811 sensors. This served as the motivational platform for this dissertation making the construction and testing of a low cost prototype the main focus. This dissertation gives the tools necessary for any academic to recreate the experience and create a cheap air quality monitoring station. The prototype which weighs about 442 grams has amounted to a total expenditure of 158.3 euros. The focus on instrumentation was target of great analysis as it’s necessary to deeply study the whole thematic of sensors and how they operate. It was also important to understand their methods of communication and how we should proceed with the construction and test of the device. A cautious approach was taken with the calibration of the CO2 and O3 sensors taking two different methods into consideration. The minimum squares method revealed itself as the superior approach when compared with factory methodologies, due to its simplicity. The data gathered from the sensors was satisfactory though it should be noted that we’re discussing extremely low cost sensors and we should be careful with taking conclusions without making more extensive tests with better calibration conditions. It was possible to conclude this dissertation with a functional prototype that was capable of making rudimentary measurements and communicate through cloud networking. It’s a proof-of-concept prototype with room for improvement, such as reducing the dimensions and weight by investing in integrated circuits or PCB boards. It’s also possible to theoretically obtain better results in calibration tests by testing more robust sensors that have less dependency of factors such as temperature and humidity, or we could use the same sensors in this dissertation but with better calibration conditions.
Despite a big portion of pollution being generated outdoors, indoor environment is not unaffected by air mass movements that bring that pollution inside. In big cities pollution has its origins in combustion or industrial operations and can be observed, in extreme, in cities like Beijing, with severe cases of smog in the past years. Besides outdoor pollution that inevitably contaminates indoor environments, we also have the CO2 production associated with the presence of users in indoors spaces, which by itself also affects air quality. All these factors further the necessity of monitoring and comprehending pollutants and their impacts on human health. In order to make affirmations about the impact of air pollutants and measure the presence of such pollutants in ambient air, we need instrumentation that is capable of detecting them. The idea for this dissertation comes about in the context of the Breathable Cities World Campaign, a philanthropic campaign whose objective is to promote a better quality of life for mankind and the balance between man and nature. The Breathable Cities World Campaign, with the purpose of quantifying air pollutants, used extremely expensive equipment with values in the range of thousands of euros. This dissertation procures to obtain the same type of quantifying information, but with low cost devices with a price in the dozens of euros by making use of an Arduino Board, which acts as an interface between a cloud network and a DHT11, MQ-131 and MG-811 sensors. This served as the motivational platform for this dissertation making the construction and testing of a low cost prototype the main focus. This dissertation gives the tools necessary for any academic to recreate the experience and create a cheap air quality monitoring station. The prototype which weighs about 442 grams has amounted to a total expenditure of 158.3 euros. The focus on instrumentation was target of great analysis as it’s necessary to deeply study the whole thematic of sensors and how they operate. It was also important to understand their methods of communication and how we should proceed with the construction and test of the device. A cautious approach was taken with the calibration of the CO2 and O3 sensors taking two different methods into consideration. The minimum squares method revealed itself as the superior approach when compared with factory methodologies, due to its simplicity. The data gathered from the sensors was satisfactory though it should be noted that we’re discussing extremely low cost sensors and we should be careful with taking conclusions without making more extensive tests with better calibration conditions. It was possible to conclude this dissertation with a functional prototype that was capable of making rudimentary measurements and communicate through cloud networking. It’s a proof-of-concept prototype with room for improvement, such as reducing the dimensions and weight by investing in integrated circuits or PCB boards. It’s also possible to theoretically obtain better results in calibration tests by testing more robust sensors that have less dependency of factors such as temperature and humidity, or we could use the same sensors in this dissertation but with better calibration conditions.
Descrição
Tese de mestrado integrado em Engenharia da Energia e do Ambiente, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, em 2018
Palavras-chave
Engenharia da Energia e do Ambiente Teses de mestrado - 2018