Contents
Motivation
Objectives
System Architecture
Motivation
Traditional agriculture is an ancient practice that man explores for self-consumption and subsistence. Until recently this practice was enough to meet human needs, but with the increase of these needs there is overexploitation of this ancestral activity.
It is estimated that by 2050 the world cereal need will be 2738 million tons, an increase of approximately 51% when compared to the data recorded in 2000 – 1818 million tonnes. This forecast indicates that there will be an increase in food demand, which occurs not because the world population is increasing, but because undernourished countries are finally gaining purchasing power and development capacity.
However, with the decrease in cultivation area due to human occupation or soil erosion, because of the use of pesticides and fertilizers by intensive agriculture, water shortage, increased demand for food and biofuel production, traditional agriculture may not be able to answer to this prediction.
This is particularly true in undernourished countries, as it is the case of the African continent countries, where, according to the FAO organization reports, soil erosion is an increasing problem.
An example of these countries is South Africa, according to the UN Environment Programme report, 90% of the country is considered arid, semi-arid or sub-humid. A country with this problem and with a forecast of population growth and rising price of cereals, can lead to a serious problem of malnutrition.
A solution being used to address these challenges and meet the future food demands is the hydroponic agriculture.
Hydroponic consists of an agriculture without soil, that is, the plants are arranged in chan-
nelized systems, whose roots are in contact with a solution containing the nutrients necessary for their growth.
When compared to traditional agriculture, hydroponic farming is a closed and precise system which allows to prevent water waste, as well as to precisely monitor and control the consumption of nutrients. Additionally, due to the precise control of all the plant environment and its food supplies, hydroponic systems allow to increase the growth rate of the plant and to cultivate it out of the planting season.
Another advantage is that, since the cultivation is done without soil, vertical plantations are possible, i.e., several layer of hydroponic systems can be stack up in the same area. This results that for the same plantation area, hydroponics can produce in larger quantities when compared to conventional farming.
With these advantages hydroponic farming is increasingly becoming a reality, which is helping not only to meet the world food demand, but also helping to solve the farming problems of many undernourished countries, as it is the case of South Africa.
Due to its precision characteristic, and in order to take the most of the hydroponic farming, hydroponic systems demand a good monitor and control system. This need arises given the vulnerability of the plants roots, because one minimal change on some of its variables, for example the pH of the water, can have to huge impact in all the hydroponic production.
There are already industrial monitor and control hydroponic systems on the market, but they are not developed having in mind undernourished countries, so their advantages are not fitted to these countries needs and are too expensive for their economic reality.
The objective of this thesis is to study the needs of South African hydroponic farm in order to carry out the survey of the requirements necessary to develop a new low-cost, easy to installation and robust hydroponic monitoring system.
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Objectives
The foundation of this thesis can be organized on its theoretical and the practical objectives.
The theoretical objectives are related with state of the art studies, namely: (1) the study of hydroponic agriculture and their monitoring systems; (2) the study of the requirements of South African hydroponic farms; (3) the study of low power wireless networks and their communication protocols, namely the Epidemic protocols.
The practical objectives are the result of the aforementioned studies, and will culminate in the development of a monitoring solution for hydroponic farms, suitable to be applied on the South African context. Such solution will be based on a low power wireless sensor network, on top of which will be running a epidemic protocol. Additionally, it would be developed a gateway to interface the hydroponic monitoring network with the outside world (the Internet).
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System Architecture
In order to address the requirements presented on objectives this thesis proposes to develop a distributed wireless communication architecture, broken down by hierarchical layers. This hierarchy is composed by three distinct layers: (1) sensing layer; (2) gathering layer; and (3) cloud layer.
The sensing layer is the lowest layer of the system, where each node periodically reads the physical quantities to monitor and sends them to the upper layer. Each node of this layer should be composed by the sensors, a battery, a microcontroller and a BLE modem .
The middle layer of the system is the Gathering layer, and each of its nodes is responsible to gather all the data sent from the lower layer, treat them and periodically send it to the Cloud layer.
The nodes of this layer should be composed by a battery, a photovoltaic panel, a BLE modem and a microcontroller.
Finally the Cloud layer, the highest layer level of the system, plays the role of gateway for the system allowing it to communicate with the outside world, i.e., the cloud layer receives the data sent from the gathering layer and sends it to a cloud service, allowing to remotely control the hydroponic farm. Each node of this system should be composed by a BLE modem to interact with the Gathering layer, and a GSM and WiFi module to communicate with the cloud service according to the communication services available at each installation. Additionally, it could be useful to add to the gathering layer a graphical interface to allow the user to use this nodes to locally consult the state of the farm.
The interaction between these three layers should be done using a communication protocol tolerant to node failure, that enables easy scalability with the least possible intervention and which is oriented to a high energy efficiency. One example of such protocol is Gossip. By using such a protocol as the bases of communication between nodes and layers, we will be able to comply with all the requirements needed for these communications.
With this approach the communication between nodes in the same layer and between nodes from different layers will be made in a epidemic form, guaranteeing robustness to node failure, easy scalability and network modification.
