Irrigation

Who are we?

We are a group of 5 Electrical Engineering students from Polytech Sorbonne Paris. This is our industrial project for our 4th year of formation.

What is this project about?

Our final product is an autonomous water pump controlling system for agricultural irrigation usage. It is meant to be used in a Burkina Fasso company that lends water pumps to agricultors, who pay for the amount of water extracted with such pumps.

How does it work?

The user sends a message contanining one or multiple "water droplet" emojis through Telegram to a bot called Dargoutech. This request is sent to the server and if the user has enough credits, a token is sent to him. He then has 24 hours to use it by going to his water pump and connecting to the local Wifi network of the Raspberry Pi:

The rollout

At the beginning of the semester, we started out with brainstorming sessions to figure out the best initial solutions to the client's needs. Once the technical solutions were identified, we tested, in groups of 2 or 3, the feasibility of such solutions. After a few tries, we refined our plan and split the team into 2 groups: software and hardware.

At the beginning of each project session, we would make a reminder of what has been done in the previous weeks, define the objectives of the session, establish the distribution of the tasks over several weeks as well as the deadlines to come.

Technical description

This project's technical implementation can be divided into 2 main parts: the hardware part the software part of our system.

Hardware

Sensors

We have programmed a set of sensors useful for monitoring pumping as well as various environmental parameters.

Thanks to the flow meter we can know the amount of water pumped per minute and then these values ​​are integrated over a given period of time to know how much water has been extracted.

Temperature and light sensors have also been configured in our system. For the luminosity, we measure the frequency of the wave perceived by the sensor and we then convert this frequency into a value in lux. The temperature is given in degrees Celsius by the sensor with the One Wire library.

Pump power supply

Our system allows to control, thanks to a simple GPIO pin of a Raspberry Pi, the the ignition and the extinction of the pump.

Controlling a pump operating with a nominal voltage of 48V and with a current of up to 17A with a Raspberry card pin, operating rather in the 5V and milliampere range, is not an easy feat. Indeed, we had to find a way to adapt these voltages and currents to each other so that they were compatible and that the board would not be damaged.

The use of an optocoupler, which makes it possible to adapt the "grounds" of the Raspberry Pi card and that of the pump to each other helped us to make this adaptation. We then used a relay that functions as a switch to send an extinction signal (a “0”) or an ignition (a “1”) to the pump.

Software

The software part can be split into 3 parts. A first backend part, the server, which allows the interaction between the user and the company. The second and most critical software part, the data exchange between the user and the system. The third part consists the pump control and water delivery algorithm.

The first part (the server) deemed less vital was started last. The interaction between the user and the server (company) is carried out through the Telegram application, widely used in Africa and which only requires a 2G network.

To initiate communication, the client sends a certain number of water drop emojis representing the number of cubic meters wished. We have chosen a pictorial representation to facilitate understanding because the potential user in small villages of countries like Burkina Fasso could be illiterate.

Once the message has been received by the server, the former examinates the quantity of water requested and whether the available credit is sufficient. If it is the case, the server encrypts the token. This token is an encrypted message containing the current date (the token is thus only available during the current day) and the number of liters. The server then sends the client this token which he can use to activate the pump.

Suggested solutions

The second part (data exchange) was done first because we considered it as the hardest to set up.

Our client initially wanted a 2G communication between the client and the electronic board. This old technology is only available with a very expensive module, which is why he proposed us a Chinese Raspberry Pi imitation board (Orange Pi) integrating the 2G module. Our team inquired about this board unknown to the general public and concluded that its use would be very difficult and would jeopardize the project. Indeed, the official documentation is non-existent, the community is small and exclusively Chinese or Russian, it is not reliable enough (many negative comments) and simply connecting the board to a monitor requires cables of non-European standards.

Final Solutions

We therefore convinced our client to opt for a Raspberry Pi solution which has the advantage of having a very large documentation and community in order to be able to meet the objectives of the project.

Added to this is the problem of cost. Indeed, the 2G module of the raspberry is worth 70€, which would have made a very substantial investment per pump considering his company will deploy many of them.

So we found a first technical communication solution: bluetooth. This is included on our board and has the advantage of being usable in all conditions, unlike the 2G module which requires an internet connection, which is very restrictive given our geographical position.

However, this solution proved to be very difficult to implement. The connection was made quickly, but the exchange of data between our Android beta application that we designed for these purposes and the board was abandoned following the advice from our supervisors to change the solution.

We therefore switched to local Wifi communication, which has many advantages. It is already present on the Raspberry Pi and we have the possibility of going downmarket because this card is available on older and therefore cheaper models. In addition, the connection is better than bluetooth and available in all conditions. Also, it allows us to offer a web page with additional and educational content, thus meeting a secondary objective of the client.

You can find a video illustrating our project in here: https://www.linkedin.com/feed/update/urn:li:activity:6937438080899403776/