4.6. Think first

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Del curso dictado por Moscow Institute of Physics and Technology

Building Arduino robots and devices

215 calificaciones

Moscow Institute of Physics and Technology

Building Arduino robots and devices

215 calificaciones

For many years now, people have been improving their tools, studying the forces of nature and bringing them under control, using the energy of the nature to operate their machines. Last century is noted for the creation of machines which can operate other machines. Nowadays the creation of devices that interact with the physical world is available to anyone. Our course consists of a series of practical problems on making things that work independently: they make their own decisions, act, move, communicate with each other and people around, and control other devices. We will demonstrate how to assemble such devices and programme them using the Arduino platform as a basis. After this course, you will be able to create devices that read the data about the external world with a variety of sensors, receive and forward this data to a PC, the Internet and mobile devices, and control indexing and the movement. The creation of such devices will involve design, the study of their components, the assemblage of circuit boards, coding and diagnostics. Along with the creation of the devices themselves, you will perform visualization on a PC, create a web page that will demonstrate one of your devices, and figure out how an FDM 3D-printer is configured and how it functions. Besides those keen on robotics or looking to broaden their horizons and develop their skills, the course will also be useful to anyone facing the task of home and industrial automation, as well as to anyone engaged in industrial design, advertising and art. The course does not require any special knowledge from the participants and is open even to students of upper secondary school. Programming skills and the level of English allowing to read technical documentation would be an advantage, but this is not obligatory. The entire course is dedicated to practice, so the best way for you would be to get hold of some electronics, follow the illustrated examples and experiment on your own. The kits can be purchased here: kits.cyberphysica.ru. Taught by: Alexey Perepelkin, head of Robotics department in the Laboratory of innovative educational technologies at MIPT Taught by: Dmitry Savitsky, researcher in the Laboratory of innovative educational technologies at MIPT

De la lección

Week 4

After going through Week 4, you will be able to connect your device to a network, plan its creation beforehand , control heavy loads, and power your device correctly.

4.1. Week overview0:50

4.2. Submersible pump2:02

4.3. Field transistor and relay6:40

4.4. Power supply6:47

4.5. Planning6:07

4.6. Think first7:46

4.7. Soil humidity sensor2:16

4.8. Where do web pages come from4:10

4.9. How to transmit data to a network11:35

4.10. How to receive a command from a network8:14

4.11. Finite-state automaton5:13

4.12. WaterMe program basics and switch7:18

4.13. Errors that we often encounter7:03

4.14. The longest sketch so far12:31

4.15. How WaterMe works5:20

Conoce a los instructores

Алексей Перепелкин
Руководитель направления развития цифрового творчества
Центр инновационных образовательных технологий МФТИ
Дмитрий Савицкий
Научный сотрудник
Лаборатория инновационных образовательных технологий МФТИ

Okay, so we are building an automatic watering system,

which will be activated in certain

weather conditions.

Besides, we will be able to check the weather conditions on the

web page after we’ve connected to a network.

We will also be able to activate the automatic watering system from that same web page.

Let’s start by saying that this is a watering system,

so we will definitely have a pump.

Like I said, the system is

dependent on weather conditions.

What weather conditions?

We will be considering soil humidity, atmospheric temperature

and lightness.

You might already know that various plants prefer different treatment.

So, in fact, we can consider some other parameters too, like

soil acidity, watering schedule,

aka the exact time when the plants will be watered, atmospheric pressure or air humidity.

However, the first three parameters will suffice to act as a basis.

For instance, we can write out that the plant needs not to be watered

in darkness or when the temperature is lower than “x” and so on.

Thus, with the help of these three sensors we will know

when the plant needs to be watered.

We then need to communicate our data from the sensors

to the web page, if we want it to be displayed there.

Now this is something new.

For this purpose, we are going to use a new expansion card called the Ethernet shield,

which will allow us to connect Arduino to the local network

and then to the Internet.

This means that the web page output will be realized with the help of the Ethernet shield.

Consequently, the command to water

the flowers will also be realized accordingly.

Everything seems fine for now, but when we start putting the system

to practice, we might notice that the pumped water comes to an end.

As we know, the pump doesn’t like pumping pure air.

That’s why we will need to determine

the moment when there is no more water in the container.

As a result, a new function appears

which was not mentioned in the

description of the device.

We will need to find a way to

determine whether or not there is water in the container.

I can suggest three options off the top of my head: use an ultrasonic

distance meter, point it to the container with water and

measure the water level.

Thus, when the water level is too low,

i.e. when the distance to the water is too high, it’ll mean that there is no more water.

This method has another advantage: we can measure out water more accurately.

If we know the water surface area and the distance to it,

we will be able to figure out the volume of the pumped water.

This is our first option.

Another option is: we can place some float in the container with

a magnet on it,

and install a Hall sensor on the body of our device (aka magnetic Field sensor). Thus, we will be

able to monitor when the magnet passes by the sensor.

Otherwise we can draw some colored marking on the float,

and determine with the help of a grey color sensor

if the marking has passed by the sensor.

For now, I’m suggesting the simplest option which we shall name

“wires in water”.

What we need to do, is simply place 2 wires on the bottom of the container and transmit a signal onto one of them,

and use the second one to read off the signal.

Since our water is not distilled,

it contains some matter, which makes it a conductor.

If both ends are in the water, we will be receiving

a simple digital signal at the input, which will resemble a button being pushed.

By the way, when we were preparing to shoot this video, my colleague suggested

another clever option: we can direct a laser ray in the container,

which will refract differently when

it passes through water or an empty container.

By the refraction of the ray we can determine whether or not there is water in the container.

But we will go with the simple option dubbed “wires in water”.

What will we do when we find out that there is no more water left?

Connecting to a water pipe line to refill the container would be

a bit too much.

That’s why all we can do is inform the

user of this emergency and cease the watering process in order not to agonize the pump.

To inform the user, we can try an audio alarm

if the user is nearby.

Another useful thing would be to display the information on the web page, because

if you are on vacation, for instance, and you are closely monitoring your plants back home,

when you find out that

there is no more water in the container, you won’t be able to automatically water it, so you’ll have to

take measures and maybe even return home

to refill the container.

By and large, we have a basic device with a pump, an Ethernet shield and sensors,

to which we have added two wires: a water level sensor and

a piezo buzzer which indicates when there is no more water left.

What about the transmission of the signal?

We already know how to connect the temperature and the light sensors.

The connection of the soil humidity sensor is still Greek to us.

We will have to work on that.

We also know how to connect the pump

by using an agent, which is a transistor in the “Power key” module.

We connect the Ethernet shield

as an expansion card. But what do we do with the code and with

all this web page stuff?

We still don’t know, that’s why we have another blank space here.

We can receive and record simple digital signals,

as well as work with a piezo buzzer.

Thus, we have two blank spaces in our diagram

which we need to figure out.

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