2. Overview
So what is this project? What does it do?
Basically this is a soil moisture monitoring
system, which detects if the moisture content
in the soil is above or below a certain
satisfactory threshold value. If it goes below
a certain critical point, it is time to water the
plant until the soil surrounding the plant is
moist enough. An arrangement of a DC motor
and a servo motor is used to control the
watering mechanism.
3. Before we start with the project itself, let’s see what led us to take up
this challenge to make this automated watering system.
In this 21st century, climate change and depletion of resources
have become a major issue to deal with. With the ever growing
population and increased demand for natural resources we
find ourselves in a middle of a crisis, a crisis which calls for
immediate action. Sustainable development must be adopted
by each one of us, both on a personal level and socio-industrial
level.
Among the teeming natural resources which make life possible
on earth, perhaps the most important is water. Water shortage
has become a crucial issue in most parts of the world. Recently,
the state of Maharashtra in India is facing a severe drought
which has already claimed many lives. Hence we see that
water conservation is of utmost importance.
4. Conventional irrigation methods use a lot of
water, and needless to say, a lot of it is
wasted on a daily basis. With the help of
advanced methods of irrigation, which
should ideally use just the correct amount of
water needed for the plants, we could save a
considerable amount of water. With the help
of soil moisture sensors, we could use just
the right amount of water needed for
irrigation – and that is the motivation of this
project.
5. Equipments used
• Arduino Uno
• Soil moisture sensor module
• Motor driver IC L293D
• Servo motor
• Pump motor
• 12V DC adapter
• Vero board
• Wires and jumper cords.
7. The main elements of the circuit
• The Arduino
• Soil Moisture Sensor
• Motor driver IC L293D
• Servo motors and DC motors
8. The Arduino
The Arduino is an open-source microcontroller based kit for
building digital devices and interactive objects that can sense and
control objects in the physical world.
The Arduino board provides sets of digital and analog I/O pins that
can be interfaced to various expansion boards ("shields") and other
circuits.
The board features RS-232 serial communication interface,
including USB on some models, for loading programs from personal
computers.
For programming the microcontrollers, the Arduino has a specific
software associated with it which provides an integrated
development environment (IDE) based on the Processing project,
which includes support for the C and C++ programming languages.
9.
10. Soil Moisture Sensor Module
Soil moisture sensors measure the volumetric water
content in soil.
Soil moisture sensors measure the volumetric water
content indirectly by using some other property of the
soil, such as electrical resistance, dielectric constant, or
interaction with neutrons, as a proxy for the moisture
content.
The Soil Moisture Sensor uses capacitance to measure
dielectric permittivity of the surrounding medium. In soil,
dielectric permittivity is a function of the water content.
The sensor creates a voltage proportional to the
dielectric permittivity, and therefore the water content of
the soil.
11. The sensor averages the water content over the
entire length of the sensor. There is a
2 cm zone of influence with respect to the flat
surface of the sensor.
12. What Does A Soil Moisture Sensor Look Like?
Here it is.
13. Motor driver IC L293D
L293D is a motor driver integrated circuit
which can control a set of two DC motors
simultaneously.
The L293D uses 5V for its own power and
external power source is needed to drive the
motors.
Motor driver is basically a current amplifier
which takes a low-current signal from the
microcontroller and gives out a proportionally
higher current signal which can control and
drive a motor.
14. The special feature of this
IC is controlling the direction
of rotation of the motor,
which is done with the help
of an H-Bridge.
The switches S1,S2,S3 and
S4 are realized by MOSFETS
and with the help of different
combinations of them
turning on or off controls the
direction of rotation of the
motor shaft.
16. Servo Motor
A servo motor is a rotary actuator that allows for precise control of
angular or linear position, velocity and acceleration.
It consists of a suitable motor coupled to a sensor for position
feedback.
The input to its control is some signal, either analogue or digital,
representing the position commanded for the output shaft.
The Arduino controls the rotation by specifying the exact angle of
rotation.
17. DC Motor
A DC motor is any of a class of electrical machines that
converts direct current electrical power into mechanical
power.
The most common types of DC motors rely on the forces
produced by magnetic fields.
A DC motor's speed can be controlled over a wide range,
using either a variable supply voltage or by changing the
strength of current in its field windings.
19. • The Soil moisture sensor continuously
monitors the volumetric moisture content in
the soil and sends that information to the
Arduino with values lying in the range 0 to
1023.
• If the soil moisture content goes below a
certain point, which is decided by the
threshold value given in the Arduino code, the
Arduino signals the servo motor and the dc
motor to start the watering mechanism.
20. • As soon as the Arduino decides that the soil
needs watering, it tells the servo motor how
much to rotate and along with it the water
holding container is tilted to let the water
flow.
• Keep in mind that all this while the pump
motor, that is, the DC Motor is running to
maintain a steady flow of water.
22. The Big Picture
• In this project, we have merely built a prototype.
But the advantages of this project are numerous.
If we can implement this technology in the real
world, a lot of water can be saved. The world
uses about 70% of freshwater for irrigation and
on the other hand irrigation multiplies yield of
most crops by almost 2 to 5 times. So irrigation
seems to be a necessary evil. The best solution
out of this is controlled usage of water for
irrigation purpose – a purpose successfully
fulfilled by this project.
23. Here is an animation showing the
working of the project…
24. The IC L293D tells the pump
motor to rotate
The Arduino decides
whether soil moisture is
above or below threshold
value
The soil moisture sensor
measures soil moisture
content
Information
is passed on
to the
motor driver
IC L293D
If moisture content is low, the
servo motor does its job and the
watering mechanism is activated
