Let sensors do the work:
Till now, we have made proximity
sensor, which can be used for obstacle detection or following a black line on
white surface (How and why? Ok, think about it. I will answer it a little bit
later). But I want to let you people know one thing that in higher level of
robotics, we don’t make sensors of our own (obviously you can make them for
your hobby and interest. But DON’T USE THEM in your robots as hand-made sensors
in most cases lack of accuracy and can make your robot prone to malfunction),
instead we buy them in ready-made version as they are pretty much
available in market in various price and accuracy range. We simply buy them and
put them in our robots.
Now, as we proceed to the making of
Line-follower Robot,let me answer some basic questions about Robotics.
What is a Robot?
The instruments with artificial
intelligence, which follow these 3 basic rules strictly can be called
"Robot".
1)A robot
may not injure a human being or, through inaction, allow a human being to come
to harm.
2)A robot must obey the
orders given it by human beings except where such orders would conflict with
the First Law.
3)A robot must protect
its own existence as long as such protection does not conflict with the First
or Second Laws.
These
are called "The Three Laws of Robotics",devised by Science Fiction
Author Isaac Asimov.
What sensors do in robotics?
What sensors do in robotics is that
they make your robots smarter and recognize more activities in their
surroundings and do something accordingly.
Let's make a Line-following Robot:
Let’s make it:
Requirements:-
1)IR sensor array of size 2(or simply
2 proximity sensors) or 3 or 5 or 8
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2)Arduino UNO or Genuino UNO
3)L298N(Recommended) or L293D motor
driver module
(Links-
4)2 wheeled or 4 wheeled chassis
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5) Motors - 2 or 4(according to your
chassis. Number of motors=Number of wheels)
(In many cases, when you buy chassis,you get motors in-built,so check it before buying extra motors)
6) Batteries or any other power source
to run motors.
7)Digital Multimeter (to check circuit,you may need a multimeter too)
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7)Digital Multimeter (to check circuit,you may need a multimeter too)
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For testing and experiment, you may
also need some white A1 paper and black tape to produce black line on white
surface.
Now,let's start making:
At first, make the robot body by assembling the robot chassis,
motors, wheels and clamps(if needed).
Then if your chassis is of two wheels, add the caster and ball
to your chassis and complete it.
If your chassis is of 4 wheels, connect two motors of left side
with each other in same sense of rotation(i.e. , they should rotate in the same
clockwise or anti-clockwise direction if connected to same voltage source in
parallel connection. You can easily check it and manipulate its connections if
needed)
So, now ,as the body of our robot is ready, let's add
sense(sensors) and brain( Microcontroller ...LOL...Don't get me wrong) to it.
In this step, I think you have got lots of
free space on the top of your chassis. Add an arduino, L298n motor driver (not L293d,if
its a 4-wheeler chassis. As, in practical case, we have seen L293d cannot take
too much load and it does not have in-built facility of PWM and its Power
efficiency is also low) and a small breadboard. Now add the IR sensor array in
the front of your robot and stick with a double tape. In this case, you should
ensure that the IR sensor array has got almost perfect central and horizontal
alignment. Also ensure that its height from the surface is not more than 1.5
inch(otherwise it can malfunction).
Now, our chassis-making part is fully completed. Let's get to
the circuitry part.
Make the following circuit.
Although the circuit diagram is quite clear, to avoid any
confusion, I am listing all the connections made above in a list:
1)Arduino GND-Battery(or other power source for driving
motors)(12V) GND-L298(or L293) Motor Driver GND
2)Arduino 5V-Motor Driver VCC-Enable 1- Enable 2
3)OUT 1,OUT 2-Right Motor
4)OUT 3,OUT 4-Left Motor
5)IN1-11
6)IN2-10
7)IN3-6
8)IN4-5
When you're done with all these stuffs, proceed to the coding
part. Only this coding part will be different for IR sensor array of size 8,5
and 2. When you will opened the code, you will find the Pin numbers are given
for IR sensor array. Connect the IR sensor array strictly according to that.
Also here, I am giving the details for connecting the IR sensor array.
For IR sensor array of size 8:
The pins are: {A0,A1,A2,A3,A4,A5,8,9} (Aligned from left to
right)
For IR sensor array of size 5:
The pins are: {A0,A1,A2,A3,A4} (Aligned from left to right)
For IR sensor array of size 3:
The pins are: {A0,A1,A2}
For IR sensor array of size 3:
The pins are: {A0,A1,A2}
For IR sensor array of size 2:
The pins are: {A0,A1} (Aligned from left to right)
So, finally we have completed the circuitry.
Now, let’s talk about the logic of the bot and after that we
shall move to the coding part.
Understanding the logic:
So, now we know, by the IR sensor array, we can recognize black
and white line, which also implies that we can detect the position of black
line with respect to the bot. So, now we have to think about various possible
positions of black line with respect to the bot and what our bot should do at
those situations.
Now, there is slight difference of logic for Bot with IR sensor
array of size 8 or 5 or 3 and Bot with 2 IR sensors. When the Bot is on the top of
the black line symmetrically or in centrally aligned position, for bot with 2
IR sensors, each sensor should sense white, while for the bots with IR sensor
array of size 8 and 5,only the central portion of the array sense black and
rest of the sensors sense white.
Position 1:
Position 2:
Position 3:
These were 3 basic positions for the
bot. Now, we should consider some more consequences:
1)What if the bot has moved away from
the line, i.e., each sensor senses white? In this case, we move our bot
backwards in expectation to get the black line again.
2)What if it has struck a T-shaped
joint or cross joint, i.e., all sensors sense black? In this case ,we can move
our bot in either left or right position.
Let's code it:
Now, let’s move to the coding part. On
the basis of the logic above, I have made three Arduino codes for your bot.
They can work with both 4 wheeled and 2 wheeled chassis and with both L293D
Motor Driver and L298N Motor Driver.
I have uploaded that Arduino codes in
a folder in Google Drive. You can easily download it.
Here is the link:
For those who are facing problem with Google Drive can download the files from this link too.
Link: http://www.mediafire.com/file/9ts45rdn4hgou0t/Line_follower_Robot%28Techie-rka.blogspot.in%29.zip
For those who are facing problem with Google Drive can download the files from this link too.
Link: http://www.mediafire.com/file/9ts45rdn4hgou0t/Line_follower_Robot%28Techie-rka.blogspot.in%29.zip
So, now as you have uploaded the code
to your Arduino, you have to calibrate your IR sensor array by adjusting each
potentiometer to detect black and white line. Once, you’re done with this, you
have completed making of the Line-follower Bot. Congratulations!!!
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