My aim is to produce a line follower robot with a bump sensor
which can reverse if it goes off course.
Research: Line follower robots are most commonly produced to
take part in competitions. The purpose of the line follower robot is
to follow a line. The robot will only follow a line that is black
against a white background or a white line against a black background.
This is so that the sensors can distinguish a clear difference in
light and so the robot can trace and follow the line. From my research
I have decided to use infrared LED emitters (phototransistors). They
are fairly cheap but work relatively well.
To research into the project I was going to make I looked on the
internet to find other examples of the line follower robots. I found
many different variations and concentrated on the components used. I
looked into books and gathered information on how to assemble the
circuit on the breadboard and researched on how the components work.
I have researched on the type of amplifiers I could use for the line
follower. I will use an amplifier to increase the current as I am
using low voltage. I looked on the Maplins website (www.maplins.co.uk)
and decided to use the LM386 because it is suitable for low voltage
applications and it is relatively cheap.
* The robot has to be able to follow straight lines, curves and turn
* It has to follow a black line that is against a white background
* It must work using one 9V battery
* The robot must be able to reverse from any obstacle it hits
* It should be able to function on its own (No help needed to guide
* It should be small and light, easy to move and pick up if veered
* Should indicate what direction it will turn
Generation of possible solutions:
I could use 2 light dependant resistors to detect the difference in
light reflected from the line. It would react quite slowly
I could use two phototransistors which emit infrared beams onto the
line. When less light is detected on the phototransistors there is
less resistance thus allowing the motors to move.
My circuit had two designs combined. First is the line follower, which
detects light and moves according to the line, and the other part is a
bump sensor which when it stumbles across an obstacle it reverses,
this is because the switch had been pushed when it hits an obstacle.
I have decided to place two LEDs where the motors are, this is so that
the LEDs will indicate which direction it is turning towards.
The input is the phototransistors, they detect the light and depending
on how much light/resistance there is, activates the motors to move
which is the output.
Having the schematic completed I realized that my robot should be able
to travel in a straight line and turn around corners, including sharp
corners and reverse when it bumps into an obstacle. It will use an