LINE FOLLOWING ROBOT
The MOTORS:
The motors I used for this robot are 2 servomotors modified for speed. You can also use other motor if
it' s good enough... I didn't have any so I modded 2 servomotors.
HOW TO MOD THE SERVOMOTORS (look at the pictures)
1. Remove the four screws from the servo and take it all apart.
2. Remove the electronics keeping only the wires from the motor (I kept the other 3 wires from the
potentiometer but you don't have to).
3.Try to fit the gears except for one. I glued the big gear to the one beneath it so as to be high enogh to
"get out" of the case. It isn't exactly a rule for how to do this... various servos will have various gears so
you will need to try until you will find the best "combination".
4. Put everything toghether.
The BODY (look at the picture):
The base of the robot is made of PCB cutted to the properly size.
You will also need 5 screws:
2 for putting together the front and the base of the robot
one for lifting the sensors off the ground (you can use something else here, if you have)
2 for lifting and fixing the microcontroller PCB
Step 2The electronics
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The SENSORS:
I made my sensors using 5 SMD IR emiting diodes, 5 SMD phototransistors and 5 1k SMD resistors.
Between the phototransistor and the IR I put some black silicone so the IR light would not come
directly to the phototransistor. The PCB design is in the archive "line follower.rar". It is made in
PROTEUS, but I have a word document including all the PCB designs which can be printed on glossy
paper or Press and Peel, and then transfered to the PCB using the method of the iron.
The MICROCONTROLLER PCB:
The "heart" of this robot is an ATMEGA8 microcontroller which gets the information from the sensors
and drive the L293D motor controller.
Parts list:
1x 28-pin socket (for ATMEGA8)
1x 14-pin socket (for L293)
1x ATMEGA8 - You can also use an ATMEGA 168 or 328. The program is made in Arduino , so if
you have an arduino, you can program the microcontroller on it, then remove it from arduino and insert
it in this PCB. Also you can program this microcontroller via the 6 pins with an ISP.
1x L293D
1x 16MHz Crystal
2x 22pF (10-28pF)
1x LM7805
1x Push Button
1x 100nF
1x 100uF
1x 4.7 uF
6x LEDs
1x 1K resistor
1x 33R resistor
1x Break Away Header
1x Straight Female Header
1x SwitchWires
Also you will need one 4 AA battery holder.
Everything you need for making the microcontroller pcb and the sensors PCB is in the "line
follower.rar" archive. You will find the PCB design, and the schematics which are made in Proteus, but
are also available in the Word document.
Now all you have to do is take the soldering iron and start to solder all the parts.
After you' ve assembled the robot, you need to program the microcontroller. The program is made is
Arduino so you can upload it to Arduino and then put the microcontroller in this "motherboard". You
also have the HEX file for an ATMEGA8 using 16Mhz crystal.
Step 3Assembly
After everything is done... all you need to do is assembling the robot. You can watch a video of me
assembling it. Enjoy.