This robot is really simple to make and then you can use this platform for other purposes.
Below is a video of the robot running on a track similar to one used in contests.
Step 1: The mechanics
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