The finished robot:

A while back in late 2006 I got my hands on a Barbie Ride-On ATV. Its a small kids toy with enough torque to drive an 80lbs kid.
The moment I laid my eyes on that ride-on toy , I knew that I could hack it to make a robot.

Heres a picture of the ride-on toy before I got to hacking it :

There are a few problems with the ride-on toy when you want to use it on a robot.

1. There isn't any motor controller circuit to control the motor, its just a basic switch with no relays or MOSFETS

2. The steering wheel is hard to turn and you would need a really strong motor to turn the steering wheel on the toy.

3. Its pink and purple. Not many cool robots are pink and purple.

Here is how I solved those problems:

1. I made my own motor controller for the drive motor.

2. I chopped off the front half of the robot and added in a small R/C car steering mechanism.

3. I spray painted the thing black

I used the same motor controller from here : http://narobo.com/projects/electronics/pbr_controller/pbr_controller.html.
Instead of the Phidgets turning the relays on and off, I used a PIC microcontroller.

As for steering, I cut off the front portion of the Barbie ATV ( the side with the steering) with a hacksaw.
Then I cut off the steering portion of a cheap R/C car.

I basically just connected the drive motor section of the Barbie ATV to the steering section of the cheap R/C car.
I hooked up the cheap R/C car's motors to motor controller as well. And of course I spray painted it all black.

Here are some pics of the final robot :

and by far my favorite picture of the robot:

In the future I plan to use the Roboduino with this robot , maybe add some sensors and the like.