to view all the posts i did on this robot, please check my g+ profile,
my original intention was to build a line follower robot, until my wife's household chore caught my attention. from then my focus was on creating a robot similar to roomba, minus the vacuum. :]
the original design was a bit of a bulky wiring, but it worked well, running only on a single 9V battery to power the arduino uno, motor shield, and an ir sensor. then i read through some posts that this was a bad idea so i had to split powers for the arduino and the motor shield, and the mop section also got gave up after bumping several times at high speeds.
the 2nd design had a flaw which i didn't think through. i placed all components on top of a flat plastic plate which meant that there was more surface area in contact with the ground. this meant more force from the motors to move it. failed.
these are the parts i collected to make this robot: