This is a robot vehicle I made with the Lego WeDo kit. You can see a video of it in action here: https://vimeo.com/130042301 If you click the green flag, it will drive forward until it approaches an obstacle. It will then reverse and turn to the right. After 5 seconds, so long as the obstacle is out of range of the distance sensor, it will start driving forward again. It can also be controlled manually using the up and down arrows. The key to this model is the back wheel (made from a cog as the WeDo set only comes with two proper wheels). The cog can pivot between the yellow block at the back-right, and the yellow bar in front of it. When the vehicle moves forward, the cog wheel moves to the back position, where it is aligned with the front wheels, and so the vehicle moves in a straight line. When the vehicle reverses, the cog wheel swings forwards and to the left, so steering the vehicle to the right. Because the cog wheel doesn’t work very well on a smooth surface, this vehicle works best on a rougher surface, such as a carpet or a cloth. You can see more photos of this model stored inside the project as backdrops.
A Komaba original. The straight-forwards / reverse-turn mechanism is based on the system used by a sonic-controlled car I had as a kid.
