This instructable will introduce some of the simplest and most elegant robotics conepts I have ever seen. The concept came from a book called Vehicles : experiments in synthetic psycology by a guy named Valentino Braitenberg, and appropriately, robots based off of this concept have come to be known as braitenberg vehicles.
These braitenberg vehicles can be built using nothing but a pair of motos, a pair of sensors, a battery, and a power opp amp, but they are able to move in ways that seem so biological that braitenberg chose to attribute them to emotions.
"Robots that emote? this is not possilbe" you say, and you're probably right, but I've made a short video to demonstrate the robots and show you what I mean.