A group of friends and I when we were 15 competed in a UK-wide competition to build a robot with sonar and touch sensors to navigate through a field of obstacles. The winner was the fastest average. Our robot only travelled in bent lines, and turned when it detected an obstacle infront of it. We had our three tries, the first two taking perhaps 30 seconds. The third time we twisted it slightly on its start position, and without stopping it followed a curve through the whole course, in about 3 seconds. Unfortunately we weren't even mentioned in the runners up :L