One day, young humanoid was looking at a picture of his project "Small Halftrack" and thought "I can do better!" So he made this. I have to agree with him, this one is better. Young humanoid implimented two light sensors to use as lights, an ultrasonic sensor and a tilt sensor to detect if the halftrack was being tilted. He also made the front of the robot look better and added a flip-up cover over the NXT.