Alectric Labs

Critter Cruiser

The Critter Cruiser, built out from the LEGO Mindstorms NXT kit, is a very simple vehicle that is capable of turning when needed. The Critter Cruiser has a frame, four wheels, and a motor, which is powered by a Mindbrick (controller unit) and connected to one wheel with an axle.
The motor spins at a constant speed and direction, and the Critter Cruiser is still able to turn when needed. This is possible because of the setup of the four wheels. The main part of the frame is a rectangular prism, and two of the wheels are mounted on the left and right sides of the frame. The third wheel is mounted in the front and is parallel to the first to wheels. The fourth wheel is mounted to the back and is perpendicular to first two wheels. Only three wheels are on the floor at a time. Normally, the Critter Cruiser moves forward because the parallel front wheel and the first two wheels are on the floor. When the Critter Cruiser moves into an obstacle, it tilts back, the front wheel lifts up, and the perpendicular back wheel makes contact with the floor for a short time forcing the vehicle to turn.

Pictures of the Critter Cruiser

The Critter Cruiser was originally a spinning box.
Right side view
Top view
Bottom view