Here are some examples of basic chassis designs for a mobile robot.

This design uses two motors, one on either side of the robot. The wheels are connected to the motors through gears. To turn the robot, one motor is driven forward and the other motor is driven backwards. Different combinations of gears can be used.

Here is a chassis design that uses belts and pulleys to drive two wheels.

This chassis design is a 4-wheel drive belt and pulley mechanism.

This chassis uses just one motor to power both of the wheels. The motor powers a differential, which allows the wheels to turn at different speeds. This one-motor chassis design is very useful if you need another motor for a different robot function.

Here is a chassis that uses worm gears. This chassis is very strong, but very slow. Belts and pulleys are used on the motors. This is good in case the robot gets stuck. The belts will slip and not stall the motor. Use treads on this chassis for a very powerful tank robot.

See also: Gears, Differential, Worm Gear, Belts and Pulleys