Let's Make Robots!

Question about ground (first robot) and dual H bridge

Hi everybody,

I finally built my first robot, loosely based on the start here tutorial and obviously I have tons of question.

This is the motor driver I am using : http://www.geekonfire.com/wiki/index.php?title=Dual_H-Bridge_Motor_Driver

and in the examples the ground of the motor driver is not connected to the arduino's ground.