Omni Wheels can be used two different ways when driving :

One method is by having the wheels at different angles to each other.  A Tri wheel robot has the wheels 120 degrees apart.   A Quad wheeled robot has each wheel 90 degrees apart.  By changing the directions and speeds of the motors the omni-wheels will cause the robot to vector.  You can still turn if you wish, but if the robot is going straight forward and encounters an obstacle, no need to turn right - just drive/vector to the right!   The frames are laser cut aluminum and/or acrylic with predefined holes for OOPics, speed controllers, cameras, sensors, etc.  You can get the frames cut for three wheels or four.

The other method is to use the wheels in a standed 4WD Skid steer robot.  This robot is ideal for indoor and light duty outdoor activity. The ATRs steer using skid steering (differential steering). By varying the speed or direction of the wheels will allow the robot to turn. With high traction ATR tires this is difficult because the tires have to skid. Using the Omni tires allows easy turns because the wheels allow side slip. This kit should only be used on level ground. While the robot is plenty powerful to climb hills straight on, if the robot is sideways to a hill, it will side slip down the hill. We have loaded these robots up with over 100 lbs and it turned and drove very well. See our general ATR page for videos.