"Oh no not another Holonomic Drive" I hear you say. Afraid so.  It’s one of those ’must do’ projects so here is my attempt.

 I used the HiTechnic compass sensor so I would know which way the robot was facing and could then calculate how much power to apply to each motor to move or turn in the direction I wanted to go. The compass sensor is mounted well above the motors and brick to avoid interference.

 I originally started out with the brick above the base platform but the robot had a tendency to fall over if it suddenly changed direction or took off too fast. So I moved it below the base which also meant the compass sensor didn’t need to be so high.

 Worked pretty well as long as I didn’t try to make it go too fast in which case it tended to leave a trail of discarded wheels behind.

The frame around the compass sensor is just to protect it in case the robot falls over or hits something. 

 The video shows some of the things I was able to get it to do.