Holonomic Drive System Issues, Robot Drives Diagonally...

[AllenGregoryIV]

Originally Posted by Andrew Schuetze

I suppose one could set up a traditional 4 wheel tank steer with omniwheels all the way around and then add the center front and center rear wheels to add stafe and diagonal motions...

We tried this last year and I can say that it is extremely hard to get traction on all six wheels. If your robot is not perfectly level and balanced it will be extremely easy to lose traction and not be able to strafe. It gave us nothing but headaches. I am not saying it's impossible it just is very difficult (more so than the standard x configuration).

One thing to note about the plus configuration is that you will travel slower in the robots orthogonal directions then you would traveling at 45 degree angles. Omni wheeled holonomic robots gain velocity when all 4 wheels are powering them because each wheel actually has a velocity vector perpendicular to it's normal velocity. The whole robot is able to travel faster than any one wheel velocity. In a perfect world a 4 wheeled omni wheel holonomic platform with wheels 90 degrees apart will travel ~1.4 times faster than wheel velocity when traveling 45 degrees to any wheel.

You could just redesign the robot so the "front" is on one of the corners but that could make things tricky for manipulators. I agree that the plus would be harder to balance as well.