Wide drive base have additional benefit this year?

[Brad Voracek]

If we just decide to go with skid steering, would having a wider drive base be really difficult to turn? I imagine with the surface it'll be hard with skid steering already.. But what are the cons to a wider drive base? carrying that trailer already makes you longer, so your footprint is larger anyways...

Comments you all have?

[Nikhil Bajaj]

In skid-steering, wide drive bases are typically easier to turn--longer drive bases are harder to turn. This is why in previous years, six wheel drives with the middle wheel dropped have been very popular--teams have wanted to have the "front to back" direction of their robot be longer, which poses issues for skid-steering, so when you have the six wheels with the middle wheel dropped, the drive base tends to be on either the front four or the back four mainly, so that the "effective" drive base is wider relative to its length.

So a wider base will make it easier to turn. This is because of the geometry of the wheels and how the forces and torques are applied relative to the ground. If you look at industrial and construction skid-steer vehicles that have wheels (some Bobcats, etc. come to mind) the wheels look relatively close together so that the drive base is wider than it is long.

Cons of a wider drive base include the fact that if your robot is mostly moving forwards and backwards than having your drive base be say, ~38" wide and ~28" long means it is more likely to tip. Also, it becomes more challenging to fit something like an arm in the box if it has to be front to back (obviously, these issues can be designed around, but they make life more difficult!)

I don't know for sure how the interface between the trailer and the robot looks but maybe it could help you retain front/back stability by keeping you from falling. Also, it is harder to tip when there is less friction with the floor, so depending on your center of gravity it could be very advantageous from a turning standpoint to do a wide base.

Just some thoughts.

[Mike8519]

Fortunately, neither con applies to this game. It is very unlikely for a robot to tip this year and while arms CAN be built, they cannot extend outside the robots dimensions.

[Brad Voracek]

thanks Nikhil! That was helpful.

And yes, it does seem that the cons are minimal as tipping will be very hard with the trailer.. Hm. Good stuff to think about.

[Joe Ross]

This whitepaper gives the mathematical basis for being able to turn. http://www.chiefdelphi.com/media/papers/1443