[Rob]

Depending on your strategy, 3 wheel drive may be appropriate. The obvious problems with this concept are stability issues and less powered wheels on the ground. Advantages are higher manuverability and a lighter drivetrain than say a 6 wheel design.

In 1998 my team used a 3 wheel design, 2 powered wheels in the front and a caster in the middle back. In order to maintain stability we had .5" of ground clearance. In addition, we put small delrin skids on the bottom of the back corners in case they contacted the ground. As far as less powered wheels goes...We wanted to be quick and manuverable for that competition. While we had virtually no pushing power, we could escape from defensive machines using our manuverability.

My point is the following:
You should identify what qualities you want your drivetrain to have, and pick your design around them. List the advantages and disadvantages of each design. See if the advantages fir what you want, and see if you can come up with effective solutions for the disadvantages.

Remeber that people on your team will have vastly different ideas about what to do. Look to past robots from other teams for some inspiration on your ideas. Finally, compromise is sometimes the worst solution, you may have to give up on your idea, or convince others to commit to yours. It helps if you have some math or experiment results to back up the claims you make about your design ideas.

Good Luck,

Rob