6WD Chassis Stiffness vs. Maneuverability

[IKE]

Not sure why this didn't occur to me earlier, but I think I can vocalize it better now. We have danced around the concepts, but some simple assumptions show a lot.

1. Assume an inifinitely stiff drop center 6WD chassis with 6 traction wheels. As long as the drop is more than the carpet compression, only 4 wheels can touch the ground at a time. More importantly, the middlewheel will be on the round and then only the front, or only the back can touch. This means you can use the above whitepaper to analyze whether or not your bot will turn well.

2. Assume now a noodle chassis. Same base geometry as the above chassis, but it is so soft that all wheels touch even though the center is dropped. This will require a lot more torque to turn because of all the additional lateral grip.

Now to answer my torsional stiffness question.
3. Assume that the rails of the chassis are very stiff, but connected with a swivel. While only two wheels of each rail section can contact the ground, opposite corners can contact during a spin manuever. If you sum the moments, you will find that this will require about double the torque of case 1 to spin(turn).

Case 3 is probably the most similar set up as what Team 33 ran last year. The sheet metal construction had relatively stiff rail and axle systems, but the stringers between the rails sections allowed for a lot of torsional flexibility.