Quote:
Originally Posted by akoscielski3
6WD chassis do not spin on the middle wheels and what ever else wheel/s it is on. They spin only on the Center wheels, and (if you picture this it will help) "rock" back and forth from the back and front wheels. Making the middle wheels the "Axis" for the turning. In 8WD it is a little different how it moves. It moves with the 4 center wheels, and eliminates the "rock". And makes it a little smoother chassis. But the rock may or may not be a problem depending on how much it rocks. For example this year a 6WD could have made your shot off, by the slightest little bit. 8WD might (most likely) Eliminate that problem.
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This is not always true, it depends on how the robot is designed. Actually, a well designed 6WD will
NOT rock while turning. unless it is being driven in a jerky manner. The ideal situation for a six wheel drive is to have the COG off-set to the front or to the back to eliminate the rocking effect since that would interfere with scoring and stuff. Typically, the COG is off-set to the rear so that it won't rock back during sudden accelerations and and to counter balance an arm if one is present, but there is no reason that the off-set couldn't be to the front if it provides some advantage specific to your design. This means that if all wheels are identical and the amount of drop is just enough that the set of wheel "in the air" has a negligible effect on driving, It will rotate about a point roughly mid-way between the two pair of wheels in contact with the floor. This is'n as noticeable as one would think, however and might seem like it is pivoting around the center wheels. In a few case, such as low traction corner wheels or a small enough drop that the "raised" wheels cause some scrub effects, the pivot will move closer to the center.