6WD Pros and Cons

[Daniel_LaFleur]

Originally Posted by M. Krass

In the instances above, you're assuming a different center of mass in each case. If the weight is distributed evenly across the robots, the center of mass will be in the center of the robot and it will, thus, turn about that point.

You are correct (as usual ), if the weight is evenly distributed the robot will "hop" and rotate around the CoM. I've generally set our weight distribution to 2/3 weight over the rear axle and only 1/3 weight over the front axle. That allows the robot to provide enough force to have the front wheels break free (sidewards) allowing the robot to rotate around the rear axle.

And by shortening the wheelbase (by driving 36" wide and 28" long, giving us a wheelbase of ~19"), having a high CoF (~1.3, adjustable because they are pneumatic tires) and providing plenty of torque (4 small Cim ... 1 per wheel ... with 16:1 reduction) we've been able to turn without difficulty, been able to push almost anyone, and have been very difficult to be pushed or turned by others (including 6 and 8WD opponents).

** Note: I use the term axle, but we usually power each tire individually and there is no contiguous (sp?) axle across the rear (or front) 2 tires.**