Quote:
Originally Posted by Oblarg
Out of curiosity, have you got any data on the effect of the stacked wheels vs. single wheels on frictional forces?
Also, is there any difference in the wear characteristics when you stack the wheels like that? I'd imagine it'd get expensive replacing all of those if they wore as fast as single versa-wheels.
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Each wheel is supporting less weight so the wheels will wear slower individually (but you have to replace more wheels when they do wear out). The eventual cost of replacing wheels comes out to almost exactly the same. Pretend 4 wheels wear out after ~20 matches. That means that 8 wheels stacked in the same configuration will likely wear out after about ~40 matches. After 80 matches both drivetrains have used 16 total wheels.
Calculating frictional forces between non uniform, non smooth surfaces can be difficult because they don't operate the same way that regular smooth surfaces do as is taught in basic newtonian physics. According to what you learned in those classes the surface area of an object shouldn't change it's frictional forces. However, in practice (you can test this yourself) having more rubber in contact with the floor can actually increase your drivetrain traction contradictory to what newtonian physics tells you. I'm sure someone on here can tell you how to calculate correct frictional forces between non smooth surfaces but the best way to find out is just to test it. Drive your robot against a wall and see how much current the motors draw before your wheels start to slip.