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Unread 13-12-2015, 17:32
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I am Dave! Yognaut
AKA: Brian Bray
FRC #1296 (Full Metal Jackets)
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Re: Drive Wheel Sizes

Quote:
Originally Posted by Joe Ross View Post
Have you quantified the efect of the rotational inertia of the wheels vs moving a 150 lb robot?
Assuming a 150lb robot traveling at 18ft/s (5.5 m/s) with 6WD configuration
I calculated the kinetic energies of 4 different wheels based on these assumptions
I did not do anything pertaining to gears though.
Colson wheel is uniform cylinder of radius 2"
Traction wheels are uniform cylinders combined with thin rings with radii 2, 3, 4"
All wheels calculated were 1.5" wide and I used masses given on the Vexpro website

The kinetic energies stored in all 6 wheels of the 6wd combined are
4" Colson - 21.7 J
4" Traction - 22.7 J
6" Traction - 35.6 J
8" Traction - 43.3 J
150lb Robot - 1028.5 J

Why did I use kinetic energy you might ask? well because ultimately your motors are imparting energy into the system at some rate. The motors must expend the listed amount of energy (plus all the losses reaching that energy) for the robot to reach that speed.

To be fair, larger gearing (well, more stages at least) will accrue more loss that wasn't accounted for, but I'm not going to draw any conclusions.
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