paper: MINIBOT acceleration solution

[boomergeek]

Originally Posted by Ether

For physics and/or math students who may be interested, I just posted a short write-up showing how to setup and solve the differential equation for the MINIBOT accelerating from a dead stop up the pole. An analytical solution is given so you can just plug numbers in using a calculator (if you have the patience), or better yet a spreadsheet.

The model ignores friction, which may be a significant factor, but the physics (and math) is nonetheless interesting and useful for gaining insight and rough approximation.

http://www.chiefdelphi.com/media/papers/2470

Great stuff! I was a bit disconcerted that it indicated that our minibot should be twice as fast as we are measuring and it instigated us to try to determine the largest factor not accounted for by your model.

I'm coming to the POV that it is probably rolling resistance.
http://www.real-world-physics-proble...esistance.html

(force friction) = (normal force) * ( the horizontal distance representing the wheel deformation) / (undeformed radius of the wheel)

We are going to try more rigid wheels with less deformation (thinner tubing)

The normal force is approximately twice the minibot weight and the deformation impacts two wheels, and the radius is very small for direct drive.

I'm curious if others with direct drive and small diameter wheels might have similar issues or have already figured out how to get results that match Ether's fine model.