paper: MINIBOT acceleration solution

[Ether]

The desired engineering result for LogoMotion is to find the shaftDiameter which minimizes the time required to reach a specified height x. This can be done by using numerical methods on the solution x=f(time,shaftDiameter) presented in the paper. In the example spreadsheet, Excel's "Solver" does this quite easily with just a few iterations. A macro could be written to do the iterations, but it's almost as easy to adjust the shaftDiameter manually to converge on a close-enough solution.

A proposed method for characterizing friction is presented here. If anyone runs the test and finds that friction vs velocity is strongly nonlinear, then it would be worthwhile to explore finding solutions to the resulting nonlinear DE.