From: spike66 (spike66@attbi.com)
Date: Thu Nov 14 2002 - 22:38:33 MST
Emlyn O'regan wrote:
> Are you sure they can't stop hard? I got the impression that their
> parallel-wheels bely their tricky computerised nature.
Forget tricky computerized gazazzafratzes. Look at it
from the point of view of a mechanical engineer. Estimate
the position of the CG of the machine/rider combination and
look at the horizontal distance between that at the common
axle. Take the weight of the machine/rider combination,
multiply by that distance, and that is your maximum braking
torque. It doesn't matter what the computer is doing, you
cannot ever get that CG very far aft of the axle (especially
if one is a bony ass like me) which means regardless of the
compu-trickery, one cannot stop hard on a segway.
Another way to estimate your stopping power is to find
the cotangent of the angle between horizontal and the
line connecting the wheel contact patch and the machine/rider
combination. That is your stopping power in Gs.
Consider a good motorcycle brake: one can lock the front
wheel. I good rider can actually lift that back wheel
and hold it just above the ground. With its CG position
about 45 degrees upward and aft from the front wheel contact
patch, one can stop a bike at close to 1 G, at which time
the wheel locks and the cotangent model breaks down. Looks
to me like you would be lucky to get a third a G on a
segway.
HEY! that actually suggests another game we could do with
a segway: see who can stop one the hardest. I can imagine
some modifications like a switch that would defeat the
computerized brakes and enable a hand brake. One could
intentionally lean it back nearly horizontal and brake
hard enough to maintain that posture until the thing is
nearly stopped. {8^D Coooool! spike
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