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Unread 28-06-2003, 11:01
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Matt Leese Matt Leese is offline
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Quote:
Originally posted by D.Fahringer
The lower the CG the easier it is to remain upright it seems to me. The fact that I can stand on the KnightKrawler without turning it on displays some inherent stability. The students and I have a little trick we do on it where we set the speed and a mild turn and then let go of the controls....(the "No Hander Meander").

Take a base where you stand above the axles of the wheels
and one where you stand below and try to balance....no contest!
If the wheels are free to turn the first one will get you in trouble right away!

I am keeping in mind that a yard stick is easier to balance on my hand than a 6 inch ruler and the yard stick's CG is further from my hand but I feel that is just a reaction time matter.

Anyone else have thoughts about this? It is interesting!
It's going to be easier to balance something with a higher CG (within reason). They physics behind it are fairly simple. If you have an inverted pendulum (which this is the same thing as), you can consider all of the weight of the pendulum to be at the CG. Now, in order to balance the pendulum, you have to keep the CG in roughly the same place. Because of this, you move the bottom of the pendulum back and forth. Now, if you have a higher CG, you can move the bottom of the pendulum a greater distance while keeping the CG in the same place. This means that you can have less precision in your movements. It gives time for the control loop to settle down to a more stable state. So that's why a yard stick is easier to balance than a ruler.

Matt
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