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[DPRG] segway

Subject: [DPRG] segway
From: futurebots fuboco at bellsouth.net
Date: Tue Dec 3 20:35:01 CST 2002

Chuck McManis wrote:
> 
> At 05:39 PM 12/3/02 -0600, cbrenizer wrote:
> ><I meant to send this to the entire list, too>
> >I had wondered if a third wheel device costing 3 or 4 hundred dollars
> >would have happier customers than the multi-thousand dollar segway (I
> >know I'd be happier paying less and it probably wouldn't need much
> >electronics, since it wouldn't have to be self balancing)
> 
> This is a common mis-perception. Two wheel, three wheel, or 18 wheel, you
> have to deal with torque of a vertical human body. The value proposition of
> the Segway is not about balance, its about inertial mass management.
> 
> Consider a human standing on a "trolley" (you can imagine any number of
> wheels on it) moving forward at a velocity "V" When you decelerate your
> momentum (mV) is converted into a torque that is related to how far your
> center of mass is from the trolley. The harder you decelerate, the more
> torque you experience and the more likely you are to fly off the thing.
> 
> The Segway, manages your momentum by changing the torque angle inversely
> proportional to your rate of deceleration (that is to say you "lean back")
> which causes your relative torque moment to be 0 (or put another way it
> keeps your angular momentum 0) so that you perceive the declaration as
> increased acceleration along your vertical axis. This translates in a shear
> force on the wheels and ground.
> 
> Basically you don't fly over the handle bars because you are never being
> pushed toward them and conversely when it accelerates you don't fall off
> the back.
> 
> Now you could put a tilting platform on your trolley and have it do this
> compensation (think of a coffee cup holder for your that uses gimbals to
> keep the cup level in the face of changing accelerations.)
> 
> So to completely replace what the Segway does on a multiwheel vehicle is
> you would need to first have a platform that could roll over the kinds of
> terrain that a Segway does and can turn in place (this is essential for
> navigating human targeted environments), and then you need a hydraulic
> platform (or a fast electromechanical one) that could keep your inertial
> acceleration vector vertical in real time.
> 
> The neat thing about the Segway is that it does both of these with exactly
> two motors.
> 
> --Chuck
> 
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I think walking would be much better for us..

Have fun with you robots..
Dan Mathias  
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