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[DPRG] segway

Subject: [DPRG] segway
From: David Peterson robodave1 at attbi.com
Date: Tue Dec 3 10:07:01 CST 2002

  5 gyros and 2 tilt sensors in a custom assembly. Probably also used in
their iBot mobility system, though no press stating such yet. I believe the
CRS-03 may be the 5 units used. Not sure what tilt sensor or accelerometer.
   Heard it from another fellow who is also developing a balancing robot,
using their CRS-04 gyro in a balancing robot. This unit may be used in one
of the Futaba model helicopter heading hold gyro units.  Looks like Dave has
started a trend.
   And Dave.. in the words of Sylvester the cat ... you're dishpicable... I
wanna play with a Segway! : )

----- Original Message -----
>From: "Earl Bollinger" <earlwbollinger at attbi.com>
To: "David P. Anderson" <dpa at io.isem.smu.edu>; <dprglist at dprg.org>
Sent: Tuesday, December 03, 2002 6:17 AM
Subject: RE: [DPRG] segway

> Were you able to figure out what gyros they were using?
> -----Original Message-----
> From: dprglist-admin at dprg.org [mailto:dprglist-admin at dprg.org]On Behalf
> Of David P. Anderson
> Sent: Sunday, December 01, 2002 12:59 PM
> To: dprglist at dprg.org
> Subject: [DPRG] segway
> Howdy
> A fellow came by the university last week with a couple of Segway
> Human Transport Vehicles and I had a chance to play with one and
> ride around a bit, both indoors and outdoors.
> For anyone that's missed it, this is a two-wheeled dynamically balanced
> platform very much like my two-wheeled robot nBot.  After playing
> with it a bit I have the following observations:
> 1.  It's a LOT of fun to ride.   The balance is very stable and like
> with nBot you make it move simply by leaning fore and aft a small amount.
> Steering is controlled with a motorcycle style left-handed grip, counter-
> clockwise for right and clockwise for left.  It can spin in place and
> we easily maneuvered around the halls in the science building, into
> folks offices and around their desks, etc.
> 2. Top speed is about 12 mph, which seemed pretty fast indoors and pretty
> slow outdoors, easily outpaced by folks on bicycles.  It handled curbs and
> ramps with no problem, and had no tendency to roll downhill unless you
> expressly leaned in that direction.  Very maneuverable.
> 3. Turning at any speed is a little counter-intuitive, as it does not
> lean into the turn it almost feels like you are leaning out of the turn!
> The fix is to lean your body into the turn, like on a four-wheeler or
> as racers on motorcycles with sidecars do .  A bit awkward.
> On the other hand, you can drive it fore and aft (no turning) without
> touching the handlebars at all, just with your feet, with your hands
> in your pockets.  It's that stable.
> 4. Of the two models we had to play with, one would balance by itself
> with no rider (though we weren't allow to ride that one) and it had
> saddle bags with books and batteries, ballast I suspect.  The other
> had no "kick stand" mode and would not balance without the inverted-
> pendulum weight of the human.  The one which would balance unattended
> was not critically damped, and a small shove left it oscillating for
> a long period as it slowly regained equilibrium.  The fellow who brought
> them for demo got quite nervous when I started shoving it around.
> 5. The salesman (he insisted he was not, only "evaluating" them) was a
> little
> defensive on the practical application of these vehicles, and had no good
> answers to the questions posed him by the physics and geology faculty (all
> of whom had a great time riding!) such as "why this rather than walking?"
> and "why this rather than a bicycle or traditional electric scooter?"
> is for $6000-$9000 I not sure there are good answers to those questions.
> (If I was trying to sell them, I would concentrate on the sport market,
> skateboards and surfboards and dirtbikes and sailboats, rather than trying
> to convince folks this was a practical replacement for cars or motorcycles
> or bicycles or walking).
> 6. However, that being said, I am more convinced than ever that this is
> OPTIMAL PLATFORM FOR A ROBOT!  In concept at least if not in this
> incarnation.  I believe our (robot builders') application for this
> technology
> is extremely natural and logical, more so perhaps than for human
> 7. Most of us are already building three wheel robots, with two drive
> and a tailwheel which is really only there for balance, and causes certain
> manuvering problems.  The three wheel design is not really all that
> especially on inclines and irregular surfaces, and is fairly miserable
> outdoors.
> Making it more stable involves extended the tailwheel far behind the drive
> wheels, and then it tends to run into things when the robot tries to spin
> place.  Four wheels are much more stable than three, and allow
> suspensions and such not possible with three wheels, but gives up the
> ability
> to spin in place (0 turning radius) without lots of complex technology.
> went to a very complex 6 wheels with rocker boogies and independently
> steering
> wheels on their Mars rover to address these problems.  Quite complex.
> 8. Military/contruction vehicles solve this problem with tank treads, but
> these are
> very inefficent, hi-friction and hi-energy consumption.  And because they
> require
> slippage in order to turn, it prevents the use of wheel odometry for
> location and
> navigation, as well as causes problems indoors with loose carpets and
> on the floor.  Treaded vehicles are also very difficult to maneuver at
> speed.
> Toy manufacturers in the 90s tried to start a class of racing tanks, but
> found
> the problems of steering at high-speed made it impractical.
> For these and other reasons the two-wheel differential drive with
> free-castering
> tailwheel has become the most common robot platform among hobby builders.
> The
> addition of an inertial measurement sensor and a little software can get
> of the
> tail wheel without changing the rest of the design, and _greatly_
> the
> stability, off-road capability, maneuvering, etc.  Hence my increasing
> confidence
> that the two-wheel dynamic balancing technology is a natural platform for
> robots.
> Plus it gets extremely high marks on the Scale of Absolute Coolness.
> I shot some photos of the Segway and nBot side-by-side in the hallway of
> Heroy building, for comparison, and put them on
> http://www.geology.smu.edu/~dpa-www/robo/nbot
> scroll down towards the bottom of the page.
> regards,
> dpa
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