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Subject: 
Re: Tri-star wheels [was: Re: [Woefully off topic] Feel the .sig Luke...]
Newsgroups: 
lugnet.robotics
Date: 
Fri, 3 Mar 2000 14:33:24 GMT
Original-From: 
Brian B. Alano <alano@SPAMLESSkiva.net>
Viewed: 
886 times
  
I briefly experimented with a stair-sized tri-star wheel. I discovered it would take
a lot of power and a lot of Legos to make it work (the Tri-wheel radius must be
greater or equal to the height of the stair's riser plus the radius of each tyre and
the vehicle's body length needs to be at least twice the Tri-star wheel radius to
keep it stable and to keep the front and back wheels from interfering with each
other) I didn't completely abandon the idea, but I *did* decide it would be easier
to have two robots, one on each level of my house, rather than one robot which can
climb stairs.

Oh, I guess if you don't *have* back wheels you eliminate the need for a lot of
Legos, but you'll still have to find a way to get enough leverage to climb.

Doug Weathers wrote:

in article 85256896.00771B64.00@aamta02.avid.com, lego-robotics@crynwr.com
at lego-robotics@crynwr.com wrote on 3/2/00 1:38 PM:


I'm thinking about how to design a machine that can climb real-live household
stairs - as
well as move about flat surfaces. I've seen designs for robots that can climb
obstacles, but
not as big as a step. I'm thinking of something along the lines of a six
wheeled
robot.
Two Y shaped ferris wheel thingys with a wheel at the end of each spoke (two
wheels in
contact with the ground at any one time). When the robot detects a stair or
obstacle, it
could shift its weight and rotate the Y forward. Has anyone seen anything like
this ?

Critically, I think the centre of gravity must be higher than the step for
this
to work.

bad ascii art:

1    O         2 O         3  O
     |            \           |
     O   ___       O--O       O
    / \ |          | ___     / \
   O   O|          O|       O   O
robot   obstacle          -------

-Simon



Actually, that's a very nice piece of ascii art describing something called
the tri-star wheel.  I saw my first example of this on a vehicle from a
cheesy movie called "Damnation Alley", adapted from a story by Roger
Zelazny.  The vehicle was real (except for the missile launcher :).  It
steered by bending in the middle, and at one point was seen crossing a lake
- the tri-star wheels acted like paddlewheels.

I've been interested in building one for some time but have never actually
sat down and tried it yet.  My current robot project has four-wheel drive
and steers by bending in the middle, so if I just stick tri-star wheels on
it....

I also recall seeing a baby stroller with tri-star wheels.  You could just
roll it right over curbs and the like.

There were a couple of web sites that discussed creating tri-star wheels
using Lego, but they both seem to be gone and I can't find where they might
have gone.  Wait...  there's one of them!

http://www.visi.com/~dc/

Hope this helps,

Doug

--
Doug Weathers, http://www.rdrop.com/~dougw
Portland, Oregon, USA
Don't spam me - I know how to use http://www.spamcop.net
"On a clear disk you can seek forever"

--
______________________
You hear, O LORD, the desire of the afflicted; you encourage them, and you listen to
their cry  --Psalms 10:17



Message has 1 Reply:
  Re: Tri-star wheels [was: Re: [Woefully off topic] Feel the .sig Luke...]
 
There's a different kind of stair-climber on LEGO Mindstorm's site, but you'll have to look it up. It was a few months ago. It drives up to a stair, stops, climbs a ladder (not really, it's a rack) and once on the upper level, brings the ladder back (...) (25 years ago, 3-Mar-00, to lugnet.robotics)

Message is in Reply To:
  Tri-star wheels [was: Re: [Woefully off topic] Feel the .sig Luke...]
 
in article 85256896.00771B64.00....avid.com, lego-robotics@crynwr.com at lego-robotics@crynwr.com wrote on 3/2/00 1:38 PM: (...) Actually, that's a very nice piece of ascii art describing something called the tri-star wheel. I saw my first example (...) (25 years ago, 3-Mar-00, to lugnet.robotics)

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