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Subject: 
Re: Casters
Newsgroups: 
lugnet.robotics
Date: 
Tue, 22 Aug 2000 18:00:11 GMT
Viewed: 
490 times
  
It might be thus:  When the motors engage, there's some torque in the body
that would tend to lift the nose of the vehicle up (think of a dragster, how
it pops a wheelie under acceleration).  Thus, when under acceleration, the
front of the vehicle is lifted slightly, loosening up the friction in the
caster joint and allowing it to swivel more easily.

With the caster in the back, the torque from the rotation of the motors puts
MORE pressure on the caster, making the friction forces higher, and thus
making the caster turn more slowly and less precisely.

Adrian
--
www.brickfrenzy.com

In lugnet.robotics, "Wilcox, Doug" <Doug.Wilcox@iMcKesson.com> writes:
Can anyone explain to me why front-mounted casters, with the powered wheels
toward the back of the robot (see photo at
www.wordsmithdigital.com/mindstorms/diaries.htm ), stay in alignment better
than rear-mounted casters with the wheels in front? I can't quite grok it.

Doug Wilcox
Senior Web Developer
iMcKesson Provider Solutions Group-Needham
160 Gould Street, Suite 130
Needham, MA 02494-2308
Phone: 781.453.2900 x 237
Fax: 781.455.7990
e-mail: Doug.Wilcox@iMcKesson.com
http://www.imckesson.com

"You see, I had this space suit. How it happened was like this ..."
(Opening lines from Robert A. Heinlein's Have Space Suit-Will Travel)



Message has 1 Reply:
  Re: Casters
 
(...) Yes, that's my impression too. From the pictures it seems that the caster joint is made from a single plate with holes, which creates a lot of friction because the axle cants(?) under weight. A better design would be to use two plates at some (...) (24 years ago, 23-Aug-00, to lugnet.robotics)

Message is in Reply To:
  Casters
 
Can anyone explain to me why front-mounted casters, with the powered wheels toward the back of the robot (see photo at www.wordsmithdigital...iaries.htm ), stay in alignment better than rear-mounted casters with the wheels in front? I can't quite (...) (24 years ago, 22-Aug-00, to lugnet.robotics)

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