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Subject: 
Rocker-boogie suspension model
Newsgroups: 
lugnet.build, lugnet.robotics
Date: 
Sun, 18 Oct 1998 21:45:28 GMT
Viewed: 
1422 times
  
Here is a model that incorporates a 6 wheel drive, independent and un-sprung
suspension system.  This was modeled after the rocker-boogie suspension on
Sojourner.

As I mention below, this is quick to build and real fun to watch climb
across your Lego table.  Build it and let me know!  There are one motor
instructions below if you only have one geared motor.

I tried to make it as sleek and piece efficient as possible.  The real model
uses sm. balloon tires... but the LDraw parts don't exist yet so med. space
wheels were substituted.  Balloon tires climb the best!

I have posted a LDraw file in Lugnet.cad.dat, and a picture (47,789 bytes)
at http://members.home.net/ourcreations/pictures.htm

Thanks to Randy  Anchikoski for posting my rendering on his page.

LINC

Excerpts from design notes in boogie.dat:

0 A major design feature of this model is the dual use of the axles.
0 Axles that act as pivots for the suspension system, are also
0 components of the drive system. This maintains an un-sprung suspension
0 system. If the drive axle differed from the pivot axle, unless the
0 V-belts of the front two wheels are equal, the wheel support would
0 rotate to equal the V-belt forces. The wheels would try to maintain
0 this position, and thus become 'sprung'.
0
0 This model is a great model to watch in action. Inside, take a rug/
0 towel, and shape a 'moonscape'. I thought that the two motors might
0 allow crude 'tank' steering, but it doesn't (it might on looser dirt).
0 I guess that's why the Sojourner has wheels that steer. :) Lowering
0 the center of gravity could be addressed; however, the model does
0 surprisingly well at remaining upright at 45 degrees to the side, and
0 +45 degrees front to back. It sometimes climbs abrupt objects better
0 if going backwards.
0
0 The original version used only one motor. A one motor design can be
0 achieved by removing one motor assembly and the key central friction
0 peg, and then inserting a 12-stud axle between the two rocker-
0 boogie supports. The motor will rotate with only one of the rocker-
0 boogie supports, and drive the 12-stud axle.
0
0 placing a platform between the two motors is quite easy... perhaps some
0 mini-fig modelers can get a vehicle out of this one. A RCX might sling
0 nicely between the motors as well.



Message has 3 Replies:
  Re: Rocker-boogie suspension model
 
(...) office, I think... Can you describe how to set up the motors? It's not clear in the picture, and I don't want to have to dig up LDraw to figure it out. Thanks, -Kekoa (26 years ago, 18-Oct-98, to lugnet.build, lugnet.robotics)
  Re: Rocker-boogie suspension model
 
Linc Smith wrote in message ... (...) Yahhhh! Real building. Can't wait to try it myself. I might use balloon tires... Cheers, Ralph Hempel - P.Eng ---...--- The train stops at the train station, The bus stops at the bus station, So why am I sitting (...) (26 years ago, 19-Oct-98, to lugnet.build, lugnet.robotics)
  Re: Rocker-boogie suspension model
 
Hey, that is one cool model. It took me a while to figure out how to build from the instructions included, but it is worth it! If there is interest, I could take pictures of the rocker-boogie with my digital camera and post pictures on my web page. (...) (26 years ago, 23-Oct-98, to lugnet.build, lugnet.robotics)

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