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Subject: 
Re: Fishing for a tasty linkage/gearing/robotic building thread...
Newsgroups: 
lugnet.robotics
Date: 
Thu, 13 May 1999 13:44:30 GMT
Viewed: 
1524 times
  
In lugnet.robotics, lego-robotics@crynwr.com (Paul Speed) writes:
Or third, a synchro drive constrained to a ninety degree
throw.  This is simpler than the independent wheels since it doesn't
require an extra motor or complicated mechanism for raising and
lowering.  It is also easier than the rotation sensor version since
you may not necessarily have a rotation sensor.

...

If you constrain the rotation to be only between 0 and 90 degrees
then by running your rotations extra time you can be sure that you
are either 0 or 90 depending on the direction you turned.  Running
forward or reverse will then get you all four cardinal directions.


Agree. I didn't think of synchro drive and if you or any other suggested this
arrangement to solve this problem I missed that message. It's a very good
solution provided that you limit the rotation to 90 degrees with phisical
bounds to be sure you get very precise turns (as you properly suggest).

The most complicated part of this will be getting the drive train
snaked through whatever rotation assembly you have.  Most of the
synchro drives you will see examples of use the turntable pieces.
I do not have any of these so I have experimented with several
other linkages.  I won't go into them here... they are an
implementation detail.

The other hardest part is usually getting the rotation linked.  With
turntables and some chains it is easy.  Without either it is more
complicated if not impossible.  Since in this example we only need
90 degrees rotation then it should be possible to link them together
with beams.  This normally won't work because it limits the amount
of rotation.  In this case that is a good thing.

In one of my robotic vehicles (a 4WD rover) I used a mechanical solution to
provide traction power to the forward steering wheels. In that particular case
the rotation of the wheels was limited by the specific steering arrangement,
but as the main power travels ALONG the vertical rotation axle, I'm sure it
can be modified to allow 360 degrees turns.

There's a picture of it in my website (the veichle is called S4):

http://www.geocities.com/CapeCanaveral/Galaxy/9449/

I will experiment with this design a little bit this evening.  I've
been looking for an excuse to play and I think this fits the bill.

I'll do the same for the same reason :)
I've been tempted many times by the synchro drive but never started a serious
project.

Mario



Message is in Reply To:
  Re: Fishing for a tasty linkage/gearing/robotic building thread...
 
(...) Or third, a synchro drive constrained to a ninety degree throw. This is simpler than the independent wheels since it doesn't require an extra motor or complicated mechanism for raising and lowering. It is also easier than the rotation sensor (...) (25 years ago, 13-May-99, to lugnet.robotics)

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