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Subject: 
Re: Working around the 3 output limitation
Newsgroups: 
lugnet.robotics
Date: 
Wed, 6 Jan 1999 14:14:20 GMT
Original-From: 
alex wetmore <{alex@phred}Spamcake{.org}>
Viewed: 
910 times
  
On Wed, 6 Jan 1999, S. Crawshaw wrote:
Someone mentioned a few days back that for a mobile robot you need to use
2 outputs for the motors. I reckon you can get around that on the proviso
that you *don't want to stop* one of the motors...

There are other ways to do this as well.  The most advanced is to think
of each motor output as being two outputs (forward and reverse).  If you
built devices so that they work with the motor going in only one direction
(possible for a claw, where it cycles between closed and open) then
this only requires half of an output.  You can share this with the
forward output on a robot (http://www.phred.org/~alex/lego has a
adder/subtractor platform based on Leo's design where would work well).
So with two motors you get four outputs:
1) cycle claw open/closed
2) forward
3) left
4) right

If you own one more motor then your two extra outputs are:
5) raise arm
6) lower arm.

A similar design could also be used for Lego's photobot, where the cyclic
operation is to press the shutter release on the camera.

There are various designs on the web for taking the output of one
motor and driving one of two output axles depending on the direction
of input.  Leo's lego (there is a link to it on my webpage) has a
nice one based on a worm gear which slides two a different output
axle depending on the direction of the motor.

Finally, my platform's can't be built with stock Mindstorms parts.
You'll need a 2nd differential (available in a gear service pack,
I think its #5229) and a 1x1 block with a hole in the middle (also
available in a service pack #5228, Small beams/plates).

alex

--
Did you check the web site first?: http://www.crynwr.com/lego-robotics



Message has 1 Reply:
  Re: Working around the 3 output limitation
 
snip (...) snip You may also want to check this page for a rotating and lifting arm that is controlled by one motor only: (URL) 'Asking directions' from menu Eric Brok Visit LEGO ON MY MIND: (URL) Control section: (URL) section: (URL) (25 years ago, 7-Jan-99, to lugnet.robotics)

Message is in Reply To:
  Working around the 3 output limitation
 
Someone mentioned a few days back that for a mobile robot you need to use 2 outputs for the motors. I reckon you can get around that on the proviso that you *don't want to stop* one of the motors... Make your chassis like a car, with rack-and-pinion (...) (25 years ago, 6-Jan-99, to lugnet.robotics)

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