Subject:
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Working around the 3 output limitation
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Newsgroups:
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lugnet.robotics
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Date:
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Wed, 6 Jan 1999 10:55:53 GMT
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Original-From:
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S. Crawshaw <SC10003@antispamENG.CAM.AC.UK>
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Viewed:
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894 times
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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 (or whatever) steering
on one pair of wheels, and drive the other pair of wheels from a motor
attached to a standard battery box. If you've bought 8735 to get a 3rd
motor you'll have an otherwise useless battery box, so why not use it?
For a slow-moving robot (for example one which needs to pick up or carry a
heavy load), or for a combat robot, the continuously moving assumption is
quite reasonable. Another obvious situation would be if you're using a
pneumatic compressor and tank; off-hand I can't think of more, but I'm
sure there are others.
So, for example, you could make a robot with one output for steering, one
for an arm and the third for a gripper. (This, of course, assumes you've
got enough motors/actuators...)
Speaking of motors: here in the UK it seems the cheapest way to get a 3rd
motor is to buy the cheapest of the motorised ZNAP kits, which is 14 UKP
(about 20 USD) It doesn't have all the extra gear wheels etc that you'd
find in the 8735 kit, but is quite a lot cheaper.
Stuart
--
Did you check the web site first?: http://www.crynwr.com/lego-robotics
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Message has 3 Replies:
 | | Re: Working around the 3 output limitation
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| (...) 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, (...) (25 years ago, 6-Jan-99, to lugnet.robotics)
| | | Re: Working around the 3 output limitation
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| (...) Another option is to use "half motors" -- ie, if you are using 360 degree 4-wheel steering and driving all four wheels, those drive wheels never need to go in reverse. You can use a differential and two ratchets to separate the forward motion (...) (25 years ago, 6-Jan-99, to lugnet.robotics)
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Message is in Reply To:
| | Re: RCX Limitations, griping, etc. :)
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| (...) Ahhhh....but alas my friend, that is where the challenge lies. Hey...the Apollo missions had less to work with. :) (...) Well...the RCX *is* the commercialized version of the MIT work. (...) Yep, I agree. (...) ...and just a tad too large to (...) (25 years ago, 6-Jan-99, to lugnet.robotics)
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