Subject:
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Re: RSRA-2008
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Newsgroups:
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lugnet.technic
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Date:
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Mon, 18 Feb 2008 06:30:06 GMT
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Viewed:
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12690 times
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In lugnet.technic, Eric Sophie wrote:
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In preparation for our
RSRA Q&A / display
during Engineer’s Week at the
Liberty Science Center, for the FLL Expo,
(JCNJ), Ian and I have created a
simple ball return system.
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Ready for the show tomorrow, we did final testing today:
E.M.
We sought some expert advice, and here are the status notes:
We managed to run both arms. I would say the test is 90% successful. We left it
running for about 5 minutes. It stays working.
Current State:
1) Arm1 fails to pick up the ball because it cannot lower further, but can
drop the ball exactly right onto the top of the next station.
2) Arm2 can pick up the ball perfectly fine, but fails to drop off the ball
on the next tower because it does not turn enough.
Problems:
1) Motor difference:
The new arm (name it arm2) is “not” identical with the earlier tested arm (name
it arm1). Motor on the base of the arm1 seems to be very weak comparing to
arm2’s. Not only that, arm1’s base motor IS LOUD. Suggestion?
2) Off alignment between the Arms and drop towers:
Angle between Arm2’s base and the two ball stations is different from that
between Arm2’s base and the two ball stations.
3) Off alignment from Arm1 to ball box:
Arm2’s lowest point is exactly correct and has no problem picking up the ball.
However, the arm1 is still a bit too high from the ball box.
4) Event for ball arrival may be lost.
Possible Resolutions:
Prob1) Is the base modularized? If it is, we can switch motors to test.
Prob2) If physical adjustment is not desirable, we can simply make a separate
program for the arm2 to increase the rotation.
Prob3) I suspect a slight slant on the back side of the bottom which can hold up
the ball about 0.5cm higher. OR find out if arm1 can be adjusted to be like
arm2 so that it can be lowered as much as arm2 can.
Prob4) This is easy programming fix. Or, without the programming fix, a hack
is to simply slightly tap on the ball will trigger the event.
E.S.
So the arms behave differently due to several factors, ie.. friction, gear train
tension, and motor performance. Although built in an identical fashion, the two
arms can vary in expected results. Each joint must be examined and adjusted to
allow for optimal results.
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Message is in Reply To:
 | | Re: RSRA-2008
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| In preparation for our (URL) Q&A / display during Engineer's Week at the Liberty Science Center, for the FLL Expo, (JCNJ), Ian and I have created a simple ball return system. Basically a set of ramps that the RSRA can interact with. Whereas, as one (...) (17 years ago, 14-Feb-08, to lugnet.technic, FTX)
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