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Unread 20-03-2014, 22:44
TheHolyHades1 TheHolyHades1 is offline
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Pistons not extending fast enough?

Hello. Today we conducted a test for a pneumatic system which we are looking to add to the robot before the next competition, but we were met with a rather unsuccessful attempt at shooting a ball. I'm posting here to hopefully get some suggestions to improve the design and/or point out any fundamental flaws with the system.

The tanks were charged at around 90 PSI (the working end pressure guage was displaying about 70 PSI, this needs to be reduced). The setup was constructed sort of arbitrarily, in that I didn't make any exact measurements to emulate the robot in any particular way. This was set up more as a proof of concept, and unfortunately, the proof of concept seems to have failed.

Differences from the design that'll go on the robot (see pictures):

1. When fully retracted the pistons are attached so that the ramp is upright; this is opposite of what the actual design is at the moment, whereby the pistons will be attached so that the ramp will extend from about its current 30 degrees below horizontal to approximately 45 degrees above horizontal (or as close as possible, that being the idea angle for kinematics. This could certainly change if/when I get around to reading some of the more complex analysis that has been done on the physics of the ball). To account for this, we angled the setup (as demonstrated in the videos), though I'm not sure how closely we replicated the movement.

2. The ramp we're using is made of wood and lacks the metal side rails that are on the ramp currently. This would have made it easier to launch the ball as it is significantly lighter.

3. The hinges are strap hinges instead of piano hinges as are currently supporting the ramp on the robot, though I doubt that matters much.

4. We were shooting at a PSI that was slightly higher than the allowed 60 PSI (70); at least, that's what our guage read.

That being said, I think that this test should have at least proved to some degree whether the concept would work. However, after doing it, I found that the ramp rotates much too slowly to be able to do anything productive; notice that even the light basketball from two years ago (rebound rumble) hardly launched off the board.

Would attaching the pistons at the very bottom of the board make that much more effective that it can launch a ball across the room? It also seems as though the pistons are extending much too slowly; is there anything we can do to fix this?

Piston setup:



Robot Ramp (in bag):



Walkthrough of testing setup:

https://www.dropbox.com/sh/eob698yuo...kthrough.mp 4

Test 1:
https://www.dropbox.com/sh/eob698yuo...320_175538.mp4
Test 2:
https://www.dropbox.com/sh/eob698yuo...320_175720.mp4
Test 3:
https://www.dropbox.com/sh/eob698yuo...320_175801.mp4
 


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