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Unread 26-03-2014, 22:05
TheHolyHades1 TheHolyHades1 is offline
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TheHolyHades1 is a jewel in the roughTheHolyHades1 is a jewel in the roughTheHolyHades1 is a jewel in the rough
11th Hour Question about pneumatic catapult piston arrangement

Hello,

Tomorrow we are set to attach the pistons to our pneumatic system on the robot. We've tested a configuration where the pistons are almost vertical (pics below), but I've noticed that just about all of the teams have the pistons in a different formation (more pics below). If we were to try to implement the second formation, we're wondering if we would get any significant improvement over our current design? The way the robot is right now, we'd only be able to use about 1/2-3/4 of the stroke with the horizontal arrangement, and that would be at a further distance from the axis of rotation that we have currently. That being said, I'm sure there is a reason teams have chosen the horizontal arrangement instead of the vertical arrangement, and I'm asking why here because we're simply out of time to test a new setup (extensively) before setting it on the robot; however, if we could find a reason here to switch, that would certainly be something we'd do.

Current setup: This isn't *exactly* like the robot, but all of the dimensions are approximately the same, +/- about half an inch. As you can see, the pistons are almost vertical and they're pushing straight up. We've since raised that bottom bar (going into the photo) up a few inches so that the pistons start at their 0 extension position and then only extend to about 1/2 of their extension, at which point the entire mechanism is stopped with some rope/pericord. This barely gets the ball over the 6' mark (truss) (and goes about 3-4' horizontally, so not much room to adjust the angle), so we're hoping that we could improve it to get the fabled 18' across the field shots (more than likely unrealistic 2 days before the district event, but still, no harm in dreaming, right?). This setup also has the effect of ripping the hinges that we're using apart; a lot of the force being applied initially is being sent straight up, and we've noticed (in slow motion video) that the hinges are being bent up and then converting some of the motion to angular motion. We've ordered stronger hinges, but we fear the worst for them in this setup.



Proposed setup: There would be a piece of metal/plywood (spray painted grey) which gets mounted underneath the bar going into the picture on the left, along with a new bar that gets mounted going into the picture on the right, as denoted by a light grey box bounded by dark grey lines. The pistons then get mounted using the same hardware in the new position (denoted by red). Hopefully my amazing mspaint skills communicate this new geometry successfully.