How to get the ball over the overpass!?

[robogeek753]

Still pretty impressive (must of been one heck of a piston and/or ramp) but it makes more sense now.

See you at the Oregon Regional (can't wait to see that giant ramp w/ piston launcher!)

[DonRotolo]

Originally Posted by Hachiban VIII

With pneumatics I'm gonna say thats imposible

Nothing is impossible...but I sure would hate to be the guy who had to make that work...

[BigWhiteYeti]

I think the best way to make use of a piston would be in combination with a forklift, using the lift to raise the ball to five or six feet, then jabbing at it with pneumatics to push it over. I think this would be the most efficient way to hurdle the trackballs. Unfortunately (in my opinion) our team is bent on trying to create an arm with a three-point pneumatic grabber. If anyone manages to create an efficient grabber that won't tip the robot when it tries to hurdle the ball, I'd like to see it.

[robogeek753]

Our idea (suprisingly enough, we haven't had enough time to build it) is to build two concave claws that support the ball (much like the overpass), lift it up to 6'3" and then use two small but long pistons to roll it over or into the overpass (if into then we just move forward a pit and push it out). Due to the small force the pistons are exerting, the robot won't tip.

[silicon_ghoti]

Originally Posted by Hachiban VIII

Perhaps I should qualify my previous statement by saying that the ball was launched off of our ramp and landed 4' away. Such a design could be used to hoist the ball up the desired height and then shoot it over the overpass. But shooting from the ground... Well... With pneumatics I'm gonna say thats imposible

Hmmm... I was thinking the same until Monday afternoon. Now as I throw this out there I get the feeling that I may recieve some flak about not reading the manual, but I would like to ask, "Is this legal?"

What we did was take a 2" bore, 2' (about ish) stroke cylinder and cover up the air port nearest the piston, then we pressurized the other side to 60 psi. The piston extended out about 16" and stopped. We then removed the cover (thumb) from piston side port and the piston shot out with a resounding CLANG!!!! (In otherwords a GREAT deal of force.)

But the reason why our mentors questioned the legality is the little FIRST rule that states that, you cannot compress air in "non-Clippard" containers. I have asked an alum, and have yet to hear back. Now I'm curious as to what the FIRST community has to say.

[robogeek753]

Originally Posted by jimsmith2354

We are trying to find out if we can forklift it onto the overpass then push it off and over.

Have you found out yet? (We're trying to find out the same thing)

[popo308]

Originally Posted by robogeek753

Have you found out yet? (We're trying to find out the same thing)

http://robotics.nasa.gov/events/2008_frcwebcasts.php

If you haven't found it buy now here it is....

enjoy

[robogeek753]

I'm not sure you understand the question (one that is being discussed in another thread I started). The question I have, at least, is whether putting the ball on the overpass, then knocking it off (forward, of course) counts as a hurdle.

[Bohalin]

Originally Posted by robogeek753

I'm not sure you understand the question (one that is being discussed in another thread I started). The question I have, at least, is whether putting the ball on the overpass, then knocking it off (forward, of course) counts as a hurdle.

Im sorry ya I did read the question wrong

[Matt H.]

There are ways to launch the ball with pneumatics. Using only a small cylinder our team was able to obtain 2ft. of VERTICAL travel.

The trick is to fill the cylinder halfway (using a latch to prevent it from opening fully). Then once the latch is removed the cylinder will extend incredibly quickly.

It should be noted that this method is potentially unsafe and would require 2 2" bore 1.5ft stroke cylinders to provide about 8ft of lift, but it is definitely possible.

[robogeek753]

If it is potentially unsafe, I don't think that the robot would pass inspection. In addition, depending on where said latch is, it would probably constitute an illegal modification to the pneumatics circuit and/or components. Without explicit permission from FIRST, I wouldn't reccomend that approach on any robot.

[marypim]

Personally, the forklift seems like the best idea to me

Pneumatics, Springs
Pros: Faster, and they may fit in the minimum size dimensions (no need to unfold)
Cons: You'll need a LOT of energy to launch a 10 pound ball 6 feet in the air. The springs to do this would have to be huge, and I doubt FIRST would allow it. Also, how would you reload the springs for more than one hurdle?


Catapult
Pros: I can't really think of any...
Cons: It would have to be huge to get enough leverage to launch a ball, so it would involve some serious unfolding to get out of the minimum size box. Also, when you do have it unfolded, moving would be problematic.

Forklift
Pros: There aren't very serious cons xD
Cons If it becomes top-heavy, your robot could tip. Pay attention to balance.

[MrForbes]

Originally Posted by marypim

Catapult
Pros: I can't really think of any...
Cons: It would have to be huge to get enough leverage to launch a ball, so it would involve some serious unfolding to get out of the minimum size box. Also, when you do have it unfolded, moving would be problematic.

Oh, you just need to spend more time thinking about it

The catapult itself need not be very large, as long as there is some structure on the robot that will hold the ball in position, such as rails or bars that it can rest on. The catapult only needs to be a couple feet long.

We have been using energy calculations to study the feasibility of various catapult designs, I think they figured it would take about 80 or so Joules to launch the ball over the overpass.

Next design we're working on involves a motor, with a flywheel type gizmo with a connecting rod that actuates the catapult. It would be a relatively low speed device that would not need to make more than one revolution per launch, I think.

Fun stuff....we're discussing a few of these ideas on our N.E.R.D.S. forum too.

[MrForbes]

Originally Posted by robogeek753

If it is potentially unsafe, I don't think that the robot would pass inspection.

It's not as bad as Matt suggests....there is some cushioning as the cylinder reaches full travel (it has to compress some air on the top side of the piston as it reaches full extension, because of how the valves work). And the catapult mechanism could be safely enclosed in the robot, with adequate protection around it.

In addition, depending on where said latch is, it would probably constitute an illegal modification to the pneumatics circuit and/or components. Without explicit permission from FIRST, I wouldn't reccomend that approach on any robot.

No modification of the cylinder is necessary, since the latch is on the lever that the cylinder actuates.

[Swampdude]

Well here's what I wanted to do but couldn't because the gigantic flag holder is in the way, although I'd love to see someone try it. Basically, if you could hold the ball at the end of a pole (about 4' long maybe) behind your bot, as you travel towards the bars (finish line), plant the front end of the pole in the carpet with a grippy foot on it, and you pole vault the ball using the bots inertia.
The bot itself is your best source of stored energy which can be transfered into the ball.