Re: How to get the ball over the overpass!?
 

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.

Re: How to get the ball over the overpass!?
 

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.

Re: How to get the ball over the overpass!?
 

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.

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

Re: How to get the ball over the overpass!?
 

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.

Re: How to get the ball over the overpass!?
 

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.

Re: How to get the ball over the overpass!?
 

If you got this to work, you would probably win every design award your regional offers. lol

Re: How to get the ball over the overpass!?
 

an idea that was thought up by my team was to use a holder underneath the track ball, make the holder go up or down in angle, then have like a pneumatic bulldozer bar shoot out and almost kick it over or shoot if you prefer.

Re: How to get the ball over the overpass!?
 

We're planning on using telekinesis.

Re: How to get the ball over the overpass!?
 

Hmm, can you prove that's a legal power source? As long as you don't use gerbils, I suppose it passes the flowchart.

Re: How to get the ball over the overpass!?
 

Trebuchet? ;)

Re: How to get the ball over the overpass!?
 

1885 is considering using the power of steam, so we're looking into building a great big pot with boiling water beneath a "cannon". It will be complete with a pressurization chamber and several parallel tubes since the durn things are so tiny. We'll also have some 2" Bose speakers on the right side of our robot pointing to the crowd that will play a nice BOOM whenever the ball is shot. Vintage late 1800's :D

No, I'm not serious

Re: How to get the ball over the overpass!?
 

Well you think with over 16 years in the business some form of mutation would show up. That or it's a particularly potent form of geekiness.

Re: How to get the ball over the overpass!?
 

How about dribbling the ball from below. As you drive around you start bouncing the ball straight up in the air. You only have to add a small amound of energy with each bounce thus everything would be quite safe. With each bounce it gets higher and higher and as you pass under the overpass you stop the robot and the ball keeps going. Then you run under the ball and catch it for the next lap. I think a robot that can dribble would definitely earn your team some kind of technical award.

Re: How to get the ball over the overpass!?
 

Sounds like you'd be a perfect alliance partner for us! We'll install our own speakers and play miketwalker yelling out "Oink, oink!" just before you fire!

I can smell the Einstein gold already...

Re: How to get the ball over the overpass!?
 

our team is considering the forklift + electric actuator design.

We would forklift the ball atleast 3' above the ground and use the actuator to hurdel the ball over the overpass... of course balance is crucial in this case, but if we tilt fork lift so it would form a right triangle from the back of the robot of the front, all the weight will be on the center of the bot rather than the front...

what do you think??