ball cannon???

[martin417]

Originally Posted by Hachiban VIII

I believe the reason why 1771 was able to create so much force was becuase they had an excellent seal on the ball.

F = P x A

So if you can gradually build up pressure over a large area you can create a lot of force.

But without a seal on the floor, it'll be pretty darn near impossible to build up pressure.

With a gap, F still = P x A, it is just much harder to get P very big. last year we were able to achieve a delta P of ~1 PSI, so with a 24" seal diameter, we had ~450 lb.s of force. With a 1/8" gap around a similar sized circle, you have a leak area of around 10 in^2 if you look at this as on orifice, it would equate to a diameter of ~3 1/2". if you can move enough air to get a pressure drop of 1/2 PSI, you have effectively added 225 lb.s to your bot. (not to mention the added benefit of the Bernoulli effect at the rim, very cool!)

You also now have 225 lbs of force trying to lift a .90" thick fiber panel from the floor. (have you ever seen an animation of "storm surge" in the eye of a hurricane?) I cannot imagine the rules committee allowing this.

[2241]

Originally Posted by Petey

My $.02? You will see almost no successful launchers this year. A few teams will pull it off, and we will marvel at them and slap our forheads and say OF COURSE, but most of the most successful teams will find a way to get balls reliably and quickly to the human players (including all four empty cells) and then have a human player who is absolutely golden scoring goals.

Someone namedropped Aim High; I'm thinking more like 2004 here.

i agree with this guy. there will be no successful launchers, however that doesn't mean there will not be launcher like items used, however i don't agree that the human players will have to be the reliable scorers. it will come down to dumping, if you can get a cage to dump with enough force, it will create a shotgun effect, and will score more effectively than anything else.

[AlexD744]

I think with the openings in the balls there would be very little accuracy from a shooter especialy from a moving target. There air passing through the ball would veer it in a different direction every time.

[JesseK]

Originally Posted by AlexD744

I think with the openings in the balls there would be very little accuracy from a shooter especialy from a moving target. There air passing through the ball would veer it in a different direction every time.

We prototyped a shooter yesterday, and were able to get it to go 6 feet consistently within a 20-degree or so spread. Now all we have to do is adjust the speed, angle, and have a decent feeding mechanism. We should have an accurate shooter out to 10 feet or so...but 10-15 foot shots are our strategy anyways. It's possible, even with how squishy the balls are -- I'll post a picture sometime next week.

Originally Posted by 2241

i agree with this guy. there will be no successful launchers, however that doesn't mean there will not be launcher like items used, however i don't agree that the human players will have to be the reliable scorers. it will come down to dumping, if you can get a cage to dump with enough force, it will create a shotgun effect, and will score more effectively than anything else.

This is a VERY bold claim, especially for someone from such a high team number. I expect we'll see some teams with frighteningly accurate shooting mechanisms. After all, this is FIRST... and we've seen some pretty amazing systems in the past, many that no one thought could be done.

[Jon Stratis]

Originally Posted by 2241

i agree with this guy. there will be no successful launchers, however that doesn't mean there will not be launcher like items used, however i don't agree that the human players will have to be the reliable scorers. it will come down to dumping, if you can get a cage to dump with enough force, it will create a shotgun effect, and will score more effectively than anything else.

the concept of shooting here is pretty similar to other situations where industrial solutions have been created. This of a battle ship on rough seas - the gun turrets mounted on the deck are able to compensate for the swells, keeping a constant trajectory lock on their target, even when the ship rolls 30 degrees from one side to the other. Likewise, the targeting system on a jet doesn't just tell you to squeeze your guns when you're pointed right at the guy - it compensates to lead the enemy plane with an intercept vector. A bomber doesn't drop when it's immediately over the target - it plots an intercept vector for the bomb.

If you look closely, you can find tons of examples where similar targeting/shooting/launching systems have been created and work - it's not unreasonable to expect that some teams will be able to achieve this as well. Especially since this technology has been available in military systems for decades.

[eschanz]

but you'll be moving around and the lag between the camera and shooting will through off the entire thing

[XXShadowXX]

Originally Posted by eagle33199

the concept of shooting here is pretty similar to other situations where industrial solutions have been created. This of a battle ship on rough seas - the gun turrets mounted on the deck are able to compensate for the swells, keeping a constant trajectory lock on their target, even when the ship rolls 30 degrees from one side to the other. Likewise, the targeting system on a jet doesn't just tell you to squeeze your guns when you're pointed right at the guy - it compensates to lead the enemy plane with an intercept vector. A bomber doesn't drop when it's immediately over the target - it plots an intercept vector for the bomb.

If you look closely, you can find tons of examples where similar targeting/shooting/launching systems have been created and work - it's not unreasonable to expect that some teams will be able to achieve this as well. Especially since this technology has been available in military systems for decades.

This a great point. I would like to remind people that military could hit targets 23 miles away with there battleships in the 1940's using vacuum tubes, and punch cards we have 400Mhz processor, and a color camera...

Originally Posted by eschanz

but you'll be moving around and the lag between the camera and shooting will through off the entire thing

So make your math to account for it.

[jgraber]

Originally Posted by martin417

With a gap, F still = P x A, it is just much harder to get P very big. last year we were able to achieve a delta P of ~1 PSI, so with a 24" seal diameter, we had ~450 lb.s of force. With a 1/8" gap around a similar sized circle, you have a leak area of around 10 in^2 if you look at this as on orifice, it would equate to a diameter of ~3 1/2". if you can move enough air to get a pressure drop of 1/2 PSI, you have effectively added 225 lb.s to your bot. (not to mention the added benefit of the Bernoulli effect at the rim, very cool!)

You also now have 225 lbs of force trying to lift a .90" thick fiber panel from the floor. (have you ever seen an animation of "storm surge" in the eye of a hurricane?) I cannot imagine the rules committee allowing this.

Thanks for the calculation examples.
On a "storm surge", the ocean surface is fluid. The Regolith is a solid.
If there were an airsource under the regolith, it might be a problem.
If the a cardboard box lists 40psi bursting strength, I don't think Regolith will have a problem. I'm looking forward to this being asked in the Q&A though.
I'm pleased to see that nearly every cool idea of mine has already been discussed in detail here already.

[martin417]

Originally Posted by jgraber

Thanks for the calculation examples.
On a "storm surge", the ocean surface is fluid. The Regolith is a solid.
If there were an airsource under the regolith, it might be a problem.
If the a cardboard box lists 40psi bursting strength, I don't think Regolith will have a problem. I'm looking forward to this being asked in the Q&A though.
I'm pleased to see that nearly every cool idea of mine has already been discussed in detail here already.

Regolith can NOT be treated as a solid. For purposes of discussion, think of it as a thick sheet of paper. A .090" Thick piece of fiber board is very flexible, and can deform a great deal (not as much as water obviously) It will be sitting on carpet, which is a porous medium, full of air at 14.7 PSI (in ideal terms at sea level, STP blah, blah, blah). If you expose the top side of this flexible member to a reduced pressure, say 14.2 (1/2PSI delta) you will have that 225 pounds of force pushing up on the sheet. One of the kids almost broke a window at the school last year by sticking the funnel against it with the vacuum on. If a quick thinking person hadn't turned off the vacuum immediately, the glass would likely have shattered. As it was, a witness on the other side of the glass said that it bowed inward a significant distance before the vacuum was shut off.

No cardboard box can withstand 40 PSI internal (or external) pressure (unless it is very tiny). Perhaps 40 PSI is the breaking strength of the cardboard? At my last job we had a cube shaped hydraulic tank pressurized to 5 (five) PSI. It was large, maybe 28" on a side. In order to prevent bowing of the sides, it was 3/8" thick steel with internal ribbing.

[The Pre]

if any of you were at the wisconsin regional in 2006 or saw team 111 (wildstang) play at nationals you know what a ball cannon can do...

or if any of you saw the team that won the chairmans award in 2006, team 111 wildstang... this was their ball cannon

i wouldn't be suppirsed if their 20 motorola engineer mentors and the students cranked out some ball launcher with teeth to go into the orbit balls and throw them... or even an arm to throw it.

in 2006 wildstang during the autonomous mode locked onto the target would dump their entire 5-10ball hopper strait into the top target. and when i say strait i mean a solid stream of 10 balls or so dumped in 5 maybe 6 seconds so i wouldn't doubt if there were some more attempts at copying this robot this year

[jgraber]

Originally Posted by Uberbots

This game was practically designed to be a shooter game. ...
The basic logic i have hammered out is you would have a camera mounted on a pan/tilt on top of your turret. ... The camera is on the constant hunt for beacons that your team wants to shoot at. when it locates a beacon, there is a control loop that tells the camera to lock its pan/tilt such that the beacon is in the center(ish) of the feild of view.

Or use a much simpler (lower res) non-linear vision system.
Point the camera straight up at a cone or spherical reflector to get 360 degree vision.

[The Pre]

i think the 360 vision would be pritty crazy!!! props if you can get that to work, i've never used the camera before but that seems really confusing cause there are so many images that can be seen in 360 degrees, how will it know which one to go after?

[MrForbes]

Originally Posted by XXShadowXX

This a great point. I would like to remind people that military could hit targets 23 miles away with there battleships in the 1940's using vacuum tubes, and punch cards

uhhh....I think that was done with mechanical computers and look up tables, since punch cards were used mostly for inventory control and the first vacuum tube computer was way way too top secret to let it go out in the field.

[kaszeta]

After evaluating the ball, I'm pretty sure the pinch-roller mechanism that our team has used before is still viable, but there's definitely a lot less accuracy than in Aim High. I'll probably help the students prototype something if I can get over to their workshop this week.