Ball Damage

[cbolin]

Hi,
After test firing for an hour (about 150 test shots) we stripped off about 10 - 15% of the surface of the ball. The ball is still useable but sure is ugly. Any idea if there are limits to ball damage by a bot? Shooting a ball one time causes no noticeable damage...but 150 it becomes obvious to everyone.

Regards,
ChuckB

[generalbrando]

Generally in the past: Unless your robot rips a couple of new balls to pieces, the Ref usually won't even question it. They expect wear and tear. So if you mess up an old ball, no worries.

They'll replace balls as necessary to make sure they are reasonably consistent, but you have to take some variance into account in your design.

[Unglued]

i noticed that the part where the 2 colours meet seperates very easily, and once there's a rip it only gets worse.

however this dosn't take out any chunks of the balls, the foam stays intact.

by limit i guess you mean when a ball would be taken out of the game?
i think as long as the ball keeps it's original shape it'll be kept in play.. since balls can be scored on either net i doubt some colour wear would get them replaced.

unless they are worn down creamy coloured balls of foam?

anyways i apart from them being ugly i don't think you should worry.

[Taylor]

Ball wear is a definite concern, especially for shooter bots. Any non-sphericalness (yeah, I just called up Noah Webster and had that put in the dictionary) will distort the ball's path. I've seen quite a few pics and movies around with people using belt sanders etc. to move balls - while I realize these are only mockups, similar methods will be used. So be advised - don't design a robot that is based on perfectly round balls.

[Greg Needel]

i think as long as the ball keeps it's original shape it'll be kept in play..



In 2001 the black balls which were inflatable became eggs. First just left them on the field as long at they were inflated. I suspect that balls will remain on the field as long as they can roll.

also just out of curiosity what kind of thrower are you using when you are messing up the balls, might it have something to do with the material the ball touches?

[Billfred]

For reference, I put a question in at FIRST Q&A to see if they've set a criteria to determine when a ball is Too Pooped To Play. We shall see what we're going to have to deal with.

[Nitroxextreme]

Also teams need to consider how much the ball will be broken in...

a new ball when compacted will shoot further than a used ball that isn't as tough and squishes easier

[teh_masterer]

we played with the ball (in dodgeball fashion) around the shop and saw how much the ball was damaged after a few hours. Besides a few gashes and holes in the ball we seemed to make the ball alot less rounder than it was. Good thing we ordered an extra 24 we will have plenty more to use. When does first think the ball has expired?

[Jeff Rodriguez]

An official point of a ball not being useful has not yet been determined.

FIRST will attempt to get the maximum use of all playing objects, while still ensuring the objects are useful to teams.

Teams should not expect that all scoring objects will remain in an "as new" condition for the entire event.
http://forums.usfirst.org/showthread.php?p=473

[Leo 1529]

What if a ball has split in half during a match. Like if it splits in half from being run over or just over use or shot too many times. How would FIRST score the two halves of the ball?

[Andrew Blair]

Well, if they were destroyed during firing, they probably wouldn't roll down to the camera for scoring. If they were run over, they probably wouldn't ever make it into a scoring area. Regardless, we will see a half of a ball score eventually.

[Leo 1529]

Well, if they were destroyed during firing, they probably wouldn't roll down to the camera for scoring. If they were run over, they probably wouldn't ever make it into a scoring area. Regardless, we will see a half of a ball score eventually.


I hope im there to get it on video so i can put it in this years robotics movie.

What about balls that get gashes or holes that might be still be playable. would anyone think that the balls should be allowed to still be used with some chunks taken out or gashes in them?

[Rombus]

im wondering if there going to keep vacuming the field after every 10 or so matches. All the junk comming off these balls might make some interesting field conditions!

[Leo 1529]

im wondering if there going to keep vacuming the field after every 10 or so matches. All the junk comming off these balls might make some interesting field conditions!

thats a good point the floor could get slippery in spots. Every match will differ because of the dust or parts of the ball getting ground into the carpet.

[greencactus3]

thats a good point the floor could get slippery in spots. Every match will differ because of the dust or parts of the ball getting ground into the carpet.
also time to cover up those gears. im gonna hope theres no big enough chunks to jam roller chain tho..

[Ianworld]

I think people are overestimating the damage that will occur to the balls. 150 shots with a ball is a lot. A ball will likely only get fired once a round on average. Most regionals have between 70 and 100 matches so a ball should probably last a whole regional under normal wear and tear. Also this wear and tear isn't going to radically alter the shape or use of a ball like a gash. I think actual gashes will not happen that often. Especially with the constant use of bumpers, most robots are going to definitely just push balls away instead of driving over them(not that driving over them guarantees damage.) There was a huge fear that big robots knocking over the boxes in 2003's game stack attack would just cause massive field destruction but it turned out to be unfounded. The reason being is that robots that cause damage to game pieces just can't use them, so on the first sign of damage people start working on their robot fix it. By the time regionals come most robots will be pretty game piece friendly and those that aren't will quickly become friendly. By nationals there will probably be almost no damage to the field pieces of any major amount.

[AV_guy007]

I hope im there to get it on video so i can put it in this years robotics movie.

What about balls that get gashes or holes that might be still be playable. would anyone think that the balls should be allowed to still be used with some chunks taken out or gashes in them?
that would be cool i have a shot of our robot destroying one of the plastic Tupperware Containers used in stack attack. :ahh:

[BuddyB309]

Now if they would have used cubes we wouldn't have this problem.

[Leo 1529]

I think people are overestimating the damage that will occur to the balls. 150 shots with a ball is a lot. A ball will likely only get fired once a round on average. Most regionals have between 70 and 100 matches so a ball should probably last a whole regional under normal wear and tear. Also this wear and tear isn't going to radically alter the shape or use of a ball like a gash. I think actual gashes will not happen that often. Especially with the constant use of bumpers, most robots are going to definitely just push balls away instead of driving over them(not that driving over them guarantees damage.) There was a huge fear that big robots knocking over the boxes in 2003's game stack attack would just cause massive field destruction but it turned out to be unfounded. The reason being is that robots that cause damage to game pieces just can't use them, so on the first sign of damage people start working on their robot fix it. By the time regionals come most robots will be pretty game piece friendly and those that aren't will quickly become friendly. By nationals there will probably be almost no damage to the field pieces of any major amount.

you may be right the damage to the balls may not be as much as currently noted. we have still been using the ball and it doesnt seem to get as torn up as it was the first time we were using it.

the balls i guess get tougher as they are used as well as change color

[dtengineering]

Our "shooter", like most discussed on this thread, causes damage to the skin of the ball. Not a great amount, but enough that I have been following this thread and the related discussion on the Q&A forum. There have been a few questions asked regarding shooter mechanisms damaging the ball, and the Game Design Committee's replies have been... well... rather severe.

I quote from thread: http://forums.usfirst.org/showthread.php?t=288

"...if your shooting mechanism tears off large chunks of the skin or clearly abrades the skin, it will not be allowed."

Interpreted at it's most draconian, I suspect not many teams are going to be shooting balls.

I think our single-wheeled shooting mechanism is okay... but how is one to know?

Does any team have a shooter that does absolutely NO damage to the ball?

Jason

[artdutra04]

Our "shooter", like most discussed on this thread, causes damage to the skin of the ball. Not a great amount, but enough that I have been following this thread and the related discussion on the Q&A forum. There have been a few questions asked regarding shooter mechanisms damaging the ball, and the Game Design Committee's replies have been... well... rather severe.You probably should try to eliminate as much of this damage as possible in your design. This is for two reasons - the first being the most obvious. You don't want to have to redesign your shooter at your first regional because it did too much damage to Poof balls. Second, if you plan on buying twenty or forty Poof balls to test with, and if you "destroy" a Poof ball after only ten of fifteen shots through your shooter, you aren't going to get much practice in. :ahh:

Using a high-traction ball shooter that takes [even small] chunks out of the Poof balls would make every ball on the field a disaster. In addition to the field itself. I don't think field reset volunteers want to vacuum up the field every other match. A good rule of thumb would try to be able to shoot the same ball fifty, sixty - even a hundred - times before it gets too "used up" to be in a playable condition.

[ChrisCook]

im not sure what you are doing to the balls but check out this shooter from Team 670.

http://math.hhs.fuhsd.org/
- (Under downloads)

[sciencenerd]

Does any team have a shooter that does absolutely NO damage to the ball?

My team hasn't done as much testing as it sounds like many teams here have, but so far we've probably fired some of our poof balls through our shooter as many as 20 times, and none of them seem damaged at all (although we haven't actually inspected them in detail).

We are using a two-wheeled baseball shooter approach, with the two wheels on the same side of the ball. The shooter is operated just like a one-wheel design, but there are two of them, with a short spacer in between. We are using the kitbot 8" Skyway wheels.

[foundbobby]

My team also noticed this problem and changed our launching mechanism. Videos of our new and improved prototype shooter can be found at. We test fired the new launching mechanism heavily and did not notice wear as much on the balls with specially fitted wheels. http://robotics.hhs.fuhsd.org/downloads/Ballshooter.avi and http://robotics.hhs.fuhsd.org/downloads/Ballshooter2.avi --3mb symmetrical connection

[Mark McLeod]

Does any team have a shooter that does absolutely NO damage to the ball?
Our shooter does zero damage to the balls after a few hundred shots, so it is definitely possible. You just need to look for a non-abrasive material. experiment, experiment, experiment.

[Faith]

Our shooter does zero damage to the balls after a few hundred shots, so it is definitely possible. You just need to look for a non-abrasive material. experiment, experiment, experiment.

After 100+ shots (while we still had 1 ball) our ball had a little gash in it and that was it. So our shooter does no damage that I can see because the gash was in the ball when we unwrapped it.

[riboSquirrel]

well... our ball... it kind of sprays the outter shell coatibng of pain over almost everything in about a 2 ft range when we shoot it off.. soooo... lets hope that the balls at competition are not foam ones!!!! :ahh:

[Leo 1529]

well... our ball... it kind of sprays the outter shell coatibng of pain over almost everything in about a 2 ft range when we shoot it off.. soooo... lets hope that the balls at competition are not foam ones!!!! :ahh:

the foam ball you have is the kind that will be used in the competition and it is prolly a good idea to figure out why it sprays outer shell everywhere and try to reduce the damage.

the rule is if it damages the ball too much it will not be allowed

[Jack Jones]

Agree - no real damage here. They leave a little color on the wheel, but that's about it. We've got the shots cranked up to 45MPH. Once we gear it down, we expect even less wear.

[Kilrath]

Ball wear is a definite concern, especially for shooter bots. Any non-sphericalness (yeah, I just called up Noah Webster and had that put in the dictionary) will distort the ball's path. I've seen quite a few pics and movies around with people using belt sanders etc. to move balls - while I realize these are only mockups, similar methods will be used. So be advised - don't design a robot that is based on perfectly round balls.

The balls are not perfectally spherical at the start. They are close but not perfect. We like a couple other teams have found the ball not to be perfect but it doesn't seem to affect how they shoot. So unless you are very anal about the shooter shooting perfectally spherical balls you should be fine. :D

[dtengineering]

Earlier I posted that our shooter was seriously ripping up the balls and was seeking to hear if other teams had developed shooters that did not.

We have since gone back to the drawing board and have replaced the wonderfully grippy 8"x2" (actually closer to 9" dia.) Skyway pneumatic wheel with two 8" skyway kitbot wheels and rebuilt the turret to account for the reduction in diameter.

Our ball velocity is down a bit... but that's not a bad thing seeing as how we were well over 12 m/s before. Tonight we hit the 3 point goal from 20' out about 8 times out of ten (the variation was due to how the ball was fed in, I believe... we'll call it human error) with no noticable ball damage.

A note to teams that are ripping up the ball... the rethink and redesign advice is probably good advice. Ball shooters that do essentially zero damage can be built. Ours is a single wheel design (the two skyway wheels are on the same shaft) and it sounds like there are many other zero-damage designs out there.

Thanks to the other teams that have posted their successful zero-damage ball shooting results... it was sounding for a while like EVERYONE was ripping the ball to shreds like we were.

Jason

[Veselin Kolev]

My team is also using a two wheel design, but the wheels are about 5" apart center to center, and are angled inward. Before we angled them inward, the sharp rubber corners would cut into the ball as it was being shot. Now with angled wheels, we have tandential contact, so it works beautifully. Plus having the wheels out like that reduces the height of the shooter, and gives you a mechanical advantage because you're pushing the ball from closer to its center. With six inch wheels direct driven off the CIM, we're getting exactly 11.6 m/s, and about 32 feet at 45 degrees. And zero damage to the balls.