Re: Balls bouncing out of goal
 

Ultimately, its just another design challenge...

But, the way out that I see is to shoot closer, slower, and higher. This alone seems to fix much of the problem. But again, another challenge...:rolleyes:

Re: Balls bouncing out of goal
 

I don't see any mention of the balls being deflected back out after they have entered the center goal.
I didn't hear any mention of this possibility at the kick off event. Did I miss a memo? If it had been mentioned we could have allowed for it with our shooter.
I was under the impression that the balls would remain in the center goal after they have entered it.
Is it because the chains are too long and hang down into the bottom of the opening?
Would it help if the chains were behind the mesh? This way they would still slow down the momentum of the balls.

Re: Balls bouncing out of goal
 

I have a few questions for you:

1.) Did your team build a center goal? If so why didn't you test things on it? Did you notice that it was also tilted down (10 degrees from vertical)?
2.) Did you think about spin on the ball when it hits a surface? If so did you account for it being chains, and chains giving back on the ball?

Re: Balls bouncing out of goal
 

I feel that FIRST could have done a much better job with this, (yes its a design challenge and all..). But I feel that the chains should be replaced with a mesh type material, I saw a practice scrimmage which used this and worked beautifully. I haven't seen the game in person yet, But from all the video shots and web casts that I have watched there are a good percentage of the balls bouncing out. It is already tough enough to score in the center with all the defense being played, and having 30+% of your balls bounce out just makes it that much unnecessarily harder. I hope FIRST deals with this problem before there are too many people complaining.

Re: Balls bouncing out of goal
 

Alternately, perhaps a whole bunch of people might hold off on complaining until they actually go back, read the rules, re-examine the field drawings, build a goal, build a robot, practice the shots, and understand that this has been a part of the whole challenge since the very day that the game was announced. Nothing has changed, nothing is different. Perhaps those that are just chomping at the bit to complain might realize that a whole lot of teams figured out that controlling backspin, controlling the azimuth angle of the shot, and controlling the elevation of the shot are all factors in minimizing the probability of the ball bouncing back out, and they were able to do something about it. This is not an issue that FIRST has created, it is something that a few teams failed to recognize as part of the problem. So perhaps those that are so eager to complain might realize that if they spent a little less time complaining and a little more time analyzing the problem and developing solutions, then they might have a little less to complain about.

-dave

Re: Balls bouncing out of goal
 

In our entire day of playing, we only had three or four shots bounce out. I'd propose that those of you who are having 50% bounce out should shoot a bit slower or tone down the spin a bit... we're right at the 12m/s line and have a great deal of spin on the balls. If that's what's causing it, you might be a bit too far on either one of those two things. Then again, maybe it's something else...

Re: Balls bouncing out of goal
 

In the first weeks I was convinced that back spin would be best. After our shooter proto type was finished, the students spent hours testing it and came to the conclusion that top spin was best. The magic angle works with top spin but, not with back spin. And the balls seem to stay in with top spin. It's that poofy ball dynamics thing. They just will not behave the way you want them to.

Re: Balls bouncing out of goal
 

If you are playing foozball and your ball bounces back out of the goal, do you expect the table's manufacturer to fix it? No - you groan and keep playing! Nothing's different here. Like Dave said, it's part of the challenge of playing the game.

Re: Balls bouncing out of goal
 

More and more I'm becoming a big Dave fan :) CD won't let me give him any more rep points though, lol. Back on topic, Dave is absolutely right. Getting upset because you didn't fully understand the challenge of making 3-pt goals isn't going to help your team solve the problem. Our little tiny team quickly realized that there were many variables inherent in scoring high that we probably would not be able to overcome. Shooting the balls in the right direction is the LEAST difficult part of the problem. The downward angled goal looks enticingly easy to score in. As it turns out, it makes it a little easier for the balls to come back out. We opted to concentrate on shooting low, the logic being that we could make 4 1 pointers faster than 1 3 pointer. I have a lot of admiration for the teams shooting high. Just keep working the problem. Those chains are probably staying there so figure out how to make the balls stay in and quit wasting time shaking your fist at them. Reduce shooter speed, change ball spin (really at 12m/s spin doesn't have much effect on trajectory, but with high friction poof balls, spin seems to have a large effect on surface interaction), anyone thought of side spin?, change trajectory, do something to score more reliably! But please wait until after your match against our alliance to fix it! :D

Re: Balls bouncing out of goal
 

Let's look at it as a goal. The chains are the goalie. This goalie is not very good but sometimes you shoot at him/her and the ball is returned to the field. That's the way it goes when playing games. As has been stated earlier, FIRST did tell us about the chains and told us about the scoring procedure.

This may not be the correct place, BUT, my feeling is that FIRST did a great job on this years game, rules and consistency and they should be applauded for it.

Re: Balls bouncing out of goal
 

When we were setting the field up in NJ and tested the goals we found that if you put the right spin on the ball and hit the chain just right, the ball would ride the chain down, catch in the loop at the bottom and hook right out of the goal. Pretty neat. Not easy to repeat, though.

Re: Balls bouncing out of goal
 

Not so hard at all. About a third of our clean hits did (more or less) that. It sure changes the calculus away from backspin shooters.

Re: Balls bouncing out of goal
 

Guess I should've figured: repeatability is one of the hallmarks of good automation.

Re: Balls bouncing out of goal
 

David -
a point of clarification is in order.
The center goal chain drawing was added as New 1-31-06 to the FIRST website for low cost field

I do not recall seeing chains on the field pieces at the kickoff at Kettering University on the very day the game was announced, it was a low cost field element - but then again as every year I am overwhelmed on that Saturday with all that is going on.

Just for clarity sake - we do build alot of the field elements and frankly we totally missed the chains - but, thats our fault and we will figure out how to deal with it by adjusting the way we shoot the balls so that we limit how many bounce out.

I was concerned in another similar thread to this one that the chains could be installed such that they were closer to the opening than designed - as the chain frame is not symetrical according to the drawing for the low cost field. Where as, the official field drawings for the chain installation added 2/9 this year, make it appear to be symmetrical - so I don't know what to think - is the Low cost field drawing for the chain frame correct? I'd like to hang the chains and want them in the same place as the official field elements.

Re: Balls bouncing out of goal
 

the chains were on the Manchester Kickoff field and were visible during the webcast, if i remember correctly.