3.2.3 Center Goal
 

To all those who made the NASA/VCU Regional go so smoothly--considering all of the difficulties associated with hosting a first-week regional-- Thank You.

Now, on to business.

Does this sound familiar?
"SHOOT SCORE...SHOOT SCORE...SHOOT SCORE, oops, ummm...SHOOT SCORE"

Rule 3.2.3 of the Revised Competition Manual states:

The Center Goal is located above each Alliance Station. The center six-foot section of each Alliance Station Wall extends to approximately 10-1/2 feet above the floor. A 30-inch diameter opening is located in the extended portion of the wall, centered at 8 feet, 6 inches above the floor. The opening is outlined by a 4-inch wide border of red or blue acrylic. The opening is backed by a rope mesh and suspended chains to absorb the impact of any scoring objects going through the opening. Scoring objects passing through the opening will be deflected downward by the mesh, and will exit the Center Goal by dropping into a collection tube at the bottom of the goal. There, they can be retrieved by the Human Players.

As you can see, I have highlighted, italicized, and underlined at my discretion. Why? Because I watched many a "scoring object" bounce right back out of the center goal at VCU.

Were any matches swayed one way or another due to "bounce-back"? I can't say; however, I can say that I witnessed, on multiple occassions, two out of five balls shot into the center goal bounce back out, never to be counted among the lucky poof-balls who so willingly gave their lives to the AIM HIGH cause.


Now I have questions for you:

1) Have you witnessed bounce-back at your regional?

2) If so, have you seen any attempts made by FIRST to reduce the pervasiveness of bounce-back?

3) If you have not witnessed bounce-back at your regional, what does the netting situation behind the center goal look like? (i.e. what has changed?)

4) Do you find the occurrence of bounce-back ______________?
A) Acceptable
B) Unacceptable


Have a good day.

-Andrew

Re: 3.2.3 Center Goal
 

1) Yes. It seems to be worse when shooting straight on.

2) No.

3) Nothing has changed.

4) A. This is definitely part of the challenge FIRST has given us. If they saw an issue with bounce-back, they would change the situation. FIRST loves to see us franticly coming up with ideas; it's exciting for me to watch the people in the next pit going "It wasn't like this in the shop!" So, I don't see any problem with bounce-back; it's just part of the game.

Cheers,
JBotAlan

Re: 3.2.3 Center Goal
 

You know, i had a feeling that something like this would happen. like i guessed at VCU they would only use solid neon bright green poof balls to throw off the camras, or something like that, to pose a task for teams AT the regionals on the spot. guess i was right.

Re: 3.2.3 Center Goal
 

From what I could tell from the Wildstang invitational, this is only an issue for teams that put a lot of backspin (or forward-spin) on their balls.

We shoot without much spin at all (more like a rifle bullet :) ) and haven't seen this issue (yet!).

Re: 3.2.3 Center Goal
 

as far as i remember from VCU, ther were counting those balls and points. I mean if the ball goes inside the goald and bounces back, it counted in as 3 points. Thats why me and my team was ok with this situation.

Re: 3.2.3 Center Goal
 

That's quite interesting if they did count them as scored, because I believe somewhere (rules or Q/A) it explicitly says, balls that bounce out do not count.
Was this actually happening?

Re: 3.2.3 Center Goal
 

Not really...FIRST told us about the chains from day one. They were a design constraint that had to be thought about when you made your robot.

It's not like they suddenly sprung the chains out of nowhere in week 1 just to screw with our heads.

Re: 3.2.3 Center Goal
 

Right, the things sprung at us as regionals were:
1) The interrupt bug (OK, while not at regionals, after ship nonetheless :ahh: )
2) The 8.2V bug
:)

Re: 3.2.3 Center Goal
 

I always thought that the balls had to fall down the chute in order for them to count...since that's where the sensor is.

Re: 3.2.3 Center Goal
 

Thats what I thought also. I was watching the Arizona Regional on NASA TV(Before the feed got all screwed up and I couldn't watch anymore, but thats another story) and in one of the matches, the balls got stuck in the center goal during autonomas and they had to knock them down so they would be counted. They have to go through the chute to be counted.

Josh
Team Driver/Designer

Re: 3.2.3 Center Goal
 

I noticed in some videos that there was a person standing behind the teams with a long stick to unjam balls.

Re: 3.2.3 Center Goal
 

IFI did a very good job working around these difficulties. I know it wasn't discovered until Week One, but at UTC they explained the bug in very clear language and provided all teams with a sheet with instructions on how to modify the compiler behavior to avoid the issue. Maybe someone who has one of the sheets could post it on CD so anyone interested could find out about it?

Re: 3.2.3 Center Goal
 

i think bounce back is part of the game. if you read carefully it was actually kinda in the hint the "pasta" could have been the pool noddles or the chains in the goal.

Re: 3.2.3 Center Goal
 

1) Yep, mostly by 1276 cause they got up onto the ramp and shot from there so quite a few bounced out.

2) No

3) Same as always

4) Acceptable. Every team agreed with the rules and they should have no reason to complain about the bounceback. It's a part of the game and if the match is lost due to bounceback situations, then you had better fix it if you care enough.

Re: 3.2.3 Center Goal
 

Very few robots had problems with bounce back at AZ from what I saw. We had one ball bounce it (in autonomous), and that was because it hit very low in the goal and hit lexan only, no chains. For all the matches I saw, any problems with bounce back occurred when teams fired rapidly into the goal (many balls piling up and spilling out, or the chains swaying alot from all the shots and tossing balls back out).

Re: 3.2.3 Center Goal
 

Haha, that's what we refer to as the "ball manipulator". When the balls get jammed, we'd have to poke them with the "ball manipulator" to get them down the chute. I was assigned to this task a couple times at VCU.

Re: 3.2.3 Center Goal
 

It's still on the loose.

Was bounce-back spotted at YOUR regional?

Re: 3.2.3 Center Goal
 

I saw some bounce-out at UCF, but the events were pretty isolated. In one day of Peachtree, I think I saw one bounce-out. But about 99.1293% of the balls that passed through the hole stayed there.

Re: 3.2.3 Center Goal
 

There were several "bounce outs" at the St. Louis Regional. Also, our alliance lost one of the Saturday Rounds due to one of the balls being caught up in the rope netting. The refs then waited until after autonomous to knock it down, causing us to lose autonomous.

Re: 3.2.3 Center Goal
 

yes we saw a lot of bounce out from our team and others at GLR. sometimes we would shoot all ten in auto mode and couple would bounce back. as well there were times we got so many in auto mode with our robot and alliance robot that there was a good 20 second delay while they got all the balls down. some1 before said that it was spinning the ball that caused them to bounce out but we have very little spin and still happens. i guess this is something we have to deal with and see what we can come up with to keep it from happening, though it really didnt effect our game to much. so i guess i find this acceptable.

Re: 3.2.3 Center Goal
 

As far as i know, as long as your ball shooting speed remains under 12fps, then you wont have that problem. Dont quote me on this, though, as this is only an observation of other robots, and relative speeds and such.

So anyway, i would check your shooter speed before you complain that the spaghetti doesnt do its job :)

--oh sorry i think a future comment has nullified this post... i didnt realize that the pushing could have been caused by a swing.

Re: 3.2.3 Center Goal
 

1) YES, we had a high rate of bounce back for relatively long shots.
This affected the outcome of some matches for us.

2) The goal stayed the same as initially designed, we would not expect
it to be changed. If it was changed, one might reduce bounce back
for some trajectories, while increasing it for others.

3) We have witnessed bounce back at every regional we attended.

4) Bounce back is part of the game challenge. The chance of bounce
back depends upon the trajectory. We found that high angle shots from
closer to the goal minimzed bounce back, and this is a good thing
for the best shooting positions for most robots. Once we gathered
enough experience with bounce back we learned to avoid shooting
positions that increased the rate of bounce back unless the game
situation forced shooting from these positions.

Our shooter fires at 45 degrees, with a wheel speed that is set by
the range information obtained from the camera. An RPM limit that
produces 12 m/sec is enforced in the software that controls the wheel
speed. Getting bounce back does not mean that you are shooting to
fast. It has more to do with the specific tractory of the ball as it
enters the goal than the speed.

Re: 3.2.3 Center Goal
 

It's not just the speed or spin. It was my observation that if you shoot in a whole mess of balls really quickly, it tends to get the chains swinging. The swinging motion causes them to push some balls back out. I saw a number of balls bounce out at SVR because of this.

Re: 3.2.3 Center Goal
 

We had a good number of our shots bounce out at SVR.

It would appear that the highest number of shots bounce out when you shoot into the upper right portion of the goal--where the ramp is highest, and the chains do the poorest job of deflecting the balls.

It's part of gameplay, and to be expected though.

Re: 3.2.3 Center Goal
 

I think ball scoring is problematical, and it is part of the game. Since it makes it harder for everyone it is fair, but I don't like the chains for this reason. If you made your canon exactly like FIRST said, Firing a poof ball exactly at 12 mps and hitting the goal smack dead in the center, your ball would tend to bounce back. So the better you aimed, the more you were penalized. This just ain't right. I think FIRST was well aware of this problem, but it was just impossible to modify the goals of all the fields of play once competition began. Then you'd have the situation where different FOPs would play differently, and that would be even less fair.

The automatic scoring, particularly in autonomous mode seems buggy. I.e. How can you score just 10 balls low and get 23 points? Like wise how can you score 23 points if you only aim high in autonomous mode? I know the scoring delays in SVR were because the refs were confirming the counts by hand after each match. Don't know if any match was decided by miscounting, but it can happen, and that's part of the game too.

My last gripe is the 'at the buzzer' rule. In my opinion if the ball is in the air when the light goes out it should count. Seems to me unfair that someone puts 5 balls into the goal in auto mode, but it takes a while for them to score, they should get all 15 points. I think the Cheesey Poofs had this problem. They put a lot of balls into the goal, but often they are under counted because they haven't gone through the slot before the possesion changes. (I don't feel sorry for them however.)

Re: 3.2.3 Center Goal
 

At Detroit, based on the experiences gained at GLR, balls that were caught in the center goal ramp when the light went out were manually counted and included in the final score.

As far as the chains, there were some balls that bounced off them in Detroit and didn't score. Perhaps if the chains were plastic rather than metal they would have less momentum when swinging back and forth, and fewer balls would have been deflected out. However then they would also have less mass to absorb the initial impact, so maybe the first shots would have bounced out.

Either way, the field specs were posted. Teams could have elected to install the proper chains in their practice goals, and learn to deal with them then.

Re: 3.2.3 Center Goal
 

Those balls are counted.

Re: 3.2.3 Center Goal
 

This Q&A seems to answer the question about how the balls are counted. Although I am not sure exactly who is in charge of the "Human Intervention"

At one regional (webcast), I even saw more than a 5sec delay after auton to count all the balls that were scored. Did anyone else see this and remember which regional it was?

Re: 3.2.3 Center Goal
 

At GLR the field crew waited until all the balls that were scored in autonomous were actually counted before bringing back human control. Sometimes this was as long as 5 seconds.

Re: 3.2.3 Center Goal
 

I am pretty sure that the chains were not created as a design constraint. There is nothing you can really do to avoid hitting the chains. At both regionals I attended, NJ and long island, the balls seemed to not bounce out. Occasionally, one or two would during big barrages and close matches, so it meant controversy. I watched VCU and the balls could NOT stay in the hoop. That was a chaining mistake. The chains were either too close together or too loose/tight.

Re: 3.2.3 Center Goal
 

Here is just my input after volunteering at the Waterlo Regional.

From what I have gathered most regionals after the first week knew about the inaccuracy of the automatic scoring system and had volunteers in place with counters counting the number of balls which entered each goal. We also would restart a match if the wrong team went on offence after autonomous mode. I am sure that those who were counting the balls counted all the balls that went in the goal even if they were bounced back by the chains. From what I see there was no match that had the final score swayed by a miscount or bounceback by the automated scoring.

Re: 3.2.3 Center Goal
 

If this is the case, whoever was counting balls potentially altered the results of your regional, as the rules quite clearly state that a ball shot into the center goal doesn't count until it's gone into the clear tube.

Re: 3.2.3 Center Goal
 

"The opening is backed by a rope mesh and suspended chains to absorb the impact of any scoring objects going through the opening. Scoring objects passing through the opening will be deflected downward by the mesh, and will exit the Center Goal by dropping into a collection tube at the bottom of the goal."


I just go back to the original definition of the rule, which sounds pretty durned definitive to me. Those are "will"'s up there, not "should"'s. It sounds to me like the original intent of the game designers was for every ball that entered the goal to remain there until it was counted. It was an original design objective FOR THE PLAYING FIELD. Just like the other underperforming areas of the field (automatic scoring system, for instance), that objective has not yet been met, and I'd expect FIRST to try their best to rectify the problem as the season progresses. Just as we must adhere to the rules applying to the robot design, FIRST must adhere to the rules and constraints they originally placed upon the playing field design, so the game plays as fairly as possible for everyone.

Has any GDC member publicly made a statement on bounceback? While a minimal amount of bounceback seems like an inevitable and acceptable part of the game, the extent to which it has occurred seems a bit alarming. I don't think there's a team out there that would complain if FIRST altered the chain design to minimize the bounce-back effect and bring the action of the chains closer to the definition of the rules.

At one event, we shot 3 balls into the center goal. When our fourth shot went in, ALL FOUR BALLS bounced back out of the opening simultaneously. It wa a rather unbelievable sight, and it changed the outcome of that match for us. That seems a little extreme. We have modified our launch parameters to minimize this in future events, but I hope FIRST can think of something simple, cheap, and creative (a curtain of fabric car wash-like strips?) to increase the damping of the balls once they enter the goal.

Re: 3.2.3 Center Goal
 

Dave has.

I guess what bothers me the most about this and other similar threads is the bashing of the field, FIRST, Hatch Technology and the mostly-volunteer staff at regionals. Sure, the field isn't perfectly reliable, the scoring system sometimes screws up, referees don't always see the same thing as the drivers and sometimes things just don't work quite the way we hoped. Sounds a bit like life to me! Isn't the point of participating in FIRST to learn life skills, particularly as they relate to technology and science?

FWIW, I know one experienced head scorekeeper who believes that this year's scoring system is the best FIRST has put together for several years - and that was in week one! This game raised the bar for FIRST and its suppliers, too. The hardware and software needed to count balls and control game periods is not simple ("trivial" tasks like knowing when ball counts are coming from an active goal and how long to wait for valid balls to come in at the change of periods, or how to count all the balls a robot can barf up at once) and I believe it cannot be bulletproof for any price we are willing to pay. (my two cents)