Balls bouncing out of goal

[Bob Steele]

In viewing the proceedings at VCU I noticed that quite a large number of balls would hit the chains and bounce OUT of the high goal..... Obviously these balls should have counted but could not be seen by the automatic scoring mechanism.. I do not feel that FIRST designed the chains to be an obstacle but rather something that would allow the balls to drop easily.
It is apparent that the inertia of the chains (mass) is too great for the poof balls to move easily.

Can anyone shed any light on this problem?
Any possible solutions? How was this handled at your regional?

thanks

[Jon K.]

FIRST has said that while the chains are up to prevent bounce out it is still a design obstacle needing to be overcome.

[Specialized]

Myself and other members of my team attended the BAE GSR in NH this past weekend. I also noticed this. Unfortunately, those balls were not counted either.

It is unfortunate for the teams who can shoot 10 or more balls effectively into the goal but some of the balls are not counted because they do not fall down and get counted by the automatic ball counter.

Teams like 1276 and 296 were some notable teams that I can remember distinctly not having all of the balls which crossed the plane of the top goal and did not have all of the balls scored.

[Don Wright]

I noticed this as well.

I would think that FIRST would want to examine this and maybe modify the chain/netting to try and make it so that balls that are correctly scored through the opening would stay in better.

But, maybe they did and this is the best they can do. But, I was disappointed when I saw some robots do a great job battling into position with a bunch of balls, only to have them all shoot and score, but the last 3-5 bounce out...

[DjAlamose]

I also noticed this but it has to do with the way the balls are shot. If the balls are shot too fast the chains gain more inertia and force the balls back out of the goal. If the ball has too much spin in any certain direction it will skip on the chins and wither fly up into the goal or down. If the ball flies up it then falls down out of the goal because of the slanted face of the goal. If the ball flies down it has a greater retention rate but it may still bounce off the platform in the goal and come out. A soft shot into the goal with little spin would be ideal, but then the problem then becomes getting the ball to the goal. These where just my observations from the regional mixed with some physics knowledge. With the amount of shooters that were blatantly shooting over the muzzle velocity, i could see why may shots where falling out.

[Kevin Sevcik]

What I saw watching the VCU webcast was balls getting impeded by the chains hanging down in the goals. I saw a ball take atleast 10 seconds to roll past the chains at the bottom of the goal. If this happens during the autonomous mode or before that team goes on defense or the match ends, there's no way that ball is going to score. I realize there's a large technical challenge involved here, but having the scoring system so physically seperated from the goal in this game format means that teams are getting denied 3-pointers simply because the goal is slowing down the balls. However, since the only solutions involve changing the chains or covering the goal instead of turning off the counter, this isn't going to change this year. So I'll be planning on last second shots not counting for anything.

[Tim Delles]

I would just like to highlight rule G05, since it was a design constraint on all teams.

Originally Posted by 2006 FRC Manual - Section 4 - The Game

<G05> In order for a ball to score, it must enter the goal and exit via the exit chute. A ball that bounces out of the goal is not scored. Once a ball is scored for a particular ALLIANCE, it cannot score again until it is entered onto the field by the opposing ALLIANCE’s HUMAN PLAYER.

So this is something that should not really be that big of a thing. We all knew that balls would bounce out.

[Don Wright]

Originally Posted by Tim Delles

I would just like to highlight rule G05, since it was a design constraint on all teams.

So this is something that should not really be that big of a thing. We all knew that balls would bounce out.

I agree... I guess I just didn't think they would bounce out as much as they do.

We will correct. Maybe "upper shelf" our shots into the upper corner of the center goal...

[henryBsick]

The worst is when a ball bouncing out blocks a ball on the way in...
Happened once or twice to 222.

[kawelch]

I assume a ball bouncing out of the goal is akin to rimming out of a basketball goal or hitting of the uprights in a football kick. Just part of the game.

[BoyWithCape195]

Actually, any balls that are on the bottom plane when the buzzer goes off will trigger the system to wait and count them even if the period is over.

[DjAlamose]

Originally Posted by Kevin Sevcik

What I saw watching the VCU webcast was balls getting impeded by the chains hanging down in the goals. I saw a ball take atleast 10 seconds to roll past the chains at the bottom of the goal. If this happens during the autonomous mode or before that team goes on defense or the match ends, there's no way that ball is going to score. I realize there's a large technical challenge involved here, but having the scoring system so physically seperated from the goal in this game format means that teams are getting denied 3-pointers simply because the goal is slowing down the balls. However, since the only solutions involve changing the chains or covering the goal instead of turning off the counter, this isn't going to change this year. So I'll be planning on last second shots not counting for anything.

BoyWithCape is right, but also they had field personnel with long sticks moving the balls to the chute to get them there faster and to free them if they became stuck. I didn’t see any problem with them getting counted, it was just a matter of them staying in the goal.

[Greg Needel]

Originally Posted by Kevin Sevcik

What I saw watching the VCU webcast was balls getting impeded by the chains hanging down in the goals. I saw a ball take atleast 10 seconds to roll past the chains at the bottom of the goal. If this happens during the autonomous mode or before that team goes on defense or the match ends, there's no way that ball is going to score. I realize there's a large technical challenge involved here, but having the scoring system so physically seperated from the goal in this game format means that teams are getting denied 3-pointers simply because the goal is slowing down the balls. However, since the only solutions involve changing the chains or covering the goal instead of turning off the counter, this isn't going to change this year. So I'll be planning on last second shots not counting for anything.

The make up of the goal sensor array is as follows. There are 6 sensors in the center goal (made in arrays of 2) . one array at the far left of the goal, this one shoots a beam down the slant of the goal and is the senor that keeps the goal "active" during auto and the offence periods at the end if there are still balls in the goal. The next array is in the goal right above the hole, this senor is dual purpose dependent on what period you are in but it's main function is to be the first counter of balls. The last array is directly below the second one but is out of the goal looking at the shoot, this is the final counter for balls.

on each player station side there is a desktop computer which is responsible for interpreting the counting senors (both cameras, and the center goal arrays). That computer communicates with the scoring table computer which projects the scores.

Basically don't worry about balls in the goals not counting.

[Rick TYler]

The worst balls for falling out of the chains appear to be those with lots of backspin, which unfortunately described most of those at PNW, especially those shooting with a lot of arc. The spinning motion of the ball is slowed by contact with the chain, and converted to downward motion, pushing it down towards the floor. It's why you want backspin on a basketball -- if it hits the backboard, it tends to go down into the hoop.

I wish we had thought of this before designing a shooter with a ton of backspin...

[petek]

Greg's close, but really there are two types of sensors in the center goal:
Two parallel through-beam sensors which look for balls on the ramp and also validate balls which enter the goal within 2 sec. after the end of a goal-active period. Two are needed to provide coverage of the whole ramp width.

The balls are counted by the through-beam just below the hole in the ramp where the ball drops into the hose.

These through beams are connected to a data acquisition box which talks to the ball counting computer (the PC under the drivers station). The corner goal cameras also connect to this PC. A LabView app. does the all the heavy lifting to figure out whether the signals are valid ball counts and sends the results to the scoring computer.

And we thought making the robots' autonomous work was complex!