View Full Version : "Heading" balls?
JasonStern
09-01-2010, 21:30
The following rules apply to robot interaction with the balls:
<G44> BALL CARRYING – ROBOTS may not CARRY BALLS.
<G45> Active BALL control - ROBOTS may not control BALL direction with active MECHANISMS above the BUMPER ZONE.
<G46> BALL Penetration Restriction – The BALL must not extend more than 3 inches inside the FRAME PERIMETER as defined in Rule <R19>.
<R19> ROBOTS must be designed so that in normal operation BALLS cannot extend more than 3 inches inside the FRAME PERIMETER below the level of the BUMPER ZONE.
Do I read this correctly to mean we can "head" balls in the air if we don't possess or carry them? Does this also mean we can control the ball direction if the ball falls within our bumper zone from above as long a) the active control mechanism falls within the bumper zone and b) the ball never falls below the bumper zone?
Thanks!
Jason
DMetalKong
09-01-2010, 21:34
According to G45, the restriction on above-the-bumper active mechanisms, it would seem that a device to 'head' balls by hitting them back up would be against the rules. I believe that the 'bumper zone' it is referring to here is the area between and 10" and 16" off the ground, not the area exclusively above the bumpers, and thus G45 applies to above the whole robot.
Edit: Didn't read the original post too well. If the active mechanism is within/below the bumper zone, heading the ball might work. Back to the rules.
Lil' Lavery
09-01-2010, 21:37
I'm going to agree with DMetalKong's interpretation of <G45> and say you cannot use an active mechanism to interact with the balls above 16" from the ground (top of the bumper zone). However, a passive "head" with a frame of the robot would probably be acceptable, though very hard to do consistently or in a controlled fashion.
BRAVESaj25bd8
09-01-2010, 21:44
I cannot find a definition of "active". If it is simply any moving piece, then we should be able to have a stationary ramp or something on the robot which the ball can roll down so long as the track is stationary. If "active" means any part put there solely for the purpose of directing a ball somewhere, then this strategy is not legal. Thoughts?
zaphodp.jensen
09-01-2010, 21:45
So then could you put an active mechanism in the bumper zone(10 to 16 in.) without violating G45? The mechanism wouldn't be above the bumper zone, so technically. . .
NorviewsVeteran
09-01-2010, 21:56
"When reading these rules, please use technical common sense (engineering thinking) rather than “lawyering” the interpretation and splitting hairs over the precise wording in an attempt to find loopholes."
s_forbes
09-01-2010, 21:57
An actuated mechanism used to "head" the balls would very likely be a violation of G45.
However, I haven't spotted anything yet that would restrict heading with an inactive mechanism. It seems like a plausable way to deflect deposited balls back to your half of the field.
Lil' Lavery
09-01-2010, 21:58
So then could you put an active mechanism in the bumper zone(10 to 16 in.) without violating G45? The mechanism wouldn't be above the bumper zone, so technically. . .
Your bumpers are in the bumper zone and cannot be articulated.
zaphodp.jensen
09-01-2010, 22:00
Also, what would the definition of carrying be? The rules aren't very clear. They state:
CARRYING: POSSESSING a BALL that is not in contact with the FIELD
POSSESSION: Controlling the position and movement of a BALL. A BALL shall be considered in POSSESSION if, as the ROBOT moves or changes orientation (e.g. backs up or spins in place), the BALL remains in approximately the same position relative to the ROBOT.
So, how long would the ball have to be on the robot before it would be carrying?
Theoretically, if a ball falls on you while you are moving, and it stays on top of you, that would be carrying.
In response, the bumpers would close to the bottom of the zone so that the active mechanism could be closer to the top.
DMetalKong
09-01-2010, 22:03
Also, what would the definition of carrying be? The rules aren't very clear. They state:
So, how long would the ball have to be on the robot before it would be carrying?
Theoretically, if a ball falls on you while you are moving, and it stays on top of you, that would be carrying.
Yes, that would be carrying. It makes it very important to have a sloped top to your robot so that balls cannot stay up there.
zaphodp.jensen
09-01-2010, 22:32
But how long could the ball stay on the robot while stationary before it becomes carrying?
But how long could the ball stay on the robot while stationary before it becomes carrying?
I'd guess it's up to the judges. Your best bet is to move your robot so that it is no longer carrying the ball, just in case (ex. if the ball drops on to your robot and is on a ledge, move your robot so the ball moves off) ;).
Lil' Lavery
09-01-2010, 22:39
But how long could the ball stay on the robot while stationary before it becomes carrying?
The moment you're in possession of it.
But you are allowed to be in possession of a ball just as long as the ball is moving relative to where your robot is
Lil' Lavery
09-01-2010, 22:43
But you are allowed to be in possession of a ball just as long as the ball is moving relative to where your robot is
Yes, but if you're in possession of a ball while it's not touching the ground, it's carrying.
CARRYING: POSSESSING a BALL that is not in contact with the FIELD.
POSSESSION: Controlling the position and movement of a BALL. A BALL shall be considered in POSSESSION if, as the ROBOT moves or changes orientation (e.g. backs up or spins in place), the BALL remains in approximately the same position relative to the ROBOT
like i said you are not in possession of the ball becuase even if the ball is not touching the ground the ball can be moving while you are stationary so it is in a different position relative to the robots position(i.e. the ball does not remain in approximately the same position relative to the ROBOT)
zaphodp.jensen
09-01-2010, 22:49
I sense a movement to the Q&A section. . .
Captain Fink
09-01-2010, 22:56
Can you funnel balls that land on your robot?
Kevin Sevcik
09-01-2010, 22:58
If the ball stays on top of your robot while you're moving around, you're almost certainly going to be called for carrying. It probably won't be instantly the first time it happens, but the more often it happens to your robot, the quicker it's going to be called. Especially if it just happens to benefit you every time it happens.
Captain Fink
09-01-2010, 23:02
well lets say you block another robots shot and you have it roll of the front of you robot, there is nothing holding it there and at no point do you "really" have control of the ball, you are just getting it off your robot so you dont get a penalty. why not have it facilitated
well lets say you block another robots shot and you have it roll of the front of you robot, there is nothing holding it there and at no point do you "really" have control of the ball, you are just getting it off your robot so you dont get a penalty. why not have it facilitated
If I were a judge, I wouldn't call it carrying, because it is not done intentionally like a robot purposely purposely lift/carry a soccer ball off the ground.
So in conclusion, regarding to the rules the ONLY way to travel with the ball, is to push the ball with you to wherever you want, with the ball touching the ground... The rules are very similar the rules of a real soccer game; you can't move from point A to point B without letting the ball touching the ground.
Captain Fink
09-01-2010, 23:13
ya exactly, i see it as in soccer when you collect a ball that was in the air by "chesting" it and dropping it to you feet for a shot. i want to make sure this is legal before we start building it into our robot
well lets say you block another robots shot and you have it roll of the front of you robot, there is nothing holding it there and at no point do you "really" have control of the ball, you are just getting it off your robot so you dont get a penalty. why not have it facilitated
Because you're controlling the direction. That's why you can't funnel them.
Let's first define these terms according to the manual:
CARRYING: POSSESSING a BALL that is not in contact with the FIELD.
POSSESSION: Controlling the position and movement of a BALL. A BALL shall be considered in POSSESSION if, as the ROBOT moves or changes orientation (e.g. backs up or spins in place), the BALL remains in approximately the same position relative to the ROBOT.
So, let us say that you have a funnel on the top of your robot. By some chance, a ball lands in it and starts rolling. If you are moving, the refs are almost certain to give a penalty, especially if you do it often. If you are stationary, it's an open question--I'd give it a 50-50 of your getting called, depending on the exact ref crew and how often you do it.
Reason: You are controlling the movement of a ball that is on top of you. That isn't quite enough to get the penalty, in and of itself. However, if you're moving, the ball is moving with you (penalty) and if you're stationary, it depends whether the refs think you're also controlling the position. If you simply had a dome or a slope, you'd probably be OK. (Note: Not an official opinion. Use of this opinion to get out of a penalty will do absolutely nothing. Other uses of this opinion may or may not do anything either.)
On the topic of "heading" a ball, I think that there are probably legal ways to do it. I also think that they will be hard to find and have declared officially legal.
Captain Fink
09-01-2010, 23:25
well the ball is always moving relative to the robot so that one isnt in effect and i dont see the difference between having a pyramid on the bot or having an open channel that the ball rolls down
So if the ball somehow got into the robot, and as the robot moves around, the ball moves around. According to that particular rule, this is not controlling the ball, therefore it is not possessing. So even though the ball is off the ground, but the robot is not controlling it, it won't be called carrying.
The difference is that you're controlling the movement, especially in direction.
Tell you what: Don't commit to a design that has channels on the top just yet. Wait until about Wednesday, when Q&A usually opens up. Then ask them if having a channel on top to direct a ball coming down would count as carrying. If they say yes, then it's time for plan B. If they say no, plan A (having a channel) works just fine.
So if the ball somehow got into the robot, and as the robot moves around, the ball moves around. According to that particular rule, this is not controlling the ball, therefore it is not possessing. So even though the ball is off the ground, but the robot is not controlling it, it won't be called carrying.
So, if a soccer player is bouncing a ball on his head, and moving around with it, he isn't controlling it?
Also note the use of the word "approximately". This gives a range that could easily include the ball staying on the robot as the robot moves around. You could also say that the ball is staying in the same position relative to the robot--on top of it--and still get a penalty.
Captain Fink
09-01-2010, 23:42
well in a soccer game that is legal, and he doesnt really have control of it but i guess it counts as possession because someone always has to have control of the ball in the game.
well with this idea i'm not moving with it like in your metaphore, its just going right down to the players feet after he settles it with his head
well with this idea i'm not moving with it like in your metaphore, its just going right down to the players feet after he settles it with his head
Right. I think this needs clarification from Q&A.
This is what happens when you get a 10 vs 100,000 situation: the 10 need to clear up the chinks that they thought would be clear to the 100,000, because the 10, smart as they are, can never completely think like 100,000 "smart enough to be dangerous" people, and some things just aren't clear on intent.
So, if a soccer player is bouncing a ball on his head, and moving around with it, he isn't controlling it?
Also note the use of the word "approximately". This gives a range that could easily include the ball staying on the robot as the robot moves around. You could also say that the ball is staying in the same position relative to the robot--on top of it--and still get a penalty.
POSSESSION: Controlling the position and movement of a BALL. A BALL shall be considered in POSSESSION if, as the ROBOT moves or changes orientation (e.g. backs up or spins in place), the BALL remains in approximately the same position relative to the ROBOT.
This is same thing I was confused about when I read this rule.
Whoever made this rule had a different interpretation of "controlling" from the general public. What they think is that having the robot moving around, but whatever that is inside of it is not moving at all, is called controlling..
So I assume that if the ball inside of the robot moves around in any direction AS the robot moves around, then it is not called controlling, even though many teams might design the internal system in such way that so they can control it, but the judges won't call it controlling..
So to be called Carry, there are two factors, controlling and no contact with the ground....
If the ball is in the robot(no contact with the ground), however as the robot moves around, the ball moves around as well(not controlling), therefore this scenario would not be called carry. This is how I personally understand that rule
Team 115 saw it as you can essentially let the ball "bounce" of of you but not so that you can immediately control it..
We were thinking of using the same foam they use for the goals in a dome shape to essentially let the ball fall close to the robot so we could get to it relatively easy.
Captain Fink
09-01-2010, 23:50
ya i agree with with you, it is on the verge of being illegal, that's why i brought it up here, so someone could tell me exactly if it was illegal or not, cause i already know most of the rules, but if we could it would be an interesting an effective stratagy
Captain Fink
09-01-2010, 23:54
yeah so why can you have it "bounce" down a channel and put the ball in front of your robot
ya i agree with with you, it is on the verge of being illegal, that's why i brought it up here, so someone could tell me exactly if it was illegal or not, cause i already know most of the rules, but if we could it would be an interesting an effective stratagy
Unfortunately, CD is not an official source for information. We can figure out some things, based on the manual, but other things need clarification. I'm interested in the answer too, for other reasons [insert evil laugh]. That's where the FRC Q&A comes in. They typically open it up about halfway through Week 1, after Update #1 comes out and fixes all the obvious stuff.
dtengineering
10-01-2010, 00:13
Q&A of course is for official clarifications. Note however, posession is defined as controlling the position AND direction of the ball. Not the position OR direction.
The example given in the rules, is essentially that if you move your robot and the ball moves with you, then you are in possession.
So a soccer player, continuously heading the ball, is not likely in posession of the ball given FRC rules. She is not, at any point, controlling the position AND direction... although she may temporarily control the direction.
If you can build a robot that actively heads one of these soccer balls repeatedly, however, I can almost guarantee that not only will you not receive a penalty, but you will also receive a very nice award.... perhaps several.
Likewise, if the top of your robot is sloped to your advantage, or you have an impact absorbent material so that balls don't bouce off you... so long as they don't stick to you... then you're okay.
But if you build an active mechanism... something that you control... that reaches above the bumper zone and affects the ball (whether or not the motor or servo reaches above the bumper zone is irrelevant, it is the mechanism that matters) then you're probably going to have some explaining to do.
Jason
Well from what I read is that you can have a mechanism that reaches above your bumper zone and contacts the balls just so long that when the ball touches the mechanism it is stationary/passive
engunneer
10-01-2010, 11:36
Well from what I read is that you can have a mechanism that reaches above your bumper zone and contacts the balls just so long that when the ball touches the mechanism it is stationary/passive
that is worth a second Q&A topic apart from the 'channel'
I would personally want an angled surface on top that slopes down from back to front instead of a dome. It seems like it should be legal, but i'll wait for the Q/A answer.
What would really help to clarify this rule, is to demonstrate a scenario of carrying and a scenario of not carrying.
EDIT: Don't read here... move along to the next post.... :P
Also, if such a ramp/dome can be deployed and undeployed (say, to allow you to get through the tunnel), does the fact that it can be moved and controlled then make it an active mechanism? Thus, not allowed to interact with the balls above the top bumper plane?
<G45> States that a robot cant control the ball with an active mechanism. If the mechanism deploys upwards and stays stationary when it comes in contact with a ball, considered an active mechanism? or does the mechanism have to be in motion at the time of contact to be considered active?
Thank you,
Team 20
engunneer
10-01-2010, 12:54
Also, if such a ramp/dome can be deployed and undeployed (say, to allow you to get through the tunnel), does the fact that it can be moved and controlled then make it an active mechanism? Thus, not allowed to interact with the balls above the top bumper plane?
That's the same as dodar's question above, I think. It needs to be asked to Q&A once that forum is open. I'm interested in the answer myself.
Also, I think if the answer is no, then how about one that is not actuated, but is simply sprung into the up position but is also flexible?
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