Chief Delphi - Catching a ball

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Chief Delphi (http://www.chiefdelphi.com/forums/index.php)

- General Forum (http://www.chiefdelphi.com/forums/forumdisplay.php?f=16)

- - Catching a ball (http://www.chiefdelphi.com/forums/showthread.php?t=124123)

tStano

05-01-2014 21:55

Re: Catching a ball

Quote:

Originally Posted by yash101 (Post 1321914)

If I understand you correctly, if you catch but have no way of ejecting the ball, you will screw the team because there is only one ball available at any time (of your color)

You have some sort of gate at the bottom of your robot that opens up, releasing the ball to the ground near a robot was my original thought on that. Sorry that it wasn't clear.

The issues I see is how easy it would be to get an opponent's ball, and the loss of auton points.

Davis Racing

05-01-2014 22:21

Re: Catching a ball

Being able to catch adds 20 points. These points are added instantly, without waiting for the ball to be scored and could be used as an "end of game" move. Thus, a robot that can catch and release into the 1 point goal over multiple cycles seems to be worth more than a robot that can pick up a ball and shoot at the high goal. Of course, without an alliance partner capable of throwing...
Based on my interpretation of the rules, a catching robot is allowed to have a catching device that expands to cover about 30 square feet.

YCJeon772

05-01-2014 22:41

Re: Catching a ball

Quote:

Originally Posted by who716 (Post 1321951)

have a catcher that doesn't catch the ball every single time wouldnt be any slower though because you would still be chasing a bouncy ball around the field but when you do catch you would safe time catching is important

Well yes, but you would spend that extra 1-5 seconds trying to catch the ball, which can make quite a difference in some cases. And of course you still have to get the bouncing ball, but you could also cycle by rolling the ball under the truss, if it happens to be better than going over the truss.

CalTran

05-01-2014 22:49

Re: Catching a ball

Quote:

Originally Posted by Davis Racing (Post 1321987)

I don't understand where you came up that catch points both add +20 and are added instantly...
Per the game manual,

Quote:

Originally Posted by Game Manual Section 3.1.4 Scoring

Points are awarded once per CYCLE for BALLS SCORED by ROBOTS in the GOALS, BALLS SCORED by ROBOTS over the
TRUSS, and for each ROBOT CATCH. Additional points are credited to an ALLIANCE upon each GOAL based on the
number of ASSISTS earned by the ALLIANCE for that CYCLE.

...

A CYCLE is the series of events that recur regularly, and each CYCLE begins with an ALLIANCE member retrieving their
BALL from their lit PEDESTAL and ends when the BALL is SCORED in a GOAL. Major events in a CYCLE are depicted in
Figure 2-1.

Emphasis mine.

TucoSalamanc

05-01-2014 22:50

Re: Catching a ball

We had an idea of extending aluminum rod backed lexan out 20 inches on each side of us with a slight lip. We are trying to find a way to get it to pull inwards, but have not yet. We think it should count for a catch if the ball lands in this permitter and stays on the platform, we retract it, the ball falls to the ground and we pick it up from there.

One idea for extending was to have an aluminum zig zag thing (like the bottom of an ironing board, repeated, like on a construction lift) that would extend a canvas. This may not count as catching thought, but it could work. :confused:

tStano

05-01-2014 22:52

Re: Catching a ball

Quote:

Originally Posted by CalTran (Post 1322025)

I don't understand where you came up that catch points both add +20 and are added instantly...

catch 10+ truss 10 = 20 points. This thread explains it to the best of our knowledge. It still is rather unclear until the QA answers the question.

http://www.chiefdelphi.com/forums/sh...hreadid=124126

pandamonium

05-01-2014 23:35

Re: Catching a ball

Yesterday I thought catching would happen by gently tapping a ball over the truss. Today watching an interesting game of racket-ball I realized the true potential of catching.

Robot 1 gets ball from human player and immediately shoots it over truss at far wall. Robot 2 is approximately between 2 and 3 feet in front of the wall and catches the rebound. My prototype of a 68 inch box seemed to be able to catch a good deal of balls from 35 feet... Then 1 or 10 point goal shoot as you see fit.

Always keeping your shooting / acquiring mechanism facing the goal is a huge advantage! Also even when the ball is not caught it should be close to you.

asid61

05-01-2014 23:37

Re: Catching a ball

Quote:

Originally Posted by tStano (Post 1321872)

I don't think you catch because of the extra 10 points. I think you catch because then no one has to chase down a bouncing ball that had a decent amount of energy imparted in it. Personally, unless you have enough resources to make an excellent thrower, I think its a really really good idea to concentrate on catching, even if it means you can't throw. You may not do so well in quals but I think you will see the value in elims, as it is a really quick assist.

Just make your robot a huge 5 foot tall target with 20 inch extensions, the whole thing padded to deaden the ball and some way to release it to the ground. If all else fails, you turn around and play the kind of defense where you're a 5 foot tall box that it is unlikely anyone can shoot over. This is just my personal opinion, and my team does not agree, and we will not be building this.

I 100% agree. The bouncing ball problem was one reason that we almost ruled out high-court shooting or shooting over the truss; chasing down that ball could be a big problem. If you use a simple pusher to herd the ball into the low goal, it's not much of a problem. But if there is a high court shooter who needs to chase down the ball, a catcher could be a big part of the game.

yash101

05-01-2014 23:39

Re: Catching a ball

Quote:

Originally Posted by tStano (Post 1321966)

My design actually consists of both, allowing the balls to be picked up, caught and shot! Also, run the conveyor backwards and it will do a pass at a low speed that won't damage the other robot.

Riverdance

06-01-2014 12:50

Re: Catching a ball

Quote:

Originally Posted by erniep (Post 1321821)

So, is anyone catching (or throwing really)?? Just wondering what the thoughts are since we all are playing nice together this year.... Not that we're not nice to each other other years...it's just....well you know what I mean.

"Throwing" (over the truss) can be accomplished using a shooter designed to shoot at the high goal. The truss is about a foot lower than the high goal, so any shooter made for the high goal will also be able to clear the truss.

Catching seems difficult, but what we have figured out recently is that everyone is making catching a lot harder than it has to be. The manual defines catching as "when a BALL SCORED over the TRUSS by a ROBOT’S ALLIANCE partner is POSSESSED by that ROBOT before contacting the carpet or HUMAN PLAYER" and possession as "A.“carrying", B. “herding”, C. “launching, and D. “trapping"". Thus, a catching mechanism is not entirely required unless a team has the time, space, and resources. If a robot simply places itself in the right place such that the ball will bounce off and head in the right direction at the right angle, it should theoretically count as a catch.

That said, my condolences to the poor referees who have to decide what counts as a catch, what counts as possession, and what counts as an assist.

mwtidd

06-01-2014 12:59

Re: Catching a ball

Quote:

Originally Posted by pandamonium (Post 1322079)

Yeah, I've been thinking about this too, and there's nothing preventing the first robot from being a goalie. I wouldn't be surprised to see an alliance turn it into something similar to volleyball at some point.

Human Player throws it up goalie serves it, second robot either takes the shot or serves it up for a third assist.

If an alliance was able to do this, the importance of a goalie would be critical.

Even just a static punter would be quite valuable.

Hallry

06-01-2014 13:00

Re: Catching a ball

Quote:

Originally Posted by Riverdance (Post 1322390)

Catching seems difficult, but what we have figured out recently is that everyone is making catching a lot harder than it has to be. The manual defines catching as "when a BALL SCORED over the TRUSS by a ROBOT’S ALLIANCE partner is POSSESSED by that ROBOT before contacting the carpet or HUMAN PLAYER" and possession as "A.“carrying", B. “herding”, C. “launching, and D. “trapping"". Thus, a catching mechanism is not entirely required unless a team has the time, space, and resources. If a robot simply places itself in the right place such that the ball will bounce off and head in the right direction at the right angle, it should theoretically count as a catch.

Er, check the blue box under that definition:

Quote:

Examples of BALL interaction that are not POSSESSION are

A. “bulldozing” (inadvertently coming in contact with BALLS that happen to be in the path of the ROBOT as it moves about the FIELD) and

B. “deflecting” (being hit by a propelled BALL that bounces or rolls off the ROBOT).

A BALL that becomes unintentionally lodged on a ROBOT will be considered POSSESSED by the ROBOT. It is important to design your ROBOT so that it is impossible to inadvertently or intentionally POSSESS an opponent’s BALL.

(Emphasis mine)

Therefore, a ball bouncing off a robot placed in the right place seems to be just "deflecting," which is NOT possessing and therefore NOT a catch.

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