Defence on the High Goal?

['lil robo-girl]

The high goal is one of the most obvious ways to get more points. Assists, the truss, and other strategy aside, it would make sense to try to prevent the other team from reaching it. However, as you know, we are only given a 6-inch cylinder to work within.
I was wondering if any teams were actively pursuing that mechanism. We haven't totally ruled one out, if we can find an effective enough design, but that does seem unlikely.
So, what basic ideas have you come up with to block the high goal, if you've considered it at all? Even if your team has decided against that particular idea, maybe we could make it work.
Thanks!

[Whippet]

We've come to the conclusion that anything extendable that can reach that high within the rules will either be too brittle and break when hit with a ball, or too flexible and bend, violating the cylinder rule and getting a substantial penalty.

[blaze8902]

Can someone quote the rule that will clarify whether or not you will receive a penalty if your extension bends temporarily due to impact with the ball?

[EricH]

Can someone quote the rule that will clarify whether or not you will receive a penalty if your extension bends temporarily due to impact with the ball?

It's a Q&A, actually. Q116 (https://frc-qa.usfirst.org/Question/116/in-g23-it-talks-about-breaking-the-6-cylinder-as-a-penalty-if-we-have-an-arm-that-deflects-when-struck-by-a-ball-but-then-returns-after-contact-it-that-a-penalty).

[Gearheads1]

We're trying one and feel pretty good about it. Pneumatics and a 2X10; we'll see how it works!

[EricH]

We're trying one and feel pretty good about it. Pneumatics and a 2X10; we'll see how it works!

A 2x10? Isn't that going to be outside the 6" cylinder?

[Gearheads1]

Not if you rip it to closer to 2X6, which is what I really meant. Sorry, long day!

[JohnSchneider]

We've come to the conclusion that anything extendable that can reach that high within the rules will either be too brittle and break when hit with a ball, or too flexible and bend, violating the cylinder rule and getting a substantial penalty.

Unless it is taller than the top of the goal, so that when impacted, both ends of the "pole" are supported by the goal.

[MooreteP]

Unless it is taller than the top of the goal, so that when impacted, both ends of the "pole" are supported by the goal.

But wouldn't that be interacting with the field elements?
Sounds like a Q&A to me.

[staplemonx]

We are using one of these. http://www.sportstop.com/2010-NCAA-HEAD-SPECIFICATIONS

[m1506m]

We are using one of these. http://www.sportstop.com/2010-NCAA-HEAD-SPECIFICATIONS

At 6.5" this would not be within the 6" cylinder.

[Jimmy Nichols]

A concept we were pursuing before we decided to abandon the pole was actuated it outside of out machine so that it was then supported against the back wall to help prevent it from bending.

[Canon reeves]

Our team was going to defend the high goal, but we decided it would be easier for a shooter to move slightly and shoot rather than you move 12 feet, you could be fast enough to do it but if you are to top heavy it's just a fall over waiting to happen. it also can be easily counter defended because all it takes is one robot to come and get infont of you. A team that was able to play midfield and be flexible could be much more effective than a highgoal defender in our opinion.

[apm4242]

Canon reeves - exactly what we ended on, too. Originally we were thinking a double scissor lift mechanism but even with the best <6" diameter arm in the world, counter-defense could be achieved simply by placing another robot in the goalie zone. So, in the end, a strategy that could be completely nullified with something as simple as a large rock was deemed a poor use of time.

On the other hand, if you could vision-detect one of the balls or use another method to consistently block in autonomous, I think this could be very effective.

[JamesCH95]

Re OP: playing goalie was something we nixed early on as ineffective considering our overall strategy.

Considering the height of the 'goalie stick' you'll want to make it as light as possible. The Lacross head posted earlier is a good idea. A hockey stick shaft would work well too. Pultruded fiberglass or carbon fiber poles of sufficient size would also be good. Stiffness is important, so I would lean towards carbon fiber. Worst-case a quality broom handle would probably do the trick, we tested them as deflectors for another mechanism (cantilevered 2-3ft out being hit directly by a ball tossed 20+ft in the air).

Your real issue is deployment and maintaining a stiff mounting point. For the latter I suggest roller element bearings (cam followers are good) with adjustments to take any compliance out of the mechanism and a well-triangulated structure mounted to the chassis of your robot to mount any guides to. For the former I suggest looking at various telescoping mechanisms from various teams over the years, there are many. Also bear in mind that air cylinders can easily be purchased with 2-3ft of stroke, making a directly-actuated mechanism possible.

We've come to the conclusion that anything extendable that can reach that high within the rules will either be too brittle and break when hit with a ball, or too flexible and bend, violating the cylinder rule and getting a substantial penalty.

I believe that conclusion is erroneous.

A 2inx2inx0.125in square aluminum tubing would be wild overkill and won't bend or break. You could easily find a few dozen other OTS material solutions that would also suffice.

[JB987]

At 6.5" this would not be within the 6" cylinder.

The one in the middle is only 6"...

[Steven Donow]

The one in the middle is only 6"...

I believe(if I'm not mistaken from my 5 years of youth lax) that's the opening, which means the plastic would make it longer than 6 in.

Overally, FIRST really stunted defensive efforts compared to last year. I'm okay with that. Because this year effective defense requires much more strategy/driving/less "sit in front of FCS, block) than last year.

[JB987]

I believe(if I'm not mistaken from my 5 years of youth lax) that's the opening, which means the plastic would make it longer than 6 in.

Overally, FIRST really stunted defensive efforts compared to last year. I'm okay with that. Because this year effective defense requires much more strategy/driving/less "sit in front of FCS, block) than last year.

Right you are. Should have had my glasses on:D

[ehfeinberg]

449 had the idea of a high blocker which was a 6 inch wide wall which would spin around one edge really fast, effecively make a 12 inch cylinder of blocking area. This entire assembly would then be placed on another rotating platform extending the range of the blocker. While it would only be 6 inches wide, it would be able to cover a much larger area.

[Shu]

449 had the idea of a high blocker which was a 6 inch wide wall which would spin around one edge really fast, effecively make a 12 inch cylinder of blocking area. This entire assembly would then be placed on another rotating platform extending the range of the blocker. While it would only be 6 inches wide, it would be able to cover a much larger area.

I don't believe that would legal if it could not be fully contained in a 6" cylinder while rotating. Also, if it would impart any force on the ball during contact, that would be another foul.

[waialua359]

Given the restrictive parameters for teams to create devices to block the high goal, I still find it will be very effective to prevent teams from scoring.
Add the fact that there are no Safe Zones, I think many teams are underestimating the defense.

[Tungrus]

If you are planning flimsy blocker be warned, the ball has is 2+ lbs going at some decent speed, it can cause serious damage.

[Madison]

I don't believe that would legal if it could not be fully contained in a 6" cylinder while rotating. Also, if it would impart any force on the ball during contact, that would be another foul.

It's legal. The rule makes no requirement that the virtual cylinder remain fixed relative to the robot. An infinitely thin post with an infinitely thin 6" long stick rotating about a pivot on it satisfies all of the rules. The virtual cylinder will simply oscillate back and forth, with the vertical pole moving from one edge to the other and back.

[Taylor]

Add the fact that there are no Safe Zones,
Well, there sort of are four of them.

[aldaeron]

A 2inx2inx0.125in square aluminum tubing would be wild overkill and won't bend or break. You could easily find a few dozen other OTS material solutions that would also suffice.

True, but since it does not bend, all of the ball's energy will transfer right into your frame. Will your bot tip over? With some reasonable assumptions I think you could do a nice Physics inelastic collision calculation here.

[Caleb Sykes]

Well, there sort of are four of them.

To what are you referring?

[waialua359]

Well, there sort of are four of them.

Yes....and we are building with that in mind.;)

[Jon Stratis]

It's legal. The rule makes no requirement that the virtual cylinder remain fixed relative to the robot. An infinitely thin post with an infinitely thin 6" long stick rotating about a pivot on it satisfies all of the rules. The virtual cylinder will simply oscillate back and forth, with the vertical pole moving from one edge to the other and back.

Check out Q177 in the Q&A: https://frc-qa.usfirst.org/Question/177/a-robot-is-in-the-goalie-zone-with-a-blocking-mechanism-that-obeys-g23-an-opposing-robot-shoots-for-the-high-goal-and-the-ball-bounces-off-the-blocking-mechanism-is-this-a-violation-of-g12-if-the

Generally, if the MECHANISM is in motion relative to the ROBOT at the time of impact, it is "launching" and thus POSSESSION. If the MECHANISM is not in motion relative to the ROBOT, it is considered "deflecting" and not POSSESSION.

So while a contraption that spins around to create an effective block area >6" might be legal, it would be subject to a technical foul every time it actually worked to block a shot!

[JamesCH95]

True, but since it does not bend, all of the ball's energy will transfer right into your frame. Will your bot tip over? With some reasonable assumptions I think you could do a nice Physics inelastic collision calculation here.

Alternatively: you could rely on your mechanism or robot structure reacting off of the player station wall to prevent your robot from tipping over.

[markmcgary]

It's legal. The rule makes no requirement that the virtual cylinder remain fixed relative to the robot. An infinitely thin post with an infinitely thin 6" long stick rotating about a pivot on it satisfies all of the rules. The virtual cylinder will simply oscillate back and forth, with the vertical pole moving from one edge to the other and back.

I'm not sure if this statement plays nicely with Q116 (https://frc-qa.usfirst.org/Question/116/in-g23-it-talks-about-breaking-the-6-cylinder-as-a-penalty-if-we-have-an-arm-that-deflects-when-struck-by-a-ball-but-then-returns-after-contact-it-that-a-penalty)?

[Madison]

I'm not sure if this statement plays nicely with Q116 (https://frc-qa.usfirst.org/Question/116/in-g23-it-talks-about-breaking-the-6-cylinder-as-a-penalty-if-we-have-an-arm-that-deflects-when-struck-by-a-ball-but-then-returns-after-contact-it-that-a-penalty)?

There's certainly potential for a device like that to get you into trouble. A distinction should be made, however, between how a device operates and how it is used.

Edit -- I thought you linked to the same Q&A as Jon did -- https://frc-qa.usfirst.org/Question/177/a-robot-is-in-the-goalie-zone-with-a-blocking-mechanism-that-obeys-g23-an-opposing-robot-shoots-for-the-high-goal-and-the-ball-bounces-off-the-blocking-mechanism-is-this-a-violation-of-g12-if-the, but you did not.

For what it's worth, the Q&A you've linked to here -- 166 -- has no bearing on the legality or function of a spinning blocker.

[markmcgary]

For what it's worth, the Q&A you've linked to here -- 166 -- has no bearing on the legality or function of a spinning blocker.

I re-read your post and I agree with you. Said device is legal and would remain so unless and until future interaction with a ball caused it to deflect outside of the 6" cylinder. In order to comply with Q116, said device would have to be infinitely rigid to remain inside the 6" cylinder when reacting to the force of a impelled ball striking the device.

[Madison]

I re-read your post and I agree with you. Said device is legal and would remain so unless and until future interaction with a ball caused it to deflect outside of the 6" cylinder. In order to comply with Q116, said device would have to be infinitely rigid to remain inside the 6" cylinder when reacting to the force of a impelled ball striking the device.

Well, sufficiently rigid, not infinitely so. :)

[gpetilli]

There's certainly potential for a device like that to get you into trouble. A distinction should be made, however, between how a device operates and how it is used.

Edit -- I thought you linked to the same Q&A as Jon did -- https://frc-qa.usfirst.org/Question/177/a-robot-is-in-the-goalie-zone-with-a-blocking-mechanism-that-obeys-g23-an-opposing-robot-shoots-for-the-high-goal-and-the-ball-bounces-off-the-blocking-mechanism-is-this-a-violation-of-g12-if-the, but you did not.

For what it's worth, the Q&A you've linked to here -- 166 -- has no bearing on the legality or function of a spinning blocker.

Yes, there is a distinction between operation and usage, but I think the device under consideration would be constantly spinning (not necessarily under software control) to increase the effective volume. The way I read Q177 is that if you have a spin-able blocker and locate it in the path of the ball, it is legal as long as it is not moving (w.r.t robot) at the time of impact. If it is constantly spinning, it will launch (possess) the opponent's the ball and incur a foul at time of impact. Am I missing something?

That said, if the robot itself was in a death spiral and the blocker was not moving w.r.t the robot, that would be legal - as long as the robot is in constant contact with the goal.

[Caleb Sykes]

I feel like a spinning tall blocker that is hit by an incoming ball would not be considered "launching" the ball because "launching" requires "impelling a ball to a desired location or direction". I don't think that a freely spinning blocker that is hit by a ball meets this requirement.

Let's say that I am a goalie in a soccer game. I run around in a circle in front of the goal at a constant speed with my eyes closed. An opponent shoots the ball at the goal and the ball bounces off of me at some arbitrary angle. Would anyone say that I had "impelled the ball to a desired location or direction"? I certainly wouldn't.

Back to Aerial Assist. A tall blocker is spinning on top of a robot. An opponent shoots the ball at the goal and the ball bounces off of the blocker at some arbitrary angle. The tall blocker is certainly in motion relative to the robot, but the goalie robot has not impelled the ball to a desired location or direction. Hence, this robot does not "launch" the ball and should not receive a penalty.

[BigJ]

I feel like a spinning tall blocker that is hit by an incoming ball would not be considered "launching" the ball because "launching" requires "impelling a ball to a desired location or direction". I don't think that a freely spinning blocker that is hit by a ball meets this requirement.

Let's say that I am a goalie in a soccer game. I run around in a circle in front of the goal at a constant speed with my eyes closed. An opponent kicks the ball at the goal, and the ball bounces off of me. Would anyone say that I had "impelled the ball to a desired location or direction"? I certainly wouldn't.

Back to Aerial Assist. A tall blocker is spinning on top of a robot. A ball comes close to the blocker and bounces off at some arbitrary angle. The tall blocker is certainly in motion relative to the robot, but the goalie robot has not impelled the ball to a desired location or direction. Hence, this robot does not "launch" the ball and should not receive a penalty.

One could argue "away from the goal" is a desired direction.

[JamesCH95]

Rather than rotating the blocker about an axis inside the 6in cylinder, rotate the blocker about an axis outside of the 6in cylinder. Imagine a 6in diameter tube on the edge of a lazy Susan.

I'm sure there's a way to use a spirograph-like mechanism to further increase the effective blocking area of any proposed device, more complex than a lazy Susan, but a much bigger wow factor.

Details are left to the reader as an exercise.

['lil robo-girl]

I like the rotating idea, but for our team, the main dilemma is how to get it up there without swinging out. In the case of a spinning plate, how would you go about that? (There's about a two foot difference between how high you can be out of the goalie zone, and the middle of the goal. See rule G22.)

[Jared Russell]

Well, there sort of are four of them.

You have a different definition of "safe" than I do.

[Descartes2.0]

We discussed using high speed alternating rotating hockey sticks at an angle keeping it within the 6 in. column. When one stick is in the air, the other is was down and on the way back up. If spun fast enough, and weighted properly, you can essentially make a 24 in. wide defense mechanism.

[JamesCH95]

I like the rotating idea, but for our team, the main dilemma is how to get it up there without swinging out. In the case of a spinning plate, how would you go about that? (There's about a two foot difference between how high you can be out of the goalie zone, and the middle of the goal. See rule G22.)

Like I said earlier, 2ft-3ft stroke air cylinders are OTS from McMaster Carr. You could use an air cylinder to directly deploy a 'blocker' element.

As for spinning, I would look at a Lazy Susan bearing from AM or McMaster, and think about how I could drive it with gears or chains+sprockets.

There are about a thousand different ways to make this mechanism, you'll have to decide what's best for your team.

[gpetilli]

Like I said earlier, 2ft-3ft stroke air cylinders are OTS from McMaster Carr. You could use an air cylinder to directly deploy a 'blocker' element.

As for spinning, I would look at a Lazy Susan bearing from AM or McMaster, and think about how I could drive it with gears or chains+sprockets.

There are about a thousand different ways to make this mechanism, you'll have to decide what's best for your team.

James,
I think the language the game design committee used for the answer to Q177 is very clear that a spinning Lazy Susan will draw fouls. Please re-read their ruling below:

"Generally, if the MECHANISM is in motion relative to the ROBOT at the time of impact, it is "launching" and thus POSSESSION. If the MECHANISM is not in motion relative to the ROBOT, it is considered "deflecting" and not POSSESSION."

[JamesCH95]

James,
I think the language the game design committee used for the answer to Q177 is very clear that a spinning Lazy Susan will draw fouls. Please re-read their ruling below:

"Generally, if the MECHANISM is in motion relative to the ROBOT at the time of impact, it is "launching" and thus POSSESSION. If the MECHANISM is not in motion relative to the ROBOT, it is considered "deflecting" and not POSSESSION."

Good to know. Thank you for posting.

[Erobot]

The top of the goal is about 10ft high but the center of the goal is about 8ft high. The ball is 2ft and the goal opening is 3ft 1in. :D the 1in makes me laugh.
Anyways, Do the math, to block a high goal shot you only need a 3ft extrusion for a 5 ft robot of course. ;) That sound more do able. Through my experience last years game clarified the vertical cylinder rule for climbing the pyramid, right? if the contact with the ball rocks the whole robot the vertical cylinder should rock with it to, right?:eek: ::rtm:::yikes:

[MooreteP]

The top of the goal is about 10ft high but the center of the goal is about 8ft high. The ball is 2ft and the goal opening is 3ft 1in. :D the 1in makes me laugh.
Anyways, Do the math, to block a high goal shot you only need a 3ft extrusion for a 5 ft robot of course. ;) That sound more do able. Through my experience last years game clarified the vertical cylinder rule for climbing the pyramid, right? if the contact with the ball rocks the whole robot the vertical cylinder should rock with it to, right?:eek: ::rtm:::yikes:

Considering the trajectory of the ball, it could be even lower, though not by much.

During match play, since most balls will be launched from a low position, a 5' robot could position themselves in front of a launcher to stop a 10 point goal shot.

I stated in another thread that I fear the 10 point goal may become an orphan over time.

[cdizzle]

Is there any rule that prevents the opposing team from being in the goalie zone or contacting a robot that is in the goalie zone?

[JohnSchneider]

Is there any rule that prevents the opposing team from being in the goalie zone or contacting a robot that is in the goalie zone?

Not that I can find, and also nothing about contact with that robot in auto. Goalie zones are not "protected" zones.

['lil robo-girl]

Here's a basic, horizontal, larger than it will be version of our plan.

http://www.youtube.com/watch?v=O0GUZ9lFZrk&feature=youtu.be