Air Defense System
 

Hi everyone,

My team was brainstorming ideas for our robot's role in the game, and one thing we thought of was a defensive robot that used an air cannon or fan to knock balls off their trajectory.

This seems like a logical thing to do, since when you're playing defense you will be shorter than the opponent that is scoring.

I could not find anything in the rules that would outlaw this besides
G13, which says that "Basketballs may not be intentionally placed out of bounds," and under
Robot 4.1.8 Motors and Actuators which states that "The only motors and actuators permitted on 2012 FRC Robots include: (K.) drive motors or fans that are part of a speed controller or COTS computing device."

Although, R71 says that "For the purposes of the FRC, the following devices are not considered pneumatic devices and are not subject to pneumatic rules (though they must satisfy all other rules): a device that creates a vacuum,...", so we could potentially use a vacuum to achieve the same purpose.

So, would this be an illegal tactic? Is it within the spirit of the game?

Thanks!

Re: Air Defense System
 

We are thinking the same thing. the kids looked up quite a few different focused air blast technologies last night.

Re: Air Defense System
 

as a joke what about attaching a big piece of plywood onto your robot so that you can block shots.

Re: Air Defense System
 

This could make for some boring matches...

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We joked about this idea, and playing the "Fus Roh Dah!" clip from Skyrim every time it fires.

Re: Air Defense System
 

Not necessarily, it could be the last shot of a Red 102 - Blue 103 game, Red is attempting a shot, and its up to the Blue Air Defense bot to save the team!

It'd be ironic if it assisted the shot into the top basket, and tragic.

Re: Air Defense System
 

I giggled at this one. But what our team was thinking about is a big deployable net, much like a ship's sail, to interfere, which would also collect balls for us to shoot, in addition to our other collection system.

Re: Air Defense System
 

It would be Team 20 pioneering this idea :P

I have my doubts of how effective it would be in an actual match, as the same strategy was brought up in 2006, but it never came to fruition for any team because it just isn't a practical blocker. But try it out, let us know how (if at all) it works.

Re: Air Defense System
 

Are there any videos of teams attempting this from 06?

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G20 says you can't be above 60" when defending, so this strategy might not be so useful for blocking anything above the bottom goal.

Re: Air Defense System
 

which is exactly why we decided on the air defense method, we just need to know if it is illegal or not in the spirit

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I agree, the pneumatics can only shoot at 60 psi and considering the weight of the ball, that may not be enough

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I cannot see this being ruled as illegal or not in the spirit of FIRST.
What i CAN see is this not working, at all. Please, prove me wrong, i'd love to see a robot like this on the field. :)

Re: Air Defense System
 

What would you use to generate an updraft?

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So you need to have enough air to deflect a ball that is at least three feet above you and moving. Gonna be a heck of a fan.

Re: Air Defense System
 

Not that I know of because as I said, no teams attempted it in competition. There was a similar thread on Delphi back then, but for most it never made it past the concept stage, and the teams who prototyped it found it wasn't working as well as they wanted.

Remember, the balls are going to be traveling at a relatively fast rate of speed. In order to change their momentum, it will take a lot of work. If you think of physics W = f * d, you'll need a considerable force (f) for such a short distance (d) window. If anyone wants to pursue this, most certainly don't let me stop you. However I would suggest that no one put all their eggs in this basket, as it may not work out as well as you'd hope. Good luck!

Re: Air Defense System
 

pneumatic cannon, i think fans are illegal under Robot 4.1.8 Motors and Actuators,
or maybe a vacuum, that is exempt

Re: Air Defense System
 

Thanks! We'll keep that in mind, after posting reading these responses I'm having doubts about its effectiveness but we'll still try it on the side

Re: Air Defense System
 

If you switch out the motors on a vacuum or fan you could use it.

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We are allowed 22 motors this year...

Re: Air Defense System
 

Indeed we are. I guess i don't see your point? :confused:

Re: Air Defense System
 

I think blayde is trying to insinuate you can throw multiple motors at a hypothetical vacuum/fan solution.

At the same time, I'd say the free speeds of many of those motors would make them unsuitable for the task (consider the copious amounts of window motors in the mix).

Re: Air Defense System
 

This seems very difficult with the tiny air compressor and limited battery life. I fly lots of quad copters and even the huge amount of wind a 10" prop at significant RPM puts out with a brushless motor wouldn't make a huge impact on the ball at 3'

-Mike

Re: Air Defense System
 

Fans are not illegal, please quote where you thing they are.

A pneumatic cannon would be difficult with the small valves we use.

Re: Air Defense System
 

I do not see anything in the rules that would directly prohibit a team putting a swamp-boat esque shrouded fan powered by a cim on the top of their robot pointing directly up (or at an angle maybe 20 degrees from vertical). A 20" diameter fan powered by 2 cims would be.... scary. Possibly effective, but i'd have to see a prototype. As a hunch though, i'd say it'd be very effective at blocking the middle tier goals, but probably ineffective at changing the path of balls aimed at the top tier goals (unless you're right in front of the robot lobbing for the top rung and can impact the balls motion right as it leaves the robot)

Re: Air Defense System
 

You don't want it to point up, you want it to point slightly to one side. Pushing the ball up may not cause a miss (it just falls into the basket from a higher point). Pushing the ball to the side will disrupt the intended trajectory in both azimuth and elevation, and make it more likely to miss.

Re: Air Defense System
 

Pointing it up could actually assist the ball into the hoop if you're unlucky

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So instead of air, uses balls as SAM's (Surface to Air Missile).

Re: Air Defense System
 

If you can hit a ball with another ball, you should:
a. work for NASA and:
b. use your impressive engineering and programming skills to make a killer offensive robot instead of a defensive one.

Re: Air Defense System
 

Also, pushing the balls up may likely push them out of the court, incurring a foul under <G13>.

This makes any uber-fan idea flawed, IMO.

Re: Air Defense System
 

I agree. Even tracking the ball in mid air and predicting where it is going is unbelievable for a highschool student to do. Keep in mind the delay of the camera and you might only get the ball in one frame. You would have to differentiate it from all the other balls on the field and then calculate its projectory, then calculate the angle of the shooter and shoot, all within a split second.


Even with the air idea, not feasible.

Re: Air Defense System
 

971 tested this idea in 2006 and found it was not feasible. The most effective method was an electric leafblower, and that only deflected the balls an appreciable ammount when the stream of air closely tracked the ball for several seconds. You would have to use then best motors in the kit, sacrificing your drive train, to even come close to the power required to achieve this, and even then you would need an incredibly accurate tracking method to make it work. This also means in a volley of 3 balls, you can only deflect one at most due to the time duration of deflecting opportunity

Re: Air Defense System
 

I think we should get a GIANT hair dryer and capture the balls midair with the venturi effect (like ping pong balls on normal hair dryers). LOL:D

and on a realistic note, there was a team with a fan my freshman year (to navigate the lunacy regolith). might have been delphi elite:confused: ? it was a huge (about 2 foot) wooden-bladed fan on the back of the bot with a cage around it. I have not yet picked up one of these "basketballs" so I don't know how dense they are and if a fan could actually affect it:confused: . This would be AWESOME:ahh: but you would need a fan to take up your entire horizontal dimension and probably add a cowling besides to focus the blast/stream. if you had a 2 foot fan you would have 2" all the way around for a cowling I think.

Re: Air Defense System
 

I'd like to see someone try to get a giant fan like that inspected, something tells me that would not be amused, haha

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what if instead of a large fan blowing a 2 foot circle of air, you funnel the air into a thin, long stream and use it more like an air knife, or an air cleaner on production lines. Maybe two 3 foot fans with all of their air angled up into a stream?

Re: Air Defense System
 

Have any of you ever used an AirZooka?

You may want to consider a giant AirZooka.

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I have used a giant one of those (the big trash cans) it just does not produce enough force. It just messes up someone's hair. Nothing else.

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Why are offensive and defensive robots mutually exclusive?

Based on your description, that was likely a different Delphi-sponsored team, Team 45 the Technokats, rather than Team 48 (Delphi Elite).

Re: Air Defense System
 

We tried that too, up to trash can size. Still less effective than the leafblower, and requires impeccable timimg.

Re: Air Defense System
 

They're not; I just meant that the focus should be on the former, not the latter, especially with the hypothetical skill set involved.

We also thought about it.. however this is extremely complicated to do as you will be needing to track and hit a moving object in mid air.

I mean.... shooting a static object is hard enough as is.

Re: Air Defense System
 

Our team experimented with fans today and found that using 6+ of the KoP fans (side by side and in a row) do absolutely nothing to balls passing by them.

It looks like compressed air would be the way to go for this defense method.

Re: Air Defense System
 

Would 11.6cfs (700cfm) do the trick? I believe all you would need is two CIM motors.

Re: Air Defense System
 

The reason we discarded the ball idea was because it means we are limited to 3 intercepting shots (you can only possess 3 balls), whereas the air system would have unlimited ammunition (disregarding battery life etc.), and like Ninja_Bait said, we would go work for NASA :D

A cannon may not be effective enough given the pneumatic parts allowed (valve is too small i hear and the max psi is too low), fans will be hard to make large and safe while effective enough, and leaf blowers have massive draw on battery.

One idea we had like what Spen.M.P. suggested of an air knife was to have an industrial blower that they use for clearing milling machines and the like, for a concentrated stream.

And like davidthefat, Nuttyman54, and Ninja_Bait said, the difficulty of tracking a ball traveling at more than 10 fps with a lagging camera would be incredibly difficult, and you're paying the opportunity cost of the best motors to power a limited range defensive system that may not be able to protect the top hoops, and the amount of training required for drivers could be more than if you trained them to just shoot baskets.

One way to alleviate this is to make a system that shoots a wall of concentrated air up that is say 5 feet wide, with 3 rotating air cylinders like an autocannon that recharge when not firing to increase the rate of fire.
But this goes back to the limitations of the pneumatics allowed.

Re: Air Defense System
 

First, I yield to <G13> The strategy I proposed will quite likely blow every target out of the Field and into the stands. Safety First.

Onward:
Ah, the reason you don't think I already work for such an outfit is what? (Watch the .sigs)

NASA historically doesn't try to hit other things. Other Agencies (SDI, <litany of US DoD orgs> et al) have tried and succeeded to do so, repeatedly.

Deflection (note, not destruction) of a basketball with another basketball using a control system with a 50mS control loop at ~12ft ranges with known targets from a relatively fixed position near those targets should be easier that dropping the same ball into a basket. Such an automated response during tele-op mode is not unreasonable.

Sure, I start with 2 rounds. I can reload, and if my team sees the value, they'll reload me.

And if I am sitting in the opposition's key, I'm at 84in for the sensor, shooter or both.

Of course, if we get it wrong, we drop balls into the opposition goals. How is that scored?


Now we're having fun :)

Re: Air Defense System
 

Did a mentor just seriously suggest that hitting a rapidly moving target by using the provided control and sensors in a FRC environment would be easier than hitting a stationary target? Then rule out the strategy because of the safety concerns regarding a foam ball?

Really?

Re: Air Defense System
 

If you are in the opponent's key, then you are on the carpet on your alliance station's end of the court, and therefore you can only expand to 60 inches as per rule G20.

[G20] (emphasis mine)

"Robots in contact with the carpet on their Alliance Station end of the Court are limited to 60 in tall. Otherwise, Robots are limited to 84 in tall.

Violation: Foul; or Technical-Foul for repeated or continuous violation."

Re: Air Defense System
 

Completely feasible, IMO. It's not a matter of generating tornado-strength winds here, it's simply about generating a directed draft that, for the fraction of a second that the ball is in the jet stream from the fan, apply a force that alters it's momentum to the side by a tiny amount. By the time the ball reaches the next, it'd have moved enough to possibly cause a missed shot.

A similar idea is with making space objects miss Earth; a small force early in flight can cause a huge gap later. For this, the fact that the shots need to be rather precise means that the fact that time in flight is short wouldn't matter if a decent amount of force is applied.

The balls weight will prevent any serious deflection, but a draft from a decently-sized fan (20"?) powered by a few motors should provide quite a bit of push necessary to move anything in it's way.'

Edit: And a brilliant idea just occurred to me: Why not have an active targeting system combined with the air knife idea?
I.E. A giant fan is always running when needed, producing a huge draft, which is then directed into a controlled funnel system that automatically turns towards and directs the air into the path of inbound basketballs. It'd have the force bonus of a funnel while being capable of constantly hitting the ball, drastically increasing the impulse given to the ball, changing it's course.

Re: Air Defense System
 

That's what they do all the time. They hit Mars, the Moon and at least two (?) asteroids with little probes. And the planets are slow and much bigger than the probes, and it's STILL not easy.

As for deflection, I think everyone is overestimating the effects of "tiny" disruptions. If I aimed and shot a ball intended for the middle of a hoop, it has more than 5 inches of tolerance in any direction. If it hits the rim or backboard first, there is still a good chance of it scoring. You can't push it far enough.

Re: Air Defense System
 

I like the idea and in general you only need to impact the trajectory of a ball by a few degrees. We are putting this on our want list and may get to after we bag the robot.

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I love the idea.

Re: Air Defense System
 

I'm a software guy; are we ever serious about hardware? And I didn't say it was easier; but it is a defense mechanism with offensively capable hardware.

Actually, I think I ruled the idea out first on rule <G13>, which has a safety bent to it.

And in response to another post, the key is not carpet, it is HDPE. So if my 'bot is entirely in the opponent's key, it is not on carpet, and can extend to 84inches.

Re: Air Defense System
 

Actually, only the top of the key is made of hdpe, which is protected if your opposition is touching it. The rest of the key is carpeted.

Re: Air Defense System
 

:confused:

The entire key is HDPE. The semicircular velcroed HDPE area is the key. This does not include the rectangular carpet area outlined by the "purely for decoration" tape.

Re: Air Defense System
 

The key in basketball is generally the entire painted area under the basket. The semi-circle is commonly called the "top of the key". My point here is that if they plan to park on the key and extend, all an opponent has to do is drive into them and they would incur a technical foul.

Re: Air Defense System
 

depends, rules G28 and G44 together protect robots in the key and alleys but G45 protects robots from others trying to intentionally incur a penalty

Re: Air Defense System
 

For those of you who doubted my SAM suggestion:

http://www.ustream.tv/recorded/21334084

:)

Re: Air Defense System
 

For those who just want the punch line, begin watching at 38 seconds. This is truly epic.