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-   -   Fans for defense (http://www.chiefdelphi.com/forums/showthread.php?t=76375)

mikekim 31-03-2009 17:20

Fans for defense
 
Just wondering if any teams have tried to use a high power fan system defensively in this competition.

Daniel_LaFleur 31-03-2009 18:13

Re: Fans for defense
 
Quote:

Originally Posted by mikekim (Post 843912)
Just wondering if any teams have tried to use a high power fan system defensively in this competition.

Yes we (1729) did ;)

If you want the specs, PM me.

Alex_2487 31-03-2009 18:15

Re: Fans for defense
 
we considered using one but decided not to based on the fact that the balls have large holes in them.

edit: i just realized the mike from my team is the starter of this topic

Dantvman27 31-03-2009 18:21

Re: Fans for defense
 
We did and they worked great, if done right. We were able to get between a robot and its trailer, turn on the fans and push a team halfway down the field by its trailer. Theres alot more to building the fans than just slapping a motor on a blade. My team did alot of research

heres a video of them running in the pit
http://www.youtube.com/watch?v=Xnw7ieccNNc

martin417 31-03-2009 18:40

Re: Fans for defense
 
It depends on what you mean by "defense". We had two FP driven propellers on our bot that provided 6-8 lb.s of thrust. At one point, when our ball intake broke, our driver pushed 1319 (flash) all the way down the field sideways, to the human player, who then scored two super cells.

If, on the other hand, you mean using an air stream to deflect orbit balls, then no. We did some experimentation using a 3 hp leaf blower. While you could push the orbit balls around on the ground easily enough, we were not able to change the trajectory of an incoming orbit ball enough to make much difference. We decided that it wasn't worth pursuing.

XXShadowXX 31-03-2009 20:21

Re: Fans for defense
 
I know the robodawgs were trying, but i saw one of their team members walking around with it (wired to a switch and a battery in his backpack), it made a huge amount of thrust, but i really never saw it work.

Jetweb 31-03-2009 20:33

Re: Fans for defense
 
A bunch have tried. my favorite is 180, basically you went where they wanted you to go. On another note with our basket dumper we cant dump on them while this fan is running (from directly behind). You can throw balls in to the trailer though


Zflash 31-03-2009 20:51

Re: Fans for defense
 
Quote:

Originally Posted by martin417 (Post 843948)
It depends on what you mean by "defense". We had two FP driven propellers on our bot that provided 6-8 lb.s of thrust. At one point, when our ball intake broke, our driver pushed 1319 (flash) all the way down the field sideways, to the human player, who then scored two super cells.

First let me say congrats on the win and building a great robot.

Second I feel I have to mention that I believe you were able to push us that way simply because our driver did not know how to maneuver out of it. Maneuvering out of it would have been possible and he was a rookie driver. The fans had nothing to do with it. Had you tried that again you would not have been as successfull.

and Third if you guys keep posting your different strategies on here people our gonna know what to expect. I would be cool to see a team from the South even if you are on the "wrong side of the border" win it all but that will be more difficult if you don't keep some stratgy up your sleeve. Good luck

roboraven15 31-03-2009 21:07

Re: Fans for defense
 
469 Las Guerillas is using 2 fans for thrust. I'm not sure how well its working i didn't see any huge differences, but it was pretty cool either way, cause they were very little of there weight, so they had a heavy complex shooter and storage aswell.

santosh 31-03-2009 21:13

Re: Fans for defense
 
Quote:

Originally Posted by Zflash (Post 844040)
Second I feel I have to mention that I believe you were able to push us that way simply because our driver did not know how to maneuver out of it. Maneuvering out of it would have been possible and he was a rookie driver. The fans had nothing to do with it. Had you tried that again you would not have been as successfull.

Yeah, but they did it and scored 2 super cells on you...

Zflash 31-03-2009 21:18

Re: Fans for defense
 
Quote:

Originally Posted by santosh (Post 844053)
Yeah, but they did it and scored 2 super cells on you...

I never said that they didn't in fact I agreed that they did. However this thread was about the effects that fans had and I just pointed out that fans had nothing to do with them accomplishing that task.

Akash Rastogi 31-03-2009 21:25

Re: Fans for defense
 
Quote:

Originally Posted by Zflash (Post 844056)
I never said that they didn't in fact I agreed that they did. However this thread was about the effects that fans had and I just pointed out that fans had nothing to do with them accomplishing that task.

Just curious, how would you get out of a situation like that? Hard to see how a pin from 1771 (yeah I watched all their matches) is escapable when they are pushing full force with fans + accelerating. I wanna know how to get out of one of their pins just incase we ever have to face these guys. ;)

sdcantrell56 31-03-2009 21:31

Re: Fans for defense
 
Quote:

Originally Posted by Akash Rastogi (Post 844061)
Just curious, how would you get out of a situation like that? Hard to see how a pin from 1771 (yeah I watched all their matches) is escapable when they are pushing full force with fans + accelerating. I wanna know how to get out of one of their pins just incase we ever have to face these guys. ;)

Akash the secret is that there is no way to escape. When we have our fans going and we're pushing someone, we are accelerating close to %50 faster than any other robots. If you can't accelerate faster than us, which is near impossible to do when being pushed sideways, you are going where ever we want, which just so happened to be in front of our human player. In short a different driver would not have made any difference.

Zflash 31-03-2009 21:32

Re: Fans for defense
 
Quote:

Originally Posted by Akash Rastogi (Post 844061)
Just curious, how would you get out of a situation like that? Hard to see how a pin from 1771 (yeah I watched all their matches) is escapable when they are pushing full force with fans + accelerating. I wanna know how to get out of one of their pins just incase we ever have to face these guys. ;)

Well since there was plenty of field open while they were pushing us then we could have avoided the pin to begin with while they were pushing us toward the wall I am sure you can figure out how that would have worked out. However since you pretty much believe that there is no way out of it then I will not even try to explain it. Also knowing your relationship with 1771 I doubt anything I say would even be belived by you. Somehow this thread has turned into a different topic then previously discussed hope this hasn't affected it too much.

Akash Rastogi 31-03-2009 21:35

Re: Fans for defense
 
Quote:

Originally Posted by Zflash (Post 844066)
Well since there was plenty of field open while they were pushing us then we could have avoided the pin to begin with while they were pushing us toward the wall I am sure you can figure out how that would have worked out. However since you pretty much believe that there is no way out of it then I will not even try to explain it. Also knowing your relationship with 1771 I doubt anything I say would even be belived by you. Somehow this thread has turned into a different topic then previously discussed hope this hasn't affected it too much.

Excuse me? I specifically asked how to get out of one of their pins because I want to know. We've had HUGE problems getting out of pins especially at NJ and PA and I want to know how to get out of pins. For example, 1279 who used fans killed us in Philly quarterfinals by pinning and scoring like crazy and in NJ 2753 and 2344 forced us into pins in the Semi's. Don't assume things because I am friends with them please, I like your team and robot too.

2753 is currently ;) fanless but they pin like mad.

RMS11 31-03-2009 21:39

Re: Fans for defense
 
Having driven against 1771 in 4 matches, with them in about 8, and watched quite a few others, usually their fans seem to help much more with maneuverability rather than pinning. They can make turns much quicker, but in this game pinning is really about positioning. You much kinda wedge your close to their trailer hitch and push at an angle. Other pins usually are fairly easily escapable, fans or no fans. Note the last qualification match of Palmetto, 21 shut down and pinned 1771 and their fans the hole match.
So in conclusion, I have seen fans effective to aid in turning and some acceleration, but dont make a huge difference in terms of pushing and pinning.

Aren_Hill 31-03-2009 21:39

Re: Fans for defense
 
Quote:

Originally Posted by Zflash (Post 844040)
The fans had nothing to do with it.

and Third if you guys keep posting your different strategies on here people our gonna know what to expect.

Its a fairly simple equation, max pushing force of the drivetrain optimized through traction control, plus an additional 7lbs of force...

they will be able to push more than a normal bot theres not really much to argue

and i'm not gonna yell at him for posting strategies, lol :D

Zflash 31-03-2009 21:43

Re: Fans for defense
 
It is hard to get out of a pin in this game, as I said we were not yet pinned while we were being pushed in open field. This is when it is critical to maneuver yourself away before getting pinned between two robots or a robot and a wall. The trick is to recognize exactly when you are getting pushed and to start turning out of it by turning your left side fwds and your right side backwards if you are getting pushed on th left side with your trailer behind you. We tried this when we returned to prove it, it is like pushing against a moving wall, and if the opponnent driver does not expect it, it will work. Sorry if I got the wrong impression, and obviously this will not work if you do not have enough manuvering space.

Zflash 31-03-2009 21:45

Re: Fans for defense
 
Quote:

Originally Posted by Aren_Hill (Post 844073)

and i'm not gonna yell at him for posting strategies, lol :D

I hope I wasn't yelling..:ahh:

Aren_Hill 31-03-2009 21:49

Re: Fans for defense
 
Bug him for posting strategies would've been better wording lol sorry bout that

Coley 01-04-2009 09:11

Re: Fans for defense
 
You guys really think he posted all of our strategies? lol you are mistaken unfortunately for you.

martin417 01-04-2009 09:27

Re: Fans for defense
 
Quote:

Originally Posted by Zflash (Post 844040)
and Third if you guys keep posting your different strategies on here people our gonna know what to expect. I would be cool to see a team from the South even if you are on the "wrong side of the border" win it all but that will be more difficult if you don't keep some strategy up your sleeve. Good luck

As much as I enjoy winning, the reason I got into First was to share my experience and hopefully to teach some young people about engineering, as well as inspire them to pursue careers in that field. I understand that is the primary goal of First. If someone asks a question to which I feel I have a good answer, I will answer it to the best of my ability. If they then use that knowledge to create a more effective robot or strategy, then I have already won.

Remember, "knowledge shared is power squared" (not sure who originally said that).

Zflash 01-04-2009 09:39

Re: Fans for defense
 
Quote:

Originally Posted by Coley (Post 844288)
You guys really think he posted all of our strategies? lol you are mistaken unfortunately for you.

I never said that he posted all of your strategies I just suggested that you all keep something to yourself. It is not unfortunate for me or my team because we will not be attending the championships thus we will not be competing against you again, that is what is unfortunate. I was merely suggesting to not post your strategies until the game has been played out, however you are more then welcome to do as you please. That is what is great about the United States of America ... free speech. By the way I don't think it is unGP to hold strategies to yourself, maybe I'm wrong.

ScottOliveira 02-04-2009 14:22

Re: Fans for defense
 
I didn't see anyone post the obvious strategy as far as escaping a pin -> get your alliance partners to help! Teamwork pretty much always wins ;).

As for the original post, fans on defense, not only is it hard to make them powerful enough to be effective, but it is hard to angle them correctly. Any fan pointed at any angle other than parallel with the ground would change the normal force on the bot, which could cause it to be ruled a traction device in violation of R06 (I'm not 100% sure on whether it would qualify, but I believe I recall a GDC post about altering air pressure to increase traction, again, not 100%).

EricH 02-04-2009 14:31

Re: Fans for defense
 
Quote:

Originally Posted by ScottOliveira (Post 845009)
As for the original post, fans on defense, not only is it hard to make them powerful enough to be effective, but it is hard to angle them correctly. Any fan pointed at any angle other than parallel with the ground would change the normal force on the bot, which could cause it to be ruled a traction device in violation of R06 (I'm not 100% sure on whether it would qualify, but I believe I recall a GDC post about altering air pressure to increase traction, again, not 100%).

It qualifies. There's one about using fans and vacuums to increase the normal force/traction characteristics.
http://forums.usfirst.org/showthread.php?t=11025

ScottOliveira 02-04-2009 14:47

Re: Fans for defense
 
Thanks for the link Eric. Knew I had seen a post, but couldn't remember exactly ;).

MikeReilly 02-04-2009 18:40

Re: Fans for defense
 
Not to slam a team that we pinned, whatever. I'll try to find the video of the match where our team was pinned by two bots, one on each side, and pulled out of it. That was cool.

boomergeek 02-04-2009 21:16

Re: Fans for defense
 
Quote:

Originally Posted by MikeReilly (Post 845102)
Not to slam a team that we pinned, whatever. I'll try to find the video of the match where our team was pinned by two bots, one on each side, and pulled out of it. That was cool.


We used FP motors and followed 1771 recommendation on the nuances of the shroud shape: We could push any bot. We put our fans on a turret and varied them between 75% and 100% power in our final two matches. The fans properly used have a dramatic impact. I have no concept of how an expert driver could possibly avoid a pin unless she/he gets their alliance bot to run intentionally run interference: we were faster, more manueverable and could push stronger.

If I could start over, then I would recommend a 4 wheel drive train and at least 15 lbs of thrust from four fans on a turret. Turn it into Sumo bot wrestling. Easy pushes and excruciatingly long pins in front of alliance human shooters.

I might even throw in a compressor/tubing and solenoids to rapidly puff air to keep the traction wheels and the regolith in front of them free of dust to improve traction. Ball manipulation would be completely optional/superfluous.
:P
http://www.chiefdelphi.com/media/photos/33618

martin417 03-04-2009 08:00

Re: Fans for defense
 
I hope that no-one took my comments as a slam against ANY team, certainly not 1319. You guys built an awesome bot, and we enjoyed watching and playing with/against you at Peachtree and Palmetto. You guys were deserving of the quality award at Peachtree, as well as the judges award at Palmetto. I only singled you out as an example of using the added thrust of propellers as defense (the whole point of this thread). I still believe that the play in question was not the fault of your driver, or your robot. The added 6-8 Lb.s of thrust from the propellers gave our bot the strength and speed necessary to push a robot sideways all the way down the field.

Zflash 03-04-2009 08:02

Re: Fans for defense
 
Good luck at the champs 1771.

ScottOliveira 03-04-2009 14:07

Re: Fans for defense
 
Quote:

Originally Posted by boomergeek (Post 845164)
We used FP motors and followed 1771 recommendation on the nuances of the shroud shape: We could push any bot. We put our fans on a turret and varied them between 75% and 100% power in our final two matches. The fans properly used have a dramatic impact. I have no concept of how an expert driver could possibly avoid a pin unless she/he gets their alliance bot to run intentionally run interference: we were faster, more manueverable and could push stronger.

If I could start over, then I would recommend a 4 wheel drive train and at least 15 lbs of thrust from four fans on a turret. Turn it into Sumo bot wrestling. Easy pushes and excruciatingly long pins in front of alliance human shooters.

I might even throw in a compressor/tubing and solenoids to rapidly puff air to keep the traction wheels and the regolith in front of them free of dust to improve traction. Ball manipulation would be completely optional/superfluous.
:P
http://www.chiefdelphi.com/media/photos/33618



Interesting idea with the turret. Out of curiosity, what kind of turning speed do you have on it, and what angles can it reach? Is it a fully rotational 360, or do you have a limit on it? Also, how high do you have the turret mounted? While it doesn't matter quite as much with the trailer, I would think having rotating fans set up high would create a tipping hazard.

And that's an interesting idea about using a compressor to puff air in front of the wheels. Has that been tried by anyone? I'm curious about what gains you would see from that.

boomergeek 03-04-2009 16:15

Re: Fans for defense
 
Quote:

Originally Posted by ScottOliveira (Post 845406)
Interesting idea with the turret. Out of curiosity, what kind of turning speed do you have on it, and what angles can it reach? Is it a fully rotational 360, or do you have a limit on it? Also, how high do you have the turret mounted? While it doesn't matter quite as much with the trailer, I would think having rotating fans set up high would create a tipping hazard.

And that's an interesting idea about using a compressor to puff air in front of the wheels. Has that been tried by anyone? I'm curious about what gains you would see from that.

The turret (powered be the mabuchi) could go about from -135 degrees to +135 degrees in about a 1.5 seconds. The fans are centered about 48 inches off the ground and overall we had a very low (and very central) center of gravity: there was not any tipping danger in our configuration.
The trailer and the rectangle wheel base makes it difficult to envision a significant tipping danger.

I have not seen the compressor puffing tried, but I saw one team with paint brushes to clean wheels and another team that won an award at the Connecticut Regional for an innovative way of keeping their wheels clean (I did not see or hear about their actual configuration). Those teams got me thinking: why not clean the wheels and the path at the same time for even better results.

Keeping the dust off wheels definitely helps with traction especially after the crater has been used a few times. Cleaning wheels between matches certainly helps.

We aren't going to nationals but its hard to ween myself off this challenge.:o


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