Chief Delphi - Grappling hook?

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- - Grappling hook? (http://www.chiefdelphi.com/forums/showthread.php?t=80003)

Sean Raia

12-01-2010 10:13

Grappling hook?

Is it possible to have a hook shoot up at an angle with strong rope attached and latch on to the tower (assuming its in the height limits). then is it possible to reel the rope in?

This is just an idea our team has had and im wondering if it can be accomplished.

vg674

12-01-2010 10:25

Re: Grappling hook?

The only problem I would see is with the entanglement of robots or being hazardous to people. Rules <R03> to <R06> seem to say that it is essentially too dangerous to do so, and understandably so. I can only imagine a grappling hook shooting the wrong way and ramming into players or refs or destroying the field... not so great. Good idea though!

Sean Raia

12-01-2010 10:26

Re: Grappling hook?

Yeah that was one of our concerns, and i doubt we will be using the grappling hook idea. But would it be possible to shoot the grappling hook out or reel the rope in and lift a 120 pound robot in the first place?

I want to know weather or not we should consider it as a plausible idea.

nnfuller

12-01-2010 10:36

Re: Grappling hook?

From:
http://www.chiefdelphi.com/forums/ne...reply&p=897181

Quote:

Originally Posted by Kevin Sevcik (Post 897181)

To bring a little more "training" to the discussion... you just have to look at the maximum power of your motors to determine the absolute fastest you can get a robot up.

Power = Work / Time
Work = Force * Distance
so
Power = Force * Distance / Time
or
Power = Force * Speeeeeeeed

The CIM motors max out at 343W = 252 lbf*ft/s

So the fastest an optimally geared CIM will lift a bot is about 1.5 ft/s. Or you lift in about a second.

Mind, this assume you're instantly at the max power point, no friction losses, spherical chickens, the works. But, lifting your robot 20" in, say, 5 seconds is easily doable if you gear it right. The gearing it right being key. Max power occurs at 1/2 stall torque. But I'd really aim for 1/4 - 1/3 stall torque for your full load, for safety and losses and all that.

vg674

12-01-2010 10:36

Re: Grappling hook?

With the right material, I would say that that wouldn't be a problem at all. There are many ways to lessen the strain, and I think it would be quite easily possible to engineer a way, be it pulleys or a fancy combination of motors to use a grappling hook to hang from the bar, and even great in the respect of not needing power while removing the robot. Again, I see the main concern as safety, and I think that will be the deciding factor.

JohnFogarty

12-01-2010 10:43

Re: Grappling hook?

We thought of this exact thing as well last night. Though we may have an idea on how to control it.

JIMBO4341

12-01-2010 10:45

Re: Grappling hook?

I don't think this is possible as I think it's likely that you would exceed your vertical allowance. The bars are 84'' high your maximum is 90'' so there's only 6 inches of leeway for your shot to fly over the bar and grapple. Also if you happen to miss you would almost surely exceed your horizontal allowance. They teased us with the grapple bot in the kickoff video :( .

roborat

12-01-2010 10:46

Re: Grappling hook?

I saw several bots hang in 04 using hooks but the all had some type of arm extend up with hook on end to catch the bar and the hook and cable were velcroed so they would release from the arm and winch up the bots. Only purpose of the arm was to place the hook.

JohnFogarty

12-01-2010 10:48

Re: Grappling hook?

make sure the cable atached to your grapple is shorter than what the max is.

coldfusion1279

12-01-2010 10:54

Re: Grappling hook?

There are ways of using cables without "shooting" them up there. A shot is also inaccurate, dangerous, and possibly could go over the height limit... Try and think of more controlled ways to have a hook go up... you're on the right track with cables...

Sean Raia

12-01-2010 12:13

Re: Grappling hook?

I think our team is actually going with a scissor lift mechanism with hooks on the top. we want to be able to go under the tunnel. I just thought the grappling hook was a neat idea for discussion, and im from what i read its possible and legal if it doesn't go outside the dimensions.

viperred396

12-01-2010 12:25

Re: Grappling hook?

we decided to opt out of the hook because the max hight during FInal Configuration is 90 in and the towers height is 84 in so the hook only has 6in to make it over and we didn't want to risk going to high.

<G40> also might say its a no go because of the entanglement issue

edit: sry i re-said things others did i didn't notice them until i reread the thread

Al Skierkiewicz

12-01-2010 14:03

Re: Grappling hook?

Of course you can lift a robot using a hook and cable as described. We have done it. There will some risk involved this year...

<G31> BALL RETURN and RETURN BARS Protection - ROBOTS may not contact the BALL RETURN or the RETURN BARS (black tape). Violation: PENALTY for inadvertent contact; plus a RED CARD for obviously intentional contact or damaging contact.

bobmonkey836

12-01-2010 14:37

Re: Grappling hook?

Quote:

Originally Posted by Sean Raia (Post 897368)

it's very plausible. if you could get the accuracy, you should have the strength pretty easily after that. after all, mountain climbers+ gear tend to be well over 120 lbs, and those ropes will easily hold the weight.

Mr_I	12-01-2010 14:46

Re: Grappling hook?

Quote:

Originally Posted by roborat (Post 897386)

Case in point, Team 811:

The black pole on the right telescoped out ~15 feet to put the grappling hook over the 10' chin-up bar, and then a window motor (legal then) pulled Red Streak II into the air v-e-r-y s-l-o-w-l-y .

Al Skierkiewicz

12-01-2010 15:09

Re: Grappling hook?

Quote:

Originally Posted by bobmonkey836 (Post 897533)

after all, mountain climbers+ gear tend to be well over 120 lbs, and those ropes will easily hold the weight.

Look up spectra cable and be shocked and awed. We have used it for many years including last year.

viperred396

12-01-2010 16:15

Re: Grappling hook?

Quote:

Originally Posted by bobmonkey836 (Post 897533)

I remember reading somewhere that after hanging a large weight from one of those ropes you shouldn't use them again because they might break. even if it hold during testing and the practice matches but then it might break in the qualifiers causing you to lost

elmer_fud

14-01-2010 01:51

Re: Grappling hook?

Quote:

Originally Posted by viperred396 (Post 897591)

I think climbing rope will be overkill. A climbing rope will require something over 1000 pounds to break. Some parachute cord (1/8 in rope) has a breaking strength of 300 lbs but you would likely break this using it with a 150 lb robot. I think something in the area of 3/8 inch rope would work well

With climbing rope you are not supposed to use it again after a hard fall ( several feet) because it is weakened. Putting 150 lbs on it repeatedly will not hurt the rope.

references
parachute cord http://www.rei.com/product/784296

climbing rope http://www.backcountry.com/outdoorge.../EDL0009M.html (9kn is about 2000 lbf)

Dick Linn

14-01-2010 11:29

Re: Grappling hook?

1 Attachment(s)

Quote:

Originally Posted by roborat (Post 897386)

Team 975 used a telescoping tube made from nested PCV pipes. There were flat-wound clock springs to extend the arm segments and a small steel cable/winch to control extension and lift, and a hook on the end that was loosely attached. It worked fairly well. In one match at the VCU regional, all four robots were hanging from the bar. That year's robot was unofficially named "hooker".

It's the lowest one in the foreground. (Check out the officials in the background - everyone went wild.)

http://www.chiefdelphi.com/forums/at...d=126348704 6

Joey P

14-01-2010 11:45

Re: Grappling hook?

Yea I don't think that the Grappling Hook would be such a good idea for this game, but in general it is a good thought. Maybe it can be used in a game in the next few years but I wouldn't for this because it would be dangerous. Plus, what if your hook missed the pole and it latched onto the ball return rack, It could destroy the return rack, which would not be good for your team or the actual competition.

Edoc'sil

14-01-2010 15:12

Re: Grappling hook?

Quote:

Originally Posted by Sean Raia (Post 897441)

I would be wary of this idea, w tried to do this a few years back lifting just a few pounds and ours totally failed. If you do decide to do this just consider that the lower the lift gets the worse the mecanical disadvantage gets.

AdamHeard

14-01-2010 15:39

Re: Grappling hook?

Shooting a grappling hook might be unreliable just from a rules standpoint; you can't exceed 90" tall, and the bar is 84" tall, that's a very small margin for error on a shot.

Callbt

14-01-2010 17:47

Re: Grappling hook?

Can you use a "pole climber" to place the hook at top and then winch the cable/rope back in?

EricH

14-01-2010 18:00

Re: Grappling hook?

Quote:

Originally Posted by Callbt (Post 899192)

Can you use a "pole climber" to place the hook at top and then winch the cable/rope back in?

Nothing against it.

However, there is one thing that a LOT of robots had in common in 2004: If, for some reason, their hook came off it's pole, it was impossible, or close to it, for them to try again. This led to a number of hooks dragging on the floor. I remember one match where a team's "pole climber" hook got stuck in my team's lift's lightening holes, which were admittedly rather big, but it was just bad luck there. They'd managed to drop the hook, too, so they were stuck for the duration of the match.

My team never had to worry about that; our policy of "All deployables shall be retractable" plus a key design feature we had had led us to have a very solidly attached single-tooth hook fixed to the top of our lift, so no deploying that one...

Brandon_L

26-01-2010 16:05

Re: Grappling hook?

Quote:

Originally Posted by Mr_I (Post 897543)

Case in point, Team 811:

The black pole on the right telescoped out ~15 feet to put the grappling hook over the 10' chin-up bar, and then a window motor (legal then) pulled Red Streak II into the air v-e-r-y s-l-o-w-l-y .

Window motors arn't legal this year?

EricH

26-01-2010 16:55

Re: Grappling hook?

Quote:

Originally Posted by Brandon_L (Post 907320)

Window motors arn't legal this year?

Sometimes they are, sometimes they aren't. This year, there happen to be 4 in the KOP, 2 LH and 2 RH. That means that those 4 (or exact replacements) are legal, but any others that are on the robot are not.

Mr_I	26-01-2010 16:59

Re: Grappling hook?

Quote:

Originally Posted by Brandon_L (Post 907320)

Window motors arn't legal this year?

My apologies! I meant to say "van door motor". (Too many details from too many years ...):rolleyes:

Andrew.Jensen

27-01-2010 20:18

Re: Grappling hook?

We thought about this idea, but we realized it was impractical for a few reasons. One is that the precision needed to latch onto that tower without going past the hight limit is ridiculous. You'd have to time to hook and measure it so it reaches the maximum of its arc about three inches above the bar. Also, the reeling in doesn't seem so practical, especially because the grappling hook might break. Finally, I think FIRST does not allow shooting things, or at the least they frown on it. Well, good luck with your idea if you use it.

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