Sideways Hanging - Yes or No

[Swampdude]

Pretend he's a robot... This was our first thought on how to hang (due to it's efficiency), so I assume many of you are thinking the same thing. But we're preemptively ditching the idea as I'm sure it will knock the tower over and also point load the vertical member beyond yield. Not to mention if your hanging like this and a couple more bots climb aboard. Actually I haven't studied the footing of the tower but it seems like 3 bots piled up on each others back could get pretty far from center on the tower. Seems like it could go over pretty easy. Perhaps the GDC didn't see this coming, but I recommend a ruling on it soon.

FYI - I'm not planning on asking if this is acceptable on the GDC forum thing.

[thefro526]

There was a team in the 2007 FVC game that did the exact same thing. It was a really efficient way to hang, and I thought of applying it to this year's game...

I'd like to think that the GDC designed the tower with this in mind but, I guess if they haven't we'll know soon enough.

[karatekid]

I think you definately need to consider the balance problem-maybe 2 on 1 side and 1 on the opposite side?

[SuperBK]

I don't see why it wouldn't be legal. It doesn't have to lift that high, only enough to get the wheels off the gound, so it won't put that much side stress on the tower.
Brian

[Chris is me]

While there doesn't seem to be anything wrong with it... Why would you hang this way other than the "normal" way? Or other non-normal ways?

[Swampdude]

Originally Posted by Chris is me

While there doesn't seem to be anything wrong with it... Why would you hang this way other than the "normal" way? Or other non-normal ways?

Instead of making an extending arm that goes 7+ feet up to the hang bar you only need to go up 3'. and if you do it right it takes less force to get your bot up in the air. Not to mention you don't have to share the hang bar with anyone. And you could help other bots up easier from this position. And you could in theory get connected faster and elevated faster than extending 7' and pulling the full distance... so lots of reasons. I just don't want the field breaking so I threw it out there before it became a problem later on, or to verify if it's ok (not that this is the place to do that - but I don't have a tims login and I can't ask team questions, plus the answers traditionally take too long).

And yes you could design a gripper that could let go easy enough.

[Jeff Rodriguez]

Originally Posted by SuperBK

I don't see why it wouldn't be legal. It doesn't have to lift that high, only enough to get the wheels off the gound, so it won't put that much side stress on the tower.
Brian

It has to go above the plane of the platform.
From the definitions in 7.2:
ELEVATED: A ROBOT that is completely above the plane of the PLATFORM and in contact with the TOWER shall be considered ELEVATED.

Either way, once you are off the ground its the same amount of force no matter how high you go.

[Kevin Sevcik]

Originally Posted by SuperBK

I don't see why it wouldn't be legal. It doesn't have to lift that high, only enough to get the wheels off the gound, so it won't put that much side stress on the tower.
Brian

Inaccurate, sir. You have to lift your wheels above the platform to be ELEVATED.

As to why do this.... Well this way, you don't have to reach 7 ft in the air to lift. And you can just as easily lift from under the ball return.

The towers shouldn't flip unless you're doing something very wrong. The base plate is an 80" piece of aluminum plate, so it'd extend about 18" out from the tower on each side. A single robot should have difficulty tipping the tower. Front to back, anyways.

As far a strength.... A 150lb robot with an 18" CoG will put a bending load on a tube of about 50% yield, if you only grab one pole. I don't have a convenient calculator at hand for point load crushing force on tubes, but you can reduce the crushing force significantly by simply spreading your "hands" out father.

Finally... It's dirt simple to make a grasping mechanism for this that releases without power. The dude in the video could have managed just as well with a hook for a left hand and a bunch of friction tape.

[Ken Leung]

The Team Drawings in the document section: http://www.usfirst.org/roboticsprogr....aspx?id=16097, specifically TE-10012.pdf within 2010 Team Field Elements.zip, show a version of the tower using 4X4's as the vertical posts.

If these drawings are official, then it seem the GDC did not intend for robots to attach to the towers using the vertical posts. If they did, then these drawings are invalid for the official game.

Someone need to post a clarifying question in Q&A about this.

[Daniel_LaFleur]

Originally Posted by Ken Leung

The Team Drawings in the document section: http://www.usfirst.org/roboticsprogr....aspx?id=16097, specifically TE-10012.pdf within 2010 Team Field Elements.zip, show a version of the tower using 4X4's as the vertical posts.

If these drawings are official, then it seem the GDC did not intend for robots to attach to the towers using the vertical posts. If they did, then these drawings are invalid for the official game.

Someone need to post a clarifying question in Q&A about this.

Ken,

That drawing is for the low-cost field for teams to practice on and in this case does not accurately portray the official field due to different material (1-1/2" steel tubing vs 4x4) .

[T3_1565]

we are definatly looking at this option. It was brought up by a couple of students day one as a way to hang. I'm sure the GDC built the tower strong enough to support it. It says the tower was built to support many robots. and I shall trust that.

Also... could you imagine the reaction if a robot broke the tower????

[edison]

hi can someone tell me how to post a message in the forum please

[edison]

i can only relply to other peoples, can't figure out how to post a new thread, where to go after i sign in??? thanks

[coldfusion1279]

Listen, I am going to assume the GDC thought of teams hanging from the vertical poles.

And they are steel bars affixed at both ends. Maybe if there were 3 robots (~500 lbs) hanging 6 feet directly out from the tower, the thing may bend, but (I don't think) brittle fracture would occur. But if you have 2 robots hanging off your robot in that orientation, your robot's arm will bend way before the steel support (unless your arm is a firmly planted pole of equal size).

If we know the phase, thickness, and modulus, we can calculate yield stress and whether the bar will fail catastrophically. Maybe the K1c value too ...

Coolness factor outweighs riskiness IMO.

[coldfusion1279]

Edison go to the forums in the orange bar at the left top of the screen. Pick a topic and at the top of the screen it will say "new thread" or something like that. Also I would pm (private message) you but I am afraid you wouldn't know how to read it. PM's are in your user cp and you can message anyone on the forum privately. There are rules etc. that you should read before posting