belaying device
 

im unsure if this has been asked before but how much space will a team need to save on their robot for the belaying device trying to figure this out so we don't acidently use that space :)

Re: belaying device
 

You're just supposed to mount a couple of eyebolts close to the robot's point of balance and on a structural part of the robot. Just make sure that you can hang the robot from them and balance it well, and you should be fine.

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k thanks for information

Re: belaying device
 

Theoretically, none... you just need to be able to wrap a rope around it and it needs to be near the Center of Gravity. Doesn't even need to be eyelets or anything fancy, it could just be some holes in your frame at the right place. As long as it's accessible and easy to attach a rope to, etc..


http://frc-manual.usfirst.org/viewItem/279

Re: belaying device
 

Has anyone considered this:

A robot that is, say, 45" tall. With the main frame/chassis in the bumper zone, so no more than 10" from the bottom. Means at least 35" (and possibly a lot of weight) above the chassis level. Two belay attachments on the frame, at the chassis level.

Attach belay device to attachment points. Team is lifting robot off of pyramid. Something goes awry and team loses grip or whatever (this is why there is the belay device, right? In case someone drops the robot, to keep it from falling on someone's head.). Robot does not fall, but it FLIPS OVER due to top being heavier than bottom, whacking a student or two in the noggin. Ow!

Our lead mentor believes this is not safe, and that they should have required three belay attachments.

He told us about a similar accident that occurred, involving a 100-ton (I think that is what he said, it was REALLY heavy) motor or transmission or engine or something, of which he was aware. He is VERY concerned about an accident of this kind occurring with a robot in a competition, with bad results (albeit not as bad as the one involving the 100-ton engine).

I'm throwing this out there, at his request (he's too busy working on the robot to be on CD), to see what others think. I might not have expressed it properly, I hope you can figure out what I'm talking about.

Re: belaying device
 

If the two attaching points are above the CG, then it should be stable. Make sure they are above the CG. This is a good point you made...since the example robot in the game manual does not have anything above the chassis, the belay points are on the chassis. On a real robot, they should be higher. The example robot is a lousy example of where to place the lifting points.

Re: belaying device
 

The exact location is only important from a safety stand point if you are doing a level 3 climb. For most of the teams they will be on the robot to satisfy the rules. While the field people might require them to be used for a lower level climb, the CG of the robot will lower.

The only people close enough to get hit with the robot should be the ones actively taking the robot off the tower. They should be situationally aware enough not to get hurt if things do not go as planned. I appreciate your mentor's concern, but there is a lot difference between a primary lift point for a 100 ton motor & a controlled fall device for a 150 lb robot.

Re: belaying device
 

It was unclear to me what "near the robot's balance point" meant - whether it was just near the balance point front-to-rear, or also near the balance point top-to-bottom. I suspect most teams will place their hooks or attachment points. on the frame of the robot, close to the ground, but near the "balance point" front-to-rear. If you have a sturdy frame up higher on the robot, you can use that, but many robots seem to have their study frame components low down with just fancy apparatus (shooters, climbing mechanisms, sensors, extendable arms, etc.) up higher.

Sure, if the robot doesn't climb high, it's not an issue. I'm talking about the hooks/attachment points that are actually used, not those on there 'just for show' on robots that don't climb high.

Re: belaying device
 

Cynthia,
The "balance point" is specifically referring to the situation outlined above. The belay device is used the same way a belay is used in rock climbing. It is meant to stop a fall, not to be used to lower the robot. If the belay devices are attached below the center of gravity, and the team loses control, the belay device will hold the robot but the robot may pivot about connection point. If the belay devices are above but near the pivot point, the robot will simply be stopped by the field people and the team can then continue lowering the robot.

Re: belaying device
 

The rule says "at least two" belay points. We have eyebolts at each of the four corners of our robot. Will that be okay? Due to the wording, we were working under the assumption that each belay would have multiple carabiners.
I suppoe we could just attach at two opposing corners and that would be balanced, too.

Re: belaying device
 

Taylor,
There will be only two carabiners as I remember. That is why the rule stated near the balance point.

Re: belaying device
 

I don't think that in the corners would satisfy part C of the belay rules.

Al, you remember correctly. The belay system has two carabiners for you to use that trail back to a single line that will be belayed from the far side of the pyramid.

Wetzel

Re: belaying device
 

Here's an example from the twitter feed that John Boucher posted on CD.
Team members are lowering the weight of the robot. The belayer is only providing a stop against a sudden drop.
The belay is physically incapable of lifting the robot, providing upward force. For that you'd need a block & tackle.

Re: belaying device
 

We discussed the difficulty in lowering our robot at length yesterday. Our robot is really tall and a level 3 climber. We set up a belay system with 80 pounds of weight at the height our robot would be and none of our prospective drivers could keep it up without putting weight on the belay line. If the robot falls and pivots there is wide radius where people could get hurt. I'm really curious about how this is going to work out with all the chaos on the field. Happy to not be in a week one competition this year.

Re: belaying device
 

Tell your drivers to hit the gym. 80 pounds of weight split between two people is only 40 pounds each. You have at least three weeks before competition, you can see real gains in strength in that time, and if you are a mid to late competition, you could have more than two months for strength training.

If your drivers can't safely take the robot down, you will likely get a yellow card, especially if you have trouble every time you go out there. You don't want a yellow card.

Wetzel