Position of Eye Bolt

[Garten Haeska]

Make sure it's toward the center of gravity.

[jake517]

thanks!

[EricH]

Originally Posted by Garten Haeska

Make sure it's toward the center of gravity.

Either an eyebolt or an open spot to wrap rope around needs to be near the balance point (which is one method for finding CG), placed in such a way that it is easily accessible after the robot has climbed. See R10.

[Oldbikerider]

Originally Posted by Garten Haeska

Make sure it's toward the center of gravity.

And above it!

[Anupam Goli]

Originally Posted by Oldbikerider

And above it!

It would be very inconvenient for the belaying points to be under the robot

[Cal578]

I agree that the eyebolts should be above the center of gravity, which leads to the question of orientation. We're concerned about how inspectors will interpret this.

R10
Teams must supply at least two (2) attachment points for the belaying device (see Section 2.2.5) to mount to their ROBOTS. Attachment points must be:
A. easily accessible after the ROBOT has CLIMBED the PYRAMID,
B. on opposite sides of the ROBOT,
C. located near the ROBOT’S balance point, and
D. made from exposed structural members that will allow a rope to be wrapped around it or two eyelets (McMaster PN3014T45 or similar) mounted to the frame. Opening of the eyelets must be at least ¾ in. in diameter.

(emphasis mine)

Our robot climbs the outside of the pyramid corner on its belly. We put the eyebolts near the front corners of the chassis, so that if the robot were to slip and be supported by the belay ropes, it would pretty much stay safely in place.

One interpretation of "near the balance point" might lead us to put the bolts on the sides around the geometric center of the robot. In that case, if the robot were to slip, it would suddenly try to level itself. It would swing down, past level, and oscillate until something dampens the oscillation. That something might be a body part near that height, such as a head.

So, I think we're following a safer interpretation of the rule. Do you think inspectors will see it that way?

[Alan Anderson]

Originally Posted by Cal578

Our robot climbs the outside of the pyramid corner on its belly. We put the eyebolts near the front corners of the chassis, so that if the robot were to slip and be supported by the belay ropes, it would pretty much stay safely in place.

One interpretation of "near the balance point" might lead us to put the bolts on the sides around the geometric center of the robot. In that case, if the robot were to slip, it would suddenly try to level itself. It would swing down, past level, and oscillate until something dampens the oscillation. That something might be a body part near that height, such as a head.

So, I think we're following a safer interpretation of the rule. Do you think inspectors will see it that way?

Are you intending for your drive team to pull the robot from the pyramid and lower it to the floor in its "tilted" orientation before removing the belay ropes? I would expect the inspectors to assume the robot will be removed and set on the floor by two people holding it in an approximately horizontal orientation.

[Cal578]

The robot latches onto the top rungs, using hooks near the front of the robot. So, it must be lifted 1-2" in its tilted orientation, and pulled away from the pyramid that way. We have found that it's easiest to keep it tilted that way as it is lowered, usually setting the rear bumper on the floor first, then setting the front down. This is the least strain on the lifters' backs (makes it easy to bend knees instead of waist & back), safest for people and robot.

[Jon Stratis]

Originally Posted by Cal578

I agree that the eyebolts should be above the center of gravity, which leads to the question of orientation. We're concerned about how inspectors will interpret this.

(emphasis mine)

Our robot climbs the outside of the pyramid corner on its belly. We put the eyebolts near the front corners of the chassis, so that if the robot were to slip and be supported by the belay ropes, it would pretty much stay safely in place.

One interpretation of "near the balance point" might lead us to put the bolts on the sides around the geometric center of the robot. In that case, if the robot were to slip, it would suddenly try to level itself. It would swing down, past level, and oscillate until something dampens the oscillation. That something might be a body part near that height, such as a head.

So, I think we're following a safer interpretation of the rule. Do you think inspectors will see it that way?

I won't be inspecting at your regional, but I think all the inspectors are on the same page - the belay points are there for safety, and should be placed on the robot in a way that makes the robot safe to lower.

That said, you may be questioned as inspectors will be looking for them to be near the center of gravity, and will be inspecting it while it's sitting on the floor. If you explain how its safer and demonstrate the robot removal process for them (at the practice field?), I would personally be surprised if you were forced to change the belay points to some place that makes the robot less stable (and thus less safe) while lowering it. Of course, this is all based on your description, without having seen the robot, how it climbs, or how you remove it from the pyramid. Actually seeing the process is what would form my decision.

[Cal578]

Thanks, Jon. That's really helpful, and encouraging.

Any comment on using rope as an attachment point, as someone else posted above?

[Jon Stratis]

Being an Eagle Scout and having done some rock climbing and rappelling, I can say that rope is only as strong as the knot that holds it together. A rope rated to 1600 lbs instantly gets a rating of 0 lbs if the knot pulls out.

That said, I would refer to R10, part D:

R10

Teams must supply at least two (2) attachment points for the belaying device (see Section 2.2.5) to mount to their ROBOTS. Attachment points must be:

A easily accessible after the ROBOT has CLIMBED the PYRAMID,
B on opposite sides of the ROBOT,
C located near the ROBOT’S balance point, and
D made from exposed structural members that will allow a rope to be wrapped around it or two eyelets (McMaster PN3014T45 or similar) mounted to the frame. Opening of the eyelets must be at least ¾ in. in diameter.

I wouldn't consider rope to be structural or similar to the referenced McMaster eyelet.

[Anupam Goli]

Originally Posted by Cal578

Thanks, Jon. That's really helpful, and encouraging.

Any comment on using rope as an attachment point, as someone else posted above?

I'm not sure how much an eyebolt weighs (shouldn't be much), but our team is using these:

http://www.mcmaster.com/#standard-pull-handles/=ljt85e

light, cheap, and make great belaying points AND lifting handles for the robot.