Opinion on Legality of Sharp Components

Our team has an internal debate as to how an inspector will view certin mechanisms. More specifically our debate is focused around the the rope climb mechanism that will need to grab the rope.

We are very aware of R06 and R07 but that does not address the hazards imposed my internal robot functions.

For example if there are sharp teeth on a 2 inch rotating drum used to intake the rope is that legal? I don’t see anything that says its not but, I also have enough experience to know that an inspector could rule it unsafe.

For example if a drum had a surface like this. Would you feel deem that acceptable and safe? http://pasteboard.co/qlbYwAl1J.png

sharp teeth, that would cut your skin if you rubbed your finger across them?

It’s been a while since I’ve been an inspector, but: If I run my hand along it and it would get cut if I pressed harder, it’s probably going to need to get filed down. Doubly so on a moving part.

As you said that is a judgement call. Autonomous robots are inherently dangerous. What I would look for something like a rope grabber is that is is sufficiently guarded so that is not likely to be grabbed by somebody handling the robot.

if it’s sharp and there is any way you could get a finger in there while it is moving, then it’s absolutely out in my book. Guarding may help (but obviously might kill the functionality in this case)

That picture appears to be a subset of one of the pictures of this product. Those are little blades so even with a guard might be out. I assume you are providing your own rope, because this will damage the field ropes.

I’d strongly suggest a different material for your gripping surface.

Well its a cheese grater so just running your finger on it not necessarily, while its rotating or if you pushed hard most likely.

My question is how is this different from a sprocket and chain? If I push hard or put my finger in there while moving? I am not sure I see the difference. A lot of things on robots can hurt and cut if that’s the intention.

That said I am looking for opinions so I do appreciate the view point. Cant ask honest opinions and then debate them away.


Q&A 298 appears to apply here.

Since [I04] implies that team-supplied ropes are included in the official definition of ROPE, [G15-H] may mean teams may not damage their own ropes.

Here is my Q&A question on that relationship. In hindsight it could have been better-worded, but I’d already spent a day trying to figure out how to say it in order to prevent the “the LRI will judge it…” response. It effectively calls into question what the difference between damage and wear & tear is for ropes - which applies in any climber using an abrasive design for capture. It came up for us, so I had to ask.

Inspectors have the tough job of trying to determine the risk - both the chance of something happening, and the consequences if it does. Chains and sprockets are one area that can be dangerous, and many times teams will be asked to guard them to lessen the risk of an incident. Adding a guard to a chain and sprocket can, in many cases, practically eliminate any real risk of accidentally getting a finger stuck in there. Adding a guard to this, on the other hand, would probably end up removing it’s usability, as I’m guessing it would have to be exposed in order to function.

When we look for sharp edges, it isn’t just a cursory glance. We look for edges that could cause damage in the areas where team members are likely to put their hands - near the main breaker, under the robot where they pick it up from, access areas to mechanisms, etc. We also look for pinch points in areas where hands are likely to be.

To me, a rotating cheese grater on a robot just sounds dangerous. We’ve all seen times in the pits where people jump back because they weren’t expecting the robot to move, or where a robot jumps off it’s blocks and starts driving away before someone can hit the spacebar to stop it. Accidents happen, and I, for one, wouldn’t want an item like this to turn into an accident for one of my students. I’m sure you guys can find a better way to climb over the next couple of weeks if you put your minds to it!

I’ve been advocating for our team to have some kind of lock-out to keep the winch with robe grabbing tines from moving, unless specifically being used for testing.

Regardless of how legal it ends up being or what solution you end up going with, I would definitely suggest some kind of guard to place on this kind of mechanism as a “remove before flight” sort of thing - say a piece of lexan held on with Velcro you pull off as you’re leaving the field. It couldn’t hurt with arguments you may find yourself in as to the safety of your mechanism, at the very least.

I did see the Q&A. It seems like most are in agreement. Its not outright illegal but not the best idea. Like I said we were debating this and came to the same conclusion. We have other ideas and designs. Thanks for the feeds back from all. Its good to get a general consensus to know where you stand.