safety of ATV whip

[mfcarr]

We are a rookie team considering using a fiberglass ATV flag whip that will be curled in a circle, with considerable potential energy, and then released in the final period to get a hook up to the top of the tower. The manual warns against this, indicating that the inspectors could disqualify a robot if they feel the device is not safe. We have thought of making a track that would guide the tip of the ATV whip so that it is only free when it is pointing almost straight up. Another idea was releasing the tip of the whip by spooling out a string attached to a motor. What characteristics of the lock-release mechanism for the tip of the whip and other safety features do we need to incorporate? Should we abandon this design?

[,4lex S.]

Unless you slow it down or control it somehow, the safety inspectors will probably take notice. My main worry would be 1) What happens if any of the parts involved fail? and 2) What are the chances of it getting jostled lose during competition (going over bumps, getting into high speed collisions)?

The fact that you are questioning its safety now is a good indicator it is an unsafe idea for competition.

[EricH]

As rookies, you weren't around to watch the flags fly from 2006-2008.

The alliance identification system in those years was a red or blue flag, mounted on a roughly 3' fiberglass pole of the type you describe, put into a 1' long vertical PVC tube on the robot at a certain height. If it bent too much, it went flying. This was mitigated in 2008 when a stopper was added to the flagpole.

If you're worried about safety, your concerns are probably valid.

Your best bet in this case, if you did use it, would be to use the motor reeling out cable that is attached to the hook, which would be securely attached to the pole (or attach a cable to the the hook and another to the pole, and reel them both out). Then you winch the cable back in to climb up. If you go another route, look through CD-Media for examples of the 2004 hangers.

[Meredith Novak]

I thought I was so clever when I bought one of these ATV flags at the farm store. It seemed like a good idea until it shattered and we had several fiberglass shard splinters.

[JHSmentor]

Well - seems that the ATV whip is out.

But, there are many types (or grades?) of composite rod that might work for this application. Fiberglass or aluminum tent poles, or fishing rods (not the little flimsy ones) that can practically bend in half.

Has anyone tried anything like that? It's something we may look into more - but if someone else already has then that would be very helpful.

[Daniel_LaFleur]

Originally Posted by JHSmentor

Well - seems that the ATV whip is out.

But, there are many types (or grades?) of composite rod that might work for this application. Fiberglass or aluminum tent poles, or fishing rods (not the little flimsy ones) that can practically bend in half.

Has anyone tried anything like that? It's something we may look into more - but if someone else already has then that would be very helpful.

I wouldn't say "it's out", but I would make sure there is plenty of safety margin and that you have that safety margin documented for the inspectors. I'd also make sure that the locking system that holds it in place is VERY robust.

[JHSmentor]

Originally Posted by Daniel_LaFleur

I wouldn't say "it's out", but I would make sure there is plenty of safety margin and that you have that safety margin documented for the inspectors. I'd also make sure that the locking system that holds it in place is VERY robust.

Agreed!!

I looked into using fishing rods but they are not flexible enough and will definitely break.

Tent poles may work but the larger diameter ones that I found were not flexible enough either. Smaller diameter ones may work but may not be strong enough or durable. So, at this point, I'm not convinced this is a viable option.

[Bill_B]

So it appears that ATVs are unsafe for more than one reason.

If you are using this to lift an attachment hook off the back/top of your robot, you should consider a much easier and more reliable method. Take a look at your retractable tape measures and figure out why they can be extended as far as they do without "wilting." If you are looking for another example, look up the Mars Viking lander digging mechanism. Now there was a robot!