Flat Hose

[neurotrek]

Our team would like to know if it would be against the rules to use a flat hose as an air bladder for our lifting mechanism.

Thanks.

[EricH]

It would be a pneumatic component. It would also not be one of the specifically allowed items in <R72>. Therefore, it would be illegal under <R71>.

[neurotrek]

What makes this considered to be a pneumatic component?

[EricH]

Pressurized air. At least, if you're using it to hold air, or cause movement with air, it's pneumatic.

[neurotrek]

Thank You.

[rsisk]

Thanks Eric,

I'd like to ask a follow up question.

What if the hose and connectors were rated at 125 psi, and it was a COTS item, generally available to other teams.

Are there other characteristics that would make it illegal?

[EricH]

Given that it was COTS rated to 125 PSI, I'd look at the following Q&A:

http://forums.usfirst.org/showthread.php?t=13703
http://forums.usfirst.org/showthread.php?t=14242 << Especially this one...

If you can't answer it that way, ask it to Q&A and see what they think.

[rsisk]

Not sure either of those help me, or maybe it is my ability to read the rules, I don't know. Could be the six week zombie syndrom

Anyway, if the hose is considered a pneumatic cylinder, then why is it not permitted under <R72>D

In addition to the pneumatic cylinders provided in the KOP and the “free” pneumatic
cylinders available for order through the Free Pneumatic Components Order Form,
additional air cylinders or rotary actuators may be used. Cylinders may be of any
configuration, and may be of any size up to a maximum of 24-inch stroke and 2-inch
diameter.

If the hose is considered a storage cylinder then it is excluded under <R72>A:

One or two additional Clippard air storage tanks (Clippard Part Number AVT-32-16),
equivalent to those provided in the kit. This means that up to four, and no more, Clippard air
storage tanks can be used on the ROBOT.

I will submit to the GDC Q&A once I figure out if I can get the hose I need. Thanks for your input

[EricH]

The second one refers to a diaphragm, or flexible membrane, to convert air force into mechanical force. I think this the type of device that you're asking about. The GDC has specifically pointed to that as not legal.

There was one--in fact, the first one in the pneumatics--about using inflatable items. However, it doesn't cover inflatables that are inflated using the compressor's air.

http://forums.usfirst.org/showthread.php?t=13703

You might reference it when you ask, something to the effect of, "Regarding [previous link], does the answer change if the inflatable item is COTS, pressure rated to at least 125 PSI, and inflated using the onboard FRC pneumatics system? If not, which rule does it violate?"

[Al Skierkiewicz]

Richard,
The two Q&A answers do cover your question. The GDC's response is related to devices that produce movement. The hose expansion produces movement by the introduction of air pressure. The only devices that may do that are defined in R72 as cylinders up to a specific size and rotary actuators.

The last paragraph of section 8.3 gives you a little statement from the GDC that might help.

"In addition, another intent of these rules is to have all energy sources and active actuation systems on the ROBOT (e.g. batteries, compressors, motors, servos, cylinders, and their controllers) drawn from a well-defined set of options. This is to ensure that all teams have access to the same actuation resources, and to ensure that the inspectors are able to accurately assess the legality of a given part."

[rsisk]

I see that the explanation of what we are intending to do is not clear.

We are thinking of putting a hook on the end of a flexible tube/hose that is deflated. We would inflate the hose with air from the accumulator(s) which would raise the hook to the point we could grab the bar. Then we would use a winch to lift the robot, probably deflating the tube once the hook is on the bar.

So there is no piston in the hose.

I'm still unclear whether the hose would be considered a cylinder or accumulator. It's intended use is closer to that of a cylinder.

Based on Al's last comment about the last para. of 8.3 it looks like the intent of the rules is to have a well-defined set of energy sources/actuation systems would probably exclude what we are thinking of doing, but...

...once we get specifics on the hose and fittings, I'll submit the question to the GDC for a final ruling.

[EricH]

Someone wanted to do the same thing with PVC. GDC said no. http://forums.usfirst.org/showthread.php?t=14194

[artdutra04]

Originally Posted by rsisk

I see that the explanation of what we are intending to do is not clear.

We are thinking of putting a hook on the end of a flexible tube/hose that is deflated. We would inflate the hose with air from the accumulator(s) which would raise the hook to the point we could grab the bar. Then we would use a winch to lift the robot, probably deflating the tube once the hook is on the bar.

So there is no piston in the hose.

I'm still unclear whether the hose would be considered a cylinder or accumulator. It's intended use is closer to that of a cylinder.

Based on Al's last comment about the last para. of 8.3 it looks like the intent of the rules is to have a well-defined set of energy sources/actuation systems would probably exclude what we are thinking of doing, but...

...once we get specifics on the hose and fittings, I'll submit the question to the GDC for a final ruling.

Would coiling up a thin (like 1/16" or 3/32") strip of polycarbonate with the hook at the end and a servo/pneumatic release pin work?