Gas Shock Legality?

[Bill Taylor]

In the manual, <R72-I>, seems to allow for the use of gas shocks so long as they are safe. This implies that they are legal for this game. But, <R01> restricts the methods of stored energy and does not mention gas shocks specifically. Our strategy depends on compressing gas shocks prior to match start; holding that energy throughout gameplay and releasing that energy by a motorized latch system to lift a considerable section of our robot during the Finale. Is it legal to store energy as a compressed gas shock (or multiple shocks) for use later in in the end-game?

[Josh Drake]

Without a lot of years of experience, I would say yes, because it has been allowed in the past.

[Tom Line]

You will need to ask the Q&A for an official answer, but if I were laying odds I'd say you've got a 90% chance of being legal. Gas shocks are no different than any other spring or elastic system, and there's never (that I'm aware of) been a prohibition on using those.

[Andrew Schreiber]

Short answer, as far as I can tell the answer is yes. Unless you can find a rule that explicitly forbids them they are legal. I believe they would fall under the same category as springs. (In cases where I need force and not velocity I prefer gas shocks for safety reasons) This is my interpretation and I would really appreciate if someone with more FRC experience (preferably on the inspector side of things) would confirm this interpretation.

Without a lot of years of experience, I would say yes, because it has been allowed in the past.

I happen to agree with you based on my reading of the 2010 rules but have to argue with how you came to this decision. Past years rules have no bearing this year.

[Daniel_LaFleur]

Short answer, as far as I can tell the answer is yes. Unless you can find a rule that explicitly forbids them they are legal. I believe they would fall under the same category as springs. (In cases where I need force and not velocity I prefer gas shocks for safety reasons) This is my interpretation and I would really appreciate if someone with more FRC experience (preferably on the inspector side of things) would confirm this interpretation.



I happen to agree with you based on my reading of the 2010 rules but have to argue with how you came to this decision. Past years rules have no bearing this year.

<R01> Energy used by FRC ROBOTS, (i.e., stored at the start of a MATCH), shall come only from the following sources:
A. Electrical energy derived from the onboard 12V battery (see Rule <R40> for specifications and further details).
B. Compressed air stored in the pneumatic system, stored at a maximum pressure of 120 PSI in no more than four Clippard Instruments tanks. Extraneous lengths of pneumatic tubing shall not be used to increase the storage capacity of the air storage system.
C. A change in the altitude of the ROBOT center of gravity.
D. Storage achieved by deformation of ROBOT parts.

Gas shocks are legal, but the letter of the rule <R1> does not allow them to store energy at the start of the match. Bill is correct in questioning this.

Bill, I would Q&A this if I were you. Asking if they are specifically not allowing energy to be stored in gas shocks

[Mike Betts]

In the manual, <R72-I>, seems to allow for the use of gas shocks so long as they are safe. This implies that they are legal for this game. But, <R01> restricts the methods of stored energy and does not mention gas shocks specifically. Our strategy depends on compressing gas shocks prior to match start; holding that energy throughout gameplay and releasing that energy by a motorized latch system to lift a considerable section of our robot during the Finale. Is it legal to store energy as a compressed gas shock (or multiple shocks) for use later in in the end-game?

Bill,

The GDC has posted multiple threads that verify that gas shocks can be used. Just be aware that lifting a "considerable section" of your robot implies a considerable stored energy and will attract considerable attention from the inspectors in regards to safety.

In particular, please insure that you have solid engineering data that the shocks are being used within their specifications and that you have an absolutely fail safe method of insuring the safety of all in the pits, at inspection and going onto and off of the field.

Regards,

Mike

[Karibou]

Gas shocks are legal, but the letter of the rule <R1> does not allow them to store energy at the start of the match. Bill is correct in questioning this.


So would that mean that using a spring to store energy at the beginning of the match is illegal too? I would think that bending/expanding/etc a spring (or in this case, using a gas shock) of any kind would qualify as "deforming a ROBOT part."


Definitely hit up the Q&A with the question, though.

[thefro526]

So would that mean that using a spring to store energy at the beginning of the match is illegal too? I would think that bending/expanding/etc a spring (or in this case, using a gas shock) of any kind would qualify as "deforming a ROBOT part."


Definitely hit up the Q&A with the question, though.

I would agree with this too.

Can someone please bring this up in the Q&A system or point me towards an answer already posted in Q&A? We're planning on using a gas strut on our machine this year and it would be compressed (Storing Energy) at the beginning of a match...

[Mike Betts]

Gas shocks are legal, but the letter of the rule <R1> does not allow them to store energy at the start of the match.

Daniel,

<R01> does explicitly permit the deformation of robot parts (part D).

See also Team Update #7 further addresses this...

Regards.

Mike

[Alan Anderson]

I would think that bending/expanding/etc a spring (or in this case, using a gas shock) of any kind would qualify as "deforming a ROBOT part."

I can't quite convince myself that compressing a gas is a close enough equivalent to deforming a solid for <R01> to permit it as a pre-match source of stored energy. This one will definitely need an official ruling before everyone can agree on its legality.

[thefro526]

http://forums.usfirst.org/showthread.php?t=1527

Thank you, but the above posting and answer are from 2007.

I would like to think that the ruling would be made with the same logic this year but I can't be sure... I guess we'll move forward until we hear otherwise.

[Daniel_LaFleur]

So would that mean that using a spring to store energy at the beginning of the match is illegal too? I would think that bending/expanding/etc a spring (or in this case, using a gas shock) of any kind would qualify as "deforming a ROBOT part."


Definitely hit up the Q&A with the question, though.

Springs are a deformed part and thus are allowed under <R01-D>

Daniel,

<R01> does explicitly permit the deformation of robot parts (part D).

See also Team Update #7 further addresses this...

Regards.

Mike

Compressed gasses are not deformed parts, if they were then we would not need pneumatic rules.

<R01> does not specifically allow compressed gasses (other than the pneumatic system) to be used as stored energy.

Personally, I see no issue with using it as long as it was legal and safe.

Mike, If you believe that compressed gas shocks are allowed to store energy at the beginning of a match, please show me the exact rule. TU#7 does not directly address compressed gasses at all, just the safety of stored energy.

[Andrew Schreiber]

http://forums.usfirst.org/showthread.php?t=1527

Mike, I want to accept that but that was from 2007. Definitely get a Q&A ruling on this one guys.

[Mike Betts]

Mike, I want to accept that but that was from 2007. Definitely get a Q&A ruling on this one guys.
Andrew,

You are correct. I am multitasking and did not notice the date...

Mike

[Mike Betts]

Mike, If you believe that compressed gas shocks are allowed to store energy at the beginning of a match, please show me the exact rule.

Daniel,

As you well know by now, <R72> part I is the only place that gas shocks are mentioned in this year's rules.

They are not prohibited either. That makes them a non-pneumatic robot part which, in my opinion, may be deformed IAW <R01> part D.

This is my opinion. I am not a member of the GDC.

I'm going to stop typing now...

Mike

[Rick TYler]

I don't mean to be pedantic, but I think you are discussing gas-filled springs or struts, not shocks. Shock absorbers rely on springs to support the mechanism to which they are attached, and the gas charging reduces foaming of the hydraulic fluid. Gas springs or struts rely on compressed gas to provide force, as in the struts that help support the weight of a hatchback on a car. Even if the GDC allows "gas shocks" that really isn't the same thing as a gas spring.

[Al Skierkiewicz]

I think that Daniel has the true answer here. Although gas shocks can be used on the robot, they are not specifically called out as allowed stored energy at the beginning of the match. This is a job for the GDC.

[Aren_Hill]

for "deformation of robot parts" can the gas in the shock not be deemed a part?
that is being deformed from one state to the other storing energy.

Works the same as any mechanical spring i know of

[Wayne Doenges]

FWIW, Our Rack n Roll robot used two gas struts, in compression, and two pneumatic cylinders at the start of the match. They weren't released until just before the final buzzer went off. It was called the buzzer lift. We were able to lift 500 pounds :D

[martin417]

I know that I am going to open a can of worms here, but I like worms.

Most of the discussion here so far has concerned stored energy. From a stored energy perspective, a gas strut is no different than a spring. They differ only in the manner of energy storage. So if a spring is legal, then, from, a stored energy perspective, a gas strut is legal. There could be arguments about where the initial energy to deform the spring/strut comes from in either case.

The real question about legality is brought up by this Q& response (http://forums.usfirst.org/showthread.php?t=13812&highlight=shock).

While I will stop short of saying they don't exist, I have yet to see or hear of a gas strut that is not, at least partially, filled with oil. The familiar gas strut, is simply an oil filled damper (or shock absorber), pre-charged with nitrogen at about 1500 PSI.

While not a formal authority, a description from McMaster Carr (http://www.mcmaster.com/#about-gas-struts/=5ssrr6) might help:

Note: All gas springs contain pressurized nitrogen gas as well as hydraulic fluid that lubricates the seal and provides slam-resistant damping at the end of the stroke. To avoid loss of force, you should store and install gas springs rod-end down.

[martin417]

In order to get clarification on the rules, I have asked our team contact to post this question on the Q&A"

"According to <R72> I: For the purposes of the FIRST competition, closed-loop COTS pneumatic (gas) shocks are not considered pneumatic devices, and are not subject to the pneumatic rules (although they must still satisfy all other appropriate rules). Gas shocks (struts, springs, dampers etc) are not considered pneumatic devices.

This rule would seem to imply that they are legal for FIRST use.

However, this Q&A answer :

http://forums.usfirst.org/showthread.php?t=13812&highlight=shock

Would eliminate any shock or strut that contains oil.

To the best of my knowledge, there is no gas strut or spring available that does not contain oil.

This Q&A answer refers only to <R72>I, so would seem to be implying that the GDC approves the use of these devices.

http://forums.usfirst.org/showthread.php?t=13986&highlight=shock


Can you please clarify weather gas springs will be allowed, even though they contain oil, or they are not legal for use unless it can be proven they contain no oil."

[Al Skierkiewicz]

Martin,
It would seem that the GDC answered that question here, http://forums.usfirst.org/showthread.php?t=3168&highlight=shock.

"Gas shocks (compressible gas springs) are permitted under Rule <R46>. Models of the shocks that contain small amounts of hydraulic fluid that is used as a lubricant, and which are completely sealed to prevent any escape of the fluid (and therefore not violate Rule <R36>), are acceptable. Hydraulic springs which utilize hydraulic fluid as the major damping fluid, and are therefore not really "pneumatic shocks," are not permitted. "

[GaryVoshol]

While that Q&A is from 2007, the principle probably still applies. Someone would have to ask again this year, though.

[Daniel_LaFleur]

While that Q&A is from 2007, the principle probably still applies. Someone would have to ask again this year, though.

Agreed. Until the GDC decides if gas shocks/springs can be used with energy stored at the beginning of the match, we'll have to assume it's not legal.

[martin417]

While that Q&A is from 2007, the principle probably still applies. Someone would have to ask again this year, though.

Thanks for pointing out the date, for a minute there I though I had missed a Q&A response (unthinkable).

So the question has been answered in the past (before my time, I'm a newbie). Why would it not be addressed in the present? I am not the newest FIRSTer around, are we expected to comb through all the previous Q&A answers from the beginning? I have been warned by many that previous year's rules do not apply, what about previous year's Q&A? Once a discrepancy has been made clear in the past, shouldn't it be addressed as in every year's rulebook after?

[Al Skierkiewicz]

Martin,
The reason I linked to this 2007 Q&A lies in the fact that it is in the same form of the question you are asking. It was a simple find using the search function.