Reasoning of the GDC

[EricVanWyk]

I'm actually a fan of the 0.32CV rule, and I forgive it for appearing to be petty and random at first blush. It reduces cost to teams for free, so I hope we see similar changes in the future.

In the past, we were only allowed to use specific part numbers for valves. Now we can use any valve we have... that isn't better than those specific part numbers. Combined with the 24V ruling, it allows teams to use many valves that weren't available last year, thereby reducing probable cost. Even though your particular valves aren't available, many teams have been able to tap into existing unused resources.

Your complaint is that it doesn't go further, and I agree with you in principle - not enough to complain this year. 0.32CV is low hanging fruit, because we've proved it out over the last however many years and increasing the flow rate could arguably require testing/validation/etc. I'd rather the GDC pick as much low hanging fruit as possible before moving up the tree.

That said, I do hope it opens further next year.

[martin417]

Originally Posted by EricVanWyk

I'm actually a fan of the 0.32CV rule, and I forgive it for appearing to be petty and random at first blush. It reduces cost to teams for free, so I hope we see similar changes in the future.

In the past, we were only allowed to use specific part numbers for valves. Now we can use any valve we have... that isn't better than those specific part numbers. Combined with the 24V ruling, it allows teams to use many valves that weren't available last year, thereby reducing probable cost. Even though your particular valves aren't available, many teams have been able to tap into existing unused resources.

Your complaint is that it doesn't go further, and I agree with you in principle - not enough to complain this year. 0.32CV is low hanging fruit, because we've proved it out over the last however many years and increasing the flow rate could arguably require testing/validation/etc. I'd rather the GDC pick as much low hanging fruit as possible before moving up the tree.

That said, I do hope it opens further next year.

I just looked up last years rules, and saw that the .32 Cv rule came in then. (we didn't use pneumatics last year), but in 2008, there was no restriction on valves. We have a quantity of valves from 2008, they meet all rules, but Cv=~.4 Now we have to buy more valves, and at $50-$75 each, that is not a cost reduction. Teams already had access to the pool of valves you point out.

Limiting the Cv, but not limiting the number of valves allowed (It is allowed to hook up as many valves as you wish to a single actuator, this has been answered in Q&A) only punishes teams that can't afford a lot of valves, and those teams that have access to valves that would otherwise be legal.

The smaller Cv doesn't hurt us, but the $$$ we now have to spend to get legal valves does.

[EricVanWyk]

Originally Posted by martin417

I just looked up last years rules, and saw that the .32 Cv rule came in then. (we didn't use pneumatics last year), but in 2008, there was no restriction on valves. We have a quantity of valves from 2008, they meet all rules, but Cv=~.4 Now we have to buy more valves, and at $50-$75 each, that is not a cost reduction. Teams already had access to the pool of valves you point out.

Limiting the Cv, but not limiting the number of valves allowed (It is allowed to hook up as many valves as you wish to a single actuator, this has been answered in Q&A) only punishes teams that can't afford a lot of valves, and those teams that have access to valves that would otherwise be legal.

The smaller Cv doesn't hurt us, but the $$$ we now have to spend to get legal valves does.

My apologies and retraction. I must have skipped a few years with pneumatics rules. My sporadic view supported my claims, but it appears that a full view does not.

[Jones571]

Originally Posted by martin417

I just looked up last years rules, and saw that the .32 Cv rule came in then. (we didn't use pneumatics last year), but in 2008, there was no restriction on valves. We have a quantity of valves from 2008, they meet all rules, but Cv=~.4 Now we have to buy more valves, and at $50-$75 each, that is not a cost reduction. Teams already had access to the pool of valves you point out.

Limiting the Cv, but not limiting the number of valves allowed (It is allowed to hook up as many valves as you wish to a single actuator, this has been answered in Q&A) only punishes teams that can't afford a lot of valves, and those teams that have access to valves that would otherwise be legal.

The smaller Cv doesn't hurt us, but the $$$ we now have to spend to get legal valves does.

in 08 they did not limit cV but only limited you to the ones provided in the current KOP or previous years.

Originally Posted by 2008Manual

Prior year FIRST Kit Of Parts solenoid valves, and pneumatic tubing may be used in addition to those provided in the 2008 Kit Of Parts. Their costs must be accounted for as explained in Section 8.3.3 Budget Constraints.

As we have found the old festo block has a Cv of .3 so it is good. So are you saying the SMC valve of 2008 had a .4 Cv? and if so were did you get this information from.

[martin417]

Originally Posted by Jones571

in 08 they did not limit cV but only limited you to the ones provided in the current KOP or previous years.

As we have found the old festo block has a Cv of .3 so it is good. So are you saying the SMC valve of 2008 had a .4 Cv? and if so were did you get this information from.

Don't make a statement unless you are sure of your facts. I always check my facts before I post.

from the 2008 rule book:

<R88> There is no limit to the number of solenoid valves, pressure regulators, pressure gauges,
and connecting fittings that may be used on the ROBOT. All such devices must be “off the
shelf” pneumatic devices rated by their manufacturers for pressure of at least 125psi.

We used a manifold with 4 SMC valves rated at .4 Cv.

[Jones571]

Originally Posted by martin417

Don't make a statement unless you are sure of your facts. I always check my facts before I post.

from the 2008 rule book:



We used a manifold with 4 SMC valves rated at .4 Cv.

And R87 2008 is were I took my statement of solenoids are allowed from 08 kop and older so how are my facts not checked? I read the entire pneumatics section not just the rule that if taken out of context helps me.

R87 IMHO says all solenoids needed to currently or previously offered in a KOP. R88 would clarify this even further that it must be COTS so you can't use something that would be discountinued and you can have as many as you would like on your robot.

So if the SMC you used was never in a KOP it should of never been a ROBOT PART to begin with.

[martin417]

Originally Posted by Jones571

And R87 2008 is were I took my statement of solenoids are allowed from 08 kop and older so how are my facts not checked? I read the entire pneumatics section not just the rule that if taken out of context helps me.

R87 IMHO says all solenoids needed to currently or previously offered in a KOP. R88 would clarify this even further that it must be COTS so you can't use something that would be discountinued and you can have as many as you would like on your robot.

So if the SMC you used was never in a KOP it should of never been a ROBOT PART to begin with.

Again, opinions are just that. We had the same concern in 2008, and asked and received the following on Q&A:

Pneumatic System
Pneumatic valves
Pneumatic valves
Posted by FRC1771 at 01/18/2008 09:18:14 am
Rules <R86> and <R87> seem to limit the pneumatic valves to the ones in the KOP (from this
or previous years). However, rule <R88> appears to allow any solenoid valve, regulator,
gauge, or fitting, as long as they are off the shelf, and and rated for at least 125 PSI.
My question is: can we use other valves and fittings than those supplied in the kit. Specifically,
Valves with larger Cv than the ones in the kit, and other one touch fittings such as muliti-T's
Page 172 of 223
2008 Q&A Forum Export
generated: 02/27/2008 09:27:01 am EST
etc.
Re: Pneumatic valves
Posted by GDC at 01/21/2008 12:32:44 pm
Rule <R88> specifically permits the use of additional (not-Kit Of Parts) solenoid valves and
fittings. Valves with a larger internal Cv than the KOP valves are permitted by this rule. Note,
however, that all valves and fittings must connect to, and use, 0.160" ID pneumatic tubing.
This is a safety constraint (as the Cv for the entire pneumatic system is dominated by the
tubing flow rate) and must not be violated.

[Lil' Lavery]

Wait, so you're complaining about not being able to use a part that you purchased before you knew the new games' rules (and a rule that existed in 2009 as well)? Did you complain about not being able to use traction wheels last year, as well?

[martin417]

Originally Posted by Lil' Lavery

Wait, so you're complaining about not being able to use a part that you purchased before you knew the new games' rules (and a rule that existed in 2009 as well)? Did you complain about not being able to use traction wheels last year, as well?

Perhaps people are misunderstanding the gist of this thread. I am not complaining (well, maybe a little). The title of the thread is "reasoning of the GDC" The purpose of the thread is not to complain, or to bash the GDC.

I started this thread as a discussion about the motivation and reasoning that goes into rules and decisions made by the GDC. I was using the valve rule as a case study on this subject. What could be the motivation behind limiting the Cv to .32? It is NOT flow limitation, because it is legal to use as many valves as you like, connected in parallel to create a Cv as high as you would like, provided you have the money to buy the valves. It is possible that, as AL said, rules are put in place as constraints to make teams think. I doubt that is the case here, because it doesn't take much thinking to put two valves in place of one.

So the question is, why the rule? (I realize now that the rule appeared last year, but that doesn't make any difference). One thing that lawmakers (rule makers) in general overlook is the law of unintended consequences. While there may be a perceived reason to make a change, that change may affect many things far beyond what was intended, sometimes, the negative outweighs the positive.

In this case, the restriction favors well funded teams, either by allowing them to get an advantage by using more valves, or by forcing a team to purchase new valves when they have perfectly serviceable ones in stock.(our case). This is, in my view, a negative. I don't see what he positive could be.

Again, not bashing, just putting forward thoughts for discussion. So, if you have a thought, put it out here. Discuss it civilly. Tell me what the positives of this rule might be, and how they outweigh the negatives.

[Al Skierkiewicz]

Martin,
I follow you up to a point but I have to say that there aren't that many well funded teams this year. I would think the majority are struggling as we are. Sign of the times, but I would rather teams be in and struggling than out. Of course it always possible that we feel stronger about GDC decisions this year because we are all struggling. We will know for sure when we get to regionals and find many old friends are not there.

[martin417]

Originally Posted by Al Skierkiewicz

Martin,
I follow you up to a point but I have to say that there aren't that many well funded teams this year. I would think the majority are struggling as we are. Sign of the times, but I would rather teams be in and struggling than out. Of course it always possible that we feel stronger about GDC decisions this year because we are all struggling. We will know for sure when we get to regionals and find many old friends are not there.

Al,

I agree that times are tough, and many teams are struggling with budget issues. The budget issue is another facet of the law of unintended consequences. Since this thread is about reasoning and motivation for GDC decisions, and it is a stated goal of FIRST to be as inclusive as possible, and to have as many teams in as many places as possible, I think this an excellent topic for discussion.

How do GDC rulings affect the cost of participating in FIRST? We have already discussed the valve rule and two ways it can impact costs, what other examples can we come up with? One positive example is the motor rule. All motors allowed for use are provided in the KOP (with the exception of the optional 3 CIMs this year) That keeps costs down, since teams don't have to worry about competing with other teams using expensive exotic motors.

I am assuming that members of the GDC read posts here on CD, and want this to be a thought provoking exercise that may bring up points of view they haven't explored. So when responding, please stay on the topic at hand, be polite, positive, and constructive. I don't want this thread to turn into a complaint fest.

[Al Skierkiewicz]

Martin,
Some of the indicators will be the number of robots that show up with the kit frame and wheel standoffs. Another less accurate indicator will be how many students travel to out of town events or how many second events teams are registered for. Some of the restrictions that the GDC has included in the rules tend to limit the functionality of the robots. This may be in part a method of leveling the field and part limiting the need for teams to design and build do all robots. This is the first year in a ball game that robots can't carry or possess more than one ball. That leaves teams with no ball pickup to design and pay for.

[tomgee4me]

Martin,

I just read your post and got worried. We are a rookie team that has done exactly what you cite as an example case. I just read through Update #7 and am not quite sure what you mean when you say the lower part of the frame will be in violation. Are you talking about the bolt heads that would be protruding beyond the actual frame?

Thanks for pointing this out.

Tom Gee
Mentor, Rookie Team #3323

[Rick TYler]

Originally Posted by Al Skierkiewicz

This is the first year in a ball game that robots can't carry or possess more than one ball. That leaves teams with no ball pickup to design and pay for.

I guess it's possible that the GDC made the rule to save teams money, but I think it's far more likely that we are seeing "robot soccer" in which "hands" aren't legal.

[MrForbes]

Originally Posted by martin417

In this case, the restriction favors well funded teams, either by allowing them to get an advantage by using more valves, or by forcing a team to purchase new valves when they have perfectly serviceable ones in stock.

The restriction also encourages teams to think of other ways to solve the problem. How about designing a gearbox/mechanism and using a motor to make it work, instead of buying several expensive valves?

I don't worry much about the reasoning of the GDC. I understand that the committee works in strange and mysterious ways, and accept it. The rules are what they are, and we'll work within them as best we can.