# YMTC: Redabot weighs 129.8?

You Make The Call (YMTC) is a series of situations where you can be the ref and make the call.

Redabot uses two different upper body mechanisms, Jumpy and Grabby. Jumpy is placed on Redabot when she wishes to jump on the bar and Grabby is installed when she wishes to pick up balls. Each mechanism uses one drill motor. Redabot passes inspection at 129.8 lbs with the base, Jumpy, and Grabby on the scale BUT only Grabby has a drill motor installed. Since only one mechanism is on Redabot at a time, the drill motor is swapped between Jumpy and Grabby. To save the pain of swapping out drill motors, Redabot decides to install her extra drill motor on Jumpy. Therefore, Redabot never needs to swap motors when installing Jumpy or Grabby onto the base.

Based on the 2004 Robot Rules, YOU MAKE THE CALL!

<R06> The maximum allowed weight of all robot configuration components combined is 130.0 pounds (58.97kg). At the time of weigh in, the basic robot platform and any additional items that might be used in different configurations of the robot must be weighed together. Weight limit includes (one) 12V battery,control system, decorations, bumpers, and any other attached parts.

This one is easy. For weigh in, you need to weigh it with all items that might be used. All items includes all motors.

Wetzel

<R06> The maximum allowed weight of all robot configuration components combined is 130.0 pounds (58.97 kg). At the time of weigh in, the basic robot platform and any additional items that might be used in different configurations of the robot must be weighed together. Weight limit includes (one) 12V battery, control system, decorations, bumpers, and any other attached parts.
If the second drill motor weighs more than .2 lbs, it’s illegal. The weight of the base plus all of the mechanisms will be more than 130.00 lbs. Redabot needs switch out the motor or figure out a way to drop the .2 lbs they need. (cheeseholes, anyone?)

Not so fast. It’s also a spare part, which doesn’t count against the limit.

That’s a symptom of the real problem–a badly conceived rule. There’s no universal way of determining whether their extra drill is a spare part, mounted on the mechanism for convenience (where it is legal) or a part of the mechanism (where it is illegal, due to weight). You could take the naïve approach, and say, “well, it’s attached to the mechanism, so it mustn’t be legal”, but that comes down to a silly semantic argument as to when something is part of something else, and when it’s a separate entity. Note that they (properly) pass the weigh-in, because they know that a mechanism or part need not be attached to the robot to be part of its official weight (e.g. the two function modules–which probably can’t be attached at the same time).

There is a universal way of determining whether it’s a spare part or not, I think.

<R76> The costs of “spare” parts are excluded from this rule. A spare part is defined as a part that a team has obtained as a direct replacement for a failed or defective Robot part (Kit part or non-kit part)

If the team is putting it on the other assembly for convenience and not to replace a busted drill motor, then I don’t think it counts. If it’s not a spare part, then it has to be counted on the weight.

I agree with Kevin. A spare part is for replacement only. Once you attach it to the arm or whatever it is now part of the robot. Once assembled the robot must still meet weight requirements.

We must make sure that we don’t try to make the rules meet our way of thinking. Rules should state the obvious. In this case you weigh in what you are going to use. If you add to the assembly then you must reweigh with ALL parts. I see no problem if you switch motors around between assemblies as that is how you weighed in.

As an inspector under 2004 rules, I would have ruled this robot did not make weight. Under 2003 rules it would have. I personally feel that the maximum weight a robot will be competing at is the test weight for inspection as the 2003 rule stated. After all, the max weight and size of a robot when it is on the field is the the critical issue to a level playing field, not the parts that are left behind. You don’t qualify for size with all attachments fitting in the size box, just the robot with each attachment so that no attachment is over the size limit.

I would have to say it would not pass the inspection. If it had the other drill motor installed I would say it would pass if it met the weight requirements. I think this is what FIRST was trying to avoid when saying all mechanisms must be counted in the weight. When looking at these rules we must look at the purpose of the rule rather than trying to dig in the wording to find the loophole.
-Aaron

That only addresses the reason for which it was obtained, rather than the reason for which it was installed. It is legitimate to buy it in order to cover a possible malfunction, then preemptively install it in one module or the other. That is only tantamount to changing a motor in an integral mechanism for the heck of it, rather than when broken (which isn’t a bad idea in some cases, and which is perfectly legal). The issue seems to be with the time saved, which seems like one hell of a worthless thing to be concerned about!

Just out of curiosity, Aaron, since only one drill motor is installed at inspection-time, and it meets weight limits at that time, why wouldn’t it pass the inspection? You state “I would have to say it would not pass the inspection”, but there is nothing at inspection-time that would constitute an illegal part or mechanism.

As for why I think that the rule is ill-conceived, look at it this way: if you had a quick-change collar on the Globe motor, it would make sense to make two–one for the robot and one for the spare motor. Is it being implied that such a collar is inherently illegal, unless you defeat its purpose by only waiting until you need it in order to install the collar on the motor? Also, I agree with Al’s reasoning regarding the comparable example of robot sizing.

I can definitely attest that I liked the 2003 rule better, but I don’t think that the 2004 rule even covers the situation in question.

Sure, you can install the second motor on the second module * as long as both modules and the base weigh a total of less than 130 lbs.* In this situation, Redabot would weigh more than 130 lbs, if reweighed after adding the second motor.

With what you’re saying, teams could easy add another 20 lbs to their robot by added backups for when something fails.

“Well, we’re at 128 lbs but … that battery’ll die sometime - we’d better make room for two, just in case!”

“Alright, we’re at 130 exactly. But I was thinking - that chip motor could give out. Instead of swapping the whole motor if it fails, let’s just throw another on there now so we can move the wires and save ourselves some trouble!”

No one is saying you can’t install a spare part for when something breaks – the general concensus seems to be, if you’ve already “passed inspection” and weighed in, and are adding a part that could put you over the 130 lb limit, you should be reweighed. If the robot is over 130 lbs, the spare part needs to be removed or provisions should be made so the robot is within the 130 lb limit with the spare.

Bottomr line: If a team is going to add something of considerable weight (not a ziptie or an extra velcro tie), they should reweigh to make sure that they will pass inspection with the new part(s) on the robot. If the robot and all of its assemblies weigh more than 130 lbs at any time, it is in violiation of rule <R06>.

I also agree that the motor cannot be installed. Let us keep separate what are spare parts and what is part of the robot during inspection. Spare parts replace whatever was on the robot during inspection, adding parts is just that - adding parts.

While there is some controversy over this rule, I think it came out of similiar threads about teams that built complete arms for their robots in the past. I remember in 2001, while in que, seeing our alliance partner take off half their robot. I went over to see if they needed help with repairs but they were just changing the arm because of our strategy.

Tristan, like for like is OK. You are changing 2 parts on the robot for identical parts AND function. When changing for two different functions then everything used for the snap on must be weighed. If you don’t weigh in both motors then you are not only violating the rule but the spirit of the rule as well. You can build 2 identical arms and ship with your robot. One is used as a spare. That whole assembly does not have to be weighed in, just the one to be used on the robot. The reason is like for like spares. Only when there are unlike replacements must they be added to the robot at weigh in time. If you weigh in one motor then that motor must be taken off your robot and put on the new function.

Now if you want to get away from gracious professionalism then you could say that you were having a problem with the old motor so you replaced with a new. Then when changing back to the out function say that you fixed the problem and that it is now OK. That is were gracious professionalism comes in. Not everything can be monitored and/or enforced. We must rely somewhat on the honesty of the teams. By the look of it when looking at the poll there are about 30% the are willing to be dishonest.

Installing the spare collar on the spare motor makes a spare assembly. This is a one-for-one exchange for the same function.

I agree with Al, the weight you play at is the weight you should weigh at. If you can play in more than one configuration, you must weight less than 130lbs in all configurations.

Wetzel

Like Katie said, I think a part stops being a “spare” as soon as it’s attached to your robot in some fashion. If that’s not the case, I know I would love to have 50 lbs of ballast on our bot to increase traction in some games.

Also, I think the rule as it currently stands is intended to prevent teams from having a giant number of configurations. This emphasizes strategizing and engineering decisions anyways, so I can’t see how it’s a bad thing, but I think that’s a discussion for an entirely different thread.

By the word of the rules, it’s illegal. My personal opinion? I don’t really care. It would save them a few minutes by not having to switch the motors if it was legal, but if the team planned a strategy that required something as major as removing and replacing an arm, I’m sure they could move the motor as well.

I have mixed feelings on this. I agree that the weight you play at is the weight you should weigh in at, but I think the spirit of this year’s rule was to put a cap on possible configurations, rather than leaving virtually unlimited potential function. Modular design is an increasingly popular trend, and I believe the rules this year were designed to prevent any one team from essentially building multiple robots. I think it’s cool to see a robot with a modular arm which can alternate from ball manipulation to hanging, based on strategy. However, a robot with a standard base and multiple toppings (say, two small ball handlers, a 2x ball grabber, and a hanger) all as separate “functions” is a bit over the top. While technologically cool, in the legal sense each topping could be considered a different robot with different functions. The spirit of this year’s ruling was to prevent this. All configurations must be weighed together to total no more than 130lbs.

To answer the original question, by the letter of the law, and from my experience as an inspector, I’d have to rule the second motor illegal if it tops the 130 pound limit. The rules clearly state the robot must not weigh more than 130lbs in ALL possible configurations, even if it’s just one more motor. Otherwise, robots could be nickel and dimed up to more weight- if you can add an extra motor on the alternate configuration why not add another motor to another function if it’s only a little over the limit.

Regarding the spare part issue- a spare part must be identical in form and function to the original part it would potentially replace. If it has different properties or different functions, it’s not a spare, and would have to weigh in as an alternate configuration, which by this past season’s rules, would have to be weighed in as part of the whole robot.

Tristan,
I would say it does not pass inspection since it is a not fully assembled attachment. It is not in the form at which it will compete and therefore cannot be weighed until complete. As an inspector I would ask that assy be finished and weighed or the team decide to leave the attachment in the pit and not use it during competition.

Al are you saying that if the 2nd assembly does not have a motor attached then it is not a functioning piece so that it cannot be used. I do not see a problem with the motor being used on both assemblies as long as it is transfered. If you weighed the robot after changing the motors there would be no weight difference. I am not sure of that part of the rule, if there is one, so could you
help me out a bit with this.

Steve,
The intent is to have all assemblies and basic robot that are used for competition weigh in less than 130. If one of the assemblies is incomplete it is not in the form which will compete. If the motor used for both attachments, were part of the basic robot then it would pass. I know that sounds a little contradictory, but the team did/could have had that chance. Moving a motor from one assembly to another to make weight does not fit into the rules in my opinion.
As a team that has competed with attachments in the past, the change in rules in 2004 made a change in our design strategy.
I need to add here that the 130 lb. weight limit is one which allows two (athletic) students and/or adults to get the robot on the field and I support that. Additional attachments that make a robot more than 130 is pushing the envelope of safe handling and I must be against that.

In understand the 130 lb weight limit. I agree that 2003 had a better rule. I also saw robots weighed in with all extra parts even though they were not complete. My belief, which is not law, was that the total weight of all pieces would weigh in at 130. In the above case there is only one motor being used. does it matter which assembly it is on. The team must remove it from one and use it on the other so it is really not a set on either assembly. In Tristan’s case there are 2 motors involved which is wrong.