General Motor Rules

[Knufire]

Originally Posted by Kevin Leonard

...but in 2015 we had to make a total of zero trade-offs when it came to alotting motors. 20's elevator had 4 motors on it, for example.

Exactly why I agree with EricH about having stricter motor limits. Having to make significant tradeoffs in how much power to allocate to what mechanism is a fun part of design and encourages creative solutions vs. lets just throw more motors on it until it does what we want.

[Thad House]

I think requiring 12V motors isn't a good idea. The RS-775 everyone uses is an 18V motor, and it runs great, partially because its never running more then 66% of what its rated for. I think the watt and amp limits need to be counted at 12V, but if you want to use a motor rated for higher voltage you should be able to do so. The battery already limits to 12V.

[thefro526]

Originally Posted by Michael Hill

I'm curious, is there some written standard for 500/700 series motors? All I've found are actual Mabuchi part numbers as well as other motors claiming to be 500/700 series motors for RC toys. (Or did Mabuchi just set the standard?)

Originally Posted by AdamHeard

I've never sought one out, but i'm sure it exists.

I did some digging and wasn't able to find a comprehensive standard that covered any given series of Mabuchi motor, but it looks like it'd be simple enough to allow any motor with a Mabuchi part number of of "RS-3XX", ,RS-5XX" or "RS7XX" to be used in FRC, since we've already seen these motors in the KOP (virtual KOP?) at least once.

Personally, and this is only my opinion, the motor rules as currently written, and previously written (at least as long as I've been in FRC) - dont work. I've seen at least two or three robots a season - usually at events where you've got a lot of "one and done" teams, that use illegal motors, usually something from a previous KOP.

I honestly can only think of one time where any inspector ever cared about motors to the point where they checked part numbers, and that was back in 09 - there were three or four RS500 motors at could be used... (Only one of them made sense... We did not use that one) so the inspectors knew to verifying part numbers.

We're almost at a cross road, either limit the motor rules, specifically to CIMs, Mini-CIMs, Bags, 500 cans (AM-9015?) and 700's (AM PG series?). At that point, between the visual uniqueness of the CIM family compared to most other motors, it's hard to mistake one motor for another, and AM has a colorful enough label that it jumps out. (Although RS775-18's are awesome, someone make a colorful label.)

The alternative would be to limit max power win an open(ish) motor list. I think this actually may solve the problem, at least for the most part - but you still run into instances where the same motor may have different specs depending on the vendor - not to mention that you'll have a handful of teams ripping apart drills and other tools to pull motors out, with no real way of verifying the specs.

IMO, in a perfect world, motor allotment is any combination of CIM's, Mini-CIM's, BAGs and RS-series motors under a total of ~3.5-4kw of power. After that point, if you're really using all of that, your batteries will rarely last a match, which creates more problems than it solves, obviously. It also forces teams to make smart decisions about where to use power and where not, rather than the current "all CIM everything". (Although a 3.5kw cap does not prevent one from doing all CIM everything, it just limits what they can do with that mentality.)

[Paul Copioli]

I think we should just use all Mini CIMs and BAG motors.




There will be those that get the joke and those that do not ...

[EricH]

Originally Posted by Paul Copioli

I think we should just use all Mini CIMs and BAG motors.




There will be those that get the joke and those that do not ...

You mean IFI hasn't developed a 700-series motor yet? Or a BIG CIM? Seriously?


Yep, I get the joke.

[Richard Wallace]

Originally Posted by Paul Copioli

I think we should just use all Mini CIMs and BAG motors.

Good idea. And smoking motors should be an automatic yellow card.

[Scott Kozutsky]

Originally Posted by EricH

Seriously, folks. If the motor selection currently available doesn't fit your needs, you may want to reconsider how you're doing things. Try pneumatics.

Originally Posted by IndySam

Amen, teams have way to many powerful motors now. We need to get back to the days of having to make decisions about where to use the most powerful motors. I miss this design challenge.

I couldn't agree more. My personal preference would be 5 CIM motors (can be freely downgraded to minis), 3 minis (plus downgraded full ones), 5 combined RS/bag/PG motors and unlimited auto motors.

It would also be interesting to see a year with a very strict motor allowance. 3 cims, 4 minis, 4 combined RS/bag/PG motors and unlimited auto motors for example.

What I really think we need is a CHEAP motor controller for the smaller motors. You don't need to withstand 100+ amps of surge current for a window motor. It would also give some much needed utility to these motors.

I inspected a team which used 1 speed controller for 2 cims. It was a bad mistake but it just goes to show that we don't need more complex rules. On that note: open up the servo restrictions.

[EricH]

Originally Posted by Scott Kozutsky

On that note: open up the servo restrictions.

THAT one, I'll go for. 4W is pretty weak.

I'd say to allow all micro-servos, and any hobby servos up to some reasonable wattage (10W, maybe? 20? Just throwing some numbers out here...), but nothing that isn't a hobby servo (AKA, nothing industrial).

[jman4747]

Originally Posted by Scott Kozutsky

I couldn't agree more. My personal preference would be 5 CIM motors (can be freely downgraded to minis), 3 minis (plus downgraded full ones), 5 combined RS/bag/PG motors and unlimited auto motors.

It would also be interesting to see a year with a very strict motor allowance. 3 cims, 4 minis, 4 combined RS/bag/PG motors and unlimited auto motors for example.

What I really think we need is a CHEAP motor controller for the smaller motors. You don't need to withstand 100+ amps of surge current for a window motor. It would also give some much needed utility to these motors.

I inspected a team which used 1 speed controller for 2 cims. It was a bad mistake but it just goes to show that we don't need more complex rules. On that note: open up the servo restrictions.

The point was not to increase the arbitrary power limit but to limit the power by setting a direct limit on power. Right now the limit is indirectly set by specifying how many of each specific motor a robot can have. I am proposing that either it be set by a total watt limit, a categorical watt limit (see op), or similar method. The limits in the first post can simply be reduced to satisfy a reduced power allowance.

In short the point was to increase the number of different motors we could use not the total wattage of what can legally be attached to the robot.

Edit: I too would like to see an increase in both the servo and solenoid wattage limits.

[EricH]

Originally Posted by jman4747

The point was not to increase the arbitrary power limit but to limit the power by setting a direct limit on power. Right now the limit is indirectly set by specifying how many of each specific motor a robot can have. I am proposing that either it be set by a total watt limit, a categorical watt limit (see op), or similar method. The limits in the first post can simply be reduced to satisfy a reduced power allowance.

Why? Really simply, why? What exactly is the current motor restriction not allowing you to do that you need to do?


Is it just that you want to use a different motor? OK, submit the idea to FIRST to see if they can get the company interested in supplying 3K motor "sets" (a set being anywhere from 1 to infinity motors). A different type of motor altogether? In that case, I ask why you really need that functionality, and look for workarounds. Or is there something I'm not seeing? (I honestly don't see any application for stepper or brushless motors that can't be handled with an additional sensor on the robot and careful motor selection.)


In the real world, the customer doesn't relax requirements just because "it should be this way". The customer only relaxes the requirements if it can be conclusively shown to their satisfaction that the requirements must be relaxed in order to meet other requirements--and usually, that can't be shown! Again, FIRST imitates life...



Now, I bet someone is going to come back with "well why do you favor the servo limits increasing?" And my answer is that it is nearly impossible for teams that don't want to use pneumatics to have multiple speed drivetrains with the servos we have. I've seen teams gang servos to get the required power for some relatively minor jobs. I've very, very rarely seen a servo used on a robot--a "gate latch" a few years ago being one of the cases. Plain and simple, there just isn't enough power available in that group.

[pmangels17]

Full disclaimer: I am not a robot inspector, nor have I ever been, but I have been at all of my teams robot inspections from 2011-2014, and I feel that that qualifies me to say what I'm about to say, which has already been echoed in this thread.

Why are we going to make the inspectors' jobs more difficult? Any team that cannot accomplish what they want to build with the motors currently available has bigger issues that the available motor selections. Any team that is going to gain a slight performance boost from some obscure motor somewhere probably already soars above the competition with regard to whatever they are trying to improve.

So, back to the big question, why make inspections harder? Every interaction I've had with an inspector has led me to the conclusion that they are there to make sure that our robot gets on the field and doesn't explode/hurt people/break other robots with fire/anger insurance agents, and THEY ARE THERE FIRST AND FOREMOST TO HELP. Opening up the motor rules would require teams to bring in documentation and prove that their motors are indeed what they claim they are (with data sheets, etc, that teams will inevitably forget to provide). On top of that is the problem that motor spec sheets don't always have accurate data in the first place (BaneBot 550), so now inspectors have to judge whether those high school kids with the wire birdsnest plugging in random motors they found on eBay that draw 100+ amps of current are safe and within the confines of the rules. Rules, I might add, that solved a problem that didn't exist in the first place.

So, in short, opening up motor the allotment solves a problem that doesn't exist and creates unnecessary headaches for volunteers that already have a lot of stuff on their plate, all while lengthening the inspection process, and in the process slowing down the teams that followed rules to the T and now want to get on the field on practice day.

My vote would be, go back to the motor rules we had in 2011. There were enough motors there to do whatever we wanted, not enough for a drivetrain arms race, and just enough limitation that teams were forced to make tradeoffs on design. For posterity, those rules were: 4 CIM's (we could say now and/or MiniCIM's), 4 Banebots, FisherPrice Motors from the KOP, window motors from the KOP, and maybe now a couple AndyMark or BAG motors

[Kevin Leonard]

Originally Posted by pmangels17

My vote would be, go back to the motor rules we had in 2011. There were enough motors there to do whatever we wanted, not enough for a drivetrain arms race, and just enough limitation that teams were forced to make tradeoffs on design. For posterity, those rules were: 4 CIM's (we could say now and/or MiniCIM's), 4 Banebots, FisherPrice Motors from the KOP, window motors from the KOP, and maybe now a couple AndyMark or BAG motors

Similar motor rules to 2011 makes a lot of sense.

4 CIMs, 2 MiniCIMs, 4-6 BAGs/Banebots/AM/Fisher Price, Unlimited Window motors/Servos

If you need more motors than that, I don't know what to say. (20's 2015 robot had 12 motors on it: 4 CIMs, 6 BAGs, and 2 window motors. The original version of it had 4 CIMs and 8 BAGs, but without the window motors)

[Gregor]

I'd like to see more than 4-6 BAG/BaneBots/AM motors, but more strict CIM and miniCIM restrictions would be appreciated. Unlimited miniCIMs is just absurd.

[Jared Russell]

Originally Posted by Gregor

Unlimited miniCIMs is just absurd.

Why?

[AdamHeard]

Originally Posted by pmangels17

Full disclaimer: I am not a robot inspector, nor have I ever been, but I have been at all of my teams robot inspections from 2011-2014, and I feel that that qualifies me to say what I'm about to say, which has already been echoed in this thread.

The proposal to open up 500 and 700 sized motors makes it easier for inspectors.

Does it look like a 500 or 700? Well it's most likely legal.