General Motor Rules

[jman4747]

So I've been in the stepper thread and it brought back a sentiment that MAYBE we could open up the general motor rules such that you can use any 12V motor you can find so long as it satisfies a wattage limit (and a few other rules).

For example:

#1 No more than:
4x 340W-300W (CIM's)

6x <300W-200W (rs-775-18's & Mini CIM's)

4x <200W-50W (AM 9015's, RS-775-12, & BAG's)

4x <50W (AM PG motor & window motors)

#2 Stall current max: 140 amps.

#3 Must be COTS

#4 Must provide a data sheet (to prove the above)

#5 Must have P/N visible (to prove that #4 is not fake if necessary)

#6 Must be < $400 (2015 single part allowance)

#7 If it's on the allowed list (anything allowed in the 2012-2015 rules?) you can just use it.

Anything I missed?

Obviously inspection can take longer for any team using a lot of different motors but you could subvert this by placing an absolute maximum on non-standard motors. There is also the possibility that someone just fabricates a datasheet but at the end of the day we do trust everyone to bag and tag on their own.

Also please don't assume that the above rules are what I think will absolutely work, it is just an example.

[AdamHeard]

It'd be simpler to limit motors by form factor, with the two obvious choices to expand being the 500 and 700 sized motors. As in, any 500 or 700 sized brushed motor you can obtain as a COTS item is legal.

Both of which are inherently power limited by their size, and provide a wide range of existing COTS products to interface with.

[GeeTwo]

Would this only include brushed motors? Brushless motors and steppers would require different controllers, which is probably what's driving a lot of the standardization - ensuring that disabling the robot actually disables the actuators. Opening up to motors not from a specified list also increases opportunity lo lighten motors in what may be an unsafe manner. And what about hand-wound/homemade motors?

[R.C.]

I'd rather do any brushed motor under 350W @ 12V. Unlimited motors etc.. Teams will be limited by motor weight and the battery anyways.

[Richard Wallace]

I hate it when motors halt and catch fire. A bad day usually results.

A motor with too much stall current and not enough heat capacity should not be on an FRC robot. Combining Adam's and R.C.'s criteria might work.

[orangemoore]

Originally Posted by R.C.

I'd rather do any brushed motor under 350W @ 12V. Unlimited motors etc.. Teams will be limited by motor weight and the battery anyways.

I think the number of outputs on the PDP would be the limiting factor.

[jman4747]

Originally Posted by GeeTwo

Would this only include brushed motors? Brushless motors and steppers would require different controllers, which is probably what's driving a lot of the standardization - ensuring that disabling the robot actually disables the actuators. Opening up to motors not from a specified list also increases opportunity lo lighten motors in what may be an unsafe manner. And what about hand-wound/homemade motors?

I mean brushed motors. That and the wattage/current limits from the op are meant to reduce the effect on the rules and inspection by not requiring additional rules for control electronics. The same controllers would still be able to be used.

[Michael Hill]

Originally Posted by AdamHeard

It'd be simpler to limit motors by form factor, with the two obvious choices to expand being the 500 and 700 sized motors. As in, any 500 or 700 sized brushed motor you can obtain as a COTS item is legal.

Both of which are inherently power limited by their size, and provide a wide range of existing COTS products to interface with.

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?)

[Chris is me]

Is 6 cims, unlimited quantities of half a dozen other motors really not enough variety? We have cheap motors, durable motors, equivalent motors from multiple suppliers, and different size / power motors available; plenty of options. I really think at this point opening up the motor rules further is solving a problem that doesn't exist.

If they are opened up, being able to choose any 500 / 700 series motor seems like the logical next step, but other than that, I'd rather not have teams get competitive advantages from being able to source some super obscure motor that no one else has in stock / knows about.

[EricH]

Originally Posted by Chris is me

Is 6 cims, unlimited quantities of half a dozen other motors really not enough variety? We have cheap motors, durable motors, equivalent motors from multiple suppliers, and different size / power motors available; plenty of options. I really think at this point opening up the motor rules further is solving a problem that doesn't exist.

DITTO.

[geezer]You young whippersnappers don't know how good y'all have itI Back in my day, we only got 2 drill motors (there's the drivetrain!), a couple o' window motors, a van door motor, pair of Fischer-Price motors (something like a 700-series motor would be about right powerwise), maybe a CIM or two, and who knows you might get a seat motor or two if you was lucky. We only had them motors to power the whole robot! And we liked it--them being delivered in the kit saved us from walking uphill in the snow both ways to get 'em from the post office! Then some wiseacre dropped the drill motors for two more CIMS, canyoubelieveit. And we liked it more! And you're complaining that 6 CIMS and all these other really really nice motors ain't enough???? Why I oughtta get out o' this here rocker and come show you how it's done! Open up the motor rules? They already been opened up![/geezer]

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.


Now, speaking as an inspector: If teams can't even get the numbers right (you'd think that black with a white background, with a given size, spelled out quite clearly in the manual, would be really easy to do), and a missing BOM is a common reason for not being able to pass on the first day of inspection, do you really think they'll remember to bring their datasheets? (For that matter, it seems like every year somebody pulls out a Globe motor, asking what it is--and has to be told it's illegal. At least a lot of them do it on CD before bag day so it can be swapped out.) I really can't say that this is a great idea...


I think someone is missing part of the point of the motor rules. The point of the motor rules is to give every robot the same available maximum power (well... OK, it used to be, until certain motors were classed as unlimited). It also ensures that everybody is using the same motor types--sure makes troubleshooting and spares a lot easier when you can ask a neighboring team and get a motor/help, rather than having to phone the home shop for your spare motors that you forgot.


Rather than loosening the motor rules...

I might suggest limiting the motors to 4 CIMs, 2 Mini-CIMs, 6 775s, 550s, and/or BAG motors (any combination), 3 PG-71s, and unlimited "automotive" motors (window, seat, door). Servos and electric solenoid actuators remain unlimited. Plenty of power in that batch...

[AdamHeard]

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?)

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

[jman4747]

Originally Posted by EricH

DITTO.

[geezer]You young whippersnappers don't know how good y'all have itI Back in my day, we only got 2 drill motors (there's the drivetrain!), a couple o' window motors, a van door motor, pair of Fischer-Price motors (something like a 700-series motor would be about right powerwise), maybe a CIM or two, and who knows you might get a seat motor or two if you was lucky. We only had them motors to power the whole robot! And we liked it--them being delivered in the kit saved us from walking uphill in the snow both ways to get 'em from the post office! Then some wiseacre dropped the drill motors for two more CIMS, canyoubelieveit. And we liked it more! And you're complaining that 6 CIMS and all these other really really nice motors ain't enough???? Why I oughtta get out o' this here rocker and come show you how it's done! Open up the motor rules? They already been opened up![/geezer]

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.


Now, speaking as an inspector: If teams can't even get the numbers right (you'd think that black with a white background, with a given size, spelled out quite clearly in the manual, would be really easy to do), and a missing BOM is a common reason for not being able to pass on the first day of inspection, do you really think they'll remember to bring their datasheets? (For that matter, it seems like every year somebody pulls out a Globe motor, asking what it is--and has to be told it's illegal. At least a lot of them do it on CD before bag day so it can be swapped out.) I really can't say that this is a great idea...


I think someone is missing part of the point of the motor rules. The point of the motor rules is to give every robot the same available maximum power (well... OK, it used to be, until certain motors were classed as unlimited). It also ensures that everybody is using the same motor types--sure makes troubleshooting and spares a lot easier when you can ask a neighboring team and get a motor/help, rather than having to phone the home shop for your spare motors that you forgot.


Rather than loosening the motor rules...

I might suggest limiting the motors to 4 CIMs, 2 Mini-CIMs, 6 775s, 550s, and/or BAG motors (any combination), 3 PG-71s, and unlimited "automotive" motors (window, seat, door). Servos and electric solenoid actuators remain unlimited. Plenty of power in that batch...

The problem isn't lack of options or power it's that the rule is based on P/N not power limitations. I wish I could use dill motors or FP's or any of the 500 & 700 series motors I could find but I can't because they aren't a specified part number.

As others hint the actual limiting factors include the PDP ports, snap action breakers, main breaker, battery, robot weight, motor controller specs, the fact that it must be a brushed DC permanent magnet motor, and physical size of the motor. The amount of power available is already limited. I found an old drill with an "FRS-550" in it and even found a data sheet to prove its similarity to the BB RS-550 but I still couldn't use it. Why? Because it's not that one part number. It doesn't really make sense.

The point is to limit DC brushed motors by voltage, power, and or current not P/N. Just look at how the CIM has to have 9 different P/N's in the 2015 rule book.

[IndySam]

Originally Posted by EricH

I might suggest limiting the motors to 4 CIMs, 2 Mini-CIMs, 6 775s, 550s, and/or BAG motors (any combination), 3 PG-71s, and unlimited "automotive" motors (window, seat, door). Servos and electric solenoid actuators remain unlimited. Plenty of power in that batch...

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.

[Gregor]

I don't mind the 2015 motor rules, but I would like to see some sort of limit in drive motors in contact games, as the drivetrain arms race is not fun.

[Kevin Leonard]

Originally Posted by Gregor

I don't mind the 2015 motor rules, but I would like to see some sort of limit in drive motors in contact games, as the drivetrain arms race is not fun.

+1
All that a drive motor arms race does is reward teams with more resources. Increased motors can be helpful for doing things like climbing the pyramid in 2013 in a reasonable amount of time, 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.