I am curious about what the approval process for creating a COTS item and/or an allowed motor looks like. I’m assuming it has something to do with creating a prototype and pitching it to FIRST. If anybody with further insight or first-hand knowledge would be willing to respond I would greatly appreciate it. Thanks all.
COTS item:
Sell item. That’s it. COTS is “Commercial Off The Shelf”. If you have an item that you think people would buy, and you build it and sell it, it’s COTS. (I should note that you DO need to be a VENDOR, which pretty much means that a) the government knows you exist for tax purposes, b) you can actually ship stuff within a reasonable time, and c) you can separate company operations from team operations.)
For a motor… that’s probably more along the lines of what you’re thinking; you’d need to make FIRST aware that your motor exists and is safe.
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Thank you very much, this makes sense. I guess since COTs doesn’t exactly require FIRST approval I will edit my question to specialize on allowed motors.
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Are you trying to get a motor you think would be good for FIRST approved or work for a company interested in donating? I have experience with the later and it was just a matter of contacting the KOP team and sending the motor information. Thinking that would go much better than just trying to get any old motor approved. If FIRST had to evaluate every single request someone would suggest it might get a bit overwhelming. Guessing they would need to consider oversaturation where it could start impacting the companies that support FIRST like VEX and AndyMark.
There’s a solid chance that’s part of the motivation here.
After all, it’d be nice to have a NEO competitor now that there is a widespread Falcon boycott for non-technical reasons. (If it were technical reasons, I’d still consider it to be a true competitor. As of now, many teams would go back to CIMs if we found out NEOs were radioactive or had some other equally debilitating technical flaw.)
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I’d say that Falcons have technical issues - all the QC issues were making me seriously reconsider using them even before the IFI scandal dropped.
To my knowledge, NEOs have never really had any major issues to the level that Falcons do, not to mention supply-chain issues.
What I mean by that is that the products would still be competing. If REV were to start slacking and the NEOs started having a bunch of problems, you could swap to Falcons if the tradeoffs were worth it.
With a boycott due to company culture, you have to ignore the technical comparison.
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I’ve discussed in on other forums, and there’s some good debate about how well it would perform, but here’s my COTS motor pitch:
I think we should allow any COTS brushless motors and PWM ESCs (within limits).
For instance, a COTS 32-bit brushless ESC like this one:
Combined with a 150 to 300W brushless, sensorless motor like these: https://hobbyking.com/en_us/propdrive-v2-2836-1000kv-brushless-outrunner-motor.html
https://hobbyking.com/en_us/trackstar-380-sensorless-brushless-motor-3800kv.html
https://hobbyking.com/en_us/propdrive-v2-3542-1000kv-brushless-outrunner-motor.html
Would make for a nice little 550 or 775 brushed motor replacement. The advantages are:
- Motors with a 5mm shaft would be compatible with COTS 775 pinions. Motors with a 3.175mm / 1/8" shaft would fit COTS 550 pinions with a little drilling / reaming.
- The ESC comes with BLHeli32 firmware, which allows you to set current limiting to protect the motor from overheating (cheaper ESCs don’t have this feature).
- The PWM input makes it safe, following the RIO’s brownout and disable instructions.
- Motors can be found in a variety of “KVs” to match torque and speed requirements.
- You might not have to regulate every motor and ESC combination - just give a max wattage or current limit. That would prevent supply shortages and international shipping costs.
- The motor and ESC together can be bought for less than $120.
The disadvantage are that a sensorless motor won’t give you any fancy motion control features, but that’s not needed for things like intakes or flywheels. We’d still have the (very excellent) Rev Spark/Neo ecosystem for fancier motor motion control programming.
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From FIRST’s point of view (from what I’ve heard; I don’t work there) it’s a safety issue.
Whenever there’s a new motor controller being offered, FIRST (or maybe NI?) does a lot of in-house testing to make sure that the motor will always stop when the robot is disabled. That used to be real easy, when everything was controlled over PWM generated by NI firmware on NI hardware. Now, it’s a lot more complex, since you have to test behavior over CAN with black-box vendor software (e.g. Phoenix) in the mix.
Even with a very simple non-FRC-specific COTS ESC, run over PWM, there would be some concern that there’s a pathological case where the ESC can get into a state where it keeps running when the signal is removed, or something like that. And obviously, FIRST can’t thoroughly test every ESC on the market.
Not saying that I agree fully, but I believe that’s FIRST’s perspective.
That’s a valid concern for sure, but isn’t that extremely unlikely with a PWM controlled Brushless ESC? It would have to keep switching the MOSFETs at exactly the right frequency to keep rotating.
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For context, I don’t know much about motor controller guts specifically, but I have a fair amount of experience with realtime embedded control systems.
I’d actually argue the opposite. Since a brushless ESC is a whole lot more complex than a brushed one (just to do the commutation right, even if you’re not doing any feedback), there’s a bunch of stuff going in software that has its own complex behavior. Rather than a very simple brushed ESC, which might do its work completely in analog and discrete logic, a brushless one is running software; CTRE uses dsPICs, Rev uses some beefy ARM uC, I think, and that one you linked mentions a 32-bit Cortex.
Since the software is always switching the MOSFETs at exactly the right frequency, the concern would be that it just “forgets” to look at the PWM signal coming in.
Which is not to say that you can’t design one safely, of course, but the more complex something is, the more (and weirder) failure modes you end up with.
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I tried to get a PWM ESC approved a couple years ago. It did not seem to me that FIRST would perform a level of testing that any common RC ESC would not easily pass. I’ve never seen an ESC continue putting output after the PWM signal shuts off. Certainly, the hardware used is similar for both FRC and RC speed controllers.
My bigger concern would be people trying to use brushless sensorless ESCs and being confused why it doesn’t work near stall, or trying to use motors that are way undersized. Students have enough to worry about, and honestly, going to hobby ESCs would increase the number of confused people asking questions and being hit with a barrage of information that’s difficult to parse. Not to mention trying to use 40A ESCs for 40A loads… “peak” and “continuous” are very nebulous words. Plus, sensored hobby motors are pretty expensive, so you’d probably only save like $50 per actuator.
EDIT: the savings would increase if FRC went to 24V or higher, but at the low voltage and high current of today, I think the benefits of approval outweigh the costs.
EDIT2: to the OP, for approving a motor, I think the process is different from approving a speed controller. For the speed controller the initial tests were something like “does it turn off when there’s no signal”, “can it withstand 40A continuously for 10 minutes”, and a couple other marginal things that I can’t remember. Donating to the KOP probably helps. For a motor, they might not approve it if you’re just going to be directly competing with REV, so you should go in with a company and an established motor controller and motor to be safe. It sounds like you’re probably not ready to front the money for that, but it can’t hurt to email someone at HQ (their chief engineer, maybe) and inquire about the process. More transparency would definitely be nice.
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Thanks for the insight, this thread has been very helpful and interesting.
I agree with the assumption that the approval process is mostly due to safety concerns.
After all, it’d be nice to have a NEO competitor now that there is a widespread Falcon boycott
To those wondering my exigence, I’m working with a team of people w/ a lot more specialized experience than I to build a prototype of a CIM class brushless motor competitor and see if it’s a feasible task.
Thanks all.
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…and, I think, Inspection plays a large part of that. Inspectors are there to keep people both safe and legal, and while making every brushed motor and ESC legal would make the legality part of the job easier, Inspectors would have to know a whole lot more to even know what they were looking at in terms of evaluating safety.
You see four NEOs plugged into a flywheel geared 3:1, and you know exactly what you’re dealing with when determining “is this mechanism safe?” You see the same thing with four (or two, or one) random motor you’re not familiar with, and you have much less of an idea what’s going on.
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On top of safety as a big factor another very important item in the case of Brushless over Brushed motors is you have much more control over optimization of power and efficiency through electronic commutation (FOC, etc). Opening the field, especially to generalize controllers which can be programmed would give some teams with those resources a big advantage to tap into motor optimization over those that don’t have the resources to do that.
Leveling the playing field is never an easy thing but I think is what FIRST tries very hard to do when deciding what motors and controllers to approve.
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I don’t think FIRST has been the slightest bit interested in leveling the field since it abandoned the Small Parts Catalog.
Raising the floor? Yes. Leveling the field? Nah.
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I think that has been relaxed over the years as FIRST realizes by putting too much focus on that you limit the potential for each team. Seems that there is still somewhat an attempt as many of those types of rules remain. Thank god we don’t have to deal with small parts anymore and spending days trying to figure out how to interface a motor with a gear, sprocket, etc. It’s really hard to completely level and keep to a high standard as you will always have those with more resources, money, etc. The reality of the real world.