FRC Blog - 2019 Motor Controllers and MXP

One thing to keep in mind here is that the coil on this motor is static and coupled to the aluminum front face of the motor. So when bolted to any aluminum gearbox or other structure your robot is a good heat sink. I won’t claim that they are unkillable, but with the integrated temperature sensor and current limiting they should stand up just fine.

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I am going to speculate differently. I think performance is quoted at 40A because that’s the most continuous current available to teams via legal breakers, and therefore a useful data point.

I would not be surprised if the motor is actually capable of much, much more than 330W of mechanical power, but at some point the motor and/or controller won’t be very happy about it for long. It’s common for sensored BLDC controllers have some smarts to limit the output to a safe envelope.

I wonder if the hall sensor will be used within the new motor controllers software to detect position, velocity etc. That would be nice to have all that feedback without extra wires and software integration.

Yes.

Well I’m sold, what’s the catch?

The catch is that they’re not available now and I don’t trust anything in my drivetrain that I haven’t seen driven into a wall for 2 minutes. :rolleyes:

Working on getting these installed on 2018 TechFire 225’s robot. :slight_smile:

https://imgur.com/gallery/GKvjdsY

Video coming soon. :slight_smile:

Please have a video of it driving into a wall for 2 minutes. :rolleyes:

Edit; the cylinder is now the further protrusion off that shifting gearbox. It’s like 2006 all over again. Time to find some even shorter pancake cylinders!

If possible, please post as much material as you can (around kickoff time) concerning how the motor performs and how to use it in high power applications. We haven’t had a high power brushless motor in FRC before, so nobody knows how it works. If you can demonstrate the advantages of it, more people will jump on board and implement these motors in their designs.

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Here are some videos.

We were only running one motor during these on a 3 CIM ball shifter transmission in high gear for testing.

We hope to have everything running tomorrow with 2 REV Brushless motors in each transmission and then will be testing on our elevator.

So stoked for these motors.

We plan on doing a pushing test between our competition robot with 6 mini-cims vs 4 REV Brushless and in the future 6 REV Brushless. :slight_smile:

I’m also really interested to see how much activity it will take for those motors to affect the plastic housing on the gearbox

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Can Victor SPXes be natively made followers of a SPARK MAX? I expect not since they’re made by different companies, but it would be pretty nice to save some money.

We have a feature in our software that allows you to salve a SPARK MAX off a talon or victor. CTRE/VEX just needs to update their firmware to allow it, but it is possible.

Victors won’t be able to drive the NEO. Brushed and brushless motor controllers are fundamentally different. The easiest way to see this is that the NEO has 3 wires for power whereas the Victor has 2 for output.

Something that’s been nagging me ever since I’ve seen these GORGEOUS motors is the motor response curve. The brushed DC motors we’ve been using in FRC are pretty linear, all things considered, and so there’s a fairly direct correlation between voltage and velocity. As I understand it, it’s considerably different for BLDC motors. Is the nonlinearity compensated or in the Spark MAX? Or do we just grit our teeth and choose to deal with it in our robot program?

Perhaps you guys could comment on how it feels to drive the robot with these motors attached and/or the process of programming them? It’d be interesting to me (as well as for others) from a driver-control standpoint as well as a control systems standpoint.

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I know. But the MAX appears to be able to drive brushed motors with closed loop control as well as BLDC motors.

So I have been lucky to play with the test batch of Rev motors. I am working closely with Donnie on 225 and what I can say right now is 25 pre-order a bunch of these motors and controllers. IMO they will be game changers as the size (footprint) is smaller they as power if not more then cims and weight about 2 pounds less. We will show our results once we get more data in.

For those of us that use Mini-CIMs on drive train it is 1lb 4.5oz lighter than Mini-CIM.

Just sayin… And if you look at the pictures posted earlier the amount of room is amazing, We took picture of REV Brushless on left and Mini-CIM on right you can see the difference.

I’d love to see stall and max power curves like VEX has done, but on its face it sounds like you’ve got an awesome product and likely gamechanger.

Brushless motors and brush motors both have linear speed/torque curves. Typically the motor controller causes any non linearity normally due to current limiting. BTW a Talon running a motor in current limit takes the top off the speed/torque curve, as it should.

Both motors runnin’ all out have linear curves.