[BLDC] Brushless Motor?

[Ether]

Just did a search of Chief and there's not a single post with the word "brushless" in it since Kickoff.

Just sayin'

[marshall]

Shh... you're giving our master endgame plan.

[spacepenguine]

That's probably because the only brushless motor option is a [s]giant[/s] hunk of metal more akin to a stepper... which doesn't give you the benefits of the low rev/high power outrunners in electric longboards.

I take some of that back because the motor is actually way smaller than I thought it was from first look last week. Here's the datasheet for reference. https://www.firstinspires.org/sites/...data-sheet.pdf

[GeeTwo]

Hmmm.... drive train, intakes, lift, climber, nudger. Might use it for the nudger, or to do help set the hook, but we want to get the other stuff working first.

[Joe Ross]

I just did a search and found this thread.

[Michael Hill]

We might use them for counter-balance

[techhelpbb]

Do these BDLC have a price in dollars, not points, yet?

[pkrishna3082]

Originally Posted by techhelpbb

Do these BDLC have a price in dollars, not points, yet?

$99

[cad321]

Originally Posted by pkrishna3082

$99

Keep in mind that this also includes the controller for said motor. So it is actually comparable to some other motor/controller combos out there (assuming you disregard the motors power).

[techhelpbb]

The output side of that BDLC motor is almost the size of a NEMA23 stepper which maxes out around 175oz.in but this maxes at at 40oz.in and a 175oz.in NEMA23 stepper would be shorter something as long as this BDLC in a stepper would have much more torque at the low RPM (pull out torque is over 100oz.in). Plus this BDLC draws 4A+ which even if you microstepped a stepper you could draw less than that. Course the FRC battery voltages would be kind of low and that might stop the stepping motor from being able to produce full torque.

https://www.pololu.com/product/1474

Course the steppers are not legal for FRC but you could build a 3D printer to use with FRC using them.

[Nidec]

Originally Posted by Ether

Just did a search of Chief and there's not a single post with the word "brushless" in it since Kickoff.

Just sayin'

We've been getting a lot of private messages regarding BLDC motors.

Everyone should check out the Dynamo Design Challenge and take a look at what students have designed using the Dynamo!

We are still accepting entries, so if you have a Dynamo, feel free to enter the contest!

Looking forward to seeing some Dynamos in action at regionals and the World Championship!

[Brainiac33]

I love the NIDEC Dynamo motor so much that I put the AndyMark part number on my team jacket. I had to, it's the biggest thing in robotics since wheels!



http://www.andymark.com/Dynamo-p/am-3740.htm

[Nidec]

Originally Posted by Brainiac33

I love the NIDEC Dynamo motor so much that I put the AndyMark part number on my team jacket. I had to, it's the biggest thing in robotics since wheels!



http://www.andymark.com/Dynamo-p/am-3740.htm

That is AWESOME!

[cbale2000]

Here's the trade-offs I see with these motors...

Pros:
Better Efficiency
More accurate/consistent RPM Control
Better long-term durability

Cons:
Slow (1700RPM)
Heavy (1.5lbs)
Weak (20Oz-in)

The problem I see is that most of the items in the "Pro" category are not particularly critical to FRC teams, where as the items in the "Con" category are essential... Efficiency is nice, but at the power level of this motor (44w) it's not a significant impact on battery life compared to similar brushed motors (it's like replacing a 20w incandescent light with a 5w LED when you still use 150w lights elsewhere). Durability is virtually irrelevant for FRC uses, I've never had an FRC motor burn out because of wear and tear, only from stalling. Having better control of RPM could be useful for certain situations, but most of those situations require more speed or torque than this motor can provide.

Weight is the biggest drawback here, for about the same weight I can put a bag motor, planetary gearbox, and the motor controller to run it on a robot and get 3x the power and 10x the speed of this one (before you factor in the gearbox reductions). As far as I can tell, anything you would want to use one of these motors for you could just as easily swap in a bag or 775 motor and get better performance at a fraction of the weight.

Don't get me wrong, the Dynamo is a nice motor by itself, but I feel like it isn't well suited to fill a role that's not already better filled by one of the other legal brushed motors. Either that or I'm seriously missing something here.

[Ether]

Originally Posted by cbale2000

Pros:
More accurate/consistent RPM Control

What is your source for claiming that the provided BLDC motor has more accurate/consistent RPM control than a brushed motor being controlled with Talon SRX built-in 1000Hz closed loop speed control?

Pros:
Better Efficiency

The provided motor/controller is approx 51% efficient at max power (35W).

A BAG motor is 68% efficient at 35W

but at the power level of this motor (44w)

It is not a 44W motor with the provided controller. It's 35.2 W max.