pic: 8 BLDC Closed Gearbox



this transmission is the biggest thing in robotics since wheels imo

dont @ me

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After seeing the video from Nidec, I became inspired to design a gearbox using eight of the revolutionary new brushless dynamo. This gearbox uses the high efficiency, cost effective motors to bring a new age of drive trains to FRC.

Pros:

  • Dominate the field with a 25 fps robot.
  • Control your robot with advanced algorithms using the four quadrant closed loop.
  • Take advantage of the dynamo’s high efficiency to make your batteries last longer.
  • Never wait for motors to cool down thanks to the high heat dissipation.
  • Encourage creative and elegant pneumatic designs.
  • Slim 6.21"x8.44"x5.29" profile
  • Lightweight gearbox weighing in at 14 lbs
  • Low cost of ~$850 per gearbox

Cons:

  • None.
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I feel it is worth pointing out that this will require 8 DIO ports and 8 PWM ports per gearbox.

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Or a LOT of PWM splitters :slight_smile:

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Wow, for years my team has been struggling with the oh so treacherous effects of brush wear on our FRC robot. This will solve all our problems!

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Yes, because that is the biggest problem with this gearbox.

That is a really cool graphic. I think you’re trying to tell us… why stop at 8?

By harnessing the power of fractals, we can have unlimited power on our robot!

No, the power is still limited. We can have an unlimited number of paths it takes on the way to the wheels!

Edit - and by the way, just one of each splitters is enough - if each is a bus. Or you could use two of theseon each.

Edit2 - Am I looking at this right? It looks like a single stage gearbox with two idler gears feeding the output directly.

https://i.imgur.com/cJlBUVL.gif

EDIT: I chose this design because it allows the efficiency of the BLDC motors to remain at its absolute peak (without having to go through pesky gear friction), while also minimizing the profile of the already slim gearbox. This is truly the level of simplistic and elegant design the motor was designed for.

So much power @40wattts*8

Even if you assume you can run them at peak power (88 watts each 704 total) it’s about the same power as two cims. Eight nidec’s at 1.5 pounds each is twice as heavy as two cims and two talons (12 lbs v.s. 6 lbs). It’s a shame they choose to introduce such a weak motor as the first BDC motor in FRC. Having worked with them on an electric racecar I know they can be so much better.

Where did you get 88W from? According to the data sheet, they’re 44W max. According tin Ether (who I trust more than Nidec), the published torque/speed curve says they’re only about 35W max. That means 16 motors in both sides of the drivetrain equals about 1.67 CIMs TOTAL for both sides. Just to help get a perspective of how little power “the future of robotics” contains.

Edit: if you hooked one of these gearboxes up to a properly sized drum to put them at max power, it would take about 4 seconds to lift a full weight robot in 2017. So one motor would take about 35 seconds.

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Or one 8-way Y cable. Good luck twisting that together. (At that point, it may be better to get some sort of terminal block. Or use one 3 way lever nut and 2 5 way lever nuts.)

I think I found the perfect gearbox for the ULTIMATE FRC drivetrain.

Nidec responded to me on their YouTube video saying that the real peak is actually 88. I’m thinking it comes from the difference in “rated” specs that they list on the sheet and the peak specs.