Hub motor for full-size domestic robots


Do we really want robots with loud gearmotors? No, we want the simplicity, extreme reliability, and quiet operation of direct-drive brushless motors. So say we all! The RoboWheel is a large brushless hub motor (powered wheel) with a high-resolution internal quadrature encoder and exceptionally low cogging, intended for large domestic robots or similar projects needing mobility. This is not open source (explanation below).

  • Approximate diameter of rolling surface: 170mm
  • No gears; completely silent
  • 27 poles and 1.7Ω winding resistance for low cogging
  • Integrated 3200 PPR quadrature encoder
  • Operating voltage: 7-42V
  • Recommended controller: Pair with the NearZero to command with a few lines of Python on a Raspberry Pi or other common SBC, or use the PWM outputs of an R/C receiver

  • Documentation & Files:

  • Datasheet: Pinouts and mechanical specs
  • Mechanical model: STEP file
  • Optional Bracket: STL files
  • Video: A thorough description of the RoboWheel and the NearZero controller

  • Related Products:

    NearZero -- Brushless motor controller for robotics
    Robotics Mobility Package -- 2 Robowheels and 1 NearZero controller, discounted
    Mounting Bracket -- Bolt the RoboWheel to a horizontal surface

    Personal note from the applications engineer:

    Why is this not open source? Here's what happened:

    When I decided I wanted to build large domestic robots I quickly decided that such a thing should be driven by large, quiet, reliable, brushless hub motors. I was surprised to see that I couldn't buy these anywhere, so I decided to make my own.

    I then thought "well I'll need a controller for that, dum dee dum, let's see what's available", and was flabbergasted that I couldn't find a controller that could do slow-motion precise positioning of something like a hub motor that didn't cost many hundreds of dollars. I then though, OK, the controller will have to be the first product, and THEN the hub motor, and THEN the full size robot. Flash forward a year or two and I finally had the controller ready, and this is the NearZero.

    Now I was ready to go back to the hub motor design which by then I'd decided to call the RoboWheel. Some progress on this was made even during the NearZero development and I'd prototyped the wheel casing in aluminum to a relatively high level of refinement, and had hand-wound more stators than I cared to.

    Unfortunately (well, maybe fortunately), by this point I found that the rest of the world had caught up and it was now possible to import precisely the kind of hub motor I was envisioning for the RoboWheel: High pole count, high winding resistance, built-in encoder, and a mounting flange instead of an axle. The motor I identified that meets these criteria is in fact stupidly similar to my own prototype for the RoboWheel, so, realizing it would be absurd to re-invent the wheel (haha!) I decided to slap the 'ole Sky's Edge Logo on this, call it the RoboWheel, and distribute it as a "white lable" product. The nice Chinese manufacturer even did the laser engraving for me. So that's that. It's not open source, but it's filling a need.

    ~Justine Haupt

    RoboWheel RW170:

    $110 USD


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