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DD-Wheel with Hoverboard Motor

Discussion in 'Direct Drive Wheels' started by Benu, Jan 21, 2019.

  1. danove_b

    danove_b Active Member

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    I borrowed some hardware from another project I am working with and tried to make my hoverboard motor to run. Thought I could just run it synchronously without encoder but I ended up connecting the built in hall elements and used them. I'm far from an expert when it comes to this kind of things, but I wonder if this motor really is supposed to be powered with sinusoidal. I connected a signal to one of the analog inputs so I could fine tune the commutation angle, but still was not able to make the motor to start by itself. @Benu Have you coded the sinusoidal code by yourself or is it some library that can be found? I understand that the vibrations comes from that the steps in the sinus voltage is 60° instead of 1.4° that I have plan to use, but there still something wrong when I cannot get the motor to rotate by itself when I fine tune the angle. Also, shouldn't it be possible to run it with a fixed frequency without commutation?
    https://photos.app.goo.gl/vNTUaA7pLynpeA1Y9
  2. danove_b

    danove_b Active Member

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    Update! Bad soldering on the hardware gave me a 2.5 phase solution... (The negative source was missing on one of the half bridges...) Now it works great! Although I have only the hall elements to get angle, it works fine.
    https://photos.app.goo.gl/3a98EpwsCtQyLLHx6
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  3. Benu

    Benu Member

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    That‘s great news!
    With the hall encoders you will get 90 ppr. That may not be enough when motor is hardly moving during gameplay.

    Today I tested the limits of my hoverboard motor. I was able to get it to 14 Nm @ 12 V. That made the motor squeak and blew the fuse of the multimeter. But other that that everything survived. I would say the highest reasonable torque output is 12 Nm. To get that I needed 13.9 A @ 12V. I made a video of the test. Will find a place to make available.
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  4. Benu

    Benu Member

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    I am using the tools from STM. Mainly „Motor Control Workbench“, „CubeMX“ and the „FOC/PMSM Library“. As development IDE „Atollic TrueStudio“. All these tools are free to use when using an STM micro controller. That's a lot of power at your fingertips for free.
  5. Gadget999

    Gadget999 Active Member

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    that is an awesome amount of torque - these motors could be good for a motion sim

    how many watts is each motor ?
  6. Benu

    Benu Member

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    The manufacturer of the hoverboard states the complete board as 500W. So I assume that will be 250W per motor. However there is no imprint on the motor.
    You will find equal sized motors rated 350W on the internet. The wiring for the coils will probably be stronger then.
    Last edited: Mar 10, 2019
  7. Benu

    Benu Member

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    Here you go. This is a video of a torque test ramp with the 250W hoverboard motor at 12V. You better watch it in 1080p.
    The lever is 0.5m.
    The scale is measuring kg.
    The Amp meter is in series with V+ from 12V power supply to the inverter board.
    The inverter board is a X-Nucleo-IHM08M1 and im combination with the Nucleo-F303RE capable of FOC.

    To get the Nm you have to
    (scale in g / 100) * (lever length in m) = Nm

    Up to 12 Nm the motor is ok. No funny noises or glitches. Above that you hear sizzling sounds and some squeaking. The Amps used are also quite reasonable.
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  8. danove_b

    danove_b Active Member

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    Think I'm finally found what I have been looking for to get the position from the hoverboard motor.

    https://www.aliexpress.com/item/50x...78-4e55-b4ae-14f0a53676eb&transAbTest=ae803_5

    Anyone that have some experience with this kind of wheels? I also found wheels with rubber, but I think silicon should give more friction...?

    My plan is to line up the encoder with this wheel on the backside of the wheel in a 90° angle.
  9. Benu

    Benu Member

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    Here you find two laps at Monza (ACC EA) with the DIY Hoverboard motor DirectDrive-Wheel. In-Game FFB gain was set to 90%. Please bear in mind, that my only comparison is a Logitech DFGT.

    Compared to that it feels much more responsive. The forces are much higher and more detailed with the DD-Wheel. Max torque was set to 8Nm. Above that overcurrent protection of the inverter board kicks in when you have to counter-steer high forces and receiving strong bumps to the front wheels.

    But at 8Nm everything is OK. I like the details and responsiveness. You see the strength of the wheel at Curva Grande (T3) and Ascari (T8, T9, T10).
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  10. Benu

    Benu Member

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    Sorry, I have no experience with these kind of wheels. You would have to make sure there is no slip. Otherwise you will lose position and your sine-waves will be out of sync. I think this will be quite difficult to keep that sync over e.g. the period of a race.
  11. Gadget999

    Gadget999 Active Member

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    thanks for the video

    I am confused how a 250w motor can be so powerful

    I have been looking at a 1kw motor for a ball screw - it is only 2.7 nm from what I can make out

    does any one have an explanation ?
    Last edited: Mar 10, 2019
  12. Gadget999

    Gadget999 Active Member

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    @Dirty - can you explain how a 250w motor can have 12nm of torque ?
  13. Alexey

    Alexey Well-Known Member

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    The watt rating of a motor is not the maximum attainable power from the motor. That torque figure would be reached at stall and drop off as rpm increased.
    Different types of motors also use less power to make more torque due to design and motor type.
  14. Dirty

    Dirty Active Member Gold Contributor

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    Yes :) I guess :)

    I have only read the last few posts on this thread, so I don't really know much of the context, but I will try to clear things up:

    Try to understand the difference between torque and power. These two are often named in the same context, but are essentially two completely different things. I am trying to be precise here and still keep it as simple as possible.

    In electrical systems Power = Voltage * Current so, if your motor consumes 10,41 amps (current) at 24volts (voltage) it will consume 24*10,41 = 250 Watts of power. Period! Whether you want to turn that power into torque or RPM is completely up to you. Eventually this power will end up in a mechanical system, so lets take a look at how those deal with power:

    In rotating systems Power = Torque * RPM so, if you put those 250W into a rotating system, you will get rotating motion. This rotating motion will have a certain torque and a certain RPM. It depends on the motor construction whether you will get higher torque or higher RPM, but whatever the construction, if you put in 250W of power, then Torque * RPM will ALWAYS give you 250W of power.

    You can construct a motor in a way that it outputs 1.000.000Nm of torque if you are willing to accept that it will only run at 0,002387 RPM. :thumbs

    --------------------------------------------------------------

    More practical: I guess you want to find a motor for a control loading system of a steering wheel in a driving sim.
    1. Ask yourself: "How fast will this thing spin at max". I'd say a full left deflection to a full right deflection will be 360° and you could do that in 0,3 seconds. So it will have a max angular velocity of 360°/0,3 s = 1200°/s =
    2. Divide by 360 to get revolutions/s. 1200/360 = 3,33 [revolutions per second]
    3. Multiply with 2π (~6,28) and you will get a max angular velocity of 3,33 * 6,28 = 20,94 [radians per second].
    4. Ask yourself: "How much torque in Nm do I want to have on the wheel?" (2Nm isn't much, 20Nm is a LOT!) Let's take 10Nm.
    5. Multiply 20,94 [rad/s] * 10 [Nm] =~210W motor power required.

    ...then take a little more than that, because of losses.

    If you want to use it as a direct drive system I'd search for a motor that has at least 250W of power and delivers that power at 200 RPM (that's the 1200°/s we need)

    Bottom line: Don't mix up torque and power. You will have to satisfy the requirements of both.

    I hope that wasn't too confusing. :)
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  15. Dirty

    Dirty Active Member Gold Contributor

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    ...then I guess your motor will run at ~3500RPM while it produces 2,7Nm. Great motor for a ball screw! Just not for a direct drive wheel. :)

    @Benu 's numbers make perfect sense as well. But I guess that motor will not be able to keep it's 12Nm at speeds of over 200RPM, right?
  16. danove_b

    danove_b Active Member

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    Yea, I thought of that also, but I will also connect one of the hall elements so I can reset/adjust the position every time I've get a signal from it. That idea was born when I had plan to use a optical mouse as a position sensor
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  17. Benu

    Benu Member

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    Yes, the motor can easily be slowed down a bit but stopping it is far more difficult.
    The motor will do max 170RPM running at 12V. Running it with the hoverboard battery at 36V gives 510RPM.
  18. Dirty

    Dirty Active Member Gold Contributor

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    Right. I think I remember that stopping an electric motor is equivalent to shortening the circuit. Look at the circuit of a DC motor. It effectively IS a short circuit, if it weren't for Lorentz force. Maybe someone with a deeper knowledge of motors can chip in here, but stopping a motor will (in theory) let the current go to infinity.

    When I designed this, I planned on using Clearpath Integrated Servo Systems (MCVC-Series). You can set them into "follow digital torque command" Mode. So the internal control loop (closed loop, I think) takes care of maintaining torque for you. You just tell it what torque to produce and it will apply THAT torque to the shaft. Great motors, but not cheap.
    1_-_RIG_2017-Dec-05_02-53-55PM-000_CustomizedView56387974274.png 1_-_RIG_2017-Dec-05_02-52-23PM-000_CustomizedView50710700853.png 1_-_RIG_2017-Nov-23_04-45-07PM-000_CustomizedView14489540221.png 1_-_RIG_2017-Nov-21_09-29-29PM-000_CustomizedView34355736573.png

    Dirty :)
    Last edited: Mar 11, 2019
  19. Gadget999

    Gadget999 Active Member

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    Thanks for the reply, I did not realise a hoverboard was such a low rpm.

    The design of the motor is integrated into the outside of the wheel so i guess the torque is greater becasue the coil is a larger diameter.

    @Dirty are you an engineer/physicist ?
  20. Frederiksen

    Frederiksen New Member

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    I finally got the 15% off eBay coupon I've been waiting for but now this hover board motor idea looks better. Should I wait for the hoverboard motor idea to be solidified or just go with the my1020? If I understand correctly many of the components are different for the two ideas. The only thing I have so far is an Arduino Leonardo. Also do you think the hoverboard idea can be accomplished for about $150? Thanks for the help.

    Please hurry as this coupon ends at 7pm PST lol
    Last edited: Mar 12, 2019