I'm looking to play around with making a massage pad that I can lie down on and has massage nubs that are motor driven. There will be a motor that rotates the nub (the part that does the actual massaging) and motors that translate the nub in 3D "space".

I'm wondering if there's a good way to choose which motors are appropriate for my application. I understand the difference between motor types but don't know how to calculate torque required in this scenario. Perhaps there are other motor specs to consider too.

Thanks so much for any guidance you can offer!

  • $\begingroup$ If this is a DIY project or a prototype, don't bother calculating the torques required. Just get motors that are more powerful than they need to be and throttle down the power using a motor controller. Also, the most efficient way to do this would be to have one motor and then drive all the nubs using a geartrain (which could even achieve the compound rotation/translation motion planetary gears in places, as long as the translation was an "orbit"). $\endgroup$
    – Emily Conn
    Jun 22, 2022 at 14:41

1 Answer 1


You will need numerous motors in a small space, this means small motors. The current state of the art in small electric motors is the brushless DC motor as used in drones and model airplanes. These are small yet powerful, readily available, and there are a number of driver boards optimized for them which are used in the hobby robotics field which are in turn controlled by arduino, beaglebone, or raspberry pi devices.

  • $\begingroup$ Thank you so much for the direction Niels! Any idea how I'd go about determining the torques and other motor specs I'll need? $\endgroup$
    – MrBaba
    Sep 28, 2020 at 11:32
  • $\begingroup$ that would be by experiment. -NN $\endgroup$ Sep 28, 2020 at 16:12
  • $\begingroup$ Got it. But do you know by experience the ball-park of motor specs I should be looking in? If not, do I need to buy 20 different motors to do the experimentation? Or could buying 3 already whittle things down significantly? $\endgroup$
    – MrBaba
    Sep 28, 2020 at 18:45
  • $\begingroup$ start small with a drone motor. buy bigger only if necessary. $\endgroup$ Sep 29, 2020 at 4:37
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    $\begingroup$ I don't think drone motors will be a appropriate for this task. If the nub is a vibrator it might be ok, but if it's just rotating you're going to want a gearmotor. Drone motors are designed to spin at thousands of RPMS. $\endgroup$
    – Drew
    Oct 29, 2020 at 8:03

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