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Generally, I'm interested in simple (DIY) electric vehicle design problems. I saw some photos of electric vehicles as in the following pic:

4dw diy vehicle

or also you could check this youtube video.

The vehicle is using an independent wheel drive, so it has 4 bicycle hub motors - one for each wheel. How is possible to regulate/sync the motor's RPM/torque in the turns? In the classic one-motor design this is solved by using a differential but how it is solved in an independent wheel drive scenario?

I am also wondering what happens when one wheel temporarily leaves the ground (e.g. in some off-road scenario). Wouldn't it start spinning very fast in the air, without contact with a surface?

As a programmer, I could imagine some Arduino-based "software differential" for the front wheels, which will regulate the RPM on the wheels based on the "steering wheel" angle, but I don't know how to do the same on the rear wheels.

Also, using an Arduino in such projects doesn't sound very "bullet-proof" but a car, especially such an important thing as engine RPM/torque regulation, needs to be "bulletproof" even as a DIY project, so I am not convinced that this would be a reasonable solution.

How it is possible to solve the independent wheel drive problems in the simple DIY world?

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  • $\begingroup$ Some trigonometry, with knowledge of rolling radius, slippage etc $\endgroup$
    – Solar Mike
    Commented Apr 20, 2018 at 11:26
  • $\begingroup$ @SolarMike "that trick never works" . I'd recommend strain gauges of some sort with feedback to a global controller which adjusts all 4 motors' drive current until all 4 wheels are at the same strain level. Then add a bunch of "except if" for loss of traction, ... and so on. $\endgroup$ Commented Apr 20, 2018 at 14:23
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    $\begingroup$ Just found: arxiv.org/pdf/1803.09411.pdf I thought it could be done "easier", but looks that it really needs some complicated math. The 14DOF model is mind-killer. :( $\endgroup$
    – clt60
    Commented Apr 20, 2018 at 15:50
  • $\begingroup$ After many hours of browsing I got some ideas = basically, this question is "too broad". :( I leave the question here - maybe someone could post one big answer with some github-link :), but it really needs to pay attention to many many things - even in the simple DIY (or RC) world. $\endgroup$
    – clt60
    Commented Apr 20, 2018 at 18:30
  • $\begingroup$ Hm.. anyone should read this trike build. Even if it is for the 2WD trike, it is an simple solution and it just works. (of course, not "scientifically" correct) :D :). Also found a funny cite: There have always been "experts" that fretted about the lack of a "differential" etc., but even a fairly powerful two wheel pusher trailer never had any adverse affect on a two wheel bike during cornering. $\endgroup$
    – clt60
    Commented Apr 22, 2018 at 21:26

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Why not consider using an individual Wheel Speed Sensor signal input into an algorithm for wheel speed equalization to prevent wheel spin just as in ABS Brakes applications and other 4WD scenarios.

Chidi Okonkwo

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  • $\begingroup$ As it’s currently written, your answer is unclear. Please edit to add additional details that will help others understand how this addresses the question asked. You can find more information on how to write good answers in the help center. $\endgroup$
    – Community Bot
    Commented May 18 at 20:17

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