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I am currently in the design phase of a project that is using 3 arduino nanos controlling 2 small stepper motors (28BYJ-48) each. There is a lot of moving parts where some movements are continuous and each arduino is separated from each other by at least one of these continuous parts. This makes it quite difficult since I want to connect the arduinos to each other.

The options I am seeing are:

  • Connecting them via a powered rail and hoping that the contact surface is good enough. There is a risk that my tolerances are too high and I'll lose connection to an arduino. There is also a problem that I need at a minimum of 3 rails(power, ground and data?)

  • Using induction to send power to the arduino. With this method I could probably send data through an RF module.

I think that using induction should be the best solution, but I am not sure as this isn't really my field. So the question is, is it feasible to create a small coil and power the arduinos this way? I am not sure if they would disturb the stepper motors either.

edit

To clarify I have a couple of discs with a diameter of around 20cm, that are pretty much touching eachother so the coils can be quite close and 20cm diameter. The coil thickness can be 5mm without interfering with other components.

The discs are oriented the same way and rotating independently in the z-axis.

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  • \$\begingroup\$ Just add some batteries. \$\endgroup\$ – Eugene Sh. Jun 4 '18 at 14:20
  • \$\begingroup\$ Power induction works or fails on your physical limitations and you have given hardly any details. \$\endgroup\$ – Andy aka Jun 4 '18 at 14:23
  • \$\begingroup\$ @EugeneSh. I hadn't even though about that. But the components are rather difficult to get to and with some space constraints I don't think that I'll be able to get them in \$\endgroup\$ – munHunger Jun 4 '18 at 14:30
  • \$\begingroup\$ Or use a wire harness that flexes with your movement, won't work if you need full rotation, but if you can get away with reversing as needed... \$\endgroup\$ – ratchet freak Jun 4 '18 at 14:33
  • \$\begingroup\$ Yeah, I though about a harness, but it won't work as I want continuous rotation without reversing \$\endgroup\$ – munHunger Jun 4 '18 at 14:38
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To clarify I have a couple of discs with a diameter of around 20cm, that are pretty much touching eachother so the coils can be quite close and 20cm diameter. The coil thickness can be 5mm without interfering with other components.

Based on what you say above I have built rotary transformers that can easily pass a watt or two (more with care and cost of course) from a stator coil to a rotating coil just using PCB coils. Two or three turns is all that is needed but you have to consider the cost even for the minimum system. You have to design a power oscillator (hundreds of kHz) that can drive the stator coil at at a peak voltage in the low tens of volts. These sorts of designs are always more effective if resonant tuned with parallel capacitors.

So you'd have a rotor and stator coil transmitting power and the rotor would also require tuning. The output can feed a "fast" bridge rectifier and then a buck converter to feed the spinning arduino.

Regards data, if you only require data from the spinning device then use an optical link "on axis". Again, this is proven technology. If you require an uplink to the spinning Arduino and this can be slow data then you can AM modulate the power signal and demodulate on the rotor side. Again, proven technology.

If you require fast data in both directions then life becomes harder and you might need to adopt an "around the shaft" technique for data in one direction whilst the other data uses the "on axis" centreline for its data. I have used two concentric coils and an optical link for one job. The outer coils provided power, the inner coils were an uplink FM modulated at 80 MHz and the optical part was the down link.

Or just use good old fashioned slip rings and hope for the best!

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