Raspberry Pi camera interference near motors?

Has anybody experienced any electromagnetic interference issues or image artifacts on a Raspberry Pi camera mounted in proximity to a Falcon, Neo, or other high power motor?

Our team is considering separating the LEDs and camera from the RPi acting as a vision coprocessor with a longer than usual ribbon cable (probably 8-12 in). The camera would be about 2-4 inches from a pair of Falcon 500’s running the flywheels. It’ll also have a ring of green LEDs around it.

We’ll try to keep the ribbon cable away from the Falcons’ 12V cables.

Not with any of those motors, but some of the noisier power supplies I’ve used on printers have made them unhappy from a few inches away. Sometimes decreased quality, other times no picture. Aluminum foil tape with a proper ground connection took care of it though. I think that was a V1 camera?

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When people talk of solutions like this, I always wonder, our robots do not actually have a ground, correct? If so, does wiring to neutral work? I could be totally wrong here. But, it would be nice to know either way.

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Just learned that the ribbon cable will probably have to run very close to two 775Pros.

I suspect that brushed motors would create more noise than brushless, is that a safe assumption?

Yes, the brushes on brushed motors create a ton of noise across the frequency spectrum.

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Enough to cause signal disruptions for a camera?

I don’t know too much about electromagnetism if you can’t tell.

Just to confirm… have you ruled out that the camera artifacts aren’t a combination of mechanical vibration and the rolling shutter? Asking only because that’s an issue we ran into in 2020.

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Theoretically, maybe. The very best way for you to learn if such interference will occur is to actually_try_it. See what happens. Warning: Learning May Occur.

Electromagnetic interference has two components, electricity and magnetism. Shielding electrical waves requires a conductor of electricity; the aforementioned aluminum ‘shielding’ attached to the chassis at one end only will do. Shielding magnetic waves requires a conductor of magnetism; steel works pretty well, aluminum and copper do not. If the motor is made of steel, well, you’re probably good. Most EMI is electrical.

The frequency of the interference (as well as its magnitude) is important. A low-enough frequency won’t cause interference. Consider as a thought experiment ‘what is the highest frequency generated by this motor (or whatever)’. Don’t guess, either get the specs or research what is typical for motors of they type and technology being used.

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Well, right now this is a hypothetical situation, but our shooter does produce significant vibration and I’ll keep that in mind if I notice any wobbling on the image.

Very good point there. I’ll share what happens when we give it a shot.

Mark,
Ribbon cable has no shielding so any outside interference can have an effect. While brushed DC motors produce significant high frequency energy due to the brushes arcing, brushless motors also can produce significant interference in other ways.
These “spikes” of voltage add noise to the digital system that is often interpreted as video signals. There is shield products available for ribbon cable and there is shielded ribbon cable that is also available. Check Digikey for some of these products. There are also twisted pair ribbon cables that might also reduce interference without shielding. Your best result may be putting the Pi and the camera in a steel box. That would reduce any interference between the camera and the Pi to a minimum.
While it is true that no ‘ground’ exists on the robot, a shield tied to the robot frame at one end (see above) would drain some of the interfering signal to the frame and away from more sensitive components.
And I would be remiss not to mention that the robot rules (most recent version 2021 R8-m) state “high intensity light sources used on the Robot (e.g. super bright LED sources marketed as ‘military grade’ or ‘self-defense’) may only be illuminated for a brief time while targeting and may need to be shrouded to prevent any exposure to participants.”

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