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Unread 26-12-2014, 12:59
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Re: Best gyro for frc.

Quote:
Originally Posted by ayeckley View Post
Not to bust your chops, but that's true for electric fields -- not so much for magnetic fields. Effective magnetic shielding requires the use of a material with a high magnetic permeability such as Mu-metal (Carpenter Specialty Alloys). Rolled foil copper such as that found on PCBs has little effect.
I don't think you'd need mu-metal to shield because it's a higher frequency magnetic field. The new victors switch at 15 kHz, so copper, aluminum or preferably steel may make an effective shield. That said, if your problem is due to the DC magnetic field from something like the battery cable, copper or aluminum won't do much. However, the DC magnetic field is much weaker than the fields from the motors, which are quite noisy. The motors brushes create lots of really high frequency em fields that can be blocked by copper.

The best way to solve the interference problem is to twist the gyros signal and return cable. The two conductors act like a loop which pick up the magnetic field from your motors. Twisting these two conductors will decrease the effective loop area and greatly reduce the interference. You can prevent common mode interference with a grounded shield on the conductors.

Increasing our switching frequency to 15khz makes interferences problems 15 times worse than the 1khz.