Encoder Eccentricity Correction

Hi, I’m using ODrive to drive Tmotor U8 as a high torque density actuator, but found out that at a little bit high speed, motor starts vibrate violently. Sometimes the current loop becomes unstable. I thought the U8 motor’s pole pairs is too high (21 pole pairs), with under 10 pole pairs motor no problem at all.

After reading this artical “BuildIts in Progress: Encoder Autocalibration for Brushless Motors: Offset and Eccentricity”. I think the reason cause this problem maybe encoder eccentricity. I’m using a AS5047P as the encoder and ABI interface.

Do you have any plan to solve this problem in the future firmware or any solution for this problem now? @ Wetmelon

Thanks!

Ugh, one of those things that’s “on the roadmap”. It really needs to be done. This datasheet for the A1335 gives a really great overview of the various non-linearities if you want to take a crack at it. https://www.allegromicro.com/~/media/Files/Datasheets/A1335-Datasheet.ashx (PDF Warning)