Hello fellow makers, I’d like to ask you for some directions regarding my somewhat unstable (yet repeating) chart of motor rpm. On picture, you can clearly see two periods of registered rotations, which are supposed to be around 33 and 1/3 rpm, but instead I get a floaty pattern, which can be also faintly heard in high pitch whisper coming from the motor.
I was tasked to create a replacement engine for a turntable (gramophone). My initial thought was to get a gimbal motor (as I need smoothness above all in driving turntable and gimbals are know for their smooth movement) and I was really pumped up to find a simpleFOC library, that I can simply load into arduino and bam work done. Sadly, even if programming procedure was easy enough, I cannot get a smooth motion.
I am using: GM5208-24 blcd gimbal motor, simpleFOCShield v3.2, AS5048 magnetic encoder and ESP32 Dev Module (which I program in Arduino IDE).
I expect the tiny fluctuations visible on the chart to be cogging torque ripple (which I for now have not enough skill to tackle), but the bigger oscilations clearly stems from some motion control problem and I was hoping for either some directions, what could I investigate to get rid of them or a definitive info that it is somehow an intristic feature of my setup and therefore not solvable without changing some parts of it.
I did a fair bit of PI(D) tuning/tinkering (Q current/D current/velocity), but I could not find the setting that would get rid of these slow oscillations.
My code: gramophonEngine - Pastebin.com