Many times with steppers, if the sound seems to go away, it didn't. You only move the frequency to a range your ears can't detect. Remember that the sound is likely not a primary frequency but maybe a harmonic or "beat" frequency and those would move unpredictable, or at least unintuitively.
I'm trying to think how a PID P gain can affect noise. Typically, the way to get the P gain is to make it better until the system oscillates, then back down some. Very unscientific but this works, With the high P-value I wonder if noise was from the oscillation. Sound from motors is hard to predict. Some times it is obvious like a 1KHz step making a 1Khz tone. But it might be the pulse edge interacting with the motor housing. Some years ago, believe it or not, in the days when we would build motor drivers ourselves, I had a motor that sounded like an AM radio talk show. I could hear most of the words. The motor ran correctly at different speeds but my controller placed an audio signal on top of the DC so in this case, the sound was nothing to do with software setting. I had built an AM radio by accident. On Tue, Feb 1, 2022 at 11:44 PM Thaddeus Waldner <thadw...@gmail.com> wrote: > Hi, > > I have a pi4 running the 2.8.2 iso. I have it connected to a Mesa 7i96 and > from there I’m driving small stepper motors with tmc2209 “stepstick” > drivers. I think my step rate at max speed is around 8khz > > I get around +-70us? Max latency. > > I’ve been having an issue with what I think is latency which makes the > steppers sound like they have bad bearings. Raising the servo period to 2ms > made it worse. So I tried a faster servo thread and discovered the issue > pretty much goes away with the servo period at 250us. At that rate I start > running into joint following issues. > > I then learned that with the servo period at 1ms, if I lower the stepper > PID P parameter to 100 instead of the 1000 set by the configuration wizard, > the noise goes away completely and the steppers run buttery smooth. > > I have a few questions: > 1) what are the implications of running the PID stepper with p=100? > 2) why is servo thread jitter even making into the stepper pulse train > with a Mesa Ethernet card and no communication errors? Do I have anything > misconfigured? > > Thanks > > > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Chris Albertson Redondo Beach, California _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
