ac servo motor noises, pops, knocks, :)

[damunk]

AC Servo motor noise in speed control mode.

I have like a jittering knock noise coming from the motor. There is nothing wrong with the motor as it is new.

It seems to do it when the speed control is around 0v-1v trying to sit in position or very slight movement, it's like a pop pop ta ta ta. lol

When the motors speeding up and down it's perfectly sound. seems to do it when trying to sit in position or very slow , short distance.

is there some parameters that can be used to smooth things out.

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[Al_The_Man]

What ever system you are using, I would say it sounds like the PID tuning is off IMO.
Al.

[Bdrangdo]

AC Servo motor noise in speed control mode.

I have like a jittering knock noise coming from the motor. There is nothing wrong with the motor as it is new.

It seems to do it when the speed control is around 0v-1v trying to sit in position or very slight movement, it's like a pop pop ta ta ta. lol



When the motors speeding up and down it's perfectly sound. seems to do it when trying to sit in position or very slow , short distance.
is there some parameters that can be used to smooth things out.

Try increasing the dead band and see if that helps.

Sometimes ballscrew or thrust bearing backlash can inducing hunting/oscillation, even more so if the positional feedback is from linear scales.How is the motor connected to the drive system, maybe there is some backlash in the couplings Dave

[damunk]

What ever system you are using, I would say it sounds like the PID tuning is off IMO.
Al.

thanks AL, i will adjust pid tuning.

@ bd rangdo. how to do dead band? are you talking about cut off frequency parameter?


I managed to quieten it down by around 70% by increasing the acc/deleration parameter time slightly.


Can i ask you both, mechanically what is happening in that motor when you hear those kind of noise and is it really inducing extra wear and tear?

[Bdrangdo]

thanks AL, i will adjust pid tuning.

@ bd rangdo. how to do dead band? are you talking about cut off frequency parameter?


I managed to quieten it down by around 70% by increasing the acc/deleration parameter time slightly.


Can i ask you both, mechanically what is happening in that motor when you hear those kind of noise and is it really inducing extra wear and tear?

I don't know what control you are using, each one is different, the "dead band" is an imaginary position that the control considers to the correct position and the servo becomes unpowered. If the dead band is set too small or does not exist the motor can start to resonate, ie the shaft will torsionally vibrate as the motor try's to reach its correct position. Widening the dead band makes the "correct" position easier to achieve but is obviously a compromise. The bigger the dead band the lower the accuracy as it will contribute to the following error. Yes it can produce wear or increase the wear that may preexist. If there is backlash or a lack of machine rigidity, the motor can momentarily over react as it over comes the backlash causing a click or knock as it reaches the load, this in turn can actually knock the slide way to the other end of the backlash, and so it goes on causing vibration whose frequency will depend on various factors. Sometimes it will be a humming sound or much lower in frequency when you can hear each knock or click. each control manufacturer use its own terminology. "Dead band" is a generic term and may be given a different name. The PID filter settings P (proportional gain) I (integer) D (derivative) also can confusingly have different names, again control dependent. You need a manual to figure out the terminology. Dave
I

[AnnArborNate]

I don't know what control you are using, each one is different, the "dead band" is an imaginary position that the control considers to the correct position and the servo becomes unpowered. If the dead band is set too small or does not exist the motor can start to resonate, ie the shaft will torsionally vibrate as the motor try's to reach its correct position. Widening the dead band makes the "correct" position easier to achieve but is obviously a compromise. The bigger the dead band the lower the accuracy as it will contribute to the following error. Yes it can produce wear or increase the wear that may preexist. If there is backlash or a lack of machine rigidity, the motor can momentarily over react as it over comes the backlash causing a click or knock as it reaches the load, this in turn can actually knock the slide way to the other end of the backlash, and so it goes on causing vibration whose frequency will depend on various factors. Sometimes it will be a humming sound or much lower in frequency when you can hear each knock or click. each control manufacturer use its own terminology. "Dead band" is a generic term and may be given a different name. The PID filter settings P (proportional gain) I (integer) D (derivative) also can confusingly have different names, again control dependent. You need a manual to figure out the terminology. Dave
I

That was some Damn Fine information. I dont know servos yet, but am working on it, and this info is awesome. so well explained. Good friday to you Sir, this is wjhat the interned is supposed to be.

[cncmakers001]

AC Servo motor noise in speed control mode.

I have like a jittering knock noise coming from the motor. There is nothing wrong with the motor as it is new.

It seems to do it when the speed control is around 0v-1v trying to sit in position or very slight movement, it's like a pop pop ta ta ta. lol

When the motors speeding up and down it's perfectly sound. seems to do it when trying to sit in position or very slow , short distance.

is there some parameters that can be used to smooth things out.

What are the model names of the motor and driver?

[mactec54]

AC Servo motor noise in speed control mode.

I have like a jittering knock noise coming from the motor. There is nothing wrong with the motor as it is new.

It seems to do it when the speed control is around 0v-1v trying to sit in position or very slight movement, it's like a pop pop ta ta ta. lol

When the motors speeding up and down it's perfectly sound. seems to do it when trying to sit in position or very slow , short distance.

is there some parameters that can be used to smooth things out.

When you say you are using speed control, what control are you using, for the +/- 10v, does your machine have any backlash

[mactec54]

thanks AL, i will adjust pid tuning.

@ bd rangdo. how to do dead band? are you talking about cut off frequency parameter?


I managed to quieten it down by around 70% by increasing the acc/deleration parameter time slightly.


Can i ask you both, mechanically what is happening in that motor when you hear those kind of noise and is it really inducing extra wear and tear?

What is a dead band, you don't have a dead band, there is no such thing with Ac servo's

What is happening is the encoder is trying to find position and it is causing the motor to jump back and forward, if it is to severe then yes it can damage the motor

Lower the Gain and see if that helps

You may have poor quality servo drives, control problems or backlash in your machine

[Bdrangdo]

What is a dead band, you don't have a dead band, there is no such thing with Ac servo's

What is happening is the encoder is trying to find position and it is causing the motor to jump back and forward, if it is to severe then yes it can damage the motor

Lower the Gain and see if that helps
You may have poor quality servo drives, control problems or backlash in your machine

The "dead band" I am referring to is a general term we use in the UK that is a parameter setting in the axis control parameters, maybe you uses a different term in the US. It determines the number of encoder pulses either side of the desired position that the control considers to be correct. Often this can be zero without problems but can be increased to prevent oscillation/hunting if there is backlash or flexing between the motor and the encoder. We do not know what the motors are, or how the encoders are driven, maybe the OP is using scales which can cause problems if there is some backlash, there a lot of unknowns here.

[mactec54]

The "dead band" I am referring to is a general term we use in the UK that is a parameter setting in the axis control parameters, maybe you uses a different term in the US. It determines the number of encoder pulses either side of the desired position that the control considers to be correct. Often this can be zero without problems but can be increased to prevent oscillation/hunting if there is backlash or flexing between the motor and the encoder. We do not know what the motors are, or how the encoders are driven, maybe the OP is using scales which can cause problems if there is some backlash, there a lot of unknowns here.

The OP posted he has AC servos, they have the encoder in one place, which is mounted on the motor, whether he has something else he will have to post the spec's, there is no backlash between the motor and encoder with Ac servos, what type he has yet to be determined

Dead bands where /are common with DC servos, and in the RC hobby world with low count encoders, but not with AC servos even low quality units don't have this problem, oscillation /hunting yes, from incorrect tuning or backlash, it does not matter what country you are from the symptoms and terminology that is used are the same

Ac servo's never become unpowered when it is on position as you posted, or is this meant to mean something else also

[Bdrangdo]

The OP posted he has AC servos, they have the encoder in one place, which is mounted on the motor, whether he has something else he will have to post the spec's, there is no backlash between the motor and encoder with Ac servos, what type he has yet to be determined

Dead bands where /are common with DC servos, and in the RC hobby world with low count encoders, but not with AC servos even low quality units don't have this problem, oscillation /hunting yes, from incorrect tuning or backlash, it does not matter what country you are from the symptoms and terminology that is used are the same

Ac servo's never become unpowered when it is on position as you posted, or is this meant to mean something else also

I need to get my eyes tested, or learn to read, I missed the reference to an AC motor.
I