How to perform a sine sweep using torque control servo amp
How to perform a sine sweep using torque control servo amp
(OP)
Hi,
I'm trying to figure out how I can characterize the natural modes of my mechanical system. I have a servo amp in which a voltage is fed and in turn a PWM is generated. So the voltage fed is proportional to the torque I want to apply. The feedback is an encoder. However, when I do a sine sweep test I'm really looking at the phase and magnitude difference between the commanded position and actual position.
1) So how do I perform a sine sweep on my system if the commands i'm giving to the servo amp (using only as an amp, not using feedback) is a torque (voltage) and i'm reading the encoder back?
2) I was thinking that I could differentiate the torque signal (just get another sine wave) and infer the commanded position, but I don't know if this is the proper way to do this.
3) are there any texts that go over examples on how to do a sine sweep using different kinds of amplifiers to identify modes of the plant?
thanks,
windell
I'm trying to figure out how I can characterize the natural modes of my mechanical system. I have a servo amp in which a voltage is fed and in turn a PWM is generated. So the voltage fed is proportional to the torque I want to apply. The feedback is an encoder. However, when I do a sine sweep test I'm really looking at the phase and magnitude difference between the commanded position and actual position.
1) So how do I perform a sine sweep on my system if the commands i'm giving to the servo amp (using only as an amp, not using feedback) is a torque (voltage) and i'm reading the encoder back?
2) I was thinking that I could differentiate the torque signal (just get another sine wave) and infer the commanded position, but I don't know if this is the proper way to do this.
3) are there any texts that go over examples on how to do a sine sweep using different kinds of amplifiers to identify modes of the plant?
thanks,
windell





RE: How to perform a sine sweep using torque control servo amp
I recently did a resonance search on an 11 kV 1600 kVA transformer + harmonics filter using a 900 W audio amplifier (that was what we could get hold of in that part of the World) an arbitrary function generator that could output a swept sine and a recorder with FFT analysis. Found a surprising 195 Hz resonance where there shouldn't be any resonance at all.
We didn't need to look at phase angles, but that would certainly also have be possible.
Gunnar Englund
www.gke.org
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Half full - Half empty? I don't mind. It's what in it that counts.
RE: How to perform a sine sweep using torque control servo amp
Google Bode Plot instead.
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: How to perform a sine sweep using torque control servo amp
1) I'm trying to figure out what the best way is to do this and how this is done in industry.
2) Will the bode plot for Accl_out/Accel_in be the same as Pos_out/Pos_in?
RE: How to perform a sine sweep using torque control servo amp
You must define the characters you are interested in though. This is the part I think you don't quit understand.
If you are interested in the position then you are really looking at the amplitude and phase of the fluctuating component of the position.
For example: http://ctms.engin.umich.edu/CTMS/index.php?example...
RE: How to perform a sine sweep using torque control servo amp