Phase Shift Correction?

[alexgieg]

I'm measuring an actuator response signal as well as the displacement of the test unit with LVDTs. The LVDTs signals are filtered, the actuator response isn't, what causes the actuator signal to have a different phase from that of the LVDTs. Is there a way in DASYLab (v11) to cause the actuator signal to be automatically shifted so that its signal can be visualized aligned with the ones from the LVDTs?

Thanks!

[TomRizzo]

Is the actuator response signal also form an LVDT?  What kind of frequnecy are you running?

Is the signal from the Actutor coming back from a Servo controller like MTS?

Also, what is the phase shift?

[alexgieg]

The actuator response is a 0-10V signal. It comes as an already conditioned 0 to +10V signal, and very clean, so I measure it on a simple voltage input channel.

Frequencies are low, in the 0-50 Hz range. Since we measure harmonics our acquisition rate is usually 500Hz for dynamic signals.

Yes, it comes back from a servo controller.

The phase shift varies with the frequency. If we're measuring something slow, let's say, at 2 Hz, it's barely noticeable. As the frequency increases it becomes more and more so until it reaches 180 degrees and switches to -180. The impression I have, although I haven't measured it, is that the actual "distance" on the X axis between the two signals remains basically constant, so a higher frequency / shorter cycle causes this same distance to "mean" proportionally more and more in terms of degrees.

PS.: Sorry if I'm not using the precise terms. I'm not quite sure how to phrase them in English.