acceleration to displacement

[MicheleC.]

I'am sorry, I'am working on something similar, and I can't use the file "improved_integration.... " becouse there are something wrong when I  try to open it.

Can you repost the file or something similar project?

I use LV 2016.

thanks

best regards

Michele

[AvichalK]

Uploaded for LV 16

[cpalka]

My friends

I still not have a good displacement from a tripple accele...

The best explanation that i found sinve today is in this video...I will try to implement it and see the results...

https://www.youtube.com/watch?v=FnYSydDqY74

Best

cpalka

[cpalka]

Almost there

But comparing with a real system, it stills give wrong values...near but need to improove.

cpalka

[cpalka]

Hi friends

After some time and I stiil not have the acceleration to displacement well calculated...

My hardware now is:

NI9233 + Ni USB 9162

I try with

an accelerometer and double integration

https://www.mmf.de/pdf/1-7-2.pdf     (KS901B10)

and a geophone and simple integration

https://www.iongeo.com/content/documents/Resource%20Center/Brochures%20and%20Data%20Sheets/Data%20Sh...  (4.5Hz)

After testind many examples, even with module from noise and vibration A-V-D vi

Is this board appropriate for readind this sensors???

This 2 sensors are from a comercial equipement that applyes a load pulse on the ground and this sensors measure the ground deformation.

In the equipemtns the sensors measures good values but with LB and this board...I still have not good results....

Best regards

cpalka

[Henrik_Volkers]

The 9233 is a IEPE sensor only device, so your Metra sensor fit.

For the geophone coil you need an adaption. Here is a schematic how I would give it a try:

R1 and C1 cut of the IEPE current and R1 is also the damping resistor for the coil.

For integration: If you have the sound and vibration module, try the integration module, it offers an additional high pass filters to cut offsets.

[Henrik_Volkers]

Some more hints after looking into the spec :

After integration you can add a high pass filter at about 0.5Hz since the 9233 has one build in anyway.

And to meet the common voltage range you maybe need to add another resistor R2 ... the R1 is for the coil damping but only give ~4V bias so your measurement range is only +-4V instead of +-5V , with R2 bias is ~8V.

[cpalka]

Hi Henrik

Many thanks for the explanation.

Before answear I would like to teel you what I made in last days.

Finnaly I have some success:

- with noise and vibration module

- correct X scale in the graphs to see the deformation curve

- I need to respect the polarity ( I though this could be changed...)

- for the accel I use the sensitivity 10mv/g as in datasheet and it gives good results

- for geophone I need to adjust, instead 28V/m/s I use 22V/m/s (maybe with your circuit suggestion it works fine with 28)

- the commercial equipment uses the accelerometer and I use this results to compare with my VIs.

In attach are the first version of vis for the accel and geoph and some printscreens, it uses the A-V-D vi from noise and vibration, i let 1 for the filter, I add a trigger to get the deformation when it is greater than 0.2mm (negative) and I have deformations after a load pulse of about 0.5mm to 1.5mm.

About noise, it is very high when we use the pc connected to the charger, better work only with battery...

So, if I build the circuit do You think that the geophone will accept the 28V/m/s ?

Once again many thanks

cpalka 

[Henrik_Volkers]

>So, if I build the circuit do You think that the geophone will accept the 28V/m/s ?

Well, with a direct connection to the 2 mA IEPE input you preload the internal spring loaded coil (and the seismic mass) with a current -> force -> higher stiffness  ... so yes, I would expect a reduced sensitivity  ...

If you don't have a calibration sheet for your IEPE sensor (maybe Metra have a copy?) and you have a vertical shaker, you can make a coarse sensitivity check (others may call it a calibration together with a MUB ;)) : Place a steel ball (or nut) (Stainless steel or brass if magnec fields from the shaker are a concern) near or on the sensor. Apply a sine and slowly increase the amplitude. If you reach and pass 1 g_local the ball(nut) starts to lift of and that point can easely be spotted monitoring the sensor output on a scope (or FFT or ..)

Now you can mount and compare both sensors on your shaker.

[cpalka]

Hi Henrik

Today I make some measurements with and without your circuit compared with comercial equipement.

1 - without circuit and sensitivity 22V/m/s

comercial deformation: 0.983mm; 0.983mm; 0.982mm

Geophone: 0.777mm; 0.768mm; 0.764mm

2- with electronic circuit  and sensi 22V/m/s

Comercial: the same

Geophone: 0.718; 0.716; 0.721

3- with electronic circuit  and sensi 28V/m/s (in datasheet)

Comercial: the same

Geophone: 0.563; 0.567; 0.566

4- with electronic circuit (1st circuit only 1 R 2K ohm)  and sensi 28V/m/s

Comercial: the same

Geophone: 0.568; 0.569; 0.578

Conclusion:

I expect the deformation will increase with circuit, but decreases

Using first circuit or secound one, seems no difference.

Best regards

cpalka