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acceleration to displacement

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The centre plot is having a meanline ZERO (and not -0.159). Its peak-peak is -0.159 tp +0.159.

Moreover the centre plot is just like a pure cos signal. So its integral should be like a sine signal AND THAT SINE SIGNAL IS NOT EXPECTED TO DRIFT DOWNWARDS.

 

Please correct me ...where am I wrong?

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Message 11 of 34
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Hi Sehgal,

 

you added those "-0.159" to your "cos"-plot. So it has a mean of -0.159!

Best regards,
GerdW


using LV2016/2019/2021 on Win10/11+cRIO, TestStand2016/2019
Message 12 of 34
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Sehgal wrote: AND THAT SINE SIGNAL IS NOT EXPECTED TO DRIFT DOWNWARDS.


Do not shout, I don't like it.Smiley Mad

Thoric (CLA, CLED, CTD and LabVIEW Champion)


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Message 13 of 34
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Okay ...take it easy....Actually those captial letter were not meant for shouting

Anyways I am sorry for that

 

Please tell me how to condition that drifting sine signal so that it becomes a pure sine signal with no drift

 

 

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Message 14 of 34
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Hi Sehgal,

 

don't add an offset to your "cos" signal...

Best regards,
GerdW


using LV2016/2019/2021 on Win10/11+cRIO, TestStand2016/2019
Message 15 of 34
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What Gerd said.

Thoric (CLA, CLED, CTD and LabVIEW Champion)


Message 16 of 34
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Solution
Accepted by topic author Sehgal

Here you have taken accelaration as a sine wave. a = A sin(wt)

 

On Integrating from t=0 to t='t' you get the wave as v = -(A/w) cos(wt) + (A/w)

 

On further integrating this, a shift is experienced from a natural sinusoidal wave due to the (A/w) constant.

 

To get rid of that you need to subtract an equal amount of A/w.

 

What you did was subtract 0.15... which just an approximation ( A / 2*pi*f )and hence a shift is observed. Instead subtract the actual value.

 

I have employed the same in the attachment and it seems to be working fine. Try playing around with different values of amplitude and frequency which would have affected your vi but wont affect this vi.

-Avichal (C.L.A.D)
(AE, NI India)
Message 17 of 34
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Thanks a lot. The problem got solved. 

I am feeling so happy and relieved now while using Labview.

 

Heartiest Thanks !!!!!!!!!!!!!!!!!!!

Message 18 of 34
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Hi AvichalK,

 

is this method applicable to acceleration coming from ADXL345 Accelerometer? I also need the displacement but I only have the acceleration.

 

Can I just exactly integrate your method to my VI?

 

Thank you!

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Message 19 of 34
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Hi all

 

Sorry to recover this topic, but I have a similar problem.

I would like to get a displacement from an accelerometer pulse.

I have the MMA7260Q  ±1.5g - 6g Three Axis Low-g Micromachined Accelerometer.

I only read the zz channel with ni usb 6009. As I power it with 2.5v with the accelerometer side up I get 1.4 volts, and side down 1.1volts in zz.So it has a 150mv/g.  I am using 6g resolution. 

I had tryed with the example in attach the accelerometr on my desk and with a hand pulse I expect (in microns) a value near 1000micros, but the value are too lower.

 

I tryed many times with double integration, but I have the same problem, displacement never stabilize, because the noise.

 

Thanks for any help

 

cpalka

 

 

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Message 20 of 34
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