07-23-2012 08:06 AM
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?
07-23-2012 08:08 AM - edited 07-23-2012 08:08 AM
07-23-2012 08:09 AM
07-23-2012 08:17 AM
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
07-23-2012 08:18 AM
07-23-2012 08:49 AM
07-24-2012 09:36 AM
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.
07-24-2012 11:11 PM
Thanks a lot. The problem got solved.
I am feeling so happy and relieved now while using Labview.
Heartiest Thanks !!!!!!!!!!!!!!!!!!!
03-23-2016 10:27 AM
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!
05-21-2017 11:08 AM
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