Acceleration to Displacement - Filtering Issue
Acceleration to Displacement - Filtering Issue
(OP)
I am using fast fourier transforms to convert raw acceleration to displacement. I am able to get extremely close to expected results; however, I am having issues at the beginning of the dataset. I believe there may be an issue with the filter I am using.
Here is the code for the butterworth filter I am using
I apply it to the raw data and after conversion.
Here are the results, I move the device +/- 10cm, +/- 7.5cm, and +/- 5cm as seen. The green line represents actual movement and the blue line represents the dataset produced through the conversion algorithm.

Any suggestions for better filtering techniques? I can provide the code and some data upon request.
Here is the code for the butterworth filter I am using
CODE --> Matlab
[B,A] = butter(5,0.5/(Fs/2),'high');
I apply it to the raw data and after conversion.
Here are the results, I move the device +/- 10cm, +/- 7.5cm, and +/- 5cm as seen. The green line represents actual movement and the blue line represents the dataset produced through the conversion algorithm.

Any suggestions for better filtering techniques? I can provide the code and some data upon request.





RE: Acceleration to Displacement - Filtering Issue
CODE --> Matlab
RE: Acceleration to Displacement - Filtering Issue
TTFN
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RE: Acceleration to Displacement - Filtering Issue
Whenever you use a high-pass filter there will be some magnitude and phase warp. The warp or "lag" is frequency dependent. Consequently, the estimated displacement is just that, an estimate. You can predict how different the actual from estimated will be by several methods. Firstly, look at a bode plot of the filter input-outputs.
It is evident from your pic that this is what is happening. First easy thing to try is increase the cutt-off frequency of your butterworth filter.
Fe (IronX32)
RE: Acceleration to Displacement - Filtering Issue
RE: Acceleration to Displacement - Filtering Issue
Cheers
Greg Locock
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RE: Acceleration to Displacement - Filtering Issue
Fe (IronX32)
RE: Acceleration to Displacement - Filtering Issue
TTFN
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FAQ731-376: Eng-Tips.com Forum Policies
RE: Acceleration to Displacement - Filtering Issue
M
--
Dr Michael F Platten
RE: Acceleration to Displacement - Filtering Issue
agree with gL, a low pass filter might be more suited to your problem
RE: Acceleration to Displacement - Filtering Issue
Fe (IronX32)
RE: Acceleration to Displacement - Filtering Issue
Ta
M
--
Dr Michael F Platten
RE: Acceleration to Displacement - Filtering Issue
Fe (IronX32)
RE: Acceleration to Displacement - Filtering Issue