acceleration integration

[Tenngineer]

Hello,
I am currently working on a project where I need to find a digital integration for acceleration data. I believe I have found a sufficient integration filter that I have tested in matlab but after the first integration there is a dc offset that makes the second integration to get displacement data impossible. It would be ideal to find another type of filter to remove the dc offset for my project. I have tried basic high pass filters with no luck. Is it possible to do such a thing? and if so could someone advise me on a sufficient high pass filter?

 

[GregLocock]

You can remove the DC offset from the signal with just about any correctly calculated HP filter, so I don't know what you are doing wrong.

Anyway, another method is to subtract the straight line joining the dfirst and last points in the integrated data - this is nice from apractical point of view, but is analyitically treacherous.

Or you can remove the average level from the original data.

This is less dangerous.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[electricpete]

Don't forget to perform high-pass filtering (dc offset removal) both before and after integration.

There are many ways to do high pass filtering. A small twist on Greg's method is to subtract a rolling average.

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[GregLocock]

Subtracting a moving average is a very nice way to do it, and is mathematically equivalent to a high pass filter, tho I can't remember which shape it is.

Of course, 5 minutes in MathCad would tell me.



Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[sreid]

Below is one author's recomendation for a high pass filter to remove DC bias. I don't know if there is anything unique about this.

OUT = IN-IN(n-1)+ [alpha x OUT(n-1)]

Where alpha is the decay constant between 0 and 1