From: Vladimir Vassilevsky on


haoxiang wrote:

> I am working on a project on human static standing and i am measuring
> the angular body sway of a human when he/she is standing still.

What is a purpose of that?

> I am using
> a tri-axis accelerometer
> (http://www.sparkfun.com/commerce/product_info.php?products_id=8563) and
> obtaining angular displacement estimate based on double integration of
> acceleration reading and some least-square estimates. Unfortunately my
> experiment duration need to be at least 1 minute and the drift error causes
> the estimate to be way off the mark... It doesn't help that i can't exactly
> pinpoint my initial acceleration.
>
> Can anyone suggest any method to reduce the error in my measurement? My
> prof suggested calibrating the result which another camera system which
> simultaneously track position but as time is tight, i would hope to find
> solution based solely on accelerometer and parameters i have.... Hope to
> hear good news soon

The accuracy of MEMS accelerometers is inadequate for innertial
measurements. However, you can measure tilt angle with respect to
gravitation and figure out the sway from there.


Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com
From: Richard Owlett on
Vladimir Vassilevsky wrote:
>
>
> haoxiang wrote:
>
>> I am working on a project on human static standing and i am measuring
>> the angular body sway of a human when he/she is standing still.
>
> What is a purpose of that?
>

Probably because it was a lab assignment.
Also could be quite useful in physical therapy. I've been there -
my current Berg Balance score is ~25.

BTW the chip manufacturer has an app note for a related
application. I'll have to wait to get to a high speed connection
to download and read it.
From: Richard Owlett on
How did the project come out?


haoxiang wrote:
> Hi all,
>
> I am working on a project on human static standing and i am measuring
> the angular body sway of a human when he/she is standing still. I am using
> a tri-axis accelerometer
> (http://www.sparkfun.com/commerce/product_info.php?products_id=8563) and
> obtaining angular displacement estimate based on double integration of
> acceleration reading and some least-square estimates. Unfortunately my
> experiment duration need to be at least 1 minute and the drift error causes
> the estimate to be way off the mark... It doesn't help that i can't exactly
> pinpoint my initial acceleration.
>
> Can anyone suggest any method to reduce the error in my measurement? My
> prof suggested calibrating the result which another camera system which
> simultaneously track position but as time is tight, i would hope to find
> solution based solely on accelerometer and parameters i have.... Hope to
> hear good news soon
>
> Regards,
> Hao Xiang
>
>