Go Down

Topic: Natural error in accelerometer measurements? (Read 845 times) previous topic - next topic

Seán

Hello,

I was speaking with someone over the weekend who was telling me that when you integrate the measurements from an accelerometer, over time, you can get an error in the readings. And, I imagne, given a long enough time, the error will get larger and larger.

I am afriad he wasn't really able to explain why this was so.

Is this correct? And, if it is, what causes it? Also, I guess, is there a way to factor out the error?

Thanks.

Seán
Ná bac le mac an bhacaigh is ní bhacfaidh mac an bhacaigh leat.

johnwasser

If you integrate acceleration over time to get velocity you will also be integrating any offset or other error such as rounding or precision.  Also remember that the readings you are getting are instantaneous values for a continuous process.  The value represents the current acceleration, not the average acceleration sine the last reading so if the acceleration is changing, using the current value as the average for the last time period will introduce errors.

Of course if the accelerometer is not in a fixed orientation relative to the local gravity you can't tell if the acceleration you are reading is due to change in velocity or due to gravity.
Send Bitcoin tips to: 1L3CTDoTgrXNA5WyF77uWqt4gUdye9mezN
Send Litecoin tips to : LVtpaq6JgJAZwvnVq3ftVeHafWkcpmuR1e

Seán

Ah yes, of course, that makes sense! Thanks.

So, is there any way to avoid these errors, or at least, limit their effects? I assume using as accurate a number as possible for acceleration will help.

Seán
Ná bac le mac an bhacaigh is ní bhacfaidh mac an bhacaigh leat.

johnwasser

Certainly having as much accuracy and precision as you can get will help.  You can try characterizing the errors and calculating the accumulated error so you can correct for it.  What is it you are trying to find the velocity of?  Perhaps there is a different sensor that will work better.
Send Bitcoin tips to: 1L3CTDoTgrXNA5WyF77uWqt4gUdye9mezN
Send Litecoin tips to : LVtpaq6JgJAZwvnVq3ftVeHafWkcpmuR1e

Seán

Hey,

Thanks for the replies!

It will mainly be walking speeds. Nothing too fast.

I was wondering was there some sort of common mode rejection system.

Seán
Ná bac le mac an bhacaigh is ní bhacfaidh mac an bhacaigh leat.

Go Up