# Compensating for Accelerometer Misalignment

1. Jul 9, 2010

### IMK

Hello
I am developing a programme in C that uses a Tri Axial Accelerometer and I have become bogged down with the maths for correcting cross axis misalignment errors and was wondering if someone could help me please.

I have two papers on the subject and I have worked my way through the axis offset and scaling. But I am finding this matrix inversion and transposition more than a handful.

The papers are to be found here:

This one is the general math
http://www.summitinstruments.com/knowledge_center/pdf/TN413.pdf

This one is to an application note from the manufacture of the device I am
using (or similar)

http://www.st.com/stonline/products/literature/an/17289.pdf [Broken]

From Page 9 on is the alignment error correction stuff.
I have created a Table 2 and written the software to do Equation 1 (I think it is correct). I have managed to write a Matrix Inversion function that I think is correct as I have compared it with the Determinant and Inverted Output from the Online Matrix calculator here; http://www.bluebit.gr/matrix-calculator/

But now I am stuck, help would really be appreciated.

Many thanks in advance.

Last edited by a moderator: May 4, 2017
2. Oct 6, 2014

### Sam Smith

I am having a similar problem however I am unable to access the papers you have posted. The way I have approach this one is by working out inital roll pitch and yaw using the following;

roll = arcsin(Xval/1)
pitch = arcsin(Yval/1)
yaw = arcos(1/Zval)

I then input these into rotation matrix in mathlab. However this does not quite give correct result. Am still working with this problem