Sensors中的主题 Re: Tilt correction matrix in accelerometer calibration

Tilt correction matrix in accelerometer calibration

j_perezdelarray — Tue, 03 Feb 2026 21:47:12 GMT

Hello,

The tilt correction matrix is a rotation matrix to align the pitch and roll angles to the perpendicular plane of gravity so it can be considered as a change of basis or alignment matrix if, for example, the sensor frame is not aligned with the body frame.

I haven't been able to find in the sensor fusion documentation "when" and "where" in the filter this rotation matrix is computed. Does anybody have the answer?

thank you,

Re: Tilt correction matrix in accelerometer calibration

shubhadippaul-b — Tue, 15 May 2018 22:27:08 GMT

Hi,

Please refer to Chapter 3 of Application Note AN4246 available @NXP - Calibrating an eCompass.

The NXP SF Algorithm is based on the method described in the document.

Re: Tilt correction matrix in accelerometer calibration

j_perezdelarray — Tue, 15 May 2018 22:36:58 GMT

Hi Paul,

Thanks for your reply. I'm referring to the tilt compensation matrix in the calibration tab. It's not related to the compass

Re: Tilt correction matrix in accelerometer calibration

shubhadippaul-b — Tue, 15 May 2018 23:21:33 GMT

Hi,

Can you please elaborate and send a snapshot of the Calibration Tab you are referring to?
In NXP SF GUI, the calibration Tab only has options to write and erase calibration parameters to and from FLASH.

I hope your have already referred to Chapter 4 of Application Note AN4248 available @ NXP - Implementing a Tilt-Compensated. Though the documents talk about eCompass (Accelerometer + Magmetometer), you may find the equations for Accelerometer useful.

Now if you are simply looking for mounting offset correction - correction of offsets due to Plane of Sensor not being aligned to gravitational plane, please refer to AN4399 available @ NXP - High-Precision Calibration of a Three-Axis Accelerometer. This offset is corrected in the Accelerometer counts output before using it for SF Algorithms.

Re: Tilt correction matrix in accelerometer calibration

j_perezdelarray — Wed, 16 May 2018 10:42:46 GMT

I'm referring to the "0 flat" button in the "Precision Accelerometer" tab. The funtion of this button is described in section 4 of document AN5021 (Accelrometer tilt orientation matrix). When pressing this button, a tilt correction matrix is stored in memory and applied to orientation data. I would like to know when is this tilt correction matrix applied in the filter.

thank you,

Re: Tilt correction matrix in accelerometer calibration

shubhadippaul-b — Wed, 16 May 2018 18:19:53 GMT

Hi,

Precision Accelerometer Calibration compensates for mounting offsets - correction of offsets due to Plane of Sensor not being aligned to gravitational plane, for details you may refer to chapter 7 in AN4399 available @ NXP - High-Precision Calibration of a Three-Axis Accelerometer.

In the SF Application, the sequence of steps involved to apply Precision Accelerometer Calibration to Accelerometer Measurements is as follows:

First, using the Precision Accelerometer tab, 12 point accelerometer data measurements can be carried out and used to compute Calibration parameters.
Then, using options form Menu item Calibration, the computed calibration parameters can be written to the MCU board Flash.
Subsequently, from the next board reset, the written parameters are read and used by the SF Application.
The Calibration parameters are applied to every new accelerometer measurements after it is acquired. This is done inside the processAccelData() function in sensor_fusion.c file in the SF code.
The resulting measurement is then used in all Filter Algorithms by the SF Application.