【FXOS8700cq Yaw angle error!(Eager )】

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【FXOS8700cq Yaw angle error!(Eager )】

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Joz
Contributor I

Hello everyone!

I am currently working on the development of the electronic compass,

Need to be accurate ±1~2°

Refer to Tomas' routine,Thanks Tomas,Add ellipsoid algorithm calibration, but the error is always large,Refer to the picture 1.

My question is, What is the yaw angle error of the 8700cq chip? I read some articles and indicated ±5°,Is it true?

Ellipsoid fitting result:

 

Joz_2-1616142772690.pngJoz_3-1616142799254.png

Actual test data:rotate 45° to record 

Joz_4-1616142816469.png

Looking forward to your reply!

Regards

Joz

 

 

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3 Replies

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JozefKozon
NXP TechSupport
NXP TechSupport

Hello Joz,

It is hard to estimate an accuracy. Many things come into account.

The magnetometer requires calibrating not only for its own offset, but also against spurious magnetic fields resulting from any nearby ferromagnetic components on the circuit board.

App notes discussing this topic in detail:

Calibrating an eCompass in the Presence of Hard- and Soft-Iron Interference

Accuracy of Angle Estimation in eCompass and 3D Pointer Applications

With Best Regards,

Jozef

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84 Views
Joz
Contributor I

Hello Jozef,

Thank you for your reply!

I read your message carefully,

What I want to know is, what is the actual control error limit of the FXOS8700 electronic compass application?

Determine if it applies to my project.

Looking forward to your reply!

Regards

Joz

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60 Views
JozefKozon
NXP TechSupport
NXP TechSupport

Hello Joz,

please see below an answer from an application engineer I have contacted.

DESCRIPTION

The accuracy is  critically dependent on the calibration,  it is expected +/-5 degree with typical calibration result we see, the result accuracy could be better or even worse depending on severity of the magneto interference and calibration completeness.

Is this red circle above after calibration?  It looks there are still some residue hard/soft iron offset, the offset  can be seen  from X axis.  If the offset can be reduced then the accuracy may be increased.

With Best Regards,

Jozef

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