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Help with 5883L crazyness.

screamingtiger

 

I have collected data and cannot get it to point to the correct heading.  Its off quite a bit and I cannot adjust as the amount it is off is non-linear.  For example, at 0 degrees it shows 100 degrees.  But at 45 degrees it shows 170 degrees.  Z axis is level and remain constant for the most part.

 


Here is the data I collected, does it makes sense?  I used a compass on my phone and compared to the readings I am getting.

 

 

 

0 degrees North
X 0
Y 155
Z -530

 

Calculated heading: 100

 

 

90 degrees east

 

X -165
Y 100 (shouldn't this read 0 since it is pointing in same direction X was just at?)
Z -530
Calculated Heading: 224

 


180 degress South
X: 0
Y: -290
Z: -540

 

Calculating Heading: 286

 

 

 

270 degrees West

 

X: 250
Y: -100
Z: -550
Calculated Heading: 252

 


One thing I am thinking is odd, if at 0 degrees north X axis reads 0, if I rotate 90 degrees to right, would Y axis now read 0?

 

I am not sure what the axis is measuring, I thought it was force and it I point x axis in one direction, then Y axis in same direction, they would show the same reading...

 

X and Y are 90 degrees in parallel plane.
I ordered another magnometer hoping a different brand will help.  Its still 5883L but different maker of breakout.

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  • 0

    I am tempted to erase my first two replies but I have learned from past experience that even bad advice can sometimes trigger an insight. If I take the dot product of the values of your test I get the following numbers:

    North:   552.20

    East      564.02

    South   612.94

    West    612.37

    If the magnetometer is measuring the strength of the field it is expected that we would have the same number with the dot product of the vectors regardless of the orientation of the magnetometer.  These numbers are close particularly the South and West. I assumed that your angles were precisely 90 degrees as the numbers were crunched using the easy Pythagorean Equation. This would seem to indicate that the magnetometer is working correctly and it is a mathematical translation problem. I am guessing that the N and E were not precisely at right angles and so my calculations would have been off for them.

    Sorry for the inundation of ideas but I use this as a problem solving method.

    John

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  • 0

    I am tempted to erase my first two replies but I have learned from past experience that even bad advice can sometimes trigger an insight. If I take the dot product of the values of your test I get the following numbers:

    North:   552.20

    East      564.02

    South   612.94

    West    612.37

    If the magnetometer is measuring the strength of the field it is expected that we would have the same number with the dot product of the vectors regardless of the orientation of the magnetometer.  These numbers are close particularly the South and West. I assumed that your angles were precisely 90 degrees as the numbers were crunched using the easy Pythagorean Equation. This would seem to indicate that the magnetometer is working correctly and it is a mathematical translation problem. I am guessing that the N and E were not precisely at right angles and so my calculations would have been off for them.

    Sorry for the inundation of ideas but I use this as a problem solving method.

    John

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