Dear All,

I am using FXTH8719xxxx Family XZ axis Accelerometer Sensor. I need to find the direction as well how much angle turned by using X-axis ans Z Axis data. If any one can help me the possibility?

Each sensor Z-Axis have the different offset values, help me how to calibrate the Z-axis with the new sensor.

Hi Hulandaivel,

There are several methods to calibrate sensor offsets. The big limitation with an accelerometer is you need to do the calibration phase with quasi-static data. I mean: if you move the FXTH8719xxxx , you will add an acceleration vector on both axis (Z & X) and this will degrade/pervert the calibration... So you have to take care of the sensor rotation by doing very smooth motion (external acceleration should be very small compared to the 1g-force).

About calibration algorithms:

1. You can collect data/measurements around the circle in a buffer. When the full revolution is done, you compute the Z offset with an optimization method to minimize the standard deviation of the 1g vector on all measurements.

2. You can calculate the circle center with 3 points only. (Basic equations & resolution)

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The final angle can be calulated with the following equation:

-Z0 the Z bias

- Z current / X current are the actual measurements.

Note that these equations are only valid in a static model and are using the 1g gravitational force as reference.

I hope it helps.

Thanks,

Anthony