Synopsis

void ahrs_update(AHRS_STATE_t *self,
                 float period,
                 float *data);

Description

ahrs_update updates the orientation estimation in the AHRS self. The elapsed time between the previous update and this update is passed as period seconds. The data for this update is passed in data:

• data[0]…data[2] hold the accelerometer X, Y, and Z measurements. Typically these are in g and come direct from a CTL_ACCELEROMETER_t object. However, the units for the accelerometer do not matter as the data are normalized before processing.
• data[3]…data[5] hold the spin rates about the X, Y, and Z axes in radians per second. Typically these come from a CTL_GYROSCOPE_t object, converted from degrees/second to radians/second, and passed into ahrs_update.
• data[6]…data[8] hold the field strength readings for the X, Y, and Z axes. Typically these come from a CTL_MAGNETOMETER_t object.

If the magnetometer measurement is not available and you wish to fuse only accelerometer and gyroscope, you must set the magnetometer values to an IEEE not-a-number (NaN) which is defined as NAN in <math.h. If the accelerometer measurement is invalid (i.e. any axis measurement is NaN or all axis measurements are zero), the AHRS orientation estimation is not updated.

Note

The data held in data is modified during AHRS update.

Thread Safety

ahrs_update is thread safe.