[Paparazzi-devel] I donot understand the ahrs_mlkf_update_accel(struct FloatVect3 *accel)

[sulijune]

Hi,
In the 
sw/airborne/subsystems/ahrs/ahrs_float_mlkf.c
file:
128 void ahrs_mlkf_update_accel(struct FloatVect3 *accel)
129 {
130   struct FloatVect3 imu_g = *accel;
131   const float alpha = 0.92;
132   ahrs_mlkf.lp_accel = alpha * ahrs_mlkf.lp_accel +
133                        (1. - alpha) * (float_vect3_norm(&imu_g) - 9.81);
134   const struct FloatVect3 earth_g = {0.,  0., -9.81 };
135   const float dn = 250 * fabs(ahrs_mlkf.lp_accel);
136   struct FloatVect3 g_noise = {1. + dn, 1. + dn, 1. + dn};
137   update_state(&earth_g, &imu_g, &g_noise);
138   reset_state();
139 }
I can't understand the 135 and 136.
Why the accel multiply the '250' ?
Why the 'dn' + 1?
Who can explain for me？
Thanks!






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