vrays2012
(vrays2012)
August 4, 2015, 7:07am
1
I am learning the EKF algorithm.
I have seen the https://github.com/priseborough/InertialNav/blob/master/derivations/SymbolicOutput24.txt

as this article said, the predict state is X(k+1|k)= F* X(k|k),
so q0 = q0 - 0.5 * (dax * q1 + day * q2 + daz * q3) + q1 * dax_b + q2 * day_b+ q3 * daz_b;

but we all know q0 = q0 - 0.5 * (dax * q1 + day * q2 + daz * q3).

Does anyone know what is wrong about my understanding?
Ths

vrays2012
(vrays2012)
August 5, 2015, 12:46am
2
as the article said,
X(k+1|k)= F* X(k|k)

q0= q0+ SF(10)q1+ SF(12)q2+ SF(11)q3+ SF(15)dax_b+ SF(16)day_b+ SF(17)daz_b
= q0- 0.5 (dax q1+ day q2+ daz q3)+ q1 dax_b+ q2 day_b+ q3*daz_b

vrays2012
(vrays2012)
August 5, 2015, 9:26am
3
I think I have get the reason.

‘F’ is used to calcaulte the covariance, and can not used to calcalute the predict state.
‘f’ is used to calculate predict state, and ‘F’ is getted from 'f’s jacobian.