the Kalman implementation questions

[yywe]

according to my understanding, not quite understand the implementation of the Kalman:
(1)
...
z_k_pre = z_k.copy()
...
//# Update state vector x_k
x_k += np.array( K_k.dot(z_k-z_k_pre) ).ravel()
here z_k - z_k_pre means the current observation subtract the previous observation. according to standard Kalman text book, shouldn't here be observation subtract prediction ? and why the prediction part is just simply set to the previous observation (z_k_pre = z_k.copy())
(2)
....
x_k[:3] = np.zeros(3)
x_k[:3] += tstep * (-x_k[:3]+z_k[:3])
....
here the first 3 elements is forced to 0. so actually it is
x_k[:3] += tstep * (z_k[:3]),
since z_k[:3] is the angular velocity, the result is the amount of changed angles.

any help?

[thomas-haslwanter]

I am just looking into that again, and I am seriously wondering if my implementation was correct. Currently, I cannot even find the definition of the QUEST that I used at the time :(
Sorry - Will keep you updated.

[gcosne]

Hi @thomas-haslwanter,

I can see that the Kalman code have been changed since @stweiyy comment. Do you have any update on the definition of QUEST you used ?
How confident are you in the Kalman implementation?

thank you for your help