Down velocity in INS/GNSS integration example using synthetic data

[yuzhangjun-gps]

Dear NaveGo-Team, thank you for your work, I do appreciate it.

Performances of the two simulated INS/GNSS systems are compared in the file navego_example_synth.m, but the down velocity seems to be problematic (Down velocity errors of the two simulated INS/GNSS systems are always outside the margin of error).

Down velocity error of IMU2:

[rodralez]

Hi,

First of all, sorry for the super delayed reply.

I cannot see this behavior in the current NaveGo version.

I get this figure for the velocity errors:

Nevertheless, I changed the way of simulating the inertial sensors some months ago and maybe this could cause a problem with the biases estimation.

I will check.

Best wishes.

[yuzhangjun-gps]

Hi,
This is the result of a recent run where the previously mentioned problem seems to have been unresolved. I am looking forward to your early reply.

[rodralez]

Hi,

Thank you for pointing out this problem again.

I re checked my code and found an error in function F_update.m. There was a problem with the sign of matrices DCMbn corresponding to gyros dynamic biases in matrices F and G.

Old matrices were:

F = [F11  F12  F13  DCMbn   Z  ;
    F21  F22  F23   Z       DCMbn  ;
    F31  F32  F33   Z       Z      ;
    Z    Z    Z     Fgg     Z      ;
    Z    Z    Z     Z       Faa    ;
    ];

G = [DCMbn  Z     Z    Z ;
    Z      DCMbn  Z    Z ;
    Z      Z      Z    Z ;
    Z      Z      Fbg    Z ;
    Z      Z      Z    Fba ;
    ];

And new matrices are:

F = [F11  F12  F13  DCMbn   Z  ;
    F21  F22  F23   Z       -DCMbn  ;
    F31  F32  F33   Z       Z      ;
    Z    Z    Z     Fgg     Z      ;
    Z    Z    Z     Z       Faa    ;
    ];

G = [DCMbn  Z     Z    Z ;
    Z      -DCMbn  Z    Z ;
    Z      Z      Z    Z ;
    Z      Z      Fbg    Z ;
    Z      Z      Z    Fba ;
    ];

Moreover, now the default method for simulating the dynamic bias noise in function noise_b_dyn.m is Aggarwal's formulation.

Please, download the last commit and let me know if everything is OK:

Best regards.

[yuzhangjun-gps]

Thanks for your answer @rodralez, the problem mentioned has been solved.