Lever arm for velocities

Question

Lever arm for velocities

brumann opened this issue 6 years ago · comments

I am not sure to understand how you are using the lever arm for the computation of the position.
In fact, I have the impression that you use it for the position but not for the velocity

" zp = Tpr * ([lat_e(i); lon_e(i); h_e(i);] - [gps.lat(j); gps.lon(j); gps.h(j);]) ...
+ (DCMbn * gps.larm);

zv = (vel_e(i,:) - gps.vel(j,:))';    "  (from ins_gps.m)

Am I right or did I misunderstand the script ?

Thank you in advance for your answer !
And thank you for your code.

Rodrigo Gonzalez · Answer 1 · Tue Sep 11 2018 04:41:37 GMT+0800 (China Standard Time)

El lun., 3 sept. 2018 a las 8:10, brumann (<notifications@github.com>) wrote:

I am not sure to understand how you are using the lever arm for the computation of the position. In fact, I have the impression that you use it for the position but not for the velocity " zp = Tpr * ([lat_e(i); lon_e(i); h_e(i);] - [gps.lat(j); gps.lon(j); gps.h(j);]) ... + (DCMbn * gps.larm); zv = (vel_e(i,:) - gps.vel(j,:))'; " (from ins_gps.m) Am I wright or did I misunderstand the script ?

Hi brumann, You are correct. NaveGo does not correct lever arm for velocity, mostly because I didn't see any impact when using noisy MEMS inertial sensors. Maybe it could be a good idea to implement lever-arm velocity correction for higher grade sensors. Regards. -- Rodrigo Gonzalez

brumann · Answer 2 · Tue Sep 11 2018 14:26:58 GMT+0800 (China Standard Time)

Hi Rodrigo,

Thank you very much for the answer, since we are using a high grade IMU it improved a bit the accuracy.
We changed " zv = (vel_e(i,:) - gps.vel(j,:))'; " to
"zv = (vel_e(i,:) - (gps_.vel(j,:) + (gps_.larm'.([ roll_e(i) - roll_e(i-1) , pitch_e(i) - pitch_e(i-1) , yaw_e(i) - yaw_e(i-1) ])).(1/(ti(2) - ti(1)))))'; "

Regards