Propagation parameters estimation by Kalman filter

Hi everyone,

I’m using Kalman filter for orbit determination. Several propagator builders were added to the Kalman estimator builder (since I need ISL). I would like to determine some propagation parameters besides the orbital elements. Take drag coefficient as an example. After I set the selected flag of drag coefficient to true, it could process without problems. But I found out that unlike orbital parameters, which could get these parameters for different propagators (marked as a[0], e[0], …, a[1], e[1], …), the propagation parameters are returned with only one set (only one drag coefficient was estimated and returned). What if these satellites have different properties (different drag coefficients), and I would like to estimate the propagation parameters for each propagator? Do you have any idea how could I do that?

I found a piece of codes from KalmanEstimator:

Seems like propagtion parameters with several propagators were not distinguished like orbital parameters. I’m not sure if this is a bug or I didn’t use it correctly. I hope you could help to make it clear. Thank you!

Hi @xche,

Do you have the same name for the differents propagation parameters ? For instance is the name used for the drag coefficient of satellite 1 the same than the one for satellite 2 ? In order to have different parameters estimated the name shall be different.

Kind regard,


Yes, I think by default they have the same name (like orbital parameters), and I didn’t change it.

So in order to estimate them I need to change their names differently? I’ll try it. Thanks for the tips.

Hi xche,

Did you change the names of the propagation parameter drivers that are attached to each satellite ?
If not, the default name is “drag coefficient” and, since the parameter driver logic is to segregate them by name, the Kalman will consider it is the same parameter.
You can try to rename them to “Cd sat 1” and “Cd sat 2” for example and see if this works better with this.

Hi Maxime,

I didn’t change the names. I originally thought it would separate them like orbital parameters, but it seems that it’s not the case. I’ll try to change the names and see. Thank you!