Re: [Orekit Developers] Kalman Filter

[MAISONOBE Luc <luc.maisonobe@c-s.fr>]

Pau Hebrero Casasayas <Pau.Hebrero-Casasayas@scisys.de> a écrit :

> Hi all,

Hi Pau,

> I have read that there is a Kalman Filter currently under  
> development. We would like to do some real-time orbit determination  
> testing using a Kalman Filter, mainly we are after the noise  
> generated after the OD.
>
> Is there a branch that I can check-out to try it? To which extend is  
> it reliable?

Yes, the branch in the main git repository is called kalman-filter-od.
It can be seen online here :  
<https://www.orekit.org/forge/projects/orekit/repository?utf8=%E2%9C%93&rev=kalman-filter-od>, but simply cheking it out from git is  
simpler.

It is reliable but the API will change very soon. We have started to
refactor the mathematical part so it can be contributed back to
Hipparchus, and Orekit will simply add the space flight dynamics layer
on top of it. You can look at  
<https://github.com/Hipparchus-Math/hipparchus/issues/32>
and at the kalman branch in Hipparchus  
<https://github.com/Hipparchus-Math/hipparchus/tree/kalman>.
I still have to:
  1) add the non-linear (extended) Kalman filter in Hipparchus
  2) split the Orekit implementation so it delegates to Hipparchus

The API changes in Orekit will most certainly be to introduce a
Streams, which are very well suited for real-time long term
runs. Basically, you will have a Stream of measurements as input,
and you will produce a Stream of Stream of Spacecraftstate as
output.

I think the Hipparchus stuff should be ready next week, and the
changes to Orekit will be started after that. We can expect to
have the Orekit kalman-filter-od branch to be merged back to the
development branch in the next few weeks.

best regards,
Luc

> Many thanks in advance,
>
> Pau
>
> ___________________________________________________________
>
> Pau Hebrero Casasayas
> Flight Dynamics Software Engineer
> Space
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