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esa / pykep

PyKEP is a scientific library providing basic tools for research in interplanetary trajectory design.
http://esa.github.io/pykep/
GNU General Public License v3.0
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Problem with Vinf interval values in pl2pl_N_impulses #138

Open cindyangama opened 4 years ago

cindyangama commented 4 years ago

Hello,

I am currently using Pykep's trajopt pl2pl_N_impulses class to design interplanetary trajectories problems.

For one of them I had to specify a very short interval for the Vinf value at launch (less than 100 m/s range) and two DSMs after it before the final impulse to reach the final planet.

The process works well but it seems that the value interval for the initial Vinf is also applied to the N-2 following DSMs as it is shown in the joined results. I would like them to be different since it is restraining the optimization process (and also expect much lower values for spacecraft propulsion).

I did several modifications in a custom copy in order to choose their value intervals independently, which was successful, but I wondered if this behavior was on purpose? Am I using the tool correctly?

Please do not hesitate to ask any additional information if required.

ex1

darioizzo commented 4 years ago

I see a constraint of 3380 m/s int he example you posted, but you mention 100 m/s in the text?

Anyway, yes the constraint on the maximum DV is applied to each DV. Its rather straight forward to change and generalize it, I would welcome a PR on the issue.

cindyangama commented 4 years ago

Thank you for your answer, I was meaning that my Vinf was constrained between 3280 m/s and 3380 m/s (I needed it to be very precise). Ok for the PR, I will post my version.