AGI.com Blogs

You Won’t Believe this One Easy Trick Orbit Designers Don’t Want You to Know

By: Jens Ramrath

It actually worked, you clicked on it - sucker. I guess now I’ll have to come up with something interesting for you. Hey, how about me telling you about auto-sequences and why they are awesome. Here we go:

Did you ever want to repeat a specific set of segments but didn’t know exactly when to start or how many times you needed to repeat them? Station keeping of your satellite is a good example for this. You may just want to propagate it until just before you violate whatever constraint you have on your orbit, then trigger a target sequence that gets you back to where you need to be. You want this to happen whenever necessary for some duration. You could create the target sequence and copy it multiple times to cover your required duration.

Or you could use auto-sequences. Auto-sequences are basically like subroutines to the regular MCS. They contain the segments you want to run when certain conditions are met. So if you are hitting your station-keeping constraint, go into an auto-sequence to perform a maneuver. Then come back to the regular propagate segment and continue until the constraint is violated again.

Here is how you set this up. Create a new auto-sequence using the Automatic Sequence Browser and give it a meaningful name.

When you go back to Edit, you can see that the auto sequence is just like the regular MCS. Add your orbit maintenance logic in here

Now we need to call this maneuver sequence whenever we violate (or are about to violate) our orbit constraints. Go back to your main MCS and add an additional stopping condition. Under Sequence, specify that instead of stopping, you want to go into the orbit maintenance auto-sequence.

That should be it. Astrogator will now propagate until the orbit constraints are violated and jump into the maintenance sequence. Once it is done with that it’ll go back into the main sequence. This will repeated until the duration stopping condition stops the entire process.

Posted: 8/21/2017 11:39:43 AM


Tags