Constrained SPS Design Tool

[darianvp]

Issue referring to constrained SPS design tool which searches for highest performing SPS designs inside a orbital parametric scan generated in STK within a constrained feasible design region.

[darianvp]

The current version of the SPS constrained design tool is used to find the highest performing SPS design within a constrained orbital design space. The performance parameters of the best design are outputs of the function, as are some system parameters such as transmitter/generator mass, steady-state temperature, and approximate battery size necessary to eliminate an average blackout event. The calculation of the battery size needs to be improved by looking specifically at events when the SPS is in range of the target but eclipsed, instead of just blackout events (when the SPS may or may not be in range).

I have also incorporated an optimizer into the constrained design tool so that the selected solution inside the feasible design space has the maximum possible link efficiency.

Constraints reducing the design space are:

1. Total SPS active time
2. Maximum target blackout duration
3. Mean power delivered to target
4. Pointing accuracy of transmitter

The free design variable is:

1. Transmitter aperture size

The only factor which is ignored in this version of the problem is the aspect of orbital stability which was incorporated in the weighted objective function approach. Will look into applying constraint on the maximum slew rate of argument of perigee.

[darianvp]

Calculation of slew rate in argument of perigee matches somewhat, but not closely, with results as seen in STK. The SPS constrained design model considers perturbations to the orbit from Earth's gravity, and form the oblateness of the moon, whereas (it seems that) STK only considers the lunar oblateness.

However when removing the effect of the Earths gravity to compare the perigee slew rates, the equations used in the SPS design tool expect a rate of -35 deg per year for an orbit with 10 km perigee and 4000 km apogee. This is slightly larger than what is observed in STK, where the rate is approximately -25 to -30 deg per year. However the change in argument of perigee in STK is estimated visually, not from measurement/calculation.

[darianvp]

Text files containing durations for events where the SPS would require stored power (ie. SPS in range of target, both SPS and target are eclipsed):

MeanStoredPowerEvent_Inertial_Extended_SouthPole_IncrementedRes_Inertial.txt TotalStoredPowerEvent_Inertial_Extended_SouthPole_IncrementedRes_Inertial.txt MaxStoredPowerEvent_Inertial_Extended_SouthPole_IncrementedRes_Inertial.txt

Most scenarios which I have tested so far show that the addition of a battery would lead to a < 10 hour reduction in total blackout duration at the target. In the case of a large transmitter (100 kW), this battery may weigh more than 200 kg in order to suppress the maximum "SPS stored power" event.

[darianvp]

Closing this issue to open a new one for referencing the updates to the scripts in order to accomodate an equatorial orbit data set.