EarthOrbitOpticalNav:

Path: SpacecraftEstimation/Demos/OpticalNavigation

% Demonstrate optical navigation in earth geosynchronous transfer orbit.
 Uses an earth sensor and a star sensor. The earth sensor measures
 the earth chord. The star sensor measures an angle from the nadir 
 vector to the star.

 The gravity model is point mass without any perturbations or
 disturbances such as solar or aerodynamics.

 It is interesting to try the sim without the update step. If you do 
 this you will find that the error gets extremely large after 4 orbits.
 This happens because the covariance grows and eventually at perigee,
 the mean orbit will be hyperbolic. 

 The star sensor assumes that it can see multiple stars. This can
 be accomplished by a wide field of view sensor or by an articulated
 sensor.

 This demo uses the new UKF framework with separate propagate and
 measurement update functions.

 Things to try:

   1. Change the orbit
   2. Change the sensor noise
   3. Change the star vector
   4. Add disturbances.
   5. Use only the earth chord measurement
   6. Turn off the update step
   7. Vary the initial covariances

   Since version 2014.1
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   Copyright (c) 2014 Princeton Satellite Systems, Inc. 
   All rights reserved.
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Children:

Common: Database/Constant
Common: Estimation/KFInitialize
Common: Estimation/UKFPredict
Common: Estimation/UKFUpdate
Common: Graphics/Plot2D
Common: Graphics/TimeLabl
Math: Integration/RK4
Math: Linear/Mag
Math: Linear/Unit
Math: Trigonometry/CosD
Math: Trigonometry/SinD
Orbit: OrbitCoord/RPRA2AE
OrbitMiniToolbox: Support/El2RV
SC: BasicOrbit/Period
SC: BasicOrbit/RHSOrbit
SpacecraftEstimation: SensorMeas/MeasEarthChord
SpacecraftEstimation: SensorMeas/MeasNadirStar

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