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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 -------------------------------------------------------------------------- % -------------------------------------------------------------------------- Copyright (c) 2014 Princeton Satellite Systems, Inc. All rights reserved. --------------------------------------------------------------------------
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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