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Path: SpacecraftEstimation/Demos/AttitudeEstimation
% Simulate attitude determination for a momentum bias spacecraft. At this point we do not include any real actuators or sensors. The orbit is modeled and the spacecraft controls errors with respect to the LVLH frame. ------------------------------------------------------------------------- Specification ------------------------------------------------------------------------- Ours is a Gravity gradient stabilization satellite with two analog medium sun sensors and one magnetometer for attitude knowledge. We are using Magnetorquer rods as our controller which is basically a PD controller and also a small momentum wheel with angular momentum of 1 Nms and with constant speed on the pitch axis to counter the external disturbance. The nadir pointing accuracy required is < 5 degrees and the attitude errors in all the three axes should be less than 3 degrees. The inertia in the three directions are Ix=120, Iy=120 and Iz=1.3. The orbit radius is 6718+352 Kms (low earth orbit satellite). The inclination is 28.45 deg. The damping ratios and natural frequencies are: Tach loop: zeta = 0.7621 wN= 0.5 Pitch and Roll loop: zeta = 0.7621 wN = 0.009 Yaw loop: zeta = 1.0 wN = 0.15 ------------------------------------------------------------------------- See also IC623X3, PDDesign, PIDesign, QForm, QLVLH, QMult, QPose, Constant, NPlot, Plot2D, TimeGUI, RK4, JD2000, SunMagAttDet, TOrbit, RVFromKepler, MagField, SunV1, FPSensors ------------------------------------------------------------------------- % -------------------------------------------------------------------------- Copyright 1999, 2016 Princeton Satellite Systems, Inc. All rights reserved. -------------------------------------------------------------------------- Since version 5.5 (2003) 2016.1 Switch to newer IGRF11 model (from 1995 data) for the Earth --------------------------------------------------------------------------
AeroUtils: Coord/QLVLH Common: Control/PDDesign Common: Control/PIDesign Common: Database/Constant Common: Graphics/Plot2D Common: Graphics/TimeGUI Common: MassProperties/IC623X3 Common: Quaternion/QForm Common: Quaternion/QMult Common: Quaternion/QPose Common: Time/JD2000 Math: Integration/RK4 SC: BasicOrbit/RVFromKepler SC: Environs/MagField SC: Ephem/SunV1 SC: Sensor/FPSensors SpacecraftEstimation: AttitudeEstimation/SunMagAttDet
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