Publication: Satellite attitude determination by using gps
Date
2008-04-01
Authors
Wahidon, Noor Rasyidah
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Abstract
Global Positioning System (GPS) has been used successfully to determine position and attitude of a spacecraft. A direct calculation method of position and attitude determination for a satellite is described. The satellite position and attitude is calculated and presented via the Graphical User Interface (GUI) by using the MATLAB 7.0. In general, this GUI will show the satellite position in ECEF XYZ coordinates and geodetic coordinates (latitude, longitude and altitude), satellite attitude (yaw angle, pitch angle and roll angle) and basic theory of GPS.
The satellite position is determined by knowing the GPS satellite coordinates in ECEF XYZ, GPS satellite pseudoranges in meters and receiver position estimate in ECEF XYZ. In this thesis, the GPS receiver will detect four GPS satellites visible on the orbit in order to determine satellite position. A direct calculation method using the WGS 84 transformations is described.
Satellite attitude is determined by using three antenna systems which are master antenna and two slave antennas. According to the relations between the local coordinates and the body frame coordinates, the formulas for computing yaw, pitch and roll can be derived directly. A direct calculation method to determine the satellite attitude by knowing the two local coordinates of the slave antennas are described.