Star Sensor Fine Attitude Pointing Model for a Spinning Geosynchronous Satellite

摘要

A fine attitude determination model is developed for a spinning geosynchronous satellite, based upon stellar observations from a V-slit star scanner and ground supplied satellite ephemerides. A true attitude model is determined through numerical integration of Euler's moment equations for a torque-free, rigid, axisymmetric body, and kinematic relations which consist of pitch, roll, yaw, orientation angles. Next, the closed form solutions to the Euler equations are coupled with first-order approximate solutions of the kinematic relations to develop a second order kinematics model. Observation relations, relating stellar slit-plane crossing times, (a priori star identification assumed), to attitude states, are then developed. Finally, a nonlinear least-squares estimation algorithm is used to identify the full satellite attitude state. Simulation is tested for single scan and multiple-scan capability using exact and noise ridden data. Keywords: satellite attitude determination; star sensors; star trackers; autonomous spacecraft navigation. (Theses)