Date of Award

2009

Document Type

Thesis - Open Access

Degree Name

Master of Science in Aerospace Engineering

Department

Aerospace Engineering

Committee Chair

Bogdan Udrea

Committee Member

Hamilton Hagar

Committee Member

Yechiel J. Crispin

Abstract

The purpose of this study is to design and analyze the accuracy of an attitude determination subsystem for a satellite of the CubeSat class by using low cost sensors. CubeSats are nanosatellites that complies a certain amount of layout criterions described by the California Polytechnic State University. A 3-axis attitude determination platform has been designed with emphasis on the use of low cost, off the shelf sensors. This platform features a sun sensor, a magnetometer and an earth sensor. The principles of observation and the description of the acquisition method are explained. The interfacing of the software package and real hardware is emphasized so as to obtain a practical platform for the nano-satellite's Guidance and Control (G&C) tests. Computation of the attitude has been tested using the Three Axis Attitude Determination scheme (TRIAD). A test bench has been designed to be able to perform accurate rotation measurements. Easily feasible test procedures have been used to test the precision of each component of the acquisition and computing scheme. Tests have shown the relevance of the output of each sensing items. Results shown that a lens correction algorithm is needed to have a better accuracy on data computed from the camera used. The current design show that the sun sensor is accurate within 8 degree half cone and the earth sensor is accurate within 1 degree half cone. First attitude determination tests computed with the TRIAD algorithm showed that the overall accuracy of the computation scheme is within 5 degree half cone. This study has been especially focused on providing the general platform for the algorithm. Later studies will be necessary to make the subsystem more robust and accurate enough to be used in a real mission. The different ways to improve the system and its accuracy are discussed both for specific items and the entire sensing module.

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