Advanced Attitude Control of Pico Sized Satellites

Paper number

IAC-05-C1.3.06

Author

Mr. Jesper Abilgaard Larsen, Aalborg University, Denmark

Coauthor

Mr. Rouzbeh Amini, Delft University of Technology, The Netherlands

Coauthor

Dr. Roozbeh Izadi-Zamanabadi, Aalborg University, Denmark

Year

2005

Abstract

In the summer of 2003 the first student satellite, AAU-cubesat, developed at Aalborg University, was launched. Although the satellite failed in achieving all mission requirements, the primary goals were fulfilled. The success of this first satellite has initiated the development of its successor, the AAUSAT-II, which is to be launched in the autumn of 2005.  This satellite's primary scientific missions are to measure gamma bursts from supernovas and x-ray emission from the sun. In order to be able to point at the sun with sufficient accuracy the satellite will use a combination of conventional magnetorquers along with miniature momentum wheels.  Since the AAUSAT-II will be the first pico size satellite ever to utilize momentum wheels this has lead to a secondary mission objective, which is to make a pointing accuracy study.

Since the AAUSAT-II is going to be launched into a low earth orbit the overall control philosophy for the attitude control system (ACS) is to use magnetorquers for detumbling, coarse pointing and momentum off-loading while using momentum wheels for fine pointing and disturbance suppression. Using the ACS, it is vital that faults occurring in the system can be diagnosed. Thus, fault detection and isolation (FDI) has been built into the system. The actuation redundancy given by the combined magnetorquer/momentum wheel system makes it possible on the basis of the FDI to make fault tolerant control.

This paper deals with the analysis and design of the ACS for the AAUSAT-II. The overall control strategies along with the supervisory controller is designed and analyzed.

For the nominal system and some of the more likely fault modes, power optimal controllers are developed.  The entire system is implemented and simulated using MatLab Simulink and the AAUSAT-toolbox, and it has been found that the ACS is able to perform satisfactorily and within the specified margins. It is also found that the ACS is able to continue operation within the specifications with the loss one actuator.

Abstract document

IAC-05-C1.3.06.pdf

Manuscript document

IAC-05-C1.3.06.pdf (🔒 authorized access only).

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