Attitude control of the ESEO satellite
- Paper number
IAC-05-C1.P.06
- Author
Mr. Jøran Antonsen, NAROM - Norwegian Centre for Space-Related Education, Norway
- Coauthor
Raymond Kristiansen, Narvik University College, Norway
- Coauthor
Dr. Per Johan Nicklasson, Narvik University College, Norway
- Year
2005
- Abstract
The Student Space Exploration and Technology Initiative project (SSETI) was founded by the support of the European Space Agency (ESA) in the year 2000. Today SSETI is formed as an association with ESA as an honorary member. The main objective of the SSETI project is to create a network of students, educational institutions and organizations to perform the distributed design, construction and launch of spacecraft. The European Student Earth Orbiter (ESEO) is the first micro satellite in the SSETI project. The work on the ESEO started in October 2000 and the satellite is planned for launch in 2006. Today there are students from more than twelve European countries collaborating in building the ESEO. In addition, other SSETI missions have been started the last years such as the SSETI Express and the European Student Moon Orbiter (ESMO). The former is planned to be launched in May or June 2005 from Kazakhstan and the design of the latter started with a feasibility study in August 2004. The contribution of this paper is a case study of the attitude control system of the ESEO satellite. The satellite is equipped with four attitude control thrusters (ACS thrusters), one reaction wheel mounted on the pitch axis, one main orbit control thruster (OCS thrusters) for orbital manoeuvres, and additional four reaction control thrusters (RCS thrusters) used to correct orbital manoeuvres since the OCS thrust vector might not go through the centre of mass. The RCS thrusters are also used as a redundancy for the ACS thrusters. Mathematical models of the satellite dynamics and kinematics are presented by the use of Euler parameter representation. A definition of the reference frames used throughout the paper is given. Disturbance torques and actuator dynamics of the satellites ACS thrusters and reaction wheel are derived, and the Moore-Penrose pseudo inverse is used to compute the actuator vector in terms of the four ACS thrusters and the reaction wheel. Different methods for thruster implementation are discussed, such as pulse width modulation, pulse width pulse frequency modulation. A Bang Bang controller with deadzone is used to easily control the thrusters. Four attitude controllers are derived using linear and nonlinear control theory with the ACS thrusters and the reaction wheel as actuators. A linear PD controller with wheel disturbance compensation and a linear quadratic (LQ) optimal controller are derived, both based on a linearized model of the satellite. The advantage of using nonlinear controllers is mentioned and nonlinear controllers based on Lyapunov theory and feedback linearization are derived. The response of the four controllers are compared based on simulation results in Matlab and a suggestion for suitable controllers is given with respect to step response, power consumption and robustness towards external disturbances.
- Abstract document
- Manuscript document
IAC-05-C1.P.06.pdf (🔒 authorized access only).
To get the manuscript, please contact IAF Secretariat.