Robust and Adaptive Attitude Control Of Spacecraft Using Solar Radiation Pressure

Satellites in orbit are expected to maintain a preset attitude either pointing towards Earth (in case of satellites for weather) or pointing towards space for the purpose of research and exploration. The satellite as a system though is extremely nonlinear and the system parameters are not easily available. The goal of this thesis is to develop robust and adaptive control laws that can be used to control the attitude of satellites in elliptic orbits. The attitude of the satellite is controlled by the use of Solar Radiation Pressure (SRP) on the solar panels of the satellite. The SRP is basically a mechanical pressure caused by the photons impinging on the solar panels. By deflecting the solar panels the area that is impinged by photons is varied and therefore the torque on the satellite is also varied. This torque is used to control the attitude of the satellite which is expected to be maintained at a preset orientation. In this work, different methods will be used to control the satellite under different conditions involving state and output feedback. For state feedback all the states of the system are assumed to be available. In this case the states would involve the pitch angle, angular velocity and acceleration of the satellite. However the information on these states may not be easily available. Output feedback is when the output alone of the system is used and only an estimation of other states is used. Simulation is used to project the results of the different types of controllers