• Rasmus Holst
4. semester, Regulering og Automation, Kandidat (Kandidatuddannelse)
This thesis describes the design and anal- ysis of a nonlinear attitude control system for a CubeSat sized satellite based on the structure of the AAUSAT satellites.
An analysis of the main disturbances is made with the conclusion that only the magnetic dipole moment needs to be taken into account when performing at- titude control, as this disturbance is 10 times larger than the rest combined.
An estimation of the satellite dipole mo- ment is made as a bias estimation by an Extended Kalman Filter. The resulting estimate is correct within 8 % of the true dipole moment when estimating on data basen on a slowly tumbling satellite with state noise.
A sliding mode controller is used as the nonlinear controller and uses the mag- netic dipole estimate from the Extended Kalman Filter to counteract this distur- bance. The result is a controller capa- ble of following a Nadir reference within an axis-wise error of 10 degrees. The downside to the controller is the constant power consumption needed, in order to counteract the magnetic dipole moment of the satellite.
Udgivelsesdato15 aug. 2014
Antal sider87
ID: 202321140