Magnetic attitude control of LAICE satellite with aerodynamic stabilization

Abstract

The Lower Atmosphere Ionosphere Coupling Experiment (LAICE) is a NanoSatellite which will be performing in-situ measurements of neutral and ion densities in the mesosphere, lower thermosphere, and ionosphere and correlating them to measurements of gravity waves in the lower atmosphere. The satellite is based on a new 6U CubeSat form factor based on the IlliniSat 2 bus developed at the University of Illinois at Urbana-Champaign. The satellite’s payloads need to be oriented such that three instruments are oriented along the velocity direction of the satellite, while a fourth instrument is pointed towards nadir. The attitude determination and control system must achieve the attitude pointing requirements (5° from nominal attitude) with minimum of cost and low power. The satellite will therefore make use of magnetic torque coils augmented with aerodynamic stabilization to accomplish the mission attitude control requirements. The proposed control method relies on passive aerodynamic stabilization of the spacecraft to maintain pointing in the satellite normal frame. The aerodynamic stabilization reduces the dimensionality of the magnetic attitude control to a one-dimensional problem. The major contributions of this work include the development of an object-oriented attitude control library with which to program flight code as well as simulate satellite dynamics to validate the flight code; the development and tuning of an Extended Kalman Filter for attitude determination using low-cost magnetometers and MEMS gyros; the development and tuning of a hybrid attitude control algorithm for magnetic torque coils which can reliably detumble and reorient the satellite; the development of an efficient graphical drag model for computing aerodynamic torques; and the novel use of a tri-axial Helmholtz cage for performing a Hardware-in-Loop optimization of the coupled attitude determination and control system.