Attitude Dynamics Model Of A Cubesat With Reaction Wheels For An Extended Kalman Filter

—This paper presents a derivation of the attitude dynamics equations of motion of a CubeSat with reaction wheels. The rigid-body equations of motion can be extended to any number of arbitrarily-oriented and arbitrarily-located reaction wheels. The equations of motion are implemented and validated using numerical simulations. It is then shown how the resulting equations of motion can be propagated within a quaternion-based extended Kalman filter. This filter combines attitude quaternion and angular velocity measurements with the derived attitude dynamics model. For the simulation conditions used in this research, the filter provides an improved estimate of the CubeSat’s attitude quaternion and angular rates.