Attitude Estimation for a Deorbiter CubeSat

This paper investigates the attitude estimation ca pabilities of a debris-removing nanosatellite called deorbite CubeSat. The spacecraft is designed based on the utilizatioi of commercially-available components with long space heritage which are embedded in an eight-unit form factor. The attitud. estimation machinery employed in this work is a discrete time, quaternion-based, extended Kalman filter, which utilize measurements provided by a three-axis rate sensor, five su sensors, and a three-axis magnetometer. To obtain a linear state space model, gravity gradient and magnetic disturbance torque are included in the plant model, and the model is linearizec with respect to the process noise and the states, namely the inertial angular velocities and the quaternions. measurement noises are modelled based on zero-mean Gaussian distributions and are quantified based on the performance of the state-of-the art, commercial-of-the-shelf devices. A Monte Carlo simulatioi is created to analyze the performance of the estimator agains various initial angular velocities and quaternions, both in the sunlit and in the eclipsed portions of the orbit. In light o the results, the accuracy of the deorbiter CubeSat's attitud knowledge is discussed.