(Georgia Institute of Technology, 2014-08)
Filipe, Nuno; Holzinger, Marcus J.; Tsiotras, Panagiotis
Satellite proximity operations have been identified by NASA and the USAF as a crucial
technology that could enable a series of new missions in space. Such missions would require
a satellite to simultaneously and accurately track time-varying relative position and attitude
profiles. Moreover, the mass and moment of inertia of a satellite are also typically time-
varying, which makes this problem even more challenging. Based on recent results in dual
quaternions, a nonlinear adaptive position and attitude tracking controller for satellites
with unknown and time-varying mass and inertia matrix is proposed. Dual quaternions are
used to represent jointly the position and attitude of the satellite. The controller is shown
to ensure almost global asymptotic stability of the combined translational and rotational
position and velocity tracking errors. Moreover, sufficient conditions on the reference
motion are provided that guarantee mass and inertia matrix identification. The controller
compensates for the gravity force, the gravity-gradient torque, Earth's oblateness, and
unknown constant disturbance forces and torques. The proposed controller is especially
suited for satellites with relatively high and quick variations of mass and moment of inertia,
such as highly maneuverable small satellites equipped with relatively powerful thrusters
and control moment gyros.