Spacecraft Relative Attitude Formation Tracking on SO(3) Based on Line-of-Sight Measurements Open Access
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This thesis investigates the use of line-of-sight (LOS) measurements for the control of relative attitude formation among multiple spacecraft. It is based on the fact that two pointing directions, referring to LOS measurements, from the spacecraft to distinct objects can determine the absolute attitude of spacecraft. With the same approach, LOS measurements from cost-effective vision-based sensors can be applied to obtain the relative attitude among spacecraft. In the proposed approach, high accuracy of attitude control and simpler control scheme can be constructed by designing the control law in terms of LOS measurements. In addition, the relative attitude controller provides almost global exponential stability on the nonlinear configuration manifold of relative attitude. The described properties are illustrated by numerical examples.In conventional approaches, the absolute attitude is measured locally by using an inertial measurement unit, and they are compared to determine relative attitude, thereby causing the accumulation of measurement errors and complex controller structures.