Relative attitude control of two spacecraft on SO(3) using line-of-sight observations

This paper studies relative attitude control of two spacecraft, considered as rigid bodies. A relative attitude determination scheme and a relative attitude control system are developed based on the line-of-sight (LOS) observations between two spacecraft, and another set of LOS observations to a common object from two spacecraft. The proposed control system is distinct from other attitude formation control systems that require the full absolute attitude of spacecraft and the full relative attitude between them. Assuming that the relative positions of two spacecraft and the common object are fixed, it is shown that the desired relative attitude between two spacecraft is almost globally asymptotically stable. A numerical example is presented to illustrate the desirable properties of the proposed relative attitude control system.