Attitude synchronization of a spacecraft formation without velocity measurement

We consider the quaternion-based attitude synchronization problem of multiple spacecraft without velocity measurements. First, we propose a leader-follower-type control scheme for the attitude synchronization of a spacecraft formation to a desired constant attitude (available only to a single spacecraft called the leader), while maintaining the same attitude during formation maneuvers. Second, we consider the consensus seeking problem, where, no reference attitude is specified, and all spacecraft are required to align their attitudes with the same (possibly time varying) final angular velocity. The communication flow between spacecraft is assumed to be bidirectional. Simulation results of a scenario of four spacecraft are provided to show the effectiveness of the proposed control scheme.