Finite-time attitude consensus tracking with terminal sliding mode observer

In this paper, a distributed attitude consensus tracking control law is proposed for satellite formation flying by using sliding mode method. First, graph theory and Modified Rodriguez Parameters (MRPs) are introduced to describe the relation and dynamics of the team. Second, distributed terminal sliding mode observers are constructed to estimate the velocity state of rigid bodies in the team. The observer error will converge to zero in finite time. Then, an attitude consensus tracking control law based on sliding mode method is discussed, using the estimated states by the proposed observers. The control law can ensure not only attitude agreement between rigid bodies in the team but also time-varying reference tracking without velocity measurements. Finally, an illustrative example shows that the attitude tracking goal will achieve with the velocity-free consensus control strategy.