Finite-time attitude set-point tracking for thrust-vectoring spacecraft rendezvous

This paper addresses the optimal orbit rendezvous problem for thrust-vectoring spacecraft. In this scenario, the chaser spacecraft is equipped with only one impulsive thruster fixed in the body frame, while the thrust direction is pointed using attitude control of the spacecraft. An improved particle swarm optimization (PSO) algorithm is employed to generate an optimal multiple-burn rendezvous trajectory in terms of thruster pulse duration and required attitude. A coordinate-free, finite-time, attitude control is developed to ensure that this required thrust vector is met exactly at the prescribed time. The proposed orbit-attitude guidance algorithm is compared with one which utilizes a conventional PSO and is shown to significantly improve performance. In addition, the set-point attitude control is illustrated, in simulation, to deliver the required thrust direction at the prescribed time.