Abstract: In short range guidance stage, eccentric low-level continuous vector thruster and transformed torque equipment were used to maintain the close approaching and circling of specific object, and complete simultaneously orbit control and light of sight(LOS) stabilization. Relative coupling attitude and orbit dynamic model was established based on T-H equation and error quaternion. Expected relative position gaits were designed respectively for close approaching phase and circling phase. Expected attitude was computed based on LOS angles. Traditional θ-D method can only linearize dynamic equation at start point which hold limited neighbor stable area that can not cover large alteration of relative states during the process. Piecewise linearized θ-D suboptimal controller was proposed based on iterative optimal theory and utilized in relative attitude and orbit control, in which vector part of error quaternion was directly used for state feedback. Decent dimension alternation was made for coupling attitude and position state equation. Simulation results demonstrate that this method are effective.

Key words: Cooperative translation and attitude control, Iterative optimization, Light of sight stabilization, Error quaternion, Spacecraft