Orbit and control design for forming and keeping fly-around

This paper presents the orbit and controller design for spacecraft to approach and fly around a target in the circular orbit. Discussed in the Local-Vertical-Local-Horizontal (LVLH) frame, the process of forming and keeping relative fly-around motion is divided into three phases: the parking phase, the homing phase and the fly-around phase. In the parking phase, the main tasks include seeking the target, the transition from ground navigation to self-navigation and the amendment of transition orbit. In the homing phase, the chaser is guided to the target's orbit as a co-orbital satellite. In the fly-around phase, the chaser is guided and to fly around the target in a required orbit satisfying certain task demands. Once the task is completed, the chaser stays in the target's orbit as a co-orbital satellite and turns into dormancy state. The LQR controllers are designed based on the classical Clohessy-Wiltshire equations. Besides, control trigger and shutter are designed. In the end, design example and simulation are given. Analysis of the result indicates that the orbit and control design are practical and valid.