空间绳系组合体的继电型控制离轨策略

为了使空间绳系组合体更好地完成空间碎片清理任务，提出一种更接近工程实际应用的继电型推力（Bang-Bang）离轨控制策略。利用带有差动间隙的Bang-Bang控制策略，实现绳系组合体切向的继电式推力加速；设计了一种全新的被动式卷扬机构，以避免在使用继电式推力离轨的过程中多次开关发动机对绳系组合体带来的负面影响；针对径向推力设计了输入受限的滑模控制器，且最终控制指令同样以继电式推力形式实现，抑制了离轨过程中绳系组合体的面内摆动。数值仿真结果显示，继电型推力能够实现与连续推力近似的效果，能够将绳系组合体的摆动角度抑制在一个较小的范围内；整个离轨控制策略能够使得空间绳系组合体在保持姿态稳定的前提下将空间碎片拖曳到坟墓轨道。

De-orbit strategy using Bang-Bang control for space tethered-combination

To enable better task accomplishment of space tethered-combination in space debris removal, we propose a de-orbit strategy using Bang-Bang thrust, which is closer to the engineering application. Firstly, a Bang-Bang controller with differential clearance is used to realize the Bang-Bang thrust acceleration of space tethered-combination. In the process of de-orbit using Bang-Bang thrust, the engine needs to be switched on and off repeatedly. Therefore, a new passive winch mechanism is designed to avoid the negative effects of engine switching. A sliding mode controller with input constraints is designed for radial thrust to suppress the in-plane swing of the tether-combination in the process of de-orbit, and the control is also realized by Bang-Bang thrust. The simulation results show that Bang-Bang thrust can achieve similar results with continuous thrust that suppress the in-plane swing angle in a narrow range. The de-orbit strategy can make space tethered-combination complete the mission that drag space debris to graveyard orbit on the basis of ensuring the attitude stabilization control.