航天器逼近自由翻滚目标的自适应相对运动控制

ADAPTIVE RELATIVE MOTION CONTROL OF SPACECRAFT APPROACHING A TUMBLING TARGET

研究含有模型不确定性且受未知外干扰的追踪航天器自主逼近空间中一自由翻滚目标的6自由度(6DOF)相对运动控制问题.首先在追踪器本体系中建立了非线性耦合的6DOF相对运动模型,并将其化为关于追踪器和目标器未知惯性参数和追踪器未知推力偏心距的参数化形式.再基于该参数化模型设计了一种自适应非线性控制器,其中利用基于投影的自适应算法保证了在线估计参数的有界性.所设计的自适应控制器不仅显著减少了系统在线估计的参数数量,且能保证6DOF闭环系统的位置和姿态误差收敛到原点的小邻域内.仿真算例验证了所提出控制器的有效性.

Six degrees-of-freedom （6DOF） relative motion control is investigated for a chaser spacecraft with modeling uncertainties and unknown external disturbances to approach a tumbling space target. First, a nonlinear and coupled 6DOF relative motion model is expressed in the chaser body-fixed frame and formulated as a parameterized form about unknown inertia parameters of the two spacecrafts and unknown thrust misalignment of the chaser. Then, based on the parameterized model, an adaptive nonlinear controller is designed, where the unknown parameters are estimated online with a projection-based adaptive algorithm such that its boundedness can be guaranteed. By the use of the proposed adaptive controller, the amount of estimated parameters is reduced significantly, and position and attitude errors of the 6DOF closed-loop system converge to a small neighborhood of the origin. Simulation example shows the effectiveness of the proposed controller.