接近和跟踪非合作机动目标的非线性最优控制

航天器在实施对空间非合作目标的近程操作任务中，需要接近目标并保持在目标附近的特定方位，对目标指定部位随动跟踪和观测。针对非合作机动目标的接近和视线跟踪的六自由度控制问题，根据视线坐标系下的相对轨道方程和体坐标系下的相对误差四元数姿态方程，建立了航天器间近距离相对运动的轨道和姿态联合控制模型。考虑模型的非线性、时变性和计算的快速性，采用θ-D控制方法进行接近和视线跟踪的轨道和姿态联合控制。为了减小跟踪同时存在轨道和姿态机动的非合作目标的控制误差，应用Lyapunov最小-最大定理设计了θ-D修正控制器，改善非合作目标同时进行姿态和轨道机动时的控制性能。仿真验证了模型的正确性和控制器良好的跟踪性能。

Nonlinear Optimal Control of Spacecraft Approaching and Tracking a Non Cooperative Maneuvering Object

In the space operation tasks of a non cooperative target, it is crucial for the chaser to approach to the target and observe it in a specified close position. In this paper, for the six degrees of freedom control of approaching and tracking the non cooperative target, the model of attitude and orbit coupled dynamics is set up based on the orbit dynamics described in the line of sight coordinate frame and the attitude dynamics described in the relative error of quaternion in the body coordinate frame. IN view of nonlinearity, time variability and computational speed, the θ-D control method is employed to control the attitude and orbit coupled dynamics for approaching and tracking. In order to reduce the control error of the target with orbit and attitude maneuver, Lyapunov min max approach is used to design the θ-D controller so that when the non cooperative target is maneuvering and tumbling, the control accuracy can be improved. The simulation results confirm the validity of this model and the good tracking performance of the proposed controller.