无速度反馈的航天器姿轨耦合跟踪控制

提出了一种无速度反馈的航天器姿轨耦合跟踪控制算法。首先建立起基于对偶四元数的带扰动和参数不确定性的航天器姿轨耦合动力学模型。然后基于浸入与不变流形理论设计了速度观测器，通过增益注入对非线性项抑制，从而同时估计角速度和线速度。利用李雅普诺夫函数分析了观测器状态量的收敛性以及注入增益的有界性，证明了该观测器的指数稳定性。最后设计了一个比例-微分（PD）位置与姿态跟踪控制器，该控制器可以实现航天器的任意姿态与位置跟踪，分析了这种观测-控制结构的闭环系统渐近稳定性。仿真验证了该速度观测器和控制器的有效性以及对于参数不确定性和测量噪声具有较好的鲁棒性。

Attitude and position tracking control for spacecraft without velocity measurement

An attitude and position coupled tracking control algorithm for spacecraft without velocity feedback is proposed in this paper. A coupling dynamics model for the spacecraft with perturbations and parameter uncertainties based on dual quaternions is established firstly. Then, based on the theory of immersion and invariance, a velocity observer is designed. The observer estimates the angular velocity and the linear velocity together, and suppresses the nonlinear terms by dynamic scaling injection. The convergence of the observer states and the boundedness of injection gain are analyzed theoretically by Lyapunov function, and the exponential stability of the observer is proved. The rate of convergence of the observer states can be changed by adjusting the gains. Finally, a PD position and attitude tracking controller is designed. The controller can realize tracking of any attitude and position of the spacecraft. The asymptotic stability of the closed-loop system of this observer-controller cascade structure is analyzed. Simulation verifies the effectiveness of the observer-controller system and its robustness to uncertain parameters and measurement noises.