带微分观测器的双环姿态跟踪控制

针对捕获非合作目标航天器的姿态跟踪控制问题，给出了一种双环姿态跟踪控制器。通过引入虚拟角速度将二阶姿态运动方程分解为内外环独立的子系统。外环预设有界虚拟角速度使航天器姿态渐近收敛于期望姿态；内环采用二阶微分观测器精确估计由转动惯量摄动、外部干扰和饱和超幅部分组成的不确定项，基于观测值的鲁棒姿态控制器使内环角速度指数收敛于外环虚拟角速度。双环姿态跟踪控制能够满足控制饱和及角速度有界约束下的跟踪精度和闭环系统的全局渐近稳定性。数值仿真验证了该控制器的鲁棒性和有效性。 

Dual-Loop Attitude Tracking Control with Differential Observer

A dual-loop attitude tracking robust controller was presented for rigid spacecraft to deal with the attitude tracking control problem. Attitude dynamic equation was decomposed to two independent subsystems by presetting a bounded virtual angular velocity. The preset virtual angular velocity in outside loop was used to ensure the attitude asymptotical converge to desired attitude,and was taken as a virtual input of inner loop subsystem. The uncertainty composed of rotational inertia perturbation, external disturbance and exceed saturated amplitude could be estimated by second-order differential observer accurately. Then,an observation value based attitude controller was designed to make the real angular velocity exponential converge to virtual angular velocity. Analysis results show that, the dual-loop attitude tracking controller can satisfy the constraints of bounded angular velocity and control saturation,present higher tracking accuracy and robustness.Numerical simulation results validate the robustness and effectiveness of the dual-loop attitude tracking controller.