可重复使用飞行器再入姿态的区间二型自适应模糊滑模控制设计

针对具有强非线性、多变量耦合特性的可重复使用飞行器（RLV），同时考虑模型参数不确定性和外界干扰对飞行器再入姿态跟踪的影响，提出了一种基于区间二型自适应模糊滑模的姿态控制方法。首先，建立飞行器再入动态模型，并基于反步思想将控制模型转化为姿态角和角速率相关子系统。其次，将模型参数不确定性和外界干扰视作子系统非线性项的一部分。再次，采用区间二型模糊系统逼近子系统非线性项，并结合自适应技术和滑模控制方法分别设计虚拟控制量和实际控制量。此外，引入一阶低通滤波器用以处理子系统虚拟控制律。通过Lyapunov方法的分析证明了闭环控制系统的稳定性，且飞行器姿态跟踪误差可收敛于原点附近的小邻域。最后，利用飞行器的数值仿真验证了所设计控制方法能有效跟踪飞行器参考指令，且对外界干扰有较强的鲁棒性。 

Interval type-2 adaptive fuzzy sliding mode control design of reentry attitude for reusable launch vehicles

Considering the attitude tracking problem for reusable launch vehicles (RLVs) during reentry phase with high nonlinear and multi-variable coupling characteristics in the presence of parameter uncertainties and external disturbances, an interval type-2 adaptive fuzzy sliding mode based attitude control method is proposed in this paper. Firstly, the dynamic model for the RLV is developed, which is further transformed into attitude angle and angular rate subsystems using backstepping method. Secondly, the parameter uncertainties and external disturbances of the RLV model are regarded as part of the nonlinear terms of the subsystems. Thirdly, the nonlinear terms of the subsystems are approximated by the interval type-2 fuzzy system, while the virtual control signal and the actual control signal can be obtained respectively by combining the adaptive technique and sliding mode control method. Besides, the first-order low-pass filter is used to deal with the virtual control law of subsystem. The stability of the closed-loop control system is guaranteed via Lyapunov theory and the attitude tracking error can converge to a small neighborhood around the origin. Finally, the numerical simulation on the reentry vehicle is conducted to verify that the developed control method can track the reference commands effectively and have strong robustness again external disturbances.