基于非线性L1自适应动态逆的飞行器姿态角控制
Attitude control of flight vehicle based on a nonlinear L1 adaptive dynamic inversion approach

针对常规动态逆控制器不能有效抵消系统中的不确定性这一缺点, 提出了一种非线性L1自适应动态逆控 制方法. 该方法能够克服常规动态逆的不足, 在保证系统鲁棒性的前提下, 提升飞行器姿态角控制效果. 首先, 采用 时标分离原理, 将姿态角控制系统分为内外两个回路: 外回路采用常规动态逆控制器, 用于姿态角的跟踪控制; 内 回路采用非线性L1自适应控制器, 用于角速率的控制. 其中, L1自适应控制器由静态反馈控制器和自适应控制器组 成: 静态反馈控制器通过状态反馈实现, 用于保证内回路的稳定和具有期望的闭环特性; 自适应控制器由状态观测 器、自适应律和控制律组成, 用于抵消系统中的不确定性. 其次, 对所提控制方法的稳定性进行了分析, 结果证明了 该控制方法能够保证内回路的稳定和外回路的误差有界. 最后, 在综合考虑多种不确定性的情况下, 将本文提出的 非线性L1自适应动态逆控制方法用于某无人飞行器姿态角控制, 仿真结果验证了该控制方法的有效性和鲁棒性.
Since the conventional dynamic inversion (DI) controller cannot cancel the system uncertainties efficiently, a nonlinear L1 adaptive dynamic inversion control approach is proposed. This approach is able to overcome the disadvantage of conventional DI and improve the control effects with sufficient robustness. Firstly, the attitude control system is divided into outer loop and inner loop based on the time-scale separation principle. The DI controller is employed to track attitude angles in the outer loop; a nonlinear L1 adaptive controller is employed to control angular rates in the inner loop. The L1 adaptive controller is composed of the static feedback controller and the adaptive controller. The static feedback controller, which is achieved by the state feedback, is used to guarantee stability and expected closed-loop performance of the inner loop; the adaptive controller, which contains state observer, adaptive law and control law, is used to cancel the uncertainties of system. Then, the stability of the proposed approach is analyzed whose results show the proposed controller is able to guarantee the stability of the inner loop and error boundedness of the outer loop. Finally, considering multiple uncertainties, the proposed nonlinear L1 adaptive dynamic inversion approach is applied to the attitude control of a certain unmanned flight vehicle. Simulation results show the effectiveness and robustness of the control approach.