考虑多边界状态约束的飞翼布局无人机姿态控制

Attitude control of fly wing UAV with multi-boundary state constraints

以大展弦比飞翼布局无人机为研究对象,针对强扰动环境下多边界状态约束时的飞行姿态控制问题,提出一种指令-控制律联合限制的全状态约束控制方法。该控制方法分别独立设计了指令边界限制器、过渡指令产生器和指令跟踪控制器3个部分。首先,基于无人机动力学特性设计的指令边界限制器,利用无人机的各个状态边界来限制姿态控制器的指令,实现了将非受控状态的约束问题转化为受控状态的约束问题;其次,基于"安排过渡过程"的思想并考虑约束限制环节,设计了过渡指令产生器,为无人机在线生成从当前姿态到期望跟踪姿态的过渡指令;最后,基于障碍Lyapunov函数和扩张状态观测器,设计了指令跟踪控制器,使无人机能够克服干扰且快速稳定地跟踪过渡指令。通过采用Lyapunov稳定性理论分析,该控制方法能够保证姿态跟踪误差收敛有界,且始终处于给定区间内部。仿真结果表明,该控制方法能够保证无人机飞行状态在不超出约束边界的同时,实现对姿态指令的准确跟踪。

To solve the flight attitude control problem under multi-boundary state constraints and strong disturbance, a joint command-control law limiting full state constraint control approach is proposed, with a high-aspect-ratio flying wing UAV as the research model. This control approach consists of three independent parts, command limiter, reference generator and command tracker. Firstly, based on the aircraft dynamic characteristics, the command limiter utilizes each state bound to restrict attitude command. In this way, the constraint problem of non-controlled states is converted into a constraint problem of controlled states. Secondly, the reference generator provided a command trajectory from the current attitude to the desired attitude. This online process is achieved according to the idea of ＂transition process arranging＂ and considering the constraints. Finally, the command tracker is designed based on barrier Lyapunov function and extended state observer, which enable the UAV overcoming disturbance and tracking command trajectory quickly and stably. The stability is analyzed by means of Lyapunov theory. Attitude tracking error is proved to be bounded-convergent and always remain in the given region. Simulation results show that UAV tracks the desired attitude command accurately. Moreover, the established controller can prevent flight states from exceeding limitation.