Yu Zelong, Zhang Jingjuan, Wang Xueyun
School of Instrumentation Science and Opto-Electronics Engineering, Beihang University, Beijing 100191, China.
School of Aeronautic Science and Engineering, Beihang University, Beijing 100191, China.
Sensors (Basel). 2023 Jan 4;23(2):574. doi: 10.3390/s23020574.
In this paper, a control method of a novel tilt-rotor UAV with a blended wing body layout is studied. The novel UAV is capable of vertical take-off and landing and has strong stealth capabilities that can be applied to carrier-borne reconnaissance aircraft. However, the high aspect ratio of blended wing body UAVs leads to a wingtip or oar-tip touchdown problem when adopting the conventional position-attitude control (CPAC) scheme with a large crosswind disturbance. Moreover, when the UAV is subject to interference during reconnaissance, aerial photography, and landing missions, the conventional scheme cannot provide both attitude stability and track accuracy. First, a direct thrust vectoring control (DTVC) scheme is proposed. The control authority of the rotor tilt mechanism was added to enable the decoupling of the attitude and trajectory and to improve the response rate and response bandwidth of the flight trajectory. Second, considering the problems of strong couplings and parameter uncertainties and the nonlinear features and mismatched perturbations that are inevitable in the tilt-rotor, we designed a robust UAV controller based on the backstepping sliding mode control method and determined the stability of the control system through the Lyapunov function. Finally, in the case of crosswire interference during vertical takeoff and landing and the aerial photography missions of the UAV, the numerical simulation of the CPAC scheme and the DTVC scheme was carried out, respectively, and the Monte Carlo random test method was introduced to conduct the statistical test of the landing accuracy. The simulation results show that the DTVC scheme improves the landing accuracy and speed compared to the CAPC scheme and decouples the position control loop from the attitude control loop, finally enabling the UAV to complete the flight control in the VTOL phase.
本文研究了一种具有融合翼身布局的新型倾转旋翼无人机的控制方法。这种新型无人机能够垂直起降，具有很强的隐身能力，可应用于舰载侦察机。然而，融合翼身无人机的高展弦比在采用具有大侧风干扰的传统位置姿态控制（CPAC）方案时会导致翼尖或桨尖触地问题。此外，当无人机在侦察、航拍和着陆任务中受到干扰时，传统方案无法同时提供姿态稳定性和轨迹精度。首先，提出了一种直接推力矢量控制（DTVC）方案。增加了旋翼倾转机构的控制权限，以实现姿态和轨迹的解耦，并提高飞行轨迹的响应速率和响应带宽。其次，考虑到倾转旋翼中不可避免的强耦合、参数不确定性以及非线性特性和失配扰动问题，我们基于反步滑模控制方法设计了一种鲁棒无人机控制器，并通过李雅普诺夫函数确定了控制系统的稳定性。最后，在无人机垂直起降和航拍任务中存在交叉干扰的情况下，分别对CPAC方案和DTVC方案进行了数值模拟，并引入蒙特卡洛随机测试方法对着陆精度进行了统计测试。仿真结果表明，与CAPC方案相比，DTVC方案提高了着陆精度和速度，将位置控制回路与姿态控制回路解耦，最终使无人机能够在垂直起降阶段完成飞行控制。
