低空风切变下基于NDI-PID的飞机进近控制律设计

NDI-PID Based Control Law Design for Aircraft Approaching in Low-Altitude Windshear

针对飞机在进近过程中遭遇低空风切变后的轨迹控制问题,通过建立较真实的风切变工程化模型和飞机非线性数学模型,应用奇异摄动理论对飞机状态变量进行时标划分,采用非线性动态逆方法设计了快、慢状态子系统的控制律以及外回路制导系统的控制律;并引入PID控制,补偿由风切变和其他外界因素引起的飞机气动参数摄动带来的系统逆误差,从而消除系统稳态误差,实现对飞机进近轨迹的有效保持;最后进行了数值仿真验证,结果表明,采用动态逆与PID相结合的控制方法,能使系统具有较好的动态特性和鲁棒性,能有效抵抗一定强度的风切变干扰。

The trajectory control of aircraft when encountering low-altitude windshear in approaching is studied. A realistic engineering model of windshear and a nonlinear mathematical model of aircraft are established. Singular perturbation theory is applied to divide the dynamic system into several simple subsystems, and the Nonlinear Dynamic Inversion （NDI） method is employed for designing the control law for slow-state/fast-state subsystem and guidance system of outside loop. PID control method is also adopted for compensating the system inversion error arising from the perturbation of aircraft aerodynamic parameters caused by windshear and other exterior factors, which effectively eliminates steady state error of the system and keep effective control to the flight path of aircraft approaching. Finally, the simulation results indicate that the proposed NDI-PID controller has good dynamic characteristics and robustness, which can effectively resist the windshear interference with certain strength.