考虑扰流的舰载机终端进场线性模型

回收舰载机需要精确的终端路径和姿态控制,舰载机线性小扰动模型是这一阶段系统分析和控制器设计的必要工具,它需要足够准确地描述在主要操纵输入和进场路径大气紊流作用下舰载机的动态特性。首先使用代数线性化方法建立舰载机终端进场纵向运动的小扰动模型,仿真证明该模型能精确描述无风条件下进场舰载机对控制指令的响应,但通常的建模气流扰动影响的方法不能正确反映舰尾大气紊流对舰载机进场速度的干扰。针对该问题,重点研究了垂向风引起的进场舰载机轨迹方向上的力瞬变,提出了量化舰载机地速扰动的表达式以优化线性模型参数。最后,通过完成舰载机动力学模型在不同风场下的开环仿真以及在舰尾流场中的终端进场闭环仿真,验证了改进的线性模型的有效性,表明它适用于复杂流场下着舰控制系统的性能分析和设计。

Linearized carrier-based aircraft model in final approach phase with air turbulence considered

Recovery of a carrier-based aircraft demands precise terminal control of position and attitude. For system analysis and controller design in this phase, it is crucial to obtain an accurate linear small-perturbation model of the aircraft. The linear model needs to be precise enough to describe responses of the aircraft to not only the major maneuvers imposed, but the air turbulence around the approach path. In this paper, a linear perturbed model for the longitudinal final approach dynamics of an example carrier-based aircraft is established with an algebraic linearization method. Simulated tests indicate that the precision of the model is sufficient in depicting the responses of the aircraft to coordinated control inputs in calm air environment, but deficient in analyzing the approach velocity disturbed by carrier air-wake because of employing a conventional modeling method to introduce the air turbulence effects. For the purpose, the attention is firstly turned to the researches of the force transient that is presented in the course direction of the aircraft and induced by a vertical gust of wind. Then, an expression to quantify the velocity change of the aircraft is proposed, thereby optimizing the relevant parameters of the derived linear model. At last, the validity of the modified linear model is verified by performing the simulations of the linear and the nonlinear aircraft models in the open-loop state with different wind profiles involved, as well as in the closed-loop final approach state with carrier air-wake disturbance engaged. The results show that the improved linear model is applicable to the control system analysis and design of the aircraft carrier landing in complex airflow fields.