The Abrupt Wing Stall (AWS) at moderate Angle-of-Attacks (AoA) and transonic flight conditions can result in uncommanded lateral motions such as heavy wing, wing drop and wing rock that degrade handling qualities, mission performance and safety of flight for the aircraft. This phenomenon caused by asymmetric wing flows makes it difficult to perform precision tracking or maneuvering in the transonic flight envelope. According to the previous research results, this substantial phenomenon has occurred in a large number of the fighter aircraft programs, typically at the early flight test development stage, and a lot of budgets and efforts are required through the development period of the aircraft. To compensate for this drawback, Free-To-Roll (FTR) wind tunnel test is adopted as a method to identify the uncommanded lateral motions of the aircraft and improve the flight characteristics at the configuration design stage. However, using only the existing control methods such as the feed-forward control methods as well as the configuration design can reduce limitedly the uncommanded lateral motion. Besides, the feedback control methods using optimal control, adaptive and neural network control which do not provide a deterministic solution are limited to obtain the airworthiness certification. This paper presents a new design approach in which uncommanded lateral motions of the aircraft can be reduced even more than the existing methods. That is the additional augmentation control method, using angular acceleration measurement, that improves the flight characteristics using a feedback control technique based on the Incremental Nonlinear Dynamic Inversion (INDI). To evaluate the performances of the proposed control method, we perform the frequency-domain linear analysis and time-domain numerical simulations based on the mathematical model of advanced trainer aircraft. The evaluation result reveals that the proposed control method reduces effectively uncommanded lateral motions and improves the handling qualities of the aircraft.

中文翻译：

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改进战斗机无指令横向运动的飞行控制律的发展

中等迎角 (AoA) 和跨音速飞行条件下的突然机翼失速 (AWS) 会导致无指令的横向运动，例如沉重的机翼、机翼下垂和机翼晃动，从而降低操纵质量、任务性能和飞行安全性飞机。这种由不对称机翼流动引起的现象使得在跨音速飞行包线中难以进行精确跟踪或机动。根据以往的研究结果，这种实质性的现象已经出现在大量的战斗机项目中，通常是在早期的飞行测试开发阶段，在飞机的整个开发阶段都需要大量的预算和努力。为了弥补这个缺点，在构型设计阶段，采用自由滚转（FTR）风洞试验作为识别飞机非指令横向运动并改善飞行特性的方法。然而，仅使用现有的控制方法如前馈控制方法以及配置设计可以有限地减少非指令横向运动。此外，使用最优控制、自适应和神经网络控制的反馈控制方法不能提供确定性解决方案，仅限于获得适航审定。本文提出了一种新的设计方法，在该方法中，可以比现有方法更多地减少飞机的非指令横向运动。即附加增强控制方法，使用角加速度测量，使用基于增量非线性动态反演 (INDI) 的反馈控制技术改善飞行特性。为了评估所提出的控制方法的性能，我们基于先进教练机的数学模型进行频域线性分析和时域数值模拟。评估结果表明，所提出的控制方法有效地减少了非指令横向运动，提高了飞机的操纵质量。