A New Vibrational Control System in Nature: Flapping Flight
A New Vibrational Control System in Nature: Flapping Flight
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DOI：
10.2514/6.2019-1417
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发表时间：
2019-01
期刊：
影响因子：
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通讯作者：
H. Taha;M. Kiani
中科院分区：
文献类型：
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作者：
H. Taha;M. Kiani
振动控制是一种通过应用高振幅、高频振荡输入的开环稳定技术。平均理论已成为设计振动控制系统的标准技术。但是，它规定的振荡频率太高，实际上可能不可行。因此，尽管振动控制非常鲁棒和优雅（无反馈稳定），但在实际应用中很少使用。唯一著名的例子是卡皮察钟摆；倒立摆的枢轴受垂直振荡的影响。倒立摆的不稳定平衡由于枢轴的高频振荡而趋于渐近稳定。在本文中，我们提供了一种新的振动控制系统。扑翼飞行动力学。扑翼飞行是一个丰富的动力系统，其代表模型通常是非线性的、时变的、多体的、多时间尺度的动力系统。在过去的二十年中，使用直接平均，在扑翼飞行动力学界已经达成共识，昆虫在悬停平衡时不稳定是由于缺乏俯仰刚度。在这项工作中，我们对扑翼飞行的时间周期动力学进行了高阶平均，以显示由于驱动气动力的振荡而产生的振动控制机制。我们还在具有前向平移和俯仰运动两个自由度的扑动装置上实验证明了这种现象。发现扑翼微型飞行器的时间周期动力学在超过一定阈值时是自然稳定的（无反馈）。此外，如果平均气动推力是由螺旋桨在保持机翼固定在其平均位置时以恒定速度旋转产生的，则没有观察到稳定。因此，可以得出结论，在高频率下，扑翼系统的稳定性是由于驱动气动力的振荡造成的，因此，扑翼飞行确实具有振动稳定性。
Vibrational control is an open loop stabilization technique via the application of highamplitude, high-frequency oscillatory inputs. The averaging theory has been the standard technique for designing vibrational control systems. However, it stipulates too high oscillation frequency that may not be practically feasible. Therefore, although vibrational control is very robust and elegant (stabilization without feedback), it is rarely used in practical applications. The only well-known example is the Kapitza pendulum; an inverted pendulum shose pivot is subject to vertical oscillation. the unstable equilibrium of the inverted pendulum gains asymptotic stability due to the high-frequency oscillation of the pivot. In this paper, we provide a new vibrational control system from Nature; flapping flight dynamics. Flapping flight is a rich dynamical system as a representative model will typically be nonlinear, time-varying, multi-body, multi-time-scale dynamical system. Over the last two decades, using direct averaging, there has been consensus in the flapping flight dynamics community that insects are unstable at the hovering equilibrium due to the lack of pitch stiffness. In this work, we perform higher-order averaging of the time-periodic dynamics of flapping flight to show a vibrational control mechanism due to the oscillation of the driving aerodynamic forces. We also experimentally demonstrate such a phenomenon on a flapping apparatus that has two degrees of freedom: forward translation and pitching motion. It is found that the time-periodic dynamics of the flapping micro-air-vehicle is naturally (without feedback) stabilized beyond a certain threshold. Moreover, if the averaged aerodynamic thrust force is produced by a propeller revolving at a constant speed while maintaining the wings stationary at their mean positions, no stabilization is observed. Hence, it is concluded that the observed stabilization in the flapping system at high frequencies is due to the oscillation of the driving aerodynamic force and, as such, flapping flight indeed enjoys vibrational stabilization.