扑翼的变刚度设计及其对升力和推力的影响

为提高扑翼飞行器的升力和推力以提高其飞行性能，运用生物扑翼的仿生原理，研究扑翼飞行器的扑翼升力和扑翼推力随扑翼刚度变化的机理。借鉴"变刚度关节机构和平面转动冗余并联机构通过调节张力改变刚度"这一机构学原理，运用变刚度关节机构相互串联实现扑翼在扑动方向上变刚度，同时运用平面转动冗余并联机构实现扑翼在扭转方向上变刚度。建立扑翼的扑动关节刚度和扭转机构刚度随预张力变化的模型，并通过实验和仿真验证扑翼扑动关节刚度和扭转机构刚度随预张力的变化。研究扑翼的升力和推力与扑翼刚度之间的关系，验证了通过调节扑翼刚度匹配其扑动频率可以提高扑翼的升力和推力。

Variable stiffness design of flapping wings and its effects on lift and thrust

To improve lift and thrust and hence flight performance of flapping-wing air vehicles (ornithopters), this study examines the mechanism of both the lift and thrust changing with the stiffness of flapping wings by applying the bionic principles of biological wings. Based on the principle that the stiffness of both variable-stiffness joint mechanisms and Redundantly Planar Rotational Parallel Mechanisms (RPRPM) can be modulated by adjusting the pretensions, a stiffness variation on the flapping direction is achieved by variable-stiffness joints connected to each other. The rotating stiffness modulation of the wings can be replicated by applying RPRPM. The stiffness variation models of the flapping joints and the rotating mechanism with pretensions are established, and then validated by experiments and simulation. The relationships between both the lift and the thrust of the wing and the stiffness of the wing are studied, and it is validated that the lift and the thrust of the wing can be improved by modulating the stiffness of the wing to match the flapping frequency.