This article examines the fundamental aspects of controlling ground resonance in rotorcraft equipped with actively controlled landing gear. Ground resonance is a mechanical instability affecting rotorcraft on the ground. It occurs at certain rotor speeds, where the lead–lag motion of the rotor couples with the motion of fuselage creating a self-excited oscillation. Typically, passive or semi-active lag dampers are used to avoid instability; however, these are undesirable from a design and maintenance perspective. Innovations in active landing gear for rotorcraft, such as articulated robotic legs, have provided an alternate approach to avoid the instability, eliminating the need for lag dampers with respect to ground resonance. This article extends classic ground resonance to include movable landing gear and identifies key physical parameters affecting dynamic behavior. Applying LQ optimal control to this model, it is shown that ground resonance instability can be eliminated using active landing gear as the control mechanism, even when there is no lag damping present in the rotor. In addition, while superior performance is achieved when landing gear movement can occur both longitudinally and laterally, it is still possible to stabilize ground resonance with inputs in a single direction, albeit with reduced performance.

本文研究了在配备主动​​控制起落架的旋翼机中控制地面共振的基本方面。地面共振是一种影响地面旋翼机的机械不稳定性。它发生在某些旋翼速度下，旋翼的超前-滞后运动与机身运动相结合，产生自激振荡。通常，被动或半主动滞后阻尼器用于避免不稳定；然而，从设计和维护的角度来看，这些都是不可取的。旋翼机主动起落架的创新，例如铰接式机器人腿，提供了一种避免不稳定的替代方法，消除了对地面共振滞后阻尼器的需要。本文将经典的地面共振扩展到包括可移动起落架，并确定影响动态行为的关键物理参数。将 LQ 优化控制应用于该模型，表明使用主动起落架作为控制机制可以消除地面共振不稳定性，即使旋翼中不存在滞后阻尼。此外，虽然当起落架可以纵向和横向移动时实现了卓越的性能，但仍然可以通过单一方向的输入稳定地面共振，尽管性能有所降低。