Bifurcation and stability analysis of aircraft turning on the ground

During ground maneuvers a loss of lateral stability due to the saturation of the main landing gear tires can cause the aircraft to enter a skid or a spin. The lateral stability is governed not only by aspects of the gear design, such as its geometry and tire characteristics, but also by operational parameters: for example, the weather and taxiway condition. In this paper, we develop an improved understanding and new presentation of the dynamics of an aircraft maneuvering on the ground, ultimately aimed at optimization and automation of ground operations. To investigate turning maneuvers, we apply techniques from dynamic systems theory to a modified version of a nonlinear computer model of an A320 passenger aircraft developed by the Landing Gear Group at Airbus in the United Kingdom. Specifically, we present a bifurcation analysis of the underlying solution structure that governs the dynamics of turning maneuvers with dependence on the steering angle and thrust level. Furthermore, a detailed study of the behavior when lateral stability is lost focuses on how the tire saturation at different wheel sets leads to qualitatively different types of overall behavior. The presented bifurcation diagrams identify parameter regions for which undesirable behavior is avoidable, and thus they form a foundation for defining the safe operating limits during turninv maneuvers.