Nonlinear aircraft ground dynamics

The dynamics of aircraft manoeuvring on the ground is nonlinear due to nonlinearities in tyres, in other landing gear components, and potentially in the aerodynamics of the airframe. Existing linear approaches are effective in respect of local behaviour around specific operating conditions, but in order to evolve a global understanding of the dynamics of an aircraft on the ground other techniques are needed. We demonstrate here that bifurcation analysis and continuation methods can be used for the purpose of building up a global stability diagram in a computationally efficient manner. Specifically, we perform a continuation study of a nonlinear tricycle model implemented in the SimMechanics environment and then coupled to the continuation software AUTO. Our study yields unexpected phenomena, namely a complicated structure of branches with hysteresis loops and instabilities leading to oscillations and even chaotic dynamics.