On-ground Aircraft Modeling for Advanced Braking Control System Design

An original simplified 6-DOF on-ground aircraft model is developed, with the intent of providing an efficient means for novel braking control law synthesis. The proposed modeling approach consists of including the entire set of contributing dynamics, during aircraft high-speed braking, scaling the level of complexity and fidelity in function of the dominance of each physical phenomenon described. To this end, simplistic aerodynamic and propulsive models are coupled with a very detailed landing gear mathematical description, including shock-absorber, wheel-ground interaction and tire dynamics. Different modeling techniques are employed, such as analytical, parametric or tabulated models, depending on the subsystem nature and the related available data. The complete aircraft on-ground model is finally validated against a fully nonlinear multi-body simulator available at Safran Landing Systems. The proposed approach demonstrates high fidelity behavior, being capable of capturing critical phenomena such as load transfer between landing gear struts and wheel longitudinal-vertical dynamic coupling, while remaining simple and suitable for a control design purpose. Pertinent results are provided and discussed at the end of the paper.