  Unmanned ground vehicle obstacle crossing generally relies on two strategies:
(i) applying a wheel torque for climbing and (ii) modifying the vehicle shape
by using a wheel-leg or wheel-paddle to lift the wheel on top of the obstacle.
However, most of those strategies sacrifice speed in order to have a longer
contact duration between the wheels and the obstacle. This paper investigates
the behaviour of a 4WD high-speed vehicle while crossing a step obstacle using
a design of experiment (DoE). A 3D multibody vehicle model is equipped with a
novel 2-DoF suspension system, which horizontal damping coefficient is modify
to dampen wheel motion in longitudinal and vertical directions in relation to
the chassis, for a given speed and obstacle height. The DoE results allow to
propose a novel high-speed obstacle crossing strategy based on three metrics:
(i) the kinetic energy variation of the vehicle, (ii) the contact duration
between the wheel and the obstacle, and (iii) the pitch rate at the start of
the ballistic phase. Experimental function are proposed to be able modify these
metric in real time.
