Modeling of Pitch and Bounce Motions of Single-Passenger Off-Road Vehicles

A four degree of freedom model of a single passenger off-road vehicle (ATV) is presented. A designer may use the model to study the effects of spring stiffnesses, damping coefficients in bump and jounce, tire stiffnesses, center of gravity placement, and vehicle moment of inertia on the vertical bouncing and pitching motion of the sprung and unsprung masses over any terrain profile. In order to isolate the effects of the rider, he is modeled as if in the posting position as a mass concentrated at the foot pegs.