Dynamic modelling of the double wishbone motor-vehicle suspension system

In this paper the dynamic analysis of the double wishbone motor-vehicle suspension system using the point-joint coordinates formulation is presented. The mechanical system is replaced by an equivalent constrained system of particles and then the laws of particle dynamics are used to derive the equations of motion. Due to the presence of large number of geometric and kinematic constraints the velocity transformation approach is used to eliminate some constraints. The equations of motion in terms of the Cartesian coordinates of the particles are transformed to a reduced set in terms of relative joint variables by defining suitable generalized speeds. The resulting differential-algebraic equations in terms of the joint variables are equal to the number of degrees of freedom of the whole system plus the number of cut-joint constraints corresponding to cut of kinematical closed loops. Use of both the Cartesian and relative joint variables produces an efficient set of equations without loss of generality. The chosen suspension includes open and closed loops with quarter-car model.