Optimization of the suspension damping parameters of a sport motorcycle

In this paper a handling-oriented procedure for the optimization of the suspension damping parameters of a passively suspended sport motorcycle is presented. The suspension systems installed nowadays in this kind of vehicles make it possible to fine tune the damping characteristics through a wide range of adjustments, so that the amount of force delivered for low and high displacement speed, in both compression and rebound configurations, can be independently set by the user. Nevertheless, the optimal choice of suspension tuning parameters is a difficult task, normally affecting the vehicle dynamic behavior and its handling characteristics, and no automatic, model-based procedures have been developed and adopted in practice for this purpose. Hence an optimization function is proposed, starting from the simulation results during standard maneuvers. These maneuvers have been modeled by means of a planar, four degrees of freedom, lumped parameters vehicle model, where the front suspension non-linearity has been taken into account. The experimental damping force versus speed curves have been approximated by a non-parametric b-spline piecewise function. The effects of all of the tuning control parameters and the dry friction are shown. The vehicle performance is then estimated by means of an objective function based on the minimization of the fluctuating component of the vertical front tire-ground force, allowing the tire to maximize the friction contact actions, i.e. to maximize the vehicle’s ability to accelerate.