Experimental Modeling of Vertical Dynamics of Vehicles with Controlled Suspensions 2004-01-1546

In the paper, identification of vertical dynamics of vehicles with controlled suspensions is considered. Identification is performed from experimental data measured on a four-poster bench test of a segment C car, equipped with a CDC-Skyhook dampers control system. Vertical displacements at tires are imposed, related to different types of road profiles at different constant speeds and the following front and rear variables have been measured: chassis accelerations, wheels accelerations, chassis-wheel displacements, chassis-road displacements and control currents of the dampers. A nonlinear model in regression form is identified, having the road profile and damper control currents as inputs and chassis and wheels accelerations as outputs. The model is identified by means of a Set Membership structured identification method, which takes advantage of physical information on the structure of the system, decomposing the system in five subsystems: one represents the chassis and engine and the other ones represent the front and rear suspensions and wheels-tires. The overall high-dimensional identification problem is reduced to the identification of lower dimensional subsystems and to the estimation of their interactions and a recently proposed iterative scheme is used for its solution. A quite satisfactory overall model has been obtained, whose accuracy is documented by simulating the system with road profiles and damper control currents not used for the identification.