The dynamical behaviour of a four-wheeled off-road vehicle is analysed by the use of a seven degrees-of-freedom model for two loading conditions - loaded and unloaded - and for two different types of road - asphalt and pavement. To find the characteristics of the suspension elements, stochastic optimal linear control theory is used through the minimization of the performance index whose constituent parts are: vehicle vertical acceleration (comfort), suspension working space (structural limitation), road holding (safety) and the control force (technical cost limitation). The influence of these parts in the performance index is related through the weighting constants. The performance of the passive, active with full state and limited output feedback systems is compared when the vehicle is driving on a random road. (A)
Abstract