On the identification of vehicle longitudinal dynamics

A functional model of vehicle-propulsion system/roadway-interface dynamics is specified, and a model-matching procedure, wherein closed-loop vehicle longitudinal controllers are employed, is detailed for identifying the parameters of this model. This procedure was employed to determine the longitudinal dynamics of a dual-mode test vehicle. The derived dynamics, which are highly velocity dependent, were validated in a series of full-scale tests in which large-signal inputs were employed. The methodology employed and the general nature of the results, especially the substantial velocity dependence, appear applicable to a wide range of rubber-tired vehicles. The failure to adequately account for such dependence, which arises from the properties of the propulsion system and the propulsion system/roadway interface, could result in a design with little basis in reality.