Investigation of the Behavior of Adaptively Controlled Platoons with Unmodeled Loads

Regarding the behavior of vehicles in roadway traffic typical classes can be identified for individually driven cars showing "collective saturation" features as the capacities of the road are almost maximally utilized, and for the organized group of cars or lorries operating as "platoons". The present paper is devoted to modeling and analyzing the behavior of a platoon that is formed of semi-automated vehicles and behaves like a virtual train. Each member has local controller trained for keeping a safe tracking distance between itself and the preceding member of the group. In the model investigated the connection between the vehicles acts like an elastic spring with the distinction that no "reaction forces" are applied: the (n + 1)^th member\´s motion is influenced by that of the nth member but the members do not affect the motion of the preceding ones. The aim is to guarantee the possible smoothest motion for the last element of the train that may be followed by various participants of the road communication whose driving comfort has to be kept in mind. For this purpose in this paper the first member\´s motion is directly controlled while the other members trail their preceding cart according to this automated tracking mechanism. The carts are approximately modeled as rigid bodies while their loads are represented by masses connected to the appropriate carts by elastic springs having dynamic friction. The dynamic interaction between the loads and the carts are not modeled by the controllers and the main task of the adaptive control is to compensate the effects of the modeling errors and that of the abandoned loads. It is shown via computer simulation that the novel, geometrically interpreted adaptive control elaborated at Budapest Tech in the past few years can successfully solve this complicated task and can reduce the jogging of the load of the carts.