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The paper briefly presents two simulation models which describe the motion and dynamics of biaxial vehicles: a medium class car and 12 tons truck. The road surface may be even or uneven. The main models may be divided into coupled submodels. Their equations of motion can be derived separately. The programs can be run even on personal computers. The models are experimentally verified on even roads for typical manoeuvres recommended by ISO. The paper shows mainly the results of experimental evaluation of simulation models. It also presents steering system submodel in more detail. Its combination with other submodels describe small car motion and dynamics including the influence of steering system freeplay and dry friction.

The authors measure and simulate the vehicle motion in situations where typical defensive maneuvers in road traffic are being carried out, namely straight braking, double lane-change (overtaking), and ramp input on the steering wheel. They reproduce the vehicle motion (i.e. velocity, vehicle's C.G. trajectory and yaw angle) by using real records or by the simulated electronic data recorder (EDR) outputs. Thus, they operate in a way that is similar to that employed by forensic experts who analyze the EDR outputs. The employed method provides means of comparing the real or simulated exact values of velocity and of the vehicle's C.G. trajectory to the readings obtained by integrating the EDR outputs simulation. Estimation of the error, produced by the expert employing the EDR outputs, can be made in this way. The results show a possibility of occurrence of significant values of the error for simplified version of the device.

The paper presents a model derived for real time simulation. It has been applied in low-cost PC-based autoPW driving simulator built at the University of Technology, Faculty of Transportation, Poland. The following assumptions have been done: even, horizontal road surface, no vertical, pitch and roll vibrations of the body as well unsprung masses. The normal reactions of the road are described in quasi-static way. Compliances of steering system as well as description of six aerodynamic drag components are taken into account. The tire model is based on HSRI-UMTRI model with addition of aligning moment description. The model was experimentally verified.

The authors simulate the vehicle motion in situations where typical defensive maneuvers in road traffic are being carried out, namely straight braking, singular lane-change and “J-turn”. They reproduce the vehicle motion (i.e. velocity, vehicle's C.G. trajectory and yaw angle) by using the simulated “black box” outputs. Thus, they operate in a way that is similar to that employed by forensic experts who analyze the “black box” outputs. The employed simulation method provides means of comparing the simulated exact values of velocity and of the vehicle's C.G. trajectory to the readings obtained by integrating the “black box” outputs simulation. Estimation of the error produced by the expert employing the “black box” outputs can be made in this way. The body pitch and roll are sources of longitudinal and lateral acceleration recording errors because a gravitational acceleration component for the respective direction is added in simplified version of the device.