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The driving simulator (DS) developed by Toyota Motor Corporation simulates acceleration using translational (XY direction) and tilting motions. However, the driver of the DS may perceive a feeling of rotation generated by the tilting motion, which is not generated in an actual vehicle. If the driver perceives rotation, a vestibulo-ocular reflex (VOR) is generated that results in an unnecessary correction in the driver's gaze. This generates a conflict between the vestibular and visual sensations of the driver and causes motion sickness. Although such motion sickness can be alleviated by reducing the tilting motion of the DS, this has the effect of increasing the amount of XY motion, which has a limited range. Therefore, it is desirable to limit the reduction in the tilting motion of the DS to the specific timing and amount required to alleviate motion sickness. However, the timing and extent of the VOR has yet to be accurately identified.

With the progress of super computers in recent years, a number of studies on “Computational Fluid Dynamics” (CFD) have been carried out, and various schemes for Navier-Stokes equations have been presented. Similar methods have also been applied to automotive engineering - aerodynamics, for exampre - in order to determine flow phenomena. In this paper, the application of numerical simulations to the flow cavitation that occurs in some part of orifices in the vehicle hydraulic system, will be discussed. Authors have developed a CFD program for the clarification of flow phenomena in such orifices. Using the relationship between calculated results and measured results of noise levels in such orifices, a new method for estimation of the occurrence of flow cavitation has also been developed. As a result, a new orifice configuration capable of preventing the cavitation has been designed.

We have developed a vehicle test system called the Vehicle Dynamics Simulator (VDS). The system measures the handling characteristics in a transient state in the laboratory. The automobile suspensions are moved as on a road with the machine providing relative motion by force transducer platform beneath each tire. The detailed measurements of transitive motions and forces given to the wheel clarify the kinematics and compliance characteristics contributed to the good handling performance and stability. This paper presents the system introduction and the results of analyzing the suspensions characteristics by the new analytical technique for breaking down into a variety of compliance components in a transient state.

A number of active safety systems are already developed to support drivers’ decision and action to help avoid accidents, but further enhancement of those active safety systems cannot be accomplished without increasing our understanding on driver behaviors and their interaction with vehicle systems. For this reason, a state-of-art driving simulator (DS) has been developed that creates very realistic scenarios as a means of realizing these requirements. The DS consists of a simulator cabin, turntable (inside the dome), a 6-DOF hexapod system, shakers (vehicle vertical vibration actuators), and a motion system capable of moving 35 meters longitudinally and 20 meters laterally. The system is also capable of projecting images of actual city streets and highways onto a 360° spherical screen inside of the dome. As a result, the DS is able to reproduce a driving environment that is very similar to real driving.

On diesel vehicles, we frequently experience the phenomenon that low frequency fore and aft vibration of a vehicle, occurs at acceleration, does not decline in amplitude easily and rather increases finally. The phenomenon has recently attracted great concern in driveability problems on diesel vehicles. This phenomenon can not be explained well by the simple torsional vibration model of the powertrain with one node, which has been used so far successfully to analyze low frequency fore and aft vibration of a vehicle. So, we have assumed that the undamped vibration occurs through the interaction of the engine and the powertrain. Taking this interaction into consideration, we have constructed a simulation model, with which the undamped vibration can be simulated accurately. By this simulation model, we have estimated the order of magnitude of the effects of various design parameters affecting the undamped vibration.