Coupled 6DoF Motion and Aerodynamic Crosswind Simulation Incorporating Driver Model 2017-01-1525

Because of rising demands to improve aerodynamic performance owing to its impact on vehicle dynamics, efforts were previously made to reduce aerodynamic lift and yawing moment based on steady-state measurements of aerodynamic forces. In recent years, increased research on dynamic aerodynamics has partially explained the impact of aerodynamic forces on vehicle dynamics. However, it is difficult to measure aerodynamic forces while a vehicle is in motion, and also analyzing the effect on vehicle dynamics requires measurement of vehicle behavior, amount of steering and other quantities noiselessly, as well as an explanation of the mutual influence with aerodynamic forces. Consequently, the related phenomena occurring in the real world are still not fully understood. Reproducing vehicle motion in the real world requires the ability to recreate disturbances from the driving environment, including natural wind and road surface undulations, and to predict the dynamic aerodynamics resulting from the driver’s operations such as steering, braking and other actions. This study, therefore, focused on a crosswind situation which involves relatively large changes in vehicle behavior induced by air pressure inputs to the vehicle. A two-way coupled numerical simulation method was developed for performing aerodynamic calculations using a vehicle motion model with six degrees of freedom and incorporating a driver model for keeping the vehicle in its driving lane.

The results obtained with this calculation system revealed that aerodynamic parts reduced the amount of corrective steering needed, which coincided with the experimental data. It led to the visualization of the aerodynamic phenomena assumed to be the causal factors.