Development of Random Road Surface Input Simulation Method

This paper deals with a random simulation method of vertical vehicle motion with 8 degrees of freedom model. Random road surface input is needed to analyze the vertical motion of actual running vehicle. Road surface input based on the ISO standard is used. In this standard, the road surface profiles are determined by space frequency. Therefore, it is needed to convert space frequency to time frequency for random road surface input simulation. The characteristics of the suspension are analyzed using this random simulation method, and the effect of nonlinear suspension friction characteristics on vehicle ride comfort is derived and the validity of this method is indicated.