Enhancement of Vehicle Handling Based on Rear Suspension Geometry Using Taguchi Method

Studies have shown that the number of road accidents caused by rollover both in Europe and in Turkey is increasing [1]. Therefore, rollover related accidents became the new target of the studies in the field of vehicle dynamics research aiming for both active and passive safety systems.This paper presents a method for optimizing the rear suspension geometry using design of experiment and multibody simulation in order to reduce the risk of rollover. One of the major differences of this study from previous work is that it includes statistical Taguchi method in order to increase the safety margin. Other difference of this study from literature is that it includes all design tools such as model validation, optimization and full vehicle handling and ride comfort tests.Rollover angle of the vehicle was selected as the cost function in the optimization algorithm that also contains roll stiffness and height of the roll center. In order to form the cost function, five different geometrical factors have been selected as design variables. The ultimate aim is to minimize the cost function by increasing the roll center height and suspension roll stiffness. To run the optimization routine, a rigid rear suspension mechanism used on the 7 m bus has been modeled using Adams/Car software program. Opposite wheel travel analysis has been performed as an optimization test method in order to simulate the vehicle passing over the bump. Then, in order to reach the minimum value of the cost function, statistical Taguchi method was used to perform design of experiments (DOE).In total, 27 experiments have been performed according to the selected design variables. Therefore, in each different experiment, the roll center height and the roll stiffness were measured. Then, the cost function was calculated and recorded to compare with the future iterations. The attachment points giving minimum cost function value are expected to be the optimal coordinates for installing the suspension mechanism