Sensitivity Analysis of Steering System Parameters for a Passenger Car by DOE Method

In this research, important parameters of a rack and pinion steering system in dynamic steady state and transient responses have been investigated. For this purpose, virtual model of a medium passenger car in ADAMS/Car has been used. The model has up to 121 kinematic degree of freedom and includes all components of the rack and pinion steering system. Several different experimental test results have confirmed the validity of the model. Sensitivity analysis have been done based on design of experiments (DOE) method. Two level fractional factorial designs have been selected for this purpose. Steady state cornering and step steer input are the analysis that used for this research. Understeering coefficient, steering wheel torque and steering sensitivity are obtained from the steady state cornering analysis, while the step steer analysis yields yaw velocity overshoot, yaw velocity rise time, lateral acceleration overshoot, lateral acceleration rise time and roll angle overshoot. Each of these characteristics has been selected as a single objective function. The obtained Results indicate that only six parameters from fifteen selected parameters play major roles in objective functions. Thus if the objective function for optimization of this system is a combination of objective functions of this research, optimization can be performed with only six parameters.