Analysis for vehicle dynamics and steering system parameters effect on steering characteristics of steering feel (Fundamental study for performance design of objective target on steering feel)

Abstract

The purpose of this paper is to clarify the effect of vehicle dynamics and steering system parameter on steering feel. The objective evaluation method for on-center and off-center evaluates steering effort, steering torque gradient, torque hysteresis and other values. Steering effort characteristics such as steering torque-steering angle, steering torque-yaw velocity or steering angle-yaw velocity are important properties for steering feel. Therefore the performance design of steering feel should be based on the steering characteristics. For example, some studies focus on the stability factor for steering feel by changing tire performance. However changing stability factor also changes yaw gain (yaw velocity/steering angle) and self-alignment torque (SAT) characteristics. The steering effort and the steering damping are under influenced of vehicle dynamics. The steering system parameters i.e. stiffness of linkages, frictions and setting of power steering (PS), such as assistance curve, damping control and others, also has influences the steering characteristics. Since many parameters are necessary in the detailed model, it is difficult to clarify the effect of each parameter on the steering characteristics. This paper examines the influence of steering system parameters and vehicle dynamics on the steering characteristics analytically and formulates. The model of the investigation consists of bicycles vehicle model and steering system with three frictions, three damping element, steering linkage, PS assistance curve and damping control. These steering system stiffness components and PS assistance torque decrease the effect of the friction or the damping on torque hysteresis. This study assists to understand the effect of the steering system and vehicle dynamics on the steering effort characteristics.