A test method for the quantification of on-centre handling with respect to cross-wind

Abstract

During the development process of a new passenger car chassis, certain aspects of the driving dynamics concerning comfort and handling receive particular attention. During this process it is crucial to maintain basic characteristics. One of these basic characteristics is the straight-ahead stability. It is also important that the driver can feel this straight-ahead stability through the steering wheel. With the wording ‘on-centre handling’, both aspects are addressed: the objective straight-ahead stability and the subjective feeling for very small steering wheel movements. This article presents a proposal for the objective description of on-centre handling. A new method is introduced to allow the calculation of characteristic values for the straight-ahead stability without any driver influence. The principle of this new method consists of a comparison between the measured and the calculated yaw velocities. The calculated yaw velocity results from a modified single-track model. The yaw velocity error is the result of the difference between the calculated and measured yaw velocities. After this error is calculated it will be plotted versus the measured disturbance variables (wind, lateral inclination). The vehicle response is more sensitive to the disturbance for a larger gradient of this graph. For the complete description of on-centre handling, it is necessary to characterize the steering feel. Characteristic values are introduced to describe the steering feel and the corresponding vehicle reaction.