Abstract
Keywords:
Steering Ratio, Steering Wheel Angle, Road Wheel Angle, Vehicle Control
Abstract
This paper investigates the relationship between the driver’s hand wheel input (steering wheel angle) and the resulting front road wheel steer angle. This relationship was studied as a function of road speed during on-centre driving and has been defined as the ‘dynamic steering ratio’. It was observed that the dynamic steering ratio varies as a function of road speed; the observed dynamic steering ratio was twice the kinematic steering ratio at a road speed of 100km/h. The dynamic steering ratio has been modelled as a function of kinematics, compliance and turn curvature. Whilst kinematics and compliance effects are relatively independent of road speed, turn curvature, to achieve the low levels of lateral acceleration associated with on-centre driving, is dependent on road speed. The compliance contribution was divided into the compliance of the steering system and from the suspension. Effects of tuning the compliance in conjunction with the steering ratio characteristic on the driver / vehicle controllability was investigated taking into consideration the dynamic steering ratio.