Vehicle Handling and Stability Investigation into Causes of Vehicle Drift during Straight-Line Braking 2006-01-0797

Vehicle drift is a condition where the driver must apply a constant correction torque to the steering wheel in order to maintain a straight-line course of the vehicle during braking. This paper presents an investigation study into the characteristics of a vehicle experiencing steering drift under straight line braking. The aim of the work is to study vehicle stability and the causes of vehicle drift/pull during straight line braking to minimize brake drift level and hence optimize safety measures.

Simulation, modeling and analysis have been performed in a multibody dynamics environment based on actual vehicle data. The simulation study of steering drift during braking and the resulting unstable behavior of a vehicle during straight-line braking which results in lateral drift is presented in this paper. Suspension parameters have been modeled as rigid links joined with flexible bushes so as to observe their effect on a vehicle while braking. Suspension geometry and alignment settings, which define the characteristic response (lateral acceleration, yaw velocity, toe/caster angles) of a vehicle in a transient maneuver, are shown to be primary to a vehicle's directional stability. It is shown that any symmetric inconsistencies can potentially affect a vehicle's performance. The findings from this research have provided an insight into the changes occurring in a vehicle under braking conditions.