Modelling and Validation of the Vehicle Longitudinal Model

Abstract

This paper presents the detailed derivation and validation of a full vehicle model to
study the behaviour of vehicle dynamics in the longitudinal direction. The model
consists of handling and tyre subsystems, an engine model subsystem, an automatic
transmission subsystem and a brake model subsystem. The full vehicle model was then
validated using an instrumented experimental vehicle based on the driver input from
brake and throttle pedals. Vehicle transient handling dynamic tests known as sudden
braking tests were performed for the purpose of validation. Several behaviours of the
vehicle dynamics were observed during braking and throttling manoeuvres, such as
body longitudinal velocity, wheel linear velocity and tyre longitudinal slip, at each
quarter of the vehicle. Comparisons of the experimental results and model responses
with sudden braking and throttling imposed motions were made in this study. It is
concluded that the trends between simulation results and experimental data were found to be almost similar with an acceptable level of error for the application at hand