Mathematical modeling for vehicle dynamics, steady state cornering performance prediction using non linear tire data employing a four wheel model

An accurate full vehicle mathematical model is required to represent the vehicle behaviour in order to design its control system. The model must lead to control of crucial parameters such as yaw control, anti-roll control etc. Such a model also aids in performance prediction of the vehicle prior to building the actual prototype. This paper describes the development of a four wheel vehicle model to study the behaviour of a vehicle during steady state cornering manoeuvres. The vehicle model is designed taking into account the nonlinear tire characteristics and suspension geometry effects. A fifth order polynomial, on the basis of tire data, is constructed for the tire model. The vehicle model is then used to predict vehicle understeer / oversteer. Steering response for different vehicle configurations are computed using numerical solutions. Graphs representing understeer gradient are plotted to give a better insight to the vehicle behaviour.