ADDITIONAL 4-WHEEL STEERING WITH FEEDBACK CONTROL
A computer controlled additional steering of all 4 wheels of a passenger car can be used to correct disturbances much faster than the human driver could do. Based on a complex 4-wheel model and a corresponding tyre model the behaviour of the vehicle in critical situations, especially cornering at μ-split conditions are simulated. Different control schemes, based on the linear 2-wheel model, are compared and their effects evaluated with respect to path deviation and the change of the heading angle. The results show that the in-troduced feedback control using a reduced observer and a special strategy to identify the μ-split conditions leads to the best corrections. The quality of the control is tested with the cornering on a surface with randomly changing friction.