Robust vehicle yaw control using an active differential and IMC techniques

A robust non-parametric approach to improve vehicle yaw rate dynamics by means of a rear active differential is introduced. An additive model set is used to describe the uncertainty arising from the wide range of the vehicle operating situations. The design of the feedback controller is performed using an enhanced internal model control (IMC) technique, able to handle in an effective way both robustness and control variable saturation issues. In order to improve the transient behaviour a feedforward control contribution has been added giving rise to a two degree of freedom structure. Improvements on understeering characteristics, stability in demanding conditions such as μμ-split braking and damping properties in reversal steer and low friction step steer manoeuvres are shown through simulation results performed on an accurate 14 degrees of freedom non-linear model of a segment D car.