Automotive steering control in a split-μ manoeuvre using an observer-based sliding mode controller

In this paper a sliding mode integral action controller and sliding mode observer are used to enhance vehicle stability in split-mu-manoeuvre. Anti-lock braking systems (ABS) have become an integral part of modern cars, and they have dramatically improved vehicle handling in braking manoeuvres. However, when a vehicle attempts to brake on a surface with uneven friction coefficient such as on wet or icy roads, a so-called split-mu scenario, the yaw moment generated by the asymmetric braking can prove demanding for an inexperienced driver. The controller presented here works in conjunction with a conventional ABS system to provide safe and effective braking through steer-by-wire. This paper extends previous state-feedback work by only using certain measurable quantities in the controller, estimating further signals by employing an observer.