Concept and Functionality of the Active Front Steering System

Active Front Steering (AFS) provides an electronically controlled superposition of an angle to the steering wheel angle. This additional degree of freedom enables a continuous and driving-situation dependent adaptation of the steering characteristics. Features like steering comfort, effort and steering dynamics are optimized and stabilizing steering interventions can be performed. After the successful introduction of AFS (or active steering) together with the new BMW 5-series into the international market, ZF Lenksysteme focuses on aspects like system modularization and integration. For that reason the system bounds, its functionality, and the required system interface are defined to provide a compatibility to several overall chassis control concepts. This paper focuses on a modular system concept and its respective advantages and requirements.