Active Front Steering System Research Articles

OBSERVER BASED SENSOR MONITORING IN AN ACTIVE FRONT STEERING SYSTEM SING EXPLICIT SENSOR FAILURE MODELLING

Active front steering is an emerging steering technology for passenger cars that realises a mechatronic superposition of an angle to the hand steering wheel angle that is prescribed by the driver. This contribution describes algorithms, used to ensure – along with others – the overall safety of the system (i.e. preventing hazardous behaviour). In particular, observers are derived for estimating the position of the electric motor, used in the active front steering system as an actuator. These observers are accompanied by common failure patterns such as drift or offset in the sensors. Sample measurements from a prototype vehicle are presented.

Active Four-Wheel Steering System for Zero Sideslip Angle and Lateral Acceleration Control

This paper proposes an active four-wheel steering system. It has three additional points to an active front steering system proposed by authors: 1) active rear steering to realize zero sideslip angle, 2) variable steering ratio to prevent abrupt involution at slowdown, and 3) model following sliding mode controller to become robust against the system uncertainty. Computer simulations demonstrate good maneuverability of the proposed system.

Handling Capabilities of Vehicles in Emergencies Using Coordinated AFS and ARMC Systems

In this paper, an advanced control technique that can be implemented in hard emergency situations of vehicles is introduced. This technique suggests integration between Active Front Steering (AFS) and Active Roll Moment Control (ARMC) systems in order to enhance the vehicle controllability. For this purpose, the AFS system applies a robust sliding mode controller (SMC) that is designed to influence the steering input of the driver by adding a correction steering angle for maintaining the vehicle yaw rate under control all the time. The AFS system is then called active-correction steering control. The ARMC system is designed to differentiate the front and rear axles' vertical suspension forces in order to alter the vehicle yaw rate and to eliminate the vehicle roll motion as well. Moreover, the operation of the SMC is based on tracking the behavior of a nonlinear 2-wheel model of 2-DOF used as a reference model. The 2-wheel model incorporates real tire characteristics, which can be inferred by the use of trained neural networks. The results clearly demonstrate the enhanced characteristics of the proposed control technique. The SMC with the assistance of the ARMC provides less correction of the steering angle and accordingly reduces the possibility of occurrence of the saturation phenomenon that is likely to take place in the operation of the SMC systems.