Delphi's Active Front Steering System Delivers Leading-Edge Vehicle Stability and Variable Ratio Control

PARIS -- Delphi Corporation featured its new Active Front Steering (AFS) system during a media event held in Mortenfontaine, France, this week. Delphi's Active Front Steering (AFS) system will enable vehicle manufacturers to improve vehicle stability control and to program the desired variable steering ratio while virtually eliminating tradeoffs to base steering performance such as noise, lash, returnability, and on-center feel. In addition, the Delphi system is designed for efficient interaction with conventional hydraulic steering. Delphi's AFS system can be installed with no increase in hydraulic system or component size, resulting in efficiencies comparable to traditional hydraulic steering. "Delphi has demonstrated its active front steering system capabilities and received very positive remarks from several vehicle manufacturers," said Jean Botti, chief technologist, Innovation Center, Delphi Dynamics & Propulsion Center. "Our design addresses many of the vehicle manufacturers' concerns and as a result provides a transparent, smooth system with virtually no compromise or tradeoffs to base steering performance." Delphi AFS helps provides drivers with simplified city driving and parking by reducing the turning required at low speeds so that a hand-over-hand parking maneuver can be accomplished in as little as two thirds of a turn of the steering wheel. Delphi AFS smoothly transitions from a low-speed steering ratio to a high-speed steering ratio, providing a tighter, sportier feel for driving enjoyment and better control on the highway. AFS accomplishes this by modifying the steering kinematics, or motion, of the vehicle in a manner similar to steer-by-wire. The system electronically influences the steering angle on the wheels enabling it to be greater or less than the driver's steering wheel angle input. Hence, turning into a parking spot or even maneuvering a hairpin turn at moderate speeds can be accomplished with significantly fewer turns of the steering wheel. In essence, the system electronically turns the road wheels at a rate different than the rate the driver turns the steering wheel. Although some may think this could be intrusive or controlling, those that have experienced Delphi AFS realize it helps make driving very easy and enjoyable with a very natural, transparent feel. Unlike steer-by-wire, AFS maintains the mechanical link and uses the existing electrical architecture. This mechanical link helps insure system safety. I f the system is switched off or inadvertently loses power, Delphi AFS engineers incorporated a smooth default to the base steering ratio without disturbing or alarming the driver. AFS is the newest technology in Delphi's line of Advanced Vehicle Dynamics, which utilizes integrable control technology to help enhance safety and improve vehicle performance, ride and control. AFS can be integrated to provide a seamless connection between steering, braking and suspension subsystems. Delphi Active Front Steering can be integrated with controlled braking to provide a more effective vehicle system solution to stability control than brakes alone. AFS instantaneously delivers steering control; counter steering the vehicle to bring it back on its intended course and blending in braking, if needed. This is accomplished through finely tuned electronic controls that are virtually transparent to the driver. In addition, this integration can help minimize vehicle-stopping distances on split and mixed coefficient surfaces while maintaining directional stability.