| 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 trade-offs to base steering performance such as noise, lash,
returnability, and on-centre feel. In addition, the Delphi system is designed
for efficient interaction with conventional hydraulic steering and 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 trade-offs to base steering performance."
Delphi AFS helps provide drivers with simplified city driving and parking
by reducing the turning required at low speeds so that a hand-over-hand
parking manoeuvre 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 realise 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 ensure system safety.
If 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 utilises 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 minimise vehicle-stopping distances on split and
mixed coefficient surfaces while maintaining directional stability.
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