Delphi Introduces Innovative Four-Wheel-Steering System at SAE 2000
1 March 2000
Delphi Introduces Innovative Four-Wheel-Steering System at SAE 2000
QUADRASTEER(TM) by Delphi Allows Full-Size Vehicles
To Maneuver Like Compact Cars
TROY, Mich., March 1 -- Delphi Automotive Systems
formally introduces its QUADRASTEER(TM) four-wheel steering system at the
Society of Automotive Engineers (SAE) 2000 World Congress at Cobo Center in
Detroit this week (exhibit #1829).
QUADRASTEER is an electronic four-wheel steering system that enables
full-size vehicles greater ease of maneuverability while driving or trailering
at low speeds, and improved stability, handling and control at higher speeds
-- especially while trailering.
Delphi's unique system electronically controls the direction of the rear
wheels, helping shorten the turning circle on full-size vehicles. The smaller
radius allows full-size vehicles to maneuver as adeptly as compact cars.
Based on tests with full-size sport utility vehicles (SUVs) and pickup
trucks, QUADRASTEER reduces the minimum turning circle diameter by an average
of 20 percent. In fact, one full-size pickup's turning circle diameter was
reduced from 46.2 feet (14.08 meters) to 37.4 feet (11.40 meters), making it
comparable to a Nissan Altima at 37.4 feet (11.40 meters) and a Saturn Coupe
at 37.1 feet (11.31 meters).
"The effect that QUADRASTEER has on maneuvering a full-size vehicle is
remarkable," said Paul J. Tosch, Delphi vice president and president of
Delphi's Saginaw Steering Systems division. "We believe there is going to be
a lot of excitement around this technology when it hits the market, and we are
confident it will help our customers differentiate their products."
Earlier this year, QUADRASTEER was featured on General Motors Corp.'s GMC
Terradyne concept truck displayed at the North American International Auto
Show. QUADRASTEER will be available in the market early this decade on a
customer vehicle program to be announced.
It combines conventional front-wheel steering with an electrically powered
rear-wheel steering system. The system has four main components -- a front-
wheel position sensor, steerable solid hypoid rear axle, electric motor-driven
actuator, and a control unit. Hand-wheel position sensors and vehicle speed
sensors continuously report data to the control unit, which determines the
appropriate angle of the rear wheels. Algorithms are then used to determine
the correct phase of operation.
The system operates in three principal phases: negative, neutral and
positive. At lower speeds, the rear wheels turn in the opposite direction of
the front wheels. This is the negative phase. At moderate speeds, the rear
wheels remain straight or neutral. At higher speeds, the rear wheels are in
the positive phase, turning in the same direction as the front wheels.
QUADRASTEER will give added control to drivers of full-size vehicles who
trailer. During low-speed, negative-phase towing maneuvers, the trailer
follows the true vehicle path much more closely than with two-wheel steering.
This makes driving in city traffic with a trailer easier. Low-speed
maneuvering such as backing into a boat launch or parking a camper is also
easier with QUADRASTEER. When backing a trailer, the negative phase greatly
improves the trailer response to steering inputs, making it easier to place
the trailer into position.
At higher speeds, trailering stability is significantly enhanced. The
positive rear steering phase reduces the articulation angle between the
vehicle and trailer, which reduces the lateral forces applied to the rear of
the vehicle by the trailer. This, in turn, reduces the yaw velocity gain and
increases yaw damping of the vehicle and the trailer system. The net result
is increased trailering stability, reduced trailer sway and reduced driver
corrective steering to external disturbances such as wind gusts, semi-truck
passing and irregular road surfaces.
Larry Tomczak, director of engineering at Delphi's Saginaw Steering
Systems division, adds: "QUADRASTEER also enhances stability at higher speeds
when there is no trailer. Steering the rear wheels in the same direction as
the front wheels at higher speeds helps reduce the vehicle yaw, or rotational
motion, required to accomplish a maneuver, thus helping to stabilize the
vehicle response during passing, lane change or evasive maneuvers even under
adverse road conditions."
Completely compatible with, and enhancing to, four-wheel-drive systems,
QUADRASTEER can be driver-selective or fully automatic -- depending on the
automaker's requirements. For example, using a selection panel, the driver
could adjust the performance of the rear-wheel steering for different driving
conditions. Selections might include one for general driving, one for
trailering and one for two-wheel steering. The QUADRASTEER system also
provides a controlled return to regular two-wheel steering if the four-wheel
steering system is damaged.
Delphi Automotive Systems, headquartered in Troy, Mich., USA, is a world
leader in transportation and mobile electronics components and systems
technology. Delphi's three business sectors -- Dynamics & Propulsion; Safety,
Thermal & Electrical Architecture; and Electronics & Mobile Communication --
provide comprehensive product solutions to complex customer needs. Delphi has
approximately 213,500 employees and operates 175 wholly owned manufacturing
sites, 41 joint ventures, 53 customer centers and sales offices and 27
technical centers in 38 countries. Regional headquarters are located in
Paris, Tokyo and Sao Paulo, Brazil. Delphi can be found on the Internet at
http://www.delphiauto.com .