Detroit-In a move that could signal the beginning of a new era in automotive component design, Delphi Automotive Systems (Saginaw, MI) has unveiled a new four-wheel steering system that employs no direct mechanical linkages to the rear wheels.
When traveling at low speeds, Quadrasteer can turn the rear wheels in a direction opposite of the front wheels. Result: a 20% tighter turning radius.
Known as Quadrasteer, the system changes the nature of steering in two significant ways: It allows all four wheels to turn at once; and it uses a steer-by-wire concept on the rear wheels. The system is being incorporated into an SUV or truck slated for the 2003 model year.
Introduced at the Society of Automotive Engineers 2000 World Congress in March, Quadrasteer enables a vehicle's rear wheels to turn independently. By using wheel-speed and position sensors to determine a vehicle's speed and turning angle, the system can "decide" whether the rear wheels should turn in the same or the opposite direction as the front wheels.
Automotive experts say Quadra-steer's tight turning ability makes it ideal for large vehicles. "One of the great deterrents to driving SUVs is the long wheelbase and the clumsiness in tight situations," notes David Cole, director of the Office for the Study of Automotive Transportation at the University of Michigan. "This helps solve that problem."
For design engineers, however, Quadrasteer's real impact may be its use of steer-by-wire technology. The steering wheel is connected by wires to an electric motor that actuates the rack-and-pinion.
Industry observers say that Quadrasteer's use of steer-by-wire is also significant because it could pave the way for more widespread use of other existing drive-by-wire technologies, such as brake-by-wire or two-wheel steer-by-wire.