TRW Drives Steer-by-Wire

    FRANKFURT, Germany, Sept. 17 At IAA, TRW Chassis Systems,
part of TRW Inc. , will demonstrate how its leading electrically
assisted steering technologies will develop through to steer-by-wire systems
for all classes of vehicles.
    
    "Steer-by-wire means the end of the mechanical connection between the
steering wheel and the road wheels, with electronically-controlled actuators
setting the steering angles and electronically-controlled force feedback to
the driver's steering 'device,'" said Dr. Dieter Fehlings, engineering
director for TRW's European steering operations. "Steer-by-wire will be the
enabler for fully integrated vehicle stability control systems, for collision
avoidance systems, and one day, potentially, even for autonomous driving."

    According to Fehlings, the challenge for this technology is defining the
fault tolerant electrical architecture with internal redundancies that enables
the system, which has no mechanical connection between the steering wheel and
the road wheels. The typical architecture requirements of such a system have
been defined by a European x-by-wire consortium as a result of the 'European
BriteEuRam III' research and development project from 1996 to 1998. TRW now is
working to develop a system, based on the output from this project, that
delivers advanced functionality enabled through a by-wire system, such as
variable steer ratio according to speed and a choice of driver feel, but at a
cost viable for the mass vehicle market.

    Design leap

    Alois Seewald, global director of Research and Development, Steering and
Suspension Systems and Integrated Vehicle Control Systems (IVCS), TRW Chassis
Systems, said, "The leap forward for this technology development will be that
vehicle designers will no longer be constrained by the steering column -- the
field is open for console style steering or side shift steering. Steer-by-
wire also provides benefits in terms of Noise, Vibration, and Harshness (NVH)
and crashworthiness, due to the loss of the steering column, as well as
opening up the tremendous possibilities of vehicle stability control.

    "Coupled with the introduction of brake-by-wire systems, the design of the
chassis will be greatly simplified. Ultimately, there will be four equal
corner modules that will be significantly lighter and easy to fit. Moreover,
steer- and brake-by-wire are key enablers toward the integrated vehicle
control systems that TRW is working toward."

    Technology evolution

    In August, TRW announced major contracts awarded by Fiat and Renault for
its Electrically Assisted Steering (EAS) products. These contracts, for the
Fiat Stilo and Renault Megane vehicles, total over $900 million. The awards
secure TRW's market leading position and bring the company's annual sales for
its EAS products to approximately $500 million.

    "TRW is ideally placed to take this technology forward," explained TRW
Chassis Systems' steer-by-wire specialist, Dr. Heinz-Dieter Heitzer. "The
company is a leader in electrically assisted steering and the force feedback
actuator is an evolution of the column drive steering system and the front
actuator comes from the rack drive system."

    TRW expects that the first vehicles with complete steer-by-wire technology
will go into production near 2010. In the meantime, TRW is leveraging this
development activity along with its Integrated Vehicle Control Systems work
and other 42-volt related developments to prepare cost-effective interim
products that enhance vehicle functionality while leaving the intermediate
shaft in place.