Customer Magazine Article

Feature article written for Delphi Chassis System's quarterly
customer magazine "Thinking Ahead" by Richard Stewart
 
Delphi's TRAXXAR System
To Enhance Vehicle Stability — Affordably

The roadway is slippery-wet. You're driving near the limits
of control, pushing the car, to test a new stability enhancement
system from Delphi Automotive Systems. You enter a curve fast,
both hands gripping the wheel, poised to make correction if the
back-end slips. You feel it start to go, but in an instant the car
recovers. You have full control and can steer safely through the
curve.
    The car is a Geo Storm, a demo unit equipped with Delphi's
TRAXXAR Vehicle Stability Enhancement System. It integrates
the major chassis control systems for optimum vehicle balance
and greatly enhanced control and stability. Without it, the car
would have spun out, as you expected. With TRAXXAR, it
maintained your intended path, improving your ability to control
its direction at the outer edge, extending the vehicle's active safety
envelope.

No Surprises in Handling
"TRAXXAR makes the vehicle much more predictable near the
limit and at the limit — no surprises," says Don Schenk, staff
development engineer with Delphi Chassis Advanced Product
Development. "With this technology, vehicle control is evolving
into an extension of the driver's senses. It can help keep the driver
from getting into trouble on any kind of road surface, in all
weather conditions."
    The system integrates the steering, braking, suspension and
engine controls into a quick-response system that can intervene
at the first sign of instability. It's designed around sensors that
monitor what the vehicle is doing vs. what the driver is asking it
to do, Schenk observes. Building on the ABS and traction control
systems already in place on a vehicle, TRAXXAR adds more
sensors and ties them all together with high-speed communication
links.
    To develop TRAXXAR, Delphi Automotive formed a chassis
integration team that included Delphi Chassis, Delphi Energy &
Management, Delphi Packard Electric and Delphi Saginaw
Steering Systems. Rounding out the team was Delco Electronics.
    "That kind of expertise under a single umbrella makes us a
very strong competitive force with our TRAXXAR system," notes
Rick Foster, manager of Delphi Chassis Algorithm & Electrical
Systems. He feels that Delphi Chassis is uniquely positioned to
integrate the other systems in the chassis environment. "We have
expertise both in brakes and suspension — two vital components
in stability enhancement. I can't think of any competitor who has
the experience we have those areas."

Sensing When Problems Exist
TRAXXAR is fundamentally a stability management system
that uses the brake system as its main input and control output.
Individual wheel-speed sensors monitor how fast each tire is
turning. Sideways motion is detected by a lateral accelerometer.
Another sensor monitors the angle of the steering wheel, to help
determine the driver's intended path. At the heart of the sensing
system is an advanced yaw rate sensor that monitors the turning
moment of the vehicle around its vertical axis. A complex
algorithm determines when the vehicle is operating outside its
safety limits and how the system controller should react to bring
it back in — by selectively applying brakes at any of the four
corners, reducing or increasing engine torque, and controlling the
Real-Time Damping system.
    "Our TRAXXAR technology is a great step forward," says
Development Engineer Schenk. "We're making the handling and
braking work in concert to produce a desired outcome, rather than
having each system operate independently and the driver make
the tradeoffs. The system is designed to keep the vehicle from
veering off the driver's intended path, even if it exceeds the limits
of the laws of physics," he notes. "Even then, the system is
designed not to surprise the driver by any sudden change in its
characteristics."

Not Just for Luxury Cars
Bill Schaid, manager of the Delphi Chassis TRAXXAR Global
Planning Team, sees the system as a natural extension of ABS
and traction control. "It's the next level of vehicle stability
enhancement, and we plan to bring it to all segments. Our goal is
to take the technology out of the realm of the leading-edge, niche
markets to the cars and trucks more people can afford to buy,"
he says. "That differs from the strategy of our competitors, who
are designing their systems for the luxury market alone." Variations
of TRAXXAR are being tested on platforms that range in size
from very small, a Geo Storm, to a very large, a Cadillac STS.
    Schaid reports that the TRAXXAR system being offered for
Cadillac integrates an advanced suspension system, an advanced
steering system, and advanced electronics that enable it to perform
with the best of the competition. "But the Cadillac system is not
intended to be our crowning glory, because we really believe that
the small cars and light trucks are the ones that can best take
advantage of the system. We'll offer it in various forms of
integration for cars and trucks, and we expect consumers in those
markets to be able to afford it," he explains. "Our intent is to
provide the step up from ABS to the base TRAXXAR system
for a nominal charge."

Flexiblity Adds Value to System
Value-added pricing is possible, Schenk points out, because of the
flexibility designed into the system. With calibration changes alone,
TRAXXAR can be configured to suit platforms of various sizes
and performance requirements. "The alternative, of course," he
says, "is to have a uniquely engineered system for every possible
platform. But that's not a good idea from a cost standpoint.  The
key is having very sophisticated control capabilities so you can
calibrate to meet a wide range of needs," adds Schenk.
    "Now that we have control authority in the electronics, we can
tailor TRAXXAR to the particular cost/performance needs of the
platform. Just how much performance is required on the vehicle
is up to the manufacturer," he notes. "You can get a lot of
performance and very high value with just the base TRAXXAR
system. The technology is such that it can provide the
cost/performance tradeoffs rather easily."
    Delphi Chassis welcomes the opportunity to work with other
suppliers to produce TRAXXAR systems for automobile
manufacturers, according to Global Planning Team Manager
Schaid. "If a customer wants us to work with a particular supplier
or suppliers to integrate a system for them, we'll gladly take the
lead. With our partner, Delco Electronics, we can work hand in
hand with suppliers to give the customer exactly what he needs.
We at Delco Chassis are in an excellent position to serve as the
primary chassis system integrator," he observes.
    Development Engineer Schenk expects stability enhancement
systems such as TRAXXAR to follow a path similar to that taken
by electronic controls for engines. "In the '60s and '70s, the
industry moved from fully mechanical engine control — with
carburetors and butterfly valves controlling air-fuel mixture — to
full electronic control authority. As a result, now we can calibrate
the engine to suit the operating conditions," he says. "I don't know
why we shouldn't control chassis functions in the same way. I
expect TRAXXAR to be in the forefront of that advance."
 


 
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