By-Wire Technology
Creates New Car Concept
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Bertone-SKF FILO by-wire car |
A car concept that uses by-wire
technology to operate steering, accelerator, brake, gear change
and clutch systems was unveiled at the March 2001 Geneva Motor
Show. Developed by SKF, Goteberg, Sweden, and Italian car
manufacturer Bertone, the car, called FILO--Italian for wire--uses
the same technology used in the controls of modern aircraft.
At the heart of each by-wire system is an SKF smart electro-mechanical
actuating unit operated under intelligent control. The Guida-Filo--the
driver's control unit--blends familiar design elements from
today's proven man-machine interface with the benefits of
full by-wire operation. The result is a control arrangement
that eliminates the steering column and pedals, and provides
designers with an unprecedented freedom to pursue new ideas
concerning how we think about cars and driving.
On your mark, get set...
The left and right steering control yokes, which are mechanically
linked, have a full travel of about 20 degrees. The mapping
to the movement of the front wheels is under logic control,
with feedback to the driver being provided as a function of
the loads acting on the steering rack, by an appropriate high-torque
motor. The level of "feel" experienced by the driver
is fully programmable, as is the relationship between movement
of the yokes and movement of the front wheels. The steer actuator
has been designed as the next generation solution, fitting
easily in the front sub-frame assembly of the FILO concept's
original platform.
Stop!
The company reports its Brembo-SKF braking system--even at
this interim stage in solution development--rivals conventional
hydraulic arrangements in performance. Control of the brakes
is duplicated on both the left and right yokes of the driver
control panel, and is activated by squeezing the handgrips.
The mechanical design incorporates a progressive resistance
and a small, but clearly discernible, free-play at the beginning
of the movement, providing the driver with a tactile indication
of when the brakes begin to operate. The system controls each
brake as an individual sub-system under an umbrella control
arrangement for the complete vehicle braking system.
 SKF overview of the FILO by-wire car
Developments in the course of the project have seen repeated
reductions in the weight and overall size of the design. The
complete by-wire caliper assembly is a compact unit, with
a weight comparable with that of the conventional hydraulic
design.
But does it shift?
The operation of gearshift and clutch are so closely coupled
that it's best to consider the systems together. The gearbox
for the platform on which the FILO drive-by-wire car is based
employs a conventional "H-pattern" manual shift
gearbox. To accomplish the second to third and fourth to fifth
movements of the original selector mechanism inside the gearbox,
precise linear and rotational movement is required.
As with much of the actuator development within the FILO
concept, a deliberate decision was taken to modify the original
mechanisms as little as possible. This was done to clearly
demonstrate that these compact designs will fit within the
confined space available in a modern car platform.
 Guida-Filo driver control panel
Shifting is handled via the plus and minus buttons on the
right side of the driver's control unit, neutral being a logical
zero. Reverse is selected via a dedicated button and is protected
from inappropriate selection by logic in the actuator control
unit. Both clutch and gearshift actuating units are on the
conventional 14-volt power system.
The SKF smart electro-mechanical actuating units of the FILO
concept's mechatronics are already performing to levels well
within those required by the vehicle systems they operate.
Production is targeted for 2004.
--KC
For more information: Circle 528 - SKF Industrial Group
or connect directly to their website via the Online Reader
Service Program at http://www.OneRS.net/105df-528
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