CITROňN "C5 BY WIRE" DEMONSTRATION
CitroŽn is presenting a new technology demonstration
vehicle, "C5 by
Wire". This vehicle reflects two of the objectives pursued by the
Marque: to develop a vision of the automotive future and to
continuously devise new solutions to improve driving pleasure, safety
and interior layout. Originally developed by the aerospace
industry, “X-by-Wire” technology involves replacing the mechanical
connections between controls (steering wheel, pedal assembly, etc.) and
sub-systems (steering, brakes, etc.) with electronic connections.
This concept is illustrated by the cabin layout of the CitroŽn "C5 by
Wire". First, the steering wheel groups the steering, braking and
acceleration controls, and second, there is no pedal assembly. The
multifunctional steering wheel thus plays an essential role.
Already presented on the C-Crosser and C-Airdream
concept cars, “X-by-Wire” technology is now being partly trialled on
the CitroŽn C5. This production vehicle has a V6 3.0i engine developing
210 bhp DIN (152 kW), mated with an automatic gearbox.
technology opens new possibilities in interior design by replacing
mechanical components such as the pedal assembly and the steering
column. Grouping all the driving controls on the wheel is an ergonomic
solution that also promotes easy use. As a result, controls can be
activated more quickly for enhanced safety.
Operating principle of the driver interface
driving functions are managed by the driver, who holds the steering
wheel in the "quarter-to-three" position in order to activate the
The lower and upper parts of the steering wheel hoop
have been removed,
allowing full use of the all-electric variable-ratio steering, which is
particularly sharp at low speeds.
The driver uses the right or left
thumb to reach the forward-facing acceleration paddles on either side
of the wheel. It was necessary to provide two paddles in order to allow
the driver to accelerate and, at the same time, to activate the
lighting on the left, and the windscreen wipers, headlamp washers and
horn on the right.
Automatic cruise control is also available to regulate speed and
enhance driving comfort, avoiding the need for the driver to keep
pressing the paddles. Cruise control is disconnected when the driver
brakes or accelerates.
The brakes are controlled by "triggers” located at either end of the
steering wheel. The driver uses the right or left index finger to reach
these controls. Brake force is applied intuitively.
These controls are all highly ergonomic. They feel completely natural
to use, after just a short time behind the wheel.
The “X-by-Wire” system: technology serving safety
multifunctional steering wheel plays an essential role. Easy to use, it
allows the driver to concentrate on the road, thus clearly contributing
Safety was an essential factor in the development of “X-by-Wire”
systems for the automotive industry.
The absence of the pedal assembly and steering column considerably
enhances safety, since the risk of injury in the event of impact is
In addition, the space freed up for the legs improves ergonomics and
Also, having the controls on the steering wheel increases the speed of
execution, particularly when braking. Precious time is gained, since
the driver no longer has to reach for the brake pedal.
Variable-ratio electric steering
The all-electric steering system provides:
variable steering wheel angle/wheel angle ratio, adjusted automatically
to suit the driver’s requirements and the speed of the vehicle. In
particular, this function makes parking much easier, thanks to the more
direct steering ratio (between one and two turns of the wheel compared
with three turns in general). This feature also ensures pin-sharp
steering at high speeds.
latitude in adapting and defining steering parameters in terms of
torque (controlling wheel vibration, for example), angle (small turns
of the wheels) and vehicle behaviour (overall chassis control).
Electro-hydraulic braking system
braking system is electro-hydraulic. There is no pedal assembly, but
the electric button on the steering wheel plays exactly the same role
as a conventional system. Brake force is applied progressively, in an
intuitive and natural way. To brake, the driver simply applies pressure
to one or both of the steering wheel handles.
With the "C5 by Wire", CitroŽn is exploring new
options. By eliminating mechanical limits and constraints, it aims to
pioneer more attractive and ergonomic cockpit design that adapts to the
needs of each driver and brings significant progress in active safety.
||© 2001 Julian
Marsh/CitroŽnŽt/SA Automobiles CitroŽn