This
week we continue collision avoidance systems coverage with information on the
Asian and European brands. While information on domestic manufacturer’s systems
was sparse at best, and while the same was true of many of the import brands,
one stood out by offering a wealth of information.
Toyota
Motor Corporation's Pre-Collision System (PCS), the first production
forward-warning collision system, is used on the manufacturer's Lexus and
Toyota brand vehicles. It is a radar-based system that uses forward-facing
millimeter-wave radar. When the system determines that a frontal collision is
unavoidable, it preemptively tightens the seat belts, removing any slack, and
pre-charges the brakes using brake assist to give the driver maximum stopping
power instantly when the driver depresses the brake pedal. Toyota launched PCS
in February 2003 on the redesigned Japanese domestic market Harrier, and in
August 2003 added an automatic partial pre-crash braking system to the Celsior.
In
September 2003, PCS made its first appearance in North America on the Lexus LS
430, becoming the first such system offered in the US. In 2004, Toyota advanced
the system by adding to the radar a single digital camera to improve the
accuracy of collision forecast and warning and control levels. It was first
available on the Crown Majesta (Avalon). In 2006, the debut of the Lexus LS
featured a further advanced version of the PCS; this newer version, dubbed
Advanced Pre-Collision System (APCS), added a twin-lens stereo camera located
on the windshield and more sensitive radar to detect for the first time smaller
"soft" objects such as animals and pedestrians. A near-infrared
projector located in the headlights allows the system to work at night. By
using the LS's Adaptive Variable Suspension (AVS) and electric Variable Gear
Ratio Steering (VGRS), the system can change the suspension damper firmness;
steering gear ratios and torque assist to aid the driver's evasive steering
measures in a system known as "Collision-Avoidance Steering Support".
The Lane Keep Assist system will make automatic steering adjustments to help
ensure that the vehicle maintains its lane in case the driver fails to react.
Also unveiled for the 2007 model
year, the world's first Driver Monitoring System was introduced on the Lexus
LS, using a CCD camera on the steering column. This system monitors the
driver's face to determine where the driver is looking. If the driver's head
turns away from road and a frontal obstacle is detected, the system will alert
the driver using a buzzer, and if necessary, pre-charge the brakes and tighten
the safety belts. A later version of the Driver Monitoring System found in 2008
on the Crown monitors the driver's eyes to detect the driver's level of
wakefulness. This system is designed to work even if the driver is wearing
sunglasses, and at night.
Other advancements to the PCS
appearing on the 2007 Lexus LS include the first rearward-facing millimeter-wave
radar mounted in the rear bumper. This system adjusts the active head
restraints by moving them upward and forward to reduce the risk of whiplash
injuries if an imminent rear collision is detected.
Toyota
began using Night View on the JDM 2002 Toyota Landcruiser Cygnus and on the
2003 Lexus LX 470 available in the US market. In 2008, Toyota added a
pedestrian-detection feature on the Crown, which highlights pedestrians and
presents them on an LCD display located in front of the driver. The latest
Crown also uses a GPS-navigation linked brake assist function. The system,
which is designed to determine if the driver is late in decelerating at an
approaching stop sign, will then sound an alert and can also pre-charge the
brakes to provide optimum braking force if deemed necessary. This system works
in certain Japanese cities and requires Japan specific road markings that are
detected by a camera.
In March 2009, on the redesigned
Crown Majesta,
Toyota again further advanced the PCS, adding front-side millimeter-wave radar
to detect potential side collisions primarily at intersections or when another
vehicle crosses the centerline. The latest version tilts the rear seat upward,
placing the passenger in a more ideal crash position if it detects a front or
rear impact.
Honda’s Collision Mitigation Brake
System (CMBS) was originally introduced as “CMS” in 2003 on the Acura brand in
the U.S. and Canada. It utilizes a radar based system to monitor ahead and
provide automatic braking if the driver does not react to the instrument panel
warning and tightening of the seat belts. Honda had the first production system
to offer automatic braking and also incorporate “E pretensioner” electric
tensioning of the front seatbelts. When activated, CMBS has three stages, first
being audible and visual warnings to brake. In the second stage, the “E
pretensioners” activate to encourage action. In stage three, with collision
imminent, all seat belt slack is taken up and automatic brake activation takes
place to lessen the severity of the crash.
In late 2004, Honda also introduced an Intelligent Night Vision System,
which highlights pedestrians in front of the vehicle by using an audible chime
and an image displayed on the Heads Up Display.
Mazda uses a system that they have named Smart City Brake
Support, which uses lasers to detect vehicles or obstacles ahead of your
vehicle. This system will apply braking and cut engine power in case of
impending collision, and can usually avoid a collision if the speed
differential between vehicles is less than 15 miles per hour.
Nissan and Infiniti offer a laser-based
system on U.S. market cars, which pressurizes the braking system for maximum
brake force. The system also uses adaptive cruise control sensors for some
pre-crash data. In 2008, Subaru
introduced “Eyesight” on home market Legacy’s and Outback’s. This system used
two CCD stereo cameras mounted on each side of the rear view mirror. The system
also has lane departure warning and adaptive cruise control functions. In 2014
all Legacy, Forester and Impreza models worldwide now have the system and it
was further upgraded using cameras which can detect intense color such as brake
lights for input. These systems are only available on automatic and CVT
transmission vehicles.
Audi’s system (Pre-Sense Plus)
works in four phases. In the first phase, the system provides warning of an
impending accident, while the hazard warning lights are activated, the side
windows and sunroof are closed and the front seat belts are tensioned. In the
second phase, the warning is followed by light braking, strong enough to win
the driver's attention. The third phase initiates autonomous partial braking at
a rate of 3 m/s² (9.8 ft/s²). The fourth phase decelerates the car at
5 m/s² (16.4 ft/s²) followed by automatic deceleration at full
braking power, roughly half a second before projected impact.
A second system, called (Pre-Sense Rear), is designed to
reduce the consequences of rear-end collisions. The sunroof and windows are
closed and seat belts are prepared for impact. The optional memory seats are
moved forward to protect the car's occupants. The system uses radar and video
sensors and was introduced in 2010 on the 2011 Audi A8.
Fiat’s “City Brake Control” is
designed as just that, a low speed crash sensing system designed for under 20
miles per hour. The system uses a “Lidar” laser sensor at the top of the
windshield to perform a three step process. First detection activates an ABS
pre-charge, second step enhances hydraulic brake assist sensitivity, and
finally, automatic braking and audible warnings.
Mercedes' “Pre-Safe” system was
unveiled in the fall of 2002 at the Paris Motor Show on the 2003 S-Class. Using
ESP sensors to measure steering angle, vehicle yaw and lateral acceleration and
Brake Assist (BAS) sensors to detect emergency braking, “Pre-Safe” can tighten
the seat belts, adjust seat positions including rear seats (if installed),
raise folded rear headrests (if installed) and close the sunroof if it detects
a possible collision (including rollover). A later version of the Pre-Safe
system was supplemented by an additional function that can close any open
windows if necessary.
Pre-Safe Brake, Mercedes-Benz's
first forward warning collision system, introduced in the fall of 2005 on the
redesigned 2006 W221 S-Class, is cooperating with simultaneously introduced
Brake Assist Plus (BAS Plus) and Distronic Plus systems and provides all the
functions of previous Pre-Safe system while adding a radar-based system that
monitors the traffic situation ahead and provides automatic partial braking
(40%, or up to 0.4g deceleration) if the driver does not react to the BAS Plus
warnings and the system detects a severe danger of an accident. At the 2009
North American International Auto Show, Mercedes unveiled “Attention Assist” on
the 2010 E-class, which, based on 70 parameters, attempts to detect the
driver's level of drowsiness based on the driver's driving style. This system
does not actually monitor the driver's eyes. Also in 2009, Mercedes added the
first fully autonomous braking feature that provides maximum braking force
approximately 0.6 seconds before impact.
In 2013, Mercedes updated Pre-Safe
on the redesigned W222 S-class. Pre-Safe added pedestrian detection, and a
system called Pre-Safe Plus uses a rear radar, which tightens the seat belts,
flashes the rear hazard lights and applies braking to minimize collision
occupant forces. Pre-safe, also with pyrotechnic pretensioners, will tension
the seat belt just prior to the collision.
Volvo’s
“Collision Warning with Automatic Braking” was introduced on the 2007 S80. The
system is operated through a radar/camera fusion and provides a Heads-Up
display warning that looks like brake lights. If the driver does not react, the
system precharges the ABS and increases brake assist sensitivity to maximize
driver braking. Later versions can then perform automatic braking, especially
in impending pedestrian impact situations. Volvo now introduced the first
cyclist detection system in 2013. All Volvo’s systems are laser based.
