Continental contends its Active Passive Integration Approach (APIA), which links existing active safety devices such as antilock brakes and electronic stability control (ESC) with passive safety systems such as seatbelts and airbags, can prevent crashes before they occur.
“We are in the middle of a revolution of smart vehicles,” Continental’s Dean McConnell, director-product strategy, electronic brake and safety systems, tells attendees of an active safety session at the recent Convergence automotive electronics conference in Detroit.
This revolution, McConnell says, is driven by highly capable microcontrollers designed not to take control away from drivers but to actively support them with processing speeds that vastly exceed that of the human brain. “It adds functionality, without adding much cost,” McConnell says.
VW Golf back end swings upward to avoid being struck by aggressive tailgater in an APIA-equipped BMW 3-Series.
APIA enables up to 22 safety devices on a car to rapidly exchange data about the activities of the driver, the behavior of the vehicle and the status of the driving environment. A “closing velocity” sensor detects nearby events or objects that could cause an accident, such as a vehicle ahead suddenly braking.
A “danger control module” computes a hazard potential and, if an accident appears imminent, initiates a staged response to minimize its severity. The driver gets a visual or “haptic” warning (accelerator pedal vibration), seatbelts are pulled taut, windows and sunroof close automatically, the brake system is pre-pressurized and front seats are brought to the ideal position for airbag deployment.
McConnell concedes the two potential OE customers are unlikely to source the entire APIA package from Continental, saying some manufacturers want to maintain in-house control over certain dynamic safety functions.
“No one wants the whole APIA system at this time,” McConnell tells Ward’s.
The first step toward integrating APIA – likely in the 2008 timeframe – is to coordinate the environmental sensing with engine torque management and with braking functions.
At a demonstration last week of APIA – installed on a BMW 3-Series sedan – at the Pontiac Silverdome here north of Detroit, Continental officials say the technology would cost an auto maker an extra $200 to $300 for a vehicle already equipped with ESC and adaptive cruise control (ACC).
Continental estimates the cost to an auto maker to add ACC as well is approximately another $300. Continental supplies ACC, as do competitors TRW Automotive, Robert Bosch GmbH, Denso Corp. and Delphi Corp.
ESC and ACC are critical components of APIA.
ESC uses a yaw sensor to detect when a vehicle is skidding out of control and a steering-angle sensor to determine the driver’s intended direction. ESC allows rapid braking of individual wheels to help the driver regain control.
A growing body of research confirms ESC is successful in preventing accidents and could prevent 20% of fatalities if installed on a large scale, the supplier says.
About 50% of new cars in Europe have ESC, compared with 10% in the U.S. The U.S. installation rate is expected to reach 20% next year, suppliers say.
Continental is a leading producer of ESC and reports installation rates for the system as high as 90% on Chrysler Group’s new rear-wheel-drive 300 Series sedan.
ACC, however, has a much lower penetration rate. It uses radar to detect moving vehicles in the lane ahead and works in tandem with the throttle and brakes to maintain a comfortable distance from the car ahead. If the lead vehicle brakes suddenly, so does the ACC vehicle.
Significantly more expensive than conventional cruise control, ACC appears on luxury cars, including five Mercedes-Benz models, the Cadillac XLR and Volkswagen Phaeton. Five BMW models offer the feature as a $2,200 option. The Toyota Sienna minivan also offers ACC. (See related story: Adaptive Cruise: It’s All About Trust)
ACC has been marketed as a convenience feature, but its inclusion in APIA suggests the technology has a future as an accident-prevention device as well. Most ACC systems will brake a vehicle down to a certain speed – usually about 25 mph (40 km/h) – at which time the driver must take over and complete the braking event.
With APIA, when the ACC’s radar beam detects a vehicle slowing close ahead, pressure in the brake system is boosted so that clearance between the brake pads and discs is reduced to zero.
The closer the car gets to the lead vehicle, the harder the APIA vehicle decelerates, at a rate of up to 0.3 g (the maximum allowed by law for automatic braking).
Additional stopping power comes when the vehicle’s Brake Assist system identifies an emergency deceleration event and applies maximum stopping pressure once the driver hits the brake pedal. Brake Assist allows a car to stop one second faster than a car without it, which translates into reduced stopping distance. (See related story: Conti’s APIA Solution Intrusive But Reassuring)
During the recent Silverdome test drive, the technology was impressive, consistently performing the tasks expected. The lead vehicle actually was the back end of a Volkswagen Golf, suspended from two spring-loaded arms attached to the top of a Mercedes-Benz SUV.
The Mercedes set the pace, and the APIA 3-Series was driven up close behind the Golf back end, to simulate tailgating.
Once close enough to the Golf, the APIA car applied the brakes, even without braking input from the driver. Haptic feedback in the form of pedal vibration was obvious, much like the sensation when ABS is activated.
When the Golf stopped suddenly, the APIA car did as well, triggering a rapid succession of events to improve cabin safety.
In a matter of seconds, the windows and sunroof closed (to prevent severe injuries in the event of a rollover), the ABS was activated and the seatbelts pulled the passenger back tightly against the seat.
Still, APIA has its limits. Many test drivers struck the spring-loaded Golf’s back end, which pivoted skyward and allowed the APIA 3-Series to pass underneath.
The demonstration was not designed to prove that aggressive drivers can tailgate safely. “We cannot overcome the laws of physics,” says Jurgen Diebold, manager of advanced driver assistance at Continental.
In its research, Continental estimates APIA can reduce stopping distances up to 42 ft. (13 m) at 60 mph (96 kph) depending on tire conditions and can dissipate up to 34% of crash energy, Diebold says.
The APIA concept is an extension of Continental’s 2000 initiative to shorten a vehicle’s stopping distance to 98 ft. (30 m) through an integration of braking, steering and suspension technologies. (See related story: Continental Shows Off 30-Meter Car)
However, one piece of that earlier concept left behind in APIA is Continental’s sidewall torsion sensor.
Magnetic particles were embedded in a tire’s sidewall, and a sensor in the wheel well gathered critical information about the driver’s intended direction, based on lateral forces applied to the tire. That technology proved expensive and somewhat redundant.