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New Volvo Collision Warning with Auto Brake to Help Prevent Rear End Collisions

Volvo Car Corporation continues to address the problem of rear-end collisions by introducing Collision Warning with Auto Brake – a refined warning system that autonomously engages a vehicle?s braking system if the driver fails to act when a rear-end collision with a moving or stationary vehicle is imminent.”This can mean the difference between a serious injury and minor consequences for the occupants of both vehicles,” says Ingrid Skogsmo, Director of the Volvo Cars Safety Centre.The new system will be available in the Volvo S80, V70 and XC70 in the 2008 calendar year.Rear impacts represent a third of all reported collisions and in more than 50 percent of the cases, the driver doesn’t brake at all.Collision Warning with Brake Support was introduced in the 2007 S80 sedan and warned the driver through visual and audible signals of the potential for an impact. This first generation system also prepared and pre-charged the braking system in anticipation of a panic stop. The new Volvo Collision Warning with Auto Brake (CWAB) takes things a step further, automatically activating the braking system to reduce the vehicle?s speed if the driver doesn’t act when a rear-end collision with a moving or stationary vehicle is imminent.[b]Combining radar and camera[/b]While the original warning-only system is radar-based, the new CWAB uses both radar and a camera to detect vehicles in front of the vehicle. The radar monitors an area 150 metres in front of the vehicle while the camera range is 55 metres. Using Data Fusion technology to combine information from the radar and the camera, the system becomes more efficient.”Since the system combines information both from the radar sensor and the camera, it gives such a high confidence level that automatic braking is possible if a collision is imminent,” says Jonas Tisell, technical project manager for Collision Warning with Auto Brake at Volvo Cars. ?The system is programmed to activate autonomous braking only if both sensors agree that the situation is critical.? One of the main advantages of the camera is the possibility of detecting stationary vehicles. As well, with two different monitoring systems at work, it reduces the likelihood of false-alarms. “Statistics show that 50 percent of all rear-end collisions involve a stationary object, which means that Collision Warning with Auto Brake covers twice as many situations as with the present system,” says Tisell.To adapt the warning system to different conditions and to suit individual driving styles, its sensitivity can be regulated in the car settings menu. There are three sensitivity positions.[b]Begins with a warning – and pre-charging of the brakes[/b]If the CWAB-equipped Volvo vehicle approaches another vehicle from behind and the driver does not react, a red warning light flashes in the head-up display on the windscreen. At the same time, an audible signal can be heard. This is designed to help get the driver?s attention to the potential collision and react.”The head-up display gives a clear and very efficient warning”, says Tisell. ?The red light appearing on the windscreen in front of the driver produces the same gut-reaction effect as when you see a brake light in front of you.?If the risk of a collision increases despite the warning, brake support is activated. To shorten the reaction time, the brake pads move against the discs. Braking pressure is also reinforced hydraulically, ensuring effective braking even if the driver does not press the brake pedal particularly hard. [b]Auto Brake lowers impact speed[/b]If the driver doesn’t brake and the sensor system determines that a collision is imminent, the brakes are activated. Auto Brake is designed to lower the impact speed as much as possible to help reduce the risk of injury to the occupants of both vehicles.”A reduction in collision speed from 60 km/h to 50 km/h, for example, gives approximately 30 percent less impact energy,? says Tisell. ?This can mean the difference between a serious injury and minor consequences for the occupants. Depending on the circumstances, it is also possible that the Auto Brake can help avoid the impact entirely.?[b]Adaptive Cruise Control (ACC)[/b]To make driving more comfortable, Volvo Cars has developed Adaptive Cruise Control which is included with the CWAB system. It helps the driver by maintaining the distance to the car in front and the system contributes to relaxed driving control when the traffic flow is uneven. ACC uses a radar sensor to continuously measure the distance to the vehicles in front and the system automatically adapts the speed of the car to ensure that the distance is maintained.The driver activates the cruise control, sets the desired maximum speed above 30 km/h and chooses one of five time intervals to the car in front.When the radar sensor detects a slower vehicle in front of the Volvo vehicle, the speed is automatically adapted to the slower vehicle.”Since Adaptive Cruise Control handles part of the routine driving operations the driver can focus further ahead and drive with greater safety margins,” says Tisell. [b]Distance Alert (DA)[/b]Distance Alert is another new comfort feature that helps the driver keep a proper distance to the vehicle in front even when ACC is not activated. Distance Alert is activated via a button in the centre console. As with ACC, the driver can choose between five settings. If the time gap to the car in front becomes shorter than the selected value, the driver gets visual information in the head-up display on the lower part of the windscreen. If Distance Alert is engaged and ACC is activated, the DA system becomes temporarily disengaged.Both ACC and Distance Alert are tailored to help the driver comfortably follow government regulations around the world that define a minimum distance between vehicles traveling in the same lane.[b]System limitations[/b]Some of the described systems’ availability depends on the number and quality of visible road markings. The lane markings must be clearly visible for the camera. Poor light, fog, snow and extreme weather conditions can make the system unavailable.Source: Volvo Cars of Canada

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