Volvo safety system for avoiding collisions at low speeds
By Mike Hanlon
December 6, 2006
December 7, 2006 Volvo has announced more innovative safety technology – a unique ‘City Safety’ system that could help drivers avoid 50 per cent of all rear-end, low speed accidents that often happen in urban environments or slow moving traffic. Statistics reveal that 75 per cent of all reported collisions occur at low speeds of up to 30 km/h (18.7 mph). The Volvo system, called ‘City Safety’, is active up to 30 km/h and keeps a watchful eye on traffic up to six metres in front of the car with the help of an optical radar system integrated into the upper part of the windscreen. If a car in front suddenly brakes or is stationary, the system will automatically pre-charge the brakes to help the driver avoid an accident by slowing down in time, or steering away from a potential collision. However, if a collision is imminent, the system will activate the car’s brakes automatically.
“The system offers benefits to all involved. For the occupants of the car in front, the risk of whiplash injuries is avoided or reduced, plus it can help reduce or even eliminate the cost of repairs to both vehicles,” says Ingrid Skogsmo, director of the Volvo Cars Safety Centre.
The system runs a calculation 50 times per second to determine what braking speed is needed to avoid a collision based on the distance to the object in front and the car’s own speed. If the calculated braking force exceeds a given level without the driver responding, the danger of a collision is considered imminent and ‘City Safety’ helps avoid or reduce the consequences of a collision by automatically activating the car’s brakes and reducing the throttle.
The ‘City Safety’ system works equally well day or night, but will have the same limitations as any other radar systems, so can be limited by fog, mist, snow or heavy rain. If the sensor on the windscreen is obscured by dirt or snow the driver is alerted via the car’s information display.
“It is important to emphasise that the system does not absolve the driver from driving with adequate safety margins in order to avoid collisions. The automatic braking function is only activated when the system assesses that a collision is imminent. The system then steps in to limit the consequences of the imminent collision or, in some cases, totally avoid it,” explains Ingrid Skogsmo.
The ‘City Safety’ system should be available within two years. However, Volvo recently introduced Collision Warning and Brake Support active safety systems with the all-new Volvo S80, which also help to avoid and reduce damage and injuries from collisions. These systems alert the driver via audible and visual signals if the gap to the car in front is reducing so quickly that an impact is likely. It automatically pre-charges the braking system so that braking is as effective as possible in an emergency situation but doesn't offer full auto-braking.