London, May 28 : A car that protects its occupants from a crash moments before a side-on collision has been crash-tested by European engineers.
The system has stereo cameras and radar sensors that continually scan the environment and a central computer that analyses the data. The cameras are integrated in the doors of the car and the radar sensors are placed in the car wings.
By the time the crash is only a second away, the cameras have long identified the car that will cause the accident. Then, radar measure how far the car is away. With about 200 milliseconds left for the crash, the side-impact protection system gets activated. The impulse from the central computer releases a surge of electricity that heats a wire made of a shape memory alloy.
The heat bends the wire, which then releases a spring. The spring slackens and pushes a steel bolt, which is integrated in the seat, towards the door. At the same time a stable metal body in the door is brought into position to support the steel bolt.
The bolt and the metal box stabilize the car door and absorb energy on collision, thereby dramatically reducing the risk of injury.
The system is the latest demonstration of car safety devices that take action before a crash, not just afterwards.
Evidence from both real and simulated crashes shows that drivers rarely manage to react to a typical 30 to 40 kilometers per hour side impact, and there is very little distance between passengers and the object that strikes the car.
"The energy of the impact is transferred to the 'unstruck' side of the vehicle," New Scientist quoted Joachim Tandler, an engineer at carmaker Continental, which is leading EU-funded project APROSYS, as saying.
"Normally that connection could not be complete," Tandler added.
The car was subjected to a safety test used by European car safety watchdog NCAP, which involves hitting it with a barrier traveling at 50 km/h. The tests took place at the he brace-for-impact system reduced the amount that the barrier penetrated the car by between 5 and 8 centimeters - enough to make a difference to the safety of the passengers in the car.
"The intrusion velocity was considerably reduced," Tandler said.
Although the brace was a success, the sensors and software used to predict a collision are the parts most likely to be adopted first by car manufacturers.
"We can give conventional in-crash devices like airbags more time to react," he added.