Feature Mercedes-Benz's latest research vehicle showcases some rapid-deploying protection systems.
Safety first, safety fast
Just when you thought you had airbags, ESP and ABS figured out, Mercedes-Benz has ramped up its road-safety measures significantly with its ESF 2009 safety research vehicle. Included in its raft of breakthrough safety features, the ESF 2009 doubles a normal car's emergency braking power, fills its doors with expanding metal "airbags", automatically lights up pedestrians and animals at night, pushes passengers towards the middle of the car away from danger and even talks to other cars.
And, in what is sure to be a boon for parents, it even has a roof-mounted camera that can show snapshots of rear-seat behaviour on its multi- media screen and even debuts a new tubular-based child seat. And, Mercedes admits, both child-focused safety devices could be in production in the very-near future. Timed to coincide with the global Advanced Safety of Vehicles Conference in Stuttgart last weekend, Mercedes-Benz gave The National an exclusive sneak preview at its factory in Sindelfingen, Germany, essentially to make the point that current vehicle safety is far from the limits of passenger protection.
It has had thousands of safety engineers working away on technology to help avoid crashes. "The primary aim is to prevent accidents in the first place," says Professor Doctor Rodolfo Schöneburg, Mercedes' director of Passive Safety, Durability and Vehicle Functions. "Where this is not possible, the aim is to mitigate their effects. The 'magic moment' for passive safety innovations is 600 milliseconds before the impact, and we use this time to significantly increase occupant protection.
"But we approach both of these goals without increasing the weight, restricting practicality or compromising the autonomy of the driver. The driver drives and the car provides support." Built in just eight months, the ESF 2009 is based around the new S400 Hybrid limousine. The following is a rundown of the ESF 2009's most intriguing new technologies.
A normal S-Class fitted with Pre-Safe Plus uses three different radar systems to detect crashes and, if the computers are convinced you're about to crash, it will automatically slam on the brakes. But the tyres have only so much grip, and even good cars will only decelerate at 10 metres per second squared, or about 1g. This new system sets off an airbag under the engine just before an unavoidable crash. It pushes a grippy, rubber-lined version of the metal sump guard directly onto the road, washing off speed at up to 2.5g. Because the bag pushes the car's nose up off the ground, the timing has to be perfect. "We have to find the right time to inflate the bag, and it's about 100-200m before the crash," says Schöneburg. "At 50kph, that would be roughly 10m before the crash. Too early is counter-productive and too late is obviously too late. "The secret is we use the car's braking," continues Schöneburg. "The car dives down and the idea is to push the car back to the original position. This leads to an additional dynamic force and increases the friction for a short time."
Governments around the world have long mandated side-impact protection beams, but what Mercedes calls Pre-Safe Structure goes even further. When sensors in the side of the car detect an "unavoidable impact", they trigger an airbag inflator inside the beam.
It will almost instantly inflate the steel beam to triple its size, creating more crumple zone, with the pressurised gas itself adding to the strength of the door. Surprisingly, the big problem with the metal bags is not weight, because Mercedes calculates it can actually save half a kilogram per door. The problem at the moment is cost, some of which is legislative. "Right now, it has to fulfil all the static requirements and it has to do that now by staying undeformed, so it's bigger, heavier and more expensive than it needs to be," says Dr Matthias Nohr, Mercedes' manager of Vehicle Structure Concepts. "We only have one chance to get this right. It's a real good idea. The good part is that it's not too complicated but the bad part is that we have to find a solution to make it cost effective," he admits.
Working on the theory that every millimetre counts in a crash - especially a side-impact crash - the Pulse uses the critical 600m/s time to inflate air pockets in the seat side bolsters.
This pushes people about 50mm in towards the middle of the car, which doesn't sound much, but Prof Dr Schöneburg insists, it is enough to reduce the stresses on the torso by up to a third. Again, the core technology isn't new. Some Mercedes models have had seats with air bolsters in them for years. The new part is linking them into the car's communication systems. It's developed off the E-Class's new seat and the brain that operates it also factors in the steering angle, the cornering force and the speed of the car to judge how much to inflate it.
The seat belt has saved hundreds of thousands of lives since it was invented and, according to Mercedes, it's been improved with three-point mounting, automatic pre-tensioners and belt-force limiters, but the Belt Bag is something new. "The belt bag practically doubles the width of the belt to spread the pressure over a wider area, reducing the risk of injury," Schöneburg explains. "This is particularly beneficial for older passengers, whose ribcages are no longer so flexible." The Belt Bag, developed with Autoliv, has a generator at the edge of the double-layer belt and inflates to around four litres. Mercedes considers that the bag would be most useful in the rear seats, because there is no way to fit frontal airbags there.
Airbags were originally one-size-fits-all, which compromised their safety benefits. While there are adaptive airbags on sale now, the safety prototype's new bags automatically adjust their volume to suit the weight, seating position and stature of the passenger and driver.
The prototype bags have a series of tethers on electric reels. In a crash, the computer tells the bags how much "slack" to let out with the tethers, so they inflate anywhere from 90 to 150 litres. Normal front airbags are about 120 litres.
Mercedes's Pre-Safe has traditionally kept an eye on events in front of a car, but the prototype is constantly checking behind and beside itself as well. It scans up to 60 metres behind the car and brakes the car if it senses a rear-end collision. "Contrary to the widely-held opinion, it does not make sense to take one's foot off the brake pedal before an impending rear-end collision," Schöneburg says. "The correct action is to apply the brakes as hard as possible; however, accident research shows that the driver is moved backwards up to 200mm, which inevitably causes his feet to slip off the pedals. "So we automatically apply the brakes 600m/s before the collision to prevent the car being pushed into traffic or into pedestrians and to minimise the forward acceleration on the occupants."
While Mercedes has only just released its Adaptive High Beam Assist on the E-Class, it's already pushing the technology further. The existing system uses a mechanical rolling screen in concert with infrared cameras to pull the high-beam light cone gradually back towards the light source and always just ahead of the oncoming car.
The new system swaps out existing light technology with LEDs for main headlights which will automatically keep the light cone out of the eyes of oncoming drivers. The ESF 2009's headlights use 100 LEDS each and they can be lit up individually. It also works with the infrared camera in a way the current system can't operate: when the camera picks up a pedestrian or animal in the dark, it can repeatedly flash the lights on the hazard to make sure you see it.
But it's not without its development issues, as Assistance and Safety Systems senior manager, Dr Walter Zeigler, explained. "We will have LEDs as the main lights soon, but the only real problem is cooling them. "We have to keep the temperature at 120-130 degrees. They have a better efficiency than standard, but they still produce heat and they have to be cooled, even at a standstill, so there'll need to be some sort of coolant."
Typical child seats are plastic, but the ESF 2009 uses a new, modular, tubular-based seat, developed with restraint-system specialist, Takata. Suitable from three to 12 years, the height and width can be adapted to suit different children and it has been designed to restrain the child's head and shoulders.
Heard of an ad hoc wireless local area network (WLAN)? These are now used by computers and mobile phones, but Mercedes predicts cars will soon use them to communicate with other cars to warn other drivers about ice, rain, traffic problems, fog or dangerous situations. "It's very important for compatibility that we have a common standard around the world," Schöneburg insists. This is not an exclusively Mercedes feature. Instead, while Mercedes has been working on interactive communication for seven years, it is also working with the rest of the German car industry to come up with a uniform global standard for it. "I hope in five years we will have the first cars with this system on the road. And I hope that in five to 10 years, the first cars will come and then the rest will follow very fast." firstname.lastname@example.org