The preventive occupant protection system PRE-SAFE® activates a number of safety systems if an accident appears to be unavoidable. Fortunately, many drivers never find themselves in a situation where they can experience PRE-SAFE® for themselves. A realistic impression of these safety systems is provided by an innovative PRE-SAFE Demonstrator, which will have its world premiere at the 21st ESV Conference in Stuttgart on 15 June.

For the first time for this purpose, the simulator uses a linear motor to accelerate the vehicle cabin to up to 16 km/h within a distance of four metres. This corresponds to an acceleration of two g, i.e. twice freefall speed. After around 1.2 seconds the cabin impacts the specially designed hydraulic shock absorbers. In the interim the occupants not only experience the effects of the PRE-SAFE® functions at first hand, e.g. belt pretensioning, NECK-PRO and the inflatable side bolsters on the seats, but also the restraining effect of the seat belts during the impact.

The linear drive of the PRE-SAFE Demonstrator, which is similar to that of the Transrapid train system, has a power consumption of 10 kW, is freely programmable and also works in the opposite direction. This enables various acceleration profiles, and also a rear-end collision, to be demonstrated. The cabin can also be rotated by 30 degrees on its sledge to simulate an oblique impact. If the cabin is rotated by 90 degrees, the drive system can be programmed a produce to-and-fro motion that gives the impression of taking corners at high speed.

The moving mass of the Demonstrator is 500 kg. This includes the cabin, which was created from a real S-Class saloon whose front passenger seat, dashboard and door were adopted. To keep the Demonstrator compact in size, the driver's side, engine compartment and the body section to the rear of the B-pillar were removed. Specially designed plastic components close off the cabin at these points. The Demonstrator weighs a total of around 2.5 tonnes, and is designed to be easily loaded onto a vehicle by fork-lift truck. Easy transport is also facilitated by the double electrical interfaces directly on the Demonstrator and at the control console. The unit has hydraulically extendable rollers to allow precise placement at the destination.

The PRE-SAFEDemonstrator was developed and designed on behalf of the
Mercedes accident research department by the prototype production function of MB-technology GmbH. The MBtech Group is a globally operating automotive engineering and consulting business within the Daimler group. Project manager Markus Pscheidt recalls: "This commission was a very special challenge, for as far as we were aware, a linear drive system had never been used for automotive purposes. To ensure the safety of the cabin's occupants under all circumstances, we had to design many of the features ourselves in close consultation with the TÜV safety inspectorate."