Daimler SLK – the electronic roadster
Daimler points out that safety was the Leitmotiv for the combination of many different assistant systems; some of them are used for the first time in such a vehicle. For example, the roadster is equipped with a novel drowsiness detection system.
Unlike other systems, it does not watch the driver with a camera and evaluates the activities of his eyes. Instead, the system detects drowsiness and increasing inattentiveness by considering the style of driving. At the beginning of every ride, the system determines an individual profile of the driver’s behaviour. Throughout the travel, this profile is continuously compared against current activities and reaction times. In order to do so, it processes data from steering movements, reaction times and control usage. Other factors taken into account are speed, lateral acceleration / deceleration, side wind, road condition, time of the day and duration of the trip. If the system detects typical indicators for driver’s fatigue, it issues an optical and acoustical warning.
The Speed Limit Assist utilizes a camera on the inside of the windscreen to detect speed limit signs. The system makes use of image processing algorithms; if it "sees" such a road sign, it indicates the speed limit in the instrument cluster or central display.
An advanced adaptive cruise control system utilizes three radar systems, acting at different ranges (30m, 60m, 200m). It works at speeds of up to 200 km/h and warns the driver if the distance to the vehicle in front decreases too fast and too far. If the system figures that a collision is highly probably it computers the brake pressure necessary to prevent the accident. 1.6 seconds before the computed impact time it applies 40 percent of the brake power; issues a haptic warning to the driver and triggers the Pre-safe function. 0.5 seconds before the impact it applies maximum braking power.
The ‘Pre-safe’ functions are intended to mitigate the consequences of an imminent accident. The function is activated if the vehicle is understeering or oversteering, if the Pre-safe brake is triggered or if the driver performs an emergency brake. It also will be triggered if the optional radar-based rear-view brake assist detects an imminent rear-end collision. In all of these cases, the Pre-safe system brings electrically adjustable passengers seat into a more favorable accident position in order to provide optimum protection by seat belts and airbages. In addition, the system begins to close the side windows as well as the sliding sunroof, if applicable.
Another innovation is the "Magic Sky Control" which controls the degree of transparency of the roof. A voltage of 120V controls the alignments of iodine crystals embedded in tha the glass material of the roof. Without voltage, the crystals are aligned randomly, preventing light from passing through the roof. As soon as the voltage is applied, the crystals are aligned in the same direction, allowing the light to pass. According to Daimler, the on/off ratio for the light intensity is 20:80.
The infotainment system is widely configurable, as it is the case at all cars of this class. In the infotainment domain, the MOST bus is used to interconnect the systems. Here is the only place where Daimler did not make use of the latest and most powerful technology: Instead of the MOST150 version, the SLK makes use of the MOST25 version. This circumstance however, is owed to the ultra-recent availability of MOST150. At the time the designers layed out the electronic systems for the SLK, the latest version has not been available yet.