F2008-08-047
Driver Assistance Systems for Active Safety in Mercedes-Benz Passenger Cars - System Characteristics in the Area of Conflict between Driver Acceptance and System Benefits
The increase in safety in road traffic is of great social importance. After the major progress made in past decades, which are primarily largely attributable to the optimization of passive safety, an integrated safety concept is increasingly coming to the fore. In addition to the established systems of active safety, such as ABS, ESP and BAS, vehicle-sensing systems are gaining in prominence.
The subject of this presentation is driver assistance systems that support the driver in collision prevention through warning and braking. When a hazardous situation is detected, close-proximity radar sensors behind the front bumper and a long-range radar in the radiator grille provide help. They continuously monitor the traffic ahead of the car. The close-proximity radar (24 Gigahertz) works with a range of 30 meters and a scan angle of 80 degrees, and the long-distance radar (77 Gigahertz) has an opening angle of nine degrees and can scan three lanes of a motorway for 150 meters. Uncertainties in environment recognition, and particularly in terms of the driver's intention, lead to conflicts that must be resolved as optimally as possible in the context of system design. On the one hand, in dangerous traffic situations, the driver should experience the greatest possible benefit, and on the other hand, the systems must comply with the driver's wishes at all times. Two system characteristics that usefully complement each other are derived from this area of conflict between driver acceptance and system benefits: an autonomously braking collision mitigation system (CMS) and a situation-adaptive brake assist system. The brake assist system closes the intrinsic loophole of the CMS, thus forming a key element in the development of an integrated safety concept.
With regard to collision prevention with the support of CMS, the effective advance warning time is introduced as a central benefit. This is defined as the timeframe that the driver has from onset of the first acoustic-sensory warning with utilization of the autonomous brake intervention in order to initiate at the latest a maneuver that still prevents the collision. In contrast to the warning-only systems, the autonomous brake intervention results in an additional reaction time gain that is particularly effective if the driver reacts slowly. This gives the driver additional time to take evasive action ahead of the obstacle or to come to a standstill using the situation-adaptive brake assist system. The benefit of the situation-adaptive brake assist system has been impressively demonstrated in road simulator testing.
Session: Driver Assistance II