Advanced emergency brake systems fort rucks can make a major contribution to road safety by effectively helping to prevent accidents caused by heavy trucks. However, the current requirements for these advanced emergency brake systems were established over ten years ago. The state of the art has developed considerably since then. The task of the Federal Highway Research Institute was therefore to check whether the technical requirements for advanced emergency brake systems are still up to date or whether an adaptation would make sense for road safety. Technical progress in the field of driver assistance systems is so great that the requirements for emergency braking systems laid down almost 10 years ago no longer correspond to the state of the art – both with regard to the ability to switch off emergency braking systems, which is explicitly permitted in the currently applicable regulations, and with regard to the required braking performance or speed reduction. First it had to be examined whether the currently permitted manual deactivation is necessary, and if so, whether it can be restricted to certain traffic situations and vehicle types. It was also necessary to examine whether higher minimum deceleration values could be demanded, whether emergency braking with a significantly higher speed reduction could be initiated, particularly in the case of stationary vehicles in front of the vehicle (e.g. at the end of a traffic jam), and whether the systems would also have to be able to detect smaller vehicles than previously prescribed. In emergency braking situations, it is conceivable that drivers could inadvertently override (and thus switch off the emergency braking system), for example by „falling on the pedal“. It should therefore be investigated whether this case is relevant and needs remedial action. Adaptation of the control criteria to different road conditions (low coefficient of friction) and the possibility of warning drivers when safety distances are short should also be examined. In particular, the required automatic speed reductions in the event of impending collisions with stationary targets can be increased significantly. Based on driving dynamics fundamentals, different times for brake interventions were determined, depending on the initial driving speed. As a prerequisite for automatic braking interventions, it was assumed that these are justified at the latest when a human driver no longer has the possibility of avoiding a target object. Measurements show a good correspondence between a simulation model derived from the assumptions and the actual brake intervention times and braking interventions of a truck equipped with a modern emergency braking system. As a result, achievable speed reductions as a function of initial speed and road surface were determined, which are suitable as requirements for international regulations. With regard to the manual deactivation of advanced emergency brake systems, the investigations showed that false warnings during driving cannot be completely avoided, even when using one of the most advanced emergency braking systems currently available. The main reason for this is the insufficient recognizability of driver intention in certain traffic situations. However, false warnings in undisturbed motorway travel (= outside motorway construction sites) could not be found. From a technical point of view, it therefore makes sense to allow the deactivation of an advanced emergency braking system only in those traffic situations in which the system‘s misinterpretation (objects off the carriageway) can lead to malfunctions. An indicator for this can be a certain speed limit. For an additional early warning of the driver if the minimum distance is too small, an improvement in traffic safety is conceivable. However, the actual benefit of a distance warning depends on whether the distance is inadvertently or deliberately kept short and whether truck drivers react to a warning by increasing the distance. (Author/publisher)
Samenvatting