Motor vehicle with ultrasound-based distance measurement at slow speeds

摘要

The invention relates to a method for operating a driver assistance device (20) of a motor vehicle (10) during a driving operation, in which a driver (12) performs a longitudinal guidance of the motor vehicle (10) itself. The driver assistance device (20) determines in a listening mode in dependence on a sensor signal (U) at least one ultrasonic sensor (18) a distance (D1, D2) to a vehicle external object (34). The invention is based on the task of improving the driver assistance device (20) for collision protection during free travel in a dynamically changing environment. The driver assistance device (20) generates a brake signal (B) for a vehicle brake (22) in a collision protection mode for braking the motor vehicle (10) if the distance (D1, D2) fulfills a predetermined collision criterion. The collision protection mode is only active if a driving speed (V) of the motor vehicle (10) is less than a predetermined Aufschaltwert (V0). On the other hand, the eavesdropping mode is also active if the vehicle speed (V) is greater than the switch-on value (V0).