Lane-departure warning system with differentiation between an edge-of-lane marking and a structural boundary of the edge of the lane

A driver assistance device for warning a driver of a motor vehicle of a risk or departure from the road or from the lane in which he is driving, said device comprising:

• at least one image-transmitting sensor,
• a height-estimating sensor,
• an evaluation device, connected to the image-transmitting sensor and the height-estimating sensor, for detecting a structure condition of a road edge and/or a lane edge, comprising:
• means for creating a height profile from measured values of the height-estimating sensor to detect a discontinuity in the height profile, and
• means for detecting a structural boundary at the region of the edge of lane on the basis of a detected discontinuity in the height profile to differentiate between the structural boundary and edge-of-lane markings, indicative of a structure condition of the road edge and/or lane edge;
• a warning device which is connected to the evaluation device, wherein the warning device varies time points of warning output, indicating a risk of departure from the road or from the lane which the vehicle is in, depending on the structure condition of the road edge and/or the lane edge.

A method for operating a driver assistance device for warning a driver of a motor vehicle of a risk of departure from the road or from the lane in which he is driving, the driver assistance device detecting a structure condition of a road edge and/or a lane edge, the method comprising:

• creating a distance and/or height profile from measured values of a distant-transmitting and/or height-estimating sensor for detecting the structure condition of the road edge and/or the lane edge, and
• detecting a structural boundary at the region of the edge of road/lane on the basis of a discontinuity in such a profile to differentiate between the structural boundary and edge-of-lane markings, indicative of the structure condition of the road edae and/or lane edge,
• varying time points of warning output by a warning device depending on the detected structure condition of the road edge and/or the lane edge, wherein
• when there is a road/lane marking, warning the driver of the motor vehicle of a risk of departure from the road or from the lane only when the vehicle enters into contact with or passes beyond the marking, and
• when there is a structural boundary, warning in advance the driver of the motor vehicle of a risk of departure from the road or from the lane before the vehicle enters into contact with the structural boundary.