Method and device for triggering an automatic emergency braking process of a vehicle

A method for triggering automatic emergency braking in a first vehicle to avoid or mitigate the effect of a rear end collision with a second vehicle traveling ahead of the first vehicle, by implementing a predefined emergency braking deceleration, said method comprising:

• determining an instantaneous driving situation of the first vehicle, based on a registered acceleration of the first vehicle;
• determining whether a predefined warning condition is fulfilled based on said instantaneous driving situation of said first vehicle, and on said predefined emergency braking deceleration;
• triggering a driver warning if said predefined warning condition is fulfilled;
• and
• triggering an automatic emergency braking process, which causes said first vehicle to decelerate with the predefined emergency braking deceleration, after the driver warning has been triggered;
• wherein,
• the warning condition includes, as target conditions, a predefined target safety distance and a predefined target relative speed between the first and second vehicles, which are to be attained after said automatic emergency braking process is completed;
• in determining the instantaneous driving situation of the first vehicle, in addition to the registered acceleration of the first vehicle, a registered current relative acceleration between the first and second vehicles is also taken into account;
• triggering of said automatic emergency braking process is delayed until expiration of a predefined warning time period after the driver warning has been triggered;
• the driver warning comprises at least two warning stages which are triggered in chronological succession within the predefined warning time period of the driver warning;
• each warning stage is assigned a predefined warning stage time period;
• the warning stage time period is predefined in a permanent or adjustable fashion;
• and
• after a first warning stage has been triggered, at least one further warning stage is triggered only if a predefined warning stage condition assigned to the further warning stage is fulfilled.

Apparatus for carrying out automatic emergency braking in a first vehicle to avoid, or mitigate the effects of, a rear end collision with a second vehicle traveling ahead of the first vehicle by implementing a predefined emergency braking deceleration, said apparatus comprising an evaluation unit which triggers a driver warning when at least one predefined warning condition stored in the evaluation unit is fulfilled;

• wherein:
• an instantaneous driving situation of the first vehicle is determined based on a registered acceleration of the first vehicle;
• fulfillment of the warning condition requires that, based on the instantaneous driving situation of the first vehicle, and on said predefined emergency braking deceleration, an automatic emergency braking process which causes the vehicle to decelerate with the predefined emergency braking deceleration, is to be triggered by suitable actuation of braking means of the vehicle;
• the warning condition includes, as target conditions, a predefined target safety distance and a predefined target relative speed between the first and second vehicles, which are to be attained when said automatic emergency braking process is completed;
• in determining the instantaneous driving situation of the first vehicle, in addition to the registered acceleration of the first vehicle, a registered current relative acceleration between the first and second vehicles is taken into account;
• said automatic emergency braking process is triggered only after the driver warning has been triggered and a predefined warning time period has expired thereafter.