Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle subsystem or accessory control
Reexamination Certificate
2002-11-13
2004-04-20
Nguyen, Thu V. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle subsystem or accessory control
Reexamination Certificate
active
06725141
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method of triggering restraint means in a motor vehicle in the event of an impact and/or a collision with an object. The method primarily relates to the triggering of non-reversible restraint means, such as pyrotechnic seatbelt tighteners and airbags. For this purpose, the time characteristic of the acceleration is detected in the form of at least one acceleration signal. The time characteristic of a velocity is then generated from the acceleration signal. A threshold value for the velocity is determined as a triggering criterion.
BACKGROUND INFORMATION
Conventionally, airbag control devices measure the acceleration in the passenger compartment in the event of an accident and, on the basis of this acceleration, determine when restraint means, such as seatbelt tighteners and airbags, must be triggered.
A method of triggering restraint means in a safety system for vehicle occupants is discussed in European Patent No. 0 458 796, in which an acceleration signal is detected with the aid of a suitable acceleration sensor. Through integration over time, possibly in combination with suitable weighting, this acceleration signal is converted into a velocity. A threshold value is used as a triggering criterion for the velocity. In the method of European Patent No. 0 458 796, the threshold value is determined as a function of one or more state variables or of prior state variables of the motor vehicle. For example, the acceleration signal itself, a signal derived therefrom, such as the velocity, or even the time passing during the crash may be considered as state variables.
The threshold value is selected in the context of the conventional method in such a manner that it ensures safe and reliable triggering of the necessary restraint means in all impact situations coming into consideration, independent of the type of collision partner and the impact velocity, i.e., the relative velocity between the motor vehicle and the collision partner. Dynamic adaptation of the threshold value to the specific impact situation is not possible here, since in this case, neither a suitable sensor system nor a corresponding signal analysis system is provided.
SUMMARY OF THE INVENTION
In accordance with an exemplary embodiment of the present invention, a method is provided in which the triggering of restraint means, such as airbags and seatbelt tighteners, is better adapted to the specific impact situation and unnecessary triggering of restraint means may be avoided.
This may be achieved according to an exemplary embodiment of the present invention in that the impact velocity and the instant of impact are established with the aid of a pre-crash sensor system before the impact. The impact situation is classified with reference to the impact velocity. A triggering time window, in which the time characteristic of the velocity is generated, is determined with the aid of the classification of the impact situation, and, in parallel to this, a threshold value for the velocity is established from the acceleration signal, the classification of the impact situation being taken into consideration.
According to an exemplary embodiment of the present invention, the conventional “single point sensing systems” may be expediently expandable by a pre-crash sensor system to be installed in the motor vehicle in order to detect possible collision partners in the surroundings of the vehicle beforehand. With the aid of the pre-crash sensor system, the impact velocity (closing velocity v
close
) and the instant of impact (t
0
), i.e., the time difference until the impact against the object, may be established. If the pre-crash sensor system includes at least two pre-crash sensors arranged in a suitable manner, the offset, i.e., the impact point and the impact angle, may additionally be determined using a triangulation method. In the context of the pre-crash sensing, radar measurements, infrared measurements, or even optical measurement methods may be used.
Furthermore, according to an exemplary embodiment of the present invention, the impact situations in consideration may expediently be classified with reference to the impact velocity, since the impact velocity alone may provide information about the severity of the crash. The optimum triggering time and the maximum necessary restraint means may be a function of further parameters, such as the type of impact, the mass ratio of the collision partners, and the ratio of the rigidities of the collision partners. Furthermore, the classification of the impact situation on the basis of the impact velocity according to an exemplary embodiment of the present invention may allow the localization to a triggering time window [t
A
. . . t
B
] of the triggering time which is to be established. This may provide the possibility of including information about the course of the crash after instant of impact t
0
until beginning t
A
of triggering time window [t
A
. . . t
B
] in the determination of the threshold value. In addition, the generation of the time characteristic of the velocity from the acceleration signal may now be restricted to the triggering time window.
Additionally, according to an exemplary embodiment of the present invention, it may be expedient to consider the specific impact situation while determining the threshold value from the acceleration signal, since, for example, higher impact velocities may require more sensitive triggering of the restraint means than lower impact velocities. Therefore, according to an exemplary embodiment of the present invention, the classification of the impact situation is also considered while establishing the threshold value.
In an exemplary method according to the present invention, the maximum necessary restraint means in an impact situation are also determined with the aid of the classification of the specific impact situation.
There are various possibilities for classifying the impact situations with reference to the impact velocity. In a variant for two-stage restraint means, velocity clusters in the form of velocity ranges for the impact velocity are formed, the cluster limits being selected according to the respective maximum necessary restraint means. In this case, the velocity clusters are defined as the velocity ranges in which, for all impact situations in consideration,
either no restraint means are necessary (cluster C
0
)
or the first stage of the restraint means is necessary in the belted state for some of the impact situations in consideration, while restraint means are not yet necessary in the belted state (cluster C
1
),
or the first stage of the restraint means is necessary in the belted state for some of the impact situations in consideration, while the second stage of the restraint means is not necessary in the unbelted state or in the belted state (cluster C
2
),
or the first and second stages of the restraint means are necessary in the unbelted state for some of the impact situations in consideration, while the second stage of the restraint means is not necessary in the belted state (cluster C
3
),
or the first and second stages of the restraint means are necessary both in the unbelted state and in the belted state for some of the impact situations in consideration (cluster C
4
).
In the context of the classification of a specific impact situation, the corresponding impact velocity is assigned to one of these velocity clusters. The maximum necessary restraint means may then be determined easily on the basis of the classification of the impact situation and/or the assignment to the corresponding velocity cluster.
The above-described classification of the impact situations may be advantageous because the triggering time window for a specific impact situation may be established easily with the aid of the velocity values which form the cluster limits of the velocity cluster assigned to the corresponding impact velocity.
In the context of an exemplary method according to the present invention, the time characteristic of a velocity is generated from
Nguyen Thu V.
Robert & Bosch GmbH
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