DE102005012949A1 - Pedestrian and motor vehicle collision recognizing method for motor vehicle`s safety system, involves differentiating collisions by determining collision relative velocity based on time lag and discriminating velocity based on fixed value - Google Patents

Abstract

The method involves detecting collisions and generating signals corresponding to the collisions by sensors (6, 6`, 7). A time lag is determined between time points of exceedance of signals of respective sensors, where signals have respective preset threshold values. The collisions are differentiated by determining a collision relative velocity based on the time lag, where the velocity is discriminated based on a fixed value or sample. An independent claim is also included for a device for recognizing a pedestrian collision for a safety system of a motor vehicle.

Description

The The present invention relates to a method and an apparatus for distinguishing impact types, in particular for detecting a pedestrian impact, for a Security system of a motor vehicle with at least one control unit and at least a first sensor and a second sensor and a detection device to.

sensors be for Safety systems in motor vehicles in different versions, for example as acceleration sensors, for the function of crash sensors u. a. for detecting side impacts, Front crashes or to detect impact severity in the front area used for years. Contact sensors are used in the Vehicle for the use in active pedestrian protection.

For illustration, the documents DE 100 30 465 A1 and DE 102 31 364 A1 called.

Especially the discrimination of a pedestrian with other impact objects presents the development of a contact sensor algorithm considerable Obstacles. Previous systems - except those with forward-looking sensors - can one other parameters for discrimination, for example the relative speed, early enough before a trigger decision only insufficiently determined.

ADVANTAGES OF INVENTION

The inventive method and the device according to the invention for distinguishing impact types, in particular for detecting a pedestrian impact, for a Security system of a motor vehicle allow in contrast with the features of claim 1 and 6 by determining a time difference of time-shifted sensor signals early discrimination of the Impact type, as well as by simultaneously processing the time-shifted sensor signals an early one Determining the impact severity by comparing the processed signals with a relative Be subtracted.

from that There is the advantage that security means at different Impact speeds can be adjusted so targeted that They each develop their optimal safety effect.

The The basic idea of the invention is that two time-shifted sensor signals geometrically in the direction of impact successively arranged sensors be recorded in their time interval, the time offset as a measure of discrimination is used by means of a collision relative speed. One Simultaneous processing of the sensor signals and determining a relative difference is in addition to the determination of a Impact severity used. Here, this relative difference is reversed proportional to the impact severity.

One Method for distinguishing impact types, in particular for Detecting a pedestrian impact, for a Security system of a motor vehicle with at least one control unit and at least a first sensor and a second sensor comprises the following method steps:

(S1) Detecting an impact and generating corresponding thereto respectively Signals through at least a first sensor and a second sensor;

(S2) Determining a time difference between the time of exceeding the signal of the first sensor of a first predetermined threshold and the time of exceeding the signal of the second sensor of a second predeterminable threshold value; and

(S3) Discriminating an impact type by determining a relative impact velocity based on the time difference and discriminating the impact relative velocity based on a fixed value or pattern.

Thereby is a simple and above all cost-effective extension of a contact sensor system, the one restriction the degrees of freedom by determining an additional physical quantity like the Relative speed, mass of the impact object and impact location allows a considerable one Improvement of the discriminating ability between a pedestrian and other objects.

In an embodiment in step (S2) the impact relative velocity based on the time difference and a distance between the installation locations the at least one first sensor and the second sensor determined. By this advantageously simple calculation time is saved and the for the triggering algorithm required supporting Value becomes early provided.

For this purpose, it is preferred that the second sensor is arranged in a vehicle longitudinal axis or a vehicle transverse axis behind the first sensors, resulting in a fixed geometric value he which can be used to calculate a relative impact speed.

In A further embodiment provides that the method step (S2) has the following substeps:

(S2-1) Editing the sensor signals and forming a relative difference of processed sensor signals of the first and second sensors by dividing by the absolute value of a processed sensor signal; and

(S2-2) Determining a collision severity based on the relative difference of processed signals.

in this connection it is preferred that in the sub-step (S2-1) editing the Sensor signals as integrating takes place.

Thereby is it additional possible, the triggering algorithm further information early for one triggering decision the security agent available to deliver. It is also advantageous that this information be obtained from the existing sensor signals.

In In another embodiment, the impact severity is after the impact begins first within the time difference as easily assumed, wherein after occurrence the second sensor signal directly determining the impact severity based on the relative difference between the processed signal values. By Simultaneous calculation of the impact severity will be the triggering algorithm another value early to pass advantageous quick decision making, thereby triggering the decision becomes considerably safer.

A Device for distinguishing impact types, in particular for Detection of a pedestrian impact, for a Security system of a motor vehicle with at least one control unit and at least a first sensor and a second sensor, characterized that at least one first sensor at a distance in a vehicle longitudinal axis or in a vehicle transverse axis in front of at least one second sensor is arranged.

Of the at least one first sensor is in a panel in front of the second Sensor arranged, wherein the second sensor mounted on a support is, where the carrier, on which the second sensor is mounted, a greater rigidity as the cladding has. It is preferred that the second Sensor as a structure-borne sound sensor or is designed as a kinematic sensor.

In a further embodiment indicates the controller a detection device for distinguishing impact types and for determining the impact severity, wherein a preferred From design provides that the detection device as a component a software of the control unit is trained. This results in an advantageous space saving instead of a separate attachment.

• – einen ersten und zweiten Vergleicher zum Vergleich von ersten und zweiten Sensorsignalen mit einem vorgebbaren Schwellwert;
• – eine erste Auswerteeinrichtung zur Bildung einer Zeitdifferenz zwischen dem Zeitpunkt des Überschreitens des ersten Sensorsignals des ersten vorgebbaren Schwellwertes und dem Zeitpunkt des Überschreitens des zweiten Sensorsignals des zweiten vorgebbaren Schwellwertes zur Ermittlung einer Aufprallrelativgeschwindigkeit anhand der Zeitdifferenz und eines Abstands zwischen den ersten und zweiten Sensoren;
• – eine Diskriminiereinrichtung zur Unterscheidung der Aufprallart anhand der Aufprallrelativgeschwindigkeit durch Vergleich mit einem vorgebbaren Wert oder Muster;
• – eine erste und zweite Bearbeitungseinrichtung zur Bearbeitung der Sensorsignale;
• – eine zweite Auswerteeinrichtung zur Bildung einer relativen Differenz der bearbeiteten Sensorsignale des ersten und zweiten Sensors durch Division durch den Absolutbetrag eines bearbeiteten; und
• – eine dritte Auswerteeinrichtung zur Bestimmung der Aufprallschwere anhand der relativen Differenz der bearbeiteten Signale.

A detection device for distinguishing impact types and for determining impact severity comprises:

• - A first and second comparator for comparing first and second sensor signals with a predetermined threshold value;
• - A first evaluation device for forming a time difference between the time of exceeding the first sensor signal of the first predetermined threshold and the time of exceeding the second sensor signal of the second predetermined threshold for determining a relative impact speed based on the time difference and a distance between the first and second sensors;
• A discriminating device for distinguishing the type of collision on the basis of the collision relative speed by comparison with a predefinable value or pattern;
• - First and second processing means for processing the sensor signals;
• A second evaluation device for forming a relative difference of the processed sensor signals of the first and second sensors by dividing by the absolute value of a processed one; and
• - A third evaluation device for determining the impact severity based on the relative difference of the processed signals.

It is preferred that the first and second processing device ( 13 . 14 ) is designed for integration of the sensor signals.

advantageous Embodiments and developments of the invention are the dependent claims and the Description with reference to the drawings removable.

DRAWINGS

The Invention will be described below with reference to the figures in the drawing specified embodiments explained in more detail.

It shows:

1 a schematic representation of an embodiment of a Vor invention direction in a motor vehicle;

2 a block diagram of a detection device according to the invention; and

3 a graphical representation of processed sensor signals to determine an impact severity.

DESCRIPTION THE EMBODIMENTS

Triggering algorithms for restraint systems from Vehicles, for example airbags, evaluate acceleration signals from Sensors in a control unit or central unit as well as the acceleration signals from one or more sensors in the deformation area of a vehicle, so-called upfront sensors in the front, in a collision or impact or Crash out.

One pedestrian protection for example, by constructive measures on the vehicle front considered, so that the impact hardness of endangered Body parts like head or legs, is diminished. One way the risk of injury too In particular, the reduction exists in the creation of free space between the "soft" bonnet and the hard engine components to extend the deformation path during the impact. This can be done by changing the design, or by an active system, which by means of a sensor the Impact sensed and then the necessary Deformationsweg example, by rapid lifting of the hood guaranteed.

The Sensation of a pedestrian impact requires a reliable one Sensors on the front of the vehicle (i.e., bumpers or cross members) that a quick decision to control the respective security means guaranteed and a safe distinction between triggering and non-triggering cases allows. In particular, this requires a sensor system that detects object discrimination or Differentiation of impact types and beyond certain parameters of the impacting object (mass, relative velocity, etc.) for characterization the impact severity recognizes.

For this Acceleration sensors but also knock sensors are suitable in the bumper fascia especially good as a sensor to sense a pedestrian impact.

1 shows a schematic representation of an embodiment of a device according to the invention 1 for distinguishing types of impact, in particular for detecting a pedestrian, in a motor vehicle 2 , The car 2 is shown only with its front area. In a bumper cover 3 is at least a first sensor 6 . 6 ' arranged. Two first sensors are preferred 6 . 6 ' , the side by side or at a distance from each other across the width of the bumper fascia 3 can be distributed. Behind this first sensor 6 . 6 ' is an additional, second sensor in the direction of a vehicle longitudinal axis 7 arranged, which on a cross member 4 is attached. Between the bumper cover 3 and the cross member 4 a so-called impact damper, for example made of foam, may be present.

The sensor 6 . 6 ' . 7 is to a detection device 20 a control unit 5 a safety system of the motor vehicle 2 for retaining means, such as airbags, belt tensioners, pedestrian airbags and the like, connected. The at least one first sensor 6 . 6 ' For example, it is designed as a known acceleration sensor. The second sensor 7 may be a structure-borne sound sensor, for example, a so-called knock sensor or a magnetostrictive sensor, or be designed as a kinematic sensor, for example, an acceleration sensor.

In a frontal collision, one of the first two sensors delivers 6 . 6 ' or both, a first sensor signal 18 (please refer 2 ). The impact object deforms the bumper cover 3 , which absorbs energy, and the muffler, until that the second sensor 7 on the cross member 4 is reached. The crossbeam 4 has a greater rigidity than the bumper fascia 3 , In this case, the second sensor generates 7 a second sensor signal 19 (please refer 2 ), which with a certain time delay after the first sensor signal 18 occurs.

For further explanation of the operation reference is made to 2 and 3 taken.

2 shows a block diagram of a detection device according to the invention 20 ,

The time-shifted sensor signals generated during the impact 18 . 19 are each in a first and second comparator 8th . 9 compared with a predetermined threshold to prevent false triggering in a known manner. The then detected as actual impact signals sensor signals 18 . 19 are now on the one hand a first evaluation 10 and at the same time a first and a second processing device 13 . 14 fed.

First, the first evaluation device 10 explains which of the times at which the sensor signals 18 . 19 occur, a time difference .DELTA.t determined. The time difference Δt is the time delay with which the second sensor signal 19 of the second sensor 9 occurs during impact. She is characteris table for a relative impact speed of the impact object.

With the known distance of the second sensor 7 to the first sensor 6 . 6 ' , the first sensor signal 18 has now been calculated with the time difference .DELTA.t the impact relative velocity of the impact object in a known manner. Then this will be to a subsequent discriminating device 11 passed on, for example, based on a comparison with a predetermined value or a predetermined pattern, the value of the impact relative velocity in a suitable form as a data value of an impact type AA to a triggering algorithm of the control unit 5 passes.

Of the triggering algorithm receives with the data value of the impact type AA, an advantageously fast discrimination aid, whether the impact detected is a pedestrian impact or another object. In the case of a pedestrian can the triggering algorithm targeted the for a pedestrian impact provided safety means in the area of the detected impact location trigger in time.

Another support for the triggering algorithm is the simultaneous processing of the sensor signals 18 . 19 by the first and second processing means 13 . 14 , which is described below.

The first and second processing device 13 . 14 performs a processing of the two time-shifted sensor signals 18 . 19 by preferably integrating them. From the data values of processed sensor signals 21 . 22 (please refer 3 ), a difference is then formed, which is then determined by the absolute value of the integral of one of the two processed sensor signals 21 . 22 divided. This is preferably the first processed sensor signal 21 , since this value is available first. In this way, a relative difference is formed which is indirectly proportional to an impact severity. After the impact begins, the impact is initially considered to be a slight impact. As soon as the second sensor signal 19 in processed form 22 is present, the direct calculation of the impact severity takes place in the second evaluation device 15 , A suitable data value can be determined by means of a third evaluation device 16 as the impact severity AS to the triggering algorithm in the controller 5 be handed over.

3 shows a graphical representation of a first and second processed sensor signal 21 . 22 as integral over a time t. There are two pairs of processed sensor signals 21 . 22 and 21 ' . 22 ' shown. The processed sensor signals 21 . 22 are characteristic of a slight impact, the processed sensor signals 21 ' . 22 ' for a heavy impact. It can be seen that the integrated signals have a lower slope in a slight impact than in a heavy impact. Also, there is a difference in the time-delayed occurrence of the respective second processed signals, namely, a time difference Δt ₂ in the light impact and a time difference Δt ₁ in the heavy impact. The impact severity is thus recognizable by the length of the time difference, the shorter it is, the heavier the impact.

Thus, the triggering algorithm of the controller receives 5 Accurate information on impact relative velocity and impact severity early in the event of a collision, by means of which it can purposefully trigger the safety means which are required, for example, particularly in the case of a pedestrian impact.

The The invention is not limited to the embodiments described above limited, but on diverse Modifiable manner.

For example, it is conceivable that the arrangement of a first sensor 6 . 6 ' and a second sensor 7 can also be made at the rear of the vehicle and on the sides. Here is the second sensor 7 each in the direction of impact behind the first sensor 6 . 6 ' to be arranged, wherein a support element of the second sensor 7 has a greater rigidity than the cladding, in which the first sensor 6 . 6 ' is arranged. This fairing can be at the rear as well as at the front of a bumper fascia, which may be on the sides of a door trim.

The recognition device 20 may be a first and second storage device 12 . 17 for storing default values, patterns and tables that can be used for the appropriate data value formation of the impact type AA and impact severity AS. Predefinable setpoint values can also be stored therein.

The recognition device 20 can be separated from the control unit 5 be educated. But it can also be part of a software of the control unit 5 be.

The sensors 6 . 6 ' . 7 can be different types, whereby the calculation method of the integrals is suitably adapted in each case (integration of the absolute value).

A processing of the sensor signals in the first and second processing means 13 . 14 can also be done with other editing methods in addition to or instead of integration become.

There may also be multiple pairs of first and second sensors 6 . 6 ' . 7 be provided in the respective impact areas on the vehicle.

Claims (12)

Method for distinguishing impact types (AA), in particular for detecting a pedestrian impact, for a safety system of a motor vehicle ( 2 ) with at least one control unit ( 5 ) and at least one first sensor ( 6 . 6 ' ) and a second sensor ( 7 ), comprising the following method steps: (S1) detecting an impact and generating corresponding signals ( 18 . 19 ) by at least one first sensor ( 6 . 6 ' ) and a second sensor ( 7 ); (S2) determining a time difference (Δt ₁ , Δt ₂ ) between the time of exceeding the signal ( 18 ) of the first sensor ( 6 . 6 ' ) of a first predefinable threshold and the time of exceeding the signal ( 19 ) of the second sensor ( 7 ) of a second predetermined threshold value; and (S3) discriminating an impact type (AA) by determining a relative impact velocity based on the time difference (Δt ₁ , Δt ₂ ) and discriminating the relative impact velocity based on a fixed value or pattern. Method according to Claim 1, characterized in that, in method step (S3), the relative impact speed is determined on the basis of the time difference (Δt) and a distance between the installation locations of the at least one first sensor ( 6 . 6 ' ) and the second sensor ( 7 ), the second sensor ( 7 ) in a vehicle longitudinal axis or a vehicle transverse axis behind the at least one first sensor ( 6 . 6 ' ) is arranged. Method according to Claim 1 or 2, characterized in that the method step (S2) has the following substeps: (S2-1) processing of the sensor signals ( 18 . 19 ) and forming a relative difference of processed sensor signals ( 21 . 21 ' . 22 . 22 ' ) of the first and second sensors ( 6 . 6 ' . 7 ) by dividing by the absolute value of a processed sensor signal ( 21 . 21 ' . 22 . 22 ' ); and (S2-2) determining an impact severity (AS) based on the relative difference of the processed signals ( 21 . 21 ' . 22 . 22 ' ) A method according to claim 3, characterized in that in the sub-step (S2-1) the processing of the sensor signals ( 18 . 19 ) as integrating. Method according to Claim 3 or 4, characterized in that, in the partial step (S2-2), after the start of the impact, the impact severity (AS) is initially assumed to be light within a time difference (Δt ₁ , Δt ₂ ), whereby after the second sensor signal ( 19 ) the direct determination of the impact severity (AS) on the basis of the relative difference between the processed signal values ( 21 . 21 ' . 22 . 22 ' ) he follows. Contraption ( 1 ) for distinguishing impact types (AA), in particular for detecting a pedestrian impact, for a safety system of a motor vehicle ( 2 ) with at least one control unit ( 5 ) and at least one first sensor ( 6 . 6 ' ) and a second sensor ( 7 ), characterized in that at least one first sensor ( 6 . 6 ' ) at a distance in a vehicle longitudinal axis or in a vehicle transverse axis in front of at least one second sensor ( 7 ) is arranged. Contraption ( 1 ) according to claim 6, characterized in that the at least one first sensor ( 6 . 6 ' ) in a panel in front of the second sensor ( 7 ), the second sensor ( 7 ) is mounted on a support, wherein the support on which the second sensor ( 7 ) is mounted, has a greater rigidity than the cladding. Contraption ( 1 ) according to claim 6 or 7, characterized in that the second sensor ( 7 ) is designed as a structure-borne sound sensor or as a kinematic sensor. Contraption ( 1 ) according to one of claims 6 to 8, characterized in that the control unit ( 5 ) a recognition device ( 20 ) for distinguishing impact types (AA) and for determining the impact severity (AS). Contraption ( 1 ) according to one of claims 6 to 9, characterized in that the recognition device ( 20 ) as part of a software of the control unit ( 5 ) is trained. Detection device ( 20 ) for distinguishing impact types (AA) and for determining the impact severity (AS) with: - a first and a second comparator ( 8th . 9 ) for comparing first and second sensor signals ( 18 . 19 ) with a predefinable threshold value; A first evaluation device ( 10 ) for forming a time difference (Δt ₁ , Δt ₂ ) between the time of exceeding the first sensor signal (Δt ₁ , Δt ₂ ) 18 ) of the first predefinable threshold and the time of exceeding the second sensor signal ( 19 ) of the second predefinable threshold value for determining an impact relative velocity on the basis of the time difference (Δt ₁ , Δt ₂ ) and a distance between the first and second sensors ( 6 . 6 ' . 7 ); - a discriminating device ( 11 ) to distinguish the type of impact (AA) on the basis of the relative impact speed by comparison with a predefinable value or pattern; A first and a second processing device ( 13 . 14 ) for processing the sensor signals ( 18 . 19 ) of the first and second sensors ( 6 . 6 ' . 7 ); A second evaluation device ( 15 ) for forming a relative difference of the processed sensor signals ( 21 . 21 ' . 22 . 22 ' ) of the first and second sensors ( 6 . 6 ' . 7 ) by dividing by the absolute value of a processed sensor signal ( 21 . 21 ' . 22 . 22 ' ); and - a third evaluation device ( 16 ) for the determination of the impact severity (AS) on the basis of the relative difference of the processed signals ( 21 . 21 ' . 22 . 22 ' ). Detection device ( 20 ) according to claim 11, characterized in that the first and second processing means ( 13 . 14 ) for the integration of the sensor signals ( 18 . 19 ) is trained.