DE102004036833A1 - Apparatus and method for generating a triggering criterion for an impact protection system of a vehicle - Google Patents

Abstract

The invention relates to a device for generating a triggering criterion for an impact protection system of a vehicle with an impact sensor unit (2) comprising a vehicle outer skin part (2.1) which can change its position relative to a vehicle chassis due to a force acting on the vehicle outer skin part (2.1), and at least two sensors (2.2), which are provided for detecting a force acting on the vehicle outer skin part and each force at least provide a sensor output signal (2.3) comprises. Furthermore, a processing unit (3) is provided for evaluating the at least two sensor output signals (2.3). Based on the time profile of the sensor output signals (2.3), the processing unit (3) prescribes a classification of a collision object and generates a triggering criterion (6) for the impact protection system depending thereon. The classification of the collision object improves the decision making to generate a triggering criterion and thus prevents false triggering of the impact protection system, which may cause additional damage under certain circumstances.

Description

The The invention relates to a device for generating a triggering criterion for a Impact protection system of a motor vehicle according to the preamble of claim 1 and a corresponding method according to the preamble of claim 13th

such Impact protection systems should be the consequences of a collision a motor vehicle with a collision object, in particular with a pedestrian, mitigate. For this example, adjustable hoods or airbags in Front area, so-called pedestrian airbags, used. These systems need an impact detection sensor which, in the event of an impact, is a triggering request sends to the impact protection system. Problematic with such Systems is that a trigger the impact protection system, for example, the pedestrian airbag, only in an actual Clash with a pedestrian should, not in a clash with a hard object like a tree or another vehicle.

Around the possible Collision with a collision object as early as possible to be recognized so-called precrash sensors used, which are usually several Have front, rear and side sensors to the speed of the Vehicle and the speed and distance to other vehicles and identify objects. To detect an impact now common optical sensors, in particular based on optical waveguides, used. In addition, show usually the areas in which the Crash Detection attached sensors or impact sensors are, for example the bumper, a deformation area for absorption and detection of acting forces on.

Especially However, optical fiber-based systems are often susceptible to environmental influences. moreover is not an exact determination of the collision object, in particular none accurate distinction between pedestrian and other objects, For example, a tree or a shopping cart, possible.

task The present invention is therefore an apparatus and a Method for generating a triggering criterion for an impact protection system propose a vehicle suitable for the accident better estimate and the impact protection system better suited to the accident circumstances, in particular in a collision with a pedestrian, adapt.

These The object is achieved by a device for generating a triggering criterion for a Impact protection system of a vehicle with the features of claim 1 and by a corresponding method having the features of claim 13 solved. Preferred embodiments of the invention will become apparent from the dependent claims.

One essential idea of the invention is based on the temporal Evaluation of sensor output signals from crash detection sensors a classification of the collision object, in particular with regard to Mass and hardness make. It has been shown that clashes with a soft object like a pedestrian another characteristic waveform of Chrasherkennungssensors revealed as clashes with hard ones Objects like a tree. Similarly, the waveforms of a Chrasherkennungssensors in collisions with heavy or light Objects. The invention thus uses characteristic differences the crash sensor signal waveforms, the in collisions of light and heavy or hard and soft objects occur to one better adapted to the accident triggering an impact protection system to ensure.

The The invention relates to a device for generating a triggering criterion for a Impact protection system of a vehicle with a crash sensor unit, the one vehicle skin part, its position relative to a vehicle chassis due to a can change the force acting on the vehicle chassis, and at least two sensors for detecting one on the vehicle skin part acting force are provided and in each case at least one sensor output signal deliver, includes. Furthermore, a processing unit for evaluation the at least two sensor output signals provided. The processing unit is now designed to be based on the time course the sensor output signals a classification of a collision object make and depend on it a triggering criterion for the Can generate or influence the impact protection system. By the Classification of the collision object, for example, the collision with a Pedestrian relative be reliably recognized. The temporal evaluation of the sensor output signals therefore improves the decision making to generate a triggering criterion or influencing an already existing triggering criterion, e.g. a threshold adjustment. This prevents unnecessary or even undesirable false alarms Impact protection system, which may cause additional damage can.

Especially the classification comprises a determination of the mass of the collision object. In order to can be a clash with a light object like a pedestrian from a collision with a heavy object like another vehicle can be distinguished.

Farther The classification can be a determination of the hardness of the collision object include. This can be a collision with a soft object how to distinguish a pedestrian from a clash with a rigid or hard object like a tree.

By the combination of the classification features mass and hardness can For example, the collision with a shopping cart, the is a light but rigid object, from a collision with a Pedestrian, too a light one, for that but soft object is to be distinguished.

In a preferred embodiment the processing unit is designed to operate on an increase in the waveform of the time history of the sensor output signals classify the collision object as a hard object when the Amount of increase is greater as a first predetermined slope value.

The Processing unit can also be formed to be at an increase in the waveform of the time course the sensor output signals to the collision object as a soft object classify if the amount of the increase is less than one second predetermined rise value ,.

Of the first and second predetermined slope values may be identical. In order to all collision objects will either be in the soft category Objects or the category of hard objects. Fall whereas the first and second predetermined slope values diverge i.e. the second predetermined slope value is smaller than the first one given rise value, can those slope values of the sensor output signals falling within one range fall between the first and second predetermined slope values, can not be clearly assigned to a category. Non-assignable sensor output signals should, for example, when forming or influencing the triggering criterion (for example, at a threshold adjustment) are disregarded.

The Processing unit is in a preferred embodiment designed to be at an amplitude in the waveform of the temporal History of the sensor output signals the collision object as heavy Classify an object when the magnitude of the amplitude is larger as a first predetermined amplitude value.

Farther For example, the processing unit may be formed at an amplitude in the waveform of the time course of the sensor output signals the To classify collision object as a light object when the Amount is smaller than a second predetermined amplitude value.

Of the first and second predetermined amplitude values can here also be identical. This will either collision objects a category of light objects or heavy category Assigned objects. The first and second predetermined amplitude values can but also fall apart, i. it may be the second predetermined Amplitude value to be smaller than the first predetermined amplitude value; then can those amplitude values of the sensor output signals which are in one Range between the first and the second predetermined amplitude value fall, can not be clearly assigned to a category. These signals should then be discarded, i. not for production or influence a triggering criterion be used.

In a preferred embodiment the processing unit is designed to provide an additional Speed signal of the vehicle or an additional Signal of the relative speed of the vehicle to the collision object to process and adjust the classification accordingly. It has been found to be a higher vehicle speed or a higher relative speed between vehicle and collision object usually both to one higher amplitude as well as a steeper increase in the time course lead the sensor output signal in a crash. With the processing an additional one Speed signal can the given slope and amplitude values to the velocity of the vehicle or the relative speed of the vehicle to Collision object dynamically adjusted. This will become a reliable classification of the collision object and a better assessment of the accident.

typically, the device is characterized in that one or more the at least two sensors for generating the at least two sensor signals Pressure or acceleration sensors are. Alternatively or additionally, one can or more of the at least two sensors may be strain gauges.

Furthermore, the invention relates to a method for generating or influencing a triggering criterion for an impact protection of a vehicle, in which an impact sensor unit, which consists of a driving outer skin part which changes its position relative to a vehicle chassis due to a force acting on the vehicle outer skin part, and at least two sensors provided for detecting a force acting on the vehicle skin part provides at least two sensor output signals, and wherein one processing unit outputs the at least two sensor output signals evaluated over time. Based on the time profile of the sensor output signals, the processing unit prescribes a classification of a collision object and generates or influences a triggering criterion for the impact protection system depending thereon.

Especially the classification of the collision object is performed by a determination the mass of the collision object. This can be a light collision object like a pedestrian of distinguished a heavy collision object as another vehicle become.

The Classification of the collision object can also be determined by a determination the hardness of the Collision object done. This can be a soft collision object like a pedestrian of a hard collision object such as a tree can be distinguished. A combination of the classification features mass and hardness can further improve the classification of the collision object. One For example, a light, soft object like a pedestrian can distinguished from a light but hard object like a shopping cart become.

The Processing unit may continue to rise in the waveform the temporal course of the sensor output signals the collision object classify as a hard object if the amount of the increase is greater as a first predetermined rise value, whereas when rising in the waveform of the time history of the sensor output signals the collision object is classified as a soft object when the amount is less than a second predetermined rise value.

Of the first and second predetermined slope values are the simplest Case identical. This is an unambiguous assignment of the collision object in the category of soft objects or hard category Objects possible. If the first predetermined slope value is smaller than the second predetermined one Rise value, can those slope values of the sensor output signals, which in one Range between the first and the second predetermined slope value fall, can not be clearly assigned to a category. by virtue of For example, the missing assignment can be the triggering criterion be deactivated.

In addition, can the processing unit the collision object as a heavy object classify when the waveform of the timing of the sensor output signals has an amplitude whose magnitude is greater than a first predetermined one Amplitude value. Similarly, a collision object becomes light Object classifies when the waveform of the time course the sensor output signals has an amplitude whose magnitude is smaller than a second predetermined amplitude value.

Analogous the given rise values are the first and the second predetermined amplitude value identical in the simplest case. In order to is a unique assignment of the collision object to the category light objects or heavy objects category possible. If the first predetermined amplitude value is smaller than the second one predetermined amplitude value, can those slope values of the sensor output signals that are in the range fall between the first and second predetermined slope values, can not be clearly assigned to a category. Again, you can due to the missing assignment, for example, the triggering criterion be deactivated.

In a preferred embodiment the processing unit processes an additional speed signal of the vehicle or an additional one Signal of relative velocity of vehicle and collision object and adjusts the classification accordingly. A higher speed of the vehicle or a higher Relative speed between vehicle and collision object leads in the Usually in a crash to a higher Amplitude and a steeper increase in the time course curve of the sensor output signal. With the processing of an additional Speed signal can the predetermined rise and amplitude values to the speed of the vehicle or to the relative speed be dynamically adapted from the vehicle to the collision object. In order to will trigger a better adapted triggering of the accident Impact protection achieved and it can be false triggering of the Impact protection system can be prevented.

Further Advantages and applications The present invention will become apparent from the following description in conjunction with the embodiments illustrated in the drawings.

In the description, in the claims, in the abstract and in the drawings are those in the listed below List of reference symbols used terms and associated reference numerals used.

The Drawings show in

1 a first embodiment of a device according to the invention with an impact sensor unit and a processing unit, in which the sensor output signals are provided by acceleration sensors;

2a - 2d in the 1 illustrated device at various forces acting on them F1;

3a - 3c in the 1 illustrated device, wherein collisions take place with different objects; and

4 A second embodiment of the device according to the invention with pressure sensors

1 shows an impact sensor unit 2 and a processing unit 3 for a device for generating a triggering criterion 6 for an impact protection system of a vehicle. The impact sensor unit 2 includes a vehicle skin panel 2.1 , which is preferably designed as a bumper in the front area or as an outer strip of the vehicle, and at least two sensors 2.2 , The sensors 2.2 detect one on the vehicle skin panel 2.1 acting force and each provide a sensor output signal 2.3 , Here are the sensors 2.2 Acceleration sensors. They are with the vehicle skin part 2.1 physically connected. In the simplest case, the acceleration sensors 2.2 in the vehicle skin part 2.1 incorporated in whole or in part.

In the in 1 The apparatus shown are the acceleration sensors 2.2 via a force absorption unit 5.2 , For example, a spring, with the vehicle skin part 2.1 connected. The vehicle skin section 2.1 is designed so that it retains its position at one on the vehicle skin panel 2.1 acting force, for example in a collision, relative to the vehicle chassis 4 changes or deforms. The detection of the deformation or change in position of the vehicle skin part 2.1 is done by measuring the sensor output signals 2.3 the acceleration sensors 2.2 or by measuring the change in the sensor output signals 2.3 the acceleration sensors 2.2 , Instead of the acceleration sensors 2.2 For example, pressure sensors or strain gauges can also be used to detect an acting force.

In addition to the force absorption unit 5.2 includes the in 1 illustrated device a second force absorption unit 5.1 , The two force absorption units 5.1 . 5.2 determine the force-absorbing behavior of the vehicle skin part 2.1 , The two force absorption units 5.1 . 5.2 For example, can be springs with different spring constants. In a collision with a lighter, softer object such as a pedestrian, the spring with the small spring constant becomes effective. In a collision with a heavy, hard object such as a tree or other vehicle first the spring with the small spring constant is effective, then the spring with a large spring constant. This ensures that even a softer object such as a pedestrian a yielding impact zone is provided. The force-absorbing behavior of the vehicle outer skin part 2.1 influences the shape of the waveform of the sensor output signals 2.3 and should therefore be used in the evaluation of the sensor output signals 2.3 be taken into account.

The processing unit 3 is preferably as a microprocessor-controlled device 3.1 trained, in the for the evaluation of the sensor output signals 2.3 required algorithms are implemented as software. The sensor output signals 2.3 become the processing unit 3 each supplied to an input of a microprocessor, which is preferably designed as an A / D converter input. The microprocessor sends a tripping criterion via an interface 6 as a signal to an impact protection system of the vehicle.

2a to 2d show an impact sensor unit 2 and a processing unit 3 with one on the impact sensor unit 2 acting force F1 (in 2a - 2d reference numeral 7 ) depending on the location of the force application. In the following, only the steady state is considered, that is, the mass of the vehicle skin part 2.1 or its damping properties are not taken into account.

In 2a The force F1 acts exactly in the middle between the two via the force absorption units 5.2 with the vehicle skin part 2.1 connected sensors 2.2 , The force F1 is therefore divided into approximately two equal partial forces F (2.2.r), F (2.2.l). Accordingly, two sensor outputs become 2.3 to the processing unit 3 sent to the processing unit 3 are interpreted as partial forces F (2.2.r), F (2.2.l) of about half each of F1.

The force F1 acts directly on one of the two with the vehicle's outer skin 2.1 connected sensors 2.2 as in 2 B shown, determines the processing unit 3 from the two sensor output signals 2.3 a partial force F (2.2.r), which corresponds approximately to the force F1, for the sensor, on which the force acts directly, and a partial force F (2.2.l) of unge ferry 0 for the other sensor.

In 2c the force F1 acts on a point between the two sensors 2.2 , which is about ¼ of the distance between both sensors from the first sensor and about ¾ of the distance between both sensors from the second sensor. According to the law of levers, the force F1 is divided into a partial force F (2.2.r) of about ¾ of the force F1, which is the first sensor output signal 2.3 and in a partial force F (2.2.l) of about ¼ of the force F1 to that of the second sensor output signal 2.3 is detected.

2d shows the case that the force acts in an area outside the distance range between the first and second sensors 2.2 lies. The force acts at a distance outside the range between the first and second sensors 2.2 , which is one fifth of the distance between the first and second sensor 2.2 is the processing unit receives 3 Sensor output signals 2.3 , which correspond to a partial force F (2.2.r) of about 6/5 of the force F1 and a negative partial force F (2.2.l) of about 1/5 of the force F1.

For all four cases of on the vehicle skin part 2.1 acting forces F1, as in 2a to 2d In the simplest case, the amount of the acting force can be determined by adding the partial forces F (2.2.r), F ((2.2.l).

3a to 3c each show a crash sensor unit 2 and a processing unit 3 in a collision with different objects 7.1 . 7.2 . 7.3 , 3a to 3c show the state of the impact sensor unit 2 at the time of the collision. In the processing unit 3 is the respective time profile of the sensor output signals 2.3 graphically displayed starting with the time of the collision.

In 3a The vehicle drives in the middle of a rigid and hard obstacle such as a tree or a pillar 7.1 , The sensor output signals 2.3 have an approximately equal amplitude maximum value, since the distance of the collision point to the first sensor and to the second sensor is the same. The amplitude maximum value is a relatively large value because the collision object is heavy in this case. The sensor output waveforms also show a steep slope because the collision object is a hard object. The time period in which the sensor output signal returns to its initial value shortly before the collision is relatively high.

The situation is different in a collision with a pedestrian 7.2 , as in 3b shown. Again, the maximum amplitude values have the same amount because the vehicle is centered on the pedestrian 7.2 ascended. However, the maximum amplitude values are in comparison to the collision with a tree represented in FIG 3a , much lower because of the pedestrian 7.2 Compared to the tree is a lighter collision object. The increase in sensor output waveforms is less pronounced compared to the collision with a tree shown in FIG 3a because the pedestrian 7.2 represents a softer collision object compared to the tree. In addition, the sensor output signals return faster to their initial value just before the collision than when compared to the tree in FIG 3a because the pedestrian 7.2 as a lighter collision object to the vehicle has a yielding behavior.

In 3c is the collision with a shopping cart 7.3 shown. Again, the maximum amplitude values have the same amount because the vehicle is centered on the shopping cart 7.3 ascended. The amplitude maximum values are similar to those of the collision with the pedestrian in 3b , as well as the shopping cart 7.3 represents a light collision object. Because the shopping cart 7.3 However, in comparison to a pedestrian is a hard collision object, the sensor output waveforms have a similar steep rise as the sensor output waveforms in Fig. A with the tree as a hard obstacle. Because the shopping cart 7.3 much lighter than the vehicle, the sensor output signals return 2.3 faster to their initial value just before the collision back than when compared to the tree in 3a ,

In the processing unit 3 predetermined amplitude values and predetermined slope values are defined. If the measured amplitude value now lies above a first predetermined amplitude value, the collision object is classified as a heavy object. Analogously, the collision object is classified as a light object when the measured amplitude value is below a second predetermined amplitude value. The predetermined amplitude values can be determined eg by comparison test and in the processing unit 3 get saved. Similarly, the measured slope values are given with and in the processing unit 3 stored rise values compared. If the measured slope value is above a first predetermined slope value, the collision object is classified as a hard object. Conversely, the collision object is classified as a soft object if the measured slope value is below a second predetermined slope value. The predetermined amplitude values can also be determined by comparison tests and in the processing unit 3 get saved.

The first predetermined amplitude value may be identical to the second predetermined amplitude value. Then there is a clear classification tion into heavy and light objects. However, if two different amplitude values falling apart are specified, those amplitude values that fall within the range between the first and second predetermined amplitude values can not be unambiguously assigned. These must then either be processed separately in order to use them for the generation of a trigger criterion, or even discarded. Likewise, the first predetermined slope value may be identical to the second predetermined slope value. The classification into hard or soft objects is thus clear. When using two different predetermined slope values, those slope values falling within the range between the first and second predetermined slope values must also be processed separately since they are not unique to the hard or soft objects. It is also conceivable to specify more than two amplitude values or more than two slope values in order to define different mass and hardness ranges. Thus, very light objects such as a ball thrown by children can be distinguished from light objects such as a pedestrian, which in turn can be clearly separated from heavy objects such as a vehicle.

By the classification of the collision object or the determination its mass and hardness properties is a reliable controller the impact protection system possible, in the case of false triggering be avoided on objects other than a pedestrian. So can e.g. between a light and soft pedestrian and a hard, heavy one Vehicle can be distinguished. Likewise it is possible between an impacting Soccer and a pedestrian too different because their masses differ from each other, to prevent the football the impact protection system triggers.

4 Finally, shows an embodiment of the device for generating a triggering criterion for an impact protection system of a motor vehicle, wherein the sensors 2.2 for generating the sensor output signals 2.3 are designed as pressure sensors. The force absorption units 5.1 in this case are pressure chambers whose volume change due to a change in position of the vehicle outer skin part 2.1 through the pressure sensors 2.2 , can be detected. The of the pressure sensors 2.2 generated sensor output signals 2.3 be from the processing unit 3 processed to classify the collision object to the triggering criterion 6 to create.

2

Impact sensor unit

2.1

Vehicle body skin part

2.2

sensor for detecting an on the vehicle skin part

acting force

2.3

Sensor output

3

processing unit

3.1

microprocessor

3.2

A / D converter input of the microprocessor

4

vehicle chassis

5.1

Power absorption unit 1

5.2

Power absorption unit 2

6

interface to an impact protection system

7

on the vehicle applied force F1

F (2.2.r)

identified Partial force of the first sensor

F (2.2.l)

identified Partial force of the second sensor

7.1

Tree / column

7.2

Pedestrians / cyclists

7.3

Shopping venture

Claims (22)

Device for generating a triggering criterion for an impact protection system of a vehicle having an impact sensor unit ( 2 ) comprising a vehicle skin section ( 2.1 ), which maintains its position relative to a vehicle chassis due to a vehicle exterior skin part ( 2.1 ) acting force, and at least two sensors ( 2.2 ), which are provided for detecting a force acting on the vehicle outer skin part force and in each case at least one sensor output signal ( 2.3 ), a processing unit ( 3 ) for evaluating the at least two sensor output signals ( 2.3 ), characterized in that the processing unit ( 3 ) is designed to be based on the time profile of the sensor output signals ( 2.3 ) make a classification of a collision object and dependent thereon a triggering criterion ( 6 ) for the impact protection system. Device according to claim 1, characterized that the classification is a determination of the mass of the collision object includes. Device according to claim 1 or 2, characterized that the classification is a determination of the hardness of the collision object includes. Device according to one of the preceding claims, characterized in that the processing unit ( 3 ) is adapted to be detected at an increase in the waveform of the time course of the sensor output signals ( 2.3 ), whose amount is greater is a first predetermined slope value to classify the collision object as a hard object. Device according to one of the preceding claims, characterized in that the processing unit ( 3 ) is adapted to be detected at an increase in the waveform of the time course of the sensor output signals ( 2.3 ) whose amount is smaller than a second predetermined slope value, classify the collision object as a soft object. Device according to claims 4 and 5, characterized that the first and second predetermined slope values are the same. Device according to one of the preceding claims, characterized in that the processing unit ( 3 ) is configured to be at an amplitude in the waveform of the time course of the sensor output signals ( 2.3 ) whose amount is larger than a first predetermined amplitude value to classify the collision object as a heavy object. Device according to one of the preceding claims, characterized in that the processing unit ( 3 ) is configured to be at an amplitude in the waveform of the time course of the sensor output signals ( 2.3 ) whose amount is smaller than a second predetermined amplitude value to classify the collision object as a light object. Device according to claims 7 and 8, characterized that the first and the second predetermined amplitude value equal are. Device according to one of the preceding claims, characterized in that the processing unit ( 3 ) is adapted to process an additional speed signal of the vehicle or an additional signal of the relative speed from the vehicle to the collision object and to adapt the classification accordingly. Device according to one of the preceding claims, characterized in that one or more of the at least two sensors ( 2.2 ) is a pressure sensor or acceleration sensor. Device according to one of the preceding claims, characterized in that one or more of the at least two sensors ( 2.2 ) is a strain gauge. Method for generating a triggering criterion for an impact protection system of a vehicle, in which an impact sensor unit ( 2 ), which consist of a vehicle outer skin part ( 2.1 ), which maintains its position relative to a vehicle chassis due to a vehicle exterior skin part ( 2.1 ) acting force, and at least two sensors ( 2.2 ), which is used to detect a vehicle skin part ( 2.1 ) are provided, at least two sensor output signals ( 2.3 ) and in which a processing unit ( 3 ) the at least two sensor output signals ( 2.3 ), characterized in that the processing unit ( 3 ) based on the time course of the sensor output signals ( 2.3 ) performs a classification of a collision object and depending thereon a triggering criterion ( 6 ) is generated or influenced for the impact protection system. Method according to claim 13, characterized that the classification is a determination of the mass of the collision object includes. Method according to claim 13 or 14, characterized that the classification is a determination of the hardness of the collision object includes. Method according to one of claims 13 to 15, characterized in that the processing unit ( 3 ) with an increase in the waveform of the time history of the sensor output signals ( 2.3 ) whose amount is larger than a first predetermined slope value, classifies the collision object as a hard object. Method according to one of claims 13 to 16, characterized in that the processing unit ( 3 ) with an increase in the waveform of the time history of the sensor output signals ( 2.3 ), whose amount is smaller than a second predetermined slope value, classifies the collision object as a soft object. Method according to claims 16 and 17, characterized that the first and second predetermined slope values are the same. Method according to one of claims 13 to 18, characterized in that the processing unit ( 3 ) at an amplitude in the waveform of the time history of the sensor output signals ( 2.3 ) whose amount is larger than a first predetermined amplitude value classifying the collision object as a heavy object. Method according to one of claims 13 to 19, characterized in that the processing unit ( 3 ) at an amplitude in the waveform of the time history of the sensor output signals ( 2.3 ) whose amount is smaller than a second predetermined amplitude value, classifies the collision object as a light object. A method according to claim 19 and 20 characterized characterized in that the first and second predetermined amplitude values are the same. Method according to one of claims 13 to 21, characterized in that the processing unit ( 3 ) processes an additional speed signal of the vehicle or an additional signal of the relative speed of the vehicle and collision object and adapts the classification accordingly.