DE102012000789A1 - Method for operating pedestrian protection system for reducing accident severity during front collision with pedestrian in motor vehicle, involves evaluating measuring data of detection devices by safety systems - Google Patents

Abstract

The method involves evaluating the measuring data of the detection devices (8,9) by safety systems (10,11) depending on an actuation condition. The actuation condition has a platform break through criteria evaluated depending on measuring data of a three-dimensional optical detection device, where it is tested whether a collision object breaks through a vertical place cutting an engine hood (4) of the motor vehicle along a line that has a predetermined distance to the front end of a motor vehicle (1). Measuring data of two detection devices, particularly the optical detection device and a collision sensor (13), are evaluated in line with the actuation condition. An independent claim is included for a motor vehicle with an optical detection element.

Description

The invention relates to a method for operating a pedestrian protection system for reducing the accident severity during head-on collisions with pedestrians in a motor vehicle, wherein at least one safety system is triggered as a function of at least one triggering condition evaluating the measurement data of at least one detection device. In addition, the invention relates to a motor vehicle with a pedestrian protection system.

For the protection of pedestrians in a frontal accident with motor vehicles, various measures implemented by safety systems are proposed today, in particular passive measures. Pedestrian protection systems are known in which one or more collision sensors (contact sensors) in the frontal area (front end) of the motor vehicle are installed as detection devices. These collision sensors usually detect a collision of a pedestrian or any object. A corresponding algorithm evaluates various features of the measured data (sensor signals) and decides on the basis of a triggering condition, which may also include various nested criteria, whether a safety system should be triggered in particular as a passive measure.

As a possible security system, for example, the DE 10 2005 012 136 A1 a pedestrian airbag system which describes an external airbag to be inflated in the area of the windshield. The pedestrian airbag system can be mounted on the rear edge of the hood of a motor vehicle and can be triggered by a trigger condition accordingly. Also DE 100 13 563 A1 and DE 10 2007 029 987 B4 disclose such external windshield airbags that lie over the windshield of a motor vehicle to attenuate the impact of a pedestrian there can. These publications also show a second known safety system for pedestrian protection, namely a engagable hood of the motor vehicle, which is opened to protect the pedestrian by a certain angle. DE 10 2005 012 357 A1 describes as a further safety system a height adjustment unit which, while a lifting unit lifts an engine hood of the motor vehicle, lowers the motor vehicle so that the pedestrian is steered onto the hood and protected by a windshield outer airbag.

The problem here is that the sensors can not issue a safe classification with respect to a real pedestrian and the algorithms are designed to trigger a Ersatzimpaktors so that the above measures or safety systems can also be triggered by mistake when the entry of an object in the front end of the motor vehicle is similar to that of a pedestrian or a Ersatzimpaktors. Even optical detection devices, in particular optical sensors, usually can not identify with sufficient certainty the class "pedestrian", so that it can lead to false triggering.

Although in reversible measures, ie safety systems in which the actuators are also designed to defer the triggered safety system, false releases are still acceptable because they can be easily reset by the driver or a corresponding workshop, for example in the case of resettable crash-active hood. However, a falsely triggered safety system, especially an outside airbag, will probably be faulted by the driver. In addition, there is a problem with a wrong triggered external airbag on the windshield that the driver's view can be obscured.

False triggering by flying plastic bags, birds, branches and the like may occur, for example, in the evaluation of optical measurement data, with a contact sensor or collision sensor in the front end a false triggering of small animals, game, flying plastic bags, mullions, beacons, balls and the like can.

To reduce the risk of false triggering was through DE 10 2005 006 763 A1 proposed to provide a first non-contact sensor device and a second sensor device detecting a force of an object upon impact with the motor vehicle. Thus, two independent sensors should each confirm an event to avoid false triggering. Specifically, there, it is proposed to estimate a mass-indicative and / or a hardness-indicative size of the first object based on the force and the relative velocity and to recognize the object as a specific object type when the estimated mass-indicative and / or hardness-indicative Size is within a specified range. However, an extremely complex evaluation algorithm is necessary, which itself is again susceptible to errors and has to complexly connect a large number of features of the measurement data, in particular also with regard to criteria of the triggering condition.

The invention is therefore based on the object to provide a method for operating a pedestrian protection system, in which in a simple way, in particular the plausibility Serving, reliable further criterion within the trigger condition can be realized.

To solve this problem, it is provided according to the invention in a method of the type mentioned that the trigger condition comprises a level breakdown criterion evaluated as a function of measured data of a three-dimensional optical detection device, wherein it is checked whether a collision object is a motor vehicle hood along a predetermined distance to the front End of the motor vehicle having line intersecting vertical plane breaks through.

According to the invention, it is therefore proposed that a three-dimensional optical detection device, in particular an optical sensor, provides measurement data so that a plane breakdown criterion can be evaluated, which ultimately describes a type of "virtual curtain". This is based on the finding that the use of some security systems only just makes sense if the collision object, in particular the pedestrian, also moves on the hood towards the windshield, which is often referred to as "folding over". This is especially true for security systems that work in the area of the windshield, such as a windshield exterior airbag.

Thus, as a virtual curtain, a vertical plane is defined in the space relative to the installation location of the three-dimensional optical detection device, the penetration of which can be easily checked due to the three-dimensionality of the data. The exact position of the vertical plane should be chosen so that false triggering, for example by partially overlapping, but then zurückschnellende beacons and the like, as possible avoided, on the other hand so that taking into account the data rate of the optical detection device and the remaining latencies, the security system in good time is triggered to maintain its impact-mitigating effect. For example, it may be found that the sensing time of the optical detector should be in the range of 5 to 30 ms. In addition, it is advantageous if the optical detection device is designed so that successively measured measurement data of the optical detection device are plausibilized against each other, that is, the detection rate is chosen so that not only on a single, a breakthrough of the vertical plane indicative value, the Measurement error could be, is already responding, but successive measurement data must show the breakthrough. Here, depending on the specific embodiment of the motor vehicle, a detection rate of the optical detection device in the range of 150 or more Hz, in particular 200 Hz, may be preferred.

Consequently, it can be provided with particular advantage that a PMD camera is used as the optical detection device. Such detection devices are often referred to as TOF (time-of-flight) cameras and are available at such high acquisition rates. In addition to the usual, pixel-by-pixel optical information, PMD cameras also provide distance information for each of their pixels, which can be evaluated with regard to the "virtual curtain". It should be noted, however, that other, fast optical detection devices can be used without problems.

The level breakdown criterion presented here represents an extremely safe variant of controlling the triggering of collision objects, in particular of course pedestrians, of meaningful security systems, especially when the motor windscreen is folded over and moved against the windscreen, whereby it is particularly suitable for plausibility checking.

Consequently, the method according to the invention can be improved particularly advantageously by evaluating measurement data from at least two detection devices based on different principles, in particular the optical detection device and at least one collision sensor responsive to contact with a collision object, within the context of the triggering condition. In this case, the level breakdown criterion ultimately serves to validate a pedestrian accident, since in addition to the optical detection device there is at least one further detection device based on a different measurement principle whose measurement data are also taken into account in the at least one triggering condition. The further detection device is expediently the collision sensors which are already frequently provided today and which can measure a contact of an object with the motor vehicle in various ways. In a concrete realization example, acceleration sensors can be provided on the bumper of the motor vehicle and / or contact sensors such as optical fibers, force-sensitive sensors and the like can be used. Various, basically known from the prior art possibilities are conceivable.

In a particularly expedient embodiment of the present invention, it may be provided in this context that upon detection of a frontal collision by means of the further detection device, at least one safety system is triggered only when the level breakdown criterion is met. Thus, there is a plausibility check, in particular with regard to security systems acting in the area of the windshield. If, for example, a motor vehicle in a specific embodiment comprises an adjustable hood and a windshield outer airbag as safety systems, the hood can first be turned on when a collision is detected via collision sensors. In addition to the collision detected by the collision sensors, however, within the framework of the triggering condition for the outer airbag, the plane break-through criterion must inevitably additionally be fulfilled (in time correlation) so that the outer airbag is inflated.

Of course, other types of use of the layer breakdown criterion within the trigger conditions are also conceivable, so that, for example, upon fulfillment of the layer breakdown criterion, at least one threshold value of a criterion relating to the measurement data of the further detection device is adapted to the triggering of the safety system. In this refinement, the level breakdown criterion is therefore used for further plausibility checking in that threshold values which in particular determine the triggering of the security system as a function of the measurement data of the further detection device are adjusted.

In addition to the adaptation of threshold values of further criteria and the AND operation also described above with a criterion relating to the measurement data of the further detection device, an evaluation of the measurement data of the optical detection device and the further detection device can be carried out to a common collision value, which then implicitly violates a plane breakdown criterion comprehensive criterion is evaluated and the like.

In a further embodiment of the present invention can be provided that the predetermined distance as a maximum Überklapplänge a Leitbake on the hood ( 4 ) of the motor vehicle ( 1 ), if necessary with the addition of a safety tolerance length. Such an estimate of the location of the "virtual curtain" has proved to be particularly useful, in particular to exclude objects that overwhelm the hood, but then snap back. In this way, problematic objects such as beacons, posts and objects, which are smaller than the hood, can often be excluded as a cause for triggering.

In a further embodiment of the present invention can be provided that the optical detection device is arranged in the region of a windshield of the motor vehicle, in particular at the upper edge of the windshield and / or in the interior of the motor vehicle. For example, it may be provided to provide the optical detection device directed in the direction of travel of the motor vehicle in a rearview mirror or rearview mirror mount, but other, in particular central installation locations on the upper edge of the windshield are conceivable. However, other locations in the windscreen are possible, for example, on the A-pillars, in the exterior mirrors and the like. In principle, an obstruction on the hood is conceivable, for example, windshield side, while generally a shoring in the front of the vehicle should be avoided, since the vertical plane can not otherwise be detected meaningful. It should be pointed out at this point that the detection range of the three-dimensional optical detection device essentially results from the extent of the section of the vertical plane to be monitored, ie the actual "virtual curtain", it also being possible to use a suitable optical system Collision objects, which occur rather on the lateral edge of the hood above this to detect. Ideally, the detection range is chosen so that anyway no laterally adjacent to the hood the vertical plane through the objects are detected, which is otherwise excluded in the general case by a corresponding algorithm, which means that criterion includes checking whether the vertical plane breaking object located above the hood of the motor vehicle.

In the context of the present invention, it can also be provided that the measurement data of the optical detection device are used further, also within the framework of the pedestrian protection system. Thus, it is possible, for example, to consider further, in particular plausibilizing criteria relating to the measurement data of the optical detection device in triggering conditions. It has proved to be particularly advantageous if the and / or a further triggering condition comprises, as an additional criterion, a height criterion evaluating the exceeding of a height threshold by at least one height of a collision object determined from the measurement data of the optical detection device. In this way, the amount of a collision object, which can be easily determined on the basis of the three-dimensional information of the measurement data of the optical detection device, can also be taken into account, in particular already with foresight. Such a height criterion can be used particularly advantageously to adapt threshold values of further criteria, in particular those related to measurement data of the further detection device, and thus by a Threshold adjustment to plausibiliseren. Thus, for example, a safety system can be triggered more easily, that is to say the triggering threshold can be lowered if it has been determined that the collision object is smaller than the bonnet, so that, for example, the altitude threshold is selected to be the height of an excellent point of the motor vehicle's bonnet above the ground can, in particular a front end of the hood.

In a further advantageous embodiment of the present invention, it can be provided that a collision object type is also determined from the measured data of the optical detection device and used to adapt at least one criterion of the triggering condition. In this refinement, the measurement data of the optical detection device are therefore also evaluated further beyond the virtual curtain and possibly the height of objects, for example in order to allow a classification of possible or actual collision objects and thus to create a further plausibility level, for example by checking whether a collision object is a pedestrian. Of course, such an estimation can already take place well before the actual occurrence of the collision, for example by constantly monitoring the apron of the motor vehicle.

It is therefore also possible to derive warning notices and the like from the data of the optical detection device, which of course can also provide its measured data to other vehicle systems of the motor vehicle which can evaluate them, for example to driver assistance systems relating to the longitudinal or lateral guidance and the like. If, as has been described, a collision object type is determined, this can also be used to adapt at least one criterion of the triggering condition, for example by adjusting threshold values, in particular also the altitude threshold, depending on the collision object type and the like.

As a safety system, as already mentioned, at least one adjustable hood and / or a windscreen outer airbag can be triggered as a function of or in each case one triggering condition. These examples of safety systems have already been described in detail in the introduction. While it makes sense in relation to the height criterion both in a engagable hood and in a windshield outer airbag to consider this in the respective trigger conditions or a common trigger condition, especially after the height criterion is particularly suitable for estimating the height threshold value as described suitable whether a collision object is ever moved on to the hood or windshield of the motor vehicle, the consideration of the level breakdown criterion is particularly suitable for consideration in the triggering of the windshield outer airbag.

In addition to the method, the present invention also relates to a motor vehicle, comprising an optical detection device, at least one safety system and a pedestrian protection system for accident severity in frontal collisions with pedestrians, which comprises a control device designed for carrying out the method according to the invention. For communication between the optical detection device and optionally further detection devices and the control device, for example, a conventional bus system of a motor vehicle, such as a CAN bus, may be provided. All statements relating to the method according to the invention can be analogously transferred to the motor vehicle according to the invention, with which therefore the same advantages can be achieved.

Further advantages and details of the present invention will become apparent from the embodiments described below and with reference to the drawing. Showing:

1 a schematic diagram of a motor vehicle according to the invention,

2 a view of the hood of the motor vehicle,

3 a sketch for determining the distance of the vertical plane from the front end of the motor vehicle,

4 a first schematic side view of the motor vehicle according to the invention with respect to the virtual curtain

5 a second schematic side view of the motor vehicle according to the invention with respect to the object height and

6 a flowchart of an embodiment of the method according to the invention.

1 shows a schematic diagram of a motor vehicle according to the invention 1 , More precisely, the front part of a motor vehicle according to the invention 1 , This has a bumper 2 at his frontend 3 on. To the frontend 3 closes, as basically known a bonnet 4 which is essentially up to a windshield 5 enough.

In order to reduce head collisions with a pedestrian as possible in their severity, the motor vehicle has 1 a pedestrian protection system 6 with a control unit 7 on, the measurement data of various detection devices 8th . 9 evaluates safety systems to meet a triggering condition 10 . 11 of the motor vehicle 1 here triggering each of the security systems 10 . 11 a separate trigger condition is assigned.

As a three-dimensional optical detection device 8th is a PMD camera in the present embodiment 12 intended. As another detection device 9 , which is based on a different measuring principle, are in the area of the bumper 2 different collision sensors 13 arranged, which provide corresponding measurement data on contact with a collision object.

As security systems 10 . 11 In the present case, on the one hand, there is an adjustable bonnet 4 with corresponding actuators 14 and a windshield exterior airbag 15 intended. When the safety system is triggered 10 becomes the hood 4 as by the position 4 ' indicated employed, when triggering the security system 11 becomes the outside airbag 15 to the form 15 ' so inflated that the windshield 5 is covered by him. Thus, a pedestrian is over the hood 4 continue towards the windscreen 5 is moved by the hired hood 4 and the outside airbag 15 ' intercepted, so that the consequences of accidents are reduced.

The control unit 7 is now adapted to carry out the method according to the invention, that is, it is by the control unit 7 the data of the PMD camera 12 evaluated such that one is checked in the context of a level breakdown criterion, whether the hood 4 Vertical plane crossing a line through the collision object above the hood 4 is broken. The vertical plane thus acts as a kind of "virtual curtain".

2 shows a view of the hood 4 and the front portion of the motor vehicle 1 , where the course of the vertical plane based on the line 16 making the cut with the hood 4 is clearly visible. Shown is also the detection range described by an angle α 17 the at the top of the windshield 5 inside the motor vehicle 1 , in particular on a rearview mirror or a rearview mirror mount, arranged PMD camera 12 which can be seen to capture the vertical plane in its entire relevant width. Events next to the hood 4 , compare dashed lines 18 , are filtered out if they are even within the detection range. After the PMD camera 12 Also provides a depth information, so a distance information, for each pixel, an opening of the vertical plane can be easily determined.

As can be seen, the vertical plane is a distance d, reference numeral 19 , from the front end of the motor vehicle 1 spaced. The distance 19 is chosen so that an overflowing standard Leitbake 20 the vertical plane no longer penetrates, as through the schematic diagram of the 3 should be shown in more detail.

The Leitbake works well, too 20 a piece over the hood 4 before you, arrow 21 , back down again. The distance 19 is now chosen so that a standard beacon 20 in no case the here also in the vertical direction apparent vertical plane 22 permeates and yet still, considering processing and latency, after a detected penetration of the vertical plane 22 the outside airbag 15 can be triggered on time. In the present case, the PMD camera points 12 a detection rate of 200 Hz, so that even two temporally consecutive events can be evaluated to exclude measurement errors in individual pixels. It should also be noted at this point that the level breakdown criterion, after a pedestrian has a certain extent, also the penetration of the vertical plane 22 in several places, so pixels, as a review may include.

4 shows for a more detailed explanation now, as in a frontal collision with a pedestrian 23 this on the hood 4 flips over and thus the vertical plane 22 penetrates as a virtual curtain.

In addition, in the present exemplary embodiment, a height criterion based on measured data of the optical detection device is additionally used in the context of the overall control 8th evaluated and in the context of at least the triggering condition for the engagable bonnet 4 takes into account, due to the yes also the distance information containing measurement data determines a height of a collision object and compared with a height threshold.

Exactly here is the sketch of the principle 5 to see which the motor vehicle 1 on a street 24 driving shows. The situation is close to collision with a pedestrian 23 shown. The pedestrian 23 is visible in the detection area 17 the PMD camera 12 , Now that also provides distance information and the overall geometry and position of the PMD camera 12 are known, the height can 25 of the pedestrian 23 as a collision object 26 from the measured data of the PMD camera 12 be determined. When Height threshold for meeting the height criterion is the height 27 the front edge of the hood 4 provided, that means it will check if the collision object 26 the hood 4 surmounted.

The PMD camera 12 It is arranged in an excellent position after being at the top of the windscreen 5 inside the motor vehicle 1 located. Only in the actual collision then speak the collision sensors 13 at.

6 now shows how, in one embodiment of the method according to the invention, the level breakdown criterion and the height criterion can be taken into account within the triggering conditions. It should be noted at this point that in the illustrated embodiment of the method according to the invention, the measurement data of the PMD camera 12 anyway to be evaluated constantly in order to advance the motor vehicle 1 To be able to classify located objects, so that the basic classification of a collision object 26 as a pedestrian 23 already has an influence on threshold values taken into account in the context of the triggering conditions.

The measured data 28 the PMD camera 12 be first on the basis of the height criterion 29 evaluated. Is this fulfilled, arrow 30 , Thresholds become one of the measured data 31 the collision sensors 13 evaluative criterion 32 adjusted so that a trigger, step 33 , the security system 10 , so the adjustable hood 4 It is more likely, that is, the threshold for a release of the security system 10 is lowered. The height criterion 29 serves therefore to plausibilizing adaptation of the criterion 32 ,

Only if a collision has been detected, hence the bonnet 4 was hired (step 27 ), the measurement data become 28 the PMD camera 12 further evaluated to within the scope of the layer breakdown criterion 34 to determine if the collision object 26 is folded over and the vertical plane 22 , the virtual curtain, penetrates, as already explained in more detail above. If necessary, an adaptation based on the altitude criterion can already be made here as well 29 or a classification has been made so that, for example, a larger or smaller number of pixels is sufficient to the criterion 34 when a collision-time-related breakthrough occurs.

So in the end, that's the criterion 32 and the level breakdown criterion 34 here AND-linked to in one step 35 if the overall triggering condition is fulfilled, the safety system as well 11 to trigger the outside airbag.

There are also other links of criteria 29 . 32 . 34 within the various, optionally, as here, partially overlapping trigger conditions conceivable.

Overall, the inventive method makes it possible to significantly reduce false triggering by objects such as beacons, flying plastic bags, birds and the like.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102005012136 A1 [0003]
• DE 10013563 A1 [0003]
• DE 102007029987 B4 [0003]
• DE 102005012357 A1 [0003]
• DE 102005006763 A1 [0007]

Claims (10)

Method for operating a pedestrian protection system ( 6 ) to reduce the accident severity in frontal collisions with pedestrians ( 23 ) in a motor vehicle ( 1 ), whereby at least one security system ( 10 . 11 ) as a function of at least one triggering condition, the measured data ( 28 . 31 ) at least one detection device ( 8th . 9 ), is triggered, characterized in that the triggering condition depends on measured data ( 28 ) of a three-dimensional optical detection device ( 8th ) evaluated level breakdown criterion ( 34 ), in which it is checked whether a collision object ( 26 ) one the hood ( 4 ) of the motor vehicle ( 1 ) along a predetermined distance ( 19 ) to the front end of the motor vehicle ( 1 ) line ( 16 ) intersecting vertical plane ( 22 ) breaks through. A method according to claim 1, characterized in that in the context of the trigger condition measurement data ( 28 . 31 ) of at least two detection devices based on different principles ( 8th . 9 ), in particular the optical detection device ( 8th ) and at least one upon contact with a collision object ( 26 ) responsive collision sensor ( 13 ), be evaluated. Method according to Claim 2, characterized in that upon detection of a frontal collision by means of the further detection device ( 9 ) at least one security system ( 10 . 11 ) only if the level breakdown criterion ( 34 ) is triggered. Method according to one of the preceding claims, characterized in that the predetermined distance ( 19 ) as a maximum overlap length of a beacon ( 20 ) over the hood ( 4 ) of the motor vehicle ( 1 ), if necessary with the addition of a safety tolerance length. Method according to one of the preceding claims, characterized in that as an optical detection device ( 8th ) a PMD camera ( 12 ) is used. Method according to one of the preceding claims, characterized in that the optical detection device ( 8th ) in the area of a windscreen ( 5 ) of the motor vehicle ( 1 ) is arranged, in particular at the upper edge of the windshield ( 5 ) and / or inside the motor vehicle ( 1 ). Method according to one of the preceding claims, characterized in that the and / or a further trigger condition as an additional criterion, the exceeding of a height threshold by at least one of the measured data ( 28 ) of the optical detection device ( 8th ) certain height ( 25 ) of a collision object ( 26 ) evaluating height criterion ( 29 ). Method according to one of the preceding claims, characterized in that from the measured data ( 28 ) of the optical detection device ( 8th ) also determines a collision object type and to adapt at least one criterion ( 29 . 32 . 34 ) of the triggering condition is used. Method according to one of the preceding claims, characterized in that as security system ( 10 . 11 ) at least one engagable hood ( 4 ) and / or a windshield outer airbag ( 15 ) depending on the layer breakdown criterion ( 34 ) trigger condition. Motor vehicle ( 1 ), comprising an optical detection device ( 8th ), at least one security system ( 10 . 11 ) and a pedestrian protection system ( 6 ) to reduce the accident severity in frontal collisions with pedestrians ( 23 ) with a control device designed for carrying out a method according to one of the preceding claims ( 7 ).

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