DE102015011928A1 - Method for operating a safety system of a motor vehicle and motor vehicle - Google Patents

Abstract

Method for operating a safety system of a motor vehicle (1), which safety system (16) evaluates sensor data of at least one environmental sensor of the motor vehicle (1) for determining at least one collision parameter describing a possible collision with a collision partner and at least one of the warning of the driver in at least one met criterion and / or the collision avoidance and / or Kollisionsfolgenminderung serving, the measures criterion associated measure performs, being used as at least one environmental sensor at least one radar transceiver (12) realizing semiconductor chip (10) having radar sensor (2), wherein from radar data of at least one in at least part of its detection range, the radar sensor (2) detecting the subsurface (20) driven by the motor vehicle (1) has a height value (18, 18 ') of the radar sensor (2) above the ground (20) and from all detected altitude values a Bel adungszustandsinformation the motor vehicle (1) is determined, which is taken into account in the determination of the at least one collision parameter.

Description

The invention relates to a method for operating a safety system of a motor vehicle, which safety system evaluates sensor data of at least one environmental sensor of the motor vehicle for determining at least one collision parameter describing a possible collision with a collision partner and at least one of the warning of the driver and / or the collision avoidance in at least one satisfied action criterion and / or Kollisionsfolgenminderung serving measures associated with the measure measures performed, being used as at least one environmental sensor at least one radar transceiver a realizing semiconductor chip exhibiting radar sensor. In addition, the invention relates to a motor vehicle.

Modern motor vehicles often have a multiplicity of driver assistance systems that use environmental sensors of the motor vehicle in order to detect the static and dynamic environment of the motor vehicle. A special type of such driver assistance systems are the safety systems that support or warn the driver in critical traffic situations. In order to assess the criticality of the current driving situation, in addition to the sensor data of the environmental sensors, ego data describing the operating state of the own motor vehicle are also usually used, for example the current speed of the motor vehicle and the like. The result of the criticality evaluation of the current driving situation are in particular collision parameters which describe a possible collision, for example times until collision with objects detected in the surroundings of the motor vehicle, collision probabilities and the like. With regard to the interpretation of the criticality of the current driving situation, however, there are further possibilities for improvement. A parameter that is currently not taken into account is the loading state of the motor vehicle. On the one hand, the state of loading can impair the performance of the environmental sensors; on the other hand, the calculation of the braking distances or taking into account the load state of the own motor vehicle can cause the measure, in particular a warning, to be carried out later.

The invention is therefore based on the object of specifying a way to take into account the loading state of the motor vehicle in the determination of collision parameters by a security system.

To achieve this object, the invention provides, in a method of the type mentioned above, that radar data of the at least one radar sensor detecting in at least part of its detection range a radar sensor height value above the ground and all detected altitude values a load status information of the motor vehicle is determined, which is taken into account in the determination of the at least one collision parameter.

According to the invention, it is therefore proposed to estimate the loading state of the motor vehicle based on semiconductor technology based radar sensors. For example, if the distance between the radar sensor on the rear bumper and the ground, which is traveled by the motor vehicle, very greatly reduced, it can be assumed that the motor vehicle is heavily laden. Due to the tilting of the body, the front radar sensors also measure an increased distance to the ground. The present invention utilizes the fact that the newly disclosed radar sensors, which are based on semiconductor technology, in particular CMOS technology, provide high-resolution radar data, which also make it possible to measure structures of the ground and thus the distance to it, from which Especially when viewing reflections at different angles, a height value can be determined that indicates the height of the radar sensor above the ground in a particularly reliable manner.

The realization of semiconductor-based radar components has long proved difficult, as expensive specialty semiconductors, particularly GaAs, have been required. Smaller radar sensors have been proposed, whose entire radar frontend is realized on a single chip in SiGe technology before solutions in CMOS technology became known. Such solutions are the result of extending CMOS technology to high frequency applications, often referred to as RF CMOS. Such a CMOS radar chip is realized extremely compact and does not use expensive special semiconductors, thus offers significant advantages over other semiconductor technologies, especially in the production. An exemplary implementation of a 77 GHz radar transceiver as a CMOS chip is described in the article by Jri Lee et al., "A Fully Integrated 77GHz FMCW Radar Transceiver in 65nm CMOS Technology", IEEE Journal of Solid State Circuits 45 (2010), pp. 2746-2755 , described.

After it has also been proposed to realize the chip and the antenna in a common package, a very low cost small radar sensor is possible, which can meet the space requirements significantly better and due to the short signal paths also has a very low signal-to-noise ratio and for high frequencies and larger, variable frequency bandwidths suitable is. Therefore, such small-sized radar sensors can also be used for short-range applications, for example in the range of 30 cm to 10 m.

It has also been proposed to provide such a CMOS transceiver chip and / or a package with CMOS transceiver chip and antenna on a common circuit board with a digital signal processing processor (DSP processor) or the functions of the signal processing processor in the CMOS Integrate transceiver chip. Similar integration is possible for control functions.

A preferred embodiment of the present invention therefore provides that a control unit and / or a digital signal processing component of the radar sensor is realized by the semiconductor chip and / or the semiconductor chip and an antenna arrangement of the radar sensor are realized as a package. In this way, the radar sensor can be realized even more compact and kleinbauender, which simplifies the concealed installation of the radar sensor in the motor vehicle, but on the other hand, the detection quality significantly increased after signal paths are further shortened, the signal-to-noise ratio significantly increased and operating modes are enabled in which improved resolutions are given, for example by increasing the frequency bandwidth. It is also extremely expedient that the antenna arrangement of the radar sensor is designed to improve reflection angles in two mutually perpendicular planes, so that therefore angles in azimuth and elevation can be measured. The elevation angles give a clear indication of which angle belongs to a measured distance to the road, hence a reflection received from there.

A particularly expedient development of the invention provides that the radar sensor is operated with a frequency bandwidth greater than 1 GHz, in particular of 4 GHz, and / or in a frequency range of 77 to 81 GHz. High frequency bandwidths increase the distance separating capability, so that it is possible, in particular, to dissolve individual structures of the subsoil in the vicinity and to assign them to them, so that the subsoil can therefore be reliably measured.

Overall, therefore, radar sensors are used, which detect high-precision radar data through their particular given by the CMOS technology high integration of all radar components on a chip. A high frequency bandwidth supports the ability to detect differences in altitude of the radar sensor relative to the ground very accurately, especially when using a bandwidth of 4 GHz. Small height changes of the body relative to the ground, which are triggered by a change in loading, can be detected with high precision.

With particular advantage, the method according to the invention provides that a plurality of, in particular three, radar sensors directed to the apron and behind the motor vehicle are used. In particular, an embodiment can be selected in which the radar sensors cover the surroundings of the motor vehicle in a 360 ° angle range. In this case, for example, eight radar sensors can be used, of which three are installed in the rear bumper, three in the front bumper and two laterally, for example, in doors of the motor vehicle preferably concealed. The use of a plurality of radar sensors has the advantage that in particular in all areas of the motor vehicle, the height variation can be measured, so that not only a plausibility of the individual measurements can take place against each other, but also a much more accurate picture of the load of the motor vehicle can be drawn Consequently, the loading state information can in particular also detect states in which a load is given to one side.

Specifically, it can be provided that the loading state information is determined as a function of a height value measured in advance of the motor vehicle and measured at the rear of the motor vehicle. As already mentioned, this variant can be regarded as being plausible, since with a tilting of the body due to the load, a low height value at the rear results in an increased height value at the front of the motor vehicle. In this case or also generally it is particularly expedient if height values measured by a plurality of radar sensors at the rear and / or at the front of the motor vehicle are statistically combined with one another and / or used for mutual plausibility. If, for example, three radar sensors are installed at the rear of the motor vehicle in the rear bumper, each of these radar sensors delivers an altitude value, wherein the radar sensors are usually arranged at least substantially at the same position along the vehicle longitudinal axis. Since the load usually leads to a mutually substantially symmetrical change in the height value, the height values of the radar sensors can be compared for plausibility and / or statistically combined to increase the accuracy of measurement. In particular, it is conceivable, at least in more than two radar sensors at the rear or at the front of the motor vehicle, to precede a Ausreißerdetektion, with a further plausibility in the context of the present invention also over the time course of a single height value of a radar sensor can be made. In particular, it is expedient here, for example, to form a moving average with upstream outlier detection.

In order to determine the loading state information, it may be provided that a load state information is assigned to the at least one measured height value by means of a characteristic field or a look-up table. In this context, it can be provided with particular advantage that a calibration measurement is carried out at different loading states of the motor vehicle in order to determine the characteristic map or the look-up table. It can therefore be carried out in the run-up to the use of the method, a series of measurements to generate an association between changes in the height of the radar sensor above the ground and the loading state of the motor vehicle. The corresponding results can be stored in the form of a look-up table in a controller executing the method, and / or a characteristic curve or a characteristic curve can be used with only one measured height value.

When ascertaining the altitude value, it is also possible to take into account noise components and / or misdetections originating from the subsoil, in particular by multiple reflection. In particular, a change in the height of the radar sensor to the ground manifests itself in the overall structure of the radar data, so their overall characteristics. For example, if the altitude value decreases, stronger reflections are produced from the ground, resulting in increased noise due to the so-called "ground clutter". In addition, more ghost targets occur due to multiple reflections across the soil surface. If these characteristics can be quantified by suitable algorithms, one obtains a further indication of the change in the altitude value or, if corresponding associations exist, even of its value, so that the effects can be used to assist in the determination of the altitude value.

With particular advantage, however, the evaluation of the radar data itself can be adjusted as a function of the loading state information. If the change in the altitude value is known, then it is also known that an altered characteristic of the radar data compared to the "normal altitude" is to be expected. Thus, for example, due to a higher "bottom clutter" due to the lowering of the altitude value, an increase of detection thresholds can take place. Moreover, algorithms for detecting "ghost targets" formed by multiple reflection can be activated and / or more sensitively parameterized. Consequently, the evaluation by adapting certain evaluation parameters can be specifically adapted to the changed circumstances due to the loading state of the motor vehicle in order to avoid false and / or false warnings due to incorrect detection.

A concrete embodiment of the invention provides that at least one plausibility criterion is used to exclude a height value that is erroneously changed due to misadjustment of the radar sensor. This is preferably a specific configuration of the mutual plausibility of the altitude values of different radar sensors. If one of these radar sensors is misaligned, for example due to a change in the installation position, its height values will not appear to match the measurements of the other radar sensors. It can therefore be determined that the changed altitude is due to a misalignment of the radar sensor, so that the corresponding change is disregarded. Of course, it is advantageous and preferred according to the invention to use the resulting misalignment information otherwise, for example for the correction of future height values measured by the radar sensor in order to compensate for the errors occurring due to the misalignment. Of course, such a detected maladjustment information can also be used to adjust the evaluation of the radar data and its fundamental software calibration in order to achieve a fundamental correction in any evaluation. A maladjustment information indicating an excessive misalignment may be used to inform the driver. In this sense, the determination according to the invention of the loading state information is supplied to a further purpose, namely in particular the detection of a misalignment of a radar sensor by plausibility checking with regard to the other radar sensors. However, it should be noted at this point that in principle it is also conceivable to monitor the radar data of a single radar sensor for a maladjustment, in particular if the sensor is installed concealed. If the radar sensor then also delivers reflections from a component to be transmitted through it, the corresponding reflection patterns can provide indications as to whether the installation position of the radar sensor has changed, thus providing the maladjustment information which is used to exclude certain changes or specifically for the correction of the height values (and Other radar data) of the radar sensor can be used.

Once the loading status information has been determined, parameters of various algorithms of the security system can subsequently be adapted, for example. For example, it may be provided that the loading state in the calculation of the braking distances, the collision probabilities and / or or times to collision (TTC - time to collision). In this way a reliable operation of the security system with timely measures is made possible.

In addition to the method, the invention also relates to a motor vehicle, comprising a safety system that evaluates sensor data of at least one environmental sensor of the motor vehicle for determining at least one collision parameter describing a possible collision with a collision partner and at least one of the driver's warning and / or the at least one met criterion Collision avoidance and / or Kollisionsfolgenminderung serving, the measure measures assigned performs, being provided as at least one environmental sensor, a radar transceiver realizing semiconductor chip exhibiting radar sensor, wherein the safety system has a designed for performing the method according to the invention control unit. All statements relating to the method according to the invention can be analogously applied to the motor vehicle according to the invention, so that the advantages already mentioned can also be achieved with them.

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

1 a motor vehicle according to the invention,

2 a radar sensor of the motor vehicle,

3 a sketch for changing the height of a radar sensor when loading the motor vehicle, and

4 a sketch of the characteristics of the radar data at a changed altitude.

1 shows a schematic diagram of a motor vehicle according to the invention 1 , The car 1 Points to the environment of the motor vehicle 1 directed, semiconductor-based radar sensors 2 which are presently designed as wide-angle radar sensors and detection areas 3 have a 360 ° angle interval around the motor vehicle 1 cover and partially overlap. The small-sized radar sensors 2 are concealed, with the front three radar sensors 2 in a front bumper 4 , the rear three radar sensors 2 in a rear bumper 5 and the side radar sensors 2 in doors 6 of the motor vehicle 1 behind a painted, installed in the door panel radar-permeable windows are installed.

2 shows the structure of the radar sensors 2 more accurate. Every radar sensor 2 has a housing 7 in which a circuit board is mounted, which is a package 9 carried by a realized here as a CMOS chip semiconductor chip 10 and an antenna arrangement 11 is formed. Through the semiconductor chip 10 be next to the radar transceiver 12 also a control unit 13 and a digital signal processing component 14 (DSP) realized. The antenna arrangement 11 is designed to allow angular resolution in two mutually perpendicular planes, here azimuth and elevation. For a particularly high distance separating capability, the radar sensors 2 operated with a high frequency bandwidth, in particular up to 4 GHz, in a frequency range of 77 to 81 GHz.

Radar data of radar sensors 2 Therefore, they are also suitable for identifying reflections of the background as such and for resolving individual reflection centers. For example, if the road is asphalted, there is a certain surface structure that results in a particular pattern of reflection centers due to the high-precision radar data of the radar sensors 2 can be identified. Can, however, reflection centers than that of the motor vehicle 1 be identified belonging to the subsurface and are the angles and the distances of these reflection centers to the radar sensor 2 is known, especially when considering several such reflection centers, in a simple manner to the height of the radar sensor 2 above the ground, hence a height value, infer. Further indications of a possible change in altitude are given by the characteristic of the radar data overall, after a more on the ground directed detection area 3 of the radar sensor 2 has certain consequences, which are further discussed below 4 will be explained in more detail.

Radar data of radar sensors 2 be through a control unit 15 ( 1 ) received and evaluated, which here as a control unit 15 a central driver assistance system is formed, and thus also functions of a security system 16 realized and therefore the security system 16 assigned. The control unit 15 centrally collects the data of all environmental sensors of the motor vehicle 1 So also the radar sensors 2 , prepares these for the functions of various driver assistance systems, in particular the safety system 16 , and performs the functions yourself.

After the control unit 15 is also designed to carry out the method according to the invention, the radar data of the radar sensors 2 also to a determination of a height value of the radar sensor 2 evaluated against the traveled surface, after which on the load state of the motor vehicle can be deduced, and thus a load state information can be determined, which is in an improved determination of collision parameters describing a possible collision, for example in braking distances, which may be longer due to higher load, collision probabilities and times to collision. The collision parameters are evaluated by means of action criteria, wherein the measures assigned to the action criteria and executed when they are executed can include the issuing of warnings to the driver and / or driving interventions and / or preconditioning of vehicle systems, in particular restraint systems.

3 shows for further explanation, the rear of the motor vehicle 1 on the one hand in an unloaded condition (solid line), in which one in the rear bumper 4 arranged radar sensor 2 in a first position 17 located. If the motor vehicle is heavily laden, in particular in the trunk, the body tilts, as by the dashed contour 19 is hinted at. The radar sensor 2 gets into a deeper position 17 ' , As can be clearly seen, the radar sensor is located 2 in the position 17 in a height value 18 over the busy ground 20 , in position 17 ' around a height value 18 ' around the busy underground 20 ,

Due to the tilting of the body of the motor vehicle 1 occurs at the front of the motor vehicle 1 the opposite effect for the contour 19 on: there will be a higher altitude for the front bumper 15 arranged radar sensors 2 be determined.

Having a larger number of radar sensors 2 is provided, resulting in an overall picture of a tilt, which indicates a certain load condition, the radar data of individual radar sensors 2 can be made plausible and / or statistically combined with each other in a simple manner. For example, at the front and at the rear three radar sensors arranged substantially at the same height with respect to the vehicle longitudinal axis 2 present, which at a tilt due to a load all the same height value 18 ' should indicate what makes it possible to plausibilize the values against each other, in particular to detect outliers, and by statistical combining the overall accuracy of the measurement of the height value 18 ' to improve. The mutual plausibility / statistical combination is of course also with the lateral radar sensors 2 possible if they are, as usual, at the same height with respect to the vehicle longitudinal axis. However, also with respect to the vehicle longitudinal axis differently positioned radar sensors or their altitude values 18 . 18 ' can be plausible against each other after the bodywork of the motor vehicle 1 is a rigid body, which tilts altogether, so that can therefore be checked whether the respective measured altitude values 18 . 18 ' to fit a common tilt.

In order to determine the loading status information, it is provided that one in the control unit 15 filed look-up table or even a map to use that from calibration measurements in different loading conditions of the motor vehicle 1 was won. For example, different, in the rear of the vehicle 1 , in the rear of the vehicle 1 or in both stored masses together with their effect on the altitude values 18 . 18 ' be measured and as a basis for establishing an association between altitude values 18 . 18 ' and loading condition information.

4 illustrates another effect of changing the loading state of the motor vehicle 1 , which can be used or taken into account in the method according to the invention. Again is the motor vehicle 1 in its normal load state (solid line) and tilted state (contour 19 ), as well as the positions 17 . 17 ' of the radar sensor 2 , In addition, the coverage areas are also included 3 . 3 ' of the radar sensor 2 for the positions 17 . 17 ' indicated. The scope of coverage covers clearly 3 ' in the slightly oversubscribed case an additional share 21 of the underground 20 , which leads on the one hand to a higher proportion of noise signals due to reflections on the ground ("bottom clutter"), but on the other hand also to a greater risk of multipath reflections, such as through the exemplary beam path 22 with respect to the object 23 shown. Consequently, the overall characteristic of the radar data changes, with reduced height of the radar sensor 2 (Position 17 ' ) a larger proportion of the underground 20 caused by noise effects and a higher risk of misdetection due to multiple reflections (multipath reflections). If there is a sufficiently clear possibility of quantifying these changes in the characteristics of the radar data, this can of course also be used to calculate the altitude values 18 . 18 ' to be determined or made plausible.

In particular, however, it is provided in the exemplary embodiment illustrated here that, depending on the actual dependent height value 18 . 18 ' and the corresponding loading state information also the evaluation of the radar data of the radar sensors 2 itself is adjusted, for example, by adjusting detection thresholds and / or algorithms to account for the "bottom clutter" and the risk of multiple reflections To detect and exclude multiple reflections, to be activated or to be parameterized more sensitively.

Finally, it should be pointed out that the plausibility check process, due to the high number of radar sensors, can also lead to a changed altitude value that does not match the other altitude values being a misalignment, ie in particular a change in the installation position of the radar sensor 2 can be detected, with the resulting misalignment information of course in the evaluation of radar data of the radar sensor 2 can be taken into account, in particular also with regard to the determination of corrected altitude values. If there is too much misalignment of a radar sensor 2 this can also be disabled and / or the driver of the motor vehicle 1 can be pointed to a necessary action.

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 non-patent literature

• Jri Lee et al., "A Fully Integrated 77-GHz FMCW Radar Transceiver in 65-nm CMOS Technology", IEEE Journal of Solid State Circuits 45 (2010), pp. 2746-2755 [0006]

Claims (11)

Method for operating a safety system of a motor vehicle ( 1 ), which security system ( 16 ) Sensor data of at least one environmental sensor of the motor vehicle ( 1 ) for determining at least one collision parameter describing a possible collision with a collision partner, and at least one measure serving the warning of the driver and / or the collision avoidance and / or collision consequences reduction, at least one measure criterion fulfilled, at least one a radar transceiver ( 12 ) semiconductor chip ( 10 ) radar sensor ( 2 ) is used, characterized in that from radar data of the at least one in at least a part of its detection range from the motor vehicle ( 1 ) traveled underground ( 20 ) detecting radar sensor ( 2 ) an altitude value ( 18 . 18 ' ) of the radar sensor ( 2 ) above the ground ( 20 ) and from all detected height values a loading state information of the motor vehicle ( 1 ), which is taken into account when determining the at least one collision parameter. Method according to claim 1, characterized in that by the semiconductor chip ( 10 ) also a control unit ( 13 ) and / or a digital signal processing component ( 14 ) of the radar sensor ( 2 ) is realized and / or the semiconductor chip ( 10 ) and an antenna arrangement ( 11 ) of the radar sensor ( 2 ) as a package ( 9 ) are realized and / or the antenna arrangement ( 11 ) is designed for the measurement of reflection angles in two mutually perpendicular planes. Method according to claim 1 or 2, characterized in that the radar sensor ( 2 ) is operated with a frequency bandwidth greater than one GHz, in particular of four GHz, and / or in a frequency range of 77 to 81 GHz. Method according to one of the preceding claims, characterized in that several, in particular three in each case on the apron and behind the motor vehicle ( 1 ) radar sensors ( 2 ) be used. Method according to one of the preceding claims, characterized in that the load state information in dependence on a in advance of the motor vehicle ( 1 ) and one at the rear of the motor vehicle ( 1 ) measured height value ( 18 . 18 ' ) and / or of several radar sensors ( 2 ) at the rear and / or at the front of the motor vehicle ( 1 ) measured altitude values ( 18 . 18 ' ) are statistically combined with each other and / or used for mutual plausibility. Method according to one of the preceding claims, characterized in that the at least one measured altitude value ( 18 . 18 ' ) is assigned a load state information by a map or a look-up table. A method according to claim 6, characterized in that for determining the map or look-up table (a calibration measurement in various load conditions of the motor vehicle 1 ) is carried out. Method according to one of the preceding claims, characterized in that in determining the altitude value ( 18 . 18 ' ) also from the underground ( 20 ), in particular by multiple reflection, originating noise components and / or misdetections are taken into account and / or the evaluation of the radar data itself is adjusted as a function of the loading state information. Method according to one of the preceding claims, characterized in that at least one plausibility criterion for excluding one by a misalignment of the radar sensor ( 2 ) erroneously changes occurring height value ( 18 . 18 ' ) is used. Method according to one of the preceding claims, characterized in that a collision probability and / or a time until the collision and / or a braking distance are used as collision parameters. Motor vehicle ( 1 ), comprising a security system ( 16 ), the sensor data of at least one environmental sensor of the motor vehicle ( 1 ) for determining at least one collision parameter describing a possible collision with a collision partner, and at least one measure serving the warning of the driver and / or the collision avoidance and / or collision consequences reduction, at least one measure criterion fulfilled, at least one a radar transceiver ( 12 ) semiconductor chip ( 10 ) radar sensor ( 2 ), wherein the safety system is a control device designed for carrying out a method according to one of the preceding claims ( 15 ) having.

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