METHOD FOR ADJUSTING CORRECTION INFORMATION IN A RADAR SYSTEM

Abstract

A method for automatically adjusting correction information in a radar system of a vehicle. The method includes: performing at least one acquisition of at least one item of acquisition information by a radar sensor, the acquisition information being specific to at least one item of angle information and one item of distance information relating to at least one detected object in an environment of the vehicle. An identification of a reference object is performed in the environment on the basis of the acquisition information. An ascertainment of the distance information relating to the reference object is performed on the basis of the acquisition information. The adjustment of the correction information is performed on the basis of the ascertained distance information relating to the reference object in order to provide a correction of the angle information.

Claims

1. A method for automatically adjusting correction information in a radar system of a vehicle, the method comprising: performing at least one acquisition of at least one item of acquisition information by a radar sensor of the radar system, wherein the acquisition information is specific to at least one item of angle information and one item of distance information relating to at least one detected object in an environment of the vehicle; performing an identification of a reference object in the environment based on the acquisition information; performing an ascertainment of the distance information relating to the reference object based on the acquisition information; and performing the adjustment of the correction information based on the ascertained distance information relating to the reference object in order to provide a correction of the angle information.

2. The method according to claim 1, wherein the correction information is implemented as information relating to an alignment of the radar sensor on the vehicle or relating to a mounting angle of the radar sensor of an elevation of the alignment in a state mounted on the vehicle.

3. The method according to claim 1, wherein the adjustment of the correction information comprises: providing the correction information from at least one prior adjustment; performing a determination of a current correction angle based on the ascertained distance information relating to the reference object; and adapting the correction information to the current correction angle, wherein the current correction angle is taken into account in a weighted manner for the correction information.

4. The method according to claim 1, wherein the correction of the angle information for the current acquisition and/or at least one subsequent acquisition of the acquisition information comprises: ascertaining the angle information through the at least one detected object based on the acquisition information; and comparing the angle information with the correction information.

5. The method according to claim 1, wherein the steps are performed repeatedly during an operation of the radar system in order to perform the adjustment of the correction information repeatedly and automatically so that the correction information is updated at every repetition.

6. The method according to claim 1, wherein the adjustment of the correction information is performed for every acquisition of the acquisition information.

7. The method according to claim 1, wherein the reference object is implemented in the manner of a ground reflection.

8. The method according to claim 7, wherein the identification is accomplished in that the reference object is chosen from the detected objects as such an object that is acquired as a stationary target and/or only during travel of the vehicle and/or under the vehicle.

9. The method according to claim 1, wherein, during the adjustment, the correction information is formed as a correction value that is specific to a correction angle, which is added to the angle information for the purpose of correction for every acquisition.

10. The method according to claim 1, wherein the reference object is implemented in the manner of a detected object with an essentially constant object height or a structure at the side of the roadway or a guardrail.

11. The method according to claim 10, wherein the identification is accomplished in that the reference object is chosen from the detected objects as such an object that is acquired as a stationary target and/or at a predetermined minimum speed of the vehicle and/or at localization of the vehicle on a predetermined route or a highway, and/or with a high signal-to-noise ratio and/or at a position to the side of the vehicle.

12. The method according to claim 10, wherein during performance of the ascertainment the distance information is ascertained in the manner of a height curve of an object height of the reference object over a distance to the reference object, and wherein, for the adjustment of the correction information, the method further comprises: determining a parameter specific to an angular deviation or a slope of the height curve; determining a correction angle based on the parameter; and adjusting the correction information based on the correction angle.

13. The method according to claim 1, wherein the adjustment of the correction information is accomplished through a comparison of the ascertained distance information and an already-known mounting height of the radar sensor on the vehicle.

14. A radar system for a vehicle for detection of an object in an environment of the vehicle, the radar system comprising: an acquisitor to acquire at least one item of acquisition information by a radar sensor of the radar system, wherein the acquisition information is specific to at least one item of angle information and one item of distance information relating to at least one detected object in the environment of the vehicle; an identifier to identify a reference object in the environment based on the acquisition information; an ascertainer to ascertain the distance information relating to the reference object based on the acquisition information; and an adjuster to adjust correction information based on the ascertained distance information relating to the reference object in order to provide a correction of the angle information.

15. The radar system according to claim 14, wherein the radar system comprises a processing device, in particular with a computer program, wherein the processing device comprises the acquisitor and/or the identifier and/or the ascertainer and/or the adjuster.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

[0030] FIG. 1 is a schematic representation for visualizing a method according to the invention,

[0031] FIG. 2 is a schematic side view of a vehicle with a radar system according to the invention,

[0032] FIG. 3 is a schematic representation of parts of a radar system according to the invention,

[0033] FIG. 4 is a representation for visualizing a correction angle,

[0034] FIG. 5 is a representation to illustrate an adjustment in accordance with the method according to the invention.

DETAILED DESCRIPTION

[0035] In FIG. 1, the steps of a method according to the invention are visualized schematically. The method here serves the automatic adjustment 204 of correction information 115 in a radar system 5 of a vehicle 1. According to a first method step 201, an acquisition of at least one item of acquisition information 100 is accomplished by a radar sensor 6 of the radar system 5. In this case the acquisition information 100 can be specific to at least one item of angle information 106 and one item of distance information 105 relating to at least one detected object 2 in an environment 50 of the vehicle. In other words, the distance information 105 relating to a distance to the detected object 2 and the angle information 106 relating to an angle (i.e., a direction) of the object 2 relative to the radar sensor 6 can be ascertained from the acquisition information 100 using methods that are known per se for such radar systems. The angle can correspond, in particular, to the angle of incidence on the radar sensor 6 of the radar signals reflected by the object 2. It is likewise known that a speed of the object 2 relative to the radar sensor 6 can be ascertained from the acquisition information 100.

[0036] In the radar system 5 according to the invention, the acquisition 201 can be possible by the means that the radar system 5 and, in particular, the radar sensor 6 emits a radar signal that is reflected by the at least one object 2 and can then be received by the radar sensor 6. For this purpose, the radar sensor 6 can have multiple antennas that each receive the radar signal. In this way, the angle information 106 can be determined reliably on the basis of a time-of-flight or phase difference of the received radar signals (among one another). The radar system can be implemented, by way of example, as a continuous wave radar, in particular FMCW radar (frequency modulated continuous wave radar), so that the emitted radar signal can have a frequency-modulated signal form. In concrete terms, the emitted radar signal can be implemented as a chirp signal. The acquisition information 100 can be obtained by, e.g., down-conversion of the received radar signal to baseband and subsequent digitization, e.g. by an analog-to-digital converter. Additional or different processing steps are of course also encompassed by the invention.

[0037] Once the acquisition information 100 is on hand, according to a second method step 202 an identification of a reference object 3 in the environment 50 can subsequently be performed on the basis of the acquisition information 100. For example, the detected objects 2 with the associated distance, angle, and/or speed information can be ascertained through a processing of the acquisition information 100, such as at least one frequency transformation. For identification 202 of the reference object 3, provision can be made that the detected objects 2 are analyzed on the basis of predetermined criteria. For example, only those objects 2 whose angle information 106 indicates a negative angle, and thus are located under the vehicle 1, are taken into account. In this way, the reference object 3 is identified as a particular object 2, such as a ground level. It is possible here that other object types also come into consideration as reference object 3 provided that they have a defined property with regard to the object height and/or a distance characteristic to the radar sensor 6 and thus are suitable as a reference for the angle information 106.

[0038] Then, according to a third method step 203, an ascertainment 203 of the distance information 105 relating to the reference object 3 can be performed on the basis of the acquisition information 100. In other words, at least one distance that the reference object 3 has to the radar sensor 6 is ascertained. This can be a single distance value or different distance values in this case. The different distance values can be determined in the case of an extensive reference object 3 such as a guardrail, for example. It is also possible that the different distance values are ascertained over time during travel of the vehicle 1.

[0039] According to a fourth method step 204, a performance of the adjustment 204 of the correction information 115 is accomplished on the basis of the ascertained distance information 105 relating to the reference object 3 in order to provide a correction of the item(s) of angle information 106 (i.e., for the current and/or additional angle information). It is therefore possible to correct the angle information 106 of additional detected objects 2 on the basis of the correction information 115 and, in particular, on the basis of the distance information 105 relating to the reference object 3.

[0040] The correction can be necessary because the exact alignment of the radar sensor 6 on the vehicle 1 is not known after mounting of the radar sensor 6 on account of tolerances and the like. In other words, the mounting angle or—in more general terms—the mounting position is unknown. However, the mounting height of the radar sensor 6 on the vehicle 1 can be known. The correction information 115 can accordingly be implemented as information relating to a mounting angle of the radar sensor 6, in particular an elevation of an alignment in a state mounted on the vehicle 1 and/or of a mounting position error.

[0041] In FIG. 2, this correlation is illustrated further. The radar sensor 6 here is mounted on the vehicle 1 at an already-known height h. A tilt of the radar sensor 6 can be seen, which is indicated in FIG. 4 with the angle 110, hereinafter called correction angle 110. Possible reference objects 3, such as a ground level at which the vehicle 1 is located, or a structure to the side on the shoulder of the road are also represented schematically.

[0042] Shown in FIG. 3 is that the method according to the invention can also be carried out by a processing device 300 such as a control unit of the vehicle 1. To this end, the processing device 300 can have an acquisitor 301 for performing the acquisition 201, an identifier 302 for performing the identification 202, an ascertainer 303 for performing the ascertainment 203, and an adjuster 304 for performing the adjustment 204. The various components 301-304 can be implemented as separate components or as one common component that is suitable for executing a computer program. Accordingly, the processing device 300 can be implemented as a data processing device such as a computer.

[0043] The adjustment 204 of the correction information 115 can be accomplished by the means that the previous correction information 115 from at least one prior adjustment is first provided. If there is no prior adjustment, then a predefined initial value can also be used, and/or the correction information 115 can be determined initially from the correction angle 110 described below. Then a performing of a determination of a current correction angle 110 can occur on the basis of the ascertained distance information 105 relating to the reference object 3. After that, an adapting of the correction information 115 to the current correction angle 110 occurs, wherein the current correction angle 110 can be taken into account in a weighted manner for the correction information 115. As a result, past values of the correction information 115 receive a higher weighting than current values so that an error tolerance can be increased.

[0044] According to FIG. 4 the correction of the angle information 106 for the acquisition 201 and/or at least one subsequent acquisition 201 of the acquisition information 100 can be accomplished by the steps that first an ascertaining of the angle information 106 relating to the at least one detected object 2 is performed on the basis of the acquisition information 100 in order to then compare this angle information 106 with the correction information 115. In concrete terms, the correction information 115 can be implemented here as a correction value that is specific to a correction angle 110 which is added to the angle information 106 for the purpose of correction for the acquisition 201. This is useful especially when the reference object 3 is implemented in the manner of a ground reflection—which is to say ground level 3. In this case, the following distance relationship can be utilized:

sin(a)=h/R,

[0045] where h denotes the shortest distance between the radar sensor 6 and the ground level 3, which is to say the height, and R denotes the distance between the radar sensor 6 and the ground level 3 corresponding to the radar signals reflected by the ground level 3. The value for h can be known in advance and/or be measured after mounting of the radar sensor 6, and R can be ascertained from the distance information 105 relating to the detected reference object 3 on the basis of the acquisition information 100. The angle a here denotes the reference angle 111, which is to say, in particular, an angle of incidence of the reflected radar signals relative to a horizontal plane. The (current) correction angle 110 can be ascertained from this, for example as the difference between the calculated angle a and the angle information 106 relating to the reference object 3 that is ascertained from the acquisition information 100—which is to say measured. The correction angle 110 can then serve to perform the correction for additional detected objects 2 by an addition to the angle information 106. This correction is especially reliable owing to the use of the mathematically robust distance relationship. The more inaccurate speed relationship between the reference object 3 and the radar sensor 6 can indeed be used for classification of the reference object 3, which is to say for identification, but is not needed beyond that for the determination of the correction angle 110. As a result, the reliability can be further improved.

[0046] In addition, the reference object 3 can optionally be implemented in the manner of a structure at the side of the roadway, in particular a guardrail or the like. According to FIG. 5, the distance information 105 can be ascertained in the manner of a height curve of the object height ho of the reference object 3 over an increasing distance R to the reference object 3 during performance of the ascertainment 203. The acquisition information 100 can be adversely affected by noise so that the measured height values of the object height ho are scattered accordingly (indicated by the points in FIG. 5). Provision can therefore be made that an approximation such as a linear regression is calculated from the height values in order to obtain the illustrated height curve with a constant slope. The ideal relationship between the object height ho of the reference object 3, the elevation angle b to the reference object 3 ascertained from the angle information 106, and the distance R to the reference object 3 ascertained from the distance information 105 is, e.g., the following here:

ho=h(i.e., height of the sensor)+R*sin(b)

[0047] In the case of an ideal alignment of the radar sensor 6 at the horizontal, the object height ho of the reference object 3 would not change for different distances R to the reference object 3. It can be seen in FIG. 5, however, that the curve of the object height ho changes over the different distances R, and thus a slope is present that is not equal to 0. For very small elevation angles b, it is the case here that the slope corresponds approximately to the correction angle 110 (clearly visible in FIG. 4). The slope can thus be used to determine the correction angle 110 and thus also to adjust the correction information 115 for correction of the angle information 106 of additional objects 2.

[0048] The above explanation of the embodiments describes the present invention solely within the framework of examples. Individual features of the embodiments can of course be combined freely with one another, insofar as is technically appropriate, without departing from the scope of the present invention.

[0049] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.