Method for measuring the orientation of the emission direction of radar sensors in a motor vehicle

Abstract

Method for measuring the orientation of the emission direction of radar sensors in a motor vehicle. The motor vehicle is located in a vehicle test stand (301) for the purpose of conducting a test bench run. The vehicle is designed such that the radar sensor emits radar beams and, during the operation of the motor vehicle, receives radar beams reflected from objects in the vicinity of the motor vehicle. For the execution of the method, the position and orientation of the motor vehicle are defined in a coordinate system of the vehicle test stand (301). According to the present invention, the position and orientation of at least one measuring surface (303) are defined in the coordinate system of the vehicle test stand (301). The measuring surface (303) is divided into several measuring points, which are horizontally and vertically spaced apart from one another.A sensor unit is provided for measuring the intensity of the radar beams emitted by the vehicle sensor at one or more measurement points on the measuring surface (303). If the sensor unit does not measure the intensity of the radar beams at all measurement points on the measuring surface (303) at a single time, its position (Y, Z) on the vehicle test bench (301) can be changed so that the intensity of the radar beams is measured at multiple points on the measuring surface (303). By comparing the measured intensities at the measurement points on the measuring surface (303) and evaluating symmetries in the measured intensities at the individual measurement points on the measuring surface (303), the intersection point of the radiation direction of the radar sensor of the vehicle on the test bench with the measuring surface (303) is determined.

Description

[0001] The present invention relates to a method for measuring the orientation of the radiation direction of radar sensors in a motor vehicle according to the preamble of claim 1.

[0002] It is known to position motor vehicles in a vehicle test bench for conducting test runs. Such a vehicle test bench has wheel mounts for the vehicle's wheels. The wheel mounts are designed so that they each have at least one drivable and brakeable roller on which the vehicle's wheel rests. Forces can be applied to the respective vehicle wheel via the drivable and brakeable roller.

[0003] During a test bench run, the vehicle's wheels remain on the wheel mounts of the vehicle test bench. The wheel mounts of the vehicle test bench have one or two drivable rollers. Using these drivable rollers, the vehicle test bench can simulate the vehicle's journeys in a real environment by simulating the forces acting on the vehicle's wheels when the vehicle moves from the road using the rollers of the wheel mounts.

[0004] In order to be able to realize steering movements of the motor vehicle during the test bench drive, the rollers of at least the wheel hubs for the steered wheels of the motor vehicle can also be rotatable about the vertical axis.

[0005] The vehicle test bench can be designed for single-track motor vehicles (motorcycles) or for multi-track motor vehicles.

[0006] Motor vehicles are commonly equipped with sensors for detecting their surroundings. The sensor signals are subsequently evaluated by control units to assess the vehicle's surroundings. These sensors can be cameras or radar sensors. It is known to design a vehicle test bench in such a way that the vehicle's sensors are stimulated with specific scenes from an environmental simulation during the test bench drive. For this purpose, screens are provided for the vehicle's cameras in the vehicle test bench. These screens display scenes that the vehicle's cameras would "see" if it were not a test bench drive, but if the vehicle were driving in a real environment with the driving conditions resulting from the test bench drive.

[0007] In this context, it is known that the vehicle's radar sensor can also be stimulated with environment-simulated scenes. So-called radar target simulators (RTS) are used for this purpose. These radar target simulators absorb incoming radar beams and actively emit radar beams that correspond to environment-simulated scenes.

[0008] The radar sensor of the motor vehicle emits radar beams and receives radar beams reflected from objects in the surroundings of the motor vehicle while the motor vehicle is driving.

[0009] The present invention is based on the object of measuring the orientation of the radiation direction of radar sensors of motor vehicles in a vehicle test bench.

[0010] The radiation direction of the radar sensor corresponds to the orientation of a symmetry axis of the radar sensor. > This axis of symmetry of the radar sensor corresponds to the central axis of the main lobe when only one radar beam (radar lobe) is emitted. > If several radar lobes are emitted by a radar sensor, the radiation direction of the radar sensor is such that the main axes of the individual radar lobes are distributed symmetrically around the radiation direction of the radar sensor.

[0011] It has been shown that measuring the orientation of the radiation direction of the radar sensor of a motor vehicle offers advantages when simulating the environment of the motor vehicle during a test bench drive.

[0012] This measurement of the orientation of the radiation direction of radar sensors of motor vehicles proves to be advantageous for the stimulation of the radar sensor of the motor vehicle

[0013] This allows the RTS or its antenna to be positioned with greater accuracy in the vehicle test bench compared to a situation where certain boundary conditions are assumed to be met, and the RTS can then be positioned according to the specified boundary conditions. For a specific RTS position, knowing the radar sensor's radiation direction also allows the signal to be output by the RTS to be adjusted.

[0014] By measuring the orientation of the radiation direction of the motor vehicle's radar sensor with respect to the motor vehicle's coordinate system, the correct setting (adjustment) of the radar sensor can be checked. This will be explained in more detail below in connection with claim 7.

[0015] In the present invention, this measurement of the orientation of the radiation direction of the motor vehicle's radar sensor can advantageously be performed without communication with the motor vehicle's radar control units – in contrast to the prior art. This advantageously makes it possible to determine the orientation of the radiation direction of radar sensors for different motor vehicle types – even from different motor vehicle manufacturers – without requiring access to internal vehicle data from the vehicle's control units.

[0016] The motor vehicle is located in a vehicle test bench for conducting a test drive. The radar sensor emits radar beams in order to receive radar beams reflected from objects in the vehicle's surroundings while the motor vehicle is driving. The position and orientation of the motor vehicle are defined in a coordinate system of the vehicle test bench. According to the present invention, the position and orientation of at least one measuring surface are defined in the coordinate system of the vehicle test bench. The measuring surface is divided into several measuring points that are spaced apart horizontally and vertically. A sensor unit is provided with which the intensity of the radar beams emitted by the vehicle sensor is detected at one or more measuring points on the measuring surface.The position of the sensor unit in the vehicle test bench (301) can be changed (Y, Z) such that the intensity of the radar beams is recorded at several measuring points on the measuring surface. If the sensor unit records the intensity of the radar beams at all measuring points on the measuring surface at one time, this changeability of the position (Y, Z) of the sensor unit in the measuring surface is not necessary. By comparing the measured intensities at the measuring points on the measuring surface and evaluating symmetries in the measured intensities at the individual measuring points on the measuring surface, a point of intersection of the radiation direction of the radar sensor of the motor vehicle in the vehicle test bench with the measuring surface (303) is determined.

[0017] To measure the vehicle's radar sensor relative to the vehicle's coordinate system, the position and orientation of the vehicle in the vehicle test bench must be defined by positioning or measuring. From this positioning or measuring, the position and orientation of the vehicle in the vehicle test bench (i.e., in the vehicle test bench's coordinate system) are known at any given time.

[0018] For this purpose, a coordinate system is assigned to the vehicle test bench.

[0019] With regard to the wheel mounts of the vehicle test bench, a sensible definition of the coordinate system of the vehicle test bench is if, in the case of a vehicle test bench for a multi-track motor vehicle, the X-axis of the coordinate system extends in the middle between, on the one hand, the wheel mounts for the wheels on the left side of the motor vehicle and, on the other hand, the wheel mounts for the wheels on the right side of the motor vehicle.

[0020] In a vehicle test bench for a single-track motor vehicle (e.g. a motorcycle), the X-axis advantageously extends as a connecting line between the center of the front and rear wheel mounts of the vehicle test bench.

[0021] In a vehicle test bench for a multi-track motor vehicle, the Y-axis extends as an extension of the connecting line between the wheel hubs for the left front wheel of the motor vehicle and the right front wheel of the motor vehicle.

[0022] In a vehicle test bench for a single-track motor vehicle, the Y-axis in the horizontal plane intersects vertically the X-axis of the coordinate system of the vehicle test bench in the wheel hub of the front wheel.

[0023] The Z-axis logically extends through the intersection point of the X-axis and the Y-axis in the vertical direction.

[0024] When the motor vehicle is positioned on the wheel hubs of the vehicle test bench, the symmetry axis of the motor vehicle coincides with the X-axis of the coordinate system of the vehicle test bench.

[0025] When the vehicle is measured on a vehicle test bench, both the vehicle's axis of symmetry and the geometric driving axis (defined as the bisector of the toe angles of the vehicle's non-steering wheels) can be determined relative to the vehicle test bench's coordinate system. The deviation between the vehicle body's axis of symmetry and the geometric driving axis is referred to as the vehicle's "dachshund run" and is often negligible.

[0026] The position and orientation of the motor vehicle in the vehicle test bench can also be defined by specifically positioning the motor vehicle in the vehicle test bench and then controlling it at this position. This control can be achieved by providing drive means by which the wheel hubs can each be rotated about a vertical axis. This allows forces to be introduced onto the wheels of the motor vehicle via the rollers of the wheel hubs, which forces position the motor vehicle in the vehicle test bench. In particular, this makes it possible to keep the position and orientation of the motor vehicle constant in the vehicle test bench so that the geometric driving axis or the axis of symmetry of the motor vehicle constantly coincides with the X-axis of the coordinate system of the vehicle test bench.

[0027] According to the present invention, in order to solve the problem, the position and orientation of at least one measuring surface are defined in the coordinate system of the vehicle test bench.

[0028] Within the scope of the present invention, it is not necessary for this surface to be formed by a physical object. It is also within the scope of the invention that the sensor unit explained below is positioned in such a way that the intensity of the radar beams is detected at defined measuring points on the measuring surface.

[0029] In general, the measuring surface can be curved. However, the evaluation of the measurement data is much easier if the measuring surface is flat. Further information on the positioning and orientation of the measuring surface can be found in the other dependent claims.

[0030] The measuring area is divided into several measuring points that are spaced horizontally and vertically from each other.

[0031] Furthermore, a sensor unit is provided with which the intensity of the radar beams emitted by the vehicle sensor is recorded at one or more measuring points of the measuring area.

[0032] The sensor unit can be designed so that it only detects the intensity of the radar beams at one measuring point on the measuring surface. In this case, the sensor unit is shifted accordingly in the coordinate system of the vehicle test bench to detect the intensities at all measuring points on the measuring surface.

[0033] The sensor unit can also be designed to detect the intensity of the radar beams at multiple measurement points simultaneously. The sensor unit detects the intensities of the radar beams in the measurement area, similar to a digital camera, such that one pixel of the digital camera corresponds to one measurement point in the measurement area. ➢If these multiple measuring points are all measuring points of the measuring area, the sensor unit does not need to be moved to record the intensities of the radar beams in the measuring points of the measuring area. ➢If these multiple measurement points do not include all measurement points of the measurement area, the sensor unit is shifted in the coordinate system of the vehicle test bench so that the intensities of the radar beams at additional measurement points of the measurement area are recorded through several consecutive measurements. The sensor unit still needs to be shifted, but fewer "shifting operations" of the sensor unit are required compared to a sensor unit design in which the intensity of the radar beams is recorded at only one measurement point during a single measurement.

[0034] The position of the sensor unit can therefore be changed in the vehicle test bench in such a way that the intensity of the radar beams is recorded at several measuring points of the measuring area - unless the sensor unit records the intensity of the radar beams at all measuring points of the measuring area at one time.

[0035] The intensities can be recorded at all measuring points of the measuring area.

[0036] When measuring the intensities in a measuring area, the present method only requires the detection of one or more local maxima of the intensities of the radar beams in the measuring area.

[0037] In the present method, an intersection point of the radiation direction of the radar sensor of the motor vehicle located in the vehicle test bench with the measuring surface is determined by comparing the measured intensities in the measuring points of the measuring surface and by evaluating symmetries in the measured intensities in the individual measuring points of the measuring surface.

[0038] Advantageously, the radiation direction of the radar sensor of the motor vehicle in the coordinate system of the vehicle test bench can be derived from the relationship between the position and orientation of the measuring surface in the coordinate system of the vehicle test bench.

[0039] The present invention is not about measuring the shape of the radar beam, but rather the radiation direction of the radar sensor. ➢If the radar sensor emits only one radar beam, this is the axis of the main beam of the radar sensor. ➢If the radar sensor emits two or more radar beams, the radar beams overlap. This means that the intensities of the radar beams overlap at every point in space. The points at which a local maximum of the radar radiation intensity is measured then no longer lie on one of the axes of the individual radar beams. Due to the superposition of the intensities, these points are shifted. Nevertheless, the radiation direction of the radar sensor can be determined using the averaging described in claims 2 and 3 - the second alternative in each case - because the "shift" of the local maxima of the intensities is symmetrical to the radiation direction of the motor vehicle's radar sensor in such a way that these "shifts" compensate for each other when determining a center point of the local maxima.The center point then no longer depends on the exact shape of the radar lobes and how much the radiation directions of the individual radar lobes differ from each other. For the purposes of the present invention, the exact shape of the individual radar lobes is no longer important, because the purpose of the measurement is achieved by averaging to determine the center point from the local maxima in the individual measurement planes.

[0040] Claim 2 describes an embodiment of the method in which it is initially not known whether the radar sensor of the motor vehicle emits one radar beam or several radar beams.

[0041] Therefore, in the embodiment of the method according to claim 2, it is first determined for the measuring points of the measuring surface whether a local maximum of the measured intensities of the radar beams in the measuring points exists only in one of the measuring points of the measuring surface.

[0042] If a local maximum is detected in only one of the measuring points, it is concluded that the vehicle's radar sensor is only emitting a radar beam.

[0043] If several local maxima of the measured intensities of the radar beams are detected in the measuring points of the measuring area, it is concluded that the radar sensor of the motor vehicle emits several radar beams.

[0044] The method according to claim 2 is therefore suitable for conducting regularly recurring general inspections on motor vehicles to conduct technical tests to determine the roadworthiness of the vehicle. A wide variety of vehicle types from different vehicle manufacturers are subjected to these general inspections. Not all vehicle manufacturers provide corresponding information on the details of the sensors installed.

[0045] Advantageously, the method according to claim 2 makes it possible to first measure and evaluate the functioning of the radar sensor of the motor vehicle to the necessary extent (emitting only one radar beam or emitting several radar beams).

[0046] The method according to claim 3 describes the procedure according to the present invention compared to the method according to claim 2 if the information is available for the motor vehicle to be examined as to whether the radar sensor emits only one radar lobe or whether the radar sensor emits several radar lobes.

[0047] If it is determined with the first method step according to claim 2 or with the information available for the motor vehicle to be examined that only one radar lobe is emitted by the radar sensor, both in the method according to claim 2 and in the method according to claim 3, as a first alternative in the further method, the measuring point in the measuring area in which the maximum of the intensity of the radar beams was measured is determined as the intersection point of the radiation direction of the radar sensor of the motor vehicle located in the vehicle test bench with the measuring area.

[0048] If it is determined with the first method step according to claim 2 or with the information available for the motor vehicle to be examined that several radar beams are emitted by the radar sensor, both in the method according to claim 2 and in the method according to claim 3, as a second alternative in the further method, a center point for the measuring points with the local maxima of the intensities of the radar beams is determined as the intersection point of the radiation direction of the radar sensor of the motor vehicle located in the vehicle test bench with the measuring surface.

[0049] In the method according to claim 4, the measuring surface is flat. Furthermore, the surface normal of the measuring surface extends in a direction parallel to the longitudinal direction (axis of symmetry) of the motor vehicle in the vehicle test bench (X).

[0050] It has been shown that with this definition and positioning of the measuring surface, the signal evaluation can be carried out easily.

[0051] According to the definition of the vehicle test bench's coordinate system explained above, this direction corresponds to the X-axis of the vehicle test bench's coordinate system. The measuring surface thus runs parallel to a surface spanned by the Z-axis and Y-axis of the vehicle test bench's coordinate system at each individual position.

[0052] This design of the measuring surface simplifies the evaluation compared to a curved measuring surface arranged with an asymmetrical orientation in the vehicle test bench. Evaluation is also possible under these conditions, but requires greater effort in evaluating the measurements.

[0053] In the embodiment of the method according to claim 5, the distance of the measuring surface from the motor vehicle located in the vehicle test bench can be set to different values ​​(X).

[0054] Advantageously, for each of the distances, the respective intersection point of the radiation direction of the radar sensor to the measuring surfaces in the respective position in the X-direction can be determined.

[0055] The embodiment of the method according to claim 6 is a further development of the method according to claim 5. In the method according to claim 6, a connecting line of the intersection points determined at the different distances (X1, X2, X3, X4) of the measuring surface is determined as part of a straight line on which the radar sensor is arranged at the intersection points of the radiation direction of the radar sensor of the motor vehicle located in the vehicle test bench with the measuring surfaces set to the different distances of the respective measuring surfaces to the motor vehicle located in the vehicle test bench.

[0056] This allows the radiation direction of the vehicle's radar sensor to be determined in the coordinate system of the vehicle test bench.

[0057] The radar sensor is located on an extension of this connecting line beyond the point determined at the X-position of the measuring surface closest to the radar sensor. Therefore, the connecting line is part of this straight line because it represents an extension of the connecting line.

[0058] This allows the straight line on which the radar sensor is arranged in the coordinate system of the vehicle test bench to be determined with little effort, provided that the corresponding symmetries and geometric conditions of the arrangement of the measuring surface in the coordinate system of the vehicle test bench and a corresponding positioning of the motor vehicle in the vehicle test bench.

[0059] This straight line corresponds to the orientation of the radiation direction of the vehicle's radar sensor.

[0060] The X-coordinate of the radar sensor is assumed to be known. This X-coordinate can be measured when the vehicle is in the vehicle test bench.

[0061] The position and radiation direction of the vehicle's radar sensor in the vehicle test bench's coordinate system are determined from the course of the straight line and the X-coordinate.

[0062] If the measuring surface is positioned at more than two specific distances from the vehicle, rather than just two specific distances, it becomes possible to improve the accuracy with which the orientation of the line in the vehicle's coordinate system can be determined. If a line is defined by only two points, any errors in determining the points will directly affect the orientation of the line. If more than two points are determined, the orientation of the line can be determined using suitable statistical methods—for example, the least squares method—in such a way that measurement errors are at least partially compensated.

[0063] In the embodiment of the method according to claim 7, if a tolerance range for the angle between, on the one hand, the connecting line and, on the other hand, the axis of symmetry of the motor vehicle and / or the geometric driving axis of the motor vehicle is exceeded, an error signal is output for the adjustment of the radar sensor.

[0064] With optimal settings and adjustment of the radar sensor, its radiation direction coincides with (or runs parallel to) the vehicle's axis of symmetry or the vehicle's geometric driving axis. The tolerance range is defined by the maximum deviation that an angle between the radar sensor's radiation direction and the vehicle's axis of symmetry or the vehicle's geometric driving axis is permitted.

[0065] Advantageously, the method according to claim 7 can be used to detect whether the radar sensor of a motor vehicle is misaligned. Whether the orientation of the determined connecting line is evaluated relative to the symmetry axis of the motor vehicle or relative to the geometric driving axis of the motor vehicle depends on which of the two variables is used to determine the position and orientation of the motor vehicle in the coordinate system of the vehicle test bench.

[0066] The method according to claim 7 makes it possible to test the road safety of a motor vehicle with regard to the proper adjustment of sensors, whose signals are subsequently used, among other things, in vehicle systems known as ADAS, which are relevant to road safety. For example, the radar sensor adjustment can be checked as part of the cyclical general inspection of motor vehicles.

[0067] In the embodiment of the method according to claim 8, when carrying out a test bench drive, the radar sensor of the motor vehicle is stimulated, in which the parameters of the straight line to which the connecting line is a component of this straight line are taken into account when positioning a radar target simulator and / or determining the radar beams emitted by the radar target simulator.

[0068] With the embodiment of the method according to claim 8, it is possible to carry out the positioning and / or the determination of the radar signal to be emitted by the radar target simulator in the vehicle test bench in such a way that the environmental simulation for the test bench drive is adapted to a possible deviation of the radiation direction of the radar sensor from the symmetry axis of the motor vehicle or from the geometric driving axis of the motor vehicle.

[0069] It should be noted that the radar sensor of a motor vehicle - unlike, for example, a camera of a motor vehicle - is not a purely passive sensor to which an environment simulation is presented so that it can be checked whether this environment simulation is correctly recognized or not.

[0070] Unlike a purely passively observing camera, the vehicle's radar sensor initially emits one (or more) radar beams, which trigger (at least some) objects in the surrounding area to "return" reflected radar beams depending on the incident radar beams. In an environment with defined objects and a defined speed (vector-like) relative to a stationary reference system, the simulation of the surrounding area depends on which radar beams hit the respective object. In this respect, the objects can be interpreted as "active transmitters" that emit radar beams that depend on: > of the objects and their speed relative to a stationary reference system and > from the radar beams of the vehicle's radar sensor.

[0071] For example, by separately determining the X-coordinate of the radar sensor of the motor vehicle in the coordinate system of the vehicle test bench, the radar target simulator (or its antenna) can be positioned not only in an optimal alignment with the radar sensor of the motor vehicle in the vehicle test bench, but also at a precisely defined distance in front of the radar sensor of the motor vehicle in the vehicle test bench.

[0072] An embodiment of the invention is illustrated in the drawing. It shows: Fig. 1: an example representation of a motor vehicle with a marking of an area in which a radar sensor is usually installed to detect the area in front of the motor vehicle, Fig. 2: a principle diagram of the measurement in a rectangular (e.g. square) measuring area, Fig. 3: an example of a vehicle test bench with the definition of a coordinate system and the positioning of a flat measuring surface in the vehicle test bench, Fig. 4 - 7: different curves of the intensities of the radar beams in the measuring points of the measuring surface at different distances of the measuring surface from the vehicle in the vehicle test bench, Fig. 8: a representation of the evaluation of the measured intensities in the sense of claim 6, Fig. 9: an example of the procedure for determining the intersection point of the radiation direction of the radar sensor of a motor vehicle with the measuring surface and Fig. 10: an example of the procedure for checking whether the angle between the radiation direction of the radar sensor of the motor vehicle and the symmetry axis of the motor vehicle or the geometric driving axis of the motor vehicle is above a tolerance threshold.

[0073] Fig. Figure 1 shows an example representation of a motor vehicle 1 with a marking 2 of an area in which a radar sensor is typically mounted to detect the area in front of the vehicle. This area determines the respective size of the measuring area with respect to the measuring points to be measured, depending on the distance of the measuring surface from the vehicle and the typical radiation angle of the radar beam (main lobe).

[0074] Fig. Figure 2 shows a schematic diagram of the measurement in a rectangular—in this case, square—measurement area, with each corner of the partial rectangles representing a measurement point. The intensities of the radar beams at the measurement points can be measured sequentially, as shown by the arrows.

[0075] The starting point in the example shown is the position P0, from which the Fig. 2 is “driven” diagonally to the bottom left to the measuring point P1, which is in the Fig. 2 is located at the bottom left. When measuring points cross, the intensity of the radar beams is measured.

[0076] From there, the measuring points are traversed counterclockwise according to the arrows on rectangles starting from the corner points P1, P2 and P3.

[0077] This allows you to access all measuring points on the measuring surface.

[0078] Fig. 3 shows an example of a vehicle test bench 301 with the definition of a coordinate system 302 and the positioning of a flat measuring surface 303 in the vehicle test bench 301.

[0079] The four wheels of a motor vehicle are visible, located in the vehicle test stand 301 and resting on the wheel mounts (not shown here). Only wheel 304 is provided with a reference number.

[0080] The dashed line shows the measuring surface 303 in one position.

[0081] According to the arrows at the end of the dashed line, a sensor for measuring the intensity of the radar beams in the measuring area 303 can be moved in the Y and Z directions in order to measure the intensity of the radar beams in the measuring points of the measuring area 303 - for example according to Fig. 2 - to record.

[0082] By shifting the measuring surface 303 in the X-direction, the measurement of the intensity of the radar beams in the measuring surface can be carried out at different distances of the measuring surface 303 from the motor vehicle in the vehicle test bench.

[0083] The Fig. 4 to 7 show representations of the intensity measurement in the measuring surface at different distances of the measuring surface 303 from the motor vehicle in the vehicle test bench.

[0084] The measuring surface can be positioned at different distances from the motor vehicle in the vehicle test bench by moving the sensor unit in the X direction according to the crossed arrow 305.

[0085] The Fig. 4 to 7 show different curves of the intensities in the measuring points of the measuring surface 303 with increasing distances in the X-direction of the measuring surface 303 from the motor vehicle in the vehicle test bench 301.

[0086] In the diagrams of the Fig. In figures 4 to 7, the measured intensity of the radar beams is plotted along the ordinate of the diagrams. In the example shown, the intensity is plotted in dB. The value range on the ordinate of the diagrams extends from: ➢-65 at the lower end of the scale up to ➢-20 at the top end of the scale.

[0087] The abscissa of the diagrams corresponds to the Y-coordinate of the respective measuring point in the coordinate system of the vehicle test bench 301. The value range here extends, for example, from: ➢-800 mm at the left end of the abscissa of the diagrams up to ➢+800 mm at the right end of the abscissa of the diagrams.

[0088] In the example shown, two radar beams (radar lobes) are emitted by the vehicle's radar sensor.

[0089] The two local maxima can be seen, which are measured by the superposition of the intensities of the radar beams in the measuring points of the measuring area 303.

[0090] In the diagram of the Fig. 4 the measuring surface 303 was at a distance X1=2000 mm in front of the vehicle's radar sensor.

[0091] In the diagram of the Fig. 5 the measuring surface 303 was at a distance X2=2600 mm in front of the vehicle's radar sensor.

[0092] In the diagram of the Fig. 6 the measuring surface 303 was at a distance X3=3000 mm in front of the vehicle's radar sensor.

[0093] In the diagram of the Fig. 7 the measuring surface 303 was at a distance X4=3200 mm in front of the vehicle's radar sensor.

[0094] Fig. Figure 8 shows a representation of the evaluation of the measured intensities in the sense of claim 4.

[0095] On the abscissa of the diagram of the Fig. 8 shows the X-coordinate of the measuring surface (303) in the coordinate system of the vehicle test bench. The value range of the diagram shown on the abscissa extends from 0 mm to 3500 mm. Based on the entered measuring points, the values ​​of the X-coordinate of the measuring surfaces when recording the individual diagrams are to be calculated according to the Fig. 4 to 7 can be seen.

[0096] On the ordinate of the diagram of the Fig. 8 shows the Y-coordinate of the measuring area(s) 303 at the different X-coordinates.

[0097] The measurement points are represented by the squares in the upper and lower curves of the diagram of the Fig. 8. These squares mark the XY coordinates of the local maxima of the measured intensities of the radar beams at the measuring points of the measuring area 303.

[0098] The marked points of the middle curve in the diagram of the Fig. 8 shows the calculated center point of the two local maxima in the respective measurement area at the corresponding X-coordinate. This calculated center point thus yields the Y-coordinate of the center point of the local maxima of the radar beam intensity at a defined X-coordinate of the measurement area 303.

[0099] The dashed line in the diagram of the Fig. 8 is the regression line obtained by statistical methods (least squares method) from the points of the middle curve of the diagram of the Fig. 8. The equation of the straight line is: Y=0.0011*X−18.8 of the local mean values ​​as a function of the distance X (abscissa) from the radar sensor (X=0). The ordinates are the Y values ​​of the center of the local maxima of the radar beam intensities depending on the distance X of the measuring surface from the radar sensor (X=0).

[0100] The slope of the regression line arctan(0.0011) = 0.063 [degrees] is the measure for the orientation of the radiation direction of the radar sensor of the motor vehicle in the coordinate system of the vehicle test bench - and thus also to the symmetry axis of the motor vehicle or the geometric driving axis of the motor vehicle.

[0101] The Y value at X=0 describes the origin of the radar radiation from the vehicle's radar sensor. In the example shown, this Y value is: Y=−18.8

[0102] This means that the radiation source of the radar sensor is not mounted centrally in the vehicle, but offset laterally to the symmetry axis of the vehicle or the geometric driving axis of the vehicle.

[0103] To carry out a test bench drive, the radar sensor of the vehicle can be stimulated, ➢by positioning a radar target simulator (or its antenna) in the X-direction at a defined distance from the X-position of the radar sensor with the Y, Z coordinates determined for the exit point of the radar beams from the radar sensor and / or ➢by determining the signals emitted by the radar target simulator depending on the parameters of the determined regression line.

[0104] Fig. Figure 9 shows an example of the procedure for determining the intersection point of the radiation direction of the radar sensor of a motor vehicle with the measuring surface.

[0105] According to step 901, the measurement of the intensities of the radar beams at the measurement points of the measurement area can be used to determine whether the measured intensities at the measurement points exhibit only one local maximum or multiple local maxima. This step 901 corresponds to the first step in the method sequence of claim 2.

[0106] If this information about the properties of the radar sensor of the motor vehicle to be examined is already available, an identifier can be set according to step 902 to indicate whether only one radar beam is being emitted or whether multiple radar beams are being emitted. This corresponds to the procedure in connection with claim 3.

[0107] Subsequently, in step 903, it is checked whether there is only a local maximum of the intensities of the radar beams in the measuring points of the measuring area.

[0108] If this is the case, a transition takes place to step 904, in which the measuring point of the measuring surface in which the local maximum was determined is determined as the intersection point of the radiation direction of the radar sensor of the motor vehicle to be examined with the measuring surface.

[0109] If the check in step 903 reveals that multiple local maxima of the measured radar beam intensities are present at the measurement points of the measurement area, a center point for the measurement points of the measurement area at which the local maxima of the radar beam intensities were detected is determined in step 905. In this case, this center point is the intersection point of the radiation direction of the radar sensor of the motor vehicle under investigation with the measurement area.

[0110] The Fig. The method shown in Figure 9 can be carried out for different distances in the X-direction of the measuring surface from the radar sensor of the vehicle under investigation. This results in several of these intersection points of the radiation direction of the radar sensor of the vehicle under investigation with measuring surfaces at different positions in the X-direction. As in connection with Fig. As described in Section 8, the parameters of a regression line of the radiation direction of the radar sensor of a motor vehicle to be examined can be determined in the coordinate system of the vehicle test bench.

[0111] Fig. 10 shows an example of the procedure for checking whether the angle between the radiation direction of the radar sensor of the motor vehicle and the symmetry axis of the motor vehicle or the geometric driving axis of the motor vehicle lies outside a tolerance range for this angle.

[0112] According to step 1001, the parameters of the regression line of the radiation direction of the radar sensor of the motor vehicle are determined.

[0113] In step 1002, these parameters of the regression line, which are determined with respect to the symmetry axis of the motor vehicle or to the geometric driving axis of the motor vehicle in the coordinate system of the vehicle test bench, are compared with the tolerance range of the radiation direction of the radar sensor.

[0114] If the test in step 1002 shows that the measured radiation direction of the radar sensor is outside the tolerance range, a corresponding error signal is output in step 1003.

[0115] If the test in step 1002 shows that the radiation direction of the radar sensor lies within the specified tolerance range, the method is carried out according to Fig. 10 terminated without outputting the error signal.

Claims

[1] Method for measuring the orientation of the radiation direction of radar sensors in a motor vehicle, > wherein the motor vehicle is located in a vehicle test bench (301) for carrying out a test bench drive, ➢wherein the radar sensor emits radar beams and receives radar beams reflected from objects in the vicinity of the vehicle while the vehicle is in motion, ➢wherein the position and orientation of the motor vehicle is defined in a coordinate system of the vehicle test bench (301), characterized by , ➢that the position and orientation of at least one measuring surface (303) are defined in the coordinate system of the vehicle test bench (301), ➢that the measuring surface (303) is divided into several measuring points which are spaced apart horizontally and vertically, ➢that a sensor unit is provided with which the intensity of the radar beams emitted by the vehicle sensor is detected in one or more measuring points of the measuring area (303), ➢that the sensor unit - if the sensor unit does not record the intensity of the radar beams at all measuring points of the measuring surface (303) at one time - is adjustable in position (Y, Z) in the vehicle test bench (301) so that the intensity of the radar beams is recorded at several measuring points of the measuring surface (303), ➢that by comparing the measured intensities at the measuring points of the measuring surface (303) by evaluating symmetries in the measured intensities at the individual measuring points of the measuring surface (303), an intersection point of the radiation direction of the radar sensor of the motor vehicle located in the vehicle test bench with the measuring surface (303) is determined. [2] Method according to claim 1, characterized bythat for the measuring points of the measuring surface (303) it is determined whether a local maximum of the measured intensities of the radar beams in the measuring points exists only in one of the measuring points of the measuring surface (303) (901), > in this case, as a first alternative of the further method, the measuring point at which the maximum intensity of the radar beams was measured is determined as the intersection point of the radiation direction of the radar sensor of the motor vehicle located in the vehicle test bench with the measuring surface (904) and > Where several local maxima of the measured intensities of the radar beams are present in the measuring points of the measuring surface, as a second alternative of the further method, a center point for the measuring points with the local maxima of the intensities of the radar beams is determined as the intersection point of the radiation direction of the radar sensor of the motor vehicle located in the vehicle test bench with the measuring surface (303) (905). [3] Method according to claim 1, characterized by , ➢that when only one radar beam (radar lobe) is emitted by the radar sensor of the motor vehicle in the vehicle test bench, the first alternative of the method is to determine the measuring point at which the maximum intensity of the radar beams was measured, as the intersection point of the radiation direction of the radar sensor of the motor vehicle in the vehicle test bench with the measuring surface (904) and ➢that when several radar beams (radar lobes) are emitted by the radar sensor of the motor vehicle located in the vehicle test bench, as a second alternative of the method, the measuring points of the measuring surface are determined in which a local maximum of the measured intensity of the radar beams is present in the measuring points of the measuring surface, wherein a center point for the measuring points with the local maxima of the intensities of the radar beams is determined as the intersection point of the radiation direction of the radar sensor of the motor vehicle located in the vehicle test bench with the measuring surface (303) (905). [4] Method according to one of claims 1 to 3, characterized by that the measuring surface (303) is flat and that the surface normal of the measuring surface (303) extends in a direction that is parallel to the longitudinal direction (axis of symmetry) of the motor vehicle in the vehicle test bench (X). [5] Method according to one of claims 1 to 4, characterized bythat the distance of the measuring surface (303) from the motor vehicle located in the vehicle test bench can be adjusted to different values ​​(X). [6] Method according to claim 5, characterized by that at the intersection points of the radiation direction of the radar sensor of the motor vehicle located in the vehicle test bench with the measuring surfaces (303) adjusted to the different distances of the respective measuring surfaces (303) to the motor vehicle located in the vehicle test bench, a connecting line of the intersection points determined at the different distances (X1, X2, X3, X4) of the measuring surface is determined as part of a straight line on which the radar sensor is arranged. [7] Method according to claim 6, characterized bythat if a tolerance range for the angle between, on the one hand, the connecting line and, on the other hand, the axis of symmetry of the motor vehicle and / or the geometric driving axis of the motor vehicle (1002) is exceeded, an error signal is output (1003) for the adjustment of the radar sensor. [8] Method according to one of claims 1 to 7, characterized by that when carrying out a test bench drive, the radar sensor of the motor vehicle is stimulated, during which the parameters of the straight line to which the connecting line is a component are taken into account when positioning a radar target simulator and / or determining the radar beams emitted by the radar target simulator.

Images