Assembly and method for calibrating at least one radar sensor of a vehicle

Abstract

The invention relates to a method and an assembly (11) for calibrating at least one radar sensor (25) of a vehicle (30), the assembly (11) comprising a calibration device (1) which has: - a reflector plate (10) for reflecting radar radiation from the radar sensor (25), and - at least one camera (60), and the assembly (11) being designed to acquire orientation information relating to at least one of the vehicle (30), the radar sensor (25) and the reflector plate (10) on the basis of image information captured by the camera (60) and to generate, on the basis of this orientation information, control specifications for the actuator-based movement of the reflector plate (10).

Description

[0001] Hella Gutmann Solutions GmbH

[0002] P149541PC01 - Fully automated calibration of driver assistance system sensors

[0003] Arrangement and method for calibrating at least one radar sensor of a vehicle

[0004] The invention relates to an arrangement and a method for calibrating at least one radar sensor of a vehicle.

[0005] Driver assistance systems used in vehicles, and especially in road vehicles, often include a radar sensor. These are generally operated as distance measuring devices and measure the distance to a vehicle ahead or an obstacle in front of the vehicle in the direction of travel. Depending on the vehicle speed, these assistance systems can, for example, generate acoustic, visual, or tactile warning signals in case of danger and / or automatically apply the vehicle's brakes.

[0006] One example is an "Adaptive Cruise Control" (ACC) driver assistance system. This system supports the driver by automatically monitoring traffic, measuring the distance to vehicles ahead or obstacles in the roadway using a radar sensor, and regulating the vehicle's speed based on these measurements, for example, taking into account a preset safety distance. If this preset safety distance is breached, braking can be initiated automatically, or the speed can be reduced in another way, such as by automatically releasing the accelerator pedal.

[0007] Other examples of assistance systems include emergency brake assist, lane keeping assist, obstacle detection, traffic sign recognition, and autonomous vehicles (Level 1-5).

[0008] In connection with such assistance systems and with radar sensors in general, it is necessary to check, measure and, if necessary, correct the correct alignment of the radar sensor at regular intervals.

[0009] Otherwise, inaccurate measurement signals from the radar sensors can lead to inaccurate functioning of the assistance systems and thus endanger driving safety.

[0010] German patent DE 20 2015 106 939 Ul discloses a solution for calibrating radar sensors to ensure their correct alignment and thus their measurement accuracy. This includes, among other things, an angle-adjustable plate to which a ferromagnetic mounting plate carrying a laser can be attached if required. The angle adjustment is performed manually.

[0011] The required angular adjustment of such plates is usually specified by the vehicle manufacturer, and several successive angular adjustments with subsequent calibration measurements may be necessary within the calibration process of a radar sensor. It has been shown that existing solutions still offer potential for improvement regarding the achievable calibration accuracy and, consequently, the measurement accuracy of vehicle-mounted radar sensors.

[0012] Accordingly, the invention aims to further improve the calibration accuracy and thus the measurement accuracy of vehicle-mounted radar sensors.

[0013] This problem is solved by the subject matter of the attached independent claims. Advantageous embodiments are specified in this description, in the figures, and in the dependent claims.

[0014] Accordingly, an arrangement for calibrating at least one radar sensor of a vehicle is proposed, wherein the arrangement comprises a calibration device with:

[0015] • a reflector plate for reflecting radar radiation from the radar sensor, and

[0016] • at least one camera, wherein the arrangement is configured to determine, on the basis of image information captured by the camera, orientation information relating to at least one of the vehicle, the radar sensor and the reflector plate, and to generate control specifications for an actuator movement of the reflector plate.

[0017] A reflector plate of the type is distributed by the applicant as part of the so-called “Radar Kit 1 EVO”, however, this reflector plate can only be moved manually so far.

[0018] The reflector plate can be dropped against a surface and / or held at a defined distance from it using a holding frame of the calibration device.

[0019] The mounting frame can optionally be mounted on a chassis to allow it to be moved along the surface. The surface can be, in particular, a workshop floor and / or generally a flat surface. The mounting frame can extend upright relative to the surface, and in particular, in a spatially vertical direction. The mounting frame can be configured to support the reflector plate at a fixed or optionally variable distance relative to the surface. The mounting frame can generally be configured to position the reflector plate in front of a vehicle, and in particular at the height of the headlights and / or a bumper and / or a radiator grille, each corresponding to a typical installation height of radar sensors.

[0020] The determination of the alignment information and the generation of the control parameters can be performed in a control unit of the calibration device. Alternatively, this can be performed in a diagnostic device external to the calibration device. These measures, or individual steps thereof, can also be divided between the aforementioned control unit and the external diagnostic device, whereby the control unit and the external diagnostic device can communicate with each other. According to one embodiment, the arrangement may also include the external diagnostic device or be communicatively connected to it.

[0021] In this context, an orientation can generally be understood as a position and / or location (i.e., orientation). The orientation information can include at least one position value and / or location value. Preferably, however, the complete spatial orientation, i.e., the complete position and location, is determined as part of the orientation information, for example, with respect to a Cartesian spatial coordinate system. Additionally or alternatively, the orientation information can include relative orientations, in particular again comprising the complete relative position and location, between at least two of the vehicle, the radar sensor, and the reflector plate.

[0022] To determine the orientation information of at least one of the vehicle, the radar sensor, or the reflector plate, the camera can capture image information containing optically detectable target markers. These targets are located, for example, on the vehicle wheels, the radar sensor, a manufacturer's emblem, and / or the reflector plate. Based on the targets captured in the camera image, the spatial location and / or orientation (especially position and / or angular position) of the respective object can be determined by evaluation using known image processing methods—in particular, by utilizing geometric features or relative positioning of the targets and / or objects. The image information is evaluated, for example, by a control unit of the calibration device or, alternatively, by an external diagnostic device.In particular, the position coordinates of target markers can be analyzed to determine the absolute or relative orientation of the reflector plate, radar sensor and / or vehicle.

[0023] For example, the detected target positions can be used to determine a geometric driving axis of the vehicle, to which the reflector plate is aligned by appropriate movements (e.g., translation and / or tilting). The reflector plate can be moved so that it is aligned orthogonally to the vehicle's longitudinal axis or parallel to the vehicle's front. The distance to the vehicle's front or to defined reference points (e.g., the radar sensor) can also be determined from the image information and used to control the reflector plate's movement. The entire determination of the alignment information can be automated and / or performed using camera-based, algorithmically evaluated sensor data, thus ensuring precise and repeatable alignment.

[0024] Alternatively, the determination of orientation information can also be carried out without the use of special optical target markers. Instead, the camera can capture image-based information from freely visible features of the vehicle or its surroundings, which is then evaluated using suitable image processing and pattern recognition methods. For example, characteristic geometric structures, relative positions, or defined shape elements in the image are identified and used to derive the spatial position and / or orientation. Additionally, spatial triangulation can be performed by sequentially capturing images from different camera positions or viewing angles—for example, in a stereo or multi-view method—to determine, for instance, the camera's orientation relative to the vehicle.

[0025] Using the solution disclosed herein, the arrangement is independently capable of setting and, in particular, adjusting the reflector plate to a specific orientation required for precise calibration measurements, whether predetermined or otherwise. This preferably applies to both automatic translation of the reflector plate and automatic tilting or angular adjustment of the plate. The camera can detect the necessary adjustment movements, especially translational, rotational, and tilting movements, and preferably implement them automatically. Iterative and / or manual readjustments by an operator can be eliminated or significantly reduced. Consequently, the associated potential for errors can also be reduced. Overall, the degree of automation and, more generally, the accuracy of the calibration processes described herein can be increased.

[0026] The automated movements can involve both performing calibration measurements, e.g., by adjusting and varying the angles of the reflector plate, and preparing for these measurements. The latter can include movements to locate and adjust a predefined orientation of the reflector plate relative to the radar sensor.

[0027] Accordingly, further training stipulates that the arrangement is configured to set and, in particular, vary the angle, or angular position, of the reflector plate for performing a calibration measurement. The latter can involve a systematic and / or stepwise change of the angle to perform successive measurements for each angle. For setting and / or varying the angle, a tilting actuator, as described below, can be used, for example.

[0028] In this way, for example, manufacturer-defined calibration procedures or adaptively selected measurement strategies can be implemented precisely, and the overall calibration accuracy can be increased.

[0029] According to further training, the camera is stationary relative to the reflector plate. This can be understood to mean that the spatial position of the camera relative to the reflector plate, and especially to its geometric center, is unchanging. This can facilitate the determination of the spatial orientation of the reflector plate, particularly relative to the camera.

[0030] According to further training, the camera is positioned outside the reflector plate and / or designed to capture images of it. For example, from the vehicle's perspective, the camera can be located behind the reflector plate and / or capture at least part of its back surface. This reduces the need for modifications to existing reflector plate designs and / or simplifies retrofitting the camera to existing systems.

[0031] According to a further development, the arrangement also includes at least one tilting actuator configured to adjust the angular position of the reflector plate about at least one axis according to the control specifications. Like any other actuator disclosed herein, the tilting actuator can include an electric motor or a differently designed actuator, such as a hydraulic or pneumatic cylinder.

[0032] The control specifications can, in particular, serve to automatically set a suitable angular position or all spatial angular positions for carrying out the calibration measurement.

[0033] The tilting actuator can be encompassed by a tilting mechanism that includes at least one further tilting actuator for tilting the reflector plate along at least one additional axis. The resulting two tilting motion axes can be orthogonal to each other. A third tilting actuator can also be encompassed by the tilting mechanism to enable tilting around all spatial (tilting) degrees of freedom, and thus, in particular, around three mutually orthogonal tilting motion axes.

[0034] In one embodiment, the reflector plate can be tilted relative to the camera by means of the tilting actuator. The camera, on the other hand, can be characterized by a fixed spatial position. This can reduce the evaluation effort of the captured images and / or the overall system complexity of the calibration device.

[0035] The arrangement may, additionally or alternatively, include at least one displacement actuator configured to move the camera and / or the reflector plate along at least one axis. In general, the displacement actuator may be configured to transfer the reflector plate, while the tilt actuator may be configured to rotate the reflector plate.

[0036] The displacements can be used in particular for the automated setting of a suitable position or spatial coordinates of the reflector plate and especially its complete spatial coordinates for carrying out a calibration measurement.

[0037] According to one variant, the displacement actuator is encompassed by a linear displacement mechanism, which can include at least one further displacement actuator for moving the reflector plate and / or camera along at least one further axis. The two linear motion axes thus present can be orthogonal to each other. A third displacement actuator can also be encompassed by the linear displacement mechanism to enable a total displacement and all spatial linear degrees of freedom, i.e., in particular, three orthogonal linear motion axes.

[0038] According to one variant, the linear displacement mechanism and the tilting mechanism are designed separately from each other and / or can be controlled separately and / or each comprise their own actuators. In one embodiment, the tilting mechanism can be displaceable from the linear displacement mechanism. In another embodiment, the linear displacement mechanism can be tiltable and / or rotatable from the tilting mechanism.

[0039] According to one variant, the linear displacement mechanism and the tilting mechanism are at least partially integrated and / or implemented as a single, unified movement mechanism. For example, the reflector plate can be moved in all six spatial degrees of freedom by means of an articulated arm, and in particular a hinged arm. The articulated arm and hinged arm are examples of the aforementioned movement mechanism. The pivot joints of such an articulated arm or hinged arm can be understood as both displacement actuators and tilting actuators.

[0040] In one embodiment, the camera and the reflector plate can be moved together by means of the displacement actuator, in particular parallel to a surface and / or along an opposite side of the vehicle.

[0041] Independent movement of the camera and reflector plate, for example with individually assigned actuators, is also possible. For instance, the camera can be moved independently of the reflector plate into the first and second positions described below for detecting targets coupled to vehicle wheels.

[0042] The arrangement may optionally also include at least one target detectable by the camera, which can be attached to the vehicle and / or to the radar sensor.

[0043] According to further training, the control unit is also designed to determine at least one of the following pieces of information based on the image information:

[0044] • a vehicle manufacturer, for example by capturing a manufacturer's emblem;

[0045] • a vehicle type, for example by capturing predetermined features and in particular predetermined contours;

[0046] • a vehicle registration number;

[0047] • a geometric driving axis of the vehicle, for example by detecting the positions of vehicle wheels and especially wheel hubs at both ends of a vehicle axle;

[0048] • a distance between the reflector plate and the radar sensor.

[0049] The invention also relates to a method for calibrating at least one radar sensor of a vehicle by means of a reflector plate for reflecting radar radiation from the radar sensor, wherein the method comprises:

[0050] • Capturing image information using a camera;

[0051] • Determining alignment information regarding the vehicle and / or the radar sensor and / or the reflector plate based on the image information;

[0052] • Actuator-based movement of the reflector plate according to the alignment information.

[0053] In this case, too, the actuator movement is preferably automated, particularly with regard to both translation and rotation. Specifically, all movements of the reflector plate and the camera during calibration can be fully automated and actuated.

[0054] According to a further development, the actuator movement comprises tilting the reflector plate about at least one axis, and in particular about all three axes of a spatial Cartesian coordinate system. Specifically, the tilting can be performed by varying the position angle of the reflector plate to carry out a calibration measurement, and in particular by successively assuming several different position angles. At least one measurement operation can be carried out at each of the position angles.

[0055] According to further training, the actuator movement includes shifting the reflector plate along at least one axis and in particular around all three axes of a spatial Cartesian coordinate system.

[0056] According to a further development, the camera is moved between a first position and at least a second position to capture the image information. Specifically, in the first position, the camera captures image information from a first side of the vehicle and / or a target located there, and in the second position, it captures image information from a second side of the vehicle and / or a target located there. The target can be an optically detectable target according to any variant disclosed herein.

[0057] According to further training, at least one of the following pieces of information can also be determined from the image information:

[0058] • a vehicle manufacturer,

[0059] • a vehicle type,

[0060] • a vehicle registration number,

[0061] • a geometric driving axis of the vehicle,

[0062] • a distance between the reflector plate and the radar sensor.

[0063] All further embodiments and variants explained in the context of the device disclosed herein may also apply in the context of the method, and vice versa. This applies in particular to identical or comparable features. Exemplary embodiments of the invention are explained below with reference to the schematic figures.

[0064] Figure 1 shows a device according to an embodiment of the invention, which performs a method according to the invention, in a side view.

[0065] Figure 2 shows the device from Figure 1 in a frontal view.

[0066] Figure 3 shows a flowchart of a method according to the invention.

[0067] Figure 1 shows an arrangement 11 according to an embodiment of the invention. The arrangement 11 comprises a calibration device 1, which will be explained below, and optionally also a diagnostic device 100 (see Figure 2). The calibration device 1 is used to calibrate a radar sensor 25 in a partially depicted vehicle 30. The vehicle 30 is a motor vehicle, and in particular a road vehicle, such as a passenger car (shown) or a truck (not shown). The radar sensor 25 is mounted in the front of the vehicle, so that the calibration device 1 is oriented opposite and parallel to the front of the vehicle, and more precisely orthogonally to a longitudinal axis of the vehicle (not shown).

[0068] The disclosed solution is not limited to radar sensors 25 mounted in or near the front of the vehicle. This is merely an example, and radar sensors 25 installed in or near the rear of the vehicle can also be calibrated, for example.

[0069] The calibration device 1 comprises a mounting frame 2, the precise design of which is not restricted, and which stands upright on a base 3, in particular on a workshop floor. By way of example, the mounting frame 2 includes an optional chassis 4 to allow it to be moved relative to the vehicle 30. The mounting frame 2 carries an optional calibration target 5 in its upper section for calibrating vehicle camera sensors (not shown) using known techniques. The mounting frame 2 can also be designed without such a calibration target 5 and, in particular, serve solely for calibrating radar sensors 25.

[0070] For the latter purpose, the calibration device 1 comprises a reflector plate 10, which has a generally flat and, in particular, smooth surface. The reflector plate 10 faces the vehicle 30 in order to reflect radar radiation emanating from the radar sensor 25. With the exception of its actuator adjustability according to the invention, the reflector plate 10 corresponds to a prior art example.

[0071] Figure 1 shows a very schematic representation of the movable coupling 6 of the reflector plate 10 to the mounting frame 2. This movable coupling 6 allows the reflector plate 10 to be actively moved relative to the mounting frame 2 in all six spatial degrees of freedom. Details of this are explained below with reference to Figure 2.

[0072] Figure 2 shows a frontal view of the calibration device 1, for example from the perspective of the vehicle 30 and / or the radar sensor 25 from Figure 1. Only a part of the calibration target 5, which is generally optional, is shown and could also be omitted entirely.

[0073] The proportions in Figures 1 and 2, and especially when comparing these Figures 1 and 2, are schematically simplified with respect to the calibration device 1. For example, the size of the reflector plate 10 in Figure 2 is significantly exaggerated compared to Figure 1, although this size is not essential and can be chosen according to existing solutions. The distance between the reflector plate 10 and the base 3 also differs between Figures 1 and 2, without this being essential or generally limiting to the invention. In principle, this distance can be chosen arbitrarily and / or suitably adapted to the height of the radar sensor 25.

[0074] The movable coupling 6 comprises a tilting mechanism 40 by means of which the reflector plate 10 can be tilted according to all spatial degrees of freedom, and a linear displacement mechanism 50 by means of which the reflector plate 10 can be displaced or, in other words, translatable according to all spatial degrees of freedom.

[0075] In the example shown, the tilting mechanism 40 and the linear displacement mechanism 50 are designed as independently operable and / or independently controllable units. More precisely, the linear displacement mechanism 50 is configured to linearly displace the tilting mechanism 40, along with the reflector plate 10 coupled to it, in space, while the angular positions of the reflector plate 10 can be adjusted by means of the appropriately positioned tilting mechanism 40. A reverse configuration is also possible according to embodiments, in which the tilting mechanism 40 appropriately tilts the linear displacement mechanism 50 itself, while the appropriately tilted linear displacement mechanism 50 appropriately transposes the coupled and jointly tilted reflector plate 10.

[0076] Furthermore, integrated or combined linear displacement and tilting mechanisms are also possible, for example in the form of an articulated arm or articulated arm and / or a hexapod mechanism.

[0077] Three tilting actuators 14 are schematically indicated as components of the tilting mechanism 40. These are located on the rear side of the reflector plate 10, facing away from the viewer, as indicated by its dashed outlines. The indicated positions are merely examples. Other positions of the actuators 14 are also possible, in particular in a form that at least partially overlaps each other.

[0078] The reflector plate 10 is mounted centrally on a ball joint 16 and can be tilted in all spatial degrees of freedom by means of this joint, in particular about all axes of a Cartesian spatial coordinate system 100 indicated in Figure 2. In this system, one axis is vertically upright, i.e., aligned along the direction of the gravitational force.

[0079] The tilting actuators 14 are, for example, linear actuators that are connected off-center to the back of the reflector plate 10 and are configured to apply forces perpendicular to the plane of the plate. This preferably occurs in both a direction facing the viewer and a direction away from them. The movements of the tilting actuators 14, or the forces applied by them, can be coordinated such that the reflector plate 10 can assume any angular position, at least within defined angular ranges, about each of the axes of the coordinate system 100. An axis of inclination A and a yaw axis B, about which the reflector plate 10 can be tilted, are indicated by way of example.

[0080] The actuators 14 are preferably individually controllable, although this control can be coordinated as described. The actuators 14, as well as the displacement actuators described below, are, for example, electric motors or are pneumatically or hydraulically operated.

[0081] Exemplary and non-restrictive alternative variants for enabling the actuator-controlled tilting of the reflector plate 10 about all spatial axes include arranging the reflector plate 10 on a three-axis tilting module, or in other words: a three-axis tilting unit, a three-axis tilting table, or a three-axis tilting platform. These can, for example, be mounted below the reflector plate 10 and moved by actuators 14 to execute the corresponding tilting movements. A hexapod mechanism or articulated arm are also possible alternative variants.

[0082] The movable coupling 6 also includes a linear displacement mechanism 50, which is indicated very schematically by means of a coordinate system 52 showing the orientation of its axes of movement. The position of this coordinate system 52 is schematic and not restrictive. The linear displacement mechanism 50 can, for example, also be mounted on the rear of the reflector plate 10 and thus be largely concealed in a frontal view as in Figure 2.

[0083] In the example shown, the linear displacement mechanism 50 carries the tilting mechanism 40. The ball joint 16 is, for example, attached to a movement axis of the linear displacement mechanism 50, which is not shown separately.

[0084] It is schematically indicated that the linear displacement mechanism 50 enables the tilting mechanism 40 or the reflector plate 10 to be displaced along all spatial axes of the coordinate system 100. For this purpose, the linear displacement mechanism 50 can be configured, for example, as a two-dimensional motion slide and / or a two-dimensional motion table and / or a cross table, in particular each combined with an additional lifting axis. Such systems are known from CNC technology, coordinate measuring technology, or 3D printers, for example in the form of so-called gantry kinematics. The linear displacement mechanism 50 includes, by way of example, a displacement actuator (not shown separately) for each of its axes of motion. The configurations of the linear displacement mechanism 50 explained with reference to Fig. 2 are only an example. The linear displacement mechanism 50 can also be arranged differently and, for example,The entire support frame 2 can be carried and moved in space along all axes of the coordinate system 100. In this case, the movable coupling 6 comprises only the tilting mechanism 40.

[0085] The calibration device 1 further comprises a control unit 12, for example comprising at least one processor for implementing and / or executing calculations in the manner of a computer. The control unit 12 is connected to the actuators 14 via signal connections 13 for signal and, in particular, data transmission. This transmission can, in particular, be wired.

[0086] Additionally or alternatively, signal connections not shown separately may be provided to output corresponding control signals to the displacement actuators.

[0087] Overall, the control device 12 is thus configured to specify an orientation of the reflector plate 10 with respect to all six spatial degrees of freedom (three translational degrees along the axes of the coordinate system 100 shown and three rotational degrees around these axes).

[0088] The control unit 12 is further connected to an external diagnostic device 100, i.e., externally with respect to the calibration device 1. For this purpose, the control unit 12 and the diagnostic device 100 each comprise a communication interface 18, 18', for example, a WLAN (Wireless Local Area Network) or Bluetooth interface. Signal and, in particular, data transmission can be established between these via a wired or wireless communication connection 20. The diagnostic device 100 comprises, for example, at least one processor for implementing and / or executing computational steps in the manner of a computer.

[0089] According to an optional operating mode, the control unit 12 receives information from the diagnostic device 100 via the communication link 20, for example in the form of calibration parameters, concerning a spatial orientation of the reflector plate 10 to be set, in particular relative to the radar sensor 25. Subsequently, the control unit 12 controls at least one actuator 14 of the tilting mechanism 40 or at least one actuator of the linear displacement mechanism 50 via one of the signal links 13 to set the spatial positions and spatial orientation (i.e. the spatial orientation) of the reflector plate 10.

[0090] In addition to the described actuator-based mobility of the reflector plate 10, the solution disclosed here is characterized by a camera-based detection of the reflector plate 10's orientation. This enables, in particular, a kind of self-regulating alignment of the reflector plate 10. This allows the reflector plate 10 to be aligned additionally or alternatively to any alignment specifications received from the diagnostic device 10. For example, the camera-based detection can be used to verify and ensure whether a specified orientation is actually implemented.

[0091] Referring first to Figure 1, it is shown that the calibration device 1 also includes at least one camera 60. This camera is held by means of an optional support arm 62. The support arm 62 is arranged on the rear side near the reflector plate 10, and the camera 60 faces the rear side of the reflector plate 62. Consequently, the camera 60 is obscured in Figure 2. However, the support arm 62 is shown schematically in Figure 2, and its exemplary position relative to the reflector plate 10 is not restrictive.

[0092] The camera 60 and the support arm 62 are coupled to the linear displacement mechanism 50 in such a way that they can be moved together with the reflector plate 10 along the axis of movement 52. For example, the support arm 62 is attached to a kinematic link of the linear displacement mechanism 50 that is closest to the reflector plate 10, and to which the ball joint 16 is optionally also attached. The camera 60 is thus stationary relative to the reflector plate 10. On the other hand, the reflector plate 10 can be tilted relative to the camera 60 according to all degrees of freedom of the tilting mechanism 40.

[0093] The camera 60 is generally configured to capture optical targets 8 located within its schematically indicated detection range 64. The captured image files can be output for evaluation to the control unit 12 of the calibration device 1 or to another evaluation unit, for example, one specifically designed for the camera 60 (not shown). A signal line, particularly a wired one, provided for this purpose is not shown separately.

[0094] Figure 1 shows an optical target 8 attached to a vehicle wheel, and in particular to its wheel hub. Such optical targets 8 are already used in comparable calibration contexts and comprise optically detectable patterns from which the spatial orientation of the target and / or a geometric driving axis of the vehicle can be determined. Reference is made by way of example to the applicant's prior art disclosure DE 10 2015 112 368 A1.

[0095] In the solution shown, optical targets 8 are mounted on both sides of each vehicle wheel on one axle. The camera 60 is moved into suitable positions by means of the linear displacement mechanism 50 in order to detect the optical targets 8 mounted on both sides of the vehicle. In a manner known per se, a geometric driving axis of the vehicle 30 can thus be determined.

[0096] Another optical target 8 is attached, at least temporarily, to or near the radar sensor 25, in particular in a defined relative orientation to the radar sensor 25. A further optical target 8 is attached to the rear of the reflector plate 10.

[0097] The camera 60 can determine the spatial orientation of the reflector plate 10, the radar sensor 25, and the vehicle 30, or its geometric driving axis, and / or their relative orientations by detecting all of these optical targets 8. All of these orientations are examples of orientation information within the meaning of this disclosure.

[0098] Based on the information obtained in this way, the reflector plate 10 can, for example, be appropriately aligned relative to the geometric vehicle axis, in particular orthogonally to it. Suitable angular positions can be set for this purpose using the tilting mechanism 40.

[0099] Furthermore, distances and / or heights of the reflector plate 10, particularly relative to the radar sensor 25, can be adjusted using the optical targets 8 on the vehicle wheels and / or on the radar sensor 25. The linear displacement mechanism 50 can be appropriately controlled for this purpose. Existing distances can be determined, for example, based on the size of an optical target in a captured camera image. Height differences can be determined, especially if the camera position is known, from the position coordinates of a target in a captured image file.

[0100] The camera 60 can alternatively or additionally detect a license plate and / or a manufacturer's emblem of the vehicle 30 in order to determine, for example, a distance relative to the reflector plate 10, in addition to the optical targets 8.

[0101] With reference to Figure 3, a process flow according to an example of the invention is explained below.

[0102] Sl: The camera 60 is automatically positioned relative to the vehicle's center by means of the linear displacement mechanism 50 so that the license plate can be captured. This information is used for vehicle, manufacturer, and / or model identification. For this purpose, the control unit 12 can evaluate the captured image information itself or transmit it to the diagnostic device 100 for evaluation. Subsequently, the diagnostic device 100 can retrieve calibration parameters from an internal database or from a database accessible via a server, in particular regarding a relative alignment to be set between the reflector plate 10 and, for example, the radar sensor 25.

[0103] Alternatively or additionally, information for vehicle, manufacturer and / or model identification, e.g. again in the form of the license plate, can also be manually entered into the diagnostic device 100.

[0104] As a further preparatory measure, the optical targets 8 described below are attached to a vehicle axle or its wheels and / or to a manufacturer's emblem, the radar sensor or another manufacturer-specified reference point.

[0105] The user then activates the calibration process, in particular by means of a corresponding input, e.g. in the diagnostic device 100. Subsequently, the calibration process is carried out as follows and preferably completely automatically without further manual intervention.

[0106] S2: The reflector plate 10 together with the stationary camera 60 moves automatically to one of the two sides of the vehicle by means of the linear displacement mechanism 50, so that the optical target 8 attached to a vehicle wheel or a vehicle axle can be detected there.

[0107] S3: S2 is repeated on the second side of the vehicle, including automatic movement or translation of the camera 60 to the second side of the vehicle, followed by automatic determination of the geometric driving axis based on the optical targets 8 detected on both sides of the vehicle, e.g., in the control unit 12 or the diagnostic device 100. The position angle of the reflector plate 10 is then automatically adjusted by means of the tilting mechanism 40 so that the determined geometric driving axis is taken into account and / or a target orientation specified according to the calibration parameters determined in S1 is assumed.

[0108] In particular, the reflector plate 10 can be tilted such that it is aligned parallel to the front of the vehicle and / or orthogonal to a longitudinal axis of the vehicle, the latter being, for example, orthogonal to the determined driving axis.

[0109] S4: For automatically adjusting the correct distance between the

[0110] Reflector plate 10 and radar sensor 25, as specified by the calibration parameters determined in S1, can detect different manufacturer-specific reference points, and the camera 60 can be automatically moved for this purpose, if necessary, using the linear displacement mechanism 50. For example, these reference points can be an optical target 8 on the vehicle wheel, an optical target 8 temporarily attached to the bumper of the vehicle 30 or to or near the radar sensor 25, or the manufacturer's emblem of the vehicle 30. This was previously attached in step S1 as a preparatory measure.

[0111] The camera 60 is automatically moved by means of the linear displacement mechanism 50 until it locates the corresponding target 8 at the reference point. In other words, the camera 60 is automatically moved in a search mode until it detects the target 8. The spatial position and orientation of the target 8 can be determined from the image of the target 8 in the camera image using known image evaluation algorithms. If the target 8 is not directly attached to the radar sensor 25, the spatial position and orientation of the radar sensor 25 can be determined, for example, by the control unit 12 or the diagnostic device 100, based on a known relative position of the reference point and the radar sensor 25, encompassed, for example, by the initially obtained calibration parameters.

[0112] S5: Subsequently, the reflector plate 10 is automatically positioned at the correct distance by means of the linear displacement mechanism 50, based on the automatically determined spatial position and orientation of the radar sensor 25 relative to it. The required movements can in turn be determined by the control unit 12 or the diagnostic device 100. This also includes positioning at a predetermined height, as specified, for example, by the calibration parameters from S1 and, if necessary, defined and / or verifiable using one of the reference points below.

[0113] S6: This establishes a target alignment of reflector plate 10 and radar sensor

[0114] 25 fully automated under automatic and actuator execution of all movements required for this purpose, the calibration process is subsequently started automatically again by the diagnostic device 100 by means of an output of corresponding control specifications to the control unit 12.

[0115] S7: The calibration measurements of the radar sensor 25 are performed automatically, particularly when the reflector plate 10 is set to different tilting angles using the tilting mechanism 40 and according to the manufacturer's specifications. These tilting angles are also set automatically. Once a calibration measurement has been performed at each tilting angle, the calibration process of the radar sensor 25 is complete.

[0116] S8: If further sensors are to be calibrated, at least the

[0117] Steps 5-7 are repeated for each sensor. S9: The determined and / or set alignment parameters, in particular those of the reflector plate 10 and / or the geometric driving axis, are recorded together with the calibration result by the diagnostic device 100 in a calibration protocol. Such a calibration protocol can comprise or form a data set or a general digital information collection that is linked to the calibration process and / or the underlying vehicle, for example, via a database. In this way, the execution of the calibration process can be tracked at a later time, and any potential errors can be identified automatically or manually.

[0118] It should be noted that all of the preceding procedural steps can be carried out fully automatically. An operator can optionally perform an initial rough positioning of the calibration device 1 relative to the vehicle 30 and can then start the automated calibration process by entering a value into the diagnostic device 100.

[0119] The automated measures include both finding and setting a target relative alignment of reflector plate 10 and radar sensor 25, as well as subsequently performing calibration measurements, whereby all necessary movements of reflector plate 10 and camera 60 are implemented automatically. Therefore, the calibration process can be described as fully automated.

Claims

1. Arrangement (11) for calibrating at least one radar sensor (25) of a vehicle (30), wherein the arrangement (11) comprises a calibration device (1), comprising: • a reflector plate (10) for reflecting radar radiation from the radar sensor (25), and • at least one camera (60), wherein the arrangement (11) is configured to determine, on the basis of image information acquired by the camera (60), orientation information relating to at least one of the vehicle (30), the radar sensor (25) and the reflector plate (10), and to generate control specifications for an actuator movement of the reflector plate (10).

2. Arrangement (11) according to claim 1, wherein the camera (60) is stationary relative to the reflector plate (10).

3. Arrangement (11) according to claim 1 or 2, wherein the camera (60) is arranged outside the reflector plate (10) and / or is configured to detect the same.

4. Arrangement (11) according to claim 3, wherein the camera (60) is arranged from the vehicle view rearward of the reflector plate (10) and / or captures at least a part of the rear of the reflector plate (10).

5. Arrangement (11) according to one of the preceding claims, wherein the arrangement (11) is configured to vary a position angle of the reflector plate (10) for performing a calibration measurement, in particular such that several different position angles are assumed successively.

6. Arrangement (11) according to one of the preceding claims, further comprising at least one tilting actuator (14) which is equipped to The task is to set an angular position of the reflector plate (10) about at least one axis (A, B) according to the control specifications.

7. Arrangement (11) according to claim 6, wherein the reflector plate (10) can be tilted relative to the camera (60) by means of the tilting actuator (14).

8. Arrangement (11) according to one of the preceding claims, further comprising at least one displacement actuator configured to displace the camera (60) and / or the reflector plate (10) along at least one axis (52).

9. Arrangement (11) according to one of the preceding claims, wherein the camera (60) and the reflector plate (10) are jointly displaceable by means of the displacement actuator, in particular parallel to a substrate (3) and / or along an opposite vehicle area.

10. Arrangement (11) according to one of the preceding claims, further comprising: at least one target (8) detectable by the camera (60) which can be attached to the vehicle (30) and / or to the radar sensor (25).

11. Arrangement (11) according to one of the preceding claims, wherein the arrangement (11) is configured to move the camera (60) in a search mode until it detects the target (8).

12. Arrangement (11) according to one of the preceding claims, wherein the control device (12) is further configured to determine at least one of the following pieces of information based on the image information: • a vehicle manufacturer, • a vehicle type, • a vehicle registration number, • a geometric driving axis of the vehicle (30), a distance between the reflector plate (10) and the radar sensor (25).

13. Method for calibrating at least one radar sensor (25) of a vehicle (30) by means of a reflector plate (10) for reflecting radar radiation from the radar sensor (25), wherein the method comprises: • Capturing image information using a camera (60), • Determining orientation information concerning the vehicle (30) and / or the radar sensor (25) and / or the reflector plate (10) based on the image information; • Actuator-based movement of the reflector plate (10) according to the alignment information.

14. Method according to claim 13, wherein the actuating movement comprises tilting the reflector plate (10) about at least one axis (A, B).

15. Method according to claim 14, wherein the tilting is carried out in such a way that a position angle of the reflector plate (10) is varied to perform a calibration measurement, in particular such that several different position angles are taken successively.

16. Method according to claim 13, 14 or 15, wherein the actuating movement comprises a displacement of the reflector plate (10) along at least one axis (52).

17. Method according to any one of claims 12 to 16, wherein the camera (60) is moved between a first position and at least a second position to capture the image information.

18. Method according to claim 17, wherein the camera (60) in the first position captures image information from a first side of the vehicle and / or a target (8) arranged therein, and in the second position captures image information from a second side of the vehicle and / or a target located there (8).

19. Method according to any one of claims 12 to 18, wherein at least one of the following pieces of information is also determined from the image information: • a vehicle manufacturer, • a vehicle type, • a vehicle registration number, • a geometric driving axis of the vehicle (30), • a distance between the reflector plate (10) and the radar sensor (25).

20. Method according to any one of claims 12 to 19, wherein at least one target (8) detectable by the camera (60) is attached to the vehicle (30) and / or to the radar sensor (25) and the method comprises: performing a search operation in which the camera (60) is moved until it detects the target (8).

Images