Method for determining at least one elevation variable of an object target using an automotive radar system

Abstract

The present invention relates to a method for determining at least one elevation variable (Θ, h) of an object target (22) of an object (18) detected in particular by a radar system (14) of a vehicle (10) relative to an elevation reference plane (31). The present invention further relates to a radar system and a vehicle having at least one radar system. In this method, a radar signal is radiated using at least one antenna of the radar system and echo signals of the radar signal reflected by the object target are received by at least two antennas. The phase centers of each of the antennas are arranged along a lower antenna axis extending parallel to the elevation reference plane (31). The speed of movement (V) of the radar system is determined by the following equation: H ) is determined. A radial velocity of at least one object target relative to the radar system is determined using the radar system by the echo signals. A first directional variable (α) characterizing the orientation of the object target relative to a first reference axis (y) fixed relative to the radar system is determined using the radar system by the received echo signals. A second directional variable (β) characterizing the orientation of the object target relative to a second reference axis (x) fixed relative to the radar system is determined using the radar system by the received echo signals. R ), and movement speed (V H At least one elevation parameter (Θ, a) ​​of the object target (22) is determined by at least one of the orientation parameters (α, β).

Description

[Technical field]

[0001] The present invention relates to a method for determining at least one elevation variable of an object target detected by a radar system, in particular a radar system of a vehicle, relative to an elevation reference plane, Using a radar system to emit a radar signal and receive an echo signal from the radar signal reflected by an object target; Determining the speed of movement of the radar system; A radial velocity of at least one object target relative to the radar system is determined using the radar system from the received echo signals; a first directional variable characterizing a direction of the object target relative to a first reference region fixed relative to the radar system is determined using the radar system from the received echo signals; a second directional variable characterizing a direction of the object target relative to a second reference region fixed relative to the radar system is determined by the first directional variable, the radial velocity, and the movement velocity; At least one elevation variable of the object target is determined by at least one of the orientation variables.

[0002] Furthermore, the present invention relates to radar systems, especially for vehicles, at least one antenna for emitting a radar signal; at least one antenna for receiving an echo signal of the radar signal reflected by an object target; means for determining at least one elevation variable from an object target detected using a radar system relative to an elevation reference plane, said means comprising: The means includes means for determining the radial velocity of a detected object target relative to the radar system from the received echo signals; means for determining, from the received echo signals, a first directional parameter characterizing the orientation of the object target relative to a first reference region fixed relative to the radar system; means for determining a second directional variable characterizing a direction of the object target relative to a second reference region fixed relative to the radar system, the second directional variable being determined by the first directional variable, the radial velocity, and the moving velocity of the radar system; The system includes a means for determining at least one elevation variable of the object target according to at least one of the orientation variables.

[0003] Furthermore, the present invention relates to a vehicle comprising at least one radar system, At least one radar system at least one antenna for emitting a radar signal; at least one antenna for receiving an echo signal of the radar signal reflected by an object target; means for determining at least one elevation variable from an object target detected using a radar system relative to an elevation reference plane, said means comprising: The means includes means for determining the radial velocity of a detected object target relative to the radar system from the received echo signals; means for determining, from the received echo signals, a first directional parameter characterizing the orientation of the object target relative to a first reference region fixed relative to the radar system; means for determining a second directional variable characterizing a direction of the object target relative to a second reference region fixed relative to the radar system, the second directional variable being determined by the first directional variable, the radial velocity, and the moving velocity of the radar system; The system includes a means for determining at least one elevation variable of the object target according to at least one of the orientation variables. [Background technology]

[0004] A method for radar-based measurement and / or classification of objects in a vehicle environment is known from DE 102018000517 A1, in which the vehicle environment is detected by at least one radar sensor arranged on the vehicle, and an item of Doppler information is generated during the determination and / or classification of the height of the object based on an evaluation of the shift in Doppler frequency between the radar signal emitted by the radar sensor and the radar signal reflected by the object. Assuming that an item of accurate movement information of the vehicle is available, the height of the object can be determined in that already determined information on the azimuth angle of the object is utilized together with the received Doppler information to accurately calculate the elevation angle. The azimuth angle of the object is determined by digital beamforming at multiple horizontal antennas of the radar sensor. If the elevation angle of the object has been calculated once, the height of the object can be determined from the elevation angle of the object and the radial distance from the radar sensor to the object, as defined in the formula:

[0005] The invention is based on the object of designing a method, a radar system and a vehicle of the kind mentioned in the introduction, which allows a more efficient implementation of the determination of at least one elevation variable of a detected object target relative to an elevation reference plane. In particular, the at least one elevation variable should be more accurate and / or easier to determine, in particular using simpler and / or space-saving means. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] DE 102018000517 Summary of the Invention

[0007] The object is according to the invention for the method The radar signal is radiated using at least one antenna of the radar system and the echo signal is received using at least two antennas of the radar system, the phase centers of each of the antennas being disposed along a virtual antenna axis extending parallel to an elevation reference plane; The first directional variable is determined relative to a first reference axis fixed relative to the radar system as a reference region, and the second directional variable is determined relative to a second reference axis fixed relative to the radar system as a reference region.

[0008] According to the invention, radar signals are transmitted and received using an antenna whose phase center is located along the antenna axis. The antenna axis extends parallel to the elevation reference plane. In this way, the antenna arrangement of the radar system can be constructed simply, space-saving and linearly. The arrangement of the antenna parallel to the elevation reference plane simplifies the assignment of directional variables.

[0009] According to the invention, the first and second directional variables are each determined relative to an associated reference axis. The directional variables can therefore be determined using a one-dimensional linear antenna arrangement. For this purpose, a two-dimensional planar antenna arrangement is not required. A two-dimensional planar antenna arrangement is required in order to be able to determine at least one elevation variable directly relative to an elevation reference plane. The invention makes it possible to determine at least one elevation variable relative to an elevation reference plane of an object target using a space-saving and simply designed linear antenna arrangement.

[0010] The elevation reference plane extends horizontally in a normal direction to the radar system, in particular to the vehicle. The azimuth angles lie in a plane extending parallel to the elevation reference plane, or as it is known, the elevation reference plane. The azimuth reference plane, in which the azimuth angles are defined, is perpendicular to the elevation reference plane.

[0011] The radial velocity of the object target is the relative velocity between the object target and the radar system in the direction of an imaginary connecting axis between the object target and a reference point of the radar system, which can advantageously be the intersection of at least two reference axes.

[0012] The reference point, in particular the intersection of at least two reference axes or the projection of the reference point in a direction perpendicular to the elevation reference plane, may advantageously be between the phase centers of the antennas, in particular on a virtual antenna axis of the radar system.

[0013] The reference point, in particular the intersection of the at least two reference axes, can advantageously be located on a plane defined by the contact areas of the wheels of the vehicle on the ground, in this way the reference system with the reference axes for the directional variables can be oriented on the roadway of the vehicle.

[0014] The movement speed of the radar system is the speed at which the radar system moves through space. The movement speed of the radar system may advantageously be the movement speed of a vehicle. The movement speed may be designated as ground speed or the like. The movement speed may advantageously be determined in particular using a speed measurement system of the vehicle.

[0015] The method is used to determine at least one elevation variable of the object target relative to an elevation reference plane. The elevation variable may advantageously be an elevation height. Alternatively or additionally, the elevation variable may be an elevation angle. The elevation height is the distance between the object target and the elevation reference plane. The elevation angle is the angle between an imaginary connection axis between the object target and a reference point of the radar system on the one hand and the elevation reference plane on the other hand.

[0016] Additionally, the method may be used to determine the azimuth angle of the object target. In this manner, the method may be used to more accurately determine both the at least one elevation variable and the azimuth angle.

[0017] When used in combination with a vehicle, the present invention can be used to determine the elevation angle height of an object target located in front of the vehicle in the direction of travel. If the elevation angle height is known, the driver assistance system of the vehicle can be used to determine whether the object target is located low enough for the vehicle to drive over it, or high enough for the vehicle to drive under it.

[0018] Typically, only the azimuth angle of a detected object target can be determined using a radar system having only a linear arrangement of multiple antennas, in particular radiating and receiving antennas. The azimuth angle can be assumed here based on the phase shift of the echo signal. The echo signals are detected here using different receiving antennas. The azimuth angle can be accurately determined using such a radar system only if the object target has the same elevation height as the phase center of the antenna, in particular the receiving antenna. If the object target is located at a different elevation height than the antenna, the azimuth angle is determined inaccurately. In order to be able to accurately determine both the azimuth and elevation variables, a configuration of radiating and receiving antennas arranged in a plane is usually used. In this case, additional radiating and receiving channels are required, with which the determination of the elevation variable is carried out exclusively. This increases the complexity and cost expenditure of the radar system used, which can be omitted in the present invention.

[0019] Using the method according to the invention and the radar system according to the invention, the distance and the direction of an object target relative to the radar system, in particular relative to a vehicle, can be determined in a two-dimensional plane. The object target can be characterized in three-dimensional space by accurate determination of at least one elevation variable. Overall, the invention makes it possible to create a complete three-dimensional map of the environment of the radar system, in particular of the vehicle. The invention makes it possible to improve both the determination of the azimuth angle and the determination of at least one elevation variable using a one-dimensional linear antenna arrangement, without additional antennas, in particular receiving antennas, arranged in a particular plane, being required for this purpose.

[0020] The radar system can be advantageously used in vehicles, in particular automobiles. The radar system can be advantageously used in land vehicles, in particular passenger cars, trucks, buses, motorcycles, aircraft, in particular drones, and / or marine vessels. The radar system can also be used in vehicles that can operate autonomously or at least semi-autonomously. However, the radar system is not limited to vehicles. It can also be used in stationary operations, robotics, and / or machines, in particular construction or transport machines, such as cranes, excavators, etc.

[0021] The radar system can be advantageously connected to or be part of at least one electronic control device of the vehicle or machine, in particular a driver assistance system and / or a chassis control system and / or a driver information device and / or a parking assistance system and / or a gesture recognition system, etc. In this way, at least some of the functions of the vehicle or machine can be performed autonomously or semi-autonomously.

[0022] In an advantageous design of the method, the first directional variable can be determined from a phase shift between echo signals of the same radar signal received using various antennas, thus allowing a more accurate determination of the first directional variable.

[0023] In one advantageous embodiment of the method, the second direction variable can be calculated from mathematical, in particular trigonometric, relations using the first direction variable, the radial speed and the movement speed, in particular the second direction variable in the form of a second direction angle, as the arcsine of the quotient of the radial speed and the product of the movement speed and the cosine of the first direction variable in the form of the first direction angle. In this way, the second direction variable can be calculated more accurately from the already determined variables, in particular the first direction variable, the radial speed and the movement speed. Thus, the second direction variable can be determined more accurately and individually. For this purpose, a corresponding conversion table is not required.

[0024] The second direction variable can advantageously be calculated in the form of a second direction angle as the arcsine of the quotient of the radial velocities and the product of the movement velocity and the cosine of the first direction variable in the form of the first direction angle. In this way, the direction variable can be calculated directly in the form of a direction angle.

[0025] The second direction angle can advantageously be calculated according to the following formula:

number

[0026] The at least one conversion table can be determined in advance, in particular in the course of calibration of the radar system, in particular at the end of a production line of the radar system or, as the case may be, the vehicle, and can be stored in a corresponding storage medium of the radar system, in particular in the control and evaluation device.

[0027] Advantageously, a conversion table can be provided for each different travel speed, the conversion table comprising for each travel speed a relationship between the first direction variable, the second direction variable and the radial speed, in this way an appropriate conversion table can be used depending on the respective travel speed.

[0028] The conversion table may advantageously comprise a number of triples, each having a first direction variable, a radial velocity and a corresponding second direction variable, the triples being particularly easy to store, particularly in software.

[0029] In a further advantageous embodiment of the method, the first and second directional variables can be implemented in the form of angles, in this way at least one elevation variable and / or azimuth angle of the detected object target can be more easily determined.

[0030] In a further advantageous embodiment of the method, the two reference axes can be specified to span a plane extending parallel to or in the elevation reference plane. In this way, the reference system for the direction variable and the reference system for the at least one elevation variable and the azimuth angle can have a common orientation. Thus, the at least one elevation variable and / or the azimuth angle can be more easily determined from the direction variable.

[0031] In a further advantageous embodiment, before the determination of the second direction variable, it can be checked whether the detected object target is stationary, and if the object target is not stationary, the method for determining at least one elevation variable of this object target can be terminated, otherwise the method for determining at least one elevation variable can be continued. In this way, only stationary object targets are used to determine at least one elevation variable. At least one elevation variable can be determined more accurately using stationary object targets.

[0032] Once terminated, the method for determining at least one elevation variable of an object target may advantageously be started again using another object target.

[0033] In a further advantageous embodiment of the method, in order to check whether the object target is stationary, it is possible to calculate the difference between the radial velocity and the product of the movement velocity and the cosine of the first directional variable, The difference can be compared to at least one limit value, and depending on the result of the comparison, it can be assumed that the object target is stationary and the method for determining the at least one elevation angle variable can be continued, otherwise the method can be terminated for this object target; and / or The difference can be compared to two specified limit values, and if the difference is between the two limit values, the object target can be assumed to be stationary and the method for determining at least one elevation variable can be continued, otherwise the method can be terminated for this object target. In this way, the velocity of the object target in space can be determined mathematically, in particular by trigonometry, taking into account the translation velocity, the radial velocity and the first directional variable.

[0034] The difference between the radial velocity and the product of the movement velocity and the cosine of the first direction variable can be advantageously compared with at least one limit value, and depending on the result of the comparison, it can be assumed that the object target is stationary. Here, if the difference is less than or equal to the limit value, it can be assumed that the object target is stationary. Alternatively or additionally, if the difference is greater than or equal to the limit value, it can be assumed that the object target is stationary.

[0035] The two limit values ​​can advantageously have different signs. In this way, a movement of the object target in a direction towards the radar system can be provided with a limit value having a different sign than a movement of the object target away from the radar system. The two limit values ​​can be specified so that the possible movement of the detected object target can be determined within the tolerances, in particular the measurement tolerances and / or the movement speed tolerances of the radar system.

[0036] In a further advantageous embodiment of the method, the at least one elevation variable and / or the azimuth angle of the object target can be calculated by the first direction variable and the second direction variable and / or can be obtained from at least one conversion table, in this way the determined direction variable can be converted with less effort into the at least one elevation variable and / or the azimuth angle.

[0037] At least one elevation variable and / or azimuth angle of the object target can be advantageously calculated from the first and second directional variables. Mathematical, in particular trigonometric, relationships can be used for this purpose.

[0038] Calculation of the elevation height as an elevation variable can be performed according to the following formula:

number

[0039] The range of the object target can be advantageously determined using a radar system, such that all variables related to the object target and necessary to determine at least one elevation variable can be determined using a single radar measurement.

[0040] Alternatively or additionally, the at least one elevation variable and / or the azimuth angle can be obtained from at least one conversion table. In this way, the at least one elevation variable and / or the azimuth angle can be determined faster without additional computational effort.

[0041] The triples with the possible elevation angle variables and the respective first and second direction variables can advantageously be stored in at least one conversion table, which can be predetermined, in particular in the course of calibration of the radar system, in particular at the end of a production line of the radar system, and can be stored in a corresponding storage medium of the radar system.

[0042] Further, according to the present invention, in a radar system, The radar system includes at least one antenna that can be used to radiate a radar signal and at least two antennas that can be used to receive echo signals from the radar signal reflected by an object target, the phase centers of each of the antennas being disposed along a virtual antenna axis that extends parallel to an elevation reference plane; The objective is achieved by having a first reference axis fixed as a reference region for a first directional variable relative to the radar system and a second reference axis fixed as a reference region for a second directional variable.

[0043] According to the invention, the antennas of the radar system are arranged linearly along a virtual antenna axis. In this way, the antenna arrangement can be designed space-saving and simply. Furthermore, the antenna arrangement can be oriented in a defined manner with respect to the elevation reference plane. Thus, at least one elevation variable can be more easily determined. The radar system has a fixed first reference axis and a fixed second reference axis, which are used as reference regions for the first and second directional variables.

[0044] Further, according to the present invention, in a vehicle, At least one radar system includes at least one antenna that can be used to radiate radar signals and at least two antennas that can be used to receive echo signals from the radar signals reflected by object targets, the phase centers of each of the antennas being disposed along a virtual antenna axis that extends parallel to an elevation reference plane; The objective is achieved by having at least one radar system have a first reference axis fixed as a reference region for a first directional variable and a second reference axis fixed as a reference region for a second directional variable.

[0045] Advantageously, at least one of the reference axes can be aligned in the direction of at least one defined imaginary axis of the vehicle, in particular the longitudinal axis, the transverse axis and / or the vertical axis and / or the axis of the direction of movement of the vehicle, in this way the items of information obtained using the at least one radar system can be more easily utilized as items of environmental information of the vehicle.

[0046] The vehicle may advantageously comprise at least one driver assistance system, with the aid of which the vehicle may operate autonomously or semi-autonomously.

[0047] The at least one radar system can advantageously be functionally connected to at least one driver assistance system, such that items of information about the environment of the vehicle acquired using the at least one radar system can be used by the at least one driver assistance system for autonomous or semi-autonomous operation of the vehicle.

[0048] At least one radar system can advantageously be an integral component, in particular, of a driver assistance system and / or an automated driving system of a vehicle. Radar systems have the advantage that the radial velocity of a detected object target can be determined directly using them.

[0049] Furthermore, the features and advantages given in connection with the method according to the invention, the radar system according to the invention and the vehicle according to the invention and their respective advantageous embodiments apply here in a mutually corresponding manner and vice versa, the individual features and advantages can of course be combined with one another and further advantageous effects may result which exceed the sum of the individual effects. [Brief description of the drawings]

[0050] Further advantages, features and details of the invention will become apparent from the following description, in which exemplary embodiments of the invention are described in more detail with reference to the drawings. The skilled person will also find it convenient to consider individually the features disclosed in combination in the drawings, the description and the claims, and combine them to form meaningful further combinations. In the schematic diagram: [Figure 1] 1 shows a front view of a vehicle having a radar system for monitoring a surveillance area ahead of the vehicle in the direction of travel, a driver assistance system and the measurement system described. [Diagram 2]FIG. 2 shows a three-dimensional representation of the driving situation of the vehicle of FIG. 1 with an object in front of the vehicle and a Cartesian coordinate system fixed relative to the radar system, the vehicle being shown only in a side view and not in a perspective view. [Diagram 3] 2 shows a front view of the antenna arrangement of the radar system of FIG. 1 with the control and evaluation device, the driver assistance system and the speed measurement system; [Figure 4] 3 shows a three-dimensional representation of the Cartesian coordinate system of FIG. 2 from different perspectives relative to a spherical representation. [Diagram 5] 4 shows a conversion table for determining a second direction angle of an object target from a first direction angle and a radial velocity of the object target. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0051] In the drawings, the same elements are given the same reference numerals.

[0052] 1 shows a front view of a vehicle 10 in the form of a passenger car. The vehicle 10 comprises a driver assistance system 12, a speed measurement system 34 and a radar system 14. The radar system 14 is functionally connected to the driver assistance system 12 and is able to transmit to the driver assistance system 12 items of information obtained using the radar system 14 via a monitoring area 16 ahead of the direction of travel of the vehicle 10. Functions of the vehicle 10, for example driving functions, can be performed autonomously or semi-autonomously using the driver assistance system 12.

[0053] Radar system 14 is illustratively located on the front fender of vehicle 10 and pointed into surveillance area 16. Radar system 14 may also be located at different points on vehicle 10 and may be oriented in different directions.

[0054] Objects 18 within the monitored area 16 may be detected using the radar system 14 .

[0055] The objects 18 may be stationary or moving objects, such as vehicles, people, animals, plants, obstacles, road irregularities such as potholes or stones, road boundaries, traffic signs, open spaces such as parking spaces, rainfall, etc.

[0056] A radar signal 20 is emitted into the surveillance area 16 using the radar system 14 to detect an object 18. The radar signal 20 reflected by an object target 22 of the object 18 in the direction of the radar system 14 is received as an echo signal 24 using the radar system 14. Object information, such as range R, radial velocity V, R Elevation variables such as elevation angle Θ and elevation height h, as well as the azimuth angle of each object target 22 relative to the reference region of the radar system 14 and therefore relative to the vehicle 10 can be determined from the received echo signals 24.

[0057] An object target 22 is an area of ​​the object 18 capable of reflecting the radar signal 20. The object 18 may have one or more such object targets 22. If the object 18 has multiple object targets 22, the radar signal 20 may also be reflected thereon differently, e.g., in different directions.

[0058] 1 to 4 show the corresponding coordinate axes of a Cartesian xyz coordinate system. Figs. 2 and 4 show the xyz coordinate system in a three-dimensional representation. The x-axis of the xyz coordinate system extends parallel to the longitudinal axis of the vehicle 10 along a plane below the vehicle 10, which extends to the operating position of the vehicle 10 by the tire contact patch, for example. The y-axis extends to the left in the direction of travel, parallel to the transverse axis of the vehicle 10. The z-axis extends spatially upwards, parallel to the vertical axis of the vehicle 10. The projection of the coordinate origin 26 of the xyz coordinate system in the z-axis direction lies between the emitting antenna Tx and the receiving antenna Rx of the radar system 14. The coordinate origin 26 forms a fixed reference point of the radar system 14.

[0059] The phase center 28 of each of the radiating antenna Tx and the receiving antenna Rx is disposed on a virtual antenna axis 30, as shown in Figure 3. The antenna axis 30 is parallel to the y-axis and parallel to the xy-plane of the xyz coordinate system.

[0060] The xy plane of the xyz coordinate system is the elevation reference plane 31 of the radar system 14. The xz plane of the xyz coordinate system is the azimuth reference plane 33 of the radar system 14. The azimuth reference plane 33 is perpendicular to the elevation reference plane 31.

[0061] The radar system 14 has three receiving antennas Rx and one radiating antenna Tx, as shown in Fig. 3. Fig. 3 shows the radiating antennas Tx and the receiving antennas Rx in a front view, as seen in the x-axis direction from the monitoring area 16. The receiving antennas Rx and the radiating antennas Tx are functionally connected to a control and evaluation device 32 of the radar system 14. The control and evaluation device 32 is shown as an example above the radiating antennas Tx and the receiving antennas Rx for better clarity. It can also be located at another point. Furthermore, the driver assistance system 12 and the speed measurement system 34 are shown in Fig. 3.

[0062] The radiating antenna Tx may be operated to radiate the radar signal 20 using a control and evaluation unit 32. The echo signal 24 may be received using a receiving antenna Rx and converted into an electrical signal. The electrical signal may be transmitted to the control and evaluation unit 32 and processed. For example, items of object information relating to the detected object 18 may be determined from the electrical signal.

[0063] The control and evaluation device 32 is connected to the driver assistance system 12. Items of information determined using the control and evaluation device 32, such as items of object information relating to detected objects 18, can be transmitted to the driver assistance system 12 via the connection. The transmitted items of information can be used by the driver assistance system 12 for autonomous or semi-autonomous operation of the vehicle 10.

[0064] Vehicle 10 movement speed V H can be determined using a speed measurement system 34, which is for example connected to the control and evaluation device 32. The determined travel speed V Hdirectly to the radar system 14. The speed measurement system 34 can also be indirectly connected to the radar system 14 and / or the driver assistance system 12, for example via a control unit of the vehicle 10.

[0065] The orientation of a detected object target 22 relative to the radar system 14 is characterized by elevation variables in the form of an azimuth angle Φ and an elevation angle Θ. The azimuth angle Φ and elevation angle Θ of the object target 22 of the object 18 are shown in Figure 4, which illustrates the coordinate system 26 with a spherical representation for ease of understanding.

[0066] The azimuth angle Φ is the angle between the azimuth reference plane 33 and the orthogonal projection of the connecting axis between the object target 22 and the coordinate origin 26 on the elevation reference plane 31. The elevation angle Θ is the angle between the elevation reference plane 31 and the connecting axis of the object target 22 with the coordinate origin 26. The azimuth angle Φ and the elevation angle Θ characterize the orientation of the object target 22 with respect to the respective reference planes, i.e. the elevation reference plane 31 and the azimuth reference plane 33.

[0067] The direction of a detected object target 22 can be determined using the radar system 14 from measurements of the phase difference of the received echo signals 24 between the three receiving antennas Rx. Due to the linear arrangement of the receiving antennas Rx, a first directional variable in the form of a first directional angle α can be determined from the phase difference.

[0068] The first direction angle α is the angle between the x-axis and the connecting axis between the detected object target 22 and the coordinate origin 26. The x-axis is a fixed first reference axis of the radar system 14 for the first direction angle α. The first direction angle α corresponds to the azimuth angle Φ only if the detected object target 22 is in the elevation reference plane 31, i.e. at the same elevation height h as the radar system 14.

[0069] The elevation height h is the height above, and therefore the distance to, the elevation reference plane 31. The elevation height h and the elevation angle Θ are each elevation variables that also characterize the position of the object target 22.

[0070] A second directional variable in the form of a second directional angle β is determined by the first directional angle α, the radial velocity V R , and the range R of the detected object target 22.

[0071] The range R is the distance of the detected object target 22 to the reference point of the radar system 14, i.e., the coordinate origin 26. The second direction angle β is the angle between the y-axis and the connecting axis between the object target 22 and the coordinate origin 26. The y-axis is a second fixed reference axis of the radar system for the second direction angle β.

[0072] The azimuth angle Φ, elevation angle Θ, and elevation height h can be accurately determined for the object target 22 even if the object target 22 is above or below the elevation reference plane 31 from the first direction angle α and the second direction angle β.

[0073] The method for determining the elevation variables, i.e., elevation angle .THETA. and elevation height h, and the azimuth angle of the object target 22, is described below.

[0074] For this purpose, a radar signal 20 is emitted using a radiating antenna Tx of the radar system 14. An echo signal 24 reflected by an object target 22 can be received using a receiving antenna Rx and converted into an electrical signal.

[0075] The first direction angle α is determined from the phase difference between the echo signals 24 received using the individual receive antennas Rx. Furthermore, the radial velocity V R and the distance R are determined. Furthermore, the moving speed V of the vehicle 10 is determined. H is determined using the speed measurement system 34.

[0076] It is then checked whether the detected object target 22 is stationary or moving. For this purpose, the radial velocity V R and the movement speed V H A check term in the form of the difference between the product of and the cosine of the first direction angle α is compared with a first limit value TH1 and a second limit value TH2 as follows:

number

[0077] If the value of the check term lies between the two limit values ​​TH1 and TH2, the object target 22 is assumed to be stationary. In the case of a stationary object target 22, the following determination of the azimuth angle Φ and the elevation angle Θ can be performed more accurately than is possible with a moving object target 22. Therefore, in order to obtain more accurate results, the method is continued only using the object target 22 when it is stationary. If the check with the check term shows that the object target 22 is not stationary, the method of determining the azimuth angle Φ and the elevation angle variables, i.e. the elevation angle Θ and the elevation height h, is performed again using another object target 22.

[0078] Assuming that the check result indicates that the detected object target 22 is stationary, the first direction angle α, the range R, the radial velocity V R , and movement speed V H from which the second direction angle β is determined. This can be done by calculation or by using a conversion table 36.

[0079] The calculation is carried out, for example, with the help of the following trigonometric relations:

number

number

[0080] Alternatively or additionally, the second direction angle β can be determined by means of a conversion table 36. For this purpose, for example, a group of conversion tables 36 is stored in the control and evaluation device. A visualization of one of these conversion tables 36 is shown by way of example in FIG. 5. The conversion tables 36 can be determined in advance, for example in the course of a calibration of the radar system 14, for example at the end of a production line, and can be stored, for example, in a corresponding storage medium of the control and evaluation device 32.

[0081] Each conversion table 36 in the family corresponds to a particular travel speed V H This corresponds to the movement speed V H The first direction angle α, the second direction angle β, and the radial velocity V R The conversion table 36 includes, for example, a relationship between the first direction angle α, the radial velocity V R , and a corresponding second direction angle β.

[0082] In the conversion table 36 shown in FIG. 5, the first direction angle α is shown in the horizontal direction and the second direction angle β is shown in the vertical direction. R is shown in the corresponding field.

[0083] For the sake of clarity, and purely by way of example, values ​​from 10° to 70° are shown for the first direction angle α in increments of 10, and values ​​from 10° to 70° are shown for the second direction angle β in increments of 10. R is shown as an example with values ​​between 5 m / s and 20 m / s. In practice, the conversion table 36 may contain significantly more values ​​for the first direction angle α and the second direction angle β. R can also contain significantly more different negative and positive values.

[0084] Movement speed V H The matching conversion table 36 is used to determine the second direction angle β. H If there is no matching conversion table 36 for the current moving speed V H A conversion table 36 for the closest moving speed to the first direction angle α can now be used. The corresponding second direction angle β is calculated based on the already determined first direction angle α and the already determined radial speed V R , is obtained from the corresponding conversion table 36.

[0085] For example, the radial velocity V R For example, the first direction angle α and the radial velocity V R If multiple second direction angles β are available for x, then for example a validity check (not of further interest here) may be performed to check which of the two provided second direction angles β is valid.

[0086] The azimuth angle Φ and the elevation angle Θ are determined by trigonometry from the first direction angle α, the second direction angle β, and the distance R. Alternatively or additionally, the azimuth angle Φ and the elevation angle Θ can be determined, for example, with the aid of one or more suitable conversion tables from the first direction angle α, the second direction angle β, and the distance R.

[0087] The elevation height h of the object target 22 is calculated from the following mathematical relationship:

number

[0088] Alternatively or additionally, the elevation angle height h can be determined from the elevation angle Θ and the distance R instead of being determined from the first direction angle α, the second direction angle β, and the distance R.

[0089] For example, the following check, which can be performed using means of the driver assistance system 12, can be used to establish, using the elevation height h, whether the object target 22 is located low enough or high enough for the vehicle 10 to drive above or below it without colliding with it:

Claims

1. 1. A method for determining at least one elevation angle variable (Θ, h) of an object target (22) of an object (18), detected in particular by a radar system (14) of a vehicle (10) relative to an elevation angle reference plane (31), comprising: Using the radar system (14), a radar signal (20) is emitted and an echo signal (24) of the radar signal (20) reflected by the object target (22) is received; The moving speed (V Ｈ ) is determined, The radial velocity (V) of the at least one object target (22) relative to the radar system (14). Ｒ ) is determined using the radar system (14) from the received echo signals (24); a first directional variable (α) characterizing a direction of the object target (22) relative to a first reference region (y) fixed relative to the radar system (14) is determined using the radar system (14) from the received echo signals (24); A second directional variable (β) characterizing the direction of the object target (22) relative to a second reference area (x) fixed relative to the radar system (14) is calculated by multiplying the first directional variable (α), the radial velocity (V Ｒ ), and the moving speed (V Ｈ ) is determined by At least one elevation angle variable (Θ, a) ​​of the object target (22) is determined by at least one of the directional variables (α, β); A radar signal (20) is emitted using at least one antenna (Tx) of the radar system (14) and an echo signal (24) is received using at least two antennas (Rx) of the radar system (14), the respective phase centers (28) of the antennas (Tx, Rx) being arranged along a virtual antenna axis (30) extending parallel to the elevation reference plane (31); The method according to claim 1, characterized in that the first directional variable (α) is determined relative to a first reference axis (y) fixed relative to the radar system (14) as the reference region, and the second directional variable (β) is determined relative to a second reference axis (x) fixed relative to the radar system (14) as the reference region.

2. 2. The method of claim 1, characterized in that the first directional variable (α) is determined from the phase shift between echo signals (24) of the same radar signal (20) received using different antennas (Rx).

3. The second directional variable (β) is a function of the first directional variable (α), the radial velocity (V Ｒ ), and the moving speed (V Ｈ ) is calculated from a mathematical relationship, in particular a trigonometric relationship, using a second directional variable (β) in the form of a second directional angle, in particular the radial velocity (V Ｒ ) and the arcsine of the quotient of the moving speed (V Ｈ 3. The method according to claim 1, wherein the first directional variable (α) is calculated as the product of α and the cosine of a first directional variable (α) in the form of a first directional angle.

4. The second direction variable (β) is a function of the first direction variable (α), the second direction variable (β), and the radial velocity (V Ｒ ), and the moving speed (V Ｈ ), in particular the second directional variable (β) is obtained from a conversion table (36) that contains an association between the first directional variable (α) and the radial velocity (V Ｒ ) including a second directional variable (β) as a function of the respective movement speeds (V Ｈ 4. The method according to claim 1, wherein the first and second inputs are taken from a conversion table (36) corresponding to the first and second inputs.

5. 5. The method according to claim 1, wherein the first directional variable (α) and the second directional variable (β) are implemented in the form of angles.

6. 6. A method according to claim 1, characterized in that the two reference axes (x, y) are specified to span a plane extending parallel to or within the elevation reference plane (31).

7. 7. The method according to claim 1, characterized in that before the determination of the second directional variable (β), it is checked whether the detected object target (22) is stationary, and if the object target (22) is not stationary, the method for determining at least one elevation angle variable (Θ, h) is terminated for this object target (22), and if not, the method for determining at least one elevation angle variable (Θ, h) is continued.

8. To check whether the object target (22) is stationary, the radial velocity (V Ｒ ) and the moving speed (V Ｈ ) and the cosine of the first directional variable (α), The difference is equal to at least one limit value (TH １ , T.H. ２ ) and depending on the result of the comparison, the object target (22) is assumed to be stationary and the method for determining the at least one elevation angle variable (Θ, h) is continued, otherwise the method for this object target (22) is terminated; and / or The difference is two specified limits (TH １ , T.H. ２ ), and the difference is compared to the two limit values ​​(TH １ , T.H. ２ 8. The method of claim 7, wherein if the elevation angle θ,h is between θ,h, the object target (22) is assumed to be stationary and the method for determining the at least one elevation angle variable (θ,h) continues, and if not, the method ends for this object target (22).

9. 9. The method according to claim 1, characterized in that the at least one elevation angle variable (Θ, a) ​​and / or the azimuth angle (Φ) of the object target (22) is calculated by the first direction variable (α) and the second direction variable (β) and / or is obtained from at least one conversion table.

10. A radar system (14) for a vehicle (10), comprising: at least one antenna (Tx) for radiating a radar signal (20); at least one antenna (Rx) for receiving an echo signal (24) from a radar signal (20) reflected by an object target (22); A means for determining at least one elevation angle variable (Θ, h) of an object target (22) of an object (18) detected using said radar system (14) relative to an elevation angle reference plane (31), said means comprising: The received echo signals (24) provide a radial velocity (V Ｒ ) determining the means for determining, from the received echo signals (24), a first directional variable (α) characterizing the direction of the object target (22) relative to a first reference region (y) fixed relative to said radar system (14); A second directional variable (β) characterizing the direction of the object target (22) relative to a second reference area (x) fixed relative to the radar system (14) is calculated by multiplying the first directional variable (α) of the radar system (14), the radial velocity (V Ｒ ), and the moving speed (V Ｈ ) determining whether and means for determining at least one elevation angle variable (Θ, h) of an object target (22) according to at least one of said directional variables (α, β), The radar system (14), at least one antenna (Tx) that can be used to radiate a radar signal (20) and at least two antennas (Rx) that can be used to receive an echo signal (24) from the radar signal (20) reflected by an object target (22), the respective phase centers (28) of the antennas (Tx, Rx) being disposed along a virtual antenna axis (30) that extends parallel to the elevation reference plane (31); A radar system (14), characterized in that it has a first reference axis (y) fixed relative to the radar system (14) as the reference region of the first directional variable (α) and a second reference axis (x) fixed as the reference region of the second directional variable (β).

11. A vehicle (10) having at least one radar system (14), the at least one radar system (14) comprising: at least one antenna (Tx) for radiating a radar signal (20); at least one antenna (Rx) for receiving an echo signal (24) from a radar signal (20) reflected by an object target (22); A means for determining at least one elevation angle variable (Θ, h) of an object target (22) of an object (18) detected using said radar system (14) relative to an elevation angle reference plane (31), said means comprising: The received echo signals (24) provide a radial velocity (V Ｒ ) determining the means for determining, from the received echo signals (24), a first directional variable (α) characterizing the direction of the object target (22) relative to a first reference region (y) fixed relative to said radar system (14); A second directional variable (β) characterizing the direction of the object target (22) relative to a second reference area (x) fixed relative to the radar system (14) is calculated by multiplying the first directional variable (α) of the radar system (14), the radial velocity (V Ｒ ), and the moving speed (V Ｈ) determining whether and means for determining at least one elevation angle variable (Θ, h) of an object target (22) according to at least one of said directional variables (α, β), The at least one radar system (14) at least one antenna (Tx) that can be used to radiate a radar signal (20) and at least two antennas (Rx) that can be used to receive an echo signal (24) from the radar signal (20) reflected by an object target (22), the respective phase centers (28) of the antennas (Tx, Rx) being disposed along a virtual antenna axis (30) that extends parallel to the elevation reference plane (31); A vehicle (10), characterized in that it has a first reference axis (y) fixed relative to the at least one radar system (14) as the reference region of the first directional variable (α) and a second reference axis (x) fixed as the reference region of the second directional variable (β).

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