Method and device for computer-aided verification of the installation position of at least one UWB sensor

Abstract

A method for computer-aided verification of the installation position of at least one UWB sensor (10; 210, 220) is described. The sensor comprises two antennas (11, 12; 211, 212, 221, 222) and is located in a vehicle interior (5) under the headliner (2) of a motor vehicle. A correct installation position exists when the at least one UWB sensor (10; 210, 220) is arranged in space at a predefined position with respect to a vehicle coordinate system of the motor vehicle at a predefined angular relationship. In the method, the at least one UWB sensor (10; 210, 220) emits at least one radar pulse (RI) with a known transmission power, wherein the at least one radar pulse (RI) is reflected as a corresponding radar echo (RE) by a reference object (30) which is located in the vehicle interior (5) at and in a defined position with respect to the vehicle coordinate system.The radar echo (RE) is received by the at least one UWB sensor (10; 210, 220) and evaluated for the correctness of the installation position of the at least one UWB sensor (10; 210, 220), whereby a faulty installation position is concluded if at least one of the following diagnostic criteria is met: the signal difference between the transmit power of the at least one radar pulse (RI) and the receive power of the corresponding radar echo (RE) exceeds a predefined threshold; the time of flight that a respective radar pulse (RI) requires from the at least one UWB sensor (10; 210, 220) to the reference object (30) and back to the at least one UWB sensor (10; 210, 220) does not correspond to a predefined time of flight value or does not fall within a predefined time of flight range.

Description

[0001] The invention relates to a method and a device for computer-assisted checking of the installation position of at least one UWB sensor (UWB = ultra-wideband), which comprises two antennas and is arranged in a vehicle interior under the roof lining of a motor vehicle.

[0002] The principle of a UWB sensor, which is a radar sensor, is to emit radar pulses and then receive radar echoes reflected from objects. Typically, a large number of radar pulses are emitted within a specified period of time, which are then received as radar echoes. The duration of a single radar pulse is usually in the range of a few nanoseconds to several hundred picoseconds. By appropriately evaluating the radar echoes, signs of life from vehicle occupants and thus their presence can be detected. Detection can be determined, for example, by the rise and fall of the vehicle occupant's chest as a result of breathing. Depending on the vehicle, one or more UWB sensors can be provided for complete monitoring of the vehicle interior.

[0003] By design, the UWB sensor has a specific viewing area or field of view. Starting from a transmitting antenna, the radar pulses propagate in a funnel-shaped field of view. In order to detect all intended volume areas in the vehicle interior, the UWB sensor must be correctly installed. A correct installation position is achieved when the UWB sensor is arranged at a predefined position in space with a predefined angular relationship relative to the vehicle's coordinate system. In principle, any coordinate system can be used as the vehicle coordinate system, although a Cartesian coordinate system oriented along a vehicle's longitudinal axis, a vehicle's transverse axis, and a vehicle's vertical axis is typically used.

[0004] The installation position of the UWB sensor must be verified not only after initial installation under the headliner, but also after a replacement, for example. Since the installation position under the headliner is not visible, additional tools are required to verify the correct installation position.

[0005] It is an object of the present invention to provide a method and a device which enable a simple checking of the installation position of the UWB sensor.

[0006] These objects are achieved by a method according to the features of claim 1, a computer program product according to the features of claim 9 and a device according to the features of claim 10. Advantageous embodiments emerge from the dependent claims.

[0007] According to a first aspect of the present invention, a method for computer-assisted verification of the installation position of at least one UWB sensor is proposed. The UWB sensor is an ultra-wideband radar sensor. Each UWB sensor comprises two antennas and is arranged in a vehicle interior under the roof of a motor vehicle. A correct installation position of each UWB sensor exists when the at least one UWB sensor is arranged at a predefined position in a predefined angular relationship in space with respect to a vehicle coordinate system of the motor vehicle.

[0008] The preferred vehicle coordinate system is a Cartesian coordinate system, which has a longitudinal axis, a transverse axis, and a vertical axis, each aligned at right angles to each other. Other coordinate systems related to the vehicle could also be used.

[0009] A predefined position of a respective UWB sensor with respect to the vehicle coordinate system is understood to be an arrangement of predefined coordinates relative to the axes of the vehicle coordinate system. A predefined angular relationship in space means that a respective sensor axis has a predefined angular relationship to the axes of the vehicle coordinate system. Any other coordinate system could be used instead of a Cartesian vehicle coordinate system.

[0010] According to the method according to the invention, the at least one UWB sensor emits at least one radar pulse with a known transmission power. The at least one radar pulse is reflected as a corresponding radar echo by a reference object arranged in the vehicle interior at or in a defined position relative to the vehicle coordinate system. The radar echo is received by the at least one UWB sensor. The radar echo is evaluated for the correctness of the installation position of the at least one UWB sensor.

[0011] An incorrect installation position is determined if at least one of the following diagnostic criteria is met: (1) The signal difference between the transmitted power of the at least one radar pulse and the received power of the corresponding radar echo exceeds a predetermined threshold. (2) The transit time required by a respective radar pulse from the at least one UWB sensor to the reference object and back to the at least one UWB sensor does not correspond to a predetermined transit time value or does not fall within a predetermined transit time range.

[0012] UWB sensors have a specific field of view, depending on the antenna design. This field of view must ensure optimal coverage of the vehicle interior, for example, to detect the presence of passengers inside. For design reasons, the UWB sensors are installed under or behind the roof lining. This process not only allows for the determination of correct installation but also ensures the performance of the vehicle occupant detection system, since the correct orientation of the UWB sensor and its field of view have a significant impact on the system's performance.

[0013] The method according to the invention enables self-diagnosis by evaluating the radar pulses emitted by the at least one UWB sensor, which are reflected by a reference object arranged at a known position relative to the at least one UWB sensor in the vehicle interior. The evaluation is carried out based on the received radar echo in relation to a signal separation, which must have a specific value or lie within a specific power range when the UWB sensor is installed as intended, and / or in relation to the time of flight of the emitted radar pulse reflected by the reference object. In this way, the correct installation position of the at least one UWB sensor can be checked without the at least one UWB sensor having to be visible from the outside.

[0014] Verification of the correct installation position can be performed not only once, e.g., after initial installation or replacement following a defect, but also, for example, every time the vehicle is restarted. This ensures that the position-dependent functionality of the UWB sensor is not adversely affected throughout the vehicle's lifetime.

[0015] In a practical embodiment, two UWB sensors are installed in the motor vehicle. Both sensors are arranged under the roof lining of the motor vehicle. It is expedient for a first, receiving UWB sensor to receive at least one radar pulse from a second, transmitting UWB sensor directly, and for the radar echo to be evaluated. The term "directly" refers to a direct connection (line of sight) without radar-opaque materials in the signal propagation path between the first and second UWB sensors. The direct connection thus runs under the roof lining, approximately parallel to it.

[0016] To determine whether a correct installation position is present, it is expedient for the first UWB sensor to receive the at least one radar pulse at its two antennas, wherein the signals received at the two antennas are processed to check the installation position of the first and / or second UWB sensor.

[0017] The radar echo can be processed by a processing unit of the at least one UWB sensor. The processing can also be performed by a higher-level processing unit connected to the at least one UWB sensor. To carry out the diagnostic method, a higher-level processing unit can, for example, trigger the transmission of the at least one radar pulse and appropriately process the resulting radar echo received by the at least one UWB sensor.

[0018] By receiving at least one radar pulse at both antennas by the first, receiving UWB sensor, it is possible to determine a phase difference between the two propagation paths between the transmitting antenna of the second UWB sensor and the two receiving antennas of the first UWB sensor. A propagation time difference between the two signals can then be determined from the phase difference. In particular, an angular relationship between the respective sensor axes of the first and second UWB sensors is determined from the propagation time difference of the two signals. The determined angular relationship is compared with a predetermined angular relationship in order to determine the correctness of the installation position. The predetermined angular relationship can be determined during the design of the sensor system with regard to the correct installation position and the vehicle coordinate system through tests and / or simulations and / or calculations.

[0019] According to a further advantageous embodiment, the distance between respective sensor reference points of the first and second UWB sensors is determined from the travel times required by a respective radar pulse from the first UWB sensor and the second UWB sensor to the reference object and back to the respective UWB sensor, and from a trigonometric calculation. According to this advantageous embodiment, a time-of-flight calculation of the travel time of the radar pulse from the first and second UWB sensors to the reference object and its reflection is determined, wherein the trigonometric calculation of the distance between respective sensor reference points enables an additional determination of the installation position of the sensors.

[0020] According to a further expedient embodiment, a component in the vehicle interior of the motor vehicle is used as the reference object. This can be, for example, a characteristic surface, such as the surface of a rotary push-button switch arranged on the center tunnel or a gear selector lever, whose geometric properties are known and which exhibits good reflectivity. Alternatively or additionally, a component incorporated into the vehicle interior of the motor vehicle, in particular a reflector, can be used as the reference object. A mirror, for example, can be used as a reflector.

[0021] According to a second aspect, a computer program product is proposed which comprises instructions which, when the program is executed by a computing unit, cause the computing unit to carry out the method according to one or more embodiment variants.

[0022] According to a third aspect, a device is proposed for computer-assisted checking of the installation position of at least one UWB sensor, which comprises two antennas and is arranged in a vehicle interior under the roof of a motor vehicle. A correct installation position exists when the at least one UWB sensor is arranged at a predefined position in space with respect to a vehicle coordinate system of the motor vehicle, in a predefined angular relationship. The at least one UWB sensor is designed to emit at least one radar pulse with a known transmission power, wherein the at least one radar pulse is reflected as a corresponding radar echo by a reference object arranged in the vehicle interior at or in a defined position with respect to the vehicle coordinate system. The at least one radar sensor is further designed to receive the radar echo.A computing unit is designed to evaluate the radar echo for the correctness of the installation position of the at least one UWB sensor, wherein an incorrect installation position is concluded if at least one of the following diagnostic criteria is met: (1) The distance between the transmission power of the at least one radar pulse and the reception power of the corresponding radar echo exceeds a predetermined threshold value; (2) The travel time required by a respective radar pulse from the at least one UWB sensor to the reference object and back again to the at least one UWB sensor does not correspond to a predetermined travel time value or does not fall within a predetermined travel time range.

[0023] In further embodiments, the device is configured to carry out one or more further embodiments of the method according to the invention.

[0024] The invention is explained in more detail below using an exemplary embodiment in the drawing. They show: Fig. 1 shows a schematic representation of an apparatus according to the invention for computer-assisted checking of the installation position of a UWB sensor; Fig. 2 shows a schematic representation of another embodiment of a device for computer-assisted checking of the installation position of two UWB sensors; and Fig. 3 a schematic representation of two UWB sensors and a reference object as well as the resulting distances for a trigonometric calculation of the distance between the two UWB sensors.

[0025] Fig. Figure 1 shows a schematic representation of an inventive device for computer-assisted checking of the installation position of a UWB sensor 10. The UWB sensor 10 comprises, in a known manner, two antennas 11, 12 coupled to a transmitting / receiving unit 13. For example, the antenna 11 serves as a transmitting antenna (Tx) and the antenna 12 serves as a receiving antenna (Rx). The transmitting / receiving unit 13 is configured, in a known manner, to transmit radar pulses RI via the antenna 11 and to process the radar echoes RE received by the antenna 12.

[0026] The UWB sensor 10 is arranged under a roof lining 2 of a motor vehicle (not shown in detail) in order to monitor its interior 5. For example, the UWB sensor 10 is arranged near the interior mirror under the roof lining 2 and oriented such that the radar pulses RI it emits are directed toward the front and rear seats in order to detect the presence of occupants. The presence of occupants can then be determined from the radar echoes RE reflected by the objects (both static objects of the motor vehicle and / or vehicle occupants). For this purpose, the radar echoes RE are evaluated in a known manner by a computing unit 3, which is connected to the transmitting / receiving unit 13.

[0027] The UWB sensor 10 has a sensor axis 14 that characterizes it or is assigned to it, as well as a sensor reference point 15, e.g., the center of a housing of the UWB sensor 10. Based on the sensor axis 14 and the sensor reference point 15, its position in space can be characterized with respect to a vehicle coordinate system FK of the motor vehicle.

[0028] For example, a Cartesian coordinate system can be used, in which the x-axis represents the vehicle's longitudinal direction, the y-axis the vehicle's transverse direction, and the z-axis the vehicle's vertical direction. The position of the UWB sensor 10 can be defined for its sensor reference point 14 by coordinates x, y, and z in the vehicle coordinate system FK. The installation position of the UWB sensor is further defined by a predefined angular relationship in space, e.g., by the respective angles of the axes of the vehicle coordinate system FK with respect to the direction of extension of the sensor axis 14.

[0029] Depending on the antennas 11, 12 used, the UWB sensor 10 has a predetermined field of view 16, which generally extends in a funnel shape from the antennas 11, 12 towards the spatial volume to be monitored. In order to ensure optimal coverage of the vehicle interior 5, e.g., to detect the presence of passengers in the vehicle interior 5, the correct installation position of the UWB sensor 10 is required. A correct installation position exists when the UWB sensor 10 has the above-mentioned predefined angular relationship in space with respect to the vehicle coordinate system FK of the motor vehicle at the likewise predefined position (x, y, z). However, since the UWB sensor 10 is installed behind the roof liner 2, correct installation cannot be ensured by visual inspection.

[0030] For this purpose, a reference object 30 is arranged in the vehicle interior 5, wherein the position of the reference object 30 is defined with respect to the vehicle coordinate system FK 30. The position can be defined by one or more object axes and an object reference point. The reference object 30 can, for example, be a component in the vehicle interior 5 of the motor vehicle. This could, for example, be a highly reflective surface, e.g., a gear selector lever, a rotary push-button, and the like. Likewise, a component, in particular a reflector, introduced into the vehicle interior 5 of the motor vehicle 1 can be used as the reference object 30.

[0031] If the UWB sensor 10 transmits a radar pulse RI with a known transmission power, the radar pulse RI is reflected by the reference object 30 as a radar echo.

[0032] The radar echo RE is received by the UWB sensor 10. By evaluating the radar echo RE, the correct installation position of the UWB sensor 10 can be determined.

[0033] An incorrect installation position is concluded if at least one of the following two diagnostic criteria is met: (1) The signal difference between the transmitted power of the radar pulse RI and the received power of the radar echo RE exceeds a specified threshold. The specified threshold was previously determined during system design. The threshold can be determined through experiments, simulations, or tests. (2) The travel time required by a radar pulse RI from the UWB sensor 10 to the reference object 30 and back to the UWB sensor 10 does not correspond to a specified travel time value or does not fall within a specified travel time range. The travel time or the specified travel time range can be determined during the system design through experiments, simulations, or tests.

[0034] The time from the transmission of the radar pulse to the reception of the radar echo at the UWB sensor 10 is also referred to as the time of flight. If there is a deviation in the signal separation and / or the time of flight from the specified reference values ​​or ranges, this may indicate an incorrect installation position. In this case, the installation position of the UWB sensor 10 must be checked again.

[0035] Fig. Figure 2 shows a second embodiment of a device according to the invention for computer-assisted checking of the installation position of two UWB sensors. Shown are a first, receiving UWB sensor 210 and a second UWB sensor 220 emitting a radar pulse RI. The first and second UWB sensors 210, 220 are each arranged under the roof liner 2 of the motor vehicle (not shown in detail). Using the proposed method, a computer-assisted check of the installation position of the first and second UWB sensors 210, 220 is to be carried out.

[0036] The first and second UWB sensors 210, 220 are constructed identically to the previously described UWB sensor 10. The antennas of the first UWB sensor 210 are designated 211, 212, a transmitting / receiving unit 213, the sensor axis 214, and the sensor reference point 215. The second UWB sensor 220 comprises antennas 221, 222, a transmitting / receiving unit 223, a sensor axis 224, and a sensor reference point 225. The orientation of the sensor axes 214, 224 is rotated by 90° with respect to the vehicle coordinate system FK, which is also shown, merely for illustrative purposes. The illustrated orientation does not necessarily correspond to the actual orientation used during implementation in the motor vehicle.

[0037] The transmit / receive units 213, 223 are connected to a processing unit 3, which executes and controls the proposed method. As shown in the drawing, the processing unit 3 can represent a higher-level processing unit that is a separate component from the UWB sensors 210, 220. Alternatively, the processing unit 3 could be the processing unit of the first or second UWB sensor 210, 220.

[0038] In the Fig. In the embodiment shown in Figure 2, alternatively or in addition to the use of the radar echo RE reflected by the reference object 30, a radar pulse RI is evaluated, which the first, receiving UWB sensor 210 receives directly from the second, transmitting UWB sensor 220. The "direct path" is understood to mean a direct connection 31, 31' (line of sight) without radar-opaque materials. The direct connection 31, 31' thus runs, as shown Fig. 2 schematically shows, under the headliner 2.

[0039] The first UWB sensor 210 receives the radar pulse RI at its two antennas 211, 212, and the signals received at the two antennas 211, 212 (with the different propagation paths 31, 31') are processed to verify the installation position of the first and / or second UWB sensor. An angular relationship between the respective sensor axes 214, 224 of the first and second UWB sensors 210, 220 is determined from a propagation time difference between the two signals. The determined angular relationship is compared with the specified angular relationship to determine the correctness of the installation position of the first and / or second UWB sensor. By calculating the time difference between signals 31 and 31' and the absolute time of light, it can then be determined whether the installation of the UWB sensors 210, 220 corresponds to the specification or whether a change has occurred compared to the original state or the specification.

[0040] This eliminates the need for laborious disassembly of the headliner for diagnostics. Another advantage is that expensive and complex testing equipment is not required, and self-diagnosis of the correct position and orientation of the fields of view of the UWB sensors 210 and 220 in the interior is possible.

[0041] From a propagation time of at least one radar pulse RI, a distance between respective sensor reference points 215, 225 of the two UWB sensors 210, 220 can be determined. The determined distance A ( Fig. 3) can then be compared with a given distance from the specification to determine the correctness of the installation position.

[0042] In addition, the distances B and C can be calculated from the travel times required by a respective radar pulse RI from the first UWB sensor 210 and the second UWB sensor 220 to the reference object 30 and back to the respective UWB sensor. Fig. 3. From a trigonometric calculation, the distance A between the respective sensor reference points 215, 225 of the two UWB sensors 210, 220 can then be calculated. This calculation can be carried out using the Fig. 3 shown geometric situation.

[0043] Shown in Fig. 3 shows a top view of the first and second UWB sensors 210, 220 and the reference object 30. A denotes the distance between the sensor reference points 215, 225 (not shown) of the UWB sensors 210, 220. B denotes the distance between the sensor reference point 215 of the UWB sensor 210 and the reference object 30. C denotes the distance between the sensor reference point 225 of the UWB sensor 220 and the reference object 30. d, e, and f represent further lengths known from the system design, from which the distance A can be indirectly determined. Here, the following applies: The calculation is based on the following geometric conditions and reformulations. The following applies: A=e+e and B2=d2+f2 and C2=e2+f2

[0044] This means: C2=e2+B2−d2 C2=B2+(e+d)(e−d) C2=B2+A(e−d) A=(C2−B2) / (e−d).

[0045] After the distance A has been determined by this trigonometric calculation, a comparison can be made with the length determined by the transit time measurement. The trigonometric calculation allows a plausibility check of the Fig. 2 described self-diagnosis procedure. List of reference symbols 2 headliner 3 Computing unit 5 Vehicle interior 10 UWB sensors 11 first antenna (Tx) 12 second antenna (Rx) 13 Transmitting / receiving unit 14 Sensor axis 15 Sensor reference point 16 Field of View 210 first UWB sensor 211 first antenna (Rx) 212 second antenna (Rx) 213 Transceiver unit 214 Sensor axis 215 Sensor reference point 220 second UWB sensor 221 first antenna (Tx) 222 second antenna (Rx) 223 Transceiver unit 224 Sensor axis 225 Sensor reference point 226 Field of View 30 reference objects 31, 31' direct connection (line of sight) A Distance between the sensor reference points of the UWB sensors 210, 220 B Distance between sensor reference point of the UWB sensor 210 and reference object C Distance between sensor reference point of the UWB sensor 220 and reference object d, e, f lengths

Claims

[1] Method for computer-assisted checking of the installation position of at least one UWB sensor (10; 210, 220) which comprises two antennas (11, 12; 211, 212, 221, 222) and which is arranged in a vehicle interior (5) under the roof lining (2) of a motor vehicle, wherein a correct installation position exists when the at least one UWB sensor (10; 210, 220) is arranged in a predefined angular relationship in space at a predefined position with respect to a vehicle coordinate system of the motor vehicle, in which - the at least one UWB sensor (10; 210, 220) emits at least one radar pulse (RI) with a known transmission power, wherein the at least one radar pulse (RI) is reflected as a corresponding radar echo (RE) by a reference object (30) arranged in the vehicle interior (5) at and in a defined position with respect to the vehicle coordinate system; - the radar echo (RE) is received by the at least one UWB sensor (10; 210, 220) and evaluated for the correctness of the installation position of the at least one UWB sensor (10; 210, 220), wherein an incorrect installation position is concluded if at least one of the following diagnostic criteria is met: - the signal difference between the transmitted power of at least one radar pulse (RI) and the received power of the corresponding radar echo (RE) exceeds a predetermined threshold value; - the propagation time required by a respective radar pulse (RI) from the at least one UWB sensor (10; 210, 220) to the reference object (30) and back again to the at least one UWB sensor (10; 210, 220) does not correspond to a predetermined propagation time value or does not fall within a predetermined propagation time range. [2] Method according to claim 1, characterized bythat a first, receiving UWB sensor (210) receives at least one radar pulse from a second, transmitting UWB sensor (220) directly and the radar echo is evaluated. [3] Method according to claim 2, characterized by that the first UWB sensor (210) receives the at least one radar pulse at its two antennas (211, 212), wherein the signals received at the two antennas (211, 212) are processed to check the installation position of the first and / or second UWB sensor (210, 220). [4] Method according to claim 3, characterized by that an angular relationship between respective sensor axes (213, 223) of the first and second UWB sensors (210, 220) is determined from a propagation time difference of the two signals, wherein the determined angular relationship is compared with a predetermined angular relationship in order to conclude the correctness of the installation position. [5] Method according to claim 3 or 4, characterized byin that a distance between respective sensor reference points (215, 225) of the first and second UWB sensors (210, 220) is determined from a propagation time of the at least one radar pulse, wherein the determined distance (A) is compared with a predetermined distance in order to conclude the correctness of the installation position. [6] Method according to one of claims 2 to 5, characterized by that the distance between respective sensor reference points (215, 225) of the first and second UWB sensors (210, 220) is determined from the travel times required by a respective radar pulse from the first UWB sensor (210) and the second UWB sensor (220) to the reference object (30) and back again to the respective UWB sensor (210, 220), and from a trigonometric calculation. [7] Method according to one of the preceding claims, characterized by that a component in the vehicle interior (5) of the motor vehicle is used as the reference object (30). [8] Method according to one of the preceding claims, characterized by that a component, in particular a reflector, introduced into the vehicle interior (5) of the motor vehicle is used as the reference object (30). [9] A computer program product comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method according to any one of claims 1 to 8. [10] Device for computer-assisted checking of the installation position of at least one UWB sensor (10; 210, 220) which comprises two antennas (11, 12; 211, 212, 221, 222) and which is arranged in a vehicle interior (5) under the roof lining (2) of a motor vehicle, wherein a correct installation position exists when the at least one UWB sensor (10; 210, 220) is arranged in a predefined angular relationship in space at a predefined position with respect to a vehicle coordinate system of the motor vehicle, in which - the at least one UWB sensor (10; 210, 220) is designed to - to transmit at least one radar pulse (RI) with a known transmission power, wherein the at least one radar pulse (RI) is reflected as a corresponding radar echo (RE) by a reference object (30) which is arranged in the vehicle interior (5) at and in a defined position with respect to the vehicle coordinate system; - to receive the radar echo (RE); and - a computing unit (3) which is designed to evaluate the radar echo (RE) for the correctness of the installation position of the at least one UWB sensor (10; 210, 220), wherein an incorrect installation position is concluded if at least one of the following diagnostic criteria is met: - the signal difference between the transmitted power of at least one radar pulse (RI) and the received power of the corresponding radar echo (RE) exceeds a predetermined threshold value; - the propagation time required by a respective radar pulse (RI) from the at least one UWB sensor (10; 210, 220) to the reference object (30) and back again to the at least one UWB sensor (10; 210, 220) does not correspond to a predetermined propagation time value or does not fall within a predetermined propagation time range. [11] Device according to claim 10, characterized by that it is adapted to carry out the method according to one of claims 2 to 8.

Images