Method for determining the relative position of sensors of a motor vehicle

Abstract

The invention relates to a method for determining the relative position of sensors (18) of a motor vehicle (10) to a reference point (R P ). The method comprises the steps of determining (A) a relative distance between sensors (18) of the motor vehicle (10) among each other and / or to the reference point (R P ) by means of a wireless connection, measuring (B) dynamic values ​​of the motor vehicle (10) for each sensor (18), by means of a dynamic measuring unit (26) assigned to each sensor (18), transmitting (C) the relative distance and the dynamic values ​​for each sensor (18) to at least one computing unit (38), and determining (E) a relative orientation of the sensors (18) to one another and / or to the reference point (R P), by comparing the dynamic values ​​determined for each sensor (18). Furthermore, the method comprises the steps of determining (F) calibration parameters by transforming the relative distances and orientations of the sensors (18) into a common coordinate system to the reference point (R P ), comparing (H) the determined calibration parameters of the sensors (18) with stored calibration parameters, determining (I) a deviation (ΔP K ) between the determined calibration parameters and the stored calibration parameters, and performing (J) a predefined action if a deviation (ΔP K ) of at least one sensor (18) above a defined limit value (G W ) lies.

Description

[0001] The present invention relates to a method for determining the relative position of sensors of a motor vehicle and a device for automatic calibration with which such a method can be carried out. State of the art

[0002] For partially and especially highly automated or autonomous driving systems, highly reliable detection of the surroundings is required as a basis for decision-making. For this purpose, multiple sensors and / or sensor technologies (radar, lidar, video, etc.) are installed on the vehicle in such a way that all-round visibility is achieved.

[0003] Modern vehicles have complex architectures and functions. To ensure the safety and functionality of the vehicle, a combination of multiple sensors is necessary. It is crucial that the sensors are precisely aligned (adjusted) and calibrated. Even slight inaccuracies in calibration or adjustment can result in significant systematic errors in environment detection. The calibration methods currently used require a special test setup, such as a calibration room.

[0004] DE 102 29 334 B4 describes a device and a method for calibrating sensors in a motor vehicle. The sensors can be radar sensors, image sensors, lidar sensors, or ultrasonic sensors. The motor vehicle with the sensors is aligned in front of a calibration object so that the sensors detect reference features on the calibration object. The sensors are calibrated with respect to these reference features. For this purpose, calibration data is generated, which is stored and used to correct the sensor data.

[0005] DE 10 2018 208 846 B4 describes a method for calibrating a sensor assembly. The sensor assembly comprises at least one camera and one radar sensor. The calibration process takes place after installation in the vehicle in order to detect deviations caused by the actual installation position. The calibration data for the optical sensor are determined using a visual pattern positioned in front of the optical sensor. A correction value for the sensor is calculated based on the determined calibration data.

[0006] The object underlying the invention is to provide a method and a device for calibrating sensors, with which a calibration of the sensors is possible in a simple and economical manner.

[0007] The object is achieved by a method having the subject matter of patent claim 1. Furthermore, the invention is achieved by a device for automatic calibration having the subject matter of patent claim 10. Preferred embodiments can be found in the dependent claims. Disclosure of the invention

[0008] The invention provides a method for determining the relative position of sensors of a motor vehicle to a reference point. The method comprises the steps of determining a relative distance between sensors of the motor vehicle and / or to the reference point using a wireless connection, measuring dynamic values ​​of the motor vehicle for each sensor using a dynamic measurement unit assigned to each sensor, and transmitting the relative distance and the dynamic values ​​for each sensor to at least one computing unit.In addition, the method comprises the steps of determining a relative orientation of the sensors to each other and / or to the reference point by comparing the dynamic values ​​determined for each sensor, determining calibration parameters by transforming the relative distances and orientations of the sensors into a common coordinate system to the reference point, comparing the determined calibration parameters of the sensors with stored calibration parameters, determining a deviation between the determined calibration parameters and the stored calibration parameters, and performing a predefined action if a deviation of at least one sensor is above a defined limit value.

[0009] A relative position is understood as a spatial position and orientation relative to a coordinate system defined at a reference point. The orientation indicates the alignment of the sensor within this coordinate system. A radio connection is advantageously used as a wireless connection. The dynamic values ​​include values ​​for accelerations and rotation rates experienced by such an acceleration measuring unit, and thus also the corresponding sensor. According to the invention, the relative distance and acceleration values ​​can be transmitted to the computing unit both wirelessly and wired.

[0010] This method enables simple and cost-effective calibration of sensors on a motor vehicle. In particular, a dedicated calibration room is no longer required. This method also eliminates the labor required for calibration. With this method, workshop personnel do not need to be trained in a specific calibration procedure. Furthermore, the method can also be performed while the vehicle is in operation. Accordingly, a misalignment or a loose sensor can be detected during operation. This can increase the safety of the vehicle.

[0011] In a preferred embodiment of the invention, the comparison of the calibration parameters and the determination of the deviation are performed on a common processing unit for all sensors. By using a common processing unit, a separate processing unit in each sensor is eliminated. A corresponding device can thus be provided more economically. Furthermore, processing on the common processing unit allows for better alignment of the calibration parameters of the various sensors.

[0012] In a further preferred embodiment of the invention, the comparison of the calibration parameters and the determination of the deviation are carried out on an external computing unit located outside the vehicle. Advantageously, such an external computing unit is provided in a cloud. In such an external computing unit, a computing unit can be provided which has greater computing power. Accordingly, a computing unit does not have to be provided for each motor vehicle. Such a device can therefore be provided more economically. Calculations on an external computing unit have the additional advantage that values ​​from other vehicles of the same type can be compared with these, so that deviations resulting from design-related changes can be identified and remedied in subsequent vehicle versions or during a vehicle workshop appointment.

[0013] Preferably, the comparison of the calibration parameters and the determination of the deviation are performed in a computing unit of the respective sensor. Such determination in a computing unit of the respective sensor provides a high level of redundancy, so that if a common computing unit fails, the calibration parameters can still be calculated. The multiple computing units also make it possible to detect a malfunction in a computing unit, causing it to be deactivated. This increases the safety of the motor vehicle.

[0014] In an advantageous development, the relative distances are determined by measuring the signal strength of a radio signal. The radio signal is advantageously a Bluetooth signal. By measuring the signal strength, the relative distance to another sensor or to the control unit can be precisely determined. By determining the signal strength of at least three other sensors or the control unit, a position in space can be determined. This makes it possible to precisely determine the position of a sensor.

[0015] Advantageously, the calibration parameters, the determined dynamic values, and the relative distances are stored. By storing these values, it is possible to monitor a deviation below the limit over time and predict when a workshop appointment is due to correct a deviation that exceeds the limit. This allows the deviation to be corrected before a sensor fails. The recorded values ​​can also be read out during such a workshop appointment, so that sensors whose deviation exceeds the limit in the near future can be corrected. This can thus increase the safety of the vehicle.

[0016] In another advantageous embodiment, deviations in the calibration parameters below the limit value are compensated for using software-based correction. This software-based correction of the deviation takes this deviation into account when outputting the sensor signals, so that the sensor signals are corrected accordingly. This makes it possible to ensure high accuracy for the sensor signals despite a deviation.

[0017] According to a practical implementation, if a deviation of at least one sensor exceeds a defined limit, the driver is informed. The driver can then receive a notification to visit a workshop so that this sensor can be realigned. The driver can also deactivate the measured values ​​of this sensor. This information allows the driver to decide early on what to do about the deviation.

[0018] According to a further advantageous embodiment, if a deviation of at least one sensor exceeds a defined limit, the driving function dependent on this sensor is downgraded. The downgrading of the driving functions is carried out automatically. This is particularly useful if such a deviation occurs during autonomous driving. Early detection of this deviation and the resulting downgrading can increase the safety of the motor vehicle.

[0019] The problem underlying the invention is additionally solved by a device for automatic calibration, with which the above-described inventive method can be carried out. The device comprises sensors with a dynamic measurement unit for measuring dynamic values, means for determining a relative distance, a communication unit for transmitting the measured values, and a computing unit for processing the measured values ​​of the sensors. With such a device for automatic calibration, the properties and advantages described above can be achieved. In particular, such a device can reduce the costs of calibrating the sensors.

[0020] In a preferred embodiment of the invention, the computing unit is provided in one of the sensors. By arranging the computing unit in one of the sensors, a computing unit for calculating the calibration parameters in the control unit can be omitted. This computing unit can also be provided as a redundant unit to check the computing unit in the control unit or to take over the calculation in the event of a failure of the computing unit in the control unit. The reliability of the device is thereby increased.

[0021] In a further preferred embodiment of the invention, the means for determining the relative distance comprise a GNSS receiver and / or a radio unit. The radio unit is both a transmitter and a receiver for a radio signal. The radio unit makes it possible to determine the position of other sensors based on their signal strength and to emit a radio signal so that one's own position can be determined via other sensors. Via triangulation, it is possible to determine the spatial position of the sensor. The spatial position can also be determined via the GNSS receiver, via which signals from a satellite positioning service can be received. The advantage of such a GNSS receiver is that no other sensors are necessary to determine the spatial position.However, it is advantageous to combine the spatial position via the radio unit and the GNSS receiver to achieve greater accuracy.

[0022] The method described above can, in particular, be computer-implemented, for example, and thus embodied in software. The invention therefore also relates to a computer program with machine-readable instructions that, when executed on one or more computing units, cause the computing unit(s) to execute the described method.

[0023] The invention also relates to a machine-readable data carrier and / or a downloadable product containing the computer program. A downloadable product is a digital product that can be transmitted over a data network, i.e., downloaded by a user of the data network, and which can be offered for immediate download, for example, in an online shop.

[0024] Such a computer program can be run on one or more computing units, for example, located in a cloud. The advantages mentioned for the method are achieved via such a computing unit operated in the cloud.

[0025] Embodiments of the invention are illustrated in the drawing and explained in more detail in the following description. It shows: Fig. 1 Representation of a motor vehicle with a device for automatic calibration according to an embodiment of the invention, and Fig. 2 Illustration of a method for determining the relative position of sensors according to an embodiment of the invention.

[0026] In Fig. Figure 1 shows a representation of a motor vehicle 10 with a device 14 for automatic calibration according to an exemplary embodiment of the invention. The device 14 comprises a plurality of sensors 18 with which a vehicle's surroundings can be monitored. For the sake of clarity, only two cameras 18a, a radar sensor 18b, and a lidar sensor 18c are shown in this exemplary embodiment. It is understood that significantly more sensors 18 are typically provided on the motor vehicle 10. Furthermore, the device comprises a control unit 22 connected to the sensors 18.

[0027] The sensors 18 and the control unit 22 comprise a dynamic measurement unit 26, via which dynamic values ​​can be determined at the respective sensor 18 or the control unit 22. In addition, a Bluetooth radio unit 30, for example, is provided in the sensors 18 and the control unit 22, via which a distance between the sensors 18 and the control unit 22 can be determined based on the signal strength. In particular, a distance between the sensors 18 and a reference point R P In the embodiment shown here, the reference point R P defined in the control unit 22. Instead of the Bluetooth radio unit 30, GNSS receiver modules can also be provided.

[0028] The sensors 18 and the control unit 22 each additionally comprise a communication unit 34, via which the measured acceleration values ​​and the relative distance are transmitted to the control unit 22. In the exemplary embodiment shown here, the sensors 18 are connected to the control unit 22 via a wired connection. However, it is also possible to transmit these values ​​wirelessly to the control unit 22. The sensors 18 and the control unit 22 each have a computing unit 38, via which the measured values ​​can be processed.

[0029] Although the measured values ​​are typically processed in the control unit 22, redundancy also allows these values ​​to be evaluated in the computing units 38 of the sensors 18, as well as in an external computing unit 38. The external computing unit 38 can be arranged in a cloud 42, which is connected to the control unit 22 via a mobile radio connection 46. Accordingly, it is possible to validate the calibration parameters determined by the control unit 22 via the external computing unit 38 or the computing units 38 of the sensors 18.

[0030] Fig. Figure 2 shows a representation of a method for determining the relative position of sensors 18 according to an embodiment of the invention. In a first method step A, a relative distance between the sensors 18 of the motor vehicle 10 and the reference point R Pby means of the Bluetooth radio unit 30. The distance can be determined based on the signal strength of the Bluetooth signal. In a further step B, the dynamic values ​​assigned to each sensor 18 are determined using the dynamic measurement unit 26 of each sensor 18. In a subsequent step C, the relative distance and the dynamic values ​​for each sensor 18 are transmitted to the computing unit 38 of the control unit 22. In the Fig. In the embodiment shown in Figure 1, these values ​​are transmitted via a wired connection.

[0031] In step E, within the computing unit 38 of the control unit 22, a relative orientation of the sensors 18 to each other and to the reference point R Pwithin the control unit 22. The dynamic values ​​determined by the sensors 18 depend solely on the orientation of the sensors 18 and the position in the motor vehicle 10. The determined dynamic values ​​are compared with each other accordingly. Since the dynamic values ​​are also measured in the control unit 22, an orientation and position of the sensors 18 relative to the reference point R P contained control unit 22.

[0032] Subsequently, in step F, calibration parameters are determined by converting the relative distances and orientation of the sensors 18 into a common coordinate system with the reference point R Pas the origin. The calibration parameters thus determined are stored in the computing unit 22 in a next step G. By storing these values, it is possible to monitor the temporal progression of a deviation. In a subsequent step H, the determined calibration parameters are compared with stored calibration parameters. The stored calibration parameters are values ​​that were determined at the beginning of the commissioning of the motor vehicle 10 and in which the sensors 18 have a predetermined orientation and a predetermined relative distance from one another.

[0033] Subsequently, a deviation ΔP K between the determined calibration parameters and the stored calibration parameters I. Then it is determined whether an actual deviation ΔP Kbetween the determined calibration parameters and the stored calibration parameters. If there is no deviation ΔP K If a deviation ΔP K If present, it is then checked whether the deviation ΔP K above a defined limit G W If the deviation ΔP K smaller than the limit G W If the deviation is not corrected, the deviation is compensated for by a software correction in a next step K. In other words, the sensor values ​​of the deviating sensor 18 are corrected accordingly.

[0034] If the deviation ΔP K however, should be greater than the limit G W , a predefined action is executed in a next step J. The action depends on the value of the deviation ΔP K , as well as for which sensor 18 the deviation ΔPK has been determined. The driver can be informed of an action. It is also possible that an automatic driving function dependent on this sensor 18 may be downgraded. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 102 29 334 B4

[0004] DE 10 2018 208 846 B4

[0005]

Claims

[1] Method for determining the relative position of sensors (18) of a motor vehicle (10) to a reference point (R P ), comprising the steps: - Determining (A) a relative distance between sensors (18) of the motor vehicle (10) among each other and / or to the reference point (R P ) via a wireless connection, - measuring (B) dynamic values ​​of the motor vehicle (10) for each sensor (18) by means of a dynamic measuring unit (26) assigned to each sensor (18), - transmitting (C) the relative distance and the dynamic values ​​for each sensor (18) to at least one computing unit (38), - Determining (E) a relative orientation of the sensors (18) to each other and / or to the reference point (R P ), by comparing the dynamic values ​​determined for each sensor (18), - Determining (F) calibration parameters by transforming the relative distances and orientations of the sensors (18) into a common coordinate system to the reference point (R P ), - comparison (H) of the determined calibration parameters of the sensors (18) with stored calibration parameters, - Determination (I) of a deviation (ΔP K ) between the determined calibration parameters and the stored calibration parameters, and - Perform (J) a predefined action if a deviation (ΔP K ) of at least one sensor (18) above a defined limit value (G W ) lies. [2] Method according to claim 1, characterized by that the comparison (H) of the calibration parameters and the determination of the deviation (ΔP K ) is carried out on a computing unit (38) common to all sensors (18). [3] Method according to claim 1 or 2, characterized bythat the comparison (H) of the calibration parameters and the determination of the deviation (ΔP K ) is carried out on an external computing unit (38) located outside the motor vehicle (10). [4] Method according to one of the preceding claims, characterized by that the comparison (H) of the calibration parameters and the determination of the deviation (ΔP K ) is carried out in a computing unit (38) of the respective sensor (18). [5] Method according to one of the preceding claims, characterized by that the relative distances are determined by measuring the signal strength of a radio signal. [6] Method according to one of the preceding claims, characterized by that the calibration parameters, the determined dynamic values ​​and the relative distances are saved (G). [7] Method according to one of the preceding claims, characterized by that deviations (ΔP K ) of the calibration parameters below the limit value (G W) can be compensated for by a software correction (K). [8] Method according to one of the preceding claims, characterized by that if a deviation (ΔP K ) of at least one sensor (18) above a defined limit value (G W ), the driver is informed. [9] Method according to one of the preceding claims, characterized by that if a deviation (ΔP K ) of at least one sensor (18) above a defined limit value (G W ), the driving function dependent on this sensor (18) is degraded. [10] Device (14) for automatic calibration, with which a method according to one of the preceding claims can be carried out, comprising: - sensors (18) with a dynamic measuring unit (26) for measuring dynamic values, means for determining a relative distance and a communication unit (34) for transmitting the measured values, and - Computing unit (38) for processing the measured values ​​of the sensors (18). [11] Device according to claim 10, characterized by that the computing unit (38) is provided in one of the sensors (18). [12] Device according to claim 10 or 11, characterized by that the means for determining the relative distance comprise a GNSS receiver and / or a radio unit (30). [13] A computer program product comprising machine-readable instructions which, when executed on one or more computing units (38), cause the computing unit(s) (38) to carry out a method according to any one of claims 1 to 9. [14] Machine-readable data carrier and / or download product with the computer program product according to claim 13. [15] Computing unit (38) equipped with the computer program product according to claim 13, and / or with the machine-readable data carrier and / or download product according to claim 14.

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