CHECKING THE POSITIONING OF AN ULTRASONIC SENSOR ON A VEHICLE

Abstract

A method for checking the positioning of an ultrasonic sensor installed in a mounting on the vehicle is disclosed. The method involves localizing a reference object in the detection region of the ultrasonic sensor, emitting at least one first ultrasonic pulse with a first ultrasonic frequency, receiving at least one first echo signal at the first ultrasonic frequency, emitting at least one second ultrasonic pulse with a second ultrasonic frequency, receiving at least one second echo signal at the second ultrasonic frequency, ascertaining the ratio of echo amplitudes of the reference object in the at least one first and second echo signal, and outputting an incorrect positioning of the ultrasonic sensor if the ratio of echo amplitudes in the reference object in the at least one first and second echo signal deviates from the ratio for a correct positioning of the ultrasonic sensor by at least one specified threshold.

Claims

1. A method for checking the positioning of an ultrasonic sensor on a vehicle, wherein the ultrasonic sensor is installed in a mounting bracket on the vehicle, said method comprising: localizing a reference object in the detection region of the ultrasonic sensor; emitting at least one first ultrasonic pulse with a first ultrasonic frequency by means of the ultrasonic sensor receiving at least one first echo signal at the first ultrasonic frequency by means of the ultrasonic sensor, emitting at least one second ultrasonic pulse with a second ultrasonic frequency by means of the ultrasonic sensor, receiving at least one second echo signal at the second ultrasonic frequency by means of the ultrasonic sensor, ascertaining the ratio of echo amplitudes of the reference object in the at least one first and second echo signal; and outputting an error in the positioning of the ultrasonic sensor if the ratio of echo amplitudes in the reference object in the at least one first and second echo signal deviates from the ratio for a correct positioning of the ultrasonic sensor by at least one specified threshold value.

2. The method as claimed in claim 1, wherein the localizing of a reference object in the detection region of the ultrasonic sensor comprises detecting a position of the reference object in the detection region of the ultrasonic sensor based on echo signals received using a plurality of ultrasonic sensors.

3. The method as claimed in claim 1, wherein the localizing of a reference object in the detection region of the ultrasonic sensor comprises emitting at least one focused ultrasonic pulse by means of the ultrasonic sensor having a narrow detection region and receiving at least one corresponding echo signal by means of the ultrasonic sensor, wherein the reference object is localized by finding an echo of the reference object contained in the at least one received echo signal in the detection region of the ultrasonic sensor.

4. The method as claimed in claim 1, wherein the localizing of a reference object in the detection region of the ultrasonic sensor comprises detecting a position of the reference object in the detection region of the ultrasonic sensor based on a detection of the surroundings using at least one environment sensor from an optical camera, a LiDAR-based environment sensor and a radar sensor.

5. The method as claimed in claim 1, the method positioning the reference object in a central region of the detection region of the ultrasonic sensor at an angle of approximately 0° relative to a central axis of the mounting bracket of the ultrasonic sensor.

6. The method as claimed in claim 1, wherein at least one of the first ultrasonic frequency and the second ultrasonic frequency is in a frequency range below a nominal frequency of the ultrasonic sensor, and the corresponding other ultrasonic frequency is above the first ultrasonic frequency, and above the nominal frequency.

7. The method as claimed in claim 1, further comprising: repeatedly emitting the at least one first ultrasonic pulse and/or the at least one second ultrasonic pulse; and repeatedly receiving the at least one first echo signal and/or the at least one second echo signal, and ascertaining the ratio of echo amplitudes of the reference object in the at least one first and second echo signal comprises ascertaining the ratio of the echo amplitudes of the reference object based on a plurality of first and second echo signals.

8. The method as claimed in claim 1, further comprising: determining a position of the reference object in the detection region of the ultrasonic sensor; and outputting an error in the positioning of the ultrasonic sensor comprises outputting an error in the positioning of the ultrasonic sensor if the ratio of echo amplitudes in the reference object in the at least one first and second echo signal deviates by at least one specified threshold value from the ratio for a correct positioning of the ultrasonic sensor, which is dependent on the position of the reference object in the detection region of the ultrasonic sensor.

9. The method as claimed in claim 1, further comprising: for determining a position of the reference object in the detection region of the ultrasonic sensor; and outputting an error in the positioning of the ultrasonic sensor comprises outputting an error in the positioning of the ultrasonic sensor if the ratio of the echo amplitudes of the reference object in the at least one first and second echo signal deviates from the ratio for a correct positioning of the ultrasonic sensor by at least one predetermined threshold value, which is dependent on the position of the reference object in the detection region of the ultrasonic sensor.

10. A sensor assembly comprising: at least one ultrasonic sensor; and a control unit, which is connected via a data link to the at least one ultrasonic sensor, wherein the at least one ultrasonic sensor is installed in a mounting bracket on the vehicle, wherein the sensor assembly is configured to perform the method for checking the positioning of an ultrasonic sensor on a vehicle as claimed in claim 1.

Description

[0042] The invention is explained in more detail below with reference to the attached drawing based on preferred embodiments. The features shown may each represent an aspect of the invention both individually and in combination. Features of different exemplary embodiments can be transferred from one exemplary embodiment to another.

[0043] In the figures:

[0044] FIG. 1 shows a schematic view of an ultrasonic sensor according to a first, preferred embodiment in a mounting bracket, wherein the ultrasonic sensor is correctly positioned and engaged in the mounting bracket,

[0045] FIG. 2 shows a schematic view of the ultrasonic sensor in the mounting bracket according to the illustration in FIG. 1, wherein the ultrasonic sensor is positioned incorrectly and not fully engaged in the mounting bracket,

[0046] FIG. 3 shows a diagram of the detection regions of the ultrasonic sensor which is correctly positioned and engaged in the mounting bracket in accordance with FIG. 1, and of the ultrasonic sensor which is incorrectly positioned in the mounting bracket in accordance with FIG. 2 and is accordingly not fully engaged in it, at a medium ultrasonic frequency,

[0047] FIG. 4 shows a diagram of the detection regions of the ultrasonic sensor which is correctly positioned and engaged in the mounting bracket in accordance with FIG. 1, and of the ultrasonic sensor which is incorrectly positioned in the mounting bracket in accordance with FIG. 2 and is therefore not fully engaged in it, at a high, first ultrasonic frequency,

[0048] FIG. 5 shows a diagram of the detection regions of the ultrasonic sensor which is correctly positioned and engaged in the mounting bracket in accordance with FIG. 1, and of the ultrasonic sensor which is incorrectly positioned in the mounting bracket in accordance with FIG. 2 and is therefore not fully engaged in it, at a low, second ultrasonic frequency,

[0049] FIG. 6 shows a graph of ratios of echo amplitudes of a reference object in a first and second echo signal with the first and second ultrasonic frequency for the ultrasonic sensor which is correctly positioned in the mounting bracket and engaged in accordance with FIG. 1, and for the ultrasonic sensor which is incorrectly positioned in the mounting bracket in accordance with FIG. 2 and not fully engaged in it, as a function of an angular position of the reference object,

[0050] FIG. 7 shows a flow diagram of a first method for checking the positioning of the ultrasonic sensor from FIGS. 1 and 2 on a vehicle, wherein the ultrasonic sensor is installed in a mounting bracket on the vehicle,

[0051] FIG. 8 shows a flow diagram of a second method for checking the positioning of the ultrasonic sensor from FIGS. 1 and 2 on a vehicle, wherein the ultrasonic sensor is installed in a mounting bracket on the vehicle, and

[0052] FIG. 9 shows a schematic representation of a vehicle having a sensor assembly with a plurality of ultrasonic sensors from FIGS. 1 and 2 and with a control unit connected to the plurality of ultrasonic sensors.

[0053] FIG. 1 shows an ultrasonic sensor 10 according to a first, preferred embodiment.

[0054] The ultrasonic sensor 10 comprises a sensor housing 12, on which two latching projections 14 are formed diametrically opposite each other. The ultrasonic sensor 10 additionally comprises a sensor head, which is not visible in the illustration in FIG. 1, having an ultrasonic diaphragm. A control and evaluation electronics is arranged within the sensor housing 12. The sensor housing 12 is closed with a cover 16. From a proximal end of the sensor housing 12 in FIG. 1, a plug socket 18 protrudes in the radial direction. It is understood that in other embodiments, the plug socket 18 can also protrude from the proximal end of the sensor housing at other angles.

[0055] The ultrasonic sensor 10 is accommodated in a mounting bracket 20. For this purpose, the mounting bracket 20 comprises two latching arms 22 with latch openings, not shown here. The latching arms 22 can spring in the radial direction and are used to hold and secure the ultrasonic sensor 10. When the ultrasonic sensor 10 is correctly positioned in the mounting bracket 20, both latching projections 14 engage in the corresponding openings of the latching arms 22 and the ultrasonic sensor 10 is both correctly positioned and securely held in the sensor mounting bracket 20.

[0056] The ultrasonic sensor 10 is part of a sensor arrangement 30 with a plurality of ultrasonic sensors 10 and a control unit 32, which is connected via a data connection 34 to the ultrasonic sensors 10. In principle, the control unit 32 can be any desired data processing device. In the automotive sector, so-called embedded systems are often used. The term ECU (Electronic Control Unit) is used for such control units 32. The data link 34 can comprise a bus, for example in the form of a DSI3 bus, CAN bus, FlexRay or as a proprietary implementation. In principle, however, a direct data link 34 between the control unit 32 and each of the ultrasonic sensors 10 is also possible.

[0057] The ultrasonic sensors 10 of the sensor assembly 30 in this exemplary embodiment are mounted on a rear side and a front side of a vehicle 36, as shown in FIG. 9. For this purpose, the mounting brackets 20 of the ultrasonic sensors 10 are fixed to the rear side and the front side of the vehicle 36, for example on a front or rear fender of the vehicle 36.

[0058] FIG. 2 also shows the ultrasonic sensor 10 from FIG. 1 of the first, preferred embodiment.

[0059] In contrast to the illustration in FIG. 1, however, only one of the two latching projections 14 of the ultrasonic sensor 10 engages in the corresponding opening of one of the latching arms 22. As a result, the ultrasonic sensor 10 is not correctly positioned. The consequence of this is that the ultrasonic sensor 10 is supposedly securely fixed in the mounting bracket 20, but in reality it is tilted and thus not properly positioned in the mounting bracket 20. Such an improper positioning of the ultrasonic sensor 10 in the mounting bracket 20 causes position and/or angle deviations of a sensor axis with respect to a central axis 42 of the mounting bracket 20, which can lead to incorrect functioning of the ultrasonic sensor 10 and, in addition, to malfunctions of driving assistance systems that use this ultrasonic sensor 10.

[0060] In order to be able to detect such cases of incorrect positioning, a first method for checking a positioning of the ultrasonic sensor 10 in the mounting bracket 20 on the vehicle 36, as shown in FIG. 7, is described below. The method is carried out under the control of the control unit 32. The control unit 32 can individually control each of the ultrasonic sensors 10 of the sensor assembly 30 via the data link 34 in order to carry out the method described below. The method is described with additional reference to FIGS. 3 to 6.

[0061] The method begins with step S100, which involves localizing a reference object in the detection region 40 of the ultrasonic sensor 10. The detection region 40 here defines a region in which an echo of the reference object can be received for a first and a second ultrasonic frequency. The detection region 40 is defined in relation to a correct positioning of the ultrasonic sensor 10 with its sensor axis corresponding to a central axis 42 of the mounting bracket 20, which also defines a correct positioning of the ultrasonic sensor 10. For a nominal frequency, i.e. in a medium frequency range, FIG. 3 accordingly shows detection regions 40a, 40b for a correct positioning of the ultrasonic sensor 10 in the mounting bracket 20, as shown in FIG. 1, and for an incorrect positioning of the ultrasonic sensor 10 in the mounting bracket 20, as shown in FIG. 2.

[0062] Localizing a reference object in the detection region 40 of the ultrasonic sensor 10 involves detecting a suitable reference object in the detection region 40. The object must therefore be suitable as a reference object and be located in the detection region 40 of the ultrasonic sensor 10.

[0063] For this purpose, a positioning of the reference object in the detection region 40 of the ultrasonic sensor 10 is carried out based on echo signals received with a plurality of ultrasonic sensors 10. For example, ultrasonic signals are automatically emitted from all ultrasonic sensors 10 located on the front of the vehicle 36 and echo signals based on them are received in order to carry out the method for an ultrasonic sensor 10 on the front of the vehicle 36. Distance information with respect to the reference object is detected in the echo signal and processed in order to detect the position of the reference object. For example, known methods of multilateration, in particular trilateration, are used to detect the position of the reference object in the detection region 40 of the ultrasonic sensor 10. In addition, based on the echo signals received, it is ascertained whether the object is suitable as a reference object. For this purpose, a height estimation for the object is carried out in a known manner based on the received echo signals. The reference object is preferably located in the same height range as the ultrasonic sensor 10. In addition, based on the received echo signals, a detection of walls, for example, is carried out in a known manner in order to exclude such objects. The position of the reference object is determined relative to the ultrasonic sensor 10 as an angle in a horizontal plane along with a distance.

[0064] Step S110 relates to the positioning of the reference object in a central region of the detection region 40 of the ultrasonic sensor 10, preferably in an angular range of +/−15°, further preferably in an angular range of +/−10°, and particularly preferably in an angular range of +/−5°, in particular at an angle of approximately 0° relative to a central axis 42 of the mounting bracket 20, which corresponds to a sensor axis of the ultrasonic sensor 10 when the ultrasonic sensor 10 is correctly positioned.

[0065] Based on the position of the reference object determined in step S100, an instruction to move the vehicle 36 and/or the reference object is output in order to position the reference object relative to the vehicle 36 and thus relative to the ultrasonic sensor 10. The reference object is therefore preferably positioned in conjunction with the localization of the reference object in the detection region 40 of the ultrasonic sensor 10. Accordingly, the positioning is checked again in a further step S100, and if necessary, the positioning of the reference object is also repeated until the reference object has a desired positioning in the central region of the detection region 40. Preferably, the vehicle 36 autonomously carries out the positioning relative to the reference object in order to position the reference object in the central region of the detection region 40.

[0066] Step S120 relates to emitting a first ultrasonic pulse with a first ultrasonic frequency by means of the ultrasonic sensor 10. The first ultrasonic frequency here is a frequency of approximately 59 kHz. The ultrasonic sensor 10, for example, has a nominal frequency here of 52 kHz, so that the first ultrasonic frequency is above the nominal frequency.

[0067] Step S130 relates to receiving a first echo signal at the first ultrasonic frequency by means of the ultrasonic sensor 10. Detection regions 40a, 40b corresponding to a correct positioning of the ultrasonic sensor 10 in the mounting bracket 20, as shown in FIG. 1, and to an incorrect positioning of the ultrasonic sensor 10 in the mounting bracket 20, as shown in FIG. 2, are shown in FIG. 4. Raw sensor data is received as the first echo signal. The raw sensor data is transmitted from the ultrasonic sensor 10 to the control unit 32.

[0068] Step S140 relates to emitting a second ultrasonic pulse with a second ultrasonic frequency by means of the ultrasonic sensor 10. The second ultrasonic frequency here is a frequency of approximately 46 kHz and is therefore below the nominal frequency.

[0069] Step S150 relates to receiving a second echo signal at the second ultrasonic frequency by means of the ultrasonic sensor 10. Detection regions 40a, 40b corresponding to a correct positioning of the ultrasonic sensor 10 in the mounting bracket 20, as shown in FIG. 1, and to an incorrect positioning of the ultrasonic sensor 10 in the mounting bracket 20, as shown in FIG. 2, are shown in FIG. 5. Sensor raw data, which is transmitted from the ultrasonic sensor 10 to the control unit 32, is also received as the second echo signal.

[0070] Step S160 involves determining a ratio of echo amplitudes of the reference object in the first and second echo signals. Corresponding ratios 44 are shown in FIG. 6, wherein a ratio 44a for a correct positioning of the ultrasonic sensor 10 in the mounting bracket 20, as shown in FIG. 1, and a ratio 44b for an incorrect positioning of the ultrasonic sensor 10 in the mounting bracket 20, as shown in FIG. 2, are given.

[0071] Appropriate detection and processing of levels of echo amplitudes of the reference object in the first and second echo signal is carried out. The processing takes place in the control unit 32.

[0072] Step S170 relates to outputting an error in the positioning of the ultrasonic sensor 10 if the ratio 44 of the echo amplitudes of the reference object in the first and second echo signal deviates from the ratio for a correct positioning of the ultrasonic sensor 10 by at least one specified threshold value. The output is provided by the control unit 32.

[0073] An error in the positioning of the ultrasonic sensor 10 is output if the ratio 44 of the echo amplitudes of the reference object in the first and second echo signal deviates from the ratio for a correct positioning of the ultrasonic sensor 10 by at least one predetermined threshold value, which is dependent on the position of the reference object in the detection region 40 of the ultrasonic sensor 10. As shown in FIG. 6, the curves of the ratios of the echo amplitudes are each dependent on the position of the reference object in the detection region 40 that was determined in step S100. This results in a position-dependent evaluation of the ratio of the echo amplitudes of the reference object in the received echo signals.

[0074] A second method for checking a positioning of the ultrasonic sensor 10 in the mounting bracket 20 on the vehicle 36, as shown in FIG. 8, is described below. The method is also carried out with the sensor assembly 30 described above. The method is carried out under the control of the control unit 32. The control unit 32 can individually control each of the ultrasonic sensors 10 of the sensor assembly 30 via the data link 34 in order to carry out the method described below. The second method is partly the same as the first method, so that essentially only differences between the two methods are described here.

[0075] The second method begins, as previously described with reference to the first method, with step S120 which relates to an emission of a first ultrasonic pulse with a first ultrasonic frequency by means of the ultrasonic sensor 10. The first ultrasonic frequency here is also a frequency of approximately 59 kHz. The ultrasonic sensor 10 here, by way of example, has a nominal frequency of 52 kHz, so that the first ultrasonic frequency is above the nominal frequency.

[0076] Step S130 relates to receiving a first echo signal at the first ultrasonic frequency by means of the ultrasonic sensor 10. Detection regions 40a, 40b corresponding to a correct positioning of the ultrasonic sensor 10 in the mounting bracket 20, as shown in FIG. 1, and to an incorrect positioning of the ultrasonic sensor 10 in the mounting bracket 20, as shown in FIG. 2, are shown in FIG. 4. Raw sensor data is received as the first echo signal. The raw sensor data is transmitted from the ultrasonic sensor 10 to the control unit 32.

[0077] Step S135 involves localizing a reference object in the detection region 40 of the ultrasonic sensor 10. The detection region 40 here also defines a region in which an echo of the reference object can be received for a first and a second ultrasonic frequency. The detection region 40 is defined in relation to a correct positioning of the ultrasonic sensor 10 with its sensor axis corresponding to a central axis of the mounting bracket 20, which defines the correct positioning of the ultrasonic sensor 10.

[0078] Localizing the reference object in the detection region 40 of the ultrasonic sensor 10 involves detecting a suitable reference object in the detection region 40.

[0079] Correspondingly, the reference object is determined in the first echo signal received. The first echo signal received is based on the emission of the first ultrasonic pulse with the high frequency of 59 kHz, which means that the first ultrasonic pulse is a focused ultrasonic pulse so that a narrow detection region 40 is obtained for receiving the first echo signal with the ultrasonic sensor 10.

[0080] If an echo of the reference object is contained in the first echo signal, this will be localized in the detection region 40 of the ultrasonic sensor 10. The object has a suitable positioning as a reference object, which will also allow it to be detected in the wider detection region 40 for lower frequencies.

[0081] Step S140 relates to emitting a second ultrasonic pulse with a second ultrasonic frequency by means of the ultrasonic sensor 10. The second ultrasonic frequency here is a frequency of approximately 46 kHz and is therefore below the nominal frequency of the ultrasonic sensor 10.

[0082] Step S150 relates to receiving a second echo signal at the second ultrasonic frequency by means of the ultrasonic sensor 10. Detection regions 40a, 40b corresponding to a correct positioning of the ultrasonic sensor 10 in the mounting bracket 20, as shown in FIG. 1, and to an incorrect positioning of the ultrasonic sensor 10 in the mounting bracket 20, as shown in FIG. 2, are shown in FIG. 5. Sensor raw data, which is transmitted from the ultrasonic sensor 10 to the control unit 32, is also received as the second echo signal.

[0083] Step S160 involves determining a ratio of echo amplitudes of the reference object in the first and second echo signals. Corresponding ratios 44 are shown in FIG. 6, wherein a ratio 44a for a correct positioning of the ultrasonic sensor 10 in the mounting bracket 20, as shown in FIG. 1, and a ratio 44b for an incorrect positioning of the ultrasonic sensor 10 in the mounting bracket 20, as shown in FIG. 2, are given.

[0084] Appropriate detection and processing of levels of echo amplitudes of the reference object in the first and second echo signal is carried out.

[0085] Step S170 relates to outputting an error in the positioning of the ultrasonic sensor 10 if the ratio 44 of the echo amplitudes of the reference object in the first and second echo signal deviates from the ratio for a correct positioning of the ultrasonic sensor 10 by at least one specified threshold value. In the second method, the threshold value is independent of an exact position of the reference object since the exact position was not ascertained, unlike in the 1st method.

[0086] In the second method, shown in FIG. 8, a dedicated detection mode can be omitted if the ultrasonic sensors 10 emit alternately at a high frequency and a low frequency in normal operation. This helps to avoid dead times in normal operation. This also allows for continuous checking.

LIST OF REFERENCE SIGNS

[0087] 10 ultrasonic sensor [0088] 12 sensor housing [0089] 14 latching projection [0090] 16 cover [0091] 18 plug socket [0092] 20 mounting bracket [0093] 22 latching arm [0094] 30 sensor assembly [0095] 32 control unit [0096] 34 data link [0097] 36 vehicle [0098] 40 detection region [0099] 40a detection region correct positioning [0100] 40b detection region incorrect positioning [0101] 42 central axis [0102] 44 ratio of echo amplitudes [0103] 44a ratio of echo amplitudes correct positioning [0104] 44b ratio of echo amplitudes incorrect positioning