METHOD FOR DETERMINING SOILING OF A FIRST ULTRASONIC SENSOR, COMPUTER PROGRAM PRODUCT, COMPUTER-READABLE STORAGE MEDIUM, ULTRASONIC SENSOR APPARATUS, AND ASSISTANCE SYSTEM

Abstract

A method for determining soiling of a first ultrasonic sensor of a motor vehicle in which a first ultrasonic signal is emitted by means of the first ultrasonic sensor and the first reflected ultrasonic signal is received by means of the first ultrasonic sensor, and in which a second ultrasonic signal that differs from the first ultrasonic signal is emitted into the environment substantially at the same time as the first ultrasonic signal by a second ultrasonic sensor, wherein the second ultrasonic signal is received by means of the first ultrasonic sensor and the first received ultrasonic signal is compared with the second received ultrasonic signal by an electronic computing device, and the soiling is determined on the basis of the comparison.

Claims

1. A method for determining soiling of a first ultrasonic sensor of an ultrasonic sensor apparatus of an assistance system of a motor vehicle, the method comprising: transmitting, by the first ultrasonic sensor, a first ultrasonic signal into surroundings of the motor vehicle; receiving the first ultrasonic signal, reflected in the surroundings, by the first ultrasonic sensor, transmitting, by a second ultrasonic sensor of the ultrasonic sensor apparatus, a second ultrasonic signal, which is different than the first ultrasonic signal, into the surroundings essentially simultaneously with the first ultrasonic signal, wherein the first ultrasonic sensor is used to receive the second ultrasonic signal reflected in the surroundings, and comparing the first received ultrasonic signal with the second received ultrasonic signal using an electronic computing device of the ultrasonic sensor apparatus wherein the comparison is taken as a basis for the soiling to be determined by the electronic computing device.

2. The method as claimed in claim 1, wherein the first received ultrasonic signal is taken as a basis for a first reception curve, and the second received ultrasonic signal is taken as a basis for a second reception curve, to be generated by means of the electronic computing device, and the first reception curve is compared with the second reception curve.

3. The method as claimed in claim 1, wherein no soiling of the first ultrasonic sensor is determined if the first received ultrasonic signal differs from the second received ultrasonic signal.

4. The method as claimed in claim 1, wherein soiling of the first ultrasonic sensor is determined if the first received ultrasonic signal matches the second received ultrasonic signal.

5. The method as claimed in claim 1, wherein the first ultrasonic signal is transmitted in a different frequency band than the second ultrasonic signal.

6. The method as claimed in claim 1, wherein the first ultrasonic signal is transmitted with a different phase modulation than the second ultrasonic signal.

7. The method as claimed in claim 1, wherein the first ultrasonic signal is transmitted with a different frequency modulation than the second ultrasonic signal.

8. The method as claimed in claim 7, wherein the first ultrasonic signal is transmitted with a frequency modulation for which the frequency increases over time (t), and the second ultrasonic signal is transmitted with a frequency modulation for which the frequency decreases over time (t), or the first ultrasonic signal is transmitted with a frequency modulation for which the frequency decreases over time (t), and the second ultrasonic signal is transmitted with a frequency modulation for which the frequency increases over time (t).

9. The method as claimed in claim 1, wherein a sensor noise of the first ultrasonic sensor is taken into account when determining the soiling.

10. The method as claimed in claim 1, wherein a correlation filter of the first ultrasonic sensor is used to extract the first ultrasonic signal and the second ultrasonic signal from one another.

11. The method as claimed in claim 1, wherein the determination of the soiling is carried out before the start of a journey.

12. A computer program product having program code means that are stored in a computer-readable storage medium in order to carry out the method as claimed in claim 1 when the computer program product is executed on a processor of an electronic computing device.

13. A computer-readable storage medium having a computer program product as claimed in claim 12.

14. An ultrasonic sensor apparatus for a motor vehicle, having at least one first ultrasonic sensor, having a second ultrasonic sensor and having an electronic computing device, the ultrasonic sensor apparatus being designed to carry out a method as claimed in claim 1.

15. An assistance system having an ultrasonic sensor apparatus as claimed in claim 14.

Description

[0033] The invention will now be explained in more detail using preferred exemplary embodiments and with reference to the accompanying drawings,

[0034] in which:

[0035] FIG. 1 shows a schematic plan view of an embodiment of a motor vehicle with an embodiment of an assistance system;

[0036] FIG. 2 shows a schematic graph of received ultrasonic signals; and

[0037] FIG. 3 shows a further schematic graph of received ultrasonic signals.

[0038] In the figures, identical or functionally identical elements are provided with the same reference signs.

[0039] FIG. 1 shows a schematic plan view of an embodiment of a motor vehicle 1 with an embodiment of an assistance system 2. The assistance system 2 can be embodied as a parking assistance system 2, for example. The motor vehicle 1 can be in at least semi-autonomous, in particular fully autonomous, form. The motor vehicle 1 or the assistance system 2 has an ultrasonic sensor apparatus 3. The ultrasonic sensor apparatus 3 has two ultrasonic sensors 4, 5 in the present exemplary embodiment. It should be mentioned at this point that this is purely illustrative. The ultrasonic sensor apparatus 3 can also have further ultrasonic sensors 4, 5. In the present exemplary embodiment, the ultrasonic sensor apparatus 3 is formed on a front part of the motor vehicle 1. It goes without saying that the ultrasonic sensor apparatus 3 can also be formed, for example, on a rear end and/or on a side of the motor vehicle 1.

[0040] In order to be able to carry out the method according to the invention, the ultrasonic sensor apparatus 3 in particular also has an electronic computing device 6. The electronic computing device 6 in turn has, for example, a computer-readable storage medium and a computer program product, which is not shown in the present case.

[0041] The method for determining soiling of the first ultrasonic sensor 4 of the ultrasonic sensor apparatus 3 of the assistance system 2 of the motor vehicle 1 involves the first ultrasonic sensor 4 being used to transmit a first ultrasonic signal 7 into surroundings 8 of the motor vehicle 1 and the first ultrasonic signal 7, reflected in the surroundings 8, being received by means of the first ultrasonic sensor 4, and a second ultrasonic sensor 5 being used to transmit a second ultrasonic signal 9, which is different than the first ultrasonic signal 7, into the surroundings 8 essentially simultaneously with the first ultrasonic signal 7.

[0042] There is provision for the first ultrasonic sensor 4 to be used to receive the second ultrasonic signal 9 reflected in the surroundings 8, and for the first received ultrasonic signal 7 to be compared with the second received ultrasonic signal 9 by means of the electronic computing device 6 of the ultrasonic sensor apparatus 3 and for the comparison to be taken as a basis for the soiling to be determined by means of the electronic computing device 6.

[0043] In particular, there can be provision for the first ultrasonic signal 7 to be transmitted in a different frequency band than the second ultrasonic signal 9. Alternatively or additionally, the first ultrasonic signal 7 can be transmitted with a different phase modulation than the second ultrasonic signal 9. Alternatively or additionally again, the first ultrasonic signal 7 can be transmitted with a different frequency modulation than the second ultrasonic signal 9. There can also be provision for the first ultrasonic signal 7 to be transmitted with a frequency modulation for which the frequency increases over time t (FIG. 2), and for the second ultrasonic signal 9 to be transmitted with a frequency modulation for which the frequency decreases over time t, or for the first ultrasonic signal 7 to be transmitted with a frequency modulation for which the frequency decreases over time t, and for the second ultrasonic signal to be transmitted with a frequency modulation for which the frequency increases over time t. An ultrasonic signal 7, 9 for which the frequency increases over time is referred to in particular as a chirp-up. An ultrasonic signal 7, 9 for which the frequency decreases over time t is referred to in particular as a chirp-down.

[0044] Furthermore, there can in particular be provision for the determination of the soiling to be carried out before the start of a journey.

[0045] FIG. 2 shows a schematic graph of received different ultrasonic signals 7, 9. In the present case, the ultrasonic signals 7, 9 are shown in particular as reception curves 10, 11. The time t is plotted on the abscissa and the amplitude on the ordinate. In particular, FIG. 2 shows that the reception curves 10, 11 have applicable echoes, this being shown by applicable different amplitudes for the different times t.

[0046] In particular, the present case shows that the first received ultrasonic signal 7 is taken as a basis for a first reception curve 10, and the second received ultrasonic signal 9 is taken as a basis for a second reception curve 11, to be generated by means of the electronic computing device 6, and the first reception curve 10 is compared with the second reception curve 11. FIG. 2 shows in particular that the ultrasonic signals 7, 9 or the reception curves 10, 11 differ from one another. In particular, no soiling of the first ultrasonic sensor 4 can then be determined if the first received ultrasonic signal 7 differs from the second received ultrasonic signal 9.

[0047] As shown in the present case, the ultrasonic signals 7, 9 can be extracted using a correlation filter. The first ultrasonic signal 7 can thus be reliably distinguished from the second ultrasonic signal 9.

[0048] FIG. 2 thus shows in particular so-called envelopes, the first reception curve 10 representing a direct measurement by the first ultrasonic sensor 4 of its own transmitted first ultrasonic signal 7 and the second reception curve 11 representing the indirect measurement of the second ultrasonic signal 9 of the second ultrasonic sensor 5. Due to the different reflections, for example from a ground, the two reception curves 10, 11 differ significantly from one another.

[0049] FIG. 3 shows a further schematic graph relating to the received ultrasonic signals 7, 9. FIG. 3 again shows the first reception curve 10 and the second reception curve 11. In the present case, it can be seen in particular that it is essentially possible to record a match between the first reception curve 10 and the second reception curve 11, or the first ultrasonic signal 7 and the second ultrasonic signal 9. In particular soiling of the first ultrasonic sensor 4 can be determined if the first received ultrasonic signal 7 matches the second ultrasonic signal 9. In particular, FIG. 3 shows that the first ultrasonic sensor 4 is not able to detect anything due to the soiling, this being characterized in particular by the fact that the first reception curve 10 and the second reception curve 11 no longer contain any echoes and are essentially the same.

[0050] In particular, it can be seen over time t that, in particular at a later reception time, background noise is indicated, which is amplified over distance. In particular, there can now be provision for the sensor noise of the first ultrasonic sensor 4 to be taken into account when determining the soiling.

[0051] The proposed method can be used in particular to obtain the soiling within a single measurement cycle. In particular, no additional configuration of the ultrasonic sensor apparatus 3 is necessary. Furthermore, no functions of the ultrasonic sensor apparatus 3, for example the parking function, need to be interrupted. The present case also involves a simple method, for example as a result of comparing a floating average or subtracting the two reception curves 10, 11 or other very simple comparison methods. Furthermore, the method according to the invention is independent of the type of modulation.

[0052] In particular, FIGS. 1 to 3 show blindness detection for the first ultrasonic sensor 4 by means of a channel comparison.