METHOD FOR CHARACTERISING AN OBJECT IN AN ENVIRONMENT OF A MOTOR VEHICLE

Abstract

The present disclosure present disclosure relates to a method for characterizing an object in an environment of a motor vehicle by an assistance system of the motor vehicle, in which method the motor vehicle is moved relative to the object and ultrasonic signals are emitted with an ultrasonic sensor of the assistance system. Echoes of the ultrasonic signals reflected by the object are received, wherein, by a control device, respective amplitudes of the received echoes are ascertained, and a classification of a height of the object is determined based on the amplitudes. present disclosure The classification of the height of the object is determined based on a determined first change in amplitude by comparing a first amplitude of a first echo with a second amplitude of a second echo received after the first echo. present disclosure An assistance system is disclosed having an ultrasonic sensor and a control device designed to carry out such a method.

Claims

1. A method for characterizing an object in an environment of a motor vehicle by an assistance system of the motor vehicle, in which method the motor vehicle is moved relative to the object and ultrasonic signals are emitted with an ultrasonic sensor of the assistance system, wherein echoes of the ultrasonic signals reflected by the object are received, wherein, by a control device, respective amplitudes of the received echoes are ascertained and a classification of a height of the object is determined based on the amplitudes, wherein the classification of the height of the object is determined on the basis of a determined first change in amplitude by comparing a first amplitude of a first echo with a second amplitude of a second echo which was received after the first echo.

2. The method according to claim 1, wherein the first echo and the second echo are temporally successive echoes.

3. The method according to claim 1, wherein the object is located in the vicinity of the motor vehicle, when the motor vehicle approaches the object, the object is classified as low if an amplitude decrease over a course of time is determined as the first change in amplitude, and the object is classified as high if an amplitude increase over the course of time is determined as the first change in amplitude.

4. The method according to claim 1, wherein the classification of the height of the object is determined on the basis of a comparison of the first change in amplitude with a second change in amplitude, and the second change in amplitude is determined by comparing a third amplitude of a third echo which was received after the second echo with the second amplitude of the second echo or with a fourth amplitude of a fourth echo which was received after the second echo and before the third echo.

5. The methods according to claim 4, wherein when the motor vehicle approaches the object, the object is classified as low if an amplitude increase over the course of time is determined as the first change in amplitude and an amplitude decrease over the course of time is determined as the second change in amplitude.

6. The method according to claim 4, wherein the object is located in the vicinity of the motor vehicle, when the motor vehicle approaches the object, the object is classified as low if an amplitude decrease over the course of time is determined in each case as the first change in amplitude and as the second change in amplitude, and if the second change in amplitude is additionally greater than the first change in amplitude.

7. The method according to claim 4, wherein the object is located in the vicinity of the motor vehicle, when the motor vehicle approaches the object, the object is classified as high if an amplitude increase over the course of time is in each case determined as the first change in amplitude and as the second change in amplitude, and if the second change in amplitude is additionally greater than the first change in amplitude.

8. The method according to claim 1, wherein the classification of the height of the object is determined when the first change in amplitude, in terms of an amount, additionally lies above a predefined threshold.

9. The method according to claim 8, wherein the threshold is previously ascertained as at least one of a function of a current speed of the motor vehicle, a temperature in the environment of the motor vehicle, a humidity in the environment of the motor vehicle, or an installation height of the ultrasonic sensor on the motor vehicle.

10. The method according to claim 1, wherein the comparison of the amplitudes is based on at least one of a difference or a relationship of the amplitudes.

11. The method according to claim 4, wherein the comparison of the changes in amplitude is based on at least one of a difference or a relationship of the changes in amplitude.

12. The method according to claim 1, wherein the method is utilized during at least one of an assisted, semi-automatic, or automatic parking method.

13. The method according to claim 1, wherein the classification of the height of the object is exclusively based on sensor data of the ultrasonic sensor.

14. An assistance system having an ultrasonic sensor and a control device which is configured to carry out a method according to claim 1.

15. The method according to claim 3, wherein the object is located in the vicinity of the motor vehicle at a distance of up to two meters from the ultrasonic sensor of the motor vehicle.

16. The method according to claim 6, wherein the object is located in the vicinity of the motor vehicle at a distance of up to two meters from the ultrasonic sensor of the motor vehicle.

17. An assistance system for a vehicle, comprising: a controller configured to receive echoes from at least one ultrasonic sensor that are reflected by an object in an environment of a vehicle, ascertain amplitudes of amplitudes of the received echoes, determine a classification of a height of the object based upon the ascertained amplitudes, wherein the classification of the height of the object is determined based on a determined first change in amplitude by comparing a first amplitude of a first echo of the received echoes with a second amplitude of a second echo of the received echoes which was received after the first echo.

18. The assistance system of claim 17, wherein the first echo and the second echo are temporally successive echoes.

19. The assistance system of claim 17, wherein the object is located in the vicinity of the motor vehicle, and when the motor vehicle approaches the object, the object is classified as low if an amplitude decrease over a course of time is determined as the first change in amplitude, and the object is classified as high if an amplitude increase over the course of time is determined as the first change in amplitude.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Exemplary embodiments of the present disclosure are explained in greater detail below with reference to a drawing, wherein:

[0038] FIG. 1 shows a radiation diagram which depicts a radiation pattern of an ultrasonic sensor as a function of the elevation angle,

[0039] FIG. 2 shows a diagram which depicts the elevation angle as a function of the distance of the ultrasonic sensor according to FIG. 1 from an object, and

[0040] FIG. 3 show a flow chart of a method for characterizing an object in an environment of a motor vehicle.

DETAILED DESCRIPTION

[0041] Parts corresponding to one another are always provided with the same reference numerals in all of the figures.

[0042] A radiation diagram is shown in FIG. 1, which depicts a radiation pattern 1 of an ultrasonic sensor as a function of the elevation angle. It is obvious from this that the radiation pattern 1 of the ultrasonic sensor is a function of the elevation angle, that is to say that the power of an ultrasonic signal, which is emitted by an ultrasonic sensor to an object in the capturing range, depends on the elevation angle.

[0043] If an object is located at an elevation angle of 90, i.e., at least at an installation height of the ultrasonic sensor in a motor vehicle, then the elevation angle does not change when the motor vehicle, more precisely the ultrasonic sensor, approaches the object. The power or, in other words, the amplitude of the reflected ultrasonic signal or echo only depends on the distance between the ultrasonic sensor and the object. Therefore, the amplitude of the reflected ultrasonic signal gradually increases when the motor vehicle or the ultrasonic sensor approaches a tall object.

[0044] In the case of an object which has a height which is less than the installation height of the ultrasonic sensor in the motor vehicle, the elevation angle and, therefore, the power or amplitude of the reflected ultrasonic signal consequently change as a function of the distance between the motor vehicle or the ultrasonic sensor and the object. When the motor vehicle or ultrasonic sensor approaches the object, the elevation angle gradually reduces until it reaches approximately 0 as soon as the ultrasonic sensor is located directly on the object.

[0045] FIG. 2 shows a diagram which depicts the elevation angle as a function of the distance of the ultrasonic sensor according to FIG. 1 from an object. The object has a height which is 40 cm less than the installation height of the ultrasonic sensor in the motor vehicle. The object is configured here as a curb.

[0046] It is obvious from the diagram that when the object is not yet located in the vicinity of the motor vehicle, in particular at a distance of greater than two meters from the ultrasonic sensor of the motor vehicle, the elevation angle is approximately 90. In this range, the power, more precisely the amplitude of the reflected ultrasonic signal, consequently substantially depends merely on the distance between the object and the ultrasonic sensor. The amplitude of the reflected ultrasonic signal increases when the motor vehicle or the ultrasonic sensor approaches such an object, that is to say when the distance between the object and the ultrasonic sensor reduces.

[0047] If the motor vehicle or the ultrasonic sensor continues to approach the object and the object is then located in the vicinity of the motor vehicle, in particular at a distance of less than two meters from the ultrasonic sensor of the motor vehicle, the elevation angle gradually reduces noticeably as the motor vehicle or ultrasonic sensor continues to approach the object. This leads to the amplitude of the reflected ultrasonic signal also gradually decreasing when the motor vehicle or ultrasonic sensor continues to approach the object. It is true that the amplitude itself increases, the more the distance between the object and the ultrasonic sensor reduces. However, in contrast, the dominant factor here is that the elevation angle reduces as the distance decreases, as a result of which the amplitude of the reflected ultrasonic signal consequently decreases overall.

[0048] FIG. 3 shows a flow chart of a method 100 for characterizing an object in an environment of a motor vehicle. The motor vehicle includes an assistance system having a control device and a 1D ultrasonic sensor which is arranged on a front bumper of the motor vehicle, and which has a radiation pattern according to FIG. 1. The front of the motor vehicle approaches the object from a distance of approximately 2.5 meters and the ultrasonic sensor continually emits ultrasonic signals. The object is a curb which has a height which is approximately 40 cm less than the installation height of the ultrasonic sensor in the motor vehicle.

[0049] In a step 101, a first echo is received and a first amplitude of the first echo is ascertained.

[0050] In a subsequent step 102, a second echo which follows the first echo in time is received, and a second amplitude of the second echo is ascertained.

[0051] In a step 103, a first change in amplitude is determined on the basis of a comparison of the first amplitude with the second amplitude. In the present case, an amplitude increase is determined. Since the object is not yet located in the vicinity of the motor vehicle at the time of the measurement, that is to say is still at a distance of greater than two meters from the ultrasonic sensor of the motor vehicle, the elevation angle is approximately 90. Here, the power, more precisely the amplitude of the reflected ultrasonic signal, is consequently substantially dependent merely on the distance between the object and the ultrasonic sensor. That is to say that the amplitude of the reflected ultrasonic signal increases when the motor vehicle or the ultrasonic sensor approaches such an object, that is to say when the distance between the object and the ultrasonic sensor reduces. That is to say that the first change in amplitude here produces an amplitude increase over the course of time.

[0052] Since the object was not yet located in the vicinity of the motor vehicle at the time of the measurement, no final classification of the height of the object takes place yet based on the determined change in amplitude and the method 100 returns to step 102. A further, third echo which follows the second echo in time is thus received, and a third amplitude of the third echo is ascertained.

[0053] Subsequently, in step 103, a second change in amplitude is determined on the basis of a comparison of the second amplitude with the third amplitude. Since the motor vehicle continued moving in the direction of the object in the meantime and, at the time of the further measurement, the object is then located in the vicinity of the motor vehicle and, specifically, at a distance of 0.5 meters from the motor vehicle or ultrasonic sensor, an amplitude decrease is determined as the second change in amplitude. This is based on the fact that the elevation angle in this region is then substantially less than 90, which leads to the amplitude of the reflected ultrasonic signal decreasing overall, as a result of which the third amplitude of the third echo is smaller than the second amplitude of the second echo. That is to say that the second change in amplitude produces an amplitude decrease over the course of time here.

[0054] In a step 104, a classification of the height of the object is determined. To this end, a comparison of the first change in amplitude with the second change in amplitude takes place. Since, in the present case, an amplitude increase over the course of time is determined as the first change in amplitude and an amplitude decrease over the course of time is determined as the second change in amplitude, the object is classified as low.

[0055] Based on this method 100, the height of the object, in the present case the height of the curb, can be classified in an inexpensive and reliable manner.