METHOD AND DRIVER ASSISTANCE SYSTEM FOR CLASSIFYING OBJECTS IN THE SURROUNDINGS OF A VEHICLE

Abstract

A method for classifying objects in the surroundings of a vehicle using ultrasonic sensors which emit ultrasonic pulses and receive ultrasonic echoes reflected by objects. Distances between the sensors and objects reflecting ultrasonic pulses are ascertained via at least two ultrasonic sensors including overlapping fields of vision, and a position determination of the reflecting objects taking place using lateration and the assignment of the received ultrasonic echoes to object hypotheses for distinguishing between extensive objects and point-like objects. A height classification of a point-like object represented by an object hypothesis is carried out, based on an update rate of the object hypothesis, a stability of the position of the object represented by the object hypothesis, the amplitude of the ultrasonic echoes assigned to the object hypothesis, and a likelihood of the ultrasonic sensors receiving an ultrasonic echo from the object which is represented by the object hypothesis, as classification parameters.

Claims

1-10. (canceled)

11. A method for classifying objects in surroundings of a vehicle using ultrasonic sensors which emit ultrasonic pulses and receive back ultrasonic echoes reflected by objects, the method comprising: ascertaining, using at least two ultrasonic sensors having at least partially overlapping fields of vision, distances between each respective ultrasonic sensor of the at least two sensors and objects in the surroundings reflecting ultrasonic pulses; determining a position of the reflecting objects using lateration; assigning received ultrasonic echoes to object hypotheses for distinguishing between extensive objects and point-like objects; and carrying out a height classification of a point-like object represented by an object hypothesis of the object hypotheses, based on an update rate of the object hypothesis, a stability of the position of the object represented by the object hypothesis, an amplitude of the ultrasonic echoes assigned to the object hypothesis, and a likelihood of the at least two ultrasonic sensors receiving an ultrasonic echo from the object represented by the object hypothesis, as classification parameters.

12. The method as recited in claim 11, wherein the likelihood of each ultrasonic sensor receiving an ultrasonic echo for the object represented by the object hypothesis is determined based on the position of the object relative to the field of vision of the ultrasonic sensor, and/or an ascertained expansion of the object and/or a respective detection threshold of the ultrasonic sensor.

13. The method as recited in claim 12, wherein the respective detection threshold of each of the at least two ultrasonic sensors is adapted to an instantaneous noise level in such a way that a rate for an incorrect classification of an ultrasonic echo as the echo of an object is constant.

14. The method as recited in claim 11, wherein a correction of the amplitude of an ultrasonic echo takes place as a function of an ascertained expansion of the object represented by the object hypothesis.

15. The method as recited in claim 11, wherein a confidence value for the classification as a point-like object is taken into consideration as a further classification parameter for the height classification.

16. The method as recited in claim 11, wherein an update of each object hypothesis takes place when a further ultrasonic echo is added to the object hypothesis.

17. The method as recited in claim 11, wherein the height classification takes place using a statistical evaluation method or a machine learning method.

18. The method as recited in claim 17, wherein the height classification takes place using the machine learning method, a random forest method being used as the machine learning method.

19. A driver assistance system, comprising: at least two ultrasonic sensors having overlapping fields of vision; a control unit; wherein the driver assistance system is configured to classify objects in surroundings of a vehicle using the ultrasonic sensors, the ultrasonic sensors being configured to emit ultrasonic pulses and receive back ultrasonic echoes reflected by objects, the driver assistance system configured to: ascertain, using the at least two ultrasonic sensors, distances between each respective ultrasonic sensor of the sensors and objects in the surroundings reflecting ultrasonic pulses; determine a position of the reflecting objects using lateration; assign received ultrasonic echoes to object hypotheses for distinguishing between extensive objects and point-like objects; and carry out a height classification of a point-like object represented by an object hypothesis of the object hypotheses, based on an update rate of the object hypothesis, a stability of the position of the object represented by the object hypothesis, an amplitude of the ultrasonic echoes assigned to the object hypothesis, and a likelihood of the ultrasonic sensors receiving an ultrasonic echo from the object represented by the object hypothesis, as classification parameters.

20. The driver assistance system as recited in claim 19, wherein the driver assistance system includes a display function and a safety function, the display function representing information about the objects in the surroundings of the vehicle on a display device, and the safety function being configured to carry out an intervention in a driving function when a hazardous situation is present, wherein different weightings of the classification parameters are in each case provided for the display function and the safety function.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Exemplary embodiments of the present invention are described in greater detail based on the figures and the following description.

[0033] FIG. 1 shows a vehicle including a driver assistance system according to an example embodiment of the present invention in a view from the side.

[0034] FIG. 2 shows fields of vision of multiple ultrasonic sensors at the installation height of the sensors in a view from above.

[0035] FIG. 3 shows the fields of vision of the ultrasonic sensors at ground height in a view from above.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0036] In the following description of the specific example embodiments of the present invention, identical or similar elements are denoted by the same reference numerals, a repeated description of these elements in individual cases being dispensed with. The figures only schematically represent the subject matter of the present invention.

[0037] FIG. 1 shows a vehicle 1 which is situated on a street 22 in a view from the side. Vehicle 1 includes a driver assistance system 100 including an ultrasonic sensor 10 and a control unit 20. Only one ultrasonic sensor 10 is visible in the side view of FIG. 1; however, vehicle 1 includes multiple ultrasonic sensors 10; cf. FIGS. 2 and 3. In the specific embodiment shown in FIG. 1, driver assistance system 100 additionally includes a display device 28 connected to control unit 20. Control unit 20 is furthermore configured to carry out a brake intervention. This is shown in the representation of FIG. 1 by a connection of control unit 20 to a pedal 29.

[0038] Ultrasonic sensor 10 visible in FIG. 1 is mounted at vehicle 1 at an installation height h at the rear of vehicle 1. Ultrasonic sensor 10 has a field of vision 30 within which ultrasonic sensor 10 is able to recognize objects such as traffic sign 26 or a speed bump 24. The further speed bump 24′ also shown in FIG. 1, which compared to speed bump 24 is situated closer to vehicle 1, may no longer be recognized by ultrasonic sensor 10 in the situation shown in FIG. 1 since this further speed bump 24′ is situated outside field of vision 30 of ultrasonic sensor 10. A height classification of speed bump 24 may be recognized by a change in the amplitude or a change in the detection behavior when vehicle 1 approaches speed bump 24. If vehicle 1 backs up slowly in the direction of speed bump 24, the speed bump, at a certain point, will leave field of vision 30 of ultrasonic sensor 10, which becomes apparent from a drastic drop in an amplitude of a corresponding ultrasonic echo. The point in time or the distance of speed bump 24 from vehicle 1 at the point in time at which it is no longer recognizable by ultrasonic sensor 10 may then be used to draw conclusions on the height of speed bump 24. If speed bump 24 were a high object, similarly to traffic sign 26, it is not possible to leave field of vision 30 of ultrasonic sensor 10 when approached. It is only possible for field of vision 30 to be left during an approach in the case of low, generally traversable objects.

[0039] A reliable classification of traffic sign 26 as a high object, however, is not possible solely based on the amplitude due to the comparatively small area which is able to reflect ultrasound of ultrasonic sensor 10, and thus due to the comparatively small amplitudes of the received ultrasonic echoes. Additional criteria thus have to be used. According to the present invention, an update rate of an object hypothesis representing the object, the amplitude of the ultrasonic echo, the stability of the position determination of the object, and the likelihood of ultrasonic sensors 10 receiving an ultrasonic echo from the object, are used as classification parameters.

[0040] When a collision-relevant, i.e., a high, non-traversable object is recognized, a warning may be output via display device 28 and/or a brake intervention may take place.

[0041] FIG. 2 schematically shows the rear of vehicle 1 at which four ultrasonic sensors 10 are mounted in the example shown in FIG. 2. FIG. 2 schematically shows the fields of vision assigned to ultrasonic sensors 11 through 14 at installation height 31 through 34 of ultrasonic sensors 10; cf. FIG. 1.

[0042] FIG. 3 shows the same arrangement of ultrasonic sensors 10 of vehicle 1. In contrast to FIG. 2, the fields of vision are plotted at ground height 41 through 44.

[0043] It becomes apparent from comparison between FIGS. 2 and 3 that the fields of vision at installation height 31 through 34 are larger than the corresponding fields of vision at ground height 41 through 44 and that, in particular, areas in which fields of vision 31 through 34, 41 through 44 of at least two ultrasonic sensors 10 overlap are considerably larger, when viewed at installation height h, than at ground height.

[0044] It becomes apparent from the comparison of the fields of vision at installation height 31 through 34 of FIG. 2 to the fields of vision at ground height 41 through 44 that, in the case of an object which has a low height above the ground, there is a lower likelihood that it is simultaneously situated in field of vision 30 of at least two ultrasonic sensors 10 than for an object in the same position which has a height which at least corresponds to installation height h of ultrasonic sensors 10; cf. FIG. 1.

[0045] A lateration, and thus a position determination of an object reflecting an ultrasound, is only possible when at least two ultrasonic sensors 10 receive ultrasonic echoes reflected by this object. Object hypotheses which represent actual objects in the surroundings of vehicle 1 may only be created and/or updated when the position of the object reflecting the ultrasound is known. From this follows accordingly that, when measurements are continuously carried out using ultrasonic sensors 10, the likelihood that a high object is recognized is greater than a low object. Once an object has been recognized and, correspondingly, an object hypothesis has been created, it is correspondingly updated with a higher likelihood when it is a high object than when it is a low object. In this way, an update rate of an object hypothesis may be used as a criterion for carrying out a height classification.

[0046] Furthermore, it may be derived from the shown representation of the fields of vision at ground height 41 through 44 of FIG. 3 and the representation of the fields of vision at installation height 31 through 34 that the relative position of an object relative to fields of vision 31 through 34 and 41 through 44 also has an influence on the detection likelihood. Since the sound amplitude, proceeding from the center of fields of vision 31 through 34 and 41 through 44, steadily decreases toward the edges, the likelihood of being able to detect an object is greater when it is situated in the center of one or multiple field(s) of vision 31 through 34 and 41 through 44 than when the same object is situated at the edge of fields of vision 31 through 34 and 41 through 44. Accordingly, it is preferred to take the detection likelihood which is given by the relative position of the object at fields of vision 31 through 34 and 41 through 44 into consideration during the classification.

[0047] The present invention is not limited to the exemplary embodiments described here and the aspects highlighted therein. Rather, a plurality of modifications is possible within the scope of the present invention, which are within the capabilities of those skilled in the art in view of the disclosure herein.