ULTRASONIC SENSOR SYSTEM AND METHOD FOR DETECTING OBJECTS IN THE ENVIRONMENT OF A VEHICLE, AND VEHICLE HAVING AN ULTRASONIC SENSOR SYSTEM

Abstract

An ultrasonic sensor system for detecting objects in the environment of a vehicle is provided, which has a first group of ultrasonic sensors and a second group of ultrasonic sensors. The ultrasonic sensors of the first group each have a first installation height on the vehicle, the ultrasonic sensors of the second group of ultrasonic sensors each have a second installation height on the vehicle, the first installation height being greater than the second installation height. The ultrasonic sensors of the first group have a greater sensitivity for the detection of objects than the ultrasonic sensors of the second group.

Claims

1-15. (canceled)

16. An ultrasonic sensor system for detecting objects in an environment of a vehicle, comprising: a first group of ultrasonic sensors each having a first installation height on the vehicle; and a second group of ultrasonic sensors each having a second installation height on the vehicle, the first installation height being greater than the second installation height; wherein the ultrasonic sensors of the first group have a greater sensitivity for detection of objects than the ultrasonic sensors of the second group.

17. The ultrasonic sensor system as recited in claim 16, wherein respective directivities of the ultrasonic sensors of the first group have a positive vertical angle of inclination relative to a horizontal plane in a range of +0 to +15.

18. The ultrasonic sensor system as recited in claim 16, wherein respective directivities of the ultrasonic sensors of the second group are: (i) horizontally aligned, or (ii) have a negative vertical angle of inclination relative to a horizontal plane.

19. The ultrasonic sensor system as recited in claim 16, wherein respective directivities of the ultrasonic sensors of the first group have a smaller vertical opening angle than respective directivities of the ultrasonic sensors of the second group.

20. The ultrasonic sensor system as recited in claim 16, wherein the second group has at least as many ultrasonic sensors as the first group, a respective ultrasonic sensor of the second group being situated perpendicularly below each ultrasonic sensor of the first group.

21. The ultrasonic sensor system as recited in claim 16, wherein the second group has at least one ultrasonic sensor more than the first group, and a respective ultrasonic sensor of the first group being situated at an offset between two adjacent ultrasonic sensors of the second group, in each case.

22. The ultrasonic sensor system as recited in claim 16, wherein the ultrasonic sensors of the first group and the ultrasonic sensors of the second group have an identical design and different vertical angles of inclinations, the different vertical angles of inclination being due to a respective installation of the ultrasonic sensors of the first and second groups on a vehicle component.

23. The ultrasonic sensor system as recited in claim 22, wherein the vehicle component is a bumper.

24. The ultrasonic sensor system as recited in claim 16, wherein each of the ultrasonic sensors of the first and second groups include a diaphragm cup having a diaphragm able to oscillate and a wall surrounding the diaphragm, a piezoelectric transducer being disposed on an inner side of the diaphragm, the ultrasonic sensors of the first group having a smaller diaphragm diameter and/or a greater diaphragm stiffness than the ultrasonic sensors of the second group.

25. The ultrasonic sensor system as recited in claim 16, wherein each of the ultrasonic sensors of the first group and/or each of the ultrasonic sensors of the second group, has a funnel-shaped holder, a directivity of the ultrasonic sensors of the first group and/or a directivity of the ultrasonic sensors of the second group being influenced by the funnel-shaped holder.

26. The ultrasonic sensor system as recited in claim 16, wherein the ultrasonic sensors of the first group are operated at a higher transmission frequency than the ultrasonic sensors of the second group.

27. The ultrasonic sensor system as recited in claim 16, wherein the ultrasonic sensors of the first group are situated and aligned in such a way or have an angle of inclination such that objects above the vehicle are able to be detected using the ultrasonic sensors of the first group.

28. A vehicle, comprising: at least one ultrasonic sensor system for detecting objects in an environment of the vehicle, the at least one ultrasonic sensor system including: a first group of ultrasonic sensors each having a first installation height on the vehicle, and a second group of ultrasonic sensors each having a second installation height on the vehicle, the first installation height being greater than the second installation height, wherein the ultrasonic sensors of the first group have a greater sensitivity for detection of objects than the ultrasonic sensors of the second group; wherein the ultrasonic sensors of the first group and the second group are positioned on a front and/or a rear bumper of the vehicle.

29. The vehicle as recited in claim 28, wherein the first installation height has a value in a range of 50 cm to 80 cm, and the second installation height has a value in a range of 20 cm to 40 cm.

30. A method for detecting objects in an environment of a vehicle, the vehicle including at least one ultrasonic sensor system for detecting the objections, the at least one ultrasonic sensor system including a first group of ultrasonic sensors each having a first installation height on the vehicle, and a second group of ultrasonic sensors each having a second installation height on the vehicle, the first installation height being greater than the second installation height, wherein the ultrasonic sensors of the first group have a greater sensitivity for detection of objects than the ultrasonic sensors of the second group, wherein the ultrasonic sensors of the first group and the second group are positioned on a front and/or a rear bumper of the vehicle, the method comprising: detecting objects whose distance from the ultrasonic sensors of the first group is greater than a limit distance using the ultrasonic sensors of the first group; and detecting objects whose distance from the ultrasonic sensors of the second group is smaller than the limit distance using the ultrasonic sensors of the second group.

31. The method as recited in claim 30, wherein the limit distance is 40 cm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG. 1 shows a diagram of the installation heights in relation to the vertical angle of inclination of an ultrasonic sensor.

[0030] FIG. 2a) schematically illustrates a front view of a vehicle having an ultrasonic sensor system for detecting objects in the environment of the vehicle according to a first exemplary embodiment of the present invention.

[0031] FIG. 2b) schematically illustrates an ultrasonic sensor of the first group and an ultrasonic sensor of the second group of the ultrasonic sensor system, in accordance with an example embodiment of the present invention.

[0032] FIG. 3a) schematically illustrates a side view of a vehicle having an ultrasonic sensor system for detecting objects in the environment of the vehicle according to the related art.

[0033] FIG. 3b) schematically illustrates a side view of a vehicle having an ultrasonic sensor system for detecting objects in the environment of the vehicle according to a second exemplary embodiment of the present invention.

[0034] FIG. 4 schematically shows a front view a vehicle having an ultrasonic sensor system for detecting objects in the environment of the vehicle according to a third exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0035] In the description below of the exemplary embodiments of the present invention, identical elements are denoted by matching reference numerals and a repeated description of these elements is omitted as the case may be. The figures represent the object of the present invention merely schematically.

[0036] FIG. 1 shows a diagram 100 in which installation height h of an exemplary ultrasonic sensor of an ultrasonic sensor system for detecting objects in the environment of a vehicle has been plotted in cm on the x-axis versus the vertical angle of inclination of the ultrasonic sensor. The illustrated value ranges are defined by the design of the ultrasonic sensor and should therefore be understood merely as examples.

[0037] The range of combinations of installation height h and angle of inclination 110, which is restricted in the downward direction by curve 104, restricted for installation heights of more than approximately 46 cm in the upward direction by curve 106, and restricted for installation heights of less than 46 cm by curve 107, constitutes the range of combinations of h and that the ultrasonic sensors of typical ultrasonic sensor systems possess for detecting objects in the environment of a vehicle in order to satisfy both the requirements of the sensitivity and the requirement of still being able to detect low objects. Curve 105 represents the best compromise and was thus recommended in conventional ultrasonic sensor systems as what is known as an installation guideline. Curve 106 represents combinations of installation height and vertical angle of inclination at which echo signals from the ground are just barely still able to be detected (upper limit ground). Curve 104 represents combinations of installation height and angle of inclination at which the sensitivity is just barely still sufficient (low limit). Curve 107 represents combinations of installation height and angle of inclination at which barely any interfering echo signal will be received from a ceiling, e.g., of a garage or a parking facility (upper limit ceiling). Range 120 in systems according to the related art may possibly be tolerated if an application is involved in which the detection of low objects such as curbstones plays only a minor role. For example, low objects such as curbstones in the case of vehicles having a high chassis clearance (such as pickup trucks) are not very important. In smaller vehicles having a low chassis clearance and a small wheelbase (e.g., sports cars or city Flitzer cars), on the other hand, low objects are of a greater relevance. For instance, range 125 in systems according to the related art is permitted on the condition that the total range of the ultrasonic sensors is limited, such as to 150 cm, because there would otherwise be the risk that an interfering echo signal will be received from a ceiling such as in a garage or in a parking facility. Range 140 above curves 106 and 107 in systems according to the related art is not permitted, for instance because of the risk that an interfering echo from a ceiling, e.g., in a garage or in a parking facility, will be received and simultaneously no echo signals are received from the ground or from very low objects. For instance, range 130 below curve 104 is not allowed in systems according to the related art because the sensitivity is too low on account of the high portion of received ground echoes.

[0038] The present invention now makes it possible to place ultrasonic sensors even in the forbidden regions or to modify the form of the regions. For example, the ultrasonic sensors of the second group in an ultrasonic sensor system developed according to the present invention for the detection of objects in the environment of a vehicle may also be developed using combinations of installation height and vertical angle of inclination in range 130. The ultrasonic sensors of the first group of the ultrasonic sensor system developed according to the present invention may have combinations of installation height and vertical angle of inclination in ranges 110, 120 and 125, and these ranges may be enlarged, for instance in that the ultrasonic sensors of the first group have a smaller opening angle in their directivity.

[0039] FIG. 2a) schematically shows a front view of a vehicle 10 having an ultrasonic sensor system 20 for detecting objects in the environment of vehicle 10 according to a first exemplary embodiment of the present invention. Ultrasonic sensor system 20 includes twelve ultrasonic sensors 12, 14, of which six ultrasonic sensors 12 belong to a first group 22 of ultrasonic sensors, and six ultrasonic sensors 14 belong to a second group 24. Ultrasonic sensors 12 of first group 22 have a first installation height h.sub.1 on the vehicle relative to a road surface 40. Ultrasonic sensors 14 of second group 24 have a second installation height h.sub.2 on the vehicle relative to road surface 40, first installation height h.sub.1 being greater than second installation height h.sub.2. According to the present invention, ultrasonic sensors 12 of first group 22 have a greater sensitivity for the detection of objects than ultrasonic sensors 14 of second group 24.

[0040] In this example, the number of ultrasonic sensors 12 of first group 22 corresponds to the number of ultrasonic sensors 14 of second group 24. Situated perpendicularly above each ultrasonic sensor 14 of second group 24 is an ultrasonic sensor 12 of first group 22. This placement makes it possible to infer the height of an acquired echo signal in relation to road surface 40 via a simple trilateration in the vertical, and thus to infer the height of a detected object.

[0041] FIG. 2b) schematically shows an ultrasonic sensor 12 of first group 22 and an ultrasonic sensor 14 of second group 24 of ultrasonic sensor system 20 from FIG. 2a). In this particular example, ultrasonic sensor 12 has a positive vertical angle of inclination . Directivity 52 or main axis 50 of the directivity is upwardly inclined relative to horizontal 45. Ultrasonic sensor 14 has a directivity 54 that is not inclined relative to horizontal 45. Opening angle .sub.1 of directivity 52 of ultrasonic sensor 12 is smaller than opening angle .sub.2 of directivity 54 of ultrasonic sensor 14.

[0042] FIG. 3a) schematically shows a side view of a vehicle 10 having a conventional ultrasonic sensor system for detecting an object 80 according to the related art. The ultrasonic sensor system has at least one ultrasonic sensor 16, which is installed at a certain installation height h.sub.s relative to road surface 40. Installation height h.sub.s amounts to 50 cm, for example. Shown is directivity 56 or the vertical field of view of ultrasonic sensor 16. It has an opening angle .sub.s and furthermore has no inclination of the main axis relative to horizontal 45 in this particular example. It can be seen that the field of view intersects with road surface 40 at a distance d.sub.0. Low objects that are located closer to this limit distance d.sub.0 from the vehicle, i.e., roughly in gap region 58, may possibly not be detected at all by ultrasonic sensor 16 or only in a very unreliable fashion. This may lead to a risk to the vehicle or also to the object.

[0043] FIG. 3b) schematically shows a side view of vehicle 10 having an ultrasonic sensor system 20 for detecting an object 80 according to a second exemplary embodiment of the present invention. Ultrasonic sensor system 20 has two groups 22, 24 of ultrasonic sensors 12, 14, each being mounted at a certain first and second installation height h.sub.1 and h.sub.2, respectively, relative to road surface 40. Installation height h.sub.1 amounts to 50 cm, for example. Shown is directivity 52 or the vertical field of view of an ultrasonic sensor 12 of first group 22 having installation height h.sub.1. In this example it has no inclination of the main axis with respect to horizontal 45, but opening angle .sub.1 of directivity 52 is smaller in comparison with opening angle .sub.s according to the related art of FIG. 2a). This has the result that the field of view intersects with road surface 40 at a distance d.sub.1, d.sub.1 being greater than d.sub.0. This has the effect that fewer ground echoes are received by ultrasonic sensor 12, or that ground echoes having a lower intensity are received so that the detection threshold of ultrasonic sensor 12 is able to be selected to have a corresponding greater sensitivity. Ultrasonic sensor 12 thus has a greater sensitivity, in particular for high objects, than ultrasonic sensor 16 of the related art. However, low objects 80 that are located closer to vehicle 10 than limit distance d.sub.1 are not detected by ultrasonic sensor 12 or only very unreliably. According to the present invention, this detection gap is closed by utilizing second group 24 of ultrasonic sensors 14. Ultrasonic sensor 14 has a field of view or a directivity 54 that essentially covers the region of close and low objects 81 and consequently allows for a reliable detection of such objects 81.

[0044] FIG. 4 schematically shows a front view of a vehicle 10 including an ultrasonic sensor system 20 for detecting objects in the environment of sensor 10 according to a third exemplary embodiment of the present invention. In this case, ultrasonic sensor system 20 includes eleven ultrasonic sensors 12, 14, of which five ultrasonic sensors 12 belong to a first group 22 of ultrasonic sensors and six ultrasonic sensors 14 belong to a second group 24. Ultrasonic sensors 12 of first group 22 have a first installation height h.sub.1 on the vehicle relative to a road surface 40. Ultrasonic sensors 14 of second group 24 have a second installation height h.sub.2 on the vehicle relative to road surface 40, first installation height h.sub.1 being greater than second installation height h.sub.2. According to the present invention, ultrasonic sensors 12 of first group 22 have a greater sensitivity for the detection of objects than ultrasonic sensors 14 of second group 24.

[0045] In this example, the number of ultrasonic sensors 14 of second group 24 corresponds to the number of ultrasonic sensors 12 of first group 22 plus one. An ultrasonic sensor 12 of first group 22 is situated at an offset between two adjacent ultrasonic sensors 14 of second group 24. Because of such a placement of ultrasonic sensors 12 in the upper row (second group 22) between ultrasonic sensors 14 in the lower row (first group 24), the region of the bumper of the vehicle in the horizontal is advantageously able to be covered in a more optimal manner because horizontal distance x between two adjacent ultrasonic sensors 12, 14 is reduced, e.g., in comparison with a placement according to FIG. 2a). For example, in locations 15, where a large distance is required between adjacent ultrasonic sensors of second group 24 (e.g., at the number plate holder), horizontal distance x between a sensor 12 of the first group and next sensor 14 of the second group is able to be reduced. This results in a sufficient sensor coverage to ensure the reliable detection of low objects also in region 15 of the number plate.