Method for determining the position of an object by means of an ultrasonic parking sensor

Abstract

The invention relates to a method for determining the position of an object by means of an ultrasonic parking sensor, having the steps of generating a modulated excitation signal with a first frequency and a second frequency for the ultrasonic parking sensor; exciting the ultrasonic parking sensor using the excitation signal in order to generate an ultrasonic signal with the first frequency with a first field of view and a second frequency with a second field of view, the first field of view differing from the second field of view; receiving, by means of the ultrasonic parking sensor, the ultrasonic signal reflected on the object; and evaluating the received amplitudes of the first frequency and the second frequency of the reflected ultrasonic signal in order to determine the position of the object.

Description

[0001] Description

[0002] title

[0003] Method for determining the position of an object using an ultrasonic parking sensor

[0004] State of the art

[0005] The present invention relates to a method for determining the position of an object by means of an ultrasonic parking sensor and the associated ultrasonic parking sensor with exactly one ultrasonic transducer.

[0006] The measuring principle of ultrasonic parking sensors is based on acoustic waves. These are emitted in the inaudible range and reflected by an obstacle. The reflected signal is received by the ultrasonic parking sensor, where electronics evaluate the signal using a time measurement. Ultrasonic parking sensors have a field of view that defines the distances and angles at which an object is detected. Currently, this field of view is a fixed component of the ultrasonic parking sensor's design and cannot be dynamically adjusted within the field. The field of view depends, among other things, on the diaphragm geometry and the resonant frequency of the ultrasonic parking sensor. According to the current state of research, dynamic adjustment of the field of view is only possible using phased arrays. These consist of multiple ultrasonic transducers and, via electronic control, allow the sound beam to be swiveled.Due to the complexity of such systems, no implementations are currently available on the market. A cost-effective ultrasonic parking sensor with a variable field of view, enabling the determination of an object's position within that field, would be desirable. Disclosure of the invention.

[0007] The method according to the invention, comprising the features of claim 1, and the ultrasonic parking sensor according to the invention, comprising the features of claim 9, have the advantage that the position of the ultrasonic parking sensor relative to an object in the field of view can be determined using a simple and cost-effective ultrasonic parking sensor. This is achieved according to the invention by the method for determining the position of an object using an ultrasonic parking sensor, in a first step, generating a modulated excitation signal with a first frequency and a second frequency for the ultrasonic parking sensor. Subsequently, the ultrasonic parking sensor is excited by the excitation signal in order to simultaneously emit an ultrasonic signal with the first frequency to a first field of view and a second frequency to a second field of view, wherein the first field of view differs from the second field of view.After the emitted ultrasound signal is reflected by the object, the reflected ultrasound signal is received by the ultrasonic parking sensor. The received amplitudes of the first and second frequencies of the reflected ultrasound signal are then evaluated to determine the object's position. Thus, by controlling the ultrasonic parking sensor with two different frequencies that propagate through two different fields of view, the position of an object within the field of view can be determined by evaluating the reflected ultrasound signal. Position determination includes, in particular, determining the distance between the object and the ultrasonic parking sensor, as well as determining the solid angle to the object and / or assigning the object to a defined area in front of the ultrasonic parking sensor.An ultrasonic signal reflected by an object outside the sensor's field of view cannot be detected by the ultrasonic parking sensor. This object could be, for example, another road user or a pedestrian. The amplitudes of the first and second frequencies from the received ultrasonic signal are preferably determined using a Fast Fourier Transform.

[0008] The dependent claims describe preferred embodiments of the invention.

[0009] Preferably, an object's position at the edge of the ultrasonic parking sensor is detected when the received ultrasonic signal has only one frequency or one second frequency. The ultrasonic signal received from an edge position originates, in particular, from the frequency with the wider field of view. This allows for a quick and easy determination of the object's approximate position relative to the ultrasonic parking sensor.

[0010] Preferably, no object is detected in the first or second field of view if no reflected ultrasound signal is received. In particular, no reflected ultrasound signal is received if the signal strength of the reflected ultrasound signal is less than the background noise. Thus, the presence of an object in the first or second field of view can be reliably ruled out.

[0011] The first field of view is preferably more tightly focused than the second field of view. A central position of the object relative to the ultrasonic parking sensor is detected when the amplitude of the first frequency is greater than the amplitude of the second frequency in the received ultrasonic signal. Due to the tighter focus of the first field of view, the signal strength of the first frequency is greater than that of the second frequency for central positions relative to the ultrasonic parking sensor. When the ultrasonic signal is reflected by an object in a central position, the amplitude of the first frequency is also greater than the amplitude of the second frequency. Thus, an object in a central position in front of the ultrasonic parking sensor can be reliably identified.

[0012] A lateral position of the object is preferentially detected when the amplitude of the second frequency is greater than the amplitude of the first frequencies in the received ultrasonic signal. Due to the lower focus of the second frequency with the second field of view, this field exhibits a higher signal strength at its edges than the more focused first field of view. The lateral position lies between the edge position and the center position. Thus, objects can be easily and reliably assigned to an area oriented laterally to the ultrasonic parking sensor.

[0013] The excitation signal is preferably amplitude-modulated or frequency-modulated. Modulation allows the ultrasonic parking sensor to be reliably excited with two frequencies in order to emit these frequencies simultaneously. Preferably, a ratio of the received amplitudes is evaluated to determine the object's position. By evaluating this ratio, a continuous characteristic can be assigned to the object's position. Thus, evaluating the ratio improves the object's position determination using the ultrasonic parking sensor.

[0014] Preferably, the quotient is assigned an angle of the reflecting object to a central axis of the ultrasonic parking sensor. The central axis preferably corresponds to the main outward transmission direction of the ultrasonic signal. For example, if the amplitude of the first frequency is in the numerator and the amplitude of the second frequency is in the denominator, and the first frequency has a more focused first field of view than the second frequency, then a high quotient indicates a small angle of the reflected object to the central axis, and a small quotient indicates a large angle of the reflecting object to the central axis.

[0015] If there are two or more possible solutions for the position of the object, for example for a left-hand angle and a right-hand angle from the central axis, sensor information from another sensor is preferably used, in particular a reflected ultrasonic signal of the object received by another ultrasonic parking sensor.

[0016] Furthermore, the invention relates to an ultrasonic parking sensor with exactly one ultrasonic transducer, wherein the ultrasonic parking sensor is configured to perform the previously described method in order to determine the position of an object within the field of view of the ultrasonic parking sensor. Thus, the position of the object relative to the ultrasonic parking sensor can be determined quickly and reliably using a simple ultrasonic parking sensor.

[0017] Brief description of the drawings

[0018] A preferred embodiment of the invention is described in detail below with reference to the accompanying drawings. Figure 1 shows a flowchart of the method for determining the position of an object using an ultrasonic parking sensor according to the preferred embodiment of the invention.

[0019] Figure 2 shows a schematic representation of the ultrasonic parking sensor with first field of view and second field of view.

[0020] Figure 3 shows a frequency diagram of a received ultrasound signal.

[0021] Figure 4 shows the ultrasonic parking sensor with different areas for classifying the object's position, and

[0022] Figure 5 shows a line diagram with the ratio of the quotient of the received amplitudes to the angle of the reflecting object to a central axis.

[0023] Embodiments of the invention

[0024] Preferably, all identical components, elements and / or units in all figures are provided with the same reference numerals.

[0025] The following describes, with reference to Figures 1 to 5, a method for determining the position of an object 2 using an ultrasonic parking sensor 1 and the ultrasonic parking sensor 1.

[0026] Figure 1 schematically shows the process steps of the method for determining the position of an object 2 using an ultrasonic parking sensor 1. In a first step S1, a modulated excitation signal with a first frequency 10 and a second frequency 20 is generated for the ultrasonic parking sensor 1. The excitation signal is generated, in particular, by means of amplitude modulation or frequency modulation.

[0027] In step S2, the ultrasonic parking sensor 1 is then excited with the excitation signal to simultaneously emit an ultrasonic signal with the first frequency 10 and the second frequency 20. The first frequency 10 corresponds to a first field of view 11, and the second frequency 20 to a second field of view 21, which differs from the first field of view 11. For example, lower frequencies generate wider fields of view than higher frequencies. If an object 2, such as another vehicle, is located in the first field of view 11 or the second field of view 21, the ultrasonic signal is reflected.

[0028] The reflected ultrasonic signal 3 is received in step S3 by means of the ultrasonic parking sensor 1 and subsequently evaluated in step S4. The received amplitudes 4 of the first frequency 10 and the second frequency 20 are evaluated to determine the position of the object 2.

[0029] The distance to object 2 is preferably determined by means of a time-of-flight analysis of the ultrasonic signal. Furthermore, the direction of the reflecting object 2 towards the ultrasonic parking sensor 1 can be determined by comparing the received amplitudes 4 of the first frequency 10 and the second frequency 20. The amplitudes 4 of the first frequency 10 and the second frequency 20 are preferably determined by means of a Fast Fourier Transform.

[0030] Figure 2 shows the ultrasonic parking sensor 1 with its first field of view 11 and second field of view 21. The first frequency 10 is higher than the second frequency 20, so the first field of view 11, corresponding to the first frequency 10, is more focused than the second field of view 21, corresponding to the second frequency 20. The first field of view 11 has a greater range along a central axis XX than the second field of view 21. Due to the different focus, the first field of view 11 and the second field of view 21 exhibit different sensitivities across the angle α. For example, the more focused first field of view 11 generates a greater amplitude than the second field of view 21 when the object 2 is in a central position 31 in front of the ultrasonic parking sensor 1.

[0031] Figure 3 shows a frequency diagram of the received ultrasound signal 3. The received ultrasound signal 3 was decomposed into its frequencies f using a Fast Fourier Transform. The measured amplitude 4 for each frequency f is shown. The amplitude 4 is plotted on the ordinate, while the corresponding frequency f is plotted on the abscissa. The diagram exhibits two amplitude peaks, which correspond to the first frequency 10 and the second frequency 20. The amplitude 4 of the first frequency 10 is slightly larger than the amplitude 4 of the second frequency 20. Thus, it can be seen that the object 2, from which the ultrasound signal was reflected, is located in a central position 31 relative to the ultrasound parking sensor 1.

[0032] Figure 4 shows the ultrasonic parking sensor 1 with different zones into which the object 2 can be easily classified by comparing the received amplitudes 4.

[0033] The object 2 is classified in a central position 31 if the amplitude 4 of the first frequency 10 is greater than the amplitude 4 of the second frequency 20 in the received ultrasonic signal 3. This depends in particular on the fact that the first field of view 11 is more focused than the second field of view 21, so that the signal strength of the emitted ultrasonic signal in the central position 31 in front of the ultrasonic parking sensor 1 is greater than that of the second field of view 21.

[0034] If the first field of view 1 has a greater range than the second field of view 21, an object 2 in a central position 31 can only be detected by the first field of view 11, so that the ultrasonic parking sensor 1 only detects the amplitude 4 of the first frequency 10.

[0035] An edge position 30 of object 2 relative to the ultrasonic parking sensor 1 is detected when the received ultrasonic signal 3 has only a second frequency 20. Edge position 30 is located outside the first field of view 11. Due to the wider solid angle of the second field of view 21, object 2 at edge position 30 can only reflect the ultrasonic signal of the second field of view 21, thus allowing object 2 to be easily assigned to a defined area.

[0036] At the edges of the first field of view 11, the intensity of the first field of view 11 decreases, with a lateral position 33 existing in a region between the edge position 30 and the central position 31, in which the amplitude of the second frequency 20 is greater than the amplitude 4 of the first frequency 20 in the received ultrasonic signal 3. Figure 5 shows a quotient 5 of the received amplitudes 4 at a corresponding angle α of the reflecting object 2 to the central axis XX of the ultrasonic parking sensor 1. The quotient 5 is formed from the amplitude 4 of the first frequency 10 in the denominator and the amplitude 4 of the second frequency 20 in the numerator. For angles α up to approximately 20°, the quotient 5 is less than one, so that the amplitude 4 of the first frequency 10 is greater than the amplitude 4 of the second frequency 20 in the received ultrasonic signal 3.

[0037] At an angle α of 30°, the quotient 5 is slightly more than one, at an angle α of 40° it is approximately 1.5, and at an angle α of 50° it is approximately two. At even larger angles α, the quotient 5 increases sharply, so that at an angle α of 60° it is approximately three, and at an angle α of 70° it is almost six. Angles α greater than 70° lie outside the first field of view 11 and the second field of view 21 and cannot be detected by the ultrasonic parking sensor 1. Thus, the quotient 5 allows for a continuous assignment of the object's position 2 to the central axis XX using the angle α.

Claims

Claims 1. Method for determining the position of an object (2) using an ultrasonic parking sensor (1), comprising the steps: - Generating (S1) a modulated excitation signal with a first frequency (10) and a second frequency (20) for the ultrasonic parking sensor, - Excitation (S2) of the ultrasonic parking sensor (1) with the excitation signal to simultaneously emit an ultrasonic signal with the first frequency (10) with a first field of view (11) and a second frequency (20) with a second field of view (21), wherein the first field of view (11) differs from the second field of view (21), - Receiving (S3) the ultrasonic signal (3) reflected from the object (2) by means of the ultrasonic parking sensor (1) and - Evaluating (S4) the received amplitudes (4) of the first frequency (10) and the second frequency (20) of the reflected ultrasound signal (3) to determine a position of the object (2).

2. Method according to claim 1, wherein an edge position (30) of the object (2) is detected relative to the ultrasonic parking sensor (1) when the received ultrasonic signal (3) has only a first frequency (10) or a second frequency (20).

3. Method according to one of the preceding claims, wherein no object (2) is determined in the first field of view (11) and second field of view (21) when no reflected ultrasound signal (3) is received.

4. Method according to claim 1, wherein the first field of view (11) is more focused than the second field of view (21) and wherein a central position (31) of the object (2) to the ultrasonic parking sensor (1) is detected when the amplitude (4) of the first frequency (10) is greater than the amplitude (4) of the second frequency (20) in the received ultrasonic signal (3).

5. Method according to claim 4, wherein a lateral position (32) of the object (2) is detected when the amplitude (4) of the second frequency (20) is greater than the amplitude (4) of the first frequency (20) in the received ultrasound signal (3).

6. Method according to one of the preceding claims, wherein the generated excitation signal is amplitude-modulated or frequency-modulated.

7. Method according to one of the preceding claims, wherein a quotient (5) of the received amplitudes (4) is evaluated to determine a position of the object.

8. Method according to claim 7, wherein the quotient (5) is associated with an angle (a) of the reflecting object (2) to a central axis (XX) of the ultrasonic parking sensor (1).

9. Ultrasonic parking sensor with exactly one ultrasonic transducer, wherein the ultrasonic parking sensor (1) is configured to perform a method according to one of the preceding claims to determine a position of an object (2) in a field of view of the ultrasonic parking sensor (1).

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