Method for transmitting multiple ultrasonic bursts with a distance-dependent ultrasonic burst spacing

Abstract

Method for transmitting an ultrasonic burst for use in ultrasonic sensor systems in vehicles, comprising the steps - Step 1: Emission of an ultrasonic burst with an ultrasonic burst duration (bd) not exceeding a maximum ultrasonic burst duration (bd) by an ultrasonic sensor system (USS); - Step 2: Receiving an ultrasonic burst reflected by an object (O); - Step 3: Determining the distance (D) between the ultrasonic sensor system (USS) and the object (O) as a function of the received reflected ultrasonic burst; - Step 4: Repeating steps 1 to 4, wherein the ultrasonic burst duration (bd) depends on the determined distance (D, s1, s2), characterized in that - that at least several ultrasonic bursts (UB) are emitted at a temporal ultrasonic burst interval and - that the first temporal ultrasonic burst interval is the time interval between the ultrasonic burst start (UBS) of a first ultrasonic burst and the ultrasonic burst start (UBS) of the second ultrasonic burst immediately following this first ultrasonic burst and - that the second temporal ultrasonic burst interval between the ultrasonic burst start (UBS) of the second ultrasonic burst and the ultrasonic burst start (UBS) of the third ultrasonic burst immediately following this second ultrasonic burst depends on the determined distance (D) and - wherein the ultrasonic burst length of the ultrasonic burst duration (bd) is increased by the fourth root of the determined distance (D).

Description

Field of invention

[0001] The invention relates to a method for emitting an ultrasonic burst for use in ultrasonic sensor systems in vehicles. General introduction

[0002] Autonomous driving requires increasingly sophisticated measurement devices to monitor the vehicle's surroundings. The bandwidth of the ultrasonic signals that can be transmitted and received is significantly limited, as the ultrasonic transducers used exhibit a strong resonance with high Q and thus a narrow bandwidth.

[0003] An optimization of the modulation frequency curve within a chirp signal is therefore necessary.

[0004] In this context, we refer to WO 2010 / 063510 A1. WO 2010 / 063510 A1 describes a detection device and a method for detecting the surroundings of a vehicle. WO 2010 / 063510 A1 uses such signals, which are particularly relevant in connection with the use of ultrasound in vehicles.

[0005] EP 1 231 481A2 discloses a method for operating an ultrasonic multi-sensor array which does not address the bandwidth problem.

[0006] An ultrasonic sensor with a separate ultrasonic transmitter and ultrasonic receiver is known from US 7 693 007 B2.

[0007] WO 2010 / 063 510 A1 discloses a detection device, particularly for detecting the surroundings of a vehicle. WO 2010 / 063 510 A1 does not address the bandwidth issue.

[0008] DE 10 2008 002 232 A1 discloses a method and device for determining the distance and / or speed of an object relative to a vehicle. DE 10 2008 002 232 A1 does not address the bandwidth issue.

[0009] DE 101 45 292 A1 discloses a method for measuring distance using ultrasound. DE 101 45 292 A1 does not address the bandwidth issue.

[0010] JP S58-50 484 A discloses a guidance device for reversing a motor vehicle using ultrasound. JP S58-50 484 A does not address the bandwidth issue.

[0011] None of the presented fonts solves the bandwidth problem or contributes to such a solution. Task

[0012] The proposal is therefore based on the task of creating a solution which does not have the above-mentioned disadvantages of the prior art and has further advantages.

[0013] This problem is solved by a proposal according to the claims. More precisely, its solution is supported by the proposal according to the claims. Further refinements are the subject of the dependent claims. Solution to the task

[0014] The invention relates to a method for transmitting an ultrasonic burst for use in ultrasonic sensor systems in vehicles. The method comprises the following steps: 1. Step 1: Emission of an ultrasonic burst with an ultrasonic burst duration (bd) not exceeding a maximum ultrasonic burst duration (bd) by an ultrasonic sensor system (USS); 2. Step 2: Receiving an ultrasonic burst reflected by an object (O); 3. Step 3: Determining the distance (D) between the ultrasonic sensor system (USS) and the object (O) depending on the received reflected ultrasonic burst; 4. Step 4: Repeat steps 1 to 4, whereby the ultrasonic burst duration (bd) depends on the determined distance (D, s1, s2).

[0015] The method is characterized in that a plurality of ultrasonic bursts (UB) are emitted at a temporal ultrasonic burst interval. The first temporal ultrasonic burst interval is the temporal interval between the ultrasonic burst start (UBS) of a first ultrasonic burst and the ultrasonic burst start (UBS) of the second ultrasonic burst immediately following this first ultrasonic burst. The second temporal ultrasonic burst interval between the ultrasonic burst start (UBS) of the second ultrasonic burst and the ultrasonic burst start (UBS) of the third ultrasonic burst immediately following this second ultrasonic burst depends on the determined interval (D).

[0016] One method for adapting ultrasonic signals, or more precisely ultrasonic bursts (UB), to the object under investigation in the vehicle's environment is to adapt the transmission amplitude and transmission frequency upon detection of an object depending on object properties such as distance and / or reflectivity. For this purpose, the reception amplitude is measured by an ultrasonic measuring device, the ultrasonic sensor system (USS), using appropriate ultrasonic receivers and / or ultrasonic transducers (US1, US2, US3) and compared with a target reception amplitude curve. If the reception amplitude is too high at any given time, the ultrasonic transducers are attenuated individually or jointly. The attenuation of one or more ultrasonic transducers is preferably achieved by connecting attenuation elements, for example, by connecting resistors in parallel to the ultrasonic transducers (US1, US2, US3).If the amplitude is too low, the ultrasound transducer in question is supplied with more vibration energy.

[0017] Another method is the control of the ultrasonic burst amplitude (A) at which the ultrasonic transducer (US1, US2, IS3) transmits. This method attempts to keep the received amplitude of the echoes constant when received by the ultrasonic transducer (US1, US2, US3) at the location of the respective ultrasonic transducer or at the location of the ultrasonic sensor system (USS), which comprises multiple ultrasonic transducers (USS). A central idea of ​​this disclosure is the adaptation of ultrasonic burst properties to the previously detected environment. Ultimately, it is irrelevant whether the detection was carried out using ultrasound or other methods such as radar and / or lidar and / or by image analysis of camera images.Such an adaptation of an ultrasonic burst characteristic for emitted ultrasonic bursts can, for example, be an increase and / or decrease in the ultrasonic burst amplitude during the emission of the ultrasonic burst depending on the distance of an object to be examined or detected. Similarly, the instantaneous frequency of the ultrasonic burst can also be increased or decreased during the emission of the ultrasonic burst depending on the distance of the object.

[0018] Particularly preferred is a substantially hyperbolic curve of the ultrasonic burst instantaneous frequency as a function of time within an ultrasonic burst for better Doppler robustness.

[0019] For the detection of a small object, such as the size of a moth, a sound pressure of 130 dB with a 10 ms ultrasonic burst duration and a 110 ms time interval between two consecutive ultrasonic bursts is typically appropriate at a distance of 15 m. High sound pressure, low frequency, long pulse duration, and low pulse repetition rate are important.

[0020] When approaching an object in the vehicle environment that has been identified as important, the tasks • exact 3D localization • Structure detection (object classification, size, sensitive object components (e.g. certain body parts of a person to be protected)) • Compensation of the Doppler effect

[0021] Ultrasound bursts in this phase: • Short with high repetition rate (80 to 90 ultrasonic bursts / second when approaching), • up to 200 ultrasonic bursts per second near the object, • Broadband transmission and reception of ultrasonic bursts to obtain more spectral information, • Linear or hyperbolic downward frequency modulation of the ultrasonic bursts, • Reduction of the ultrasonic burst amplitude near the object, which prevents overloading.

[0022] During the approach phase to the object or a group of objects, the ultrasonic bursts are preferably continuously modified in their sequence and shape during the approach: At greater distances, the ultrasonic bursts are preferably loud, with a large ultrasonic burst amplitude and a relatively low-frequency instantaneous ultrasonic frequency, and preferably narrowband. Frequency-modulated so-called chirps with a higher starting frequency and a quieter, i.e., smaller, ultrasonic burst amplitude are preferably used near the object or objects. For good processing, very fast signal processing for high pulse repetition frequencies is advisable.

[0023] A 3D localization option for objects can be achieved using several ultrasound transducers that are appropriately positioned relative to one another. If the ultrasound transducers are very broadband, two sensors can be placed next to each other at "ear's distance," for example. This document proposes increasing the broadband capability by coupling several ultrasound transducers to form an ultrasound sensor system. Direction can be determined, in particular, using time-of-flight differences. The evaluation of such time-of-flight differences can be performed using a neural network. The relationship between the height of the reflecting object and the frequency content of the echo can also be evaluated using a neural network. One proposal, which will be further developed below, involves two ultrasound transducers placed close to one another.One of these two ultrasonic transducers should be equipped with a low resonance frequency and the other of the two ultrasonic transducers should be equipped with a high resonance frequency, which are activated at different distances from the object to emit the ultrasonic bursts.

[0024] A vehicle moving towards an object must compensate for two Doppler errors: a. Distance error: overestimation of the distance to the object, b. Accuracy error: The object can no longer be located as precisely (widening of the CCF curve)

[0025] Compensation is necessary for this: 1. Both errors are reduced if the bandwidth is increased while maintaining the same ultrasonic burst duration, or if the ultrasonic burst duration is reduced while maintaining the same bandwidth. 2. Since the vehicle is typically moving toward the object of interest, this leads to an underestimation of the distance based on time-of-flight determinations. This can compensate for the overestimation due to the Doppler effect at a certain distance from the object. Therefore, the proposed method continuously adjusts the ultrasonic burst so that the compensated distance corresponds to the actual distance. A neural network is preferably used for this purpose. This neural network preferably controls one or more ultrasonic burst parameters of one or more subsequent ultrasonic bursts based on one or more received ultrasonic signals or on signals derived from the received ultrasonic signals. 3. A complete compensation of the accuracy error occurs only with a strictly hyperbolic frequency modulation of the ultrasonic burst instantaneous frequency during the ultrasonic burst as a function of time (t).

[0026] In principle, a short ultrasonic burst duration with a high bandwidth is desirable to obtain maximum information. By training a neural network to adapt the ultrasonic burst characteristics of future ultrasonic bursts, this neural network can be used to determine and adjust these ultrasonic burst characteristics before an ultrasonic burst is transmitted. The goal is optimal ultrasonic burst adaptation for variable compensating distances.

[0027] For structural detection and / or object classification, it is useful to evaluate the fine structure of the echoes from ultrasonic bursts. This takes advantage of the fact that each part of an object, such as a pedestrian, reflects the ultrasonic burst at slightly different times. The resulting temporal fine structure of the echo can then be used to create a "depth profile" of the object. At the same time, spectral differences also arise due to the different reflection / absorption behavior of different materials on the object's various surfaces.

[0028] As with 3D localization, differences between the received signals from multiple ultrasonic sensor systems with multiple ultrasonic transducers are evaluated. The environment of the ultrasonic sensor system, such as the type of mounting or the structure of the surfaces surrounding the ultrasonic sensor system, and other components, typically add further frequency filtering, the range of which the neural network used for evaluation must be trained to.

[0029] Another method relates to a process for transmitting an ultrasonic signal using an ultrasonic sensor system (USS). The ultrasonic signal comprises an ultrasonic burst (UB), wherein the ultrasonic burst comprises at least two, but typically considerably more, ultrasonic pulses (P0 to P7). Each of the at least two ultrasonic pulses (P0 to P7) has a temporal ultrasonic pulse start and a temporal ultrasonic pulse end. For example, the intersection point of the burst-like fluctuating sound pressure during the ultrasonic burst with the 50% sound pressure amplitude relative to the maximum sound pressure occurring during an ultrasonic pulse can be used to determine the ultrasonic pulse start and end.For the purposes of this document, the ultrasonic period (T1 to T7) of a single ultrasonic pulse (P0 to P7) is the time from the temporal ultrasonic pulse end of the immediately preceding ultrasonic pulse to the temporal ultrasonic pulse end of the respective ultrasonic pulse. These definitions are chosen to determine an instantaneous ultrasonic frequency (f). m ) in the time of the ultrasonic pulse. In the broadest sense, an ultrasonic pulse as defined in this document is a wavelet whose stretching factor can be varied during the duration of the ultrasonic pulse. Therefore, any type of time-limited wavelet with a time-limited wavelet duration is encompassed by the term ultrasonic pulse in this document. The wavelet duration corresponds to the ultrasonic pulse duration (dh) of the ultrasonic period (T1 to T7). The respective instantaneous ultrasonic frequency (f m1 to f m7) is the inverse of the respective ultrasonic period (T1 to T7) of the respective ultrasonic pulse (P0 to P7). The rate of change (v f ) of the instantaneous ultrasonic frequency (f m ) is thus the first derivative of the instantaneous ultrasonic frequency (f m ) after the time (t). The ultrasonic burst (UB) begins at an ultrasonic burst start (UBS), which is equal to the ultrasonic pulse start of the first pulse (P0) of the ultrasonic burst (UB). The ultrasonic burst (UB) ends at an ultrasonic burst end (UBE), which is equal to the ultrasonic pulse end of the last pulse (P7) of the ultrasonic burst (UB). The ultrasonic burst (UB) has a burst duration (BD), which is the value of the time difference between the ultrasonic burst start (UBS) and the ultrasonic burst end (UBE). In this disclosure, it is now proposed that the ultrasonic burst (UB) be temporally divided into a first burst phase (t 1a ) and a second burst phase (t 1b) by a first half-frequency time (t 1 / 50% ). The first half-frequency time (t 1 / 50% ) the time within the transmission time of an ultrasonic burst (UB) at which the instantaneous ultrasonic frequency (f m ) of the first upper half-maximum amplitude frequency (f 1o ) or the first lower half-maximum amplitude frequency (f 1u ). At the first upper half-maximum amplitude frequency (f 1o ) the amplitude (A) of the sound radiation of the first ultrasonic transducer (US1) is half of the first amplitude maximum (A max1 ) of the sound radiation of the first ultrasonic transducer (US1) at its first resonance frequency (f1). The first upper half-maximum amplitude frequency (f 1o ) of the first ultrasonic transducer (US1) is above the first resonance frequency (f1) of the first ultrasonic transducer (US1). At the first lower half-maximum amplitude frequency (f1u ), the amplitude (A) of the sound radiation of the first ultrasonic transducer (US1) is also half of the first amplitude maximum (A max1 ) of the sound radiation of the first ultrasonic transducer (US1) at its first resonance frequency (f1). The first lower half-maximum amplitude frequency (f 1u ) of the first ultrasonic transducer (US1) is below the first resonance frequency (f1) of the first ultrasonic transducer (US1).

[0030] This method is characterized by the fact that the amount of the mean rate of change (v f ) of the instantaneous ultrasonic frequency (f m ) in the first burst phase (t 1a ) of the amount of the mean rate of change (v f ) of the instantaneous ultrasonic frequency (f m ) in the second burst phase (t 1b) preferably by more than 10% and / or better by more than 20% and / or better by more than 50% and / or better by more than 100%.

[0031] Preferably, the first burst phase (t 1a ) has a temporal length that depends on the temporal length of the second burst phase (t 1b ) by more than 10% and / or by more than 20% by more than 50% by more than 100%.

[0032] Likewise preferred is the length of the first burst phase (t 1a ) by more than 10% and / or by more than 20% by more than 50% by more than 75% shorter than the length of the second burst phase (t 1b ).

[0033] This method can be used, as proposed, for several instantaneous ultrasonic frequencies (f m1 , f m2) are carried out simultaneously, which provides additional information about any objects that may be in the vicinity of the vehicle. This is then a method for emitting an ultrasonic signal, wherein the ultrasonic signal has an overall ultrasonic burst (UB) and wherein the overall ultrasonic burst (UB) comprises a first overall ultrasonic burst and wherein the overall ultrasonic burst (UB) comprises a second overall ultrasonic burst. Each overall ultrasonic burst of the overall ultrasonic bursts has at least two, typically considerably more, ultrasonic pulses (P0 to P7). Each of the at least two ultrasonic pulses (P0 to P7) of an overall ultrasonic burst again has a temporal ultrasonic pulse start and a temporal ultrasonic pulse end.The ultrasonic period (T1 to T7) of a single ultrasonic pulse (P0 to P7) of an ultrasonic subburst, hereinafter referred to as the respective ultrasonic pulse, is again the time from the temporal ultrasonic pulse end of the ultrasonic pulse immediately preceding the respective ultrasonic pulse to the temporal ultrasonic pulse end of the respective ultrasonic pulse. The first instantaneous ultrasonic frequency (f. 1m ) of the first ultrasonic subburst is the inverse of the current ultrasonic period (T 1m ) of the first ultrasonic subburst. The second ultrasonic instantaneous frequency (f 2m ) of the second ultrasonic subburst is the inverse of the instantaneous ultrasonic period (T 2m ) of the second ultrasonic subburst. The first ultrasonic subburst begins at a first start time (t 1s), which is equal to the start of the first ultrasonic pulse (P0) of the first ultrasonic subburst. The first ultrasonic subburst ends at a first end time (t 1e ), which is equal to the end of the last ultrasonic pulse (P7) of the first ultrasonic subburst. The first ultrasonic subburst has a first ultrasonic subburst duration (t 1e -t 1s ), which is the value of the time difference between the first end time (t 1e ) minus the first start time (t 1s ). The second ultrasonic subburst begins at a second starting time (t 2s ), which is equal to the start of the first ultrasonic pulse (P0) of the second ultrasonic subburst. The second ultrasonic subburst ends at a second end time (t 2e), which is equal to the end of the last ultrasonic pulse (P7) of the second ultrasonic subburst. The second ultrasonic subburst has a second ultrasonic subburst duration (t 2e -t 2s ), which is the value of the time difference between the second end time (t 2e ) minus the second starting time (t 2s ). This method variant is characterized by the fact that the first instantaneous ultrasonic frequency (f 1m ) from the second instantaneous ultrasonic frequency (f 2m ) at least one time between the first start time (t 1s ) and the first end time (t 1e ) and simultaneously between the second starting time (t 2s ) and the second end time (t 2e ) is different. Therefore, two instantaneous ultrasonic frequencies (fm1, fm2) are always emitted by the ultrasonic sensor system (USS).

[0034] A first variant of the method provides that the second starting time (t 2s ) in time between the first start time (t 1s ) and the first end time (t 1e ) and / or that the second starting time (t 2s ) is equal to the first starting time (t 1s ) is.

[0035] In another variant, the second end time (t 2e ) in time between the first start time (t 1s ) and the first end time (t 1e ) and / or the second end time (t 2e ) is equal to the first end time (t 1e ).

[0036] In some applications it may be useful to set the first instantaneous ultrasonic frequency (f 1m ) to the first end time (f 1e ) equal to the second instantaneous ultrasonic frequency (f 2m ) to the second end time (f 2e ) is.

[0037] In other applications, it may be useful if the first instantaneous ultrasonic frequency (f 1m ) at the first start time (f 1s ) equal to the second instantaneous ultrasonic frequency (f 2m ) to the second starting time (f 2s ) is.

[0038] In other applications, it may be useful if the first instantaneous ultrasonic frequency (f 1m ) at the first start time (f 1s ) different from the second instantaneous ultrasonic frequency (f 2m ) to the second starting time (f 2s ) is.

[0039] And in other applications it may be useful if the first instantaneous ultrasonic frequency (f 1m ) to the first end time (f 1e ) different from the second instantaneous ultrasonic frequency (f 2m ) to the second end time (f 2e ) is.

[0040] A method for transmitting an ultrasonic signal developed from the above methods comprises the steps a. generating the first ultrasonic subburst with a first ultrasonic transducer (UBS1) and / or b. generating the second ultrasonic subburst with a second ultrasonic transducer (UBS2) which is different from the first ultrasonic transducer (UBS1).

[0041] Preferably, the first ultrasonic transducer (US1) has a first resonance frequency (f1) and the second ultrasonic transducer (US2) has a second resonance frequency (f2), wherein the first resonance frequency (f1) of the first ultrasonic transducer (US1) is different from the second resonance frequency (f2) of the second ultrasonic transducer (US2). This allows additional information to be used for object classification of the objects (O).

[0042] The first ultrasonic transducer (US1) preferably has a first bandwidth (Δf1) with a first upper half-maximum amplitude frequency (f 1o ) and a first lower half-maximum amplitude frequency (f 1u ). The second ultrasonic transducer (US1) preferably has a second bandwidth (Δf2) with a second upper half-maximum amplitude frequency (f 2o ) and a second lower half-maximum amplitude frequency (f 2m ). The first bandwidth (Δf1) and the second bandwidth (Δf2) overlap in the frequency domain. This has the advantage that a frequency sweep can be performed over a larger frequency range. It is therefore preferable that a. the difference of the magnitude of the first upper half-maximum amplitude frequency (f 1o ) minus the magnitude of the second lower half-maximum amplitude frequency (f 2m ) is preferably greater than the difference of the magnitude of the first upper half-maximum amplitude frequency (f1o ) minus the magnitude of the first lower half-maximum amplitude frequency (f 1u ) and / or b. the difference of the magnitude of the first upper half-maximum amplitude frequency (f 1o ) minus the magnitude of the second lower half-maximum amplitude frequency (f 2m ) is preferably greater than the difference in the magnitude of the second upper half-maximum amplitude frequency (f 2o ) minus the magnitude of the second lower half-maximum amplitude frequency (f 2m ) or c. the difference of the magnitude of the second upper half-maximum amplitude frequency (f 2o ) minus the magnitude of the first lower half-maximum amplitude frequency (f 1u ) is preferably greater than the difference of the magnitude of the first upper half-maximum amplitude frequency (f 1o ) minus the magnitude of the first lower half-maximum amplitude frequency (f 1u ) and / or d. the difference of the magnitude of the second upper half-maximum amplitude frequency (f 2o ) minus the magnitude of the first lower half-maximum amplitude frequency (f 1u ) is preferably greater than the difference of the magnitude of the first upper half-maximum amplitude frequency (f 1o ) minus the magnitude of the first lower half-maximum amplitude frequency (f 1u ).

[0043] Furthermore, it is advantageous if the angle-dependent first energy density of the first sound emission of the first ultrasonic transducer (US1) differs from the angle-dependent second energy density of the second sound emission of the second ultrasonic transducer (US2) and / or the angle-dependent first sound amplitude of the first sound emission of the first ultrasonic transducer (US1) differs from the angle-dependent second sound amplitude of the second sound emission of the second ultrasonic transducer (US2). As explained in the figures, this allows information about the angular range and the distance of an object (O1, O2) to be obtained from the reflection signal.

[0044] In addition to the methods for transmitting ultrasonic bursts described so far, there are also analogous methods for receiving the ultrasonic bursts.

[0045] The ultrasonic signal that is now received, which was typically previously reflected by an object, was preferably generated using one of the previously described methods. The complex structure of the ultrasonic signals is discussed in more detail in the figure descriptions. Therefore, it is recommended to briefly glance over the figures with the frequency curves to understand which type of ultrasonic bursts are to be received. A first ultrasonic transducer (US1) and a second ultrasonic transducer (US2) are to be part of a common ultrasonic sensor system (USS). The ultrasonic sensor system (USS) is to have an ultrasonic system axis (USA). The method for receiving the complex ultrasonic bursts comprises the steps a. receiving the reflected ultrasonic signal with a first ultrasonic transducer (US1) as the first ultrasonic reception signal, wherein the first ultrasonic transducer has a first resonance frequency (f1), and b. receiving the reflected ultrasonic signal with a second ultrasonic transducer (US2) as a second ultrasonic reception signal, wherein the second ultrasonic transducer (US2) has a second resonance frequency (f2), and c. processing the first ultrasonic reception signal and the second ultrasonic reception signal and d. inferring distances from objects (O1, O2) that have reflected the ultrasonic signal to the common ultrasonic system (USS) and e. inferring an angle between the line of sight from the common ultrasound system (USS) to objects (O1, O2) that have reflected the ultrasound signal, on the one hand, and the ultrasound system axis (USA) of the common ultrasound system (USS) on the other hand, or inferring an angular range in which the objects (O1, O2) are respectively located.

[0046] From what has been written so far, a method for determining an object position results, the implementation of a method with the aid of the different sound cones of the different ultrasound transducers (US1-US2, US3) with the aid of a first common ultrasound system (USS1) for determining a first distance (s1) and a first angle or first angular range and the analogous implementation of this method with the aid of a preferably, but not necessarily identical, second common ultrasound system (USS2), which is different from the first common ultrasound system (USS1) - i.e. not identical to it - and spaced apart, for determining a second distance (s2) and a second angle or a second distance and second angular range.According to this method, a spatial coordinate or a spatial region in which an object (O) is located that has reflected the ultrasonic signal is then determined on the basis of the first distance (s1) and the second distance (s2), as well as the determined first angular range and the determined second angular range. The information corresponding to the first angular range and the first distance (s1) corresponds to a first spatial region approximately in the shape of a first torus at the first distance from the first ultrasonic sensor system (USS1). The information corresponding to the second angular range and the second distance (s1) corresponds to a second spatial region approximately in the shape of a second torus at the second distance from the second ultrasonic sensor system (USS2).The intersection of the spatial points that are located within both the first spatial area and the second spatial area results in a smaller additional spatial area in which the object in question should be located.

[0047] Furthermore, another method for transmitting an ultrasonic burst for use in ultrasonic sensor systems in vehicles is disclosed, which comprises the following steps: - Step 1: Emission of an ultrasonic burst with an ultrasonic burst duration (bd) not exceeding a maximum ultrasonic burst duration (bd) by an ultrasonic sensor system (USS); - Step 2: Receiving an ultrasonic burst reflected by an object (O); - Step 3: Determining the distance (D) between the ultrasonic sensor system (USS) and the object (O) as a function of the received reflected ultrasonic burst; - Step 4: Repeat steps 1 to 4, whereby the ultrasonic burst duration (bd) depends on the determined distance (D, s1, s2).

[0048] It has been shown that it is advantageous if the ultrasonic burst length of the ultrasonic burst duration (bd) is multiplied by the fourth root of the determined distance (D) according to the formula bd=bd1*D−1 / 4+bd0 with bd0 and bd1 as constants is extended in time, i.e., its magnitude is increased. This has the advantage that the total energy that returns to the emitting ultrasound transducer upon reflection allows conclusions to be drawn about the object, since this amount of energy no longer depends on the distance, but only on the size and reflectivity of the object. It is sufficient if such ultrasound pulses, corrected for the burst length (bd), are emitted from time to time. For example, if several objects have been located at different distances, it may be useful to emit an ultrasound burst (UB) for each detected object, optimized for the distance to that object.

[0049] This then results in a method for emitting an ultrasonic burst for use in ultrasonic sensor systems in vehicles, comprising the steps: - Step 1: Emitting an ultrasonic burst having an ultrasonic burst characteristic by an ultrasonic sensor system (USS); - Step 2: Receiving an ultrasonic burst reflected by an object (O); - Step 3: Determining and evaluating a property of the object (O) as a function of the received reflected ultrasonic burst and / or possibly several received reflected ultrasonic bursts; - Step 4: Repeating steps 1 to 4, wherein at least one ultrasonic burst property of a subsequently emitted ultrasonic burst depends on the evaluation of the determined property.

[0050] It is important that one of the subsequently emitted ultrasonic bursts does not have to follow immediately on the preceding ultrasonic burst. Rather, it is conceivable to send further ultrasonic bursts with different measuring tasks between these two ultrasonic bursts. Such sequences of ultrasonic bursts can be mixed. Thus, the ultrasonic burst property of an ultrasonic burst to be emitted can depend on one or more objects in the vicinity of the ultrasonic sensor system (USS) or the environment of the ultrasonic sensor system (USS). Thus, the ultrasonic burst property of an ultrasonic burst to be emitted can depend on one or more objects in the vicinity of a vehicle or the environment of the vehicle if such an ultrasonic sensor system (USS) is installed in the vehicle. Several ultrasonic burst properties are described below, which can also affect the properties of several ultrasonic bursts.

[0051] This may then result, for example, in a method for emitting an ultrasonic burst for use in ultrasonic sensor systems in vehicles, which comprises the following steps: - Step 1: Emitting a first ultrasonic burst having an ultrasonic burst characteristic with a first ultrasonic burst characteristic value by an ultrasonic sensor system (USS); - Step 2: Receiving a first ultrasonic burst reflected by a first object (O); - Step 3: Determining and evaluating a first property of the first object (O1) as a function of the received reflected first ultrasonic burst and / or possibly a plurality of received reflected first ultrasonic bursts; - Step 4: Emission of a second ultrasonic burst with the ultrasonic burst property with a second ultrasonic burst property value by the ultrasonic sensor system (USS); - Step 5: Receiving a second ultrasonic burst reflected by a second object (O); - Step 6: Determining and evaluating a second property of the second object (O2) as a function of the received reflected second ultrasonic burst and / or possibly a plurality of received reflected second ultrasonic bursts; - Step 7: Repeat steps 1 to 6, • wherein at least the first ultrasonic burst property of a subsequently emitted first ultrasonic burst depends on the evaluation of the determined first property and ▪ wherein at least the second ultrasonic burst property of a subsequently emitted second ultrasonic burst depends on the evaluation of the determined second property.

[0052] It's important to note that additional ultrasonic bursts can be inserted for other purposes. The first ultrasonic bursts can also be emitted more or less frequently than the second ultrasonic bursts.

[0053] Just as the ultrasonic burst duration (bd) can be optimized depending on the object, the ultrasonic burst amplitude can also be optimized depending on the object. Thus, it may be useful if the amplitude (A) of at least three ultrasonic bursts emitted in immediate or non-immediate temporal sequence is essentially proportional to (D+D0). 1 / k , with 2≤k≤5 or preferably k=2 or k=4, depends on the determined distance (D), where D0 is a constant that can be zero. Between these ultrasonic bursts (UB), additional ultrasonic bursts (UB) can be emitted to measure other objects and environmental properties.

[0054] Typically, several ultrasonic bursts (UB) are emitted at a temporal ultrasonic burst interval, wherein the first temporal ultrasonic burst interval is the temporal interval between the ultrasonic burst start (UBS) of a first ultrasonic burst and the ultrasonic burst start (UBS) of the second ultrasonic burst immediately following this first ultrasonic burst, and wherein the second temporal ultrasonic burst interval between the ultrasonic burst start (UBS) of the second ultrasonic burst and the ultrasonic burst start (UBS) of the third ultrasonic burst immediately following this second ultrasonic burst depends on the determined distance (D) of an object (O, O, O2).

[0055] Another possible variation of an ultrasonic burst property is a variation of the temporal ultrasonic burst spacing of the ultrasonic bursts. The temporal ultrasonic burst spacing of the ultrasonic bursts can, for example, become shorter with decreasing spatial distance (D) between the ultrasonic sensor system and the object (O). Preferably, the temporal ultrasonic burst spacing of the ultrasonic bursts is shortened by a time 2*I / c, with c being the speed of sound, with a tolerance of + / - 25% and / or better with a tolerance of + / - 10% and / or better with a tolerance of + / - 5% when the spatial distance (D) between the ultrasonic sensor system and the object (O) is shortened by a length I.

[0056] As a further variation of an ultrasonic burst property, the number of ultrasonic burst instantaneous frequencies (f m1 , f m2 , f m3) and the corresponding number of frequency responses (SF1, SF2, SF3) of these ultrasonic burst instantaneous frequencies (f m1 , f m2 , f m3 ) within an ultrasonic burst (UB) depend on the distance (D).

[0057] A further modification of an ultrasonic burst property may be that an ultrasonic burst has at least two of the following time period types: • a single-mode time (smt1, smt2, smt3, smt1, smt2) and / or • a dual-mode time (dmt 12 , dmt 23 , dmt1, dmt2) and / or • a tri-mode time (t mt , tmt 123 , tmt 112 ).

[0058] This ultrasonic burst property can also depend on objects in the surroundings or the environment in part or as a whole. Such ultrasonic sensor systems are preferably used in vehicles. In this case, it is preferably an ultrasonic sensor system (USS) for a vehicle, with a first ultrasonic transducer (US1) and a second ultrasonic transducer (US2). Of course, the ultrasonic sensor system can also have more than two ultrasonic transducers (US1, US2, US3). In our example, the first ultrasonic transducer (US1) has a first resonant frequency (f1) and the second ultrasonic transducer (US2) has a second resonant frequency (f2), wherein the first resonant frequency (f1) is different from the second resonant frequency (f2).

[0059] Preferably, the first ultrasonic transducer (US1) has a first bandwidth (Δf1) and the second ultrasonic transducer (US2) has a second bandwidth (Δf2). To ensure that a chirp can be performed across the full bandwidth without significant amplitude drops, it is advantageous for the first bandwidth (Δf1) of the first ultrasonic transducer (US1) and the second bandwidth (Δf2) of the second ultrasonic transducer (US2) to overlap.

[0060] Preferably, the ultrasonic sensor system (USS) is designed such that the ultrasonic sensor system (USS) generates an ultrasonic burst (UB) with an ultrasonic burst instantaneous frequency (f m) that cannot be emitted by an ultrasonic transducer of the ultrasonic transducers (US1, US2) of the ultrasonic sensor system (USS) at at least one point in time during the emission of the ultrasonic burst (UB). This thus describes an increase in the bandwidth compared to a single ultrasonic transducer with regard to emission.

[0061] Analogously, the ultrasonic sensor system (USS) is preferably designed in such a way that the ultrasonic sensor system (USS) generates an ultrasonic burst (UB) with an ultrasonic burst instantaneous frequency (f m ) that cannot be received by an ultrasonic transducer of the ultrasonic transducers (US1, US2) of the ultrasonic sensor system (USS) at at least one time during the transmission of the ultrasonic burst (UB). This thus describes an increase in bandwidth compared to a single ultrasonic transducer with regard to reception.

[0062] Preferably, the ultrasonic sensor system (USS) can emit an ultrasonic burst (UB) having more than one ultrasonic burst instantaneous frequency (f m1 , f m2 , f m3 ) in its spectrum, with each of the ultrasonic burst instantaneous frequencies (f m1 , f m2 , f m3 ) during such an ultrasonic burst lies essentially within the bandwidth (Δf1, Δf2, Δf3) of at least one of the ultrasonic transducers (US1, US2, US3). This is also an ultrasonic burst property that can depend on the target of investigation, typically an object (O, O1, O2) in the vicinity of the ultrasonic sensor system or the vehicle. Conversely, the ultrasonic sensor system (USS) can then typically receive an ultrasonic burst (UB) that has more than one ultrasonic burst instantaneous frequency (f m1 , f m2 , f m3 ) in its spectrum, with each of the ultrasonic burst instantaneous frequencies (f m1 , fm2 , f m3 ) during such an ultrasonic burst lies essentially within the bandwidth (Δf1, Δf2, Δf3) of at least one of the ultrasonic transducers (US1, US2, US3). Preferably, the output signals of the ultrasonic transducers are then combined into an ultrasonic reception signal. In the simplest case, this can be achieved, for example, by summing the output signals of the ultrasonic transducers.

[0063] An ultrasonic sensor system (USS) is also conceivable in which the ultrasonic sensor system (USS) can receive an ultrasonic burst (UB) that has more than one ultrasonic burst instantaneous frequency (f m1 , f m2 , f m3 ) in its spectrum at least at one time during the burst duration (bd), where each of the ultrasonic burst instantaneous frequencies (f m1 , f m2 , f m3) during such an ultrasonic burst lies essentially in the bandwidth (Δf1, Δf2, Δf3) of at least one of the ultrasonic transducers (US1, US2, US3) and wherein then at least one of these ultrasonic burst instantaneous frequencies (f m1 , f m2 , f m3 ) during such an ultrasonic burst is not within the bandwidth (Δf1, Δf2, Δf3) of at least one of the ultrasonic transducers (US1, US2, US3) at at least one time. Thus, the use of multiple ultrasonic transducers results in an increase in the reception bandwidth.

[0064] In one possible configuration, multiple ultrasonic transducers (US1, US2) of an ultrasonic sensor system (USS) are driven by a common control signal (AS). This has the advantage that such an ultrasonic sensor system (USS) essentially behaves like a single ultrasonic transducer for control circuits.

[0065] Similarly, a common ultrasonic reception signal can be generated from the output signals of the ultrasonic transducers (US1, US2), which may also have several sub-signals.

[0066] Such an ultrasonic sensor system (USS) can be designed so that the sound beam of the first ultrasonic transducer (US1) has a first vertical opening angle (α v ) and the sound beam of the second ultrasonic transducer (US2) has a second vertical opening angle (β v ) or that the receiving lobe of the first ultrasonic transducer (US1) has a first vertical opening angle (α v ) and the receiving lobe of the second ultrasonic transducer (US2) has a second vertical opening angle (β v ) . The first vertical opening angle (α v ) from the second vertical opening angle (β v) so that a reflected ultrasonic signal has different frequencies that encode the angular range around the axis (USA) of the ultrasonic sensor system (USS) in which the reflecting object may be located.

[0067] In an analogous manner, the sound beam of the first ultrasonic transducer (US1) has a first horizontal opening angle (α H ) and the sound beam of the second ultrasonic transducer (US2) has a second vertical opening angle (β v ) or the receiving lobe of the first ultrasonic transducer (US1) has a first horizontal opening angle (α H ) and the receiving lobe of the second ultrasonic transducer (US2) has a second vertical opening angle (β v ). Here, too, the first horizontal opening angle (α H ) from the second vertical opening angle (β v ) are different, which results in an analogous advantage.

[0068] Most preferably, the proposed ultrasonic sensor system comprises further ultrasonic transducers in addition to the first ultrasonic transducer (US1) and the second ultrasonic transducer (US2), resulting in an ultrasonic transducer array in which the ultrasonic transducers (US1, US2, US3) have different resonant frequencies (f1, f2, f3). In the simplest case, the proposed ultrasonic sensor system comprises a third ultrasonic transducer (US3) in addition to the first ultrasonic transducer (US1) and the second ultrasonic transducer (US2), wherein the third ultrasonic transducer (US3) has a third resonant frequency (f3), which is preferably different from the second resonant frequency (f2) and the first resonant frequency (f1).

[0069] In this case with three ultrasonic transducers (US1, US2, US3), the ultrasonic transducers (US1, US2, US3) are preferably arranged in an isosceles triangle. The edge lengths of this isosceles triangle are preferably less than ten times the diameter of the sound emitting surfaces of the ultrasonic transducers (US1, US2, US3) and / or better still, less than five times the diameter of the sound emitting surfaces of the ultrasonic transducers (US1, US2, US3) and / or better still, less than three times the diameter of the sound emitting surfaces of the ultrasonic transducers (US1, US2, US3) and / or better still, less than twice the diameter of the sound emitting surfaces of the ultrasonic transducers (US1, US2, US3).

[0070] In an analogous manner, a method for receiving an ultrasonic signal results, wherein the ultrasonic signal comprises an overall ultrasonic burst (UB) comprising a first ultrasonic subburst and a second ultrasonic subburst. Here, too, each ultrasonic subburst of the ultrasonic subbursts comprises at least two ultrasonic pulses (P0 to P7), of which each of the at least two ultrasonic pulses (P0 to P7) of an ultrasonic subburst has a temporal ultrasonic pulse start and a temporal ultrasonic pulse end. As before, the ultrasonic period (T1 to T7) of an individual ultrasonic pulse (P0 to P7) of an ultrasonic subburst, hereinafter referred to as the respective ultrasonic pulse, is the time from the temporal ultrasonic pulse end of the ultrasonic pulse immediately preceding the respective ultrasonic pulse to the temporal ultrasonic pulse end of the respective ultrasonic pulse. The first instantaneous ultrasonic frequency (f 1m) of the first ultrasonic subburst is again the inverse of the current ultrasonic period (T 1m ) of the first ultrasonic subburst and the second ultrasonic instantaneous frequency (f 2m ) of the second ultrasonic subburst is again the inverse of the current ultrasonic period (T 2m ) of the second ultrasonic subburst. The first ultrasonic subburst begins at a first start time (t 1s ), which is equal to the start of the first ultrasonic pulse (P0) of the first ultrasonic subburst. The first ultrasonic subburst ends at a first end time (t 1e ), which is equal to the end of the last ultrasonic pulse (P7) of the first ultrasonic subburst. The first ultrasonic subburst has a first ultrasonic subburst duration (t 1e -t 1s ), which corresponds to the value of the time difference between the first end time (t 1e ) minus the first start time (t 1s). The second ultrasonic subburst begins at a second starting time (t 2s ), which is equal to the start of the first ultrasonic pulse (P0) of the second ultrasonic subburst. The second ultrasonic subburst ends at a second end time (t 2e ), which is equal to the end of the last ultrasonic pulse (P7) of the second ultrasonic subburst. The second ultrasonic subburst has a second ultrasonic subburst duration (bd=t 2e -t 2s ), which corresponds to the value of the time difference between the second end time (t 2e ) minus the second starting time (t 2s ). The first instantaneous ultrasonic frequency (f 1m ) is preferably determined by the second instantaneous ultrasonic frequency (f 2m ) at least one time between the first start time (t 1s ) and the first end time (t 1e ) and simultaneously between the second starting time (t2s ) and the second end time (t 2e ) is different. The reception process then includes the following steps: • Receiving the total ultrasound burst (UB) by means of an ultrasound sensor system (USS) with at least a first ultrasound transducer (US1) and a second ultrasound transducer (US2), wherein the first ultrasound transducer (US1) has a first resonance frequency (f1) and a first bandwidth (Δf1) and wherein the second ultrasound transducer (US2) has a second resonance frequency (f2) and a second bandwidth (Δf2) and wherein the first resonance frequency (f1) is different from the second resonance frequency (f2) and wherein the first bandwidth (Δf1) overlaps the second bandwidth (Δf2) and wherein the first ultrasound transducer (US1) generates a first ultrasound reception sub-signal and wherein the second ultrasound transducer (US2) generates a second ultrasound reception sub-signal; • Generating an ultrasonic reception signal from the first ultrasonic reception sub-signal and the second ultrasonic reception sub-signal, wherein the ultrasonic reception signal may comprise a plurality of sub-reception signals and wherein one or more sub-reception signals may correspond to ultrasonic reception sub-signals; • Determining environmental information based on the ultrasonic reception signal.

[0071] Typically, at least at one point in time during the burst duration (bd) of the total ultrasound burst, the first instantaneous ultrasound frequency (f 1m ) is not within the first bandwidth (Δf1) of the first ultrasonic transducer (US1), but within the second bandwidth (Δf2) of the second ultrasonic transducer (US2), and / or the first instantaneous ultrasonic frequency (f 1m) not within the second bandwidth (Δf2) of the second ultrasonic transducer (US2), but within the first bandwidth (Δf1) of the first ultrasonic transducer (US1), the second ultrasonic instantaneous frequency (f 2m ) is not within the first bandwidth (Δf1) of the first ultrasonic transducer (US1), but within the second bandwidth (Δf2) of the second ultrasonic transducer (US2), and / or the second instantaneous ultrasonic frequency (f 2m ) not within the second bandwidth (Δf2) of the second ultrasonic transducer (US2) but within the first bandwidth (Δf1) of the first ultrasonic transducer (US1).

[0072] A refinement of the method may include the step of inferring a distance to an object (O1, O2) and an angular range in which this object (O1, O2) is located based on differences between the first ultrasonic reception sub-signal and the second ultrasonic reception sub-signal or based on differences in signals derived from them. In particular, neural networks or other pattern recognition methods may be used for this purpose.

[0073] The method for receiving an ultrasonic total burst may be characterized in that a received ultrasonic total burst has at least two of the following time period types: • a single-mode time (smt1, smt2, smt3, smt1, smt2) and / or • a dual-mode time (dmt 12 , dmt 23 , dmt1, dmt2) and / or • a tri-mode time (t mt , tmt 123 , tmt 112 )

[0074] Under this condition, the procedure may include, among other steps: • Receiving the total ultrasonic burst and generating said ultrasonic reception signal, which may comprise a plurality of partial reception signals; • Determining the first time segment type at a first time within the burst duration (bd) of the total ultrasound burst; • Determining environmental information based on the ultrasonic reception signal depending on the first time period type detected.

[0075] This procedure can be refined by including the following steps: • Determining the second time period type at a second time within the burst duration (bd) of the total ultrasound burst which is different from the first time; • Determining environmental information on the basis of the ultrasound reception signal depending on the determined first time period type within a first time period within the burst duration (bd) of the total ultrasound burst; • Determining environmental information on the basis of the ultrasonic reception signal depending on the detected second time period type within a second time period within the burst duration (bd) of the total ultrasonic burst,

[0076] The first and second time periods should preferably not overlap. At the very least, they should not completely overlap.

[0077] This document has consistently referred to ultrasound transducers. It is obvious to a person skilled in the art that, with regard to the transmission of the total ultrasound bursts, ultrasound transmitters can also be used which are only used and / or suitable for transmitting the total ultrasound bursts. It is likewise obvious to a person skilled in the art that, with regard to the reception of the total ultrasound bursts, ultrasound receivers can also be used which are only used and / or suitable for receiving the total ultrasound bursts. In this respect, the claims with regard to reception also include combinations of ultrasound transducers with one or more pure ultrasound receivers using the term "ultrasound transducer", and with regard to the transmission of total ultrasound bursts, the term "ultrasound transducer" also includes combinations of ultrasound transducers with one or more pure ultrasound transmitters.

[0078] In extreme cases, these may only be pure ultrasound receivers or pure ultrasound transmitters.

[0079] For example, it is conceivable to combine one or a few ultrasonic transducers used for transmitting and receiving with a larger number of pure ultrasonic receivers. The pure ultrasonic receivers can be manufactured inexpensively using MEMS, while the ultrasonic transmitters, in the form of ultrasonic transducers, can be constructed using piezo-based vibrating ceramics.

[0080] On this basis, an ultrasonic sensor system (USS) can then be defined, in particular for a vehicle or a robot or another movable machine, which has a first, typically smaller number of ultrasonic transmitters and / or ultrasonic transducers, each having a piezoceramic as a sound-generating transmitting element, and which comprises a second number of pure ultrasonic receivers. Preferably, at least one of these ultrasonic receivers is a MEMS-based ultrasonic receiver. Very particularly preferably, the number of pure MEMS ultrasonic receivers is particularly high. Preferably, at least some of the ultrasonic transmitters and / or ultrasonic transducers and / or ultrasonic receivers form an ultrasonic system, as described above. Advantage

[0081] Such an ultrasonic sensor system (USS) enables, at least in some implementations, the transmission and / or reception of more complex ultrasonic bursts than those possible with individual ultrasonic transducers and / or transmitters. This is particularly important in the creation of environment maps and point clouds for autonomous driving. However, the advantages are not limited to this. List of characters Fig. 1a as part of the Fig. Figure 1 shows the course of the ultrasound burst amplitude (A) as a function of the burst duration (bd). Fig. 1b as part of the Fig. 1 shows a suggested burst duration depending on the object distance (D) to the nearest object. Fig. 1c as part of the Fig. Figure 1 shows the ultrasonic burst amplitude (A) as a function of the object distance (D). Fig. Figure 2a shows a simplified schematic of the temporal signal curve of a single, selected exemplary ultrasonic burst (UB). Fig. Figure 2b shows the corresponding time course of the ultrasonic burst instantaneous frequency (f m ) plotted against time (t) over the burst duration (bd). Fig. 2c Fig. 2c shows an example of the frequency change rate (v f ) of the ultrasonic burst instantaneous frequency (f m ) over time (t) of the burst duration (bd). Fig. 3 shows an exemplary first spectral ultrasonic burst amplitude (A1) of a first ultrasonic transducer (US1) for the amplitude (A) of the sound radiation of this ultrasonic transducer (US1) when excited with a first excitation signal with the first excitation frequency (f A1 ). Fig. 4 shows an exemplary second spectral ultrasonic burst amplitude (A2) for the amplitude (A) of the sound radiation of a second ultrasonic transducer (US2) when excited with a second excitation signal (AS2) with the second excitation frequency (f A2 ). Fig. 5 Fig. 5 shows an exemplary third spectral ultrasonic burst amplitude (A3) for the amplitude (A) of the sound radiation of a third ultrasonic transducer (US3) when excited with a transmission signal of the third excitation frequency (fA3). Fig. 6 Fig. Figure 6 shows, as an example, two extreme configurations of the superposition of a first, second and third amplitude spectrum. Fig. Figures 7 to 10 show possible types of frequency sweeps. Fig. 11 shows an exemplary arrangement consisting of a first ultrasonic transducer (US1) and a second ultrasonic transducer (US2) and a third ultrasonic transducer (US3). Fig. 12 corresponds to the Fig. 7 with the difference that now a frequency sweep is generated using three ultrasonic sensors (US1, US2, US3). Fig. 13 shows a simplified and schematic illustration of an exemplary system for generating the exemplary frequency response of the Fig. 12. Fig. 14 corresponds in essential parts to the Fig. 12, but now the excitation signal (AS) temporarily comprises more than one excitation frequency (fA). Fig. 15 shows a simplified and schematic illustration of an exemplary system for generating the exemplary frequency response of the following Fig. 16. Fig. 16 corresponds to the Fig. 12 with the difference that now a first frequency response (SF1), a second frequency response (SF2) and a third frequency response (SF3) are used together to generate an ultrasonic burst (UB). Fig. 17 corresponds to the Fig. 16 with the difference that now all frequency curves (SF1, SF2, SF3) are at a common end frequency (f e ) as the respective instantaneous ultrasonic frequency (f m1 , f m2 , f m3 ) to a common end time (t e ) end. Fig. 18 and Fig. 19 The sound radiation of an ultrasonic sensor system (USS) with different resonance frequencies and aperture angles. Fig. Figure 20 illustrates how the different types of modulation described above can now be used when approaching an important object (O), for example an obstacle. Fig. 21 illustrates the situation when using two ultrasonic sensor systems (USS1, USS2) Fig. Figure 22 shows the course of the instantaneous ultrasound frequencies and their effect on the Doppler strength. Description of the figuresFigure 1

[0082] Fig. 1 shows in Fig. 1a the course of the ultrasonic burst amplitude (A) as a function of the burst duration (bd) (see also Fig. 2). As the ultrasonic burst lengthens, i.e., the burst duration (bd) increases, the ultrasonic burst amplitude (A) decreases.

[0083] Fig. Figure 1b shows a suggested burst duration as a function of the object distance (D) to the nearest object. The burst duration is not only increased with increasing object distance (D). Preferably, the ultrasonic burst length of the ultrasonic burst duration (BD) increases with the square root or the fourth root of the object distance (D). This increases the latency. However, the increase in the signal reflected by the object is achieved in such a way that the signal proportional to 1 / D 4 reduction of the reception amplitude to a reduction of 1 / D 2 Even more preferably, the ultrasonic burst length is the ultrasonic burst duration (bd) with the fourth root of the distance according to the formula bd=bd1*D -1 / 4 +bd0 with bd0 and bd1 as constants. This ensures that the total signal amplitude remains constant for the object being measured after reception and correlation in a correlator.

[0084] To avoid overloading in close range, the burst duration (bd) is not only reduced near the object. Preferably, the ultrasonic burst amplitude is also reduced near the object. This allows the reception amplitude to be kept constant after reception and correlation, even when shortening the burst duration (bd) is no longer appropriate. Therefore, it is proposed here to adjust the burst duration of the ultrasonic bursts and the ultrasonic burst amplitude (A) so that the reception amplitude of the observed object remains constant or follows a predefined sensitivity curve. Fig. Figure 1c shows the ultrasonic burst amplitude (A) as a function of the object distance (D). Figure 2

[0085] Fig. Figure 2a shows a simplified schematic of the temporal signal profile of a single, selected example ultrasonic burst (UB). The ultrasonic burst (UB) begins at the time of the ultrasonic burst start (UBS). The ultrasonic burst (UB) ends at the time of the ultrasonic burst end (UBE). The time between the ultrasonic burst start (UBS) and the ultrasonic burst end (UBE) is the burst duration (BD). The ultrasonic burst (UB) has an ultrasonic burst amplitude (A), which can be understood here as the average amplitude of the ultrasonic burst (UB) over the burst duration (BD) of the respective ultrasonic burst (UB).

[0086] In the example of Fig. 2a, the ultrasonic burst (UB) shown there has eight ultrasonic periods, each with one ultrasonic pulse, i.e., in this example, eight ultrasonic pulses (P0 to P7). The zeroth ultrasonic pulse (P0) is assigned to the only half-existent zeroth ultrasonic period. The ultrasonic periods (P0 to P7) of the ultrasonic burst (UB) have eight ultrasonic period durations (T0 to T7). The zeroth ultrasonic period duration (T0) is defined in this document as twice the temporal pulse width of the zeroth ultrasonic pulse (P0). The instantaneous ultrasonic frequency (f jm ) of the j-th ultrasound pulse (P j ) of the j-th ultrasonic period is used in this document as the inverse of the j-th ultrasonic period duration (T j ) of the j-th ultrasound period. ƒj=1Tj

[0087] In Fig. 2b is the corresponding time course of the ultrasonic burst instantaneous frequency (f m) against time (t) over the burst duration (bd) is plotted as an example. In the example of the Fig. 2b, the ultrasonic burst instantaneous frequency (f m ) jumps up. In the example of the Fig. 2a, the ultrasonic burst instantaneous frequency (f m ) is then preferably lowered continuously, at least temporarily, following a hyperbola until the end of the ultrasonic burst (UBE).

[0088] Fig. 2c shows an example of the frequency change rate (v f ) of the ultrasonic burst instantaneous frequency (f m ) over time (t) of the burst duration (bd). Initially, the frequency increases with a large positive rate of change (v f ) as a result of the ultrasonic burst start (UBS) from 0 Hz. The rate of frequency change (v f) is then briefly strongly negative in this example and then increases linearly in this example. The magnitude of the rate of change of frequency (v f ) decreases linearly in this example. Figure 3

[0089] Fig. 3 is used here to explain basic terminology for understanding terms used in this document. Fig. 3 shows an exemplary first spectral ultrasonic burst amplitude (A1) of a first ultrasonic transducer (US1) for the amplitude (A) of the sound radiation of this ultrasonic transducer (US1) when excited with a first excitation signal with the first excitation frequency (f A1 ). The exemplary first spectral ultrasonic burst amplitude (A1) has a first amplitude maximum (A max1) of the sound radiation of the first ultrasonic transducer (US1) at a first resonance frequency (f1) of the first ultrasonic transducer (US1). The exemplary first ultrasonic transducer (US1) has in the example of Fig. 3 a first bandwidth (Δf1) of the first spectral ultrasonic burst amplitude (A1) for the amplitude (A) of the sound emission of a first ultrasonic transducer (US1). In this document, this first bandwidth (Δf1) of a first spectral ultrasonic burst amplitude (A1) for the amplitude (A) of the first sound emission of a first ultrasonic transducer (US1) is defined here such that this first bandwidth (Δf1) of the first ultrasonic sensor (US1) represents the first upper half-maximum amplitude frequency (f 1o ), at which the amplitude (A) of the sound radiation of the first ultrasonic transducer (US1) is half of the first amplitude maximum (A max1) of the sound radiation of the first ultrasonic transducer (US1) at its first resonance frequency (f1), minus the first lower half-maximum amplitude frequency (f 1u ), at which the amplitude (A) of the sound radiation of the first ultrasonic transducer (US1) is also half of the first amplitude maximum (A max1 ) of the sound radiation of the first ultrasonic transducer (US1) at its first resonance frequency (f1). Figure 4

[0090] Fig. 4 is used here to explain basic terminology for understanding terms used in this document. Fig. 4 shows an exemplary second spectral ultrasonic burst amplitude (A2) for the amplitude (A) of the sound radiation of a second ultrasonic transducer (US2) when excited with a second excitation signal (AS2) with the second excitation frequency (f A2). The exemplary second spectral ultrasonic burst amplitude (A2) has a second amplitude maximum (A max2 ) of the sound radiation of the second ultrasonic transducer (US2) at a second resonance frequency (f2) of the second ultrasonic transducer (US2). The exemplary second ultrasonic transducer (US2) has in the example of Fig. 4 a second bandwidth (Δf2) of the second spectral ultrasonic burst amplitude (A2) for the amplitude (A) of the sound emission of a second ultrasonic transducer (US2). In this document, this second bandwidth (Δf2) of a second amplitude spectrum (A2) for the amplitude (A) of the second sound emission of a second ultrasonic transducer (US2) is defined here such that this second bandwidth (Δf2) of the second ultrasonic sensor (US2) represents the second upper half-maximum amplitude frequency (f 2o), at which the amplitude (A) of the sound radiation of the second ultrasonic transducer (US2) is half of the second amplitude maximum (A max2 ) of the sound radiation of the second ultrasonic transducer (US2) at its second resonance frequency (f2), minus the second lower half-maximum amplitude frequency (f 2u ), at which the amplitude (A) of the sound radiation of the second ultrasonic transducer (US2) is also half of the second amplitude maximum (A max2 ) of the sound radiation of the second ultrasonic transducer (US2) at its second resonance frequency (f2). Figure 5

[0091] Fig. 5 is also used here to explain basic terminology for understanding terms used in this document. Fig. Figure 5 shows an exemplary third spectral ultrasonic burst amplitude (A3) for the amplitude (A) of the sound radiation of a third ultrasonic transducer (US3) when excited with a transmission signal of the third excitation frequency (f A3 ). The exemplary third spectral ultrasonic burst amplitude (A3) has a third amplitude maximum (A max3 ) of the sound radiation of the third ultrasonic transducer (US3) at a third resonance frequency (f3) of the third ultrasonic transducer (US3). The exemplary third ultrasonic transducer (US3) has in the example of Fig. 5 a third bandwidth (Δf3) of the third spectral ultrasonic burst amplitude (A3) for the amplitude (A) of the sound emission of a third ultrasonic transducer (US3). In this document, this third bandwidth (Δf3) of a third spectral ultrasonic burst amplitude (A3) for the amplitude (A) of the third sound emission of a third ultrasonic transducer (US3) is defined here such that this third bandwidth (Δf3) of the third ultrasonic sensor (US3) represents the third upper half-maximum amplitude frequency (f 3o ), at which the amplitude (A) of the sound radiation of the third ultrasonic transducer (US3) is half of the third amplitude maximum (A max3 ) of the sound radiation of the third ultrasonic transducer (US3) at its third resonance frequency (f3), minus the third lower half-maximum amplitude frequency (f 3u), at which the amplitude (A) of the sound radiation of the third ultrasonic transducer (US3) is also half of the third amplitude maximum (A max3 ) of the sound radiation of the third ultrasonic transducer (US3) at its third resonance frequency (f3). Figure 6

[0092] Fig. 6 shows, by way of example, in two extreme configurations, the superposition of a first amplitude spectrum in the form of a first spectral ultrasonic burst amplitude (A1) of a first ultrasonic transducer (US1) and a second amplitude spectrum in the form of a second spectral ultrasonic burst amplitude (A2) of a second ultrasonic transducer (US2) and a third amplitude spectrum in the form of a third spectral ultrasonic burst amplitude (A3) of a third ultrasonic transducer (US3). Figure 6a

[0093] In the Fig. 6a is the frequency spacing (Δf 12) between the first resonance frequency (f1) of the first ultrasonic transducer (US1) and the second resonance frequency (f2) of the second ultrasonic transducer (US12) is smaller than the first bandwidth (Δf1) of the first ultrasonic transducer (US1).

[0094] In addition, the frequency spacing (Δf 12 ) between the first resonance frequency (f1) of the first ultrasonic transducer (US1) and the second resonance frequency (f2) of the second ultrasonic transducer (US12) is smaller than the second bandwidth (Δf2) of the second ultrasonic transducer (US2).

[0095] Furthermore, the frequency spacing (Δf 12 ) between the first resonance frequency (f1) of the first ultrasonic transducer (US1) and the second resonance frequency (f2) of the second ultrasonic transducer (US2) is less than half the sum of the first bandwidth (Δf1) of the first ultrasonic transducer (US1) and the second bandwidth (Δf2) of the second ultrasonic transducer (US2)

[0096] In the Fig. 6a is also the frequency spacing (Δf 23 ) between the second resonance frequency (f2) of the second ultrasonic transducer (US2) and the third resonance frequency (f3) of the third ultrasonic transducer (US3) is smaller than the second bandwidth (Δf2) of the second ultrasonic transducer (US2).

[0097] In addition, the frequency spacing (Δf 23 ) between the second resonance frequency (f2) of the second ultrasonic transducer (US2) and the third resonance frequency (f3) of the third ultrasonic transducer (US3) is smaller than the third bandwidth (Δf3) of the third ultrasonic transducer (US3).

[0098] Furthermore, the frequency spacing (Δf 23) between the second resonance frequency (f2) of the second ultrasonic transducer (US2) and the third resonance frequency (f3) of the third ultrasonic transducer (US3) is less than half the sum of the second bandwidth (Δf2) of the second ultrasonic transducer (US2) and the third bandwidth (Δf3) of the third ultrasonic transducer (US3).

[0099] In the example of Fig. 6a, moreover, the first bandwidth (Δf1) of the first ultrasonic transducer (US1) is approximately equal to the second bandwidth (Δf2) of the second ultrasonic transducer (US2) and the third bandwidth (Δf3) of the third ultrasonic transducer (US3).

[0100] In the example of Fig. 6a is the frequency spacing (Δf 12 ) between the first resonance frequency (f1) of the first ultrasonic transducer (US1) and the second resonance frequency (f2) of the second ultrasonic transducer (US2) is approximately equal to the frequency separation (Δf 23) between the second resonance frequency (f2) of the second ultrasonic transducer (US2) and the third resonance frequency (f3) of the third ultrasonic transducer (US3).

[0101] The advantage of selecting the parameters of the different ultrasonic transducers lies in the possible combination of the three ultrasonic transducers (US1, US2, US3) shown here as examples into a single ultrasonic transducer system with increased bandwidth. Instead of the ultrasonic transducers, ultrasonic transmitters can be used to transmit ultrasonic bursts and ultrasonic receivers can be used to receive them. This means that the transmitting function can be separated from the receiving function. If ultrasonic receivers are used instead of the ultrasonic transducers, the receiving bandwidth of the entire system is also expanded accordingly, which offers many advantages.

[0102] For example, it is possible to transmit an ultrasonic burst as an ultrasonic signal through such an ultrasonic sensor system (USS) whose required frequency bandwidth exceeds the total frequency bandwidth (Δf g ) of the ultrasonic sensor system (USS) with multiple ultrasonic transducers (US1, US2, US3). In this example, the Fig. 6a the exemplary total frequency bandwidth (Δf g ) of the ultrasonic sensor system (USS) comprising the first ultrasonic transducer (US1) and the second ultrasonic transducer (US2) and the third ultrasonic transducer (US3) is greater than the first bandwidth (Δf1) of the first ultrasonic transducer (US1) and greater than the second bandwidth (Δf2) of the second ultrasonic transducer (US2) and greater than the third bandwidth (Δf3) of the third ultrasonic transducer (US3).

[0103] This makes it possible for a first ultrasonic transducer to emit more than 50% of the sound energy at a first frequency at a first time during the transmission of an ultrasonic burst, and for a second ultrasonic transducer to emit less than 50% of the sound energy at this first frequency, while at a second time during the transmission of the ultrasonic burst, the first ultrasonic transducer to emit less than 50% of the sound energy at a second frequency, and for the second ultrasonic transducer to emit more than 50% of the sound energy at this second frequency. The first time and the second time are separated in time, and the first frequency is different from the second frequency.

[0104] Conversely, in the case of a receiving operation of the ultrasound transducers, it is possible that at a first point in time during the reception of a reflected ultrasound burst, a first of the ultrasound transducers (US1) receives more than 50% of the received amplitude at a first frequency and a second of the ultrasound transducers (US2) receives less than 50% of the received amplitude at this first frequency, while at a second point in time during the reception of the reflected ultrasound burst, the first of the ultrasound transducers (US1) receives less than 50% of the received amplitude at a second frequency and the second of the ultrasound transducers (US2) receives more than 50% of the received amplitude at this second frequency. The first point in time and the second point in time are spaced apart in time from one another, and the first frequency is different from the second frequency.

[0105] This enables the transmission of ultrasonic bursts with more complex coding and a wider frequency bandwidth, which significantly increases the signal-to-noise ratio and thus the range. It also enables the detection of better-resolved reflection signals from the ultrasonic burst. Figure 6b

[0106] In the Fig. 6b is the frequency spacing (Δf 12 ) between the first resonance frequency (f1) of the first ultrasonic transducer (US1) and the second resonance frequency (f2) of the second ultrasonic transducer (US2) is greater than the first bandwidth (Δf1) of the first ultrasonic transducer (US1).

[0107] In addition, the frequency spacing (Δf 12 ) between the first resonance frequency (f1) of the first ultrasonic transducer (US1) and the second resonance frequency (f2) of the second ultrasonic transducer (US2) is greater than the second bandwidth (Δf2) of the second ultrasonic transducer (US2).

[0108] Furthermore, the frequency spacing (Δf 12 ) between the first resonance frequency (f1) of the first ultrasonic transducer (US1) and the second resonance frequency (f2) of the second ultrasonic transducer (US2) is greater than half the sum of the first bandwidth (Δf1) of the first ultrasonic transducer (US1) and the second bandwidth (Δf2) of the second ultrasonic transducer (US2)

[0109] In the Fig. 6b is also the frequency spacing (Δf 23 ) between the second resonance frequency (f2) of the second ultrasonic transducer (US2) and the third resonance frequency (f3) of the third ultrasonic transducer (US3) is greater than the second bandwidth (Δf2) of the second ultrasonic transducer (US2).

[0110] In addition, the frequency spacing (Δf 23) between the second resonance frequency (f2) of the second ultrasonic transducer (US2) and the third resonance frequency (f3) of the third ultrasonic transducer (US3) is greater than the third bandwidth (Δf3) of the third ultrasonic transducer (US3).

[0111] Furthermore, the frequency spacing (Δf 23 ) between the second resonance frequency (f2) of the second ultrasonic transducer (US2) and the third resonance frequency (f3) of the third ultrasonic transducer (US3) is greater than half the sum of the second bandwidth (Δf2) of the second ultrasonic transducer (US2) and the third bandwidth (Δf3) of the third ultrasonic transducer (US3).

[0112] In the example of Fig. 6b, moreover, the first bandwidth (Δf1) of the first ultrasonic transducer (US1) is approximately equal to the second bandwidth (Δf2) of the second ultrasonic transducer (US2) and the third bandwidth (Δf3) of the third ultrasonic transducer (US3).

[0113] In the example of Fig. 6b is the frequency spacing (Δf 12 ) between the first resonance frequency (f1) of the first ultrasonic transducer (US1) and the second resonance frequency (f2) of the second ultrasonic transducer (US2) is approximately equal to the frequency separation (Δf 23 ) between the second resonance frequency (f2) of the second ultrasonic transducer (US2) and the third resonance frequency (f3) of the third ultrasonic transducer (US3).

[0114] When selecting the parameters of the ultrasound transducers (US1, US2, US3) according to the Fig. 6b, more complex signals can also be transmitted. However, a continuous frequency sweep (chirp) is no longer possible, as significant amplitude drops occur when the common excitation frequency (f A) of the ultrasonic transducers (US, US2, US3) lies in a frequency range between the amplitude spectra, here the three exemplary spectral ultrasonic burst amplitudes (A1, A2, A3) of the exemplary three ultrasonic transducers (US1, US2, US3). The corresponding amplitude dips of the Fig. 6a are considerably lower.

[0115] Basically, two basic operating modes are possible for such an ultrasonic sensor system: a) In the first operating mode, all ultrasonic transducers (US1, US2, US3) are controlled with the same control signal (AS) and thus with the same control instantaneous frequency (f A ) and controlled in phase synchronism. If the common control instantaneous frequency (f A ) within the total frequency bandwidth (Δf g ) of the ultrasonic sensor system (USS), at least one of the ultrasonic transmitters (US1, US2, US3) oscillates. b) In the second operating mode, at least one of the ultrasonic transducers (US1, US2, US3) is controlled with a different control signal (AS1, AS2, AS3) and thus typically no longer with the same control instantaneous frequency (f A ), but with a different control instantaneous frequency (f A1 , f A2 , f A3 ) and not phase-synchronized. Figures 7 to 10

[0116] The Fig. Figures 7 to 10 show possible types of frequency sweeps. In a frequency sweep, one or more ultrasonic transducers (US1, US2, US2) are controlled with a control signal (AS) in which the control instantaneous frequency (f A ) is a function of time and changes during the transmission of an ultrasonic burst (UB) by this ultrasonic transducer. In the examples of Fig. 7 to 10 show various possible ultrasonic sweeps with a non-linear course of the ultrasonic burst instantaneous frequency (f m ). The ultrasonic burst instantaneous frequency (f m ) is related to the instantaneous control frequency (f A ) of the control signal (AS) of the ultrasonic transducers (US1, US2, US3) and typically follows this. In the examples of the Fig. 7 to 10, only a first ultrasonic transducer (US1) of the ultrasonic transducers (US1, US2, US3) is used for the transmission of the ultrasonic burst (UB).

[0117] Fig. Figure 7b shows the curve of the first spectral ultrasonic burst amplitude (A1) of the first ultrasonic transducer (US1) as a function of the instantaneous control frequency (f A ) in vertical direction corresponding to the Fig. 7a.

[0118] Fig. Figure 7a shows the first frequency response (SF1) of the ultrasonic burst instantaneous frequency (f m ) of a first ultrasonic partial burst of the control signal for generating an ultrasonic burst (UB) by means of the first ultrasonic transducer (US1). The first ultrasonic transducer (US1) has a first upper half-maximum amplitude frequency (f 1o ) and a first lower half-maximum amplitude frequency (f 1u ). At a first transmission start time (t 1s ) begins in the example of Fig. 7a the first ultrasonic transducer (US1) with an ultrasonic burst instantaneous frequency (f m ) corresponding to a first starting frequency (f 1s ) and to emit sound. For this purpose, the first ultrasonic transmitter (US1) is typically provided with a control signal (AS) with a corresponding instantaneous first start control frequency [f A1s ] is triggered. At a first half-frequency time (t 1 / 50%), the first ultrasonic transducer (US1) transmits at a first half frequency (f 1 / 50% ). For this purpose, the first ultrasonic transducer (US1) is typically supplied with a control signal having a corresponding instantaneous first half-frequency control frequency [f A1 / 50% ] is triggered. At a first transmission end time (t 1e ) stops in the example of Fig. 7a the first ultrasonic transducer (US1) starts the transmission process with a first final frequency (f 1e ). For this purpose, typically at this first transmission end time (t 1e ) the first ultrasonic transmitter (US1) with a control signal with a corresponding instantaneous first final control frequency [f A1e ] is controlled.

[0119] The first half-frequency control frequency [f A1 / 50% ] is calculated for the purposes of this document as follows: ƒA1 / 50%=ƒ1s−ƒ1e2+ƒ1e

[0120] The first starting frequency (f 1s) lies naturally between the first upper half-maximum amplitude frequency (f 1o ) and the first lower half-maximum amplitude frequency (f 1u ).

[0121] The first half frequency (f 1 / 50% ) lies equally between the first upper half-maximum amplitude frequency (f 1o ) and the first lower half-maximum amplitude frequency (f 1u ).

[0122] The first final frequency (f 1e ) also lies between the first upper half-maximum amplitude frequency (f 1o ) and the first lower half-maximum amplitude frequency (f 1u ).

[0123] The ultrasonic burst duration (bd) is obtained in the example of Fig. 7 as the time difference between the first transmission end time (t 1e ) minus the first transmission start time (t 1s ). bd=t1e−t1s

[0124] The half-frequency time (t 1 / 50%), at which the control signal of the first ultrasonic transducer (US1) reaches the half-frequency control frequency [f A1 / 50% ] or at which the transmission frequency of the sound radiation of the first ultrasonic transducer (US1) reaches the first half frequency (f 1 / 50% ), divides the burst duration (bd) into a first temporal burst phase (t 1a ) and an immediately following second temporal burst phase (t 1b ). It is suggested that the first burst phase (t 1a ) differ considerably in length compared to the second burst phase (t 1b ). This divides the burst duration (bd) into two temporally unequal burst phases (t 1a , t 1b ). Furthermore, it is proposed that the frequency response of the ultrasonic burst instantaneous frequency (f m) is monotonous, preferably even strictly monotonous, either decreasing or increasing. The initial and final phase of the sound emission for switching on and off the first ultrasonic transducer (US1) used here as an example is not taken into account in this monotonicity condition for the sake of simplicity, since the switching on process is naturally always increasing (increasing from 0 Hz) and the switching off process is always decreasing (falling to 0 Hz). In the example of the Fig. 7a is the frequency response (SF1) of the ultrasonic burst instantaneous frequency (f m ) of a first ultrasonic subburst is strictly monotonically decreasing and the first temporal burst phase (t 1a ) is considerably shorter in time than the second burst phase (t 1b ). Figure 8

[0125] Fig. 8b corresponds to the Fig. 7b. Reference is made to the relevant description.

[0126] Fig. 8a corresponds to the Fig. 7a with the difference that the frequency response (SF1) of the ultrasonic burst instantaneous frequency (f m ) of a first ultrasonic subburst within an ultrasonic burst (UB) is, for example, strictly monotonically increasing and the first temporal burst phase (t 1a ) is considerably shorter in time than the second burst phase (t 1b ) is. Figure 9

[0127] Fig. 9b corresponds to the Fig. 7b. Reference is made to the relevant description.

[0128] Fig. 9a corresponds to the Fig. 7a with the difference that the frequency response (SF1) of the ultrasonic burst instantaneous frequency (f m ) of a first ultrasonic subburst within an ultrasonic burst (UB) is, for example, strictly monotonically increasing and the first temporal burst phase (t 1a ) is considerably longer than the second burst phase (t 1b ) is. Figure 10

[0129] Fig. 10b corresponds to the Fig. 7b. Reference is made to the relevant description.

[0130] Fig. 10a corresponds to the Fig. 7a with the difference that the frequency response (SF1) of the ultrasonic burst instantaneous frequency (f m ) of a first ultrasonic subburst within an ultrasonic burst (UB) is, for example, strictly monotonically decreasing and the first temporal burst phase (t 1a ) is considerably longer than the second burst phase (t 1b ) is. Figure 11

[0131] Fig. 11 shows an exemplary arrangement consisting of a first ultrasonic transducer (US1) and a second ultrasonic transducer (US2) and a third ultrasonic transducer (US3). In the example of Fig. 11, the ultrasonic transducers (US1, US2, US3) are arranged in an isosceles triangle, the edge length of which is less than twice the diameter of the sound radiation surfaces of the ultrasonic transducers (US1, US2, US3). In the example of the Fig. 11, the sound radiation surfaces are circular and, for example, the same size for all three ultrasonic transducers (US1, US2, US3). The first ultrasonic transducer (US1), when transmitting, transmits at a first ultrasonic burst instantaneous frequency (f 1m ). The second ultrasonic transducer (US2), when transmitting, transmits at a second ultrasonic burst instantaneous frequency (f 2m ). The third ultrasonic transducer (US3), when transmitting, transmits at a third ultrasonic burst instantaneous frequency (f 3m ).

[0132] Preferably, the ultrasonic transducers (US1, US2, US3) are arranged in an isosceles triangle, the edge lengths of which are less than ten times the diameter of the sound radiating surfaces of the ultrasonic transducers (US1, US2, US3) and / or less than five times the diameter of the sound radiating surfaces of the ultrasonic transducers (US1, US2, US3) and / or less than three times the diameter of the sound radiating surfaces of the ultrasonic transducers (US1, US2, US3) and / or better less than twice the diameter of the sound radiating surfaces of the ultrasonic transducers (US1, US2, US3). Figure 12

[0133] Fig. 12 corresponds to the Fig. 7 with the difference that now a frequency sweep is generated using three ultrasonic sensors (US1, US2, US3).

[0134] In the example of Fig. 12, all three ultrasonic transducers (US1, US2, US3) are to be controlled with the same control signal and the same instantaneous control frequency (f A ) and therefore with the same ultrasonic burst instantaneous frequency (f 1m , f 2m , f 3m ) emit sound. In this example, the Fig. 12 in contrast to Fig. 11 all three exemplary ultrasonic transducers (US1, US2, US3) with a respective ultrasonic burst instantaneous frequency (f 1m , f 2m , f 3m ) according to the current control frequency (f A ) or not or only negligible if the instantaneous control frequency (f A ) is just outside their respective bandwidth (Δf1, Δf2, Δf3) of the respective ultrasonic transducer (US1, US2, US3).

[0135] The first ultrasonic transducer (US1) has a first spectral ultrasonic burst amplitude (A1) of the first ultrasonic transducer (US1).

[0136] The second ultrasonic transducer (US2) has a second spectral ultrasonic burst amplitude (A2) of the second ultrasonic transducer (US2).

[0137] The third ultrasound transducer (US3) has a third spectral ultrasound burst amplitude (A3) of the third ultrasound transducer (US3).

[0138] These spectral ultrasonic burst amplitudes (A1, A2, A3) are intended to exemplify the situation of the exemplary Fig. 6a. The corresponding description of the Fig. 6a is expressly referred to here.

[0139] In contrast to the transmission of the ultrasonic burst (UB) according to the Fig. 7a, ultrasonic burst instantaneous frequencies (f m) are emitted which are outside the first bandwidth (Δf1) of the first ultrasonic transducer (US1). This means that the frequency bandwidth of the Fig. 12 emitted ultrasonic bursts (UB) is considerably wider than the frequency bandwidth of the Fig. 7a emitted ultrasonic bursts (UB).

[0140] It is important here that the first bandwidth (Δf1) of the first ultrasonic transducer (US1) overlaps with the second bandwidth (Δf2) of the second ultrasonic transducer (US2) and that the second bandwidth (Δf2) of the second ultrasonic transducer (US2) overlaps with the third bandwidth (Δf3) of the third ultrasonic transducer (US3).

[0141] This makes it possible for the first frequency response (SF1) of the ultrasonic burst instantaneous frequency (f m) within the ultrasonic burst (UB) when transmitted by means of the first ultrasonic transducer (US1) and the second ultrasonic transducer (US2) and the third ultrasonic transducer (US3) of any curve within the total frequency bandwidth (Δf g ) of the ultrasonic sensor system (USS). In this respect, the Fig. 12 is only one particularly preferred course of many courses that become possible.

[0142] At a third transmission start time (t 3s ) begins in the example of Fig. 12 the third ultrasonic transducer (US3) with the transmission of an ultrasonic partial burst with a third starting frequency (f 3s ), which corresponds to a third excitation start frequency [f A3s] for the frequency of the three ultrasonic transducers (US1, US2, US3) in the example of Fig. 12 jointly controlling excitation signals. The third ultrasonic transducer (US3) then emits the ultrasonic burst with an instantaneous ultrasonic burst frequency (f m ) that were available at this transmission start time (t 3s ) of the third starting frequency (f 3s ). The third starting frequency (f 3s ) is necessarily within the third bandwidth (Δf3) of the third ultrasonic transducer (US3). In the example of the Fig. 12 is the third starting frequency (f 3s) outside the second bandwidth (Δf2) of the second ultrasonic transducer (US2) and outside the first bandwidth (Δf1) of the first ultrasonic transducer (US1). Therefore, for the duration of a third single-mode time (smt3), only the third ultrasonic transducer (US3) transmits. During this period of a third single-mode time (smt3), a significant excitation of the first ultrasonic transducer (US1) and the second ultrasonic transducer (US2) with the instantaneous excitation frequency (f A ) using the control signal (AS) is not possible.

[0143] The control device (AV) of the three ultrasonic transducers (US1, US2, US3) lowers in the example of Fig. 12 now the current control frequency (f A ) continuously within the third single-mode time (smt3). At a second transmission start time (t 2s ) begins in the example of Fig. 12 the second ultrasonic transducer (US2) also in a fixed phase relationship to the transmission of the third ultrasonic transducer (US3) with the transmission of an ultrasonic signal at a second starting frequency (f 2s ), which corresponds to a second excitation start frequency [f A2s ] for the frequency of the three ultrasonic transducers (US1, US2, US3) in the example of Fig. 12 jointly controlling excitation signal. The third ultrasonic transducer (US3) and the second ultrasonic transducer (US2) radiate from this second transmission start time (t 2s ) phase-synchronous with the same ultrasonic burst instantaneous frequency (f m ) in this example. This starts the first dual-mode time (dmt 23 ), in which the third ultrasonic transducer (US3) and the second ultrasonic transducer (US2) emit sound simultaneously.

[0144] The control device (AV) of the three ultrasonic transducers (US1, US2, US3) lowers in the example of Fig. 12 now the current control frequency (f A ) within the dual-mode time (dmt 23 ), in which the third ultrasonic transducer (US3) and the second ultrasonic transducer (US2) emit sound, continues to decrease continuously. This also causes the instantaneous ultrasonic burst frequency (f m ) with which the third ultrasonic transducer (US3) and the second ultrasonic transducer (US2) continue to emit sound. At a third transmission end time (t 3e ) stops in the example of Fig. 12 the third ultrasonic transducer (US3) transmits its ultrasonic signal at a third final frequency (f 3e ), which corresponds to a third excitation end frequency [f A3e ] for the frequency of the three ultrasonic transducers (US1, US2, US3) in the example of Fig. 12 jointly controlling excitation signal (AS). In this example, this is where the Fig. 12 a second single-mode time (smt2) in which only the second ultrasonic transducer (US2) emits sound.

[0145] The control device (AV) of the three ultrasonic transducers (US1, US2, US3) lowers in the example of Fig. 12 now the current control frequency (f A ) continues to decrease continuously within the second single-mode time (smt2). This also causes the instantaneous ultrasonic burst frequency (f m ), with which the second ultrasonic transducer (US2) emits sound. At a first transmission start time (t 1s ) begins in the example of Fig. 12 the first ultrasonic transducer (US1) also in a fixed phase relationship to the transmission of the second ultrasonic transducer (US2) with the transmission of an ultrasonic signal at a first starting frequency (f 1s) corresponding to a first excitation start frequency [f A1s ] for the frequency of the three ultrasonic transducers (US1, US2, US3) in the example of Fig. 12 jointly controlling excitation signals. The first ultrasonic transducer (US1) and the second ultrasonic transducer (US2) radiate from this first transmission start time (t 1s ) phase-synchronous with the same ultrasonic burst instantaneous frequency (f m ) in this example. This starts a second dual-mode time (dmt 12 ), in which the first ultrasonic transducer (US1) and the second ultrasonic transducer (US2) emit sound.

[0146] The control device of the three ultrasonic transducers (US1, US2, US3) lowers in the example of the Fig. 12 now the current control frequency (f A ) within the dual-mode time (dmt 12), in which the first ultrasonic transducer (US1) and the second ultrasonic transducer (US2) emit sound, continues to decrease continuously. This also causes the instantaneous ultrasonic burst frequency (f m ), with which the second ultrasonic transducer (US2) and the first ultrasonic transducer (US1) continue to radiate sound.

[0147] At a second transmission end time (t 2e ) stops in the example of Fig. 12 the second ultrasonic transducer (US2) transmits an ultrasonic signal at a second final frequency (f 2e ) corresponding to a second excitation end frequency [f A2e ] for the frequency of the three ultrasonic transducers (US1, US2, US3) in the example of Fig. 12 jointly controlling excitation signal. This means that at this time the first ultrasonic transducer (US1) and the second ultrasonic transducer (US2) are operating at an instantaneous ultrasonic burst frequency (f m) emit sound corresponding to this second wide end frequency (f 2e ). In this example, this is how the Fig. 12 a first single-mode time (smt1) in which only the first ultrasonic transducer (US1) emits sound.

[0148] The control device of the three ultrasonic transducers (US1, US2, US3) lowers in the example of the Fig. 12 now the current control frequency (f A ) continues to decrease continuously during the first single-mode time (smt1), in which only the first ultrasonic transducer (US1) emits sound. This also causes the instantaneous ultrasonic burst frequency (f m ) with which the remaining first ultrasonic transducer (US1) still emits sound. At a first end of transmission time (t 1e ) stops in the example of Fig. 12 the first ultrasonic transducer (US1) transmits an ultrasonic signal at a first final frequency (f 1e ) corresponding to a first excitation end frequency [fA1e ] for the frequency of the three ultrasonic transducers (US1, US2, US3) in the example of Fig. 12 jointly controlling excitation signal. This means that at this time the first ultrasonic transducer (US1) with an ultrasonic burst instantaneous frequency (f m ) emits sound corresponding to this second wide end frequency (f 2e ). This ends the Fig. 12 the emission of the ultrasonic burst (US) and thus the burst duration (bd) is interrupted. The sound emission then ceases altogether, and the ultrasonic burst (UB) is terminated. Figure 13

[0149] Fig. 13 shows a simplified and schematic illustration of an exemplary system for generating the exemplary frequency response of the Fig. 12. For example, an ultrasonic sensor system (USS) is used according to Fig. 11. A control device (AV) can be part of the ultrasonic sensor system (USS) or can be arranged outside the ultrasonic sensor system (USS).

[0150] The control device (AV) generates one or more control signals (AS), which are, for example, fed in parallel to a plurality of ultrasonic transducers (US1, US2, US3). Thus, the ultrasonic transducers (US1, US2, US3) of the plurality of ultrasonic transducers (US1, US2, US3) are driven at the same control frequency (f A ) of the control signal (AS). However, the ultrasonic transducers (US1, US2, US3) only oscillate when the current control frequency (f A ) of the control signal (AS) lies within their respective bandwidth (Δf1, Δf2, Δf3). Figure 14

[0151] Fig. 14 corresponds in essential parts to the Fig. 12. However, the excitation signal (AS) temporarily comprises more than one excitation frequency (fA ). For example, the control signal (AS) can have a first excitation frequency (f A1 ) of a first excitation signal component and a second excitation frequency (f A2 ) of a second excitation signal component and a third excitation frequency (f A3 ) of a third excitation signal component. The first excitation signal component and the second excitation signal component and the third excitation signal component are then preferably superimposed by summation to form the actual excitation signal (AS).

[0152] In the example of Fig. 14, in a first phase of the exemplary ultrasonic burst (UB), all three ultrasonic transducers (US1, US2, US3) are to be controlled with the same control signal (AS) with the same first control instantaneous frequency (f A1 ) are controlled. In this example, the Fig. 14 in contrast to Fig. 11 all three exemplary ultrasonic transducers (US1, US2, US3) again with the frequencies corresponding to the control instantaneous frequencies (f A1 ,f A2 ) or not or only negligible if the control instantaneous frequencies (f A1 ,f A2 ) are just outside their respective bandwidths (Δf1, Δf2, Δf3).

[0153] The first ultrasound transducer (US1) has, as in Fig. 12 a first spectral ultrasonic burst amplitude (A1) of the first ultrasonic transducer (US1).

[0154] The second ultrasound transducer (US2) has the following characteristics: Fig. 12 a second spectral ultrasonic burst amplitude (A2) of the second ultrasonic transducer (US2).

[0155] The third ultrasound transducer (US3) has the following characteristics: Fig. 12 a third spectral ultrasonic burst amplitude (A3) of the third ultrasonic transducer (US3).

[0156] These spectral ultrasonic burst amplitudes (A1, A2, A3) should be used here as in Fig. 12 exemplary of the situation of the exemplary Fig. 6a. The corresponding description of the Fig. 6a is expressly referred to here.

[0157] In contrast to the transmission of the ultrasonic burst (UB) according to the Fig. 12 are now in the Fig. 14 temporarily more than two ultrasonic burst instantaneous frequencies within the emitted ultrasonic burst are emitted. This means that the frequency bandwidth of the Fig. 14 emitted ultrasonic bursts (UB) is also related to individual transmission times during the burst duration (bd) of the ultrasonic burst (UB) at least temporarily considerably wider than the current frequency bandwidth of the Fig. 12 emitted ultrasonic bursts (UB).

[0158] It is also important here that the first bandwidth (Δf1) of the first ultrasonic transducer (US1) overlaps with the second bandwidth (Δf2) of the second ultrasonic transducer (US2) and that the second bandwidth (Δf2) of the second ultrasonic transducer (US2) overlaps with the third bandwidth (Δf3) of the third ultrasonic transducer (US3).

[0159] This makes it possible for the first frequency response (SF1) of the first excitation frequency (f A1 ) a first signal component of the control signal (AS) for generating an ultrasonic burst (UB) by means of the first ultrasonic transducer (US1) and the second ultrasonic transducer (US2) and the third ultrasonic transducer (US3) as the first ultrasonic subburst within the ultrasonic burst (UB) and thus the first frequency response (SF1) of the instantaneous ultrasonic frequency (f m1 ) follows any curve within the thus enlarged overall bandwidth. In this respect, the Fig. 14 is only one particularly preferred course of many courses that become possible.

[0160] Furthermore, it is also possible that in addition to the first frequency response (SF1), a second frequency response (SF2) of a second ultrasonic burst instantaneous frequency (f m2 ) of a second ultrasonic subburst within an ultrasonic burst (UB) and, if applicable, a third frequency curve (SF3) of a third ultrasonic burst instantaneous frequency (f m3 ) of a third ultrasonic subburst within the ultrasonic burst (UB) of any second curve or third, not drawn curve within the thus enlarged total bandwidth, independent of the first frequency response (SF1) of the first ultrasonic instantaneous frequency (f m1 ) will follow. In this respect, the Fig. 14 is only one particularly preferred curve of many curves and frequency curve combinations that become possible in this way. Theoretically, n frequency curves, with n as a positive integer, n ultrasonic burst instantaneous frequencies of ultrasonic subbursts within the ultrasonic burst (UB) n arbitrary curves within the thus enlarged total bandwidth can be generated independently of the first frequency curve (SF1) of the first ultrasonic instantaneous frequency (f m1 ) (f A1 ) consequences

[0161] At a third transmission start time (t 3s ) begins in the example of Fig. 14 the third ultrasonic transducer (US3) with the transmission of an ultrasonic signal with a third starting frequency (f 3s ) as the first instantaneous ultrasonic frequency (f m1 ), which corresponds to a third excitation start frequency [f A3s ] for the first excitation frequency (f A1 ) of the three ultrasound transducers (US1, US2, US3) in the example of Fig. 14 jointly controlling excitation signal (AS). The third starting frequency (f 3s ) lies within the third bandwidth (Δf3) of the third ultrasonic transducer (US3). In the example of the Fig. 14 is the third starting frequency (f 3s ) outside the second bandwidth (Δf2) of the second ultrasonic transducer (US2) and outside the first bandwidth (Δf1) of the first ultrasonic transducer (US1). For the duration of a third single-mode time (smt3), only the third ultrasonic transducer (US3) transmits at the first instantaneous ultrasonic frequency (f m1 ). In this period of a third single-mode time (smt3), a significant excitation of the first ultrasonic transducer (US1) and the second ultrasonic transducer (US2) with the instantaneous first excitation frequency (f A1 ) not possible.

[0162] The control device (AS) of the three ultrasonic transducers (US1, US2, US3) lowers in the example of Fig. 13 now the current first control frequency (f A1 ) and thus the first instantaneous ultrasonic frequency (f m1 ) continuously within the third single-mode time (smt3). At a second transmission start time (t 2s ) begins in the example of Fig. 14 the second ultrasonic transducer (US2) also in a fixed phase relationship to the transmission of the third ultrasonic transducer (US3) with the transmission of an ultrasonic signal with the first ultrasonic instantaneous frequency (f m1 ) at a second starting frequency (f 2s ), which corresponds to a second excitation start frequency [f A2s ] for the current first control frequency (f A1 ) of the three ultrasound transducers (US1, US2, US3) in the example of Fig. 14 jointly controlled excitation signal (AS). This starts a dual-mode time (dmt23 ), in which the third ultrasonic transducer (US3) and the second ultrasonic transducer (US2) transmit sound with the first instantaneous ultrasonic frequency (f m1 ) radiate.

[0163] The control device (AS) of the three ultrasonic transducers (US1, US2, US3) lowers in the example of Fig. 14 now the first instantaneous control frequency (f A1 ) within the dual-mode time (dmt 23 ), in which the third ultrasonic transducer (US3) and the second ultrasonic transducer (US2) transmit sound with the first instantaneous ultrasonic frequency (f m1 ) continue to transmit continuously. At a third transmission end time (t 3e ) stops in the example of Fig. 14 the third ultrasonic transducer (US3) transmits an ultrasonic signal with the first instantaneous ultrasonic frequency (f m1 ) at a third final frequency (f 3e ), which corresponds to a third excitation end frequency [f A3e] for the current first control frequency (f A1 ) of the three ultrasound transducers (US1, US2, US3) in the example of Fig. 14 jointly controlling excitation signal (AS). In this example, this is where the Fig. 14 a second single-mode time (smt2) in which only the second ultrasonic transducer (US2) transmits sound with the first instantaneous ultrasonic frequency (f m1 ) radiates.

[0164] The control device (AS) of the three ultrasonic transducers (US1, US2, US3) lowers in the example of Fig. 14 now the current first control frequency (f A1 ) and thus the first instantaneous ultrasonic frequency (f m1 ) continues to decrease continuously within the second single-mode time (smt2). At a first transmission start time (t 1s ) begins in the example of Fig. 14 the first ultrasonic transducer (US1) also in a fixed phase relationship to the transmission of the second ultrasonic transducer (US2) with the transmission of an ultrasonic signal of the first ultrasonic instantaneous frequency (f m1 ) at a first starting frequency (f 1s ) corresponding to a first excitation start frequency [f A1s ] for the control frequency (f A1 ) of the three ultrasound transducers (US1, US2, US3) in the example of Fig. 14 jointly controlled excitation signal (AS). This starts a dual-mode time (dmt 12 ), in which the first ultrasonic transducer (US1) and the second ultrasonic transducer (US2) are operated at the first instantaneous ultrasonic frequency (f m1 ) emit sound.

[0165] The control device (AS) of the three ultrasonic transducers (US1, US2, US3) lowers in the example of Fig. 14 now the current first control frequency (f A1) and thus the first instantaneous ultrasonic frequency (f m1 ) within the dual-mode time (dmt 12 ), in which the first ultrasonic transducer (US1) and the second ultrasonic transducer (US2) transmit sound with the first instantaneous ultrasonic frequency (f m1 ) continue to transmit continuously. At a second transmission end time (t 2e ) stops in the example of Fig. 14 the second ultrasonic transducer (US2) transmits an ultrasonic signal with the first instantaneous ultrasonic frequency (f m1 ) at a second final frequency (f 2e ) corresponding to a second excitation end frequency [f A2e ] for the first control frequency (f A1 ) of the three ultrasound transducers (US1, US2, US3) in the example of Fig. 14 jointly controlling excitation signal (AS). In this example, this is where the Fig. 14 a first single-mode time (smt1) in which only the first ultrasonic transducer (US1) transmits sound with the first instantaneous ultrasonic frequency (f m1 ) radiates.

[0166] The control device of the three ultrasonic transducers (US1, US2, US3) lowers in the example of the Fig. 14 then the current first control frequency (f A1 ) and thus the first instantaneous ultrasonic frequency (f m1 ) within the first single-mode time (smt1), in which only the first ultrasonic transducer (US1) transmits sound with the first instantaneous ultrasonic frequency (f m1 ) continues to emit continuously. At a first end of transmission time (t 1e ) stops in the example of Fig. 14 the first ultrasonic transducer (US1) transmits the proportional ultrasonic signal with the first instantaneous ultrasonic frequency (f m1 ) at a first final frequency (f 1e ) corresponding to a first excitation end frequency [f A1e] for the current first control frequency (f A1 ) of the three ultrasound transducers (US1, US2, US3) in the example of Fig. 14 jointly controlling excitation signal. In this example, this ends the Fig. 12 the emission of the ultrasonic burst (US) and thus the burst duration (bd). The sound emission then ends.

[0167] In contrast to the Fig. 12 is now at least for a temporal portion of the burst duration (bd) parallel to the first ultrasonic subburst with the first frequency curve (SF1) of the first ultrasonic instantaneous frequency (f m1 ) a second ultrasonic burst component with a second frequency response (SF2) of the second instantaneous ultrasonic frequency (f m2 ) is preferably superimposed by summation in the control signal (AS). The control signal (AS) therefore typically has a first instantaneous ultrasonic frequency (f m1) as the first frequency component and a second instantaneous ultrasonic frequency (f m2 ) as frequency components.

[0168] In the example of Fig. 14 is exemplified in the first single-mode time (smt1) by generating this second frequency response (SF2) of the second ultrasonic burst instantaneous frequency (f m2 ) of a second ultrasonic subburst within an ultrasonic burst (UB) from the structure of the ultrasonic burst of the Fig. 12 deviated.

[0169] At a further third transmission start time (t 3sb ) begins in the example of Fig. 14 the third ultrasonic transducer (US3) with the transmission of an additional ultrasonic partial burst with the third starting frequency (f 3s ) as the second instantaneous ultrasonic frequency (f m2 ), which again corresponds to the third excitation start frequency [f A3s ] for the second excitation frequency (f A2) of the three ultrasound transducers (US1, US2, US3) in the example of Fig. 14 jointly controlling excitation signal (AS). From this point onwards, the third transmission start time (t 3sb ), the control signal (AS) therefore not only contains a first ultrasonic partial burst with a first ultrasonic instantaneous frequency (f m1 ), but also a second ultrasonic subburst with a second ultrasonic instantaneous frequency (f m2 ). The third starting frequency (f 3s ) is typically within the third bandwidth (Δf3) of the third ultrasonic transducer (US3), as before. It is assumed unchanged here. In the example of Fig. 14 is the third starting frequency (f 3s ) outside the second bandwidth (Δf2) of the second ultrasonic transducer (US2) and outside the first bandwidth (Δf1) of the first ultrasonic transducer (US1). For the duration of a third dual-mode time (dmt13 ) send in the example of the Fig. 14 the third ultrasound transducer (US3) with a second instantaneous ultrasound frequency (f m2 ) and the first ultrasonic transducer (US1) with a first instantaneous ultrasonic frequency (f m1 ) each emits a sound signal.

[0170] Since the first instantaneous control frequency (f A1 ) in this third dual-mode time (dmt 13 ) below the third lower half-maximum amplitude frequency (f 3u ), the third ultrasonic transducer (US3) does not oscillate at the first instantaneous control frequency (f A1 ).

[0171] Since the first instantaneous control frequency (f A1 ) in this third dual-mode time (dmt 13 ) also below the second lower half-maximum amplitude frequency (f 2u ), the second ultrasonic transducer (US2) also does not oscillate at the first instantaneous control frequency (f A1 ).

[0172] Since the second instantaneous control frequency (f A2 ) in this third dual-mode time (dmt 13 ) above the second upper half-maximum amplitude frequency (f 2o ), the second ultrasonic transducer (US2) does not oscillate at the second instantaneous control frequency (f A2 ).

[0173] Since the second instantaneous control frequency (f A2 ) in this third dual-mode time (dmt 13 ) above the first upper half-maximum amplitude frequency (f 1o ), the first ultrasonic transducer (US1) does not oscillate at the second instantaneous control frequency (f A2 ).

[0174] During this period of a third dual-mode time (dmt 13 ) is a significant excitation of the first ultrasonic transducer (US1) and the second ultrasonic transducer (US2) with the instantaneous second excitation frequency (f A2 ) not possible.

[0175] During this period, which corresponds to a third dual-mode time (dmt 13 ), a significant excitation of the third ultrasonic transducer (US3) and the second ultrasonic transducer (US2) with the instantaneous first excitation frequency (f A1 ) not possible.

[0176] The control device (AS) of the three ultrasonic transducers (US1, US2, US3) lowers in the example of Fig. 14 now the current first control frequency (f A1 ) and thus the first instantaneous ultrasonic frequency (f m1 ) and the current second control frequency (f A2 ) and thus the second instantaneous ultrasonic frequency (f m2 ) within the third dual-mode time (dmt 13 ) together continuously. At a further second transmission start time (t 2sb ) begins in the example of Fig. 14 the second ultrasonic transducer (US2) also in a fixed phase relationship to the transmission of the third ultrasonic transducer (US3) with the transmission of an ultrasonic signal with the second ultrasonic instantaneous frequency (f m2 ) at a second starting frequency (f 2s ), which corresponds to a second excitation start frequency [f A2s ] for the current second control frequency (f A2 ) of the second signal component of the three ultrasonic transducers (US1, US2, US3) in the example of Fig. 14 jointly controlled excitation signal (AS). This starts a tri-mode time (tmt 123 ), in which the third ultrasonic transducer (US3) is operated at the second instantaneous ultrasonic frequency (f m2 ) and the second ultrasonic transducer (US2) with the second instantaneous ultrasonic frequency (f m2 ) and the first ultrasonic transducer (US1) with the first instantaneous ultrasonic frequency (f m1 ) emit sound.

[0177] Since the first instantaneous control frequency (f A1 ) in this third dual-mode time (dmt 13 ) below the third lower half-maximum amplitude frequency (f 3u ), the third ultrasonic transducer (US3) does not oscillate at the first instantaneous control frequency (f A1 ).

[0178] Since the first instantaneous control frequency (f A1 ) in this third dual-mode time (dmt 13 ) also below the second lower half-maximum amplitude frequency (f 2u ), the second ultrasonic transducer (US2) also does not oscillate at the first instantaneous control frequency (f A1 ).

[0179] Since the second instantaneous control frequency (f A2 ) in this third dual-mode time (dmt 13 ) now below the second upper half-maximum amplitude frequency (f 2o ) and above the second lower half-maximum amplitude frequency (f 2u), the second ultrasonic transducer (US2) now oscillates at the second instantaneous control frequency (f A2 ) and emits sound with the second instantaneous ultrasonic frequency (f m2 ).

[0180] Since the second instantaneous control frequency (f A2 ) in this third dual-mode time (dmt 13 ) above the first upper half-maximum amplitude frequency (f 1o ), the first ultrasonic transducer (US1) does not oscillate at the second instantaneous control frequency (f A2 ) and emits sound of the first instantaneous ultrasonic frequency (f m1 ).

[0181] During this period of a third tri-mode time (tmt 123 ) is a significant excitation of the first ultrasonic transducer (US1) with the instantaneous second excitation frequency (f A2 ) not possible.

[0182] During this period of a third tri-mode time (tmt 123) is a significant excitation of the third ultrasonic transducer (US3) and the second ultrasonic transducer (US2) with the instantaneous first excitation frequency (f A1 ) not possible.

[0183] The control device (AS) of the three ultrasonic transducers (US1, US2, US3) lowers in the example of Fig. 14 now the first instantaneous control frequency (f A1 ) and the second instantaneous control frequency (f A2 ) and thus the first instantaneous ultrasonic frequency (f m1 ) and the second instantaneous ultrasonic frequency (f m2 ) within the tri-mode time (tmt 123 ), in which the third ultrasonic transducer (US3) and the second ultrasonic transducer (US2) and the first ultrasonic transducer (US1) emit sound, continues to emit sound. At a further third transmission end time (t 3eb ) stops in the example of Fig. 14 the third ultrasonic transducer (US3) transmits the ultrasonic signal with the second instantaneous ultrasonic frequency (f m2 ) at a third final frequency (f 3e ), which corresponds to a third excitation end frequency [f A3e ] for the current second control frequency (f A2 ) of the signal component of the three ultrasonic transducers (US1, US2, US3) in the example of Fig. 14 jointly controlling excitation signal (AS). In this example, this is where the Fig. 14 a fourth dual-mode time (dmt 12b ) in which only the second ultrasonic transducer (US2) with the second instantaneous ultrasonic frequency (f m2 ) and the first ultrasonic transducer (US1) with the first instantaneous ultrasonic frequency (f m1 ) emit sound.

[0184] The control device (AS) of the three ultrasonic transducers (US1, US2, US3) lowers in the example of Fig. 14 now the current first control frequency (f A1) and the current second control frequency (f A2 ) and thus the first instantaneous ultrasonic frequency (f m1 ) and the second instantaneous ultrasonic frequency (f m2 ) within the fourth dual-mode time (dmt 12b ) continues to decrease continuously. At a first transmission start time (t 1s ) begins in the example of Fig. 14 the first ultrasonic transducer (US1) also in a fixed phase relationship to the transmission of the second ultrasonic transducer (US2) with the transmission of a second ultrasonic subburst of the ultrasonic signal at a first start frequency (f 1s ) corresponding to a first excitation start frequency [f A1s ] for the second control frequency (f A2 ) of the three ultrasound transducers (US1, US2, US3) in the example of Fig. 14 jointly controlled excitation signal (AS). The special feature here is that the first ultrasonic transducer (US1) operates at two frequencies, with the first instantaneous ultrasonic frequency (f m1 ) and with the second instantaneous ultrasonic frequency (f m2 ), must oscillate. This is not always possible. Usually, at this time, the instantaneous control frequencies (f A1 , f A2 ) are so close together that the oscillation of the first ultrasonic transducer (US1) is beaten.

[0185] This begins a second tri-mode period (dmt 12 ), in which the first ultrasonic transducer (US1) with the first instantaneous ultrasonic frequency (f m1 ) and simultaneously with the second instantaneous ultrasonic frequency (f m2 ) emits sound and the second ultrasonic transducer (US2) with the second instantaneous ultrasonic frequency (f m2) emits sound, with the first ultrasonic transducer operating at two instantaneous ultrasonic frequencies (f m1 and f m2 ) oscillates.

[0186] The control device (AS) of the three ultrasonic transducers (US1, US2, US3) lowers in the example of Fig. 14 now the current first control frequency (f A1 ) and the current second control frequency (f A2 ) and thus the first instantaneous ultrasonic frequency (f m1 ) and the second instantaneous ultrasonic frequency (f m2 ) within the second tri-mode time (tmt 112 ), in which the first ultrasonic transducer (US1) and the second ultrasonic transducer (US2) emit sound, continues to emit sound. At a second end of transmission time (t 2e ) stops in the example of Fig. 14 the second ultrasonic transducer (US2) transmits an ultrasonic signal with the second instantaneous ultrasonic frequency (f m2 ) at a second final frequency (f 2e) corresponding to a second excitation end frequency [f A2e ] for the second control frequency (f A1 ) of the second signal component of the three ultrasonic transducers (US1, US2, US3) in the example of Fig. 14 jointly controlling excitation signal (AS). In this example, this is where the Fig. 14 a final dual-mode time (dmt 11b ), in which only the first ultrasonic transducer (US1) emits sound. The first ultrasonic transducer (US1) initially oscillates at two instantaneous ultrasonic frequencies (f m1 , f m2 ). Towards the end, the Fig. 14 the frequency difference between the first instantaneous ultrasonic frequency (f m1 ) and the second instantaneous ultrasonic frequency (f m2 ) until finally the two instantaneous ultrasonic frequencies (f m1 , f m2 ) in the example of Fig. 14 are equal.

[0187] The control device of the three ultrasonic transducers (US1, US2, US3) lowers in the example of the Fig. 14 thus the current first control frequency (f A1 ) and the current second control frequency (f A2 ) within the last dual-mode time (dmt 11b ), in which only the first ultrasonic transducer (US1) emits sound, continues to emit sound. At a first end of transmission time (t 1e ) stops in the example of Fig. 14 the first ultrasonic transducer (US1) transmits the proportional ultrasonic signal at a first final frequency (f 1e ) corresponding to a first excitation end frequency [f A1e ] for the current first control frequency (f A1 ) and the current second control frequency (f A2 ) of the three ultrasound transducers (US1, US2, US3) in the example of Fig. 14 jointly controlling excitation signal (AS). In this example, this ends the Fig. 14 the emission of the ultrasonic burst (US) and thus the burst duration (bd). The sound emission then ends. Figure 15

[0188] Fig. 15 shows a simplified and schematic illustration of an exemplary system for generating the exemplary frequency response of the following Fig. 16. For example, an ultrasonic sensor system (USS) is used according to Fig. 11 used.

[0189] In contrast to the system of Fig. 13, the first ultrasonic transducer (US1) now has its own first control device (AV1). The second ultrasonic transducer (US2) now has its own second control device (AV2). The third ultrasonic transducer (US3) now has its own third control device (AV3).

[0190] The first control device (AV1) controls the first ultrasonic transducer (US1) using a first control signal (AS1).

[0191] The second control device (AV2) controls the second ultrasonic transducer (US2) using a second control signal (AS2).

[0192] The third control device (AV3) controls the third ultrasonic transducer (US3) using a third control signal (AS3).

[0193] A control unit (SG) controls the first control device (AV1) via a data bus (DB).

[0194] The control unit (SG) controls the second control device (AV2) via the data bus (DB).

[0195] The control unit (SG) controls the third control device (AV3) via the data bus (DB).

[0196] Preferably, the control devices (AV1, AV2, AV3) are synchronized via the data bus. In this case, the control devices (AV1, AV2, AV3) preferably contain their own time bases, for example, clock generators or timers, which maintain synchronization for a sufficiently long period of time without additional synchronization signals from the control unit (SG).

[0197] Thus, the ultrasonic transducers (US1, US2, US3) of the plurality of ultrasonic transducers (US1, US2, US3) can be controlled with the same or different control frequencies (f A1 , f A2 , f A3 ) of the control signals (AS1, AS2, AS3) are excited to oscillate individually and independently. However, the ultrasonic transducers (US1, US2, US3) only oscillate when the current control frequencies (f A1 , f A2 , f A3 ) of the respective control signals (AS1, AS2, AS3) lie within their respective associated bandwidth (Δf1, Δf2, Δf3). Figure 16

[0198] Fig. 16 corresponds to the Fig. 12 with the difference that now a first frequency response (SF1) of the first instantaneous excitation frequency (f A1 ) a first signal component of the control signal (AS) for generating an ultrasonic burst (UB) together with a second frequency response (SF2) of the second instantaneous excitation frequency (f A2 ) a second signal component of the control signal (AS) for generating an ultrasonic burst (UB) and together with a third frequency response (SF3) of the third instantaneous excitation frequency (f A3 ) of a third signal component of the control signal (AS) for generating an ultrasonic burst (UB). As a result, the ultrasonic sensor system (USS) at least temporarily emits an ultrasonic signal that comprises a first ultrasonic subburst with a first instantaneous ultrasonic frequency (f m1) and a second ultrasonic subburst with a second ultrasonic instantaneous frequency (f m2 ) and a third ultrasonic subburst with a third ultrasonic instantaneous frequency (f m3 ) summed up and superimposed.

[0199] The corresponding signal can be transmitted by means of a device corresponding Fig. 15, as well as by means of a device corresponding Fig. 13 are generated.

[0200] Since the first frequency response (SF1) remains completely within the first bandwidth (Δf1) of the first ultrasonic transducer (US1), it is possible to generate this part of the ultrasonic burst only with the first ultrasonic transducer (US1), wherein the first ultrasonic transducer is then controlled with a first control signal (AS1) that preferably only controls the first control frequency (f A1). The first ultrasonic transducer (US1) then emits a first ultrasonic subburst with the first instantaneous ultrasonic frequency (f m1 ) corresponding to the first control frequency (f A1 ) corresponds.

[0201] Since the second frequency response (SF2) remains completely within the second bandwidth (Δf2) of the second ultrasonic transducer (US2), it is possible to generate this part of the ultrasonic burst only with the second ultrasonic transducer (US2), whereby the second ultrasonic transducer is then controlled with a second control signal (AS2) that preferably only controls the second control frequency (f A2 ). The second ultrasonic transducer (US2) then emits a second ultrasonic subburst with the second instantaneous ultrasonic frequency (f m2 ) corresponding to the second control frequency (f A2 ) corresponds.

[0202] Since the third frequency response (SF3) remains completely within the third bandwidth (Δf3) of the third ultrasonic transducer (US3), it is possible to generate this part of the ultrasonic burst only with the third ultrasonic transducer (US3), whereby the third ultrasonic transducer is then controlled with a third control signal (AS3) that preferably only controls the third control frequency (f A3 ). The third ultrasonic transducer (US3) then emits a third ultrasonic subburst with the third instantaneous ultrasonic frequency (f m3 ) corresponding to the third control frequency (f A3 ) corresponds.

[0203] At a first transmission start time (t 1s ) the first ultrasound transducer (US1) starts with the first start frequency (f 1s ) as the first instantaneous ultrasonic frequency (f m1 ) and to oscillate its sound signal with this first instantaneous ultrasonic frequency (f m1). For this purpose, a control device (AV) or a first control device (AV1) controls the first ultrasonic transducer (US1) with a current first control frequency (f A1 ) corresponding to the desired first ultrasonic instantaneous frequency (f m1 ) essentially corresponds to the sound radiation. In the example of the Fig. 15, the control device (AV) or the first control device (AV1) reduces the current first control frequency (f A1 ) and thus the first instantaneous ultrasonic frequency (f m1 ) of the sound radiation of the first ultrasonic transducer (US1) decreases with time. At a first transmission end time (t 1e ), the first ultrasonic transducer (US1) then stops the sound radiation at a first final frequency (f 1e ) as the first instantaneous ultrasonic frequency (f m1 ).

[0204] At a second transmission start time (t 2s) the second ultrasonic transducer (US2) then starts with the second start frequency (f 2s ) as the second instantaneous ultrasonic frequency (f m2 ) and to oscillate its sound signal with this second ultrasonic instantaneous frequency (f m2 ). For this purpose, a control device (AV) or a second control device (AV2) controls the second ultrasonic transducer (US2) with a current second control frequency (f A2 ) corresponding to the desired second ultrasonic instantaneous frequency (f m2 ) is essentially the same. In the example of the Fig. 15, the control device (AV) or the second control device (AV2) reduces the current second control frequency (f A2 ) and thus the second instantaneous ultrasonic frequency (f m2 ) of the sound radiation of the second ultrasonic transducer (US2) decreases with time. At a second transmission end time (t 2e), the second ultrasonic transducer (US2) then stops the sound radiation at a second final frequency (f 2e ) as the second instantaneous ultrasonic frequency (f m2 ).

[0205] At a third transmission start time (t 3s ) the third ultrasound transducer (US3) then starts with the third start frequency (f 3s ) as the third instantaneous ultrasonic frequency (f m3 ) and to oscillate its sound signal at the third instantaneous ultrasonic frequency (f m3 ). For this purpose, a control device (AV) or a third control device (AV3) controls the third ultrasonic transducer (US3) with a current third control frequency (f A3 ) which essentially corresponds to the desired instantaneous oscillation frequency. In the example of the Fig. 15, the control device (AV) or the third control device (AV3) reduces the current third control frequency (f A3) and thus the third instantaneous ultrasonic frequency (f m3 ) of the sound radiation of the third ultrasonic transducer (US3) decreases with time. At a third transmission end time (t 3e ), the third ultrasonic transducer (US3) then stops the sound radiation at a third final frequency (f 3e ) as the third instantaneous ultrasonic frequency (f m3 ).

[0206] In the example of Fig. 16 is the first starting time (t 1s ) before the second start time (t 2s ) and the third starting time (t 3s ). This results in a first single-mode time (smt1), in which only the first ultrasonic transducer (US1) transmits sound with the first instantaneous ultrasonic frequency (f m1 ) radiates.

[0207] In the example of Fig. 16 is the second starting time (t 2s ) after the first start time (t 1s) and before the third start time (t 3s ). This results in a first dual-mode time (dmt1), in which only the first ultrasonic transducer (US1) with the first instantaneous ultrasonic frequency (f m1 ) and the second ultrasonic transducer (US2) with the second instantaneous ultrasonic frequency (f m2 ) Sound with different ultrasonic instantaneous frequencies (f m1 , f m2 ) radiate.

[0208] After the third start time (t 3s ) the third ultrasonic transducer (US3) then begins to emit sound with the third instantaneous ultrasonic frequency (f m3 ). This results in a period beginning with the third starting time (t 3s ) and ending with the first end time (t 1e) a first tri-mode time (tmt) in which all three ultrasonic transducers (US1, US2, US3) emit sound at three different frequencies. The first ultrasonic transducer (US1) emits sound at the first instantaneous ultrasonic frequency (f m1 ). The second ultrasonic transducer (US2) emits sound at the second instantaneous ultrasonic frequency (f m2 ). The third ultrasonic transducer (US3) emits sound at the third instantaneous ultrasonic frequency (f m3 ) out of.

[0209] In the example of Fig. 16 is the first end time (t 1e ) before the second end time (t 2e ) and the third end time (t 3e ). This results in a second dual-mode time (dmt2), in which only the second ultrasonic transducer (US2) operates at the second instantaneous ultrasonic frequency (f m2 ) emits sound and the third ultrasonic transducer (US3) with the third instantaneous ultrasonic frequency (fm3 ) sound. The second dual-mode time (dmt2) ends with the second end time (t 2e ).

[0210] In the example of Fig. 16 is the second end time (t 2e ) after the first end time (t 1e ) and before the third end time (t 3e ). This results in a second single-mode time (smt2), in which only the third ultrasonic transducer (US3) with the third instantaneous ultrasonic frequency (f m3 ) sound. The second single-mode time (smt2) ends with the third end time (t 3e ). This is also the end of the ultrasonic burst. Figure 17

[0211] Fig. 17 corresponds to the Fig. 12 with the difference that now a first frequency curve (SF1) of the first ultrasonic instantaneous frequency (f m1 ) of a first ultrasonic partial burst corresponding to the frequency response of the first instantaneous excitation frequency (f A1) a first signal component of the control signal (AS) for generating an ultrasonic burst (UB) together with a second frequency response (SF2) of the second instantaneous ultrasonic frequency (f m2 ) of a second ultrasonic subburst corresponding to the second instantaneous excitation frequency (f A2 ) a second signal component of the control signal (AS) for generating an ultrasonic burst (UB) and together with a third frequency curve (SF3) of the third instantaneous ultrasonic frequency (f m3 ) corresponding to the third instantaneous excitation frequency (f A3 ) a third signal component of the control signal (AS) to generate an ultrasonic burst (UB). In contrast to the previous Fig. 16 all frequency curves (SF1, SF2, SF3) now end at a common final frequency (f e ) as the respective instantaneous ultrasonic frequency (f m1 , f m2 , f m3 ) to a common end time (t e). Here, this common final frequency (f e ) is chosen so that it can be generated by all three exemplary ultrasonic transducers (US1, US2, US3). Two of the frequency responses are monotonically decreasing, one monotonically increasing. Figure 18 & Figure 19

[0212] The sound radiation of the ultrasonic sensor system (USS) corresponds to a multipole expansion of a spherical wave function, neglecting the distance between the ultrasonic sensors (US1, US2, US3) and the dimensions of the ultrasonic sensor system (USS) itself. This means that the sound radiation lobe of an ultrasonic transducer (US1, US2, US3) of the ultrasonic sensor system (USS) each has an aperture angle. The sound radiation lobe of an ultrasonic sensor has a lobe axis. If the sound radiation lobe is cut perpendicular to the lobe axis in a cross-section, the intensity distribution of the sound in this cross-section is generally not rotationally symmetrical around the point where the lobe axis passes through this cutting plane, but rather elliptical. The aperture angle of the sound radiation of an ultrasonic sensor in the vertical is often different from the aperture angle of the sound radiation in the horizontal.In the . Fig. 18, the horizontal opening angles are designated with the index H and the vertical opening angles with the index V. The Fig. 18a outlines the situation in supervision. Fig. 18b outlines the situation in side view.

[0213] The sound beam of the first ultrasonic transducer (US1) of the ultrasonic system (USS) has the vertical opening angle α v and the horizontal opening angle α H .

[0214] The sound beam of the second ultrasonic transducer (US2) of the ultrasonic system (USS) has the vertical opening angle β v and the horizontal opening angle β H .

[0215] The sound beam of the third ultrasonic transducer (US3) of the ultrasound system (USS) has the vertical opening angle γ v and the horizontal opening angle γ H .

[0216] In the example of Fig. 18, for example, the opening angles of the first ultrasonic transducer (US1) are designed to be larger than the opening angles of the second ultrasonic transducer (US2) and larger than the opening angles of the third ultrasonic transducer (US3).

[0217] In the example of Fig. 18, the opening angles of the second ultrasonic transducer (US2) are smaller than the opening angles of the first ultrasonic transducer (US1) and larger than the opening angles of the third ultrasonic transducer (US3).

[0218] The different opening angles can be designed, for example, by the membrane size in relation to the sound wavelength. The resonance frequencies can be adjusted by material selection and thickness. The choice of the excitation frequency (f A1 , f A2 , f A3 ) of the respective ultrasonic transducer (US1, US2, US3) changes the dimensions of the radiation beam.

[0219] This has the advantage that at different excitation frequencies the reflections of objects (O1, O2) that are equally far away from the ultrasound system (see also Fig. 19) by the spectral composition of the reflected signal. This makes it possible to determine the angle. Figure 20

[0220] Fig. Figure 20 illustrates how the different types of modulation described above can now be used when approaching an important object (O), for example an obstacle.

[0221] In the example of Fig. 20 the burst duration (bd) is shortened as the object (O) is approached.

[0222] The number of simultaneously transmitted frequency responses (SF1, SF2, SF3) increases from two to three when the distance between the ultrasonic sensor system (USS) and the object (O, O1, O2) falls below a certain threshold. The number of simultaneously transmitted frequency responses (SF1, SF2, SF3) therefore changes as the sensor approaches the object (O). Within an ultrasonic burst, the number of frequency responses initially increases from 1 to 2. As the sensor approaches closer, the number of frequency responses within an ultrasonic burst then increases from 1 to 3.

[0223] The frequency responses are shown in the example of Fig. 20 all always fall strictly monotonically within an ultrasonic burst, with the decay rate of the ultrasonic instantaneous frequencies (f m1 , f m2 , f m3 ) and thus the excitation frequencies (f A ) within an ultrasonic burst (UB). The starting frequency (f 1s) of the first frequency response (SF1) within an ultrasonic burst (UB) is changed as the object (O) is approached. First, the starting frequency (f 1s ) of the first frequency response (SF1) within an ultrasonic burst is increased as the object (O) approaches, and then decreases again as the object approaches. All ultrasonic bursts in the example of the Fig. 20 has a single-mode time (smt), during which only the ultrasonic subburst with the first frequency response (SF1) is transmitted. One time period of the ultrasonic burst transmission (UB) has a dual-mode time (dmt), during which only the ultrasonic subbursts with the first frequency response (SF1) and with the second frequency response (SF3) are transmitted. Another portion of the ultrasonic bursts has a tri-mode time (tmt), during which the ultrasonic subbursts with the first frequency response (SF1), with the second frequency response (SF3), and with the third frequency response (SF3) are transmitted. Figure 21

[0224] Fig. Figure 21 illustrates the situation when using two ultrasonic sensor systems (USS1, USS2).

[0225] In this example, for better explanation, each of the two exemplary ultrasonic sensor systems (USS1, USS2) corresponds approximately to the exemplary ultrasonic sensor system (USS) of the Fig. 11.

[0226] Each of the ultrasonic sensor systems (USS1, USS2) receives the corresponding signals when using different aperture angles. Fig. 18 and different ultrasonic instantaneous frequencies (f m1 , f m2 , f m3 ) within an ultrasonic sensor system, three different ultrasonic reflection signals with different instantaneous ultrasonic frequencies (f m1 , f m2 , f m3). These three received ultrasonic reflection signals, as an example, can be evaluated in the ultrasonic sensor system (USS1, USS2) and then transmitted to a control unit (SG), or they can be compressed without evaluation and largely unprocessed, transmitted to a control unit (SG), and then evaluated in the control unit (SG). Depending on the distance (D, s1, s2) of the object (O) from the respective ultrasonic sensor system (USS1, USS2), the ultrasonic reflection signal arrives at the respective ultrasonic sensor system (USS1, USS2) at different times, which can also be evaluated. Figure 22

[0227] Fig. Figure 22 shows the effect of different ultrasound bursts on their Doppler resistance.

[0228] Fig. Figure 22 shows four examples of the influence of the ultrasonic burst frequency bandwidth and the frequency modulation curvature on Doppler-related range errors at a travel speed of 8 ms -1 The top row shows spectrograms of four ultrasonic burst echo pairs. The bottom row shows the envelopes of the corresponding cross-correlation function (CCF) signal between the ultrasonic burst signal emitted by the moving vehicle and the signal reflected by a stationary object after reception by the ultrasonic sensor system located in the moving vehicle. The arrows indicate the actual time delay of 8 ms between the time of transmission and the time of reception of the echo. The vertical lines indicate the position of the peak in the CCF signal.

[0229] As can easily be seen, a greater broadband of the ultrasound burst leads to a reduction of the Doppler error. For frequency measurement of simultaneously present frequencies

[0230] For greater clarity, we briefly mention here how the presence of multiple frequencies at one time should be measured.

[0231] Samples of the signal to be evaluated are continuously saved as memory values. A storage time can always be assigned to the memory values. The memory values ​​are multiplied by a window signal. This can be one of the following window signals, for example: rectangular window, von Hann window, Hamming window, Blackman window, Blackman-Harris window, Blackman-Nuttall window, flat-top window, Bartlett window, Bartlett-Hann window, cosine window, Tukey window, Lanczos window, Kaiser window, Gaussian window. Other window types are conceivable. The window function has a reference time. The temporal length of the respective window should be less than the ultrasound burst duration (bd). Preferably, the temporal length of the respective window should be less than 1 / 10 of the ultrasound burst duration (bd). The memory values ​​are multiplied by the window function for the respective reference time.In this process, a stored value is always multiplied by the value of the window signal to produce a windowed sample whose time within the window signal corresponds to the sampling time of the stored value, taking the reference time into account. The windowed samples then produce a windowed signal that can be subjected to a Fourier transform or a Z-transform. If multiple frequencies are evident in the transformed signal, then multiple frequencies are present in the signal at the reference time. The reference time is shifted, and the same analysis is repeated over and over again. This process is known as time-frequency analysis (TFA). List of reference symbols A Ultrasound burst amplitude; A1 first spectral ultrasound burst amplitude of the first ultrasound transducer (US1); A2 second spectral ultrasonic burst amplitude of the second ultrasonic transducer (US2); A3 third spectral ultrasound burst amplitude of the third ultrasound transducer (US3); A max1 first amplitude maximum (A max1 ) of the sound radiation of the first ultrasonic transducer (US1) at its first resonance frequency (f1). The first amplitude maximum (A max1 ) of the sound radiation can be determined by exciting the first ultrasonic transducer (US1) with a first excitation frequency (f A1 ) are measured, with the first excitation frequency (f A1 ) and the first excitation frequency (f A1 ) at which the first ultrasonic transmitter (US1) absorbs the maximum effective power. The radiated sound power is referred to in this document as the first amplitude maximum (A max1 ) the sound radiation of the first ultrasonic transducer (US1); A max2 second amplitude maximum (A max2) of the sound radiation of the second ultrasonic transducer (US2) at its second resonance frequency (f2). The second amplitude maximum (A max2 ) of the sound radiation can be achieved by exciting the second ultrasonic transducer (US2) with a second excitation frequency (f A2 ), whereby the second excitation frequency (f A2 ) and the second excitation frequency (f A2 ) at which the second ultrasonic transmitter (US2) absorbs the maximum effective power. The radiated sound power is referred to in this document as the second amplitude maximum (A max2 ) the sound radiation of the second ultrasonic transducer (US2); A max3 third amplitude maximum (A max3 ) of the sound radiation of the third ultrasonic transducer (US3) at its third resonance frequency (f3). The third amplitude maximum (A max3) of the sound radiation can be achieved by exciting the third ultrasonic transducer (US3) with a third excitation frequency (f A3 ), whereby the third excitation frequency (f A3 ) and the third excitation frequency (f A3 ) at which the third ultrasonic transmitter (US3) absorbs the maximum effective power. The radiated sound power is referred to in this document as the third amplitude maximum (A max3 ) the sound radiation of the third ultrasonic transducer (US3); AS control signal; AS1 first control signal of the first ultrasonic transducer (US1); AS2 first control signal of the second ultrasonic transducer (US2); AS3 first control signal of the third ultrasonic transducer (US3); AV control device; AV1 first control device of the first ultrasonic transducer (US1); AV2 second control device of the second ultrasonic transducer (US2); AV3 third control device of the third ultrasonic transducer (US3); bd Burst duration of an ultrasonic burst. The burst duration begins with the ultrasonic burst start (UBS) and ends with the ultrasonic burst end (UBE); D Object distance between the nearest relevant object and the ultrasonic measuring system; Δf1 first bandwidth of the first ultrasound transducer (US1). The first bandwidth is the first upper half-maximum amplitude frequency (f 1o ), at which the amplitude (A) of the sound radiation of the first ultrasonic transducer (US1) is half of the first amplitude maximum (A max1 ) of the sound radiation of the first ultrasonic transducer (US1) at its first resonance frequency (f1), minus the first lower half-maximum amplitude frequency (f 1u), at which the amplitude (A) of the sound radiation of the first ultrasonic transducer (US1) is also half of the first amplitude maximum (A max1 ) the sound radiation of the first ultrasonic transducer (US1) at its first resonance frequency (f1); Δf 12 Frequency difference between the first resonance frequency (f1) of the first ultrasonic transducer (US1) and the second resonance frequency (f2) of the second ultrasonic transducer (US2); Δf2 second bandwidth of the second ultrasound transducer (US2). The second bandwidth is the second upper half-maximum amplitude frequency (f 2o ), at which the amplitude (A) of the sound radiation of the second ultrasonic transducer (US2) is half of the second amplitude maximum (A max2 ) of the sound radiation of the second ultrasonic transducer (US2) at its second resonance frequency (f2), minus the second lower half-maximum amplitude frequency (f 2u), at which the amplitude (A) of the sound radiation of the second ultrasonic transducer (US2) is also half of the second amplitude maximum (A max2 ) the sound radiation of the second ultrasonic transducer (US2) at its second resonance frequency (f2); Δf 23 Frequency difference between the second resonance frequency (f2) of the second ultrasonic transducer (US2) and the third resonance frequency (f3) of the third ultrasonic transducer (US3); Δf3 third bandwidth of the third ultrasound transducer (US3). The third bandwidth is the third upper half-maximum amplitude frequency (f 3o ), at which the amplitude (A) of the sound radiation of the third ultrasonic transducer (US3) is half of the third amplitude maximum (A max3 ) of the sound radiation of the third ultrasonic transducer (US3) at its third resonance frequency (f3), minus the third lower half-maximum amplitude frequency (f 3u), at which the amplitude (A) of the sound radiation of the third ultrasonic transducer (US3) is also half of the third amplitude maximum (A max3 ) the sound radiation of the third ultrasonic transducer (US3) at its third resonance frequency (f3); Δf g Total frequency bandwidth of the ultrasonic sensor system (USS); dmt 12 second dual-mode time in Fig. 12, in which the first ultrasonic transducer (US1) and the second ultrasonic transducer (US2) emit sound; dmt 23 first dual-mode time in Fig. 12, in which the third ultrasonic transducer (US3) and the second ultrasonic transducer (US2) emit sound; f1 first resonance frequency of the first ultrasonic transducer (US1). The first resonance frequency of the first ultrasonic transducer (US1) is determined in accordance with this document such that the first amplitude maximum (A max1) of the sound radiation of the first ultrasonic transducer (US1) by detuning the first excitation frequency (f A1 ) of the first ultrasonic transducer (US1) is sought with the excitation amplitude of the first excitation signal (AS1) of the first ultrasonic transducer (US1) preferably remaining at least locally constant over time. The first amplitude maximum (A max1 ) can be achieved by exciting the first ultrasonic transducer (US1) with a first excitation frequency (f A1 ) are measured, with the first excitation frequency (f A1 ) and the first excitation frequency (f A1 ) at which the first ultrasonic transmitter (US1) absorbs the maximum effective power. The radiated sound power is referred to in this document as the first amplitude maximum (A max1 ) of the sound radiation of the first ultrasonic transducer (US1). The first excitation frequency (f A1) at which this first amplitude maximum (A max1 ) is the first resonance frequency of the first ultrasonic transducer (US2); f 1 / 50% first half frequency. The first half frequency is given by f 1 / 50% =(f 1s -f 1e ) / 2+f 1e ; f 1e first final frequency; f 1m first ultrasonic burst instantaneous frequency at which the first ultrasonic transmitter (US1) emits sound; f 1o first upper half-maximum amplitude frequency (f 1o ). At the first upper half-maximum amplitude frequency (f 1o ) the amplitude (A) of the sound radiation of the first ultrasonic transducer (US1) is half of the first amplitude maximum (A max1 ) of the sound radiation of the first ultrasonic transducer (US1) at its first resonance frequency (f1). The first upper half-maximum amplitude frequency (f 1o) of the first ultrasonic transducer (US1) is above the first resonance frequency (f1) of the first ultrasonic transducer (US1); f 1s first starting frequency; f 1u first lower half-maximum amplitude frequency (f 1u ). At the first lower half-maximum amplitude frequency (f 1u ) the amplitude (A) of the sound radiation of the first ultrasonic transducer (US1) is half of the first amplitude maximum (A max1 ) of the sound radiation of the first ultrasonic transducer (US1) at its first resonance frequency (f1). The first lower half-maximum amplitude frequency (f 1u ) of the first ultrasonic transducer (US1) is below the first resonance frequency (f1) of the first ultrasonic transducer (US1); f2 second resonance frequency of the second ultrasonic transducer (US2). The second resonance frequency of the second ultrasonic transducer (US2) is determined in accordance with this document such that the second amplitude maximum (A max2 ) of the sound radiation of the second ultrasonic transducer (US2) by detuning the second excitation frequency (f A2 ) of the second ultrasonic transducer (US2) is sought with the excitation amplitude of the second excitation signal of the second ultrasonic transducer (US2) preferably remaining at least locally constant over time. The second amplitude maximum (A max2 ) can be achieved by exciting the second ultrasonic transducer (US2) with a second excitation frequency (f A2 ), whereby the second excitation frequency (f A2 ) and the second excitation frequency (f A2) at which the second ultrasonic transmitter (US2) absorbs the maximum effective power. The radiated sound power is referred to in this document as the second amplitude maximum (A max2 ) of the sound radiation of the second ultrasonic transducer (US2). The second excitation frequency (f A2 ) at which this second amplitude maximum (A max2 ) is the second resonance frequency of the second ultrasonic transducer (US2); f 2 / 50% second half frequency. The second half frequency is given by f 2 / 50% =(f 2s -f 2e ) / 2+f 2e ; f 2e second final frequency; f 2m second ultrasonic burst instantaneous frequency at which the second ultrasonic transmitter (US2) emits sound; f 2o second upper half-maximum amplitude frequency (f 2o ). At the second upper half-maximum amplitude frequency (f 2o), the amplitude (A) of the sound radiation of the second ultrasonic transducer (US2) is half of the second amplitude maximum (A max2 ) of the sound radiation of the second ultrasonic transducer (US2) at its second resonance frequency (f2). The second upper half-maximum amplitude frequency (f 2o ) of the second ultrasonic transducer (US2) is above the second resonance frequency (f2) of the second ultrasonic transducer (US2); f 2s second starting frequency; f 2u second lower half-maximum amplitude frequency (f 2u ). At the second lower half-maximum amplitude frequency (f 2u ), the amplitude (A) of the sound radiation of the second ultrasonic transducer (US2) is half of the second amplitude maximum (A max2 ) of the sound radiation of the second ultrasonic transducer (US2) at its second resonance frequency (f2). The second lower half-maximum amplitude frequency (f 2u) of the second ultrasonic transducer (US2) is below the second resonance frequency (f2) of the second ultrasonic transducer (US2); f3 third resonance frequency of the third ultrasonic transducer (US3). The third resonance frequency of the third ultrasonic transducer (US3) is determined in accordance with this document such that the third amplitude maximum (A max3 ) of the sound radiation of the third ultrasonic transducer (US3) by detuning the third excitation frequency (f A3 ) of the third ultrasonic transducer (US3) is sought with the excitation amplitude of the third excitation signal of the third ultrasonic transducer (US3) preferably remaining at least locally constant over time. The third amplitude maximum (A max3 ) can be achieved by exciting the third ultrasonic transducer (US3) with a third excitation frequency (f A3 ), whereby the third excitation frequency (f A3) and the third excitation frequency (f A3 ) at which the third ultrasonic transmitter (US3) absorbs the maximum effective power. The radiated sound power is referred to in this document as the third amplitude maximum (A max3 ) of the sound radiation of the first ultrasonic transducer (US1). The third excitation frequency (f A3 ) at which this third amplitude maximum (A max3 ) is the third resonance frequency of the third ultrasonic transducer (US3); f 3 / 50% third half frequency. The third half frequency is given by f 3 / 50% =(f 3s -f 3e ) / 2+f 3e ; f 3e third final frequency; f 3m third ultrasonic burst instantaneous frequency at which the third ultrasonic transmitter (US3) emits sound; f 3o third upper half-maximum amplitude frequency (f 3o). At the third upper half-maximum amplitude frequency (f 3o ) the amplitude (A) of the sound radiation of the third ultrasonic transducer (US3) is half of the third amplitude maximum (A max3 ) of the sound radiation of the third ultrasonic transducer (US3) at its third resonance frequency (f3). The third upper half-maximum amplitude frequency (f 3o ) of the third ultrasonic transducer (US3) is above the third resonance frequency (f3) of the third ultrasonic transducer (US3); f 3s third starting frequency; f 3u third lower half-maximum amplitude frequency (f 3u ). At the third lower half-maximum amplitude frequency (f 3u ) the amplitude (A) of the sound radiation of the third ultrasonic transducer (US3) is half of the third amplitude maximum (A max3) of the sound radiation of the third ultrasonic transducer (US3) at its third resonance frequency (f3). The third lower half-maximum amplitude frequency (f 3u ) of the third ultrasonic transducer (US3) is below the third resonance frequency (f3) of the third ultrasonic transducer (US3); f A Control instantaneous frequency; f A1 first control frequency of the first ultrasonic transducer (US1); f A1 / 50% first half-frequency control frequency; f A1e first final control frequency; f A1s first start control frequency; f A2 second control frequency of the second ultrasonic transducer (US2); f A2 / 50% second half-frequency control frequency; f A2e second final control frequency; f A2s second start control frequency; f A3 third control frequency of the third ultrasonic transducer (US3); f A3 / 50% third half-frequency control frequency; f A3e third final control frequency; f A3s third start control frequency; f m Ultrasonic burst instantaneous frequency; f m,0 zeroth ultrasonic instantaneous frequency of the zeroth ultrasonic pulse (P0) in the zeroth ultrasonic period with the zeroth ultrasonic period duration (T0) within an ultrasonic burst (UB); f m,1 first ultrasonic instantaneous frequency of the first ultrasonic pulse (P1) in the first ultrasonic period with the first ultrasonic period duration (T1) within an ultrasonic burst (UB); f m,2 second ultrasonic instantaneous frequency of the second ultrasonic pulse (P2) in the second ultrasonic period with the second ultrasonic period duration (T2) within an ultrasonic burst (UB); f m,3third ultrasonic instantaneous frequency of the third ultrasonic pulse (P3) in the third ultrasonic period with the third ultrasonic period duration (T3) within an ultrasonic burst (UB); f m,4 fourth ultrasonic instantaneous frequency of the fourth ultrasonic pulse (P4) in the fourth ultrasonic period with the fourth ultrasonic period duration (T4) within an ultrasonic burst (UB); f m,5 fifth ultrasonic instantaneous frequency of the fifth ultrasonic pulse (P5) in the fifth ultrasonic period with the fifth ultrasonic period duration (T5) within an ultrasonic burst (UB); f m,6 sixth ultrasonic instantaneous frequency of the sixth ultrasonic pulse (P6) in the sixth ultrasonic period with the sixth ultrasonic period duration (T6) within an ultrasonic burst (UB); f m,7seventh ultrasonic instantaneous frequency of the seventh ultrasonic pulse (P7) in the seventh ultrasonic period with the seventh ultrasonic period duration (T7) within an ultrasonic burst (UB); f m,j j-th instantaneous ultrasonic frequency of the j-th ultrasonic pulse (P j ) in the j-th ultrasound period with the j-th ultrasound period duration (T j ) within an ultrasonic burst (UB) (here j stands for a positive integer); O object; O1 first object; O2 second object; P0 zeroth ultrasonic pulse in the zeroth ultrasonic period of the exemplary ultrasonic burst (UB) of the Fig. 2a; P1 first ultrasonic pulse in the first ultrasonic period of the exemplary ultrasonic burst (UB) of the Fig. 2a; P2 second ultrasonic pulse in the second ultrasonic period of the exemplary ultrasonic burst (UB) of the Fig. 2a; P3 third ultrasonic pulse in the third ultrasonic period of the exemplary ultrasonic burst (UB) of the Fig. 2a; P4 fourth ultrasonic pulse in the fourth ultrasonic period of the exemplary ultrasonic burst (UB) of the Fig. 2a; P5 fifth ultrasonic pulse in the fifth ultrasonic period of the exemplary ultrasonic burst (UB) of the Fig. 2a; P6 sixth ultrasonic pulse in the sixth ultrasonic period of the exemplary ultrasonic burst (UB) of the Fig. 2a; P7 seventh ultrasonic pulse in the seventh ultrasonic period of the exemplary ultrasonic burst (UB) of the Fig. 2a; P j j-th ultrasonic pulse in the j-th ultrasonic period of the exemplary ultrasonic burst (UB) (here j stands for a positive integer); SF1 first frequency response of the ultrasonic burst instantaneous frequency (f m ) or the first ultrasonic burst instantaneous frequency (f m1) a first ultrasonic subburst within an ultrasonic burst (UB); SF2 second frequency response of the second ultrasonic burst instantaneous frequency (f m2 ) of a second ultrasonic subburst within an ultrasonic burst (UB). Within the ultrasonic burst (UB), this second ultrasonic subburst is typically superimposed on the first ultrasonic subburst, preferably by summation; SF3 third frequency response of the third ultrasonic burst instantaneous frequency (f m3 ) of a third ultrasonic subburst within an ultrasonic burst (UB). Within the ultrasonic burst (UB), this third ultrasonic subburst is typically superimposed on the first ultrasonic subburst and the second ultrasonic subburst, preferably by summation; s1 first distance of the first ultrasonic sensor system (USS1) from the object (O) s2 second distance of the second ultrasonic sensor system (USS2) from the object (O) smt1 first single-mode time; smt2 second single-mode time; smt3 third single-mode time; USA ultrasound system axis; USS Ultrasonic Sensor System; USS1 first ultrasonic sensor system; USS2 second ultrasonic sensor system; t time; t 1 / 50% first half-frequency time. At this first half-frequency time (t 1 / 50% ), the first ultrasonic transducer (US1) transmits at a first half frequency (f 1 / 50% ); t 1a first temporal burst phase; t 1b second temporal burst phase; t 1s first broadcast start time; t 1e first broadcast end time; t 2 / 50% second half-frequency time. At this second half-frequency time (t 2 / 50% ), the second ultrasonic transducer (US2) transmits at a second half frequency (f 2 / 50% ); t 2ssecond broadcast start time; t 2e second transmission end time; t 3 / 50% third half-frequency time point. At this third half-frequency time point (t 3 / 50% ), the third ultrasonic transducer (US3) transmits at a second half frequency (f 3 / 50% ); t 3s third broadcast start time; t 3e third broadcast end time; T0 zeroth ultrasonic period duration of the zeroth ultrasonic period of the zeroth ultrasonic pulse (P0); T1 first ultrasound period duration of the first ultrasound period of the first ultrasound pulse (P1); T2 second ultrasound period duration of the second ultrasound period of the second ultrasound pulse (P2); T3 third ultrasound period duration of the third ultrasound period of the third ultrasound pulse (P3); T4 fourth ultrasound period duration of the fourth ultrasound period of the fourth ultrasound pulse (P4); T5 fifth ultrasound period duration of the fifth ultrasound period of the fifth ultrasound pulse (P5); T6 sixth ultrasound period duration of the sixth ultrasound period of the sixth ultrasound pulse (P6); T7 seventh ultrasound period duration of the seventh ultrasound period of the seventh ultrasound pulse (P7); T j j-th ultrasonic period duration of the j-th ultrasonic period of the j-th ultrasonic pulse (P j ) (here j stands for a positive integer); UB ultrasonic burst; UBS ultrasonic burst launch; UBE ultrasonic burst end US1 first ultrasound transducer; US2 second ultrasound transducer; US3 third ultrasound transducer; USS Ultrasonic Sensor System; USS1 first ultrasonic sensor system; USS2 second ultrasonic sensor system; v fFrequency change rate of the ultrasonic burst instantaneous frequency (f m ) over time (t);

Claims

[1] A method for transmitting an ultrasonic burst for use in ultrasonic sensor systems in vehicles, comprising the steps - Step 1: Emission of an ultrasonic burst with an ultrasonic burst duration (bd) not exceeding a maximum ultrasonic burst duration (bd) by an ultrasonic sensor system (USS); - Step 2: Receiving an ultrasonic burst reflected by an object (O); - Step 3: Determining the distance (D) between the ultrasonic sensor system (USS) and the object (O) as a function of the received reflected ultrasonic burst; - Step 4: Repeating steps 1 to 4, wherein the ultrasonic burst duration (bd) depends on the determined distance (D, s1, s2), characterized in that - that at least several ultrasonic bursts (UB) are emitted at a temporal ultrasonic burst interval and - that the first temporal ultrasonic burst interval is the time interval between the ultrasonic burst start (UBS) of a first ultrasonic burst and the ultrasonic burst start (UBS) of the second ultrasonic burst immediately following this first ultrasonic burst and - that the second temporal ultrasonic burst interval between the ultrasonic burst start (UBS) of the second ultrasonic burst and the ultrasonic burst start (UBS) of the third ultrasonic burst immediately following this second ultrasonic burst depends on the determined distance (D) and - wherein the ultrasonic burst length of the ultrasonic burst duration (bd) is increased by the fourth root of the determined distance (D). [2] Method according to claim 1, - where the amplitude (A) of the emitted ultrasonic burst is substantially proportional to (D+D0) 1 / k, with 2≤k≤5 or preferably k=2 or k=4, depends on the determined distance (D), where D0 is a constant that can be zero. [3] Method according to one or more of claims 1 to 2, - whereby the temporal ultrasonic burst spacing of the ultrasonic bursts becomes shorter with decreasing spatial distance (D) between the ultrasonic sensor system and the object (O). [4] Method according to claim 3, - wherein the temporal ultrasonic burst spacing of the ultrasonic bursts becomes shorter by a time 2*I / c with c as the speed of sound with a tolerance of + / - 25% and / or with a tolerance of + / - 10% and / or with a tolerance of + / - 5% when the spatial distance (D) between the ultrasonic sensor system and the object (O) is shortened by a length I. [5] Method according to one or more of claims 1 to 4 - where the number of ultrasonic burst instantaneous frequencies (f m1 , f m2 , f m3) and the corresponding number of frequency responses (SF1, SF2, SF3) of these ultrasonic burst instantaneous frequencies (f m1 , f m2 , f m3 ) within an ultrasonic burst (UB) depends on the distance (D).

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