Method for operating an ultrasonic sensor device for a motor vehicle, wherein two ultrasonic signals are emitted at least partially simultaneously, ultrasonic sensor device and motor vehicle

Abstract

Method for operating an ultrasonic sensor device (5) for a motor vehicle (1), which has at least one first ultrasonic sensor (5a') and at least one second ultrasonic sensor (5a''), wherein a first ultrasonic sound signal (8') is emitted into the environment (4) by means of the first ultrasonic sensor (5a') and a second ultrasonic sound signal (8'') is emitted by means of the second ultrasonic sensor (5a'') for determining the distance of an object (3', 3'') in an environment (4) of the motor vehicle (1), wherein the ultrasonic signals (8', 8'') of the ultrasonic sensors (5a', 5a'') are emitted with the same frequency profile, wherein for this purpose the first ultrasonic sensor (5a') is controlled by a first control signal (C1) and the second ultrasonic sensor (5a'') by a second control signal (C2), characterized in that the first control signal (C1) is generated in such a way thatthat the first control signal (C1) has at least one first excitation phase (A1) for generating the first ultrasound signal (8'), and the second control signal (C2) is generated such that the second control signal (C2) has at least one second excitation phase (A2) for generating the second ultrasound signal (8''), wherein the two control signals (C1, C2) are generated such that a first temporal start (B1) of the first excitation phase (A1) is temporally offset from a second temporal start (B2) of the second excitation phase (A2), and the first excitation phase (A1) and the second excitation phase (A2) overlap at least partially in time.

Description

[0001] The invention relates to a method for operating an ultrasonic sensor device for a motor vehicle. The ultrasonic sensor device has at least a first ultrasonic sensor and at least one second ultrasonic sensor. A first ultrasonic signal is emitted by the first ultrasonic sensor, and a second ultrasonic signal is emitted by the second ultrasonic sensor to determine a distance of an object in the surroundings of the motor vehicle. The ultrasonic signals from the ultrasonic sensors are emitted with the same frequency characteristic, with the first ultrasonic sensor being controlled by a first control signal and the second ultrasonic sensor by a second control signal. The invention further relates to an ultrasonic sensor device and a motor vehicle.

[0002] The present interest is particularly directed at ultrasonic transducer devices, which can also be referred to as ultrasonic sensor devices, for motor vehicles. Such ultrasonic transducer devices can, for example, have multiple ultrasonic transducers or ultrasonic sensors, which can be arranged, for example, on the bumper of the motor vehicle. Such ultrasonic transducer devices are used, for example, in parking assistance systems that assist the driver when parking into a parking space. The ultrasonic transducer can detect objects in the surrounding area and determine the distance to the objects. The transmission power and reception sensitivity are calibrated during production. With the aim of object detection, they emit a respective ultrasonic signal, which is reflected by objects.The analysis of the received echoes of the ultrasonic signals then allows conclusions to be drawn about the position and type of the object. For example, the echoes or reflected ultrasonic signals can be used to distinguish between a tall and a short object.

[0003] Ultrasonic sensor devices are known from the prior art in which the ultrasonic signals from the ultrasonic sensors are emitted at a single frequency. Scanning the relevant environment therefore takes a very long time, as crosstalk and long-range noise would disrupt the current measurement or the next measurement in a defined measurement sequence. In static scenes, long-range noise is varied between individual steps in the measurement sequence to prevent it from repeatedly delivering the same distance. These long-range noises can still occur, but are filtered out by the fact that the distance delivered varies greatly, preventing misinterpretation. The problem of crosstalk is avoided by ensuring that only ultrasonic sensors that are far apart from one another simultaneously emit an ultrasonic signal at the same frequency.These ultrasonic sensors can, in particular, be the side ultrasonic sensors on an installed automotive component. However, crosstalk can also occur due to multiple reflections from multiple objects.

[0004] With newer ultrasonic sensors, the ultrasonic signal can be transmitted and received simultaneously at two frequencies. This reduces the time required to scan the vehicle's surroundings once, as two ultrasonic sensors can transmit an ultrasonic signal simultaneously. Variable pause times between individual steps filter out long-distance signals. However, this design increases the likelihood of crosstalk between two sensors that perform the same measurement mode at the same time or transmit the same frequency at the same time.

[0005] JP 2006 298 266 A discloses an ultrasonic sensor device comprising a plurality of ultrasonic sensors, wherein the ultrasonic sensors are assigned to a first and second group, respectively. For distance measurement, all ultrasonic sensors of the first group are activated first, followed by all sensors of the second group. DE 10 2008 002 232 A1 relates to an adaptive method for distance measurement using an ultrasonic sensor, in which a first ultrasonic pulse is emitted, reflected by an object, and received as an echo signal. To shorten the time between two measurements, the emission of a second ultrasonic pulse is triggered by the reception of the echo of the first ultrasonic pulse.

[0006] DE 10 2008 039 494 A1 discloses a method for collision monitoring in a vehicle using multiple proximity sensors, each of which sends and receives signals within a measurement cycle. At least one proximity sensor already sends signals during a measurement cycle of another proximity sensor. For position determination, portions of the signal sent by the other proximity sensor can be detected in the echo signal by cross-correlating the echo signals.

[0007] DE 10 2014 116 981 A1 discloses a method for detecting an object in the surrounding area of ​​a motor vehicle. During a measurement cycle, a plurality of ultrasonic sensors are operated in successive activation phases, with a measurement being performed with the respective ultrasonic sensor during the activation phases to determine a distance between the motor vehicle and the object. During each of the activation phases, the measurement is performed after a predetermined pause time has elapsed. A random value is determined by means of a control device, and the pause time for each of the activation phases is specified based on the random value.

[0008] In the prior art system, the ultrasonic signals are emitted at staggered intervals so that they do not overlap. This increases the measurement cycle of the ultrasonic sensor device, as simultaneous transmission of the individual ultrasonic sensors is not possible.

[0009] The object of the present invention is to provide a method, an ultrasonic sensor device and a motor vehicle by means of which a measuring cycle time can be reduced when scanning an environment of the motor vehicle by the ultrasonic sensor device.

[0010] This object is achieved by a method, an ultrasonic sensor device and a motor vehicle according to the independent patent claims.

[0011] One aspect of the invention relates to a method for operating an ultrasonic sensor device for a motor vehicle. The ultrasonic sensor device has at least one first ultrasonic sensor and at least one second ultrasonic sensor. A first ultrasonic signal is emitted by the first ultrasonic sensor, and a second ultrasonic signal is emitted by the second ultrasonic sensor to determine the distance of an object in the surroundings of the motor vehicle. The ultrasonic signals from the ultrasonic sensors are emitted with the same frequency characteristic. For this purpose, the first ultrasonic sensor is controlled by a first control signal, and the second ultrasonic sensor is controlled by a second control signal.

[0012] It is provided that the first control signal is generated such that the control signal has at least a first excitation phase for generating the first ultrasonic signal, and the second control signal is generated such that the second control signal has at least a second excitation phase for generating the second ultrasonic signal. The two control signals are generated such that a first temporal start of the first excitation phase is offset in time from a second temporal start of the second excitation phase, and the first excitation phase and the second excitation phase at least partially overlap in time.

[0013] In other words, the two control signals have a transmission start delay. This means that even if crosstalk were to occur between the ultrasonic signals, a different distance would always arise, which can be easily filtered out, for example, by a control device. This also prevents false sharp objects from occurring due to crosstalk between the two ultrasonic sensors. This allows the ultrasonic sensor device to be designed much more robustly with regard to false sharp objects. The ultrasonic sensor device can therefore scan the surroundings of the motor vehicle within a shortened measuring cycle, since at least the two ultrasonic sensors transmit the respective ultrasonic signal at least partially at the same time and overlap. In particular, the term "staggered starts" refers to a temporal offset.

[0014] Overlapping in time means that the first excitation phase and the second excitation phase have at least one common duration during which the two ultrasonic signals are emitted simultaneously. Thus, only the start and end times of each excitation phase can differ from each other. In other words, the two ultrasonic signals are emitted at least partially simultaneously or with temporal overlap.

[0015] The ultrasonic sensor device can, in particular, be part of a driver assistance system of the motor vehicle. Such a driver assistance system can, for example, be a parking assistance system, a blind spot assistant, and / or an adaptive cruise control system. The ultrasonic sensors can, for example, be arranged on and / or in a bumper of the motor vehicle. The ultrasonic sensors can be arranged in corresponding recesses in the bumper. Alternatively, the ultrasonic sensors can be arranged concealed behind a bumper of the motor vehicle. The ultrasonic sensors serve to detect an object in the surroundings of the motor vehicle. In particular, the ultrasonic sensors can be used to determine a distance between the motor vehicle and an object. In a measuring cycle, the ultrasonic sensors are operated at different times, with the excitation phases of the at least two ultrasonic sensors at least partially overlapping.

[0016] During the measurement, an ultrasonic signal is emitted, particularly with the ultrasonic sensor. For this purpose, a membrane of the ultrasonic sensor can be excited to mechanical vibrations using a suitable transducer, for example a piezoelectric element. The emitted ultrasonic signal is reflected by the object and re-impinges on the membrane of the ultrasonic sensor, which is excited to mechanical vibrations as a result of the reflected ultrasonic signal. These mechanical vibrations of the membrane can in turn be recorded by the transducer and output, for example, in the form of a voltage signal. The distance between the ultrasonic sensor and the object can be determined based on the propagation time between the emission of the ultrasonic signal and the reception of the reflected ultrasonic signal.

[0017] According to an advantageous embodiment, the respective excitation phase can be identified from a respective echo signal reflected from an object, which is received by at least one receiving device of the ultrasonic sensor device. Based on the identification, the respective received echo signal can be assigned to the respective ultrasonic sensor and the respective distance to the object can be determined by means of a control device of the ultrasonic sensor device. In other words, the assignment to the respective ultrasonic sensor is made within the echo signal. By means of this direct assignment to the ultrasonic sensor, crosstalk can be filtered out. This makes it possible to clearly assign the respective transmitted ultrasonic signal to the respective ultrasonic sensor. This prevents misinterpretation within the received echo signals.In particular, this makes it possible to design the ultrasonic sensor device more robustly against blurred objects. Furthermore, it makes it possible to shorten the measurement cycle time of the ultrasonic sensor device, since at least the two ultrasonic sensors can transmit the ultrasonic signal with at least partial temporal overlap.

[0018] It has also proven advantageous if a control device is used to generate a random value for the time offset between the first start and the second start. In other words, the control device determines a random value on the basis of which the time offset is determined. In this way, a type of desynchronization of the ultrasonic signals can be achieved. This has the advantage, for example, that if two motor vehicles equipped with such a driver assistance system or such an ultrasonic sensor device fall below a minimum distance from one another, synchronous operation of the ultrasonic sensors can be prevented. It can therefore be prevented that the respective ultrasonic sensors of the two vehicles are operated synchronously in the respective excitation phases, thus preventing the measurements from being carried out synchronously.This makes it possible, in particular, for the ultrasonic signals from the other vehicle to be interpreted by the vehicle itself as echo signals. Overall, an object in the vehicle's surrounding area can thus be detected.

[0019] In particular, the time offset can be generated in the case of a plurality of time offsets in such a way that the plurality of time offsets has, for example, a predetermined mean value which is in particular in the millisecond range.

[0020] It can also be provided that the time offset is generated in such a way that it is within a predetermined time interval, in particular in the millisecond range.

[0021] In an advantageous embodiment, the temporal offset is generated such that an average of a duration of a plurality of temporal offsets amounts to three milliseconds. Due to the average of three milliseconds and the corresponding propagation speed of the ultrasonic waves in the air, this results in an average range change of approximately 50 centimeters. This temporal offset makes it possible to only record a slight loss of range despite a delay in the excitation phases. The temporal offset nevertheless allows for clear assignment to the respective echo signal of the respective ultrasonic sensor. This allows the measurement cycle to be reliably reduced in time, while at the same time the range of the ultrasonic sensor device is barely affected.

[0022] It is also advantageous if the temporal offset is generated in such a way that the temporal offset lies within a time range between one millisecond and eight milliseconds. In other words, the temporal offset can be between one millisecond and eight milliseconds. Taking into account the propagation speed of the sound waves, this results in a maximum range change of 136 centimeters. The temporal offset nevertheless allows for a clear assignment to the respective echo signal of the respective ultrasonic sensor. This enables reliable operation of the ultrasonic sensor device, while simultaneously reducing the duration of the measurement cycle.

[0023] In a further advantageous embodiment, to generate the respective ultrasonic signal of the respective ultrasonic sensor during the respective excitation phase, the respective ultrasonic sensor can be excited with a respective control signal whose respective frequency response is frequency-modulated at least in certain regions. In other words, the ultrasonic sensor can be excited, in particular, with a frequency chirp. Excitation by means of the frequency chirp allows the corresponding echo signal to be more effectively assigned to the ultrasonic sensor. This enables improved identification of the corresponding echo signal, so that the ultrasonic sensor device can be operated reliably.

[0024] In other words, the ultrasonic sensor is excited in a frequency-encoded manner. In particular, with frequency chirping, the frequency is changed over time. This provides a simple electrical excitation signal that can nevertheless be reliably assigned to the ultrasonic sensor.

[0025] According to a further advantageous embodiment, the respective frequency-modulated frequency curve can be modulated. In other words, the frequency-modulated frequency curve is a positive frequency chirp. A positive frequency chirp is a frequency-modulated signal which is temporally modulated, in particular, from a low frequency to a high frequency. By using the positive frequency chirp as an electrical excitation signal, a reliably coded electrical excitation signal can be provided, so that the assignment to the respective ultrasonic sensor can be carried out reliably. For example, it can be provided that the frequency chirp is generated with frequencies of the same frequency band. The frequency band is defined, in particular, by predetermined limits. In particular, the frequency band has a lower limit and an upper limit.Since the ultrasonic sensor, in particular, operates within a frequency band, it is advantageous to transmit or detect the ultrasonic signals only within this frequency band. The transmitted ultrasonic signals are modulated, in particular, around the resonant frequency of the ultrasonic sensor. In particular, this allows the ultrasonic sensor device to operate multiple ultrasonic sensors simultaneously, thus reducing the measurement cycle time.

[0026] It is also advantageous if the respective frequency-modulated frequency response is modulated. In other words, the modulated frequency-modulated frequency response is a negative frequency chirp. In particular, with frequency chirp, the frequency is changed over time. This makes it possible to provide a simple electrical excitation signal in order to assign the respective ultrasonic sensor. The negative frequency chirp is a frequency-modulated signal whose frequency is modulated from a high frequency to a low frequency over time. This makes it possible to assign the ultrasonic sensor to the corresponding ultrasonic signal across a larger frequency range of the ultrasonic sensor.For example, it can be provided that the excitation with the negative frequency chirp is carried out using frequencies of the same frequency band, in particular around the resonant frequency. The frequency band is defined, in particular, by predetermined limits. In particular, the frequency band has a lower limit and an upper limit. By using the negative frequency chirp, a reliable assignment of the respective ultrasonic signal to the ultrasonic sensor can be carried out. In particular, this enables the ultrasonic sensor device to operate multiple ultrasonic sensors simultaneously, so that the measurement cycle can be reduced in time.

[0027] In a further advantageous embodiment, the ultrasonic sensor device has at least a third ultrasonic sensor, wherein, within a measuring cycle of the ultrasonic sensor device, a third control signal for generating a third ultrasonic signal is generated by the third ultrasonic sensor by means of a control device at a time offset from the first control signal and the second control signal. In other words, the excitation phases of the first control signal and the second control signal do not overlap with an excitation phase of a third control signal for the third ultrasonic sensor. The start of the third control signal thus occurs after the end time of the first and second control signals. This allows for improved scanning of the surroundings of the ultrasonic sensor device. In particular, it can be provided that the ultrasonic sensor device has further ultrasonic sensors.In particular, despite the large number of ultrasonic sensors, a measurement cycle for scanning the environment can be carried out in a shorter time. This makes the ultrasonic sensor device much more robust with regard to falsely sharp objects.

[0028] For example, in one embodiment of the ultrasonic sensor device with three ultrasonic sensors, a measurement cycle can be performed in two time steps, thus scanning the environment. The first ultrasonic sensor and the second ultrasonic sensor fire in particular such that the excitation phases at least partially overlap in the first time step of the measurement cycle. The third ultrasonic sensor fires in particular in the second time step, with the second time step occurring after the first time step and the two time steps not overlapping in time.

[0029] In an advantageous embodiment, the ultrasonic sensor device has at least one further ultrasonic sensor, wherein a further control signal for generating a further ultrasonic signal is generated by means of the ultrasonic sensor device, wherein the further ultrasonic signal has a different frequency curve than the frequency curves of the first ultrasonic signal and the second ultrasonic signal, wherein the respective excitation phases of the three ultrasonic sensors at least partially overlap in time. In other words, three ultrasonic sensors can emit a respective ultrasonic signal simultaneously, at least in certain regions. For example, the first ultrasonic signals can be emitted as a positive frequency chirp and the further ultrasonic signal as a negative frequency chirp. As a result, three ultrasonic sensors can perform a distance measurement within one time step of the measuring cycle.An exact assignment of the echo signals is still possible due to the different frequency curves and the time offset, so that a measurement cycle of the ultrasonic sensor device can be carried out in a time-reduced manner.

[0030] It has further proven advantageous that the first ultrasonic signal of the first ultrasonic sensor is transmitted into a first sub-area of ​​the environment, and the second ultrasonic signal is transmitted into a second sub-area of ​​the environment that is different from the first sub-area. This prevents the ultrasonic sensors from directly influencing each other. Direct crosstalk between the two ultrasonic sensors can thus be prevented. Only crosstalk due to multiple reflections can occur, which, however, can be easily filtered out using the method according to the invention. Thus, the ultrasonic sensor device can be operated robustly, and a reduction in the time of the measurement cycle can be achieved.

[0031] It is also advantageous if the first ultrasonic sensor is excited during the first excitation phase and the second ultrasonic sensor is excited at different times during the second excitation phase, wherein a first receiving phase for receiving an echo signal from the first ultrasonic sensor has a different first time duration, in particular a longer time duration, than a second time duration of a second receiving phase for receiving an echo signal from the second ultrasonic sensor, so that at least one end time of the two receiving phases is the same in time. In particular, this makes it possible for a third ultrasonic sensor to transmit directly after the two ultrasonic signals have been transmitted. In other words, the reception of the two echo signals ends simultaneously. Directly thereafter, the third ultrasonic sensor of the ultrasonic sensor device can begin transmitting a third ultrasonic signal after the simultaneous end time.This saves time because, despite the temporal offset between the first ultrasonic signal and the second ultrasonic signal, the end times of the two reception phases are the same. In particular, the second reception phase thus has a shorter duration with regard to the reception of the second echo signal than the first reception phase. In other words, the reception of the two echo signals ends simultaneously, but the beginning of the two ultrasonic signals is different. This allows the measurement cycle of the ultrasonic sensor device to be carried out in a reduced time.

[0032] A further aspect of the invention relates to an ultrasonic sensor device having at least one first ultrasonic sensor, at least one second ultrasonic sensor and at least one control device, wherein the ultrasonic sensor device is designed to carry out a method according to one of the preceding aspects or an advantageous embodiment thereof.

[0033] Yet another aspect of the invention relates to a motor vehicle with an ultrasonic sensor device. The motor vehicle is designed, in particular, as a passenger car.

[0034] Advantageous embodiments of the method are to be regarded as advantageous embodiments of the ultrasonic sensor device and the motor vehicle. The ultrasonic sensor device and the motor vehicle have specific features that enable implementation of the method or an advantageous embodiment thereof.

[0035] Yet another independent aspect of the invention relates to a method for operating an ultrasonic sensor device for a motor vehicle, which device has at least a first ultrasonic sensor and at least one second ultrasonic sensor. A first ultrasonic signal is emitted by the first ultrasonic sensor, and a second ultrasonic signal is emitted by the second ultrasonic sensor to determine the distance of an object in the surroundings of the motor vehicle. The ultrasonic signals from the ultrasonic sensors are emitted with the same frequency characteristic, with the first ultrasonic sensor being controlled by a first control signal and the second ultrasonic sensor being controlled by a second control signal.

[0036] It is provided that the first control signal is generated such that the control signal has at least a first excitation phase for generating the first ultrasonic signal, and the second control signal is generated such that the second control signal has at least a second excitation phase for generating the second ultrasonic signal. The first control signal and the second control signal each have a pause time before the excitation phase, wherein the pause times of the respective control signals differ, wherein the first excitation phase and the second excitation phase at least partially overlap in time.

[0037] In particular, the pause times have a duration between one millisecond and eight milliseconds inclusive.

[0038] Further features of the invention emerge from the claims, the figures and the description of the figures. The features and combinations of features mentioned above in the description as well as the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figures can be used not only in the respective combination specified, but also in other combinations or on their own, without departing from the scope of the invention. Thus, embodiments are to be regarded as encompassed and disclosed by the invention that are not explicitly shown and explained in the figures, but which arise from separate combinations of features from the explained embodiments and can be produced. Embodiments and combinations of features are also to be regarded as disclosed that therefore do not have all the features of an originally formulated claim.Furthermore, embodiments and combinations of features, in particular by the embodiments set out above, are to be regarded as disclosed which go beyond or deviate from the combinations of features set out in the references to the claims.

[0039] Examples of embodiments are explained below using schematic drawings.

[0040] Showing: Fig. 1 is a schematic plan view of an embodiment of a motor vehicle with an embodiment of an ultrasonic sensor device; Fig. 2 a schematic view of a measuring cycle in a first time step of the measuring cycle; and Fig. 3 a schematic time course of a transmission process of an ultrasonic sensor device.

[0041] In the figures, identical or functionally identical elements are provided with the same reference symbols.

[0042] Fig. 1 shows a motor vehicle 1 according to an embodiment of the present invention. In the present exemplary embodiment, the motor vehicle 1 is embodied as a passenger car. The motor vehicle 1 comprises a driver assistance system 2. For example, the driver assistance system 2 can detect an object 3 located in the surroundings 4 of the motor vehicle 1. In particular, the distance between the motor vehicle 1 and the object 3 can be determined using the driver assistance system 2.

[0043] The driver assistance system 2 comprises at least one ultrasonic sensor device 5. The ultrasonic sensor device 5, in turn, has at least one ultrasonic sensor 5a, 5b. The ultrasonic sensor 5a, 5b comprises a transmitting device 6, by means of which at least one ultrasonic signal 8, in particular a plurality of ultrasonic signals 8, can be emitted. In the present case, purely by way of example, an ultrasonic sensor device 5 with one ultrasonic sensor 5a, 5b is configured in a front region of the motor vehicle 1. Furthermore, purely by way of example, a further ultrasonic sensor device 5 is arranged in a rear region of the motor vehicle 1. The ultrasonic sensor device 5 in the rear region has, purely by way of example, four ultrasonic sensors 5a, 5b.

[0044] The transmitting device 6 can transmit the ultrasonic signals 8 within a predetermined detection range E or a predetermined angular range by means of a membrane. The membrane is coupled, in particular, to a sound transducer element 11, by means of which electrical signals can be converted into ultrasonic signals 8 during the transmission process and the echo signals 9 can be converted into electrical signals during the reception process. For example, the sound transducer element 11 can be a piezo element.

[0045] Furthermore, the ultrasonic sensor device 5 comprises a receiving device 7, by means of which reflected ultrasonic signals can be received as echo signals 9, which were reflected by the object 3, in particular via the membrane. The receiving device 7 can therefore receive ultrasonic signals 9 reflected by the object 3 as a received signal. Furthermore, the ultrasonic sensor device 5 can have a control device S, which can be formed, for example, by a microcontroller and / or a digital signal processor. The driver assistance system 2 further comprises a control device 10, which can be formed, for example, by an electronic control unit (ECU - electronic control unit) of the motor vehicle 1. The control device 10 is connected to the ultrasonic sensor device 5 for data transmission. The data transmission can take place, for example, via the data bus of the motor vehicle 1.

[0046] In the method for operating the ultrasonic sensor device 5 for the motor vehicle 1, a first ultrasonic sensor 5a' ( Fig. 2) the ultrasonic sensors 5a, 5b a first ultrasonic signal 8' ( Fig. 2) and by means of a second ultrasonic sensor 5a'' ( Fig. 2) the ultrasonic sensors 5a, 5b a second ultrasonic signal 8" ( Fig. 2) to determine a distance to the object 3 in the environment 4 of the motor vehicle 1. The two ultrasonic signals 8', 8" of the ultrasonic sensors 5a', 5a'' are transmitted with an identical frequency characteristic, whereby the first ultrasonic sensor 5a' is provided with a first control signal C1 ( Fig. 2) and the second ultrasonic sensor 5a'' with a second control signal C2 ( Fig. 2) can be controlled.

[0047] It is provided that the first control signal C1 is generated in such a way that the first control signal C1 has at least a first excitation phase A1 ( Fig. 3) for generating the first ultrasonic signal 8', and the second control signal C2 is generated such that the second control signal C2 has at least one second excitation phase A2 ( Fig. 3) for generating the second ultrasonic signal 8". The two control signals C1, C2 are generated in such a way that a first temporal start B1 ( Fig. 3) the first excitation phase A1 is offset in time from a second temporal beginning B2 ( Fig. 3) of the second excitation phase A2 and the first excitation phase A1 and the second excitation phase A2 overlap at least partially in time. Temporarily offset means that there is a time offset V ( Fig. 3) occurs.

[0048] In particular, it can be provided that in a respective echo signal 9 reflected by the object 3, which is received by at least the receiving device 7 of the ultrasonic sensor device 5, the respective excitation phase A1, A2 is identified and, based on the identification by means of the control device S of the ultrasonic sensor device 5, the respective received echo signal 9 is assigned to the respective ultrasonic sensor 5a', 5a'' and the respective distance to the object 3 is determined.

[0049] Furthermore, it can be provided that a respective random value for the time offset V between the first start B1 and the second start B2 is generated by means of the control device S.

[0050] In particular, the temporal offset V can be generated for a plurality of temporal offsets V such that the plurality of temporal offsets V has, for example, a predetermined mean value, which is in particular in the millisecond range. It can also be provided that the temporal offset V is generated such that it is within a predetermined time interval, in particular in the millisecond range.

[0051] Fig. 2 shows a schematic plan view of another embodiment of an ultrasonic sensor device 5. In the present exemplary embodiment, the ultrasonic sensor device 5 is arranged in particular in a front region of the motor vehicle 1. The ultrasonic sensor device 5 has six ultrasonic sensors 5a, 5b. In particular, in the following exemplary embodiment, the ultrasonic sensor device 5 has the first ultrasonic sensor 5a', the second ultrasonic sensor 5a'', and a further ultrasonic sensor 5a'''. The ultrasonic sensor device 5 further has three third ultrasonic sensors 5b, which are not described in detail here.

[0052] In the Fig. In the embodiment shown in Figure 2, the second ultrasonic sensor 5a'' transmits the ultrasonic signal 8'' as an ultrasonic signal 8 to an object 3'. The object 3' in turn reflects the ultrasonic signal 8 to form an inter-reflected ultrasonic signal 12, which in turn strikes a second object 3''. This in turn reflects the inter-reflected ultrasonic signal 12 to form the echo signal 9, which can be received by the first ultrasonic sensor 5a'. This example shows how so-called crosstalk can occur, even though the two ultrasonic sensors 5a' and 5a'' each have different sub-areas E1, E2 of the detection area E.

[0053] In this embodiment, it is provided that the first ultrasonic signal 8' and the second ultrasonic signal 8'' are formed, for example, as a frequency-modulated ultrasonic signal 8', 8'' that is modulated. In other words, the first ultrasonic signal 8' and the second ultrasonic signal 8'' can be a positive frequency chirp.

[0054] The further ultrasonic sensor 5a''' can emit a further ultrasonic signal 8''' during the same time step of the measuring cycle, since it is possible, for example, for the further ultrasonic sensor 5a''' to emit the further ultrasonic signal 8''', which in particular can have a different frequency curve than the first ultrasonic signal 8' and the second ultrasonic signal 8''. In particular, in the present exemplary embodiment, the further ultrasonic signal 8''' is designed as an ultrasonic signal 8 with a frequency-modulated frequency curve which is modulated. In other words, in the present exemplary embodiment, the further ultrasonic signal 8''' is designed as a negative frequency chirp. In other words, three ultrasonic sensors 5a', 5a'', 5a''' can emit a respective ultrasonic signal 8', 8'', 8''' simultaneously, at least in some areas.As a result, three ultrasonic sensors 5a', 5a'', 5a''' can perform a distance measurement within one time step of the measurement cycle. Due to the different frequency responses and the temporal offset V, an exact assignment of the respective echo signals 9 is nevertheless possible, so that a measurement cycle of the ultrasonic sensor device 5 can be performed in a reduced time.

[0055] In particular, it is provided that the further ultrasonic sensor 5a''' is controlled with a further control signal C3.

[0056] The Fig. The example shown in Figure 2 shows, in particular, a first time step of an entire measurement cycle of the ultrasonic sensor device 5, consisting in this embodiment of two time steps. In a second time step of the measurement cycle of the ultrasonic sensor device 5, the third ultrasonic sensors 5b would be analogous to Fig. 2. In other words, two third ultrasonic sensors 5b would be controlled with the same frequency response, and each additional one of the third ultrasonic sensors 5b would be controlled with a frequency response different from the frequency response of the first two of the third ultrasonic sensors 5b.

[0057] In other words, the excitation phases A1, A2 of the first control signal C1 and the second control signal C2 do not overlap in time with an excitation phase of a third control signal for the third ultrasonic sensor 5b. The beginning of the third control signal is thus temporally after an end time t2 ( Fig. 3) of the first and second control signals C1, C2. This allows for improved scanning of the environment 4 of the ultrasonic sensor device 5.

[0058] In particular, Fig. 2, that the first ultrasonic signal 8' of the first ultrasonic sensor 5a' is emitted into the first sub-area E1 of the environment 4, and the second ultrasonic signal 8'' is emitted into the second sub-area E2, which differs from the first sub-area E1. In particular, the two sub-areas E1 and E2 are formed at least partially opposite one another. In particular, the further ultrasonic signal 8''' is emitted into a further sub-area E3 of the environment 4, which differs at least partially from the first sub-area E1 and the second sub-area E3.

[0059] Fig. 3 shows a schematic diagram of the operation of the ultrasonic sensor device 5. The Fig. Figure 3 shows the time course of the control signals C1, C2, C3. The rising line of the first control signal C1 indicates that this signal is a positive frequency chirp. The same applies to the second control signal C2. The falling line of the further ultrasonic sensor 5a''' indicates the further control signal C3, which in this case is designed as a negative frequency chirp. In other words, Fig. 3 shows a time profile of the first time step of the measurement cycle. In particular, the ultrasonic sensors 5a', 5a'', and 5a''' are subjected to the control signals C1, C2, C3 at time t0. In particular, the first control signal C1 has the first excitation phase A1, the second control signal C2 has the second excitation phase A2, and the further control signal C3 has a further excitation phase A3. In particular, the second ultrasonic sensor 5a'' is excited later in time than the first ultrasonic sensor 5a' and in particular than the further ultrasonic sensor 5a''' due to the time offset V.

[0060] In particular, it is provided that the temporal offset V is generated such that an average value of a time period t of a plurality of temporal offsets V is three milliseconds. Furthermore, it can be provided that the temporal offset V is generated such that the temporal offset V lies in a time range between one millisecond and eight milliseconds.

[0061] Furthermore, it can be provided that, in order to generate the respective ultrasonic signal 8', 8'', 8''' of the respective ultrasonic sensor 5a', 5a'', 5a''' during the respective excitation phase A1, A2, A3, the respective ultrasonic sensor 5a', 5a'', 5a''' is excited with a respective excitation signal whose respective frequency response is frequency-modulated. In particular, the respective frequency-modulated frequency response is modulated and configured as a positive frequency chirp. Furthermore, it can be provided that the respective frequency-modulated frequency response is modulated and configured as a negative frequency chirp.

[0062] In particular, the further ultrasonic sensor 5a''' has a further start B3, wherein the first start B1 and the further start B3 are temporally the same, but different from the second start B2.

[0063] In particular, it is intended that at time t0, as in Fig.3, the first ultrasonic sensor 5a' and the further ultrasonic sensor 5a''' are excited. In particular, the ultrasonic sensors 5a' and 5a''' have different frequency characteristics, which is why they can be excited simultaneously at time t0. The second ultrasonic sensor 5a'' is excited at time t1. Between time t0 and t1, the time offset V has occurred. In particular, the second ultrasonic signal 8'' is frequency-modulated to the same extent as the first ultrasonic signal 8'. It is intended that the excitation phases A1 and A2 overlap at least partially in time.

[0064] In particular, the first start B1 and the further start B3 are at time t0. In particular, the second start B2 is offset in time from time t1. The time t2 describes in particular end times of the first and the further excitation phase A1, A3. The time t3 describes the end time of the second excitation phase A2. In particular, it is provided that the respective excitation phases A1, A2, A3 are designed to be the same in time. In particular, in the present exemplary embodiment, a receive phase for receiving the echo signal 9 of the second ultrasonic sensor 5a'' is shortened compared to the receive phases of the first ultrasonic sensor 5a' and the further ultrasonic sensor 5a''', so that at an end time t4 the ultrasonic sensors 5a', 5a'', 5a''' end the receive phase simultaneously.In other words, the reception phases of the first ultrasonic sensor 5a' and the further ultrasonic sensor 5a''' begin at time t2, and the reception phase of the second ultrasonic sensor 5a'' begins at time t3. In particular, the reception phases of the first ultrasonic sensor 5a' and the further ultrasonic sensor 5a''' then have a first time duration t2-t4, while the reception phase of the second ultrasonic sensor 5a'' has a second time duration t3-t4, which is different from, and in particular shortened to, the first time duration t2-t4.

[0065] Furthermore, it can be provided, in particular, that the first ultrasonic sensor 5a' is excited during the first excitation phase A1 and the second ultrasonic sensor 5a'' is excited at different times during the second excitation phase A2. For this purpose, the first excitation phase A1 has a different first time period t0 to t2, in particular a longer time period t0 to t2, than a second time period t1 to t2 of the second excitation phase A2, so that at least one end time t2 of the two excitation phases A1, A2 is temporally identical.

[0066] In particular, it can be provided that the first time step of the measuring cycle is directly followed by the second time step of the measuring cycle.

Claims

[1] A method for operating an ultrasonic sensor device (5) for a motor vehicle (1), which has at least one first ultrasonic sensor (5a') and at least one second ultrasonic sensor (5a''), wherein a first ultrasonic sound signal (8') is emitted by means of the first ultrasonic sensor (5a') and a second ultrasonic sound signal (8'') is emitted by means of the second ultrasonic sensor (5a'') to determine a distance of an object (3', 3'') in an environment (4) of the motor vehicle (1) into the environment (4), wherein the ultrasonic signals (8', 8'') of the ultrasonic sensors (5a', 5a'') are emitted with an identical frequency characteristic, wherein for this purpose the first ultrasonic sensor (5a') is controlled with a first control signal (C1) and the second ultrasonic sensor (5a'') is controlled with a second control signal (C2), characterized bythat the first control signal (C1) is generated such that the first control signal (C1) has at least a first excitation phase (A1) for generating the first ultrasonic signal (8'), and the second control signal (C2) is generated such that the second control signal (C2) has at least a second excitation phase (A2) for generating the second ultrasonic signal (8''), wherein the two control signals (C1, C2) are generated such that a first temporal start (B1) of the first excitation phase (A1) is offset in time from a second temporal start (B2) of the second excitation phase (A2) and the first excitation phase (A1) and the second excitation phase (A2) at least partially overlap in time. [2] Method according to claim 1, characterized byin that in a respective echo signal (9) reflected by the object (3', 3''), which is received by at least one receiving device (7) of the ultrasonic sensor device (5), the respective excitation phase (A1, A2) is identified and, on the basis of the identification by means of a control device (S) of the ultrasonic sensor device (5), the respective received echo signal (9) is assigned to the respective ultrasonic sensor (5a', 5a'') and the respective distance to the object (3', 3'') is determined. [3] Method according to claim 1 or 2, characterized by that a respective random value for the time offset (V) between the first start (B1) and the second start (B2) is generated by means of a control device (S). [4] Method according to claim 3, characterized by that the time offset (V) is generated such that an average value of a time period (t) of a plurality of time offsets (V) is 3 ms. [5] Method according to claim 3 or 4, characterized by that the time offset (V) is generated in such a way that the time offset (V) lies in a time range between 1 ms and 8 ms. [6] Method according to one of the preceding claims, characterized by in that, in order to generate the respective ultrasonic signal (8', 8'') of the respective ultrasonic sensor (5a', 5a'') during the respective excitation phase (A1, A2), the respective ultrasonic sensor (5a', 5a'') is excited with the respective control signal (C1, C2), the respective frequency curve of which is frequency-modulated at least in some areas. [7] Method according to claim 6, characterized by that the respective frequency-modulated frequency response is modulated. [8] Method according to claim 6, characterized by that the respective frequency-modulated frequency response is modulated. [9] Method according to one of the preceding claims, characterized byin that the ultrasonic sensor device (5) has at least one third ultrasonic sensor (5b), wherein within a measuring cycle of the ultrasonic sensor device (5) a third control signal for generating a third ultrasonic signal is generated by the third ultrasonic sensor (5b) at a time offset from the first control signal (C1) and the second control signal (C2) by means of a control device (S). [10] Method according to one of the preceding claims, characterized byin that the ultrasonic sensor device (5) has at least one further ultrasonic sensor (5a'''), wherein a further control signal (C3) for generating a further ultrasonic signal (8''') is generated by means of the ultrasonic sensor device (5), wherein the further ultrasonic signal (8''') has a different frequency curve than the frequency curves of the first ultrasonic signal (8') and the second ultrasonic signal (8''), wherein the respective excitation phases (A1, A2, A3) of the three ultrasonic sensors (5a', 5a'', 5a''') at least partially overlap in time. [11] Method according to one of the preceding claims, characterized by that the first ultrasonic signal (8') of the first ultrasonic sensor (5a') is emitted into a first partial area (E1) of the environment (4) and the second ultrasonic signal (8'') is emitted into a second partial area (E2) of the environment (4) which is different from the first partial area (E1). [12] Method according to one of the preceding claims, characterized by in that the first ultrasonic sensor (5a') is excited during the first excitation phase (A1) and the second ultrasonic sensor (5a'') is excited at different times during the second excitation phase (A2), wherein a first receiving phase for receiving an echo signal (9) of the first ultrasonic sensor (5a') has a different first time duration (t2-t4), in particular a longer time duration (t2-t4), than a second time duration (t3-t4) of a second receiving phase for receiving an echo signal (9) of the second ultrasonic sensor (5a''), so that at least one end time (t4) of the two receiving phases is the same in time. [13] Ultrasonic sensor device (5) with at least one first ultrasonic sensor (5a'), at least one second ultrasonic sensor (5a'') and with at least one control device (S), wherein the ultrasonic sensor device (5) is designed to carry out a method according to one of claims 1 to 12. [14] Motor vehicle (1) with an ultrasonic sensor device (5) according to claim 13.

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