Ultrasonic sensor device for a vehicle and operation thereof

Abstract

The problem addressed by the invention is that of increasing the range of object recognition in the surround of a vehicle (1) by means of ultrasound. An ultrasonic sensor device (3) comprising two ultrasonic sensors (4, 5) and a controller (8) is provided to this end. The controller controls the ultrasonic sensors (4, 5) to transmit a respective ultrasonic signal (4a, 5a) with appropriately assigned signal parameters. When installed in the vehicle (1), the ultrasonic sensors (4, 5) are arranged next to one another with a predetermined distance (d) between them. When the ultrasonic signals (4a, 5a) are transmitted, the signals superimpose in a superposition region (6), which is specified by the distance (d), in order to form a superposition signal. The superposition signal (6a) is amplified in comparison with the first and at least second ultrasonic signal (4a, 5a) by a gain value specified by the signal parameters of the latter signals. To increase the range, signal amplification, in particular amplitude amplification, is thus brought about by superposition of the ultrasonic signals (4a, 5a).

Description

[0001] Ultrasonic sensor device for a vehicle and its operation

[0002] The invention relates to an ultrasonic sensor device for a vehicle. Furthermore, the invention relates to a vehicle having a corresponding ultrasonic sensor device. The invention also relates to a method for operating a corresponding ultrasonic sensor device for a vehicle.

[0003] Some vehicles are equipped with driver assistance systems designed to alert the driver to objects or obstacles in the surrounding area. In addition to the position of the object relative to the vehicle and its distance, the object's geometry can be determined, for example. To do this, the driver assistance system uses environment sensors suitable for the respective application, with which the object can be recognized or detected in the surrounding area. For object detection in close range, i.e., within a range of a few centimeters or a few meters, ultrasonic sensors, for example, are used. These are widely used in vehicles as parking sensors for parking assistance or collision sensors for collision protection when opening vehicle doors.

[0004] Object detection using an ultrasonic sensor is based on well-known measuring principles. For example, a sound transducer in the ultrasonic sensor is stimulated to emit an ultrasonic pulse or an ultrasonic signal. If there is an object in the surrounding area, the object can reflect this pulse and send it back as an echo to the sound transducer or another sound transducer in an ultrasonic sensor. The respective sound transducer can receive the echo, and evaluation electronics can evaluate the echo signal using well-known evaluation methods. For example, the distance of the object relative to the vehicle can be determined based on a time-of-flight measurement between the originally emitted ultrasonic pulse and the echo. If several spatially distributed ultrasonic sensors are used, or if the object is moving, its position can be deduced using triangulation, for example.Various possibilities for generating and evaluating ultrasound signals are known from the state of the art.

[0005] For example, WO 2015 / 124190 A1 discloses a method for determining the position of an object using ultrasonic signals. Two different ultrasonic signals are modulated with different modulation signals, and then a sum signal composed of a superposition of the ultrasonic signals reflected from the object is received. The position of the object can be determined based on the ratio of the signal amplitudes of the different modulation signals in the sum signal.

[0006] US 7,196,970 B2 discloses a method for measuring the distance to an object using ultrasound. An ultrasonic generator generates and transmits an ultrasonic signal with two superimposed frequencies. An echo pulse, which is reflected back from an object when the ultrasonic signal is reflected, is used to determine the distance to the object based on time-of-flight differences.

[0007] JP 4750817 B2 discloses a method for determining the position and distance of a stylus used for input, for example, on a tablet. For this purpose, several ultrasonic signal generators are stacked one above the other in a housing of the stylus and controlled to jointly output ultrasonic signals, which are then superimposed and amplified.

[0008] In vehicle applications, ultrasonic sensors for object detection can currently only be used at close range, i.e. at a distance of 5 m or less from the vehicle. The reason for this is that the emitted ultrasonic signal is increasingly attenuated as the propagation time increases due to air friction. This can result in the echo received by the respective ultrasonic sensor being so weak that meaningful analysis is no longer possible. Therefore, when detecting objects using ultrasound, care is taken to provide a signal amplitude that is as constant as possible across the entire detection range so that even objects that are further away from the vehicle can be reliably detected. One option for this is to amplify the emitted ultrasonic signal. The disadvantage of this type of signal amplification is that it also amplified ambient noise, such as background and interference reflections.This leads to a signal-to-noise ratio deteriorating with increasing signal propagation time.

[0009] It is the object of the present invention to increase the range for object detection by means of ultrasound without introducing disruptive effects in the signal transmission.

[0010] The problem is solved by the subject matter of the independent patent claims. The dependent patent claims, as well as the description and the figures, disclose advantageous developments of the invention.

[0011] The invention is based on the finding that the signal amplification required to increase the range can be achieved by operating two or more adjacent ultrasonic sensors together for signal generation or signal transmission. Signal amplification is achieved by superimposing the generated signals and amplifying them, particularly through positive interference. By superimposing the signals, a doubling of the signal amplitude can be achieved. However, the superimposed signal is no more susceptible to interference, such as reflections in the environment, than the individually transmitted signals. This allows a better signal-to-noise ratio to be achieved even at greater ranges from the vehicle, and signal interference can be successfully compensated.

[0012] To this end, according to one aspect, the invention proposes an ultrasonic sensor device for a vehicle. The ultrasonic sensor device comprises a first ultrasonic sensor and at least one second ultrasonic sensor, as well as at least one control device. The control device is designed to control the first ultrasonic sensor to emit a first ultrasonic signal with first signal parameters. Furthermore, the control device is designed to control the at least second ultrasonic sensor to emit a second ultrasonic signal with second signal parameters. The control device controls the ultrasonic sensors in particular such that the ultrasonic signals are emitted together in time, at least in certain regions. For example, the signals can be emitted simultaneously or with a time delay relative to one another.In a predetermined installation position, i.e. a predetermined installation position or installation location in the vehicle, the first and the at least second ultrasonic sensor are arranged or mounted next to one another at a predetermined distance. This means that the at least two ultrasonic sensors are attached to the vehicle adjacent to one another in a common radiation direction. When the respective ultrasonic signal is emitted by the respective ultrasonic sensor, the first and the at least second ultrasonic signal overlap to form a superposition signal in an overlap region predetermined by or dependent on the distance. In other words, the distance for the ultrasonic sensors is preferably selected or predetermined such that the ultrasonic signals overlap in some areas in the surrounding area, in particular depending on their signal characteristics.

[0013] The resulting beat signal is amplified compared to the first and at least the second ultrasonic signal by a gain value or factor predetermined by, and therefore dependent on, their signal parameters. In other words, the signal parameters are selected or adjusted, for example by means of the control device, such that the signals are amplified when superimposed. This occurs through superposition of the wavefronts of the ultrasonic signals, resulting in the beat signal. The superposition preferably occurs through constructive interference of the sound waves. In this way, an amplitude increase for the beat signal can be achieved. The gain value, i.e. the extent to which the amplitude is increased, depends in particular on the intersection point of the wavefronts, i.e. the sum of the superimposed amplitude values ​​of the individual ultrasonic signals.Thus, the superimposed signal has a signal amplitude that results from the sum of the amplitude values ​​of the individual ultrasonic signals. Preferably, the signal parameters and the spacing are selected to achieve a maximum amplitude increase for the ultrasonic signals.

[0014] The described ultrasonic sensor device has the advantage that the signal range for object detection in close range can be increased from the current 5 m by several meters, in particular up to 8 m or 10 m. The signal amplification is achieved depending on the distance between the ultrasonic sensors and the selected signal parameters. The resulting overlay signal is less influenced by ambient noise due to the subsequent amplification. Furthermore, the device can be used to improve detection accuracy close to the sensors, for example, at distances of less than 2 m, since the resulting echo or echo signal, which arises when the overlay signal is reflected off a potential object in the surrounding area, is also amplified.

[0015] To generate the respective ultrasonic signal, each of the ultrasonic sensors can have one or more ultrasonic transducers. With an ultrasonic transducer, a high-frequency electrical control signal can be converted into a mechanical vibration using the piezoelectric effect. For this purpose, the sound transducer comprises, for example, one or more piezoelectric components, such as a piezoceramic. The piezoelectric component can be coupled to a membrane in a sound-conductive manner. This allows the piezoelectric component to transmit the resulting mechanical vibration to the membrane when excited. The surrounding air can be set into vibration via the membrane in such a way that the desired ultrasonic signal is generated. The ultrasonic signals can be output as a so-called burst or signal pulse. As an alternative to a single signal pulse, it is possible to provide multiple signal pulses at different times or one after the other.

[0016] The electrical control signal can be generated and provided by the control device. It is preferably an alternating electrical voltage. The frequency of the control signal corresponds in particular to the frequency at which the piezoelectric component is deflected, i.e., oscillates. The transmission frequency of the respective ultrasonic signal can thus be adjusted depending on the frequency of the control signal. The amplitude of the ultrasonic signal depends in particular on the properties of the piezoelectric component used.

[0017] The described sound conversion effect is particularly reversible or reciprocal. When ultrasonic signals are received, the air vibration causes the membrane, which in turn causes the piezoelectric component to vibrate mechanically. Using the piezoelectric effect, the mechanical vibration is converted into an electrical received signal, which can be tapped off in particular as an alternating voltage. The control device can detect and evaluate this received signal in order to obtain the desired information about the object. Exemplary embodiments of how the evaluation can be carried out are described in more detail later. Due to reciprocity, any ultrasonic sensor can in principle be used as a transmitter and / or receiver of ultrasonic signals. When used together for transmitting and receiving, the ultrasonic sensor is also referred to as a transceiver.If the ultrasonic sensors of the ultrasonic sensor device are designed as transceivers, switching between a transmit and receive mode is possible. This means that transmission and reception occur with each ultrasonic sensor separately or sequentially. For this purpose, the control device operates the respective ultrasonic sensor in a time-division multiplexing process, either in the transmit mode or in the receive mode. When designed separately as a transmitter or receiver, the present ultrasonic sensor device can, in addition to the at least two ultrasonic sensors, which are operated here as transmitters, additionally have one or more further ultrasonic sensors that are operated as receivers.

[0018] In the present invention, the two or more ultrasonic sensors are arranged next to one another. The term "next to one another" refers to a common radiation direction or main beam direction in which the ultrasonic signals are emitted by the ultrasonic sensors in their installation position in the vehicle. The ultrasonic transducers are mounted adjacent to the vehicle or its body components perpendicular to the main beam direction. In the present case and below, the main beam direction refers in particular to the direction in which the signal strength of the respective signal is maximum. The main beam direction is predetermined in particular by the radiation characteristics of the ultrasonic sensors. Depending on the installation position in the vehicle, the main beam direction can, for example, run in the direction of a longitudinal axis or transverse axis of the vehicle.This means that the main beam direction can be in front of, behind or to the side of the vehicle in the direction of travel, depending on the installation position.

[0019] The choice of distance and / or the dimensioning of the overlap area depends particularly on the signal characteristics of the respective ultrasonic sensor. The signal characteristics, which can also be referred to as directional characteristics, refer to the angular or directional dependence of the strength of received or transmitted signals. In particular, the signal characteristics can be adjusted using signal parameters, such as a transmission frequency. The signal characteristics are specified, for example, by a manufacturer or distributor of the respective sensor. The distance and / or the overlap area can be determined, for example, through simulations or in test experiments for the selected installation position.

[0020] The control device can, for example, be designed as an electronic control unit (ECU). The control device can, for example, have at least one microprocessor and / or at least one microcontroller and / or at least one FPGA (Field Programmable Gate Array) and / or at least one DSP (Digital Signal Processor). Furthermore, the control device can, for example, have one or more ASICs (Application Specific Integrated Circuits) as drivers for the ultrasonic sensors. An ASIC can, for example, be implemented as an integrated circuit. The ECU can control the ASIC for operation, i.e., for example, to output the control signal for ultrasound generation.

[0021] The invention includes embodiments which provide additional advantages.

[0022] According to one embodiment, the control device is configured to specify a transmission frequency and / or a signal transmission time as respective signal parameters for the first and at least second ultrasonic signals. The transmission frequency specifies which frequency or frequencies the respective ultrasonic signal contains. The signal transmission time specifies the start time or beginning of transmission of the ultrasonic signal. This means that the control device can schedule the time at which the ultrasonic signals are transmitted.

[0023] By selecting the appropriate transmission frequencies and signal transmission times, it can be ensured that the wavefronts of the ultrasonic signals overlap in the overlapping area at the desired location or position in space, thus achieving the desired amplification value. Preferably, the transmission frequency and signal transmission time are coordinated in such a way that the desired amplification value for the superimposed signal can be achieved. The transmission frequency or signal transmission time can thus be used to set or control the desired signal amplification. The ultrasonic signals can, for example, have similar or different transmission frequencies. Additionally or alternatively, the transmission start time can be set simultaneously, or it can begin sequentially or with a delay. Another adjustable signal parameter can be, for example, the amplitude of the respective ultrasonic signal.

[0024] According to one embodiment, the control device is configured to modify or adapt the transmission frequency and the signal transmission time for the first and at least the second ultrasonic signal according to a predetermined first modification criterion such that the superimposed signal has a main beam direction perpendicular to a central axis between the ultrasonic sensors. Thus, the superimposed signal can be transmitted straight ahead relative to the central axis in the installed position.

[0025] According to one embodiment, the control device is configured to modify or adapt the transmission frequency and the signal transmission time for the first and at least the second ultrasonic signal according to a predetermined second modification criterion such that the superimposed signal has a main beam direction oblique to a central axis between the ultrasonic sensors. Thus, the superimposed signal can be transmitted obliquely relative to the central axis in the installed position, i.e., in a desired direction or at a desired angle.

[0026] In the described embodiments, the aim is to specify a direction for the overlay signal. The overlay signal is to be transmitted in a directed manner. The signal strength of the overlay signal is thus maximized in the desired direction (main beam direction). This is achieved by appropriately synchronizing the transmission pulses, i.e., the ultrasonic signals. The appropriate settings for the ultrasonic signals to achieve this desired synchronization are specified by the respective modification criterion. For example, the respective modification criterion can specify values ​​for the transmission frequency and / or the signal transmission time depending on the desired main beam direction. The selection of the values ​​can be made depending on the known distance and the installation position.For each desired direction in which the overlay signal is to be transmitted, the values ​​for the transmission frequency and / or the signal transmission time can be stored, for example, in a characteristic map or a function depending on the distance and / or the installation position. The control unit can retrieve these values ​​from the characteristic map or determine them from the function. The central axis refers in particular to an axis that runs centrally between the adjacent sensors in the respective installation position. The central axis typically runs parallel to or in the direction of the main beam direction of the transmitted ultrasonic signals.

[0027] According to one embodiment, the control device is configured to control the first and at least the second ultrasonic sensor to provide the overlay signal in at least two different main beam directions relative to, in particular perpendicular or oblique to, the central axis. This means that in one transmission process, it is possible to change the signal direction of the overlay signal twice or multiple times. Thus, as is known, for example, from laser scanners, several different sections in the environment around the vehicle can be scanned or detected.

[0028] According to one embodiment, the control device is designed to select the respective main beam direction depending on an expectation range in which an object in the environment is expected depending on a previously known movement maneuver of the vehicle. This means that only those areas or sections of the environment in which an object is potentially located need to be scanned. The movement maneuver of the vehicle specifies the possible direction or position of the object relative to the vehicle. The movement maneuver can be a driving maneuver, for example. The driving maneuver can be specified, for example, by a steering angle and / or the direction of travel of the vehicle. For example, when parking sideways, a section in the area of ​​a vehicle's side and rear can be specified as the expectation range.Alternatively or additionally, the movement maneuver can, for example, be a component movement of a vehicle component. The component movement can, for example, be the actuation of a vehicle door or tailgate to open or close it. The expected area can thus be the area in which the door or tailgate to be actuated is located.

[0029] According to one embodiment, the first ultrasonic signal has, as a signal parameter, a transmission frequency with a first frequency value. The second ultrasonic signal has, as a signal parameter, a transmission frequency with a different second frequency value. This means that the ultrasonic signals are output as a pulse or "burst" with a constant frequency. Preferably, the respective transmission frequency is formed only from the first frequency value or only from the second frequency value.

[0030] According to one embodiment, the first ultrasonic signal has a transmission frequency with a first frequency spectrum as a signal parameter. The second ultrasonic signal has a transmission frequency with a different second frequency spectrum as a signal parameter. The frequency spectra preferably have different center frequencies or average frequencies. The frequency values ​​contained in the first and second frequency spectra are in ascending or descending order. The ultrasonic transducers can output the respective ultrasonic signal as a frequency sweep of the associated frequency spectrum, for example, from the highest frequency to the lowest frequency or vice versa. This type of output is also referred to as "chirp." The ultrasonic signals are preferably output with a frequency sweep in a different order.

[0031] According to one embodiment, the first and / or at least the second ultrasonic sensor are configured to emit and / or preferably receive ultrasonic signals with a transmission frequency in the range of 47 to 52 kHz. This means that the ultrasonic transducers, in particular their components, can be optimally designed for this frequency range. Thus, the maximum signal strength can be transmitted or received in this frequency range.

[0032] According to one embodiment, the first and / or at least the second ultrasonic sensor are configured to receive an echo signal as a reflected first and / or second ultrasonic signal and / or as a reflected superposition signal from an object in the environment. The ultrasonic sensor device further comprises an evaluation unit configured to evaluate the echo signal according to a predetermined evaluation principle to determine a distance and / or a position and / or a geometry of the object relative to the ultrasonic sensor device.

[0033] As described above, the ultrasonic sensors can therefore also be designed to receive ultrasonic signals. The evaluation device can, for example, be included in the control device or be designed as a separate unit analogous to the control device. For the evaluation, the evaluation device can detect or receive the echo signal received by the respective ultrasonic transducer and converted into an electrical signal or received signal. The evaluation is carried out according to known evaluation principles, as are sufficiently known from the prior art. To determine the distance, for example, time differences between the transmitted signals and the echo signal can be determined. The location or position of the object can be determined, for example, using triangulation. By determining the geometry, the height of the object can be detected, for example.This makes it possible, for example, to decide whether the object, such as a curb, can be driven over by the vehicle or not.

[0034] If the overlay signal is transmitted in a directed manner, as described above, the advantage is that two signal paths of the echo signal from the object back to the respective ultrasonic sensor are sufficient to determine the direction sufficiently. Without a specified direction, however, at least four signal paths are required to perform the triangulation accurately. To determine the direction for the signal reception of the resulting echo, it is possible to filter the received signal in a suitable manner so that only echoes from this direction are considered for processing. For this purpose, the evaluation device can comprise, for example, a suitable signal filter or a filter circuit.

[0035] According to one aspect, the invention relates to a vehicle with at least one ultrasonic sensor device, as described above by way of example. The vehicle preferably comprises several, i.e., two or more, of the aforementioned ultrasonic sensor devices. The vehicle is preferably configured as a motor vehicle, in particular as a passenger car, truck, passenger bus, or motorcycle.

[0036] The respective ultrasonic sensor device can, for example, be part of a driver assistance system for the vehicle. The driver assistance system can, for example, be a parking aid, a parking assistant, or a collision protection assistant. Using the driver assistance system, the driver can, for example, be automatically assisted when parking or protected from collisions. For this purpose, the driver assistance system can acoustically or visually indicate or output to the driver the distance, position, or geometry of the object determined by the ultrasonic sensor device. Additionally or alternatively, the driver assistance system can, for example, intervene in the control or steering of the vehicle depending on the object detection carried out with the ultrasonic sensor device.

[0037] According to one embodiment, the at least two or more ultrasonic sensors of the at least one ultrasonic sensor device are mounted in the vehicle's installation position in a vehicle door, a tailgate, or a bumper. This means that the ultrasonic sensors are attached to the respective vehicle part or integrated into its structure.

[0038] According to one aspect, the invention relates to a method for operating an ultrasonic sensor device for a vehicle. The ultrasonic sensor device is preferably an ultrasonic sensor device as described above by way of example. Operating the ultrasonic sensor device in this case particularly comprises transmitting ultrasonic signals. However, operation can also include receiving ultrasonic signals, as described above by way of example. The method can be carried out using the control device of the ultrasonic sensor device.

[0039] The ultrasonic sensor device comprises a first ultrasonic sensor and at least one second ultrasonic sensor, as well as at least one control device. This control device controls the first ultrasonic sensor to emit a first ultrasonic signal with first signal parameters. Furthermore, the control device controls the at least second ultrasonic sensor to emit a second ultrasonic signal with second signal parameters.

[0040] The first and at least the second ultrasonic sensor are arranged next to one another in a predetermined installation position in the vehicle at a predetermined distance. This results in the first and at least the second ultrasonic signal being superimposed to form a superposition signal within an overlap range predetermined by the distance. Compared to the first and at least the second ultrasonic signal, the superposition signal is amplified by a gain value predetermined by their signal parameters. To achieve the desired superposition and amplification of the ultrasonic signals, the control device can, for example, predetermine or select the appropriate signal parameters for the ultrasonic signals in the manner described above.

[0041] The described method can describe an amplification mode in which the ultrasonic sensor device can be operated by means of the control device. The amplification mode can preferably be activated or deactivated, i.e., switched on or off, as needed. For example, the amplification mode can be switched on if a very close object has been detected and near-object detection is to be improved. Alternatively or additionally, it is possible to activate the amplification mode if, for example, no object has been detected in the close range, as can be achieved with existing ultrasonic sensors, and the detection range or the detection radius of the ultrasonic sensor device is to be expanded by amplifying it.

[0042] As an alternative to the amplification mode, the ultrasonic sensor device can be operated, for example, in a normal mode by means of the control device. In the normal mode, for example, only one of the two ultrasonic sensors is active, or the signal parameters are preferably set such that the ultrasonic signals do not overlap and thus amplify. Preferably, the signal range of the ultrasonic signals, in particular of the superimposed signal, is increased in the amplification mode compared to the normal mode.

[0043] For applications or application situations that may arise in a method according to the invention and are not explicitly described herein, it may be provided that, according to the method, an error message and / or a request to enter user feedback is output and / or a standard setting or a predetermined initial state is set.

[0044] Embodiments of the method according to the invention and of the vehicle according to the invention follow directly from the various embodiments of the ultrasonic sensor device according to the invention, and vice versa. In particular, individual features and a corresponding explanation as well as advantages of the various embodiments of the ultrasonic device according to the invention can also be transferred analogously to corresponding embodiments of the vehicle according to the invention and of the method according to the invention. In particular, the ultrasonic device according to the invention is designed or programmed to carry out a method according to the invention. In particular, the ultrasonic sensor device according to the invention carries out a method according to the invention.

[0045] 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 in the figures can be encompassed by the invention not only in the respectively specified combination, but also in other combinations. In particular, the invention can also encompass embodiments and combinations of features that do not have all the features of an originally formulated claim. Furthermore, the invention can encompass embodiments and combinations of features that go beyond the combinations of features set out in the backreferences to the claims or deviate from them.

[0046] The invention is explained in more detail below using specific embodiments and associated schematic drawings. In the figures, identical or functionally equivalent elements may be provided with the same reference numerals. The description of identical or functionally equivalent elements may not necessarily be repeated for different figures.

[0047] The figures show:

[0048] Fig. 1 is a schematic representation of a vehicle with an ultrasonic sensor device for environmental detection,

[0049] Fig. 2 is a schematic representation of the ultrasonic sensor device in a first operating mode,

[0050] Fig. 3 is a schematic representation of the ultrasonic sensor device in a second operating mode, Fig. 4 is a schematic representation of a signal amplification of a superposition signal that can be generated by means of the ultrasonic sensor device, and

[0051] Fig. 5 is a schematic process flow diagram for operating an ultrasonic sensor device.

[0052] Fig. 1 shows a schematic representation of a vehicle 1. The vehicle is shown from a bird's-eye or top view. The vehicle 1 is preferably a passenger car. In Fig. 1, the vehicle 1 is shown in a specific driving situation, namely during a parking maneuver. In particular, the vehicle 1 is to park sideways into a parking space. To symbolize the parking maneuver, a driving path F is drawn in Fig. 1 with a dash-dotted line, which the vehicle 1 follows when performing the sideways parking maneuver.

[0053] As shown in Fig. 1, the parking space intended for vehicle 1 is bordered by another parked vehicle. The parked vehicle is an object 9 in the environment U, which represents an obstacle for vehicle 1. In order to assist a driver of vehicle 1 (not shown in Fig. 1) during the parking maneuver, vehicle 1 in the present case comprises, for example, a driver assistance system 2. This assistance particularly involves alerting the driver to a potential collision with object 9. Driver assistance system 2 is designed, for example, as a parking assistant. Driver assistance system 2 can automatically observe and record the environment U and react accordingly. In the present case, driver assistance system 2 is intended to warn the driver, for example, acoustically or visually, of object 9 as an obstacle during the parking maneuver.In particular, the distance to the object 9 and, for example, a position of the object 9 relative to the vehicle 1 should be detected and communicated to the driver.

[0054] For this purpose, the driver assistance system 2 is coupled to a device for detecting the environment, i.e., an environment sensor system. An ultrasonic sensor system is used as the environment sensor system. In the present case, the ultrasonic sensor system comprises a plurality of ultrasonic sensor devices 3, which are installed in a respective installation position in the vehicle 1. In the present case, three ultrasonic sensor devices are attached to the front of the vehicle, for example, on a bumper. Two ultrasonic sensor devices are attached to the rear of the vehicle, for example, on a tailgate of the vehicle 1. Furthermore, in the exemplary embodiment according to Fig. 1, an ultrasonic sensor device 3 is attached to each of the four vehicle doors of the vehicle 1.Each of the ultrasonic sensor devices is designed to detect or generate sensor data or sensor signals which image, represent or reproduce the environment U of the vehicle 1, in particular the objects 9 present in the detection area.

[0055] The aim is therefore to detect object 9 in the environment U. In this case, the environment is detected using ultrasonic signals. For this purpose, each of the ultrasonic sensor devices 3 comprises one or more ultrasonic sensors 4, 5. Each ultrasonic sensor 4, 5 is designed to emit an ultrasonic signal 4a, 5a to the environment U. If an object 9 is located in the environment U, the emitted ultrasonic signal 4a, 5a can be reflected thereon and thrown back to the ultrasonic sensor device 3. The reflected ultrasonic signal is also referred to below as an echo or echo signal. This echo can be detected by the same or any other ultrasonic sensor 4, 5 of one of the ultrasonic sensor devices 3 of the vehicle 1. By evaluating the detected echo signal, for example by means of a suitable control device or evaluation device, the object 9 in the environment U can be detected or identified.For example, the distance to object 9 can be determined in a known manner based on time-of-flight measurements between the emitted ultrasonic signal 4a, 5a and the echo signal. By triangulating one or more echo signals, which are detected, for example, by different ultrasonic sensors 4, 5, the location or relative position of object 9 to vehicle 1 can be deduced. Such evaluation methods for object detection 9 are well known per se.

[0056] Conventional ultrasonic sensor systems are designed for object detection in the near field or close range, which is typically up to a maximum of 5 m from the vehicle 1. Objects 9 further away, for example, in a range of up to 8 m or 10 m, cannot be detected or can only be detected with insufficient accuracy due to signal attenuation effects in the air. With reference to Figs. 2 and 3, an ultrasonic sensor device 3 will now be presented, with which the range of conventional ultrasonic sensor devices can be increased.

[0057] Fig. 2 shows an example of one of the ultrasonic sensor devices 3 according to Fig. 1 in a

[0058] Detailed view. The ultrasonic sensor device 3 in the present case comprises a control device 8 and, for example, two ultrasonic sensors, which can be referred to as first and second ultrasonic sensors 4, 5. Of course, the ultrasonic sensor device 3 can comprise more than two ultrasonic sensors 4, 5. The control device 8 is designed, for example, as an electronic control unit (ECU). The function of the control device 8 is to control the ultrasonic sensors 4, 5 to output the respective ultrasonic signal. For this purpose, the control device 8 can, for example, provide a suitable control signal, in particular an alternating voltage with a predetermined frequency, to each of the ultrasonic sensors 4, 5. An ultrasonic transducer, which the respective ultrasonic sensor 4, 5 comprises, can convert this electrical signal into a mechanical oscillation, which is converted, for example, by a membrane into an air oscillation.This air vibration can propagate into the environment as a sound wave. If the control frequency is selected appropriately, a sound wave with a frequency in the ultrasonic range is produced. In this case, a transmission frequency, i.e., the frequency at which the sound waves propagate, can be in a range of 47 to 52 kHz, for example. The emitted sound waves thus form the respective ultrasonic signal. In this case, the first ultrasonic sensor 4, in response to the control, emits, for example, a first ultrasonic signal 4a, while the second ultrasonic sensor 4, in response to the control, emits, for example, a second ultrasonic signal 5a.

[0059] In order to achieve the desired increase in range, the ultrasonic signals 4a, 5a are now coordinated with one another in such a way that a signal amplification occurs. For this purpose, the two ultrasonic sensors 4, 5 are initially arranged next to one another in their respective installation positions in the vehicle 1 at a predetermined distance d. The distance d is selected such that the ultrasonic signals 4a, 5a overlap depending on their respective signal characteristics in an overlap region 6 predetermined by the distance d. The signal characteristic indicates in particular the directivity of the respective ultrasonic signal 4a, 5a. This means that the signal characteristic determines the angle to the respective ultrasonic sensor 4, 5 at which a signal strength of the respective ultrasonic signal 4a, 5a lies within a predetermined optimal range. In the exemplary embodiment in Fig.2, the signal characteristic of the ultrasonic signals 4a, 5a is schematically represented, for example, by the dashed conical area emanating from each of the sensors 4, 5.

[0060] The overlay region 6 is the region where the conical signal characteristics overlap. This overlay results in a superposition of the wavefronts of the ultrasonic signals 4a, 5a. The ultrasonic signals 4a, 5a overlap in the overlay region 6 to form a superposition signal 6a.

[0061] To achieve signal amplification in response to the superposition, the signal parameters of the ultrasonic signals 4a, 5a are selected or adjusted such that the ultrasonic signals 4a, 5a amplify upon superposition. The superposition signal 6a thus results from constructive interference of the ultrasonic waves. A gain value that indicates the amplification depends, for example, on the intersection point of the wavefronts and results from the sum of the amplitude values ​​of the respective ultrasonic signals 4a, 5a. The signal amplification thus represents an increase in amplitude.

[0062] To better understand signal amplification, Fig. 4 shows an example amplitude-time diagram for the ultrasonic signals 4a and 5a and the overlay signal 6a. The time t is entered on the x-axis of the diagram, while the respective signal amplitude Amp is shown on the y-axis. The diagram shows a snapshot of the signals, for example at a predetermined distance from the ultrasonic sensors 4, 5. As shown in Fig. 4, during superposition, the amplitude values ​​of the ultrasonic signals 4a, 5a add up to the amplitude value of the overlay signal 6a. The amplitude and signal curve of the overlay signal 6a thus result from the sum of the amplitude and signal curves of the ultrasonic signals 4a and 5a. The signal parameters are selected so that the total amplitude is maximum.

[0063] In order to achieve the desired signal amplification, the distance d and the signal parameters of the ultrasonic signals 4a, 5a play a role. This means that the distance d and the signal parameters must be selected or adjusted accordingly to result in the appropriate signal amplification. The distance d or the signal parameters can, for example, be determined for each vehicle model in test experiments or through simulations. The determined values ​​can, for example, be stored in a data memory in the form of a lookup table or assignment table and retrieved by the control device 8. Based on the table, the control device 8 can adjust the signal parameters accordingly. The distance d is fixed, in particular when installing the ultrasonic sensor device 3 or during manufacture of the ultrasonic sensor device 3 by a manufacturer.Depending on the installation position, different distances between the ultrasonic sensors 4, 5 and different signal parameters may be advantageous. For example, the distance d can be between 30 and 90 cm depending on the installation position. As can be seen in Fig. 2, the distance d also results in a blind area 7 in which no superposition of the ultrasonic signals 4a, 5a occurs. The superposition, i.e., the superposition area 6, thus only begins at a predetermined distance or at a predetermined distance from the ultrasonic sensors 4, 5.

[0064] The signal parameters to be set can be, for example, a transmission frequency and a signal transmission time. The signal transmission time t1, t2 specifies the start of transmission for the respective ultrasonic signal 4a, 5a. The transmission frequency f1, f2 specifies the frequency or frequencies with which the ultrasonic signal is output, for example in the form of a so-called burst. In connection with the transmission frequency f1, f2, it is possible to transmit ultrasonic signals 4a, 5a with a constant frequency. The ultrasonic signals 4a, 5a in particular have different transmission frequencies f1, f2, i.e. different frequency values ​​of the transmission frequency f1, f2. Alternatively, there is the option of transmitting the ultrasonic signals 4a, 5a as a so-called chirp. The burst comprises a frequency spectrum with several different frequency values, which are output sequentially from low to high or vice versa.Here, too, the ultrasonic signals 4a, 5a preferably differ in their respective transmission frequencies f1, f2, which are to be understood in particular as the center frequency of all frequencies present in the frequency spectrum. By selecting different transmission frequencies, the sender of the reflected ultrasonic signal can be determined during a subsequent evaluation of the echo signal, which is necessary, for example, for determining the position of object 9.

[0065] As shown in Fig. 2, the transmission times t1, t2 can also differ to generate the desired superimposed signal 6a. According to Fig. 2, for example, the first ultrasonic signal 4a was transmitted earlier than the second ultrasonic signal 5a.

[0066] The signal parameters can also be used to direct the overlay signal 6a, i.e. to specify a direction for the overlay signal 6a. Fig. 2 shows the ultrasonic sensor device 3 in a first operating mode, in which the overlay signal 6a is emitted straight ahead along a central axis M between the ultrasonic sensors 4, 5 in a main beam direction R. This means that the amplitude maxima arise in the main beam direction R straight ahead along the central axis M. In contrast, Fig. 3 shows a schematic representation of the ultrasonic sensor device 3 according to Fig. 2, which is operated in a second operating mode in which the overlay signal 6a is emitted obliquely or laterally relative to the central axis M. The signal parameters are adapted accordingly for this purpose. For example, the first ultrasonic signal 4a can have a transmission frequency f1 that is designed as a chirp.The ultrasonic signal 5a, on the other hand, has a transmission frequency f2 with a constant frequency value. Furthermore, the transmission time t2 of the ultrasonic signal 5a occurs earlier than the transmission time t1 of the ultrasonic signal 4a. This results in a radial shift of the main beam direction R of the superimposed signal 6a relative to the central axis M, which is tilted to the left in the illustration in Fig. 3.

[0067] To achieve the desired directivity, the signal parameters, i.e., the transmission frequency and the signal transmission time, are modified. The directed transmission of the overlay signal 6a makes it possible to simplify the position determination using triangulation. When detecting the resulting echo signal, the control device 8 can, for example, filter the received signals so that only echoes from the main beam direction R, in which the overlay signal 6a has propagated, are received. This makes it possible to infer the position of the object 9 using triangulation with a smaller number of echoes or signal paths.

[0068] For object detection, it may be advantageous to pan or sweep the main beam direction R of the overlay signal 6a. This allows the surroundings to be scanned for objects in multiple directions. Additionally or alternatively, it is possible to select the main beam direction R depending on an expected area in which an object 9 is expected in the surroundings U. The expected area can be selected depending on a movement maneuver of the vehicle, such as the parking maneuver described above. In the present exemplary embodiment, for example, it is expedient to only monitor the area of ​​the vehicle 1 to the right of the travel path F.

[0069] Fig. 5 once again schematically shows a process flow diagram for a method for operating an ultrasonic sensor device 3 of a vehicle 1, as described above by way of example. The method can be executed by the respective control device 8. In the method, in a step S1, the distance d between the ultrasonic sensors 4, 5 can, for example, first be detected or determined by means of the control device 8. For example, the distance can be retrieved from a data memory as a stored value depending on the installation position of the associated ultrasonic sensor device 3.

[0070] In a step S2, the signal parameters for generating the desired superposition signal 6a are then recorded. The control device 8 can read or retrieve the signal parameters, i.e. the respective signal transmission time t1, t2, from the aforementioned lookup table depending on the desired main beam direction R. Based on the distance d and the signal parameters, the control device 8 can now generate a corresponding control signal for each of the ultrasonic sensors 4, 5. In a step S3, the control device 8 can control the ultrasonic sensors 4, 5 with the corresponding control signal. When subjected to the control signal, the ultrasonic sensors 4, 5 are caused to transmit the respective ultrasonic signal 4a, 5a with the desired signal parameters. During transmission, the signals overlap, resulting in the desired signal amplification.This allows the range at which the ultrasonic signals 4a, 5a are transmitted relative to the vehicle 1 to be increased. Objects 9 at a greater distance can be identified, or objects 9 close to the vehicle 1 can be detected with greater precision or accuracy.

[0071] Overall, the embodiments thus show the signal amplification and alignment by superposition of emitted ultrasonic signals 4a, 5a.

Claims

Patent claims 1 . Ultrasonic sensor device (3) for a vehicle (1), comprising: - a first ultrasonic sensor (4) and at least one second ultrasonic sensor (5), and at least one control device (8), wherein - the control device (8) is designed to control the first ultrasonic sensor (4) to emit a first ultrasonic signal (4a) with first signal parameters and to control the at least second ultrasonic sensor (5) to emit a second ultrasonic signal (5a) with second signal parameters, wherein - the first and the at least second ultrasonic sensor (4, 5) are arranged next to one another in a predetermined installation position in the vehicle (1) at a predetermined distance (d), wherein - the first and at least second ultrasonic signals (4a, 5a) are superimposed upon transmission in an overlay region (6) predetermined by the distance (d) to form an overlay signal (6a), and the overlay signal (6a) is amplified in comparison to the first and at least second ultrasonic signals (4a, 5a) by an amplification value predetermined by their signal parameters.

2. Ultrasonic sensor device (3) according to claim 1, wherein the control device (8) is designed to specify a transmission frequency (f1, f2) and / or a signal transmission time (t1, t2) for the first and at least second ultrasonic signal (4a, 5a) as respective signal parameters.

3. Ultrasonic sensor device (3) according to claim 2, wherein the control device (8) is designed to modify the transmission frequency (f1, f2) and the signal transmission time (t1, t2) for the first and the at least second ultrasonic signal (4a, 5a) according to a predetermined first modification criterion such that the superposition signal (6a) has a main beam direction (R) along a central axis (M) between ultrasonic sensors (4, 5).

4. Ultrasonic sensor device according to one of the preceding claims 2 or 3, wherein the control device (8) is designed to modify the transmission frequency (f1, f2) and the signal transmission time (t1, t2) for the first and the at least second ultrasonic signal (4a, 5a) according to a predetermined second modification criterion such that the superposition signal (6a) has a main beam direction (R) oblique to a central axis (M) between ultrasonic sensors (4, 5).

5. Ultrasonic sensor device (3) according to one of the preceding claims 3 and 4, wherein the control device (8) is designed to control the first and the at least second ultrasonic sensor (4, 5) for providing the superposition signal (6a) in at least two different main beam directions (R) relative to the central axis (M).

6. Ultrasonic sensor device (3) according to one of the preceding claims 3 to 5, wherein the control device (8) is designed to select the respective main beam direction (R) depending on an expectation range in which an object (9) in the environment (U) is expected depending on a previously known movement maneuver of the vehicle (1).

7. Ultrasonic sensor device (3) according to one of the preceding claims, wherein the first ultrasonic signal (4a) has as signal parameter a transmission frequency (f1) with a first frequency value, and the second ultrasonic signal (5a) has as signal parameter a transmission frequency (f2) with a different second frequency value.

8. Ultrasonic sensor device (3) according to one of the preceding claims, wherein the first ultrasonic signal (4a) has, as a signal parameter, a transmission frequency (f1) with a first frequency spectrum, and the second ultrasonic signal (5a) has, as a signal parameter, a transmission frequency (f2) with a different second frequency spectrum, wherein the frequency values ​​contained in the first and second frequency spectrum are contained in ascending or descending order.

9. Ultrasonic sensor device (3) according to one of the preceding claims, wherein the first and the at least second ultrasonic sensor (4, 5) are designed to output ultrasonic signals (4a, 5a) with a transmission frequency in a range of 47 to 52 kHz.

10. Ultrasonic sensor device (3) according to one of the preceding claims, wherein the first and / or the at least second ultrasonic sensor (4, 5) are designed to receive an echo signal as a reflected first and / or second ultrasonic signal (4a, 5a) and / or superposition signal (6a) at an object (9) in the environment (U), and the ultrasonic sensor device (3) comprises an evaluation device which is designed to evaluate the echo signal according to a predetermined evaluation principle for determining a distance and / or a position and / or a geometry of the object (9) relative to the ultrasonic sensor device (3).

11. Vehicle (1) with at least one ultrasonic sensor device (3) according to one of the preceding claims.

12. Vehicle (1) according to claim 11, wherein the ultrasonic sensors (4, 5) of the at least one ultrasonic sensor device (3) are mounted in the installed position on a vehicle door, a tailgate and / or a bumper.

13. A method for operating an ultrasonic sensor device (3) for a vehicle (1), wherein the ultrasonic sensor device (3) comprises a first ultrasonic sensor (4) and at least one second ultrasonic sensor (5), as well as at least one control device (8), wherein the first ultrasonic sensor (4) is controlled by the control device (8) to emit a first ultrasonic signal (4a) with first signal parameters and the at least second ultrasonic sensor (5) is controlled to emit a second ultrasonic signal (5a) with second signal parameters, wherein the first and at least second ultrasonic sensors (4, 5) are arranged next to one another in a predetermined installation position in the vehicle (1) at a predetermined distance (d), and the first and at least second ultrasonic signals (4a, 5a) are superimposed during transmission in an overlay region (6) predetermined by the distance (d) to form an overlay signal (6a),and the beat signal (6a) in comparison with the first and the, at least second ultrasonic signal (4a, 5a) is amplified by an amplification value predetermined by its signal parameters.

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