DE102022131308A1 - Multi-channel ultrasonic measuring unit and corresponding method and computer program product - Google Patents

Abstract

The invention relates to an ultrasonic measuring unit, in particular for use in a vehicle, comprising a control unit and an evaluation unit, wherein the control unit is designed to control an ultrasonic transducer for alternately transmitting ultrasonic signals on different channels, wherein the evaluation unit is designed to evaluate echoes resulting from the ultrasonic signals on the channels for detecting at least one object causing the echoes.

Description

The invention relates to an ultrasonic measuring unit, in particular for use in a vehicle, a method for operating an ultrasonic measuring unit and a corresponding computer program product.

Motor vehicles are increasingly being equipped with ultrasonic sensors, which are typically integrated into the bodywork and are designed to help the driver to detect obstacles in the path of the motor vehicle in good time, particularly in areas that are difficult for the driver to see, and to estimate the distance of obstacles. The functionality of such an ultrasonic sensor is based on the transmission of ultrasonic signals and the detection of echoes of the transmitted ultrasonic signals that emanate from obstacles that may be in the sensor's detection range. The ultrasonic pulses generated for this purpose can have a temporally constant frequency. Approaches with temporally variable frequency ("chirp") and several separate transmission and reception channels (e.g. through frequency multiplexing) are also known.

Ultrasonic sensors are used in a wide variety of applications today, from parking aids to assistance systems for blind spots (“dead-spot detection”). Ultrasonic sensors have so far been used very little in the field of autonomous driving in urban environments (“urban driving”). The reason for this is, on the one hand, the desire for higher-performance systems, especially in partially or fully automated driving, but also the limitation of the range in combination with the sampling rate of the ultrasonic sensors, which is limited by the speed of sound.

The speed of sound largely determines the range and sampling rate of an ultrasonic sensor. Today, ranges of up to 10 m are already conceivable with ultrasonic sensors in the automotive sector. Due to the speed of sound, such a measurement with an ultrasonic sensor takes 60 ms under normal conditions. In the best case, this would allow 16 measurements per second. If several sensors are used in a system and several measurement steps are required to fully cover the system, the measurement rate for the complete system typically falls to 5 - 8 updates per second. Such a low update rate has significant negative consequences for object detection and, in particular, for object tracking, which is why it is not applicable today.

The invention is based on the object of providing an improved ultrasonic measuring unit with a corresponding method and computer program product. The objects underlying the invention are solved by the features of the independent patent claims. Embodiments are specified in the dependent patent claims.

• - die Kontrolleinheit ausgebildet ist, einen Ultraschallwandler anzusteuern zum abwechselnden Senden von Ultraschallsignalen auf unterschiedlichen Kanälen,
• - die Auswerteeinheit ausgebildet ist, aus den Ultraschallsignalen auf den Kanälen resultierende Echos zur Detektion zumindest eines die Echos verursachenden Objekts auszuwerten.

To solve the problem, an ultrasonic measuring unit is provided, in particular for use in a vehicle, which comprises a control unit and an evaluation unit, wherein

• - the control unit is designed to control an ultrasonic transducer for alternately transmitting ultrasonic signals on different channels,
• - the evaluation unit is designed to evaluate echoes resulting from the ultrasonic signals on the channels in order to detect at least one object causing the echoes.

According to the invention, the ultrasonic measuring unit transmits ultrasonic signals, such as ultrasonic pulses, alternately on two or more different channels. The term "channel" refers to any property of an ultrasonic signal by means of which the evaluation unit can distinguish an echo of a first ultrasonic signal that was transmitted on a first of the two or more different channels from an echo of a second ultrasonic signal that was transmitted on a different, second of the two or more different channels. Without limitation, such a property defining a channel could include a characteristic frequency, a characteristic frequency spectrum, a characteristic temporal frequency curve, a characteristic amplitude and/or a characteristic phase angle at the beginning of the transmission process of the respective ultrasonic signal.

The ultrasonic measuring unit could use one or more ultrasonic transducers for sending and receiving. Several ultrasonic transducers could be used to send ultrasonic signals, but at least two ultrasonic signals are sent alternately on different channels on each ultrasonic transducer used for sending. For example, the transmitting ultrasonic transducers could be designed specifically for the two or more channels implemented. Using the same ultrasonic transducer for sending on different channels could make it possible to achieve very efficient obstacle detection with minimal technical effort and material use. Obstacle detection is possible with a high sampling rate.

In principle, some or all of the echoes to be processed by the evaluation unit can be received by the same ultrasonic transducer through which the respective original signal of the echoes was sent. This could also reduce the technical effort and material required for the application of multi-channel ultrasound for obstacle detection. However, one or more additional ultrasonic transducers could just as easily be used to receive an echo of an ultrasonic signal that was sent by a transmitting ultrasonic transducer. Preferably, some or all of the ultrasonic transducers can transmit and receive on all implemented channels. Alternatively, the available ultrasonic sensors could be divided into those that only transmit and/or receive on some of the channels and those that only transmit and/or receive on another part of the channels. In particular, each of the receiving ultrasonic transducers could be assigned to one or more of the channels or be designed to receive on one or more of the channels. Ultrasonic transducers specific to one or more of the channels could be structurally different from one another in order to better meet the specific requirements for the channels implemented for each ultrasonic transducer. For example, the channels could correspond to different frequency ranges, and the ultrasonic transducers operating on different frequency ranges could be optimized accordingly for maximum efficiency for converting in the respective frequency range.

Ultrasonic transducers could also be used that are specifically designed to transmit ultrasonic signals or specifically to receive echoes with a smaller amplitude than the original ultrasonic signals underlying the echoes. Transmitting and receiving transducers can be structurally different from one another in order to better meet the specific requirements of transmitting and receiving. For example, a transmitting ultrasonic transducer could be designed to represent ultrasonic signals with a large amplitude with as little distortion as possible, while a receiving ultrasonic transducer could be designed to detect the echoes of the ultrasonic signals with as much sensitivity and as little noise as possible.

The control unit and the evaluation unit could be implemented as different units or assemblies that operate independently of one another in terms of signal technology. Alternatively, the control unit and the evaluation unit could be integrated into the same assembly or unit. For example, the control unit and the evaluation unit could be realized by means of analog or digital electronics, in particular in the form of one or more integrated circuits. The control unit and the evaluation unit could also be implemented as software modules that run on a generic or specialized processor, in particular a central processing unit (CPU). One or more communication channels can be implemented between the control unit and the evaluation unit, which enable a transmission of signals between the two said units that goes beyond the transmission of ultrasonic signals and the reception of echoes of these transmitted ultrasonic signals.

The control unit preferably controls an ultrasonic transducer by outputting an electrical signal. The ultrasonic transducer could then be designed to convert between electrical energy and mechanical vibrations. For example, an ultrasonic transducer could have a membrane that is excited by a piezo element to send an ultrasonic signal or that is set into acoustic vibrations when an ultrasonic signal is received and transmits these to the piezo element. The electrical signal corresponding to a received ultrasonic signal and output by the piezo element could then be received and evaluated by the evaluation unit.

According to one embodiment, the control and evaluation takes place in a measuring cycle, with the measuring cycle being carried out cyclically. In particular, this could make it possible to detect a change in the distance between the transmitting ultrasonic transducer and an obstacle. As the explanations below show in more detail, the alternating transmission of ultrasonic signals on different channels could not only effectively increase the detection rate for obstacles, but in particular also enable the measurement of several distance ranges (e.g. a close range of up to 5 m and a long range of 5 to 10 m) almost simultaneously with a high or optimized sampling rate for the close range. In particular, a cyclical repetition of the measuring cycle could make it possible to receive echoes of ultrasonic signals that were sent in an earlier measuring cycle. In this way, for example, continuous detection of obstacles within the detection range with a high sampling rate is possible.

According to one embodiment, within the measuring cycle, the ultrasonic signals comprise at least a first ultrasonic signal on a first channel and a second ultrasonic signal on a second channel. The ultrasonic measuring unit will therefore initially emit a first ultrasonic signal on a first channel. Following this, the Ultrasonic measuring unit receives echoes originating from the first ultrasonic signal during a predetermined first reception period. Due to the immediate temporal proximity to the transmission of the first ultrasonic signal, the echoes received in this first reception period originate from an obstacle reflection from a "close range" relative to the ultrasonic transducer.

Following the first reception period, but still in the same measurement cycle, the ultrasonic measuring unit will transmit a second ultrasonic signal on a second channel. The second channel is different from the first channel. Following this, the ultrasonic measuring unit can receive echoes of the second ultrasonic signal during a predetermined second reception period, which again originate from the near area but are received on the second channel.

According to one embodiment, the evaluation takes into account echoes resulting at least on the first channel between the transmission of the two ultrasonic signals, and the evaluation takes into account echoes resulting on the first and second channels after the transmission of the second ultrasonic signal. Within the second reception period, the ultrasonic measuring unit can therefore additionally receive echoes of the first ultrasonic signal previously transmitted on the first channel on the first channel. Since the echoes received in the second reception period have already propagated over the duration of the first reception period and the duration of the transmission of the second ultrasonic signal, they provide information about obstacles that scatter the first ultrasonic signal back to an ultrasonic transducer connected to the ultrasonic measuring unit from a greater distance corresponding to this longer propagation period.

If we consider the entire measurement cycle, it is possible to detect obstacles in the near and far range using the individual transmitting ultrasonic transducer within the measurement cycle, whereby the sampling rate in the near range is twice as high as for the far range, for example. In this way, in addition to the two measurements in the near range, a measurement in a far range can also be carried out in the second reception period without limiting the repetition rate.

For example, the ultrasonic measuring unit is designed to simultaneously receive echoes of ultrasonic signals on at least two channels (the channels mentioned above), with as little pause as possible between two measurements and the measurement times being known precisely. In particular, it could be advantageous if the channels have a low "coupling", i.e. if the transmission of the second ultrasonic signal on the second channel does not affect the reception of echoes on the first channel. In this case, the ultrasonic measuring unit could continue to receive echoes of the first ultrasonic signal on the first channel even while the second ultrasonic signal is being transmitted, so that there is no "blind area" between the echoes from the near range and the echoes from the far range. Such a blind area would correspond to a spatial area in which no obstacle can be detected ("blind spot").

The above example illustrates basic ideas of the invention using ultrasonic signals that are sent and received on two channels. Of course, the ultrasonic measuring unit could also send more than two ultrasonic signals on more than two different channels. It could also be designed to receive echoes of the ultrasonic signals sent on the channels. In this way, the spatial detection range of the ultrasonic measuring unit could be divided into more than two distance ranges. In a three-channel ultrasonic measuring unit, for example, there could initially be a close range from which echoes of the ultrasonic signals are received on all three channels within a single measuring cycle. There can also be a medium distance range from which echoes are received on the first two channels within the same measuring cycle. Finally, in this case there can also be a long range from which only echoes of the first ultrasonic signal sent earliest are received on the first channel within the same measuring cycle. The concept can easily be transferred to any other number of channels per measuring cycle.

According to one embodiment, a maximum spatial measuring distance is defined for the ultrasonic measuring unit, wherein the length of the measuring cycle is set such that an echo resulting from the first ultrasonic signal, which is caused by a reflection from an object located at the maximum measuring distance, can be detected within the measuring cycle. The maximum spatial measuring distance (also referred to herein as range) is the maximum distance within which a detectable obstacle can be located. An echo resulting from this furthest obstacle is thus detectable during the measuring cycle. It results from the earliest transmitted ultrasonic signal during this measuring cycle.

An ultrasonic signal transmitted by an ultrasonic transducer propagates at a speed of sound of typically c ≈ 343 m/s. Within The ultrasonic signal travels a distance x = ct over a time t. For an obstacle at a distance L, this results in a transit time of the ultrasonic signal of Δt = 2L/c between the transmission of the ultrasonic signal and the detection of the echo from the distance L. For a cycle duration T, this gives a maximum spatial measuring distance of L _max = cT/2. If, for example, a range of 10 m is required, this requires a cycle duration of 60 ms within a tolerance of, for example, 5%.

With alternating transmission on N channels, the cycle duration is divided into T/N sub-intervals, each of which contains a transmission period for transmission on one of the N channels and a reception period for receiving echoes. The echoes of ultrasonic signals that were transmitted in a previous sub-interval arriving in a second or later sub-interval could result in a greater range for the multi-channel ultrasonic measuring unit disclosed here compared to a single-channel ultrasonic measuring unit with a cycle duration T _1K = T _2K N (eg twice the range when using two channels), without having to worry about limitations in the measurement rate for the short range.

It should be noted that the multi-channel ultrasonic measuring unit disclosed herein could monitor closer sections (distance ranges) of _the detection range defined by the range, e.g. the near range, at a higher sampling rate than more distant sections (distance ranges) of the detection range (e.g. the far range), compared to a single-channel ultrasonic measuring unit with _the same cycle duration T 1K = T 2K. This is because the ultrasonic measuring unit does not have to wait until the start of a new measurement cycle until a new ultrasonic signal is emitted that allows monitoring of the near range. Instead, it can use the travel time of the echoes from the more distant distance ranges to transmit ultrasonic signals on other channels in order to achieve higher frequency monitoring of the near range.

For the example of a two-channel ultrasonic measuring unit, which is preferred here without restriction to simplify the illustration, this means that objects in the close range can be detected and objects in the far range can be identified at an early stage. This could result in possible applications, particularly in urban areas. For example, the ultrasonic measuring unit could be used in a motor vehicle to determine whether a turning lane is occupied or not. The greater range of the ultrasonic measuring unit could enable this function even if this turning lane is more than one lane away from the lane currently being used. A high sampling rate, such as that made possible by the invention, will be particularly relevant for the close range. Here, short-term changes in distance to an obstacle can have a greater risk than for the far range.

According to one embodiment, the evaluation unit is designed to constantly evaluate echoes resulting from the ultrasonic signals on all channels within the measurement cycle. In this way, the evaluation unit could evaluate echoes (originating from the previous measurement cycle) on a given channel at any time during a repetition of the measurement cycle, but in particular also in an "early" reception period. In this way, a more distant distance range within the range of the ultrasonic measuring unit could be continuously monitored at the same measurement rate as a distance range closer to the transmitting ultrasonic transducer. The transit time of the echo received before a new transmission on the given channel can be reconstructed from the reception time and the characteristics of the channel on which the echo was received if the transmission pattern is known (i.e. in which subinterval of a given measurement cycle which channel is transmitted).

According to one embodiment, the evaluation unit is designed to receive the echoes from the same ultrasonic transducer from which the ultrasonic signals were sent. Compared to an ultrasonic measuring unit with different transducers for sending and receiving, it might therefore be sufficient to equip the ultrasonic measuring unit with a single ultrasonic transducer. This could result in a simpler structure of the ultrasonic measuring unit with less material being used.

According to one embodiment, the different channels comprise at least three channels, wherein within the measuring cycle the successive ultrasonic signals are transmitted at different time intervals, wherein the different time interval is constant for the cyclically repeating execution of the measuring cycle. Within a given first measuring cycle, ultrasonic signals transmitted consecutively on a first pair of channels are transmitted at a time interval t ₁ . The time interval t ₁ differs from a time interval t ₂ in which successive ultrasonic signals are transmitted on another, second pair of channels within the same measuring cycle. The requirement that the different time interval is constant for the cyclically repeating execution of the measuring cycle means that that in another, second measurement cycle, the ultrasonic signals transmitted on the first pair of channels are transmitted at the same time interval as in the first measurement cycle. Due to this, the spatial area of the "blind spot" described above can be minimized or even eliminated.

During the transmission of an ultrasonic signal, it may happen that the evaluation unit cannot detect echoes of a first ultrasonic signal in a second transmission period, during which a second ultrasonic signal is transmitted following the first ultrasonic signal (“blind area, blind spot”). As long as transmission is taking place and possibly also afterwards due to the membrane of the ultrasonic transducer oscillating, the detection capability of this same transducer may be reduced or even prevented. The duration of the actual “transmission period” of an ultrasonic signal can, for example, extend well beyond the duration of the actual control signal causing the excitation force due to the ultrasonic transducer oscillating after the excitation force has ceased.

As already explained above, the use of at least three channels by alternately transmitting can enable the measuring cycle to be divided into at least three corresponding sub-intervals and the spatial detection range for obstacles to be divided into at least three distance ranges corresponding to the sub-intervals. If the time intervals between two transmissions are varied from measuring cycle to measuring cycle, the size of the undetectable, "blind" distance range at the transition between two adjacent distance ranges can be reduced overall.

According to one embodiment, when the measuring cycle is carried out cyclically, the successive ultrasonic signals are transmitted at different time intervals for at least some of the measuring cycles. If, for example, in two measuring cycles the transmission time of the second ultrasonic signal is varied by a time difference +Δt or -Δt, the ultrasonic transducer can still receive echoes of ultrasonic signals in one of the measuring cycles during the time period Δt in which a new ultrasonic signal would otherwise have already been transmitted. Compared to dividing the measuring cycle into equally long partial intervals, this reduces the area of possible "blind spots". For example, the relative variation of the time interval for a given pair of channels used consecutively to transmit ultrasonic signals in different measuring cycles is at least 3%, preferably at least 5%.

According to one embodiment, the ultrasonic measuring unit further comprises the ultrasonic transducer, wherein the ultrasonic transducer is designed to receive the echoes resulting from the ultrasonic signals on all channels and to transmit them to the evaluation unit. This does not exclude the possibility that the ultrasonic measuring unit can have more than one ultrasonic transducer. In the case that the ultrasonic measuring unit has more than one ultrasonic transducer, it is again implied that echoes that a given ultrasonic transducer detects do not necessarily have to originate from ultrasonic signals that were sent via the same ultrasonic transducer.

• - Durch die Kontrolleinheit, Ansteuern eines Ultraschallwandlers zum abwechselnden Senden von Ultraschallsignalen auf unterschiedlichen Kanälen,
• - Durch die Auswerteeinheit, Auswerten von aus den Ultraschallsignalen auf den Kanälen resultierende Echos zur Detektion zumindest eines die Echos verursachenden Objekts.

In a further aspect, the invention provides a method for operating an ultrasonic measuring unit, in particular for use in a vehicle, wherein the ultrasonic measuring unit comprises a control unit and an evaluation unit, the method comprising:

• - Through the control unit, controlling an ultrasonic transducer to alternately send ultrasonic signals on different channels,
• - By the evaluation unit, evaluation of echoes resulting from the ultrasonic signals on the channels in order to detect at least one object causing the echoes.

In a further aspect, the invention provides a computer program product, in particular a computer-readable storage medium, wherein the computer program product comprises computer-executable code, wherein the code is executable by at least one processor of a computing device to cause the computing device to perform the method disclosed herein.

Those skilled in the art will understand that aspects of the present invention may be embodied as an apparatus, method, or computer program or computer program product. Accordingly, aspects of the present invention may take the form of a purely hardware embodiment, a purely software embodiment (including firmware, software in memory, microcode, etc.), or an embodiment combining software and hardware aspects, all of which may be referred to generally herein as a "circuit,""module," or "system." Furthermore, aspects of the present invention may take the form of a computer program product carried by one or more computer-readable media in the form of computer-executable code. A computer The term "computer executable code" also includes computer executable code. "Computer executable code" may also be referred to as "computer program instructions".

Any combination of one or more computer-readable media may be used. The computer-readable medium may be a computer-readable signal medium or a computer-readable storage medium. A “computer-readable storage medium” as used herein includes a tangible storage medium capable of storing instructions executable by a processor of a computing device. The computer-readable storage medium may be referred to as a computer-readable non-transitory storage medium. The computer-readable storage medium may also be referred to as a tangible computer-readable medium. In some embodiments, a computer-readable storage medium may also be capable of storing data that allows it to be accessed by the processor of the computing device. Examples of computer-readable storage media include, but are not limited to: a floppy disk, a magnetic hard disk, a solid-state hard disk, flash memory, a USB flash drive, random access memory (RAM), read-only memory (ROM), an optical disk, a magneto-optical disk, and the processor's register file. Examples of optical disks include compact disks (CD) and digital versatile disks (DVD), for example, CD-ROM, CD-RW, CD-R, DVD-ROM, DVD-RW, or DVD-R disks. The term computer-readable storage medium also refers to various types of recording media that are adapted to be accessed by the computing device over a network or communications link. For example, data may be accessed via a modem, over the Internet, or over a local area network. Computer executable code embodying a computer-readable medium may be transmitted over any suitable medium, including, but not limited to, wireless, wired, fiber optic, RF, etc., or any suitable combination of the foregoing media.

A computer-readable signal medium may include a propagated data signal containing the computer-readable program code, for example, in a baseband or as part of a carrier signal (carrier wave). Such a propagated signal may be in any form, including, but not limited to, an electromagnetic form, an optical form, or any suitable combination thereof. A computer-readable signal medium may be any computer-readable medium other than a computer-readable storage medium that can transmit, disseminate, or transport a program for use by or in connection with an instruction-executing system, device, or apparatus.

"Computer memory" or "memory" is an example of a computer-readable storage medium. Computer memory is any memory that is directly accessible by a processor.

"Computer storage" or "data storage" is another example of a computer-readable storage medium. Computer storage is any non-transitory computer-readable storage medium. In some embodiments, a computer memory can also be a computer data storage, or vice versa.

A "processor" as used herein includes an electronic component capable of executing a program or machine-executable instruction or computer-executable code. A reference to the computing device comprising a "processor" should be interpreted to potentially include more than one processor or processing cores. The processor may, for example, be a multi-core processor. A processor may also refer to a collection of processors within a single computer system or distributed across multiple computer systems. The term computing device or computer should also be interpreted to potentially refer to a collection or network of computing devices or computers, each comprising a processor or processors. The computer-executable code may be executed by multiple processors, which may be within the same computing device or even distributed across multiple computers.

Computer executable code may comprise machine-executable instructions or a program that causes a processor to perform an aspect of the present invention. Computer executable code for performing operations for aspects of the present invention may be written in any combination of one or more programming languages, including an object-oriented programming language such as Java, Smalltalk, C++, or the like, and conventional procedural programming languages such as the "C" programming language or similar programming languages, and translated into machine-executable instructions. In some cases, the computer executable code may be in the form of a high-level programming language or in a pre-translated form, and used in conjunction with an interpreter that generates the machine-executable instructions.

The computer executable code may run entirely on a user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer, or entirely on the remote computer or server. In the latter case, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to a remote computer (for example, over the Internet using an Internet service provider).

The computer program instructions can be executed on one processor or on several processors. In the case of several processors, these can be distributed across several different entities (e.g. clients, servers). Each processor could execute a part of the instructions intended for the respective entity. Therefore, when a system or method is mentioned that includes several entities, the computer program instructions are understood to be adapted to be executed by a processor assigned to or associated with the respective entity.

Aspects of the present invention are described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It is noted that each block or portions of the blocks of the flowcharts, illustrations and/or block diagrams may be implemented by computer program instructions, optionally in the form of computer executable code. It is further noted that combinations of blocks in different flowcharts, illustrations and/or block diagrams may be combined if they are not mutually exclusive. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer or other programmable data processing device to produce a device such that the instructions executed via the processor of the computer or other programmable data processing device produce means for performing the functions/steps specified in the block or blocks of the flowcharts and/or block diagrams.

These computer program instructions may also be stored on a computer readable medium that can direct a computer or other programmable data processing apparatus or other apparatus to function in a particular manner such that the instructions stored on the computer readable medium produce an article of manufacture, including instructions that implement the function/step specified in the block or blocks of the flowcharts and/or block diagrams.

The computer program instructions may also be stored on a computer, other programmable data processing apparatus, or other devices to cause execution of a series of process steps on the computer, other programmable data processing apparatus, or other devices to produce a computer-executable process, such that the instructions executing on the computer or other programmable devices produce methods for implementing the functions/steps set forth in the block or blocks of flowcharts and/or block diagrams.

• 1 ein mit einer Ultraschallmesseinheit ausgestattetes Kraftfahrzeug,
• 2A einen Sende- und Empfangsvorgang auf einem ersten Kanal einer Ultraschallmesseinheit,
• 2B einen Sendevorgang auf einem zweiten Kanal und einen Empfangsvorgang auf einem ersten und einem zweiten Kanal einer Ultraschallmesseinheit,
• 3 ein Blockdiagramm von Komponenten einer Ultraschallmesseinheit,
• 4 ein Blockdiagramm von Komponenten einer Ultraschallmesseinheit,
• 5 ein Ablaufdiagramm eines Verfahrens zum Betrieb einer Ultraschallmesseinheit,
• 6 ein Zeitdiagramm einer an einem Ultraschallwandler auf einem Kanal gemessenen Ultraschallamplitude, und
• 7 eine Darstellung einer zeitlichen Aufteilung eines Messzyklus.

Further advantages and features can be found in the following description in conjunction with the attached drawings. These show:

• 1 a motor vehicle equipped with an ultrasonic measuring unit,
• 2A a transmission and reception process on a first channel of an ultrasonic measuring unit,
• 2 B a transmission process on a second channel and a reception process on a first and a second channel of an ultrasonic measuring unit,
• 3 a block diagram of components of an ultrasonic measuring unit,
• 4 a block diagram of components of an ultrasonic measuring unit,
• 5 a flow chart of a method for operating an ultrasonic measuring unit,
• 6 a time diagram of an ultrasonic amplitude measured on an ultrasonic transducer on one channel, and
• 7 a representation of a temporal division of a measurement cycle.

Ultrasonic measuring systems are increasingly being used, particularly in automotive engineering, to detect obstacles and measure their distance. 2A and 2 B show examples of the alternating transmission of ultrasonic signals 210, 220 on different channels and receiving echoes 212, 214, 222 of the transmitted ultrasonic signals 210, 220. For this purpose, the 3 Ultrasonic measuring unit 300 shown or the one in 4 An ultrasonic measuring unit 300, 400 could be used to measure the 5 The method 500 shown can be implemented for operating an ultrasonic measuring unit in order to detect objects 202, 204 in the vicinity of, for example, a motor vehicle 100, 200. For this purpose, ultrasonic signals 210, 220 can be sent in the direction of the objects 202, 204, their echoes 212, 214, 222 can be received and evaluated based on the time and channel of reception.

In 1 a motor vehicle 100, for example a ground vehicle such as a passenger car (car), a goods transport vehicle (van, truck) or an agricultural machine is shown. In the non-limiting example of 1 the motor vehicle 100 has an electronic control unit 102 that could implement the control unit and the evaluation unit of an ultrasonic measuring unit as functions. To implement these functions, the control unit 102 could, for example, have a specialized chip that has hard-coded program instructions that the chip executes to cause the control unit 102 to implement the functions of the control unit and the evaluation unit; or the control unit 102 could, for example, have a generic processor that, when the control unit 102 is initialized, loads program instructions from a memory that the processor executes to cause the control unit 102 to perform the functions of the control unit and the evaluation unit. A power source 110 (e.g. a battery and/or an alternator) of the motor vehicle 100 could provide electrical energy in order to be able to use the components connected to the control unit 102 as described below.

The motor vehicle 100 has several ultrasonic transducers 130, which are connected to an interface of the control unit 102 via an analog or digital electrical line system 112, for example. The control unit 102 could perform the function of the control unit via the line system 112 in order to control one or more of the ultrasonic transducers 130 to alternately transmit ultrasonic signals on different channels. Echoes of the transmitted ultrasonic signals received by one or more of the ultrasonic transducers 130 could be converted into electrical signals by the ultrasonic transducers 130 and transmitted to the control unit 102 via the line system 112. The control unit 102 could perform the function of the evaluation unit in order to evaluate the signals corresponding to the received echoes in order to detect at least one object causing the echoes.

Further components of the motor vehicle 100 could be connected to the interface of the control unit 102. For example, a bus system 114 (e.g. a controller area network, CAN) could connect a steering control 104, a human-machine interface 106 (e.g. a touchscreen display) and a brake control 108 to the control unit 102. The control unit 102 could be designed to generate and/or adapt specific signals for the steering control 104, the human-machine interface 106 and/or the brake control 108 depending on an evaluation result of the ultrasonic echoes provided by the evaluation unit, and/or to control and/or adapt the function of the control unit and/or the evaluation unit in response to user interaction with the human-machine interface 106. In another example, an analog or digital electrical line system 116, 118 could connect a set of control elements 124 and a set of output units 126 (e.g. loudspeakers) to the control unit 102. The control unit 102 could be designed to generate and/or adapt specific signals for the output units 126 depending on an evaluation result of the ultrasonic echoes provided by the evaluation unit, and/or to control and/or adapt the function of the control unit and/or the evaluation unit in response to user interaction with the control elements 124.

The 2 shows a schematic representation of snapshots of a motor vehicle 200 with an ultrasonic measuring unit at different times of sending ultrasonic signals 210, 220 and receiving echoes 212, 214, 222 of the sent ultrasonic signals. In 2A the ultrasonic measuring unit has caused an ultrasonic transducer to send a first ultrasonic signal 210 on a first channel, e.g. with a first frequency. There are two obstacles in the detection area from which the ultrasonic measuring unit can receive echoes of ultrasonic signals via one or more ultrasonic transducers within the limits determined by the measurement sensitivity and, if applicable, the duration of a measurement cycle. The obstacle 204 is further away from the motor vehicle 200 than the obstacle 202.

To the 2A At the time shown, the first ultrasonic signal 210 has spread to the nearer obstacle 202 and to the farther obstacle 204 and a first ultrasonic signal reflected from the nearer obstacle 202 in the direction of the motor vehicle 200 The echo 212 of the first ultrasonic signal 210 has just reached one of the ultrasonic transducers. Thus, the evaluation unit can 2A detect the obstacle 202 by evaluating a signal corresponding to the first echo 212 of the first ultrasonic signal 210. The obstacle 204 has been 2A no ultrasonic echo has yet been reflected in the direction of the motor vehicle 200.

2 B shows the motor vehicle 200 and the obstacles 202, 204 at a later time. In 2 B the ultrasonic measuring unit has caused the same ultrasonic transducer to send a second ultrasonic signal 220 on a second channel, eg with a second frequency. The two obstacles 202, 204 are still in the detection range of the ultrasonic measuring unit and the obstacle 204 is still further away from the motor vehicle 200 than the obstacle 202. 2 B At the time shown, the second ultrasonic signal 220 was reflected by the closer obstacle 202 (echo 222). Thus, the evaluation unit can 2 B detect the obstacle 202 by evaluating a signal corresponding to the echo 222.

In 2 B In the meantime, the ultrasonic signal 210 was reflected from the obstacle 204 as a second echo 214. Thus, the evaluation unit can be used to 2 B The obstacle 204 can be detected at the time shown by evaluating a signal corresponding to the second echo 214. This principle described with respect to a single ultrasonic transducer can also be transferred to several ultrasonic transducers, as shown schematically in 2A and 2 B shown as triangles.

3 shows a block diagram of an exemplary ultrasonic measuring unit 300. The ultrasonic measuring unit 300 has a control unit 310 and an evaluation unit 320. The control unit 310 has an output via which the control unit 310 can send a signal 312 to one or more ultrasonic transducers, which causes the ultrasonic transducer(s) to alternately send ultrasonic signals on different channels. The control unit 310 can have an interface for connection to a signal line 311, via which the control unit 310 can exchange signals (e.g. signals for controlling and/or configuring functions of the control unit 310, signals for transmitting outputs of the control unit 310 such as status information, etc.) with other units. The control unit 310 can also have an interface for connecting to a signal line 313, via which the control unit 310 can exchange signals (e.g. time synchronization signals, trigger signals or other control signals) with the evaluation unit 320. The evaluation unit 320 has an input via which the evaluation unit 320 can receive a signal 314 from one or more ultrasonic transducers that corresponds to an ultrasonic signal received by the ultrasonic transducer(s) (e.g. an echo of the ultrasonic signals). The evaluation unit 320 can also have an interface for connecting to a signal line 316, via which the evaluation unit 320 can exchange signals (e.g. signals for controlling and/or configuring functions of the evaluation unit 320, signals for transmitting outputs of the evaluation unit 320 such as status information and/or information about obstacles detected by means of the received signals such as a distance of an obstacle closest to the transmitting ultrasonic transducer, etc.) with other units. The evaluation unit 320 can also have an interface for connection to the signal line 313, via which the evaluation unit 320 can exchange signals (e.g. time synchronization signals, trigger signals or other control signals) with the control unit 310.

4 shows a block diagram of an ultrasonic measuring unit 400. The ultrasonic measuring unit 400 has a control unit 410, an evaluation unit 420 and one or more ultrasonic transducers 415, as shown, for example, in the 2A and 2 B are used. The control unit 410 has an output via which the control unit 410 can send a signal 412 to one or more of the ultrasonic transducers 415, which causes the ultrasonic transducer(s) 415 to alternately send ultrasonic signals on different channels. The design of the control unit 410 and the evaluation unit 420 including signal line 411, interface 413 and signal line 416 can be determined by the 3 (there reference numerals 310, 320, 311, 313 and 316).

The evaluation unit 420 has an input via which the evaluation unit 420 can receive a signal 414 from one or more of the ultrasonic transducers 415, which corresponds to an ultrasonic signal received by the ultrasonic transducer 415 (e.g. an echo of the ultrasonic signals). The one or more ultrasonic transducers 415 can have an interface for receiving a signal 412 from the control unit 410 and for sending a signal 414 to the evaluation unit 420, a transmitter device for generating ultrasonic signals depending on the received signal 412 and, for example, a receiver device for amplifying received ultrasonic signals and generating the signal 414 depending on the received ultrasonic signals.

The 5 shows a flow chart with steps of a method 500 as it can be implemented by an ultrasonic measuring unit disclosed herein. The method 500 provides that the ultrasonic measuring unit controls 502 one or more ultrasonic transducers by means of its control unit in order to alternately send ultrasonic signals on different channels. The method 500 further comprises a step 504 in which the evaluation unit of the ultrasonic measuring unit evaluates signals resulting from the echoes sent alternately on the different channels in order to detect at least one object causing the echoes. Successful execution of step 504 requires that step 502 has been executed at least once previously in order to generate potential echoes that can be evaluated by the evaluation unit. Apart from that, steps 502, 504 can be executed in any order, repeated and/or parallelized in time.

6 shows a diagram of an example of a time course of the signal amplitude measured by an ultrasonic transducer at the beginning of a transmission and reception period on a single channel. The 6 The time and duration values mentioned are for illustrative purposes only and are in no way to be understood as stipulations restricting the invention. The transmission and reception period begins with an excitation of the oscillation unit (e.g. the membrane) of the ultrasonic transducer to transmit an ultrasonic signal at time t = 0. The excitation signal emitted by the control unit of the ultrasonic measuring unit, which causes the excitation unit (e.g. the piezo element) of the ultrasonic transducer to excite the oscillation unit from t = 0, is terminated after a predetermined excitation period 602 (e.g. 250 µs) has elapsed. After the excitation signal has ended, the oscillation unit continues to oscillate for a decay period 604 with a known nominal value (e.g. 1 ms) until the measured amplitude falls below a known or continuously updated noise level. The sum of the excitation period 602 and the decay period 604 forms the transmission period 606 for the given channel (e.g. 1.25 ms). The transmission period 606 is followed by a reception period 610, the duration of which (e.g. 30 ms) is large compared to the duration of the transmission period and the end of which therefore occurs in the 6 is not shown. In the reception period 610, no transmission operations are planned on any of the channels implemented by the ultrasonic measuring unit. The transmission period 606 and the reception period 610 are collectively referred to as the transmission and reception periods.

At a point in time (shown as the transit time 608 from t = 0) after the end of the transmission period 606, a first echo of the ultrasonic signal transmitted in the transmission period 606 arrives at the ultrasonic transducer. It causes an increase in amplitude, which the evaluation unit of the ultrasonic measuring unit detects, for example, by comparing it with a predetermined threshold value representing a maximum assumed noise level. From the transit time Δt 608 and the speed of sound c, the evaluation unit can determine the distance d = cΔt/2 of the obstacle that caused the echo received after the transit time 608.

The 7 shows a timeline on which different time periods of a measuring cycle 700 are marked. The measuring cycle 700 is divided into a first transmission and reception period 710 and a second transmission and reception period 720. In the example of 7 , but without limiting the generality, the first transmission and reception period 710 and the second transmission and reception period 720 are of equal length. The first transmission and reception period 710 is divided into a first transmission period 712 and a first reception period 714; the second transmission and reception period 720 is divided into a second transmission period 722 and a second reception period 724. In the example of 7 , but without loss of generality, the first transmission period 712 and the second transmission period 722 are of equal length and the first reception period 714 and the second reception period 724 are of equal length. In another non-limiting example, the measurement cycle 700 has a duration of 50 ms, which is divided into a first transmission period of 1.4 ms, a first reception period of 23.6 ms, a second transmission period of 1.4 ms, and a second reception period of 23.6 ms.

The measuring cycle 700 can be repeated with the same or different durations of the individual transmission periods and reception periods. The ultrasonic measuring unit implementing the measuring cycle 700 is configured to control the ultrasonic transducer to alternately transmit ultrasonic signals on different channels. In the 7 In the example shown, the ultrasonic measuring unit uses its control unit to control the ultrasonic transducer during the first transmission period 712 to transmit a first ultrasonic signal on a first channel and during the second transmission period 722 to transmit a second ultrasonic signal on a second channel.

Analogous to the description of the 6 In the first reception period 714, the evaluation unit of the ultrasonic measuring unit can evaluate signals on the first channel that are echoes received by an ultrasonic transducer of the signal received during the first transmission. period 712 in order to detect one or more objects causing the echoes in a close range. Optionally, during the first reception period 714 the evaluation unit additionally evaluates signals which correspond to echoes received by an ultrasonic transducer of a second ultrasonic signal sent on the second channel during the second transmission period 722 of an earlier measurement cycle 700 in order to detect one or more further objects causing the echoes in a first long-distance range. Also optionally, during the first reception period 714 the evaluation unit additionally evaluates signals which correspond to echoes received by an ultrasonic transducer of a first ultrasonic signal sent on the first channel during the first transmission period 712 of an earlier measurement cycle 700 in order to detect one or more further objects causing the echoes in a second long-distance range which is further away from the transmitting ultrasonic transducer than the first long-distance range. The evaluation unit can distinguish echoes arriving on the same channel from a previous measuring cycle 700 from ultrasonic signals sent in the current measuring cycle 700 based on their maximum amplitude when the time course of the maximum amplitude of ultrasonic echoes is known.

In the second reception period 724, the evaluation unit of the ultrasonic measuring unit evaluates signals on the second channel that correspond to echoes received by an ultrasonic transducer of the second ultrasonic signal transmitted during the second transmission period 722 in order to detect one or more objects causing the echoes in a further close range. In addition, during the second reception period 724, the evaluation unit evaluates signals that correspond to echoes received by an ultrasonic transducer of a first ultrasonic signal transmitted on the first channel during the first transmission period 712 of the current measuring cycle 700 in order to detect one or more further objects causing the echoes in a further first far range. Optionally, during the second reception period 724, the evaluation unit additionally evaluates signals that correspond to echoes received by an ultrasonic transducer of a second ultrasonic signal transmitted on the second channel during the second transmission period 722 of an earlier measurement cycle 700 in order to detect one or more further objects causing the echoes from a further second long-distance area. After the end of the second reception period 724, a new measurement cycle 700 with a further first transmission period 712 can follow.

It should be noted that the embodiments of the invention described herein can be combined with each other in any way, as long as the combination of two specific embodiments is not excluded for technical reasons.

List of reference symbols

100

Motor vehicle

102

Control unit

104

Steering control

106

Human-machine interface

108

Brake control

110

Power source

112

Pipeline system

114

Bus system

116

Pipeline system

118

Pipeline system

124

Control element

126

Output unit

130

Ultrasonic transducer

200

Motor vehicle

202

obstacle

204

obstacle

210

first ultrasound signal

212

first echo of the first ultrasound signal

214

second echo of the first ultrasound signal

220

second ultrasound signal

222

Echo of the second ultrasound signal

300

Ultrasonic measuring unit

310

Control unit

311

Signal line

312

outgoing signal

313

Signal line

314

incoming signal

316

Signal line

320

Evaluation unit

400

Ultrasonic measuring unit

410

Control unit

411

Signal line

412

outgoing signal

413

Signal line

414

incoming signal

415

Ultrasonic transducer

416

Signal line

420

Evaluation unit

500

Method for operating an ultrasonic measuring unit

502

Control to send

504

Evaluate to detect

602

Excitation duration

604

Swing-out time

606

Broadcast period

608

Duration

610

Reception period

700

Measuring cycle

710

first transmission and reception period

712

first broadcast period

714

first reception period

720

second transmission and reception period

722

second broadcast period

724

second reception period

Claims (12)

Ultrasonic measuring unit (300, 400), in particular for use in a vehicle (100, 200), comprising a control unit (310, 410) and an evaluation unit (320, 420), wherein - the control unit (310, 410) is designed to control (502) an ultrasonic transducer (130, 415) for alternately transmitting ultrasonic signals (210, 220) on different channels, - the evaluation unit (320, 420) is designed to evaluate (504) echoes (212, 214, 222) resulting from the ultrasonic signals (210, 220) on the channels for detecting at least one object (202, 204) causing the echoes. Ultrasonic measuring unit (300, 400) according to Claim 1 , wherein the control (502) and evaluation (504) takes place in a measuring cycle (700), wherein the measuring cycle (700) is carried out cyclically. Ultrasonic measuring unit (300, 400) according to Claim 2 , wherein within the measuring cycle (700) the ultrasonic signals comprise at least a first ultrasonic signal (210) on a first channel and a second ultrasonic signal (220) on a second channel. Ultrasonic measuring unit (300, 400) according to Claim 3 , wherein the evaluation (504) takes into account echoes (212) resulting at least on the first channel between the transmission of the two ultrasonic signals (210, 220), and the evaluation takes into account echoes (212, 214, 222) resulting on the first and second channels after the transmission of the second ultrasonic signal (220). Ultrasonic measuring unit (300, 400) according to Claim 3 or 4 , wherein a maximum spatial measuring distance is defined for the ultrasonic measuring unit (300, 400), wherein the length of the measuring cycle (700) is set such that an echo (212, 214) resulting from the first ultrasonic signal (210), which is caused by an object (202, 204) located at the maximum measuring distance, can be detected within the measuring cycle (700). Ultrasonic measuring unit (300, 400) according to one of the previous Claims 2 - 5 , wherein the evaluation unit (320, 420) is designed to continuously evaluate echoes (212, 214, 222) resulting from the ultrasonic signals (210, 220) on all channels within the measuring cycle (700). Ultrasonic measuring unit (300, 400) according to one of the preceding claims, wherein the evaluation unit (320, 420) is designed to receive the echoes (212, 214, 222) from the same ultrasonic transducer (130, 415) from which the ultrasonic signals (210, 220) were sent. Ultrasonic measuring unit (300, 400) according to one of the previous Claims 2 - 7 , wherein the different channels comprise at least three channels, wherein within the measuring cycle (700) the transmission of the successive ultrasonic signals (210, 220) takes place at different time intervals, wherein the different time interval is constant for the cyclically repeating execution of the measuring cycle (700). Ultrasonic measuring unit (300, 400) according to one of the previous Claims 2 - 7 , wherein during the cyclically repeated execution of the measuring cycle (700), the transmission of the successive ultrasonic signals (210, 220) takes place at different time intervals for at least some of the measuring cycles (700). Ultrasonic measuring unit (300, 400) according to one of the preceding claims, further comprising the ultrasonic transducer (415), wherein the ultrasonic transducer (415) is designed to receive the echoes (212, 214, 222) resulting from the ultrasonic signals (210, 220) on all channels and to transmit them to the evaluation unit (320, 420). Method (500) for operating an ultrasonic measuring unit (300, 400), in particular for use in a vehicle (100, 200), wherein the ultrasonic measuring unit (300, 400) comprises a control unit (310, 410) and an evaluation unit (320, 420), wherein the method (500) comprises: - by the control unit (310, 410), controlling (502) an ultrasonic transducer (130, 415) for alternately transmitting ultrasonic signals (210, 220) on different channels, - by the evaluation unit (320, 420), evaluating (504) echoes (212, 214, 222) resulting from the ultrasonic signals (210, 220) on the channels for detecting at least one object causing the echoes (212, 214, 222) (202, 204). Computer program product, in particular a computer-readable storage medium, wherein the computer program product comprises computer-executable code, wherein the code is executable by at least one processor of a computer device (102) to cause the computer device (102) to carry out the method (500) according to Claim 11 to carry out.

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