Vertically resolved obstacle profiling using ultrasound

Abstract

The present invention relates to a method for generating a vertically resolved obstacle profile (118) for a vehicle (100) using ultrasound, the method comprising the steps of: recording (S2) a number of echo curves received in response to transmitting (S1) respective transmit signals, the transmit signals being generated at different ultrasonic frequencies using an ultrasonic transducer (108) having frequency-based transmit characteristics; providing (S3) a description of the transmit characteristics of the ultrasonic transducer (108) for each of the ultrasonic frequencies, the description assigning transmit strengths to a number of transmit angles (122) in a vertical plane; identifying (S4) the transmit angles (122) and obstacle distances (120) for each of the signals included in the echo curves by comparing the receive strength difference of the signals between at least two echo curves with the transmit strength difference between the signal characteristics, where the ultrasonic frequency is the ultrasonic frequency of the transmit signal; and generating an obstacle profile by combining the identified transmit angles with their corresponding obstacle distances (S7).

Description

[Technical Field]

[0001] The present invention relates to a method for constructing a vertically resolved obstacle profile for a vehicle using ultrasound, and further to a control device, an ultrasonic transducer, and a vehicle. [Background technology]

[0002] It is necessary to identify the vertically resolved profile of an obstacle located ahead of the vehicle in the direction of travel. One practical application may be forward parking into a parking space with a ventilation duct attached to the ceiling. For example, if the vehicle being parked has a long, narrow hood, as in the case of a sedan or station wagon, the hood may occupy the space directly below the ventilation duct, thereby utilizing the entire length of the parking space. However, in this example, if the ventilation duct is incorrectly identified as an obstacle, an obstacle warning may be triggered, which may upset and / or distract the driver. Another application may be distinguishing between a curb that can be overcome and a wall that cannot be overcome.

[0003] U.S. Patent Application Publication No. 2020 / 0201347A1 discloses a self-propelled device having a housing, a movement module, a drive module, and a control module. The movement module is designed to drive the housing, and the drive module is designed to drive the movement module to move. The control module is designed to control the self-propelled device. A sensor assembly for non-contact obstacle identification is disposed in the housing. After the obstacle identification sensor assembly detects that an obstacle is in the movement direction, the control module controls the self-propelled device to continue and control movement until the obstacle is avoided, the movement direction being the forward direction of the self-propelled device. Using the example of an autonomous lawnmower, it is explained that only obstacles within a certain height range can be detected, and that different viewing directions of the ultrasonic sensor can be determined by different mounting heights and tilt angles.

[0004] Accordingly, using multiple ultrasonic sensors with different mounting heights and / or tilt angles to obtain a vertically resolved obstacle profile results in a fragmented and expensive system. Summary of the Invention [Problem to be solved by the invention]

[0005] Against this background, it is an object of the present invention to provide an improved approach, and in particular to provide a reliable and inexpensive technique for constructing vertically resolved obstacle profiles. [Means for solving the problem]

[0006] The aforementioned object is achieved by proposing a method for constructing a vertically resolved obstacle profile for a vehicle using ultrasound, the method comprising the steps of: recording a number of echo responses received in response to transmission of respective transmit signals, the transmit signals being generated at different ultrasonic frequencies by an ultrasonic transducer having frequency-dependent transmit characteristics; providing a description of the transmit characteristics of the ultrasonic transducer that assigns transmit intensities to a number of transmit angles in a vertical plane for each of the ultrasonic frequencies; determining the transmit angles and obstacle distances of the signals contained in the echo responses by comparing the receive intensity difference of the signals between at least two echo responses with the transmit intensity difference between the signal characteristics, the ultrasonic frequency of which is the ultrasonic frequency of the transmitted signals; and constructing the obstacle profile by combining the determined transmit angles with their associated obstacle distances.

[0007] This method takes advantage of the fact that ultrasonic transducers can have frequency-dependent transmission characteristics. If an obstacle is not located along the main direction of the ultrasonic transducer, but rather is offset obliquely from the main direction, the transmission strength of the transmit signal emitted to an example obstacle depends on the ultrasonic frequency of the transmit signal. This difference in transmission characteristics can directly result in a difference in the intensity of the ultrasonic echo. If the frequency-dependent transmission characteristics are known, the angle between the main direction and the obstacle can be inferred from the difference in the intensity of the ultrasonic echo. Therefore, it is possible to obtain a vertically resolved obstacle profile without additional ultrasonic sensors.

[0008] The term vertical plane preferably refers to the rest position of the vehicle in a ready-to-run state on a horizontal plane. The vertical plane is preferably a plane perpendicular to the current surface below the vehicle. If the vehicle moves over an uneven surface, the vertical plane may not be vertical. However, this effect is typically negligible in conventional road surface situations given the spatial resolution achieved by ultrasonic sensors. The ultrasonic sensor, ultrasonic sensors, and / or each ultrasonic sensor used in this method is preferably mounted to the vehicle in a manner that secures it to the vehicle body.

[0009] The term vertically resolved obstacle profile preferably refers to an aggregation of respective distances from obstacles at multiple heights. The obstacle profile may include no obstacles detected at one or more heights. The vertically resolved obstacle profile is preferably constructed for a vertical plane.

[0010] Options and aspects that offer advantages over the basic form of the proposed method and thus further improve the method are outlined below. The presented options and aspects may be combined.

[0011] According to a preferred option, the step of determining the transmission angle and obstacle distance comprises the following steps for a number of recorded echo responses: identifying a test signal by comparing a first echo response recorded at a first ultrasonic frequency with a second echo response recorded at a second ultrasonic frequency, the test signal having a reception intensity difference between the first and second echo responses; and identifying a transmission angle corresponding to the test signal in the vertical plane if the reception intensity difference corresponds to a transmission intensity difference between the transmission intensity of the first ultrasonic frequency at a transmission angle and the transmission intensity of the second ultrasonic frequency at that transmission angle. In other words, a transmission angle corresponding to the test signal is identified in the vertical plane if the reception intensity difference corresponds to a transmission intensity difference between the transmission intensity of the first ultrasonic frequency at a transmission angle and the transmission intensity of the second ultrasonic frequency at that transmission angle.

[0012] According to one option, a first test signal included in a first echo response corresponds to a second test signal included in a second echo response if the propagation time of the first signal differs from the propagation time of the second signal by no more than 10%, preferably no more than 7%, and preferentially no more than 4%. These tolerances allow for taking into account different reflection points on an obstacle. As a result, the method can, for example, correctly identify a large area of ​​obstacles as an obstacle.

[0013] According to one option, a difference in received power corresponds to a difference in transmitted power if it differs from the difference in transmitted power by no more than 35%, preferentially no more than 25%, more preferentially no more than 12.5%. In this way, the method can reliably identify obstacles, for example, that have frequency-dependent and / or large-scale, widely dispersed reflection behavior.

[0014] According to another option, the transmitted signal is transmitted using an ultrasonic transducer having a main axis extending downward, horizontally, and / or up to 20° upward from the ultrasonic transducer in the radiation direction. Thus, the method can be implemented using ultrasonic transducers that could previously be customarily installed in vehicles to identify obstacles. The indicated direction can preferably relate to a vehicle that is stationary, for example, unladen and ready to move, on a horizontal surface.

[0015] According to another option, the same ultrasonic transducer is used to transmit the transmission signal and to receive the echo response. This means, for example, that the method can be implemented with less expense. Additionally or alternatively, a different ultrasonic transducer is used to receive the echo response than to transmit the transmission signal. This makes it possible, for example, to identify obstacles directly in front of the vehicle. In addition, for example, obstacles laterally offset relative to the ultrasonic transducer emitting the transmission signal can be reliably identified, especially if the receiving ultrasonic transducers are laterally offset in the same direction. If multiple horizontally distributed ultrasonic transducers are used for reception, obstacles can be detected in space using multiple vertically resolved obstacle profiles. Preferably, multiple, at least horizontally distributed, ultrasonic transducers are used to receive the respective echo responses. It is preferable if the following steps are performed for each ultrasonic transducer: recording multiple echo responses and determining the transmission angle and obstacle distance of the signal contained in the echo response.

[0016] According to another option, the method can include the following step: determining the horizontal position of an obstacle by evaluating the propagation time difference of test signals received by a number of at least horizontally distributed ultrasonic transducers. For example, by knowing the relative positions of the ultrasonic transducers that received the test signal or the ultrasonic transducers that transmitted and / or received the transmitted signal, the obstacle that reflected the test signal can be identified in space. Thus, the driver can be provided with even better information about where the obstacle is located.

[0017] If multiple obstacle profiles are constructed, the method can be extended to combine the individual obstacle profiles into a three-dimensional obstacle profile, which may be particularly suitable for overlaying and / or comparison with scanning results from, for example, laser scanners, image recognition, and / or three-dimensional maps.

[0018] Based on different echo responses, different transmission angles may be assigned to the test signal. This may be caused, for example, by frequency-dependent reflection behavior. This phenomenon may occur when a single ultrasonic transducer transmits and receives; when one ultrasonic transducer transmits and another ultrasonic transducer receives; when one ultrasonic transducer transmits and this ultrasonic transducer and at least one other ultrasonic transducer receive; or when one ultrasonic transducer transmits and multiple other ultrasonic transducers receive. For example, in all of these cases, the location of the obstacle may be determined with greater accuracy by a method that includes determining the minimum, average, or maximum transmission angle associated with the test signal in a vertical plane. As a further development, measures may be taken to determine the minimum for transmission angles above the main axis of the transmitting ultrasonic transducer, for example, for transmission angles above the main axis of more than 30°. Additionally or alternatively, a further development can be provided in which the average is determined for transmission angles close to the main axis of the transmitting ultrasonic transducer, for example, for transmission angles ranging from 30° above the main axis to 10° below the main axis. A further development can be provided in which the maximum is determined for transmission angles below the main axis of the transmitting ultrasonic transducer, for example, for transmission angles less than 10° below the main axis. These developments are advantageous, for example, in vehicles in which the ultrasonic transducer is mounted in the most protruding body part. These developments ensure that the location of the obstacle closest to the ultrasonic transducer is determined for safety reasons.

[0019] It may be the case that an ultrasonic transducer has a frequency-dependent reception characteristic, the magnitude of which is relevant to the accuracy of the proposed method. In this case, to obtain better accuracy, one proposed option is for the method to include a step of providing a description of the reception characteristic of the or each ultrasonic transducer used to receive multiple echo responses for each ultrasonic frequency, where each reception characteristic describes the reception strength of a transmitted pulse for different reception angles in the vertical plane. Furthermore, it is proposed that each echo response is processed by filtering using the respective reception characteristic. Alternatively, the description of the reception characteristic may be combined with a description of the transmission characteristic, and this combination may be provided for the or each receiving ultrasonic transducer.

[0020] For example, to facilitate signal processing of the method and / or, for example, to efficiently parallelize the method, measures can be taken such that the ultrasonic transducers transmit the transmit signals in order of ultrasonic frequency. It is particularly preferred that the transmit signals are in ascending order of ultrasonic frequency, thus starting with the lowest ultrasonic frequency, which typically has the widest transmit angle. Furthermore, it is particularly preferred that the method be performed consecutively and / or repeatedly, with the transmit signal at the highest ultrasonic frequency followed by the transmit signal at the lowest ultrasonic frequency.

[0021] This method is particularly suitable for facilitating maneuvering in tight spaces such as car parks or parking spaces. It is therefore advantageous, by way of example, if the method is only performed up to a specified maximum speed in order to save energy. By way of example, this maximum speed may be up to 50 km / h, or more preferentially up to 30 km / h.

[0022] It is further proposed a computer program product comprising instructions which, when executed by a computer, cause said computer to carry out the method described above, the computer product having the features and advantages of the method performed or capable of being performed.

[0023] The computer program product, e.g. computer program means, may for example be provided or supplied as a storage medium, e.g. a memory card, USB stick, CD-ROM, DVD, or in the form of a file downloadable from a server in a network, e.g. by transmitting the computer program product or a corresponding file containing the computer program means in a wireless communication network.

[0024] The object stated at the outset is achieved by proposing a control device for a vehicle. The control device can be coupled to at least one ultrasonic transducer, including a group of matched ultrasonic transducers, for information transmission. For example, the control device can be coupled to the at least one ultrasonic transducer via a bus. The control device is configured to execute the above-mentioned method, preferably in the form of the above-mentioned computer program product. The control device has the features and advantages of the method that it executes or is capable of executing.

[0025] Furthermore, the proposed control device may also be part of a higher-level control system of the vehicle, for example in the form of a central electronic control device and / or an engine control device (ECU: Engine Control Unit).

[0026] The control device may include recording means, such as, for example, a volatile memory and / or an interface, in particular for recording a large number of echo responses. The control device may include storage means, such as, for example, a volatile or non-volatile memory, in particular for providing the transmission characteristics of the ultrasonic transducer for each of the ultrasonic frequencies. The control device may include execution means, such as, for example, a processor, in particular for determining the transmitted signal and obstacle distance in each case and for building an obstacle profile.

[0027] Each means may be implemented in hardware and / or software. In the case of a hardware implementation, each means may be, for example, in the form of a computer or a microprocessor. In the case of a software implementation, each means may be in the form of a computer program product, a function, a routine, an algorithm, a portion of program code or an executable object.

[0028] The object stated at the beginning is achieved by proposing an ultrasonic transducer for a vehicle. The ultrasonic transducer is configured to perform the above-mentioned method. To realize some of the options and / or aspects of the above-mentioned method, the ultrasonic transducer may optionally be configured to be capable of being coupled to at least one ultrasonic transducer that comprises part of a group of matched ultrasonic transducers for information transmission. The proposed ultrasonic transducer has the features and advantages of the method that is performed or can be performed.

[0029] The ultrasound transducer may include, inter alia, ultrasound transducer means, recording means, storage means, and / or execution means.

[0030] Finally, the object mentioned at the outset is also achieved by proposing a vehicle having at least the aforementioned control device and / or the aforementioned ultrasonic sensor, the vehicle having the features and advantages of the method, the control device and / or the ultrasonic transducer that are implemented or can be implemented.

[0031] If both a control device and an ultrasonic sensor are present, the method steps may be performed in a distributed manner across the ultrasonic sensors and the control device. The same applies to multiple ultrasonic sensors and / or multiple control devices.

[0032] Further possible implementations of the present invention further include not explicitly mentioned combinations of the features or embodiments described above or below with respect to the exemplary embodiments, in which case the skilled person will further add individual aspects as improvements or additions to the respective basic form of the invention.

[0033] Further advantageous configurations and aspects of the invention form the subject matter of the dependent claims and of the exemplary embodiments of the invention described below. The invention is explained in more detail below on the basis of preferred embodiments with reference to the accompanying drawings. [Brief explanation of the drawings]

[0034] [Figure 1] 1 is a schematic plan view of an exemplary vehicle having multiple ultrasonic sensors and a control device; [Figure 2] 1 is a schematic side view of a vehicle having an ultrasonic sensor, the vehicle performing a method according to a first embodiment of the invention; [Figure 3] 1A-1D are schematic side views of steps of a method according to a first embodiment of the present invention; [Figure 4] 1 is a schematic flow diagram of a method according to a first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0035] Identical or functionally identical elements are represented by the same reference numbers in the figures unless otherwise noted.

[0036] 1 shows a schematic bird's-eye view of a vehicle 100. The vehicle 100 is, for example, a car arranged in a surrounding 102. The car 100 has a control device 104 which includes, for example, a parking assistance system.

[0037] Additionally, multiple environmental sensor devices 106, 108 may be disposed on the vehicle 100, such as optical sensors 106 and ultrasonic sensors 108. The optical sensors 106 may include, for example, a visual camera, radar, and / or lidar. Each of the optical sensors 106 may capture an image of a respective area from the surroundings 102 of the vehicle 100 and output the image as an optical sensor signal. The ultrasonic sensors 108 may detect the distance from an object disposed in the surroundings 102 and output a corresponding sensor signal. Using the sensor signals captured by the sensors 106, 108, the control device 104 may, for example, drive the vehicle 100 partially autonomously or fully autonomously. In addition to the optical sensors 106 and ultrasonic sensors 108 shown in FIG. 1, the vehicle 100 may include various other sensor devices 106, 108. Examples of these include microphones, acceleration sensors, antennas with coupled receivers for receiving electromagnetically transmittable data signals, etc.

[0038] 2 shows a side view of the vehicle 100, showing one of the ultrasonic sensors 108. The ultrasonic transducer 108 has a horizontally extending major axis H. The surroundings 102 include an obstacle 110, which has a profile 112 facing the vehicle.

[0039] The method according to the invention is explained below using the flow chart of FIG.

[0040] This method has a number of sub-steps S1-1 to S1-4, which are collectively referred to as step S1. This method also has a number of sub-steps S2-1 to S2-4, which are collectively referred to as step S2.

[0041] In a first substep S1-1, the ultrasonic transducer 108 transmits a transmission signal 114-1 at an ultrasonic frequency. Subsequently, in substep S2-1, an echo response is recorded by the ultrasonic transducer 108 and the control device 104. When the transmission signal 114 hits an obstacle 110, a reflected signal is reflected back to the ultrasonic transducer 108 and recorded in the echo response. Along with the echo response, the ultrasonic frequency of the transmission signal is recorded.

[0042] Substep S2-1 is followed by substep S1-2, in which transmit signal 114-2 is transmitted, in which an echo response is recorded in substep S2-2.

[0043] In this manner, in substeps S1-1 to S1-4, transmission signals 114-1 to 144-4 are repeatedly transmitted, and in each of substeps S2-1 to S2-4, echo responses are recorded.

[0044] In the first embodiment, for example, four different ultrasound frequencies are used, and for each ultrasound frequency, the method comprises a substep S1 for transmitting and a substep S2 for recording the respective echo response.

[0045] As symbolically depicted in the depiction of FIG. 2, the ultrasonic transducer 108 has frequency-dependent transmission characteristics. For clarity, each of the four transmit signals 114-1 through 114-4 is represented by a circular sector. The circular sector representing the lowest ultrasonic frequency transmit signal 114-1 has the largest central angle. Furthermore, the circular sector representing the highest ultrasonic frequency transmit signal 114-4 has the smallest central angle. The circular sectors represent the range of high transmit intensity for each transmit signal 114. The representation as circular sectors is a simplification; in reality, transmit intensity typically does not decrease abruptly but rather decreases gradually as the angle relative to the ultrasonic transducer's primary direction increases. The circular sectors in FIG. 2 are shown with different radii. This is another simplification; in reality, transmit signals 114 of different ultrasonic frequencies have different ranges, but transmit intensity typically does not decrease abruptly but rather decreases gradually as the distance from the ultrasonic sensor 108 increases.

[0046] 2 and 3 show ten reflections 116-1 through 116-10 as an example. Echo responses recorded in response to transmission of transmit signal 114-1 at the lowest ultrasonic frequency include, for example, signals of reflections 116-1, 116-2, 116-8, 116-9, and 116-10. Echo responses recorded in response to transmission of transmit signal 114-2 at the second lowest ultrasonic frequency include, for example, signals of reflections 116-3, 116-7, 116-8, and 116-9. Echo responses recorded in response to transmission of transmit signal 114-3 at the second highest ultrasonic frequency include, for example, signals of reflections 116-6 and 116-7. Echo responses recorded in response to transmission of transmit signal 114-4 at the highest ultrasonic frequency include, for example, signals of reflections 116-4, 116-5, and 116-6.

[0047] In the next step S3, a signal characteristic description of the ultrasonic transducer 108 is provided, for example, for each of four ultrasonic frequencies. Thus, by way of example, four signal characteristic descriptions are provided. Note that the signal characteristic descriptions may be provided as a combined file, a combined table, or a software function or method. Each signal characteristic description assigns a respective transmission strength to a number of transmission angles in the vertical plane. In other words, the transmission characteristic description indicates, for example, the transmission strength distribution of the ultrasonic transducer 108 for each ultrasonic frequency relative to the transmission angle.

[0048] In a next step S4, a transmission angle 118 and an obstacle distance 120 are determined for the signal contained in the echo response based on the description of the transmission characteristics. For this purpose, the method uses at least one comparison of at least one received intensity difference of at least one signal between at least two echo responses and at least one transmitted intensity difference between signal characteristics, the ultrasonic frequency of which is the ultrasonic frequency of the transmitted signal in response to which these at least two echo responses were accurately recorded.

[0049] By way of example, steps S5 and S6 are provided for this purpose.

[0050] In step S5, the test signal is first identified. This is accomplished by comparing a first echo response of the set of recorded echo responses with a second echo response of the set of recorded echo responses. The first echo response is recorded in response to transmitting a transmit signal 114 at a first ultrasonic frequency, and the second echo response is recorded in response to transmitting a transmit signal 114 at a second ultrasonic frequency, the second ultrasonic frequency being different from the first ultrasonic frequency. If the method finds a two-echo response signal with a receive intensity difference between the two echo responses, this signal is a test signal, which will be discussed in more detail below.

[0051] The signal strength may be, for example, the signal strength of the received signal. For example, the echo response may first be post-processed, for example, filtered and / or smoothed, for example, using known methods. For example, artifacts such as ground echoes may be filtered out by an algorithm. The signal strength may correspond, for example, to the amplitude of the peak of the echo response.

[0052] The receive power difference may be expressed in absolute terms, e.g., dB, or e.g., volts. The receive power difference may also be expressed in relative terms, e.g., percent, based on, e.g., the signal amplitude of the echo response at a lower ultrasonic frequency. The transmit characteristic is preferably of the same nature (dB, volts, percent) as the receive power difference to which the transmit power difference is to be compared.

[0053] In step S6, each receive intensity difference is compared to the transmit intensity difference. The receive intensity difference exists, in particular, between two echo responses each received in response to a transmit signal at a particular ultrasonic frequency. Continuing with the example above, these are the first and second ultrasonic frequencies. The transmit characteristics of the first and second ultrasonic frequencies are then compared. For example, for each angle of the transmit characteristics, a check is made to see if the transmit intensity difference for this angle corresponds to the receive intensity difference found in step S5.

[0054] The ultrasonic frequency is preferably in the range of 52 kHz ± 20 kHz, more preferably in the range of 52 kHz ± 12 kHz, more preferably in the range of 52 kHz ± 6 kHz, and most preferably in the range of 52 kHz ± 3 kHz.

[0055] In the check of step S6, if the received intensity difference found in step S5 corresponds to the transmitted intensity difference between the transmitted intensity of the first ultrasonic frequency at a certain transmitted angle and the transmitted intensity of the second ultrasonic frequency at that transmitted angle, then this transmitted angle is identified in the vertical plane as the transmitted angle corresponding to the test signal.

[0056] Step S5 is performed for each signal included in the echo response. Step S6 is performed for each test signal found in step S5. In the example of FIGS. 2 to 4, all 10 reflected signals 116-1 to 116-10 are treated as test signals.

[0057] Thus, the result of steps S5 and S6 is that in the upper step S4 there is a set of values ​​including obstacle distance and transmission angle, or there are multiple such sets of values, or there is no set of values. If the obstacle distance cannot be assigned to a transmission angle, the method ends.

[0058] In the next step S7, an obstacle profile 118 is constructed. This obstacle profile 118 is shown, for example, in Figure 3. The position of the reflection, as indicated by the test signal of reflection 116-2, is calculated from the obstacle distance 120 determined in step S5 and the transmission angle 122 determined in step S6. As a result, ten positions of reflections 116-1 to 116-10 are calculated.

[0059] A preferred optional post-processing step identifies the test signal at road level so that the test signal is not included in the construction of the obstacle profile 118. Hence, reflections 116-8 to 116-10 can be ignored when constructing the obstacle profile 118.

[0060] Constructing the obstacle profile 118 includes, for example, drawing a continuous line through the positions obtained by combining the identified transmit angles (122) with their associated obstacle distances (120).

[0061] A comparison of Figures 2 and 3 shows that the actual obstacle profile 112 in Figure 2 and the constructed or identified obstacle profile 118 in Figure 3 differ slightly from each other. This difference is usually tolerable because methods S1-S7 are preferably performed repeatedly as an obstacle is approached and because methods S1-S7 are usually used to roughly orient the driver. 3, the vehicle 100, or at least a portion of the vehicle 100, fits under the location of the obstacle 110 that creates the reflection 116-2. Therefore, the obstacle warning device can alert the driver to the approach of the reflection 116-2, for example, without warning of a collision with the location associated with the reflection 116-2. As a result, the driver can move the vehicle 100 closer to the obstacle 110.

[0062] According to a second embodiment, not shown, multiple ultrasonic transducers 108 are used for this method. For example, one ultrasonic transducer 108 is used to transmit a transmission signal 114, and multiple other horizontally distributed ultrasonic transducers 108 are used to receive and record the echo responses. The receiving ultrasonic transducers 108 are therefore arranged around the vertical axis of the vehicle 100 at different angles.

[0063] By way of example, steps S2 and S4-S7 are performed separately for each of the multiple receiving ultrasonic transducers 108. Thus, each of the multiple receiving ultrasonic transducers 108 is prepared to record multiple echo responses in step S3, determine multiple transmit angles and obstacle distances in multiple passes in steps S4-S6, and then determine a respective obstacle profile 118 in step S7.

[0064] This means that multiple obstacle profiles 118 are determined, each of which is associated with a vertical plane. Thus, by way of example, the control device 104 can better alert the driver of the vehicle 100 to obstacles in the surroundings 102 if the vertical plane is known.

[0065] In one variant, step S7 is performed collectively for all sets of values ​​of all ultrasonic transducers 103, rather than for each individual receiving ultrasonic transducer 108, in order to arrive directly at the three-dimensional obstacle profile 118.

[0066] In a variation of this embodiment, a combined obstacle profile is constructed in a next step from multiple obstacle profiles 118. It would therefore be a three-dimensional obstacle profile. This three-dimensional obstacle profile can be used, for example, for comparison with a stored three-dimensional model of the parking lot and / or with an image or model of the surroundings 102 acquired by the optical sensor 106.

[0067] Although the present invention has been described with reference to exemplary embodiments, the present invention can be varied in many ways. [Explanation of symbols]

[0068] 100 vehicles 102 Surroundings 104 Control Device 106 Optical Sensor 108 Ultrasonic Sensor 110 Obstacles 112 Profiles 114 Transmitted Signal 116 reflection 118 Obstacle Profiles 120 obstacle distance 122 Transmission Angle H spindle

Claims

1. 1. A method for constructing a vertically resolved obstacle profile (118) for a vehicle (100) using ultrasound, comprising: recording (S2) a number of echo responses received in response to transmitting (S1) respective transmit signals, the transmit signals being generated at different ultrasonic frequencies by an ultrasonic transducer (108) having frequency-dependent transmission characteristics; providing (S3) a description of the transmission characteristics of the ultrasonic transducer (108) that assigns a transmission strength for each of the ultrasonic frequencies to a number of transmission angles (122) in a vertical plane; determining (S4) a transmission angle (122) and an obstacle distance (120) of a signal contained in the echo response by comparing a reception strength difference of the signal between at least two echo responses with a transmission strength difference between the signal characteristics, the ultrasonic frequency of which is the ultrasonic frequency of the transmitted signal; constructing an obstacle profile by combining the determined transmission angles with the respective associated obstacle distances (S7); A method comprising:

2. The step (S4) of determining the transmission angle (122) and the obstacle distance (120) comprises: For said number of recorded echo responses, the following steps are performed: a step (S5) of identifying a test signal by comparing a first echo response recorded at a first ultrasonic frequency with a second echo response of the recorded echo responses recorded at a second ultrasonic frequency, the test signal having a receive intensity difference between the first echo response and the second echo response; identifying (S6) a transmission angle (122) corresponding to the test signal in the vertical plane if the received intensity difference corresponds to a transmission intensity difference between the transmission intensity of the first ultrasonic frequency at a transmission angle and the transmission intensity of the second ultrasonic frequency at that transmission angle (122); 2. The method of claim 1, comprising the step of:

3. 3. The method according to claim 1 or 2, characterized in that the transmission signal is transmitted (S1) using an ultrasonic transducer (108) having a main axis (H), the main axis (H) extending downward, horizontally and / or up to 20° upward from the ultrasonic transducer (108) in the radial direction.

4. 4. The method according to claim 1, wherein the ultrasonic transducer (108) transmits the transmission signals in order of ultrasonic frequencies, the transmission signals preferably being in ascending order of ultrasonic frequencies, with the transmission signal at the highest ultrasonic frequency being followed, preferably, by the transmission signal at the lowest ultrasonic frequency.

5. 5. The method according to any one of claims 1 to 4, characterized in that the same ultrasonic transducer (108) is used to transmit the transmit signal (S1) and to receive the echo response.

6. 6. The method according to any one of claims 1 to 5, characterized in that a different ultrasonic transducer (108) is used for receiving the echo response than for transmitting the transmit signal (S1).

7. A number of at least horizontally distributed ultrasonic transducers (108) are used to receive the respective echo responses, and for each ultrasonic transducer (108), the following steps are performed: a step (S2) of recording a number of echo responses; 7. The method according to claim 1, wherein a step (S4) of determining the angle of transmission (122) of the signal contained in the echo response and the obstacle distance (120) is performed.

8. 8. The method according to claim 1, further comprising the step of determining the horizontal position of an obstacle or part of an obstacle reflecting a signal by evaluating the difference in propagation times of test signals received by a number of at least horizontally distributed ultrasonic transducers.

9. The method of claim 8 , further comprising determining a minimum, average, or maximum transmit angle associated with the test signal in the vertical plane.

10. 10. A method for constructing a three-dimensional obstacle profile according to any one of claims 5 to 9, characterized in that the method comprises the step of combining the individual obstacle profiles into a three-dimensional obstacle profile.

11. 11. The method according to claim 1, further comprising providing a reception characteristic of the or each ultrasonic transducer (108) used to receive a number of echo responses for each of the ultrasonic frequencies, each reception characteristic describing the reception strength of a transmitted pulse for different reception angles in a vertical plane.

12. A computer program product comprising instructions that, when executed by a computer, cause the computer to carry out the method of any one of claims 1 to 11.

13. A control device (104) for a vehicle (100) capable of being coupled to at least one ultrasonic transducer (108) for information transmission and configured to perform the method of any one of claims 1 to 11.

14. An ultrasonic transducer (108) for a vehicle (100) configured to perform the method according to any one of claims 1 to 5, preferably coupled to at least one further ultrasonic transducer (108) for information transmission, and capable of being configured to perform the method according to any one of claims 6 to 11.

15. A vehicle (100) comprising a control device (104) according to claim 13 and / or an ultrasonic transducer (108) according to claim 14.

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