Direction-of-travel-dependent setting of a detection range for ultrasonic sensor arrays

Description

[0001] The invention relates to a method for adjusting a detection range of at least one ultrasonic sensor array of a vehicle, a control unit, a computer program and a machine-readable storage medium. State of the art

[0002] Ultrasonic sensors are typically used to monitor the immediate surroundings of a vehicle. These sensors have an optimal range of approximately 5 meters, with each sensor acting as a single source. The beam angle of the sound beam, or the detection range, of common ultrasonic sensors is generally fixed. For reliable ultrasonic distance measurement and object detection, redundant or overlapping measurement of obstacles using multiple ultrasonic sensors is required. However, such overlapping detection ranges of multiple ultrasonic sensors is not possible, particularly when cornering.

[0003] US patent 5,531,117 A discloses the control of a phase shift in a phased array to scatter a resulting ultrasound cone to any desired point. This allows the environment to be scanned.

[0004] From DE 10 2005 024 052 A1, an ultrasound system is known in which the overall viewing angle is controlled based on data from other systems or operating modes, for example depending on the steering angle.

[0005] US 2019 / 033439 A1 describes a system for detecting objects and determining distances based on a phased array. An AI controls the system with respect to beam shaping and the phase shift of the phased array emitters to deflect the detection area. US 2019 / 277962 A1 describes an arrangement of radar sensors that can be configured as a phased array sensor. This allows the transmit and receive directions to be adjusted based on a set phase shift.

[0006] German patent application DE 10 2014 220994 A1 discloses a driver assistance system in which two ultrasonic sensors, each with a fixed detection range, are arranged parallel to each other. The detection ranges of the ultrasonic sensors overlap at their midpoints. This arrangement of the ultrasonic sensors and the resulting detection ranges allows for the accurate detection of a wide variety of situations without requiring any adjustment or swiveling of the detection ranges. Further prior art is known from EP 1 345 044 A1, DE 10 2010 054066 A1, and DE 10 2011 079706 A1. Disclosure of the invention

[0007] The object underlying the invention can be seen as proposing a method by which an ultrasound-based measurement can be dynamically adapted to different traffic situations.

[0008] This problem is solved by means of the respective subject matter of the independent claims. Advantageous embodiments of the invention are the subject matter of dependent claims.

[0009] According to one aspect of the invention, a method for adjusting the detection range of at least one ultrasonic sensor array of a vehicle is provided. The method can preferably be carried out by a control unit alone or in conjunction with corresponding vehicle-side sensors.

[0010] In one step, measurement data is received and a direction of travel is determined by evaluating the measurement data. Subsequently, control signals are generated to control at least two transducer elements of at least one ultrasonic sensor array.

[0011] The control signals are used to set a phase shift between the ultrasonic waves sent by the transducer elements and / or a phase shift between the ultrasonic waves received by the transducer elements, which is adapted to the direction of travel of the vehicle.

[0012] Advantageously, when the vehicle is traveling straight ahead, the detection area of ​​at least one first ultrasonic sensor array is concentrated by a positive phase shift, and the detection area of ​​at least one second ultrasonic sensor array is concentrated by a negative phase shift relative to or away from the vehicle's axis of symmetry. Using this method, multiple ultrasonic sensor arrays mounted on the vehicle can be controlled by the control signals or commands in such a way that the corresponding sensor arrangement is "squinted," meaning the detection areas of the ultrasonic sensor arrays are rotated or deflected towards the sides of the vehicle. This increases the resulting detection area of ​​all ultrasonic sensor arrays.

[0013] Alternatively, the detection areas can be concentrated or focused towards the vehicle's axis of symmetry. This reduces the resulting detection range of all ultrasonic sensor arrays.

[0014] The vehicle's axis of symmetry is defined as an axis directed longitudinally or in the direction of travel, which passes through the vehicle's center, in particular between a driver's seat and a passenger's seat.

[0015] Furthermore, two operating modes can be implemented when positioning the outer, lateral ultrasonic sensor arrays. Specifically, an operating mode for free maneuvering, also known as PAS mode, and an operating mode for parking space search can be implemented. In the "free maneuvering" mode, an overlap of the detection ranges of as many ultrasonic sensor arrays as possible is achieved. Ultrasonic sensor arrays positioned on the outer sides of the vehicle are rotated towards the axis of symmetry so that as many cross-echoes from neighboring sensors as possible can be received.

[0016] In contrast, in the "parking space search" operating mode, the detection range of at least one ultrasonic sensor array can be set perpendicular to the vehicle's movement or adapted to the direction of travel. This allows the front and rear sides of vehicles bordering parking spaces to be illuminated equally.

[0017] Furthermore, beam steering can be used to specifically increase reception sensitivity in high-angle ranges when detecting parking spaces. This results in additional echo signals that can be used via trilateration to improve the localization and classification of the vehicle corner.

[0018] Sidelobes in this form can occur due to the high steering angles of the detection area, particularly in the front of the vehicle. This means that ultrasonic echoes from these areas could be mistakenly interpreted as side echoes, thus distorting the signal evaluation. However, only echoes with a distance of less than the typical passing distance to the side objects (approximately 2-3 meters) are relevant here. At higher speeds (typically more than 10 km / h), ground echoes are the actual source. Therefore, it is advantageous if the receiving characteristic is directed vertically upwards, away from the ground, in addition to the lateral "squint." This could be achieved, for example, with an ultrasonic sensor array with a 2x2 arrangement of transducer elements, where two transducer elements are spaced apart along a transverse direction and two transducer elements are spaced apart along a vertical direction.

[0019] This method allows vehicle-mounted ultrasonic sensor arrays to swivel their detection range horizontally and / or vertically in such a way that the detection area or field of view is aligned with the vehicle's inner tube. The detection ranges of several ultrasonic sensor arrays can be directed at the anticipated inner tube or swivel beyond it.

[0020] The driving tube represents a virtual area which is expected to be crossed or overlaid by the vehicle contour when the vehicle is driving around a curve or straight ahead.

[0021] This method enables intelligent and dynamic control of ultrasonic sensor arrays with respect to the phase shift of the respective transducer elements. By adjusting the phase shift during the generation or reception of ultrasonic waves by the transducer elements, the direction of the detection area, which consists of at least one main lobe, can be set or changed. Thus, by adjusting the phase shift, the detection area can be pivoted or rotated, for example, to dynamically follow the direction of travel of a vehicle. This can increase the localization accuracy and classification in object detection. In particular, the resulting measurement data from the ultrasonic sensor arrays can be used alone or in conjunction with other methods for object detection.

[0022] This method can, for example, improve the control of automatic braking. In particular, the increased number of relevant sensors, which can be "focused" on an area relevant to braking, can enable better plausibility checks of individual results and thus lead to a reduction in misinterpretations.

[0023] Furthermore, the method can be used in the search for parking spaces, where targeted, different control of the individual ultrasonic sensor arrays enables a better characterization of a parking space.

[0024] A control unit can preferably be connected to at least two transducer elements of at least one ultrasonic sensor array via a data conductor. In particular, the control unit can individually control the transducer elements to transmit and / or receive sound waves. The method can be carried out using the control unit.

[0025] The vehicle can be operated in an assisted, semi-automated, highly automated and / or fully automated or driverless manner in accordance with the BASt standard.

[0026] The ultrasonic sensor array of the sensor arrangement has at least two transducer elements spaced apart from each other in the vertical direction and / or in the horizontal direction, wherein the transducer elements and the at least one ultrasonic sensor can be controlled and / or read out by a control unit electrically connected to the transducer elements.

[0027] The individual transducer elements are designed as sub-sensors of the ultrasonic sensor array and can be controlled and evaluated independently of each other by the control unit. In particular, the sound waves generated by the transducer elements can interfere with each other, thereby tilting or deflecting the main axis of the emitted sound echoes relative to the surface normal.

[0028] In particular, by controlling the transducer elements in a phase-shifted manner, for example between vertically offset rows of elements, the main axis of the vertical sound radiation can be tilted relative to the main axis of the sensor membrane.

[0029] Preferably, the transducer elements, which are excited by membrane vibrations and / or cylinder vibrations to generate and receive sound waves, are arranged on a common plane, on the basis of which the surface normal is defined.

[0030] The at least one ultrasonic sensor array can preferably be manufactured using MEMS technology and, for example, configured as a so-called piezoelectric micromachined ultrasonic transducer (PMUT sensor). The transducer elements can be designed as diaphragms, as oscillating pistons, or as combined diaphragm-piston arrangements to generate and / or receive sound pulses or sound waves.

[0031] In one embodiment, the measurement data for determining the direction of travel is received from a unit configured as a parking assistance system, a steering angle sensor, a GNSS sensor, a trajectory planning system, and / or a navigation system. This allows the direction of travel and, furthermore, a predicted travel path of the vehicle to be determined based on a multitude of measurement data. This data can come from a camera system of a parking assistance system, data from a GNSS-based navigation system, or measurement data from various vehicle-mounted sensors.

[0032] According to a further embodiment, the phase shift between the ultrasonic waves transmitted by the transducer elements is adjusted such that a detection range of the at least one ultrasonic sensor array overlaps a vehicle's inner tube. This allows multiple ultrasonic sensor arrays, or just one of several existing ultrasonic sensor arrays, to be configured by the control signals with respect to the orientation of the detection range, such that the inner tube is overlapped by the detection ranges of several ultrasonic sensor arrays.

[0033] Alternatively or additionally, a combination of static or bulk ultrasonic sensors and ultrasonic sensor arrays can be used.

[0034] According to a further embodiment, a vehicle's inner tube is overlapped by the detection range of at least one ultrasonic sensor array in the direction of travel of the vehicle and / or a vehicle's inner tube is overlapped by the detection range of at least one ultrasonic sensor array against the direction of travel of the vehicle. This measure allows ultrasonic sensor arrays to be controlled in any direction in the vehicle's surroundings with respect to the horizontal and / or vertical orientation of the detection range.

[0035] For example, when driving uphill, the detection area at the front of the vehicle can be raised or swiveled away from the ground by the ultrasonic sensor arrays, and at the rear of the vehicle it can be lowered towards the ground to enable optimal detection of obstacles even close to the ground.

[0036] According to a further embodiment, the generated control signals establish a phase shift between the generated ultrasonic waves of at least two transducer elements arranged offset from each other along a transverse and / or vertical direction, wherein the transducer elements are spaced apart in the transverse and / or vertical direction by at least half a wavelength of the generated ultrasonic waves. By arranging the transducer elements at a distance of essentially half a wavelength of the generated ultrasonic waves, the influence of side lobes on the generated ultrasonic waves can be minimized.

[0037] According to a further embodiment, the respective phase shift of transducer elements of the respective ultrasonic sensor array (or at least two ultrasonic sensor arrays) is adjusted by the generated control signals such that the detection ranges of the at least two ultrasonic sensor arrays overlap in the area of ​​the vehicle's inner tube. This allows for the focusing of multiple detection ranges onto the anticipated inner tube.

[0038] Such a focusing of the detection areas can be achieved by rotating or swiveling a detection area of ​​one or more ultrasonic sensor arrays.

[0039] The phase shift of at least one ultrasonic sensor array from a set of multiple ultrasonic sensor arrays can be adjusted by the generated control signals. The phase shift of the other ultrasonic sensor arrays remains unchanged. This reduces the effort required to control the individual ultrasonic sensor arrays, as only a portion of the available arrays need to be controlled by the control unit. Advantageously, regular ultrasonic sensors or bulk ultrasonic sensors can be used instead of uncontrolled ultrasonic sensor arrays.

[0040] According to the claimed invention, control signals are generated to actuate at least two ultrasonic sensor arrays with a different phase shift. Depending on the position of the ultrasonic sensor arrays on the vehicle, the set phase shifts can vary.

[0041] In the following, preferred embodiments of the invention are explained in more detail with reference to highly simplified schematic representations. These show Figs. 1-3 schematic top views of a rear area of ​​a vehicle with visualized phase offset and a resulting detection area according to an embodiment of the invention, Fig. 4 schematic top views of a rear area of ​​a vehicle with an adapted phase angle during straight-ahead driving and cornering according to an embodiment of the invention, Fig. 5 a schematic top view of a rear area of ​​a vehicle with detection areas swiveled away from an axis of symmetry of the vehicle according to an embodiment of the invention, and Fig. 6 a schematic flowchart to illustrate a method according to the invention according to an embodiment.

[0042] In the Figure 1 , the Figure 2 and the Figure 3Schematic top views of vehicle arrangement 1 are shown, illustrating a rear area of ​​a vehicle 2 with a visualized phase shift P and a resulting detection area E behind the vehicle 2 according to embodiments of the invention. In particular, the principle of horizontal beam steering is illustrated by way of example.

[0043] Vehicle 2 features, for example, an ultrasonic sensor array 4. Any number of ultrasonic sensor arrays 4 can be used, arranged symmetrically or asymmetrically along a contour of vehicle 2. Vehicle 2 also features a control unit 8.

[0044] The at least one ultrasonic sensor array can also be arranged analogously in a front area and / or in at least one side area of ​​the vehicle 2.

[0045] The ultrasonic sensor array 4 of the vehicle arrangement 1 has at least two transducer elements 6, 7 spaced apart from each other in the vertical direction z and / or in the transverse direction y and / or in the longitudinal direction x, wherein the transducer elements 6, 7 can be controlled and / or read out by a control unit 8 electrically connected to the transducer elements 6, 7. The control unit 8 can generate control signals or control commands configured to cause the transducer elements 6, 7 to transmit and / or receive ultrasonic waves individually with or without a phase shift P. The two transducer elements 6, 7 are spaced apart along the transverse direction y by a distance corresponding to half a wavelength or lambda / 2 of the generated ultrasonic waves.

[0046] Two converter elements 6, 7 are shown as examples in the diagram to illustrate the relationship between the control of the converter elements 6, 7 and a resulting change in the detection range E.

[0047] In Figure 1 Figure 1 shows a vehicle arrangement in which the control commands generated by the control unit 8 do not establish a phase shift P=0° between the generated ultrasonic waves of the transducer elements 6, 7. As a result, the generated ultrasonic waves propagate perpendicular to the sensor plane or a membrane plane of the transducer elements 6, 7, opposite to the direction of travel. The diagram shows the corresponding ultrasonic pulses of the respective transducer elements 6, 7 with corresponding hatching. The diagram illustrates, based on the transmitted ultrasonic pulses, that no phase shift P is set.

[0048] The Figure 2Figure 8 shows an embodiment of a vehicle arrangement 1 in which the control unit 8 generates control commands that set a phase shift P of +15°. For example, a second transducer element 7 is controlled with a delay relative to a first transducer element 6 in order to achieve the phase shift P. The set phase shift P results in a rotation of the detection range E by a horizontal angle α. Similarly, in the Figure 3 An embodiment is illustrated in which a phase shift P of -15° is set by corresponding control commands from the control unit 8. The detection range E of the ultrasonic sensor array 4 is thus pivoted by an angle -a.

[0049] Depending on the direction of travel of vehicle 2, standard ultrasonic sensors may not adequately cover the sides of the vehicle because their detection range is static. This reduces the localization accuracy of objects. This becomes particularly significant when vehicle 2 is maneuvering in a curve, such as when reversing into a parking space. While reversing in a straight line typically results in multiple object detections and therefore very precise object detection, object localization is considerably reduced when cornering, and there is correspondingly less redundancy. Besides localization accuracy, object classification (typically two classes: relevant to braking and warning, or drive-over) is a crucial aspect for an ultrasonic system. Due to the lack of coverage in the edge area, or...In the side area, the object data set underlying the classification is significantly smaller than in the central area or in the area of ​​a symmetry axis S, which considerably limits the classification. One consequence of this is a late correct classification, which can be described as a late first detection time (in the case of two-class classification). This is particularly relevant for scenarios with objects entering a tunnel F laterally, such as pedestrians or cyclists.

[0050] In the vehicle arrangement 1 according to the invention, the control unit 8 can receive measurement data from a unit 10, which can be configured, for example, as a steering angle sensor or as planned trajectory data, in order to determine the direction of travel of the vehicle 2. Based on the determined direction of travel, control commands are generated by the control unit 8 to actuate the converter elements 6, 7 with a phase shift P. The phase shift P can be dynamically adjusted or varied by the control unit 8 depending on the determined direction of travel. Thus, intelligent tracking of the detection range E to a driving tube F (see figure) is possible. Figure 4 ) to increase localization accuracy and classification in object detection.

[0051] The Figure 4Figure 1 shows schematic top views of a rear area of ​​a vehicle 2 with an adapted phase angle P during straight-ahead driving (left) and cornering (right) according to an embodiment of the invention and illustrates the intelligent tracking of the detection area E to the driving tube F.

[0052] The control unit 8 receives data from the vehicle control system, for example from a unit 10 configured as a steering angle sensor, and uses this data to precisely control the calculated driving path. The same data could be used here, for example, to display the route in the infotainment system and determine the expected driving path based on the current wheel position. However, this data is now used to control each transducer element 6, 7 of the ultrasonic sensor arrays 4 in such a way that the truly important area, especially the driving path F behind the vehicle 2, is better covered by the detection ranges.

[0053] For example, the two middle ultrasonic sensor arrays 4 can be operated without different phase control, whereas the two outer ultrasonic sensor arrays 4 each shift their main field of view inwards or towards the axis of symmetry S by phase control. As a result, from a certain distance behind the vehicle 2 in the relevant area F, there is almost exclusively quadruple coverage, thus providing better localization capability and redundancy.

[0054] In the case of a curve, as on the right in the Figure 4 As shown, all 4 ultrasonic sensor arrays can be controlled differently, so that the travel path is ideally "illuminated".

[0055] If, in general operation, the general environment is also to be examined in addition to the relevant area or the driving hose F, it is possible to switch between operating modes for scanning the detection area E without control of the phase shift P and with control of the phase shift P.

[0056] The phase shift P can be set differently by the control unit 8, for example, for a centrally arranged first ultrasonic sensor array 4 compared to a phase shift P of an ultrasonic sensor array 4' arranged laterally on the vehicle 2. For the sake of clarity, the control unit 8 is only shown in the Figures 1 to 3 depicted.

[0057] In the Figure 5Figure 1 shows a schematic top view of the rear area of ​​a vehicle 2 with detection areas E swiveled away from an axis of symmetry S of the vehicle 2 according to an embodiment of the invention. Several ultrasonic sensor arrays 4 arranged on the vehicle 2 can be controlled by the control commands of the control unit 8 in such a way that a "squinting" of the several ultrasonic sensor arrays 4 is achieved, so that the detection areas E of the ultrasonic sensor arrays 4 are rotated or deflected towards the sides of the vehicle. This increases the resulting detection area E of all ultrasonic sensor arrays 4.

[0058] Alternatively, a concentration or focus of the detection areas E towards the axis of symmetry S of the vehicle 2 is achieved. This reduces the resulting detection area E of all ultrasonic sensor arrays 4.

[0059] Preferably, the axis of symmetry S of the vehicle 2 is an axis directed in the longitudinal direction x, which passes through a vehicle center, in particular between a driver's seat and a passenger's seat.

[0060] The Figure 6 Figure 1 shows a schematic flowchart illustrating a method 20 according to the invention in one embodiment. The method 20 serves to adjust a detection range E of at least one ultrasonic sensor array 4 of a vehicle 2 by a control unit 8.

[0061] In step 22, measurement data is received. Based on the received measurement data, a direction of travel is determined.

[0062] In a further step 24, control signals are generated to control at least two transducer elements 6, 7 of the at least one ultrasonic sensor array 4.

[0063] The control signals set a phase shift P between the ultrasonic waves sent by the transducer elements 6, 7 and / or a phase shift P between the ultrasonic waves received by the transducer elements 6, 7, which is adapted to the direction of travel of the vehicle 2.

Claims

1. Method (20) for adjusting a detection area (E) of at least one ultrasonic sensor array (4) of a vehicle (2) by means of a control unit (8), wherein - measurement data are received and a direction of travel is determined (22), - control signals for controlling at least two transducer elements (6, 7) of the at least one ultrasonic sensor array (4) are generated (24), wherein a phase shift (P) between the ultrasonic waves transmitted by the transducer elements (6, 7) and / or a phase shift (P) between the ultrasonic waves received by the transducer elements (6, 7) is / are set (26) by way of the control signals, said phase shift being adapted to the direction of travel of the vehicle (2), characterized in that, when the vehicle (2) is travelling in a straight line, a detection area (E) of at least one first ultrasonic sensor array (4) is concentrated by a positive phase shift (P) and a detection area (E) of at least one second ultrasonic sensor array (4') is concentrated by a negative phase shift (P) with respect to an axis of symmetry (S) of the vehicle (2) or directed away from the axis of symmetry (S) of the vehicle (2), wherein the axis of symmetry of the vehicle is an axis which is directed in the direction of travel and runs along the longitudinal direction of the vehicle through the centre of the vehicle, in particular between a driver's seat and a front passenger's seat.

2. Method according to Claim 1, wherein the measurement data for determining the direction of travel are received from a unit (10) configured as a parking assistance system, a steering angle sensor, a GNSS sensor, a trajectory planning system and / or a navigation system.

3. Method according to Claim 2, wherein a driving path (F) of the vehicle (2) is overlapped by the detection area (E) of at least one ultrasonic sensor array (4) in the direction of travel of the vehicle (2) or a driving path (F) of the vehicle (2) is overlapped by the detection area (E) of at least one ultrasonic sensor array (4) counter to the direction of travel of the vehicle (2).

4. Method according to one of Claims 1 to 3, wherein the respective phase shift (P) between the generated ultrasonic waves of at least two transducer elements (6, 7) of the respective ultrasonic sensor array which are arranged so as to be offset to each other along a transverse direction (y) and / or along a vertical direction (z) is adjusted by way of the generated control signals, wherein the transducer elements (6, 7) are at a distance from each other in the transverse direction (y) and / or in the vertical direction (z) of at least half a wavelength (lambda) of the generated ultrasonic waves.

5. Method according to one of Claims 1 to 4, wherein the phase shift (P) of transducer elements (6, 7) of the respective ultrasonic sensor array of the at least two ultrasonic sensor arrays (4) is adjusted by way of the generated control signals such that the detection areas (E) of the at least two ultrasonic sensor arrays (4) overlap in the area of the driving path (F) of the vehicle (2).