WO2025082757A1 - Method for adjusting a vertical principal axis of sound emission and sound reception - Google Patents

Abstract

The invention relates to a method (100) for dynamically adjusting an elevation principal axis of sound emission and/or sound reception, wherein an inclination angle of a sensor is automatically adjusted on the basis of one or more measured ground reflections, comprising at least method steps in a manufacturing device (120) and in vehicle operation (122).

Description

Description

title

Technical area

The invention relates to a method for dynamically adjusting a principal elevation axis. Dynamic adjustment involves adjusting the inclination angle of a sensor based on one or more measured ground reflections and includes method steps in a manufacturing facility and in a vehicle operation.

State of the art

State-of-the-art ultrasonic array sensors enable the replacement of mechanical sound field shaping with digital beam steering.

This requires the sensor's inclination angle to be adjusted as precisely as possible, since the directional sound radiation (and also the directional reception) determines the sensor's sensitivity. This means that the higher the echo amplitudes in the ground, the higher the threshold value and the lower the sensor's sensitivity.

Due to their low manufacturing tolerances, mechanical funnels in classic ultrasonic array sensors allow the angle of inclination to be adjusted with a tolerance of < 1 °, which ensures a defined and as constant as possible sensitivity of the sensors for a given substrate.

When replacing the mechanical funnels with a digital beamforming system, the digital beamforming system must be adjusted to the same tolerance to meet the state of the art. However, this is technically very complex and therefore not feasible with reasonable effort for the following reasons: a) the set phase and amplitude differences, transmitted and received, must be able to be set with a high resolution for each sensor in the production plant; b) the set phase and amplitude differences, transmitted and received, must be able to be set with a high resolution for each sensor in the production plant.

Another shortcoming of traditional ultrasonic array-based sensor systems is the dependence of sensor sensitivity on the surface. Highly reflective surfaces, such as gravel or crushed stone, result in reduced sensitivity due to the higher adaptive threshold, thus reducing the field of view. For such surfaces, it is effective to dynamically increase the tilt angle to minimize ground reflections. The opposite is true for low-reflection surfaces.

If the sensors are misaligned due to installation errors or accidents, tilt angles can occur that are well outside the permissible tolerance range. With conventional state-of-the-art USS sensors, these cannot be compensated for, so influences on sensor sensitivity and field of view remain uncompensated.

DE 10 2021 211 597 A1 relates to a method for controlling at least one ultrasonic sensor array for emitting ultrasonic echoes into a detection zone. The ultrasonic sensor array comprises at least two transducer elements spatially separated from one another in the vertical and/or horizontal direction, which are controlled in a phase-shifted manner by a control unit electrically connected to the transducer elements in order to tilt a main axis of the emitted sound echoes relative to a surface normal of the ultrasonic sensor array. Furthermore, a method for controlling at least one ultrasonic sensor array for receiving reflected sound echoes from a detection zone, a control device, a data processing program, and a machine-readable storage medium are disclosed. Disclosure of the invention

According to the invention, a method for dynamically adjusting a main elevation axis of a sound emission and/or a sound reception is proposed, wherein an automatic adjustment of an inclination angle of a sensor is carried out on the basis of one or more measured ground reflections, comprising at least method steps in a production facility and in a vehicle operation.

The method proposed by the invention for dynamically adjusting the elevation principal axis of a sound emission and/or reception allows highly accurate methods for measuring, identifying, and tracking phase and amplitude drift caused by aging and temperature to be avoided. Furthermore, dynamic adjustment of the inclination angle can ensure a nearly constant sensor sensitivity and thus a constant detection range, as well as compensate for potential alignment errors.

In an advantageous development of the method proposed according to the invention, comprising at least method steps in a production facility and in a vehicle operation, the method (100) has at least the following steps: i. Compensation of component-related phase and amplitude differences, ii. Storing one or more compensation values in a sensor, wherein the one or more compensation values comprise the one or more initial values for the vehicle operation, iii. Detecting one or more ground echo amplitudes in a range of a clutter maximum per sensor for a measuring cycle and calculating a ground reflection value per sensor, iv. Correcting one or more ground echo amplitudes, v. Statistically detecting a ground reflection value, vi. Determining a difference between a detected ground reflection value and a ground reflection target value, vii. Determining a sensor-specific inclination angle correction, viii. Storing an inclination angle correction at a specific

Temperature and checking a correction and ix. Control and verification of an inclination angle.

Using the method proposed by the invention in step iii, a ground reflection value (also called ground reflection coefficient or ground reflection factor) can be calculated, for example, from the sum of all amplitude heights of reflected sound waves divided by a number of measured amplitudes (i.e., an average of the amplitude heights). Alternatively, an evaluation of the ground amplitudes using methods such as histograms, averaging, or integral calculation of the ground echo amplitudes can be used to calculate a ground reflection value.

The method proposed by the invention in step iv corrects the ground echo amplitudes by extracting the echoes that do not originate from the drivable subsurface from a detection or by correcting the ground reflection value determined in step ii. The echoes can be detected, for example, based on measured elevation angles to the echoes and, if necessary, other features such as amplitude and correlation value.

Elevation principal axis refers to a vertical axis or direction in which the sensor can be moved or aligned up or down.

The method proposed by the invention in step v. performs a statistical recording of the ground reflection values. The ground reflection values determined in step iv. are recorded over several measurement cycles. This occurs immediately before a sensor-specific tilt angle correction about the principal elevation axis. The duration of a measurement cycle can, for example, be approximately 160 milliseconds (ms).

In step vi, the method according to the invention determines a difference between the sensor-specific ground reflection value determined in steps iii to v and the target ground reflection value. The target ground reflection value is determined, for example, in advance during a development phase. The determination can be made, for example, through an analysis of multiple substrates, measured or simulated. This target ground reflection value is referred to as the target sensitivity of the sensor. A sensor-specific tilt angle correction of an ultrasonic sensor is a method in which measurements and associated data are used to correct the digitally adjustable tilt angle so that the sensor's sensitivity remains as constant as possible and disturbances, for example due to increased ground clutter or misalignment, do not influence the measurement results. An inclination angle is an angle by which a sensor is inclined with respect to the elevation axis or another reference plane. The setting of the sensor-specific tilt angle correction by the method proposed according to the invention in step vii. is carried out on the basis of the difference determined in step vi between the determined sensor-specific ground reflection value and the ground reflection target value specified for the sensor in question.

Furthermore, it is advisable to limit the tilt angle correction, for example, since a large tilt angle correction of, for example, more than 15% leads to a significant loss of echo amplitudes for objects with reflection points at or above sensor height. To avoid physically implausible corrections, a limit can also be set for positive and negative corrections.

Within the scope of step viii of the method according to the invention, a correction is performed in a control loop after each cycle. Preferably, the inclination angle correction is performed for both sound emission and sound reception; alternatively, the inclination angle correction can be performed either for sound emission or for sound reception.

The tilt angle correction at a specific temperature is stored by storing sensor-specific correction values. A sensor-specific correction value comprises a value of the determined tilt angle by which a sensor-specific tilt angle correction is performed. The stored sensor-specific correction value is then loaded as the new initial value for step iii when the system is restarted.

Sound radiation and reception properties can be affected by temperature and aging. This means that the initial value from step ii., which is stored at the end of the tape, can, under certain circumstances, lead to a significant deterioration in detection. until the correction from step vii. takes effect. Therefore, it seems expedient to replace this initial value over the operating time, if possible. To this end, the sensor-specific correction values from step viii. are preferably stored temperature-dependently during operation and loaded as the new initial value for step iii. when the system is restarted.

The influences related to age and temperature can be interpreted as continuous drift. Time- or temperature-related fluctuations in the correction values are therefore physically implausible. This makes it possible to check the plausibility of the tilt angle corrections determined in step vii. and to filter out outliers in the correction values. State-of-the-art methods, such as Kalman filters, can be used for this purpose. Extreme outliers, for example, can be detected by repeatedly occurring extreme values in the tilt angle corrections.

By means of the method proposed according to the invention, a control and verification of an angle of inclination takes place in step viii., wherein after running through steps iii. to viii., a correction of the angle of inclination is verified in the form of a control loop by running through steps iii. to viii. again and is readjusted in the event of a deviation.

In an advantageous development of the method proposed according to the invention, a compensation of component-related phase and amplitude differences is carried out in step i. with a target tolerance in the range of 4° to 10°, preferably 5° to 8°, particularly preferably 6°.

The method according to the invention for compensating component-related phase and amplitude differences is understood to be a method in which deviations or differences in the phase or amplitude of a signal are corrected or compensated in order to achieve or maintain a desired signal quality. For example, a target tolerance for phase and amplitude differences in a sensor can be defined, ensuring that the compensated phase and amplitude differences remain within this tolerance limits. This can be achieved, for example, by calibrating the sensor.

In an advantageous development of the method proposed according to the invention, a measurement of the phase and amplitude differences of an array element is carried out before final assembly and an adjustment of a main elevation axis is checked.

In an advantageous development of the method proposed according to the invention, the clutter maximum is given by an installation height of the sensor.

For typical installation heights of the ultrasonic sensors of, for example, 30 to 70 cm, a clutter maximum occurs in the range of 0.4 m to 2.5 m; in this range, the ground echo amplitudes are measured for each sensor.

Using the method proposed by the invention in step iii, a ground reflection value (also called ground reflection coefficient or ground reflection factor) can be calculated, for example, from the sum of all amplitude heights of reflected sound waves divided by a number of measured amplitudes (i.e., an average of the amplitude heights). The ground reflection coefficient is preferably determined from the amplitudes at the sensor's installation height in the range between 0.5 m and 2.5 m.

In the method proposed by the invention, a correction of the ground amplitudes is performed in step iv., so that echoes originating from impassable ground are disregarded during detection, or the ground reflection values determined in step ii. are corrected. These echoes are detected based on the measured elevation angles to the echoes and, if necessary, based on other features such as amplitude and correlation value. This step iv. is preferably performed in conjunction with step iii.

In an advantageous development of the method proposed according to the invention, the detection and correction of a ground echo amplitude takes place in one method step. In a further advantageous embodiment of the method proposed according to the invention, one or more ground echo amplitudes are recorded over several, preferably at least 30, measuring cycles.

In the method according to the invention for detecting one or more ground echo amplitudes, it is proposed to carry out the detection over at least 30 measurement cycles. This has the advantage that the ground reflection values determined in step iv. vary from measurement cycle to measurement cycle due to the statistical nature of the ground reflections. It is therefore proposed to carry out the detection over 30 measurement cycles before adjusting the inclination angle of a main axis.

Alternatively, for example, in the case of large deviations of the ground reflection values from the specified tolerances, compensation can be carried out by checking the plausibility of the ground reflection values with one or more neighboring sensors using statistics.

In a further advantageous manner of the method proposed according to the invention, a table of an adjustable phase difference via a ground reflection increase is stored in an electronic control unit or a sensor.

In a further advantageous development of the method proposed according to the invention, a sensor-specific inclination angle correction is determined, wherein the inclination angle is adjusted.

In a further advantageous embodiment of the method proposed according to the invention, an initial value is read out from the determination of a sensor-specific inclination angle correction when a system for determining one or more ground echo amplitudes is restarted.

In a further advantageous development of the method according to the invention, a number of measuring cycles can be varied.

Alternatively, it is possible to detect larger deviations by checking the plausibility of the ground reflection values with the neighboring sensors with lower statistical accuracy and to start earlier with steps vi. to vii. compensate. Lower statistical accuracy refers to statistical recording of measured values, such as ground reflection values, over fewer than 30 measurement cycles, for example, three to five measurement cycles.

In a further advantageous development of the method according to the invention, steps i. to ii. are carried out in a production facility per sensor and steps iii. to xii. are carried out in vehicle operation per sensor.

Advantages of the invention

The inventive method for dynamically adjusting the elevation principal axis of a sound emission allows for advantageous adaptation of the sensor to changing environments and conditions. For example, by dynamically adjusting the inclination angle of a vehicle-mounted sensor, inclination information can be precisely recorded in real time, regardless of the ground conditions.

Furthermore, a method according to the invention can provide consistent sensor sensitivity while dynamically adapting the sensor. This, for example, maintains the accuracy of measured values.

Furthermore, a method according to the invention can reduce false alarms, for example when parking a vehicle. Through the dynamic adjustment of the inclination angle, a sensor can, for example, distinguish real inclination changes from temporary disturbances or vibrations.

Furthermore, a method according to the invention can achieve a constant field of view of the sensor (FOS) as well as a compensation of potential misalignment errors during dynamic sensor adjustment.

Furthermore, the method according to the invention eliminates the need for complex and cost-intensive high-precision calibration of 1-2° target tolerance in the factory. Furthermore, temperature and aging effects can be compensated by the method according to the invention.

Short description of the drawings

Embodiments of the invention are explained in more detail with reference to the drawings and the following description.

They show:

Figure 1 is a schematic representation of a method for dynamically adjusting a main elevation axis of a sound radiation,

Figure 2 is a schematic representation of a detection of several ground echo amplitudes in the area of a clutter maximum and

Figure 3 shows a schematic representation of the determination of a sensor-specific tilt angle correction.

Embodiments of the invention

In the following description of the embodiments of the invention, identical or similar elements are designated by the same reference numerals, whereby a repeated description of these elements is omitted in individual cases. The figures only schematically illustrate the subject matter of the invention.

Figure 1 shows a method 100, wherein the method 100 is illustrated in the form of a flow chart. Two areas can be seen in the method 100, wherein a first area represents an area in a production facility 120 and a second area represents an area in a vehicle operation 122. Both the area in the production facility 120 and the area in a vehicle operation 122 are assigned method steps. Thus, the steps of compensating 102 for design-related phase and amplitude differences and storing 104 one or more compensation values within a Production facility 120. The steps of detecting 106 one or more ground echo amplitudes 206, calculating 106.1 a ground reflection value per sensor 304, correcting 108 one or more ground echo amplitudes 206, statistically detecting 110 a ground reflection value, determining 111 a difference between a detected ground reflection value 108 and a target ground reflection value, determining 112 a sensor-specific tilt angle correction 310, storing 114 a sensor-specific tilt angle correction 310, checking 114.1 a correction, setting 116 a tilt angle 312, and verifying 118 a tilt angle 312 are carried out within vehicle operation 122.

It can also be seen from Figure 1 that the steps of detecting 106 one or more ground echo amplitudes 206 and calculating 106.1 a ground reflection value per sensor 304 are within one step according to method 100. This also applies to the steps of storing 114 a sensor-specific inclination angle correction 310 and checking 114.1 an inclination angle correction 312.

Alternatively, for example, in the case of larger deviations, such as deviations greater than 6° to 10°, the ground reflection values can be recorded with lower statistics, for example only three to five measuring cycles instead of 30 measuring cycles, by checking the plausibility of the ground reflection values with the neighboring sensors 304, and compensation can be carried out earlier with the steps of statistical recording 110 to verification 118.

Alternatively, a correction 108 of one or more ground echo amplitudes 206 can already be summarized in the steps of detecting 106 one or more ground echo amplitudes 206 and calculating 106.1 a ground reflection value per sensor 304.

For example, prior art methods 100, such as histogram, mean, or integral calculation of the ground echo amplitudes 206, can be used to detect 106 the ground echo amplitudes 206. From this, a characteristic ground reflection value can be determined for each sensor 304 and each measurement cycle. The illustration according to Figure 2 uses a diagram 200 to show a procedure for detecting 106 ground echo amplitudes 206. In the diagram, seven ground echo amplitudes 206 are shown in a distance-amplitude diagram, the distance 204 being given in meters and the intensity of the amplitudes 202 being plotted on the Y-axis, a rectangular bar being shown within the diagram as a clutter maximum 212, in which a clutter maximum 212 represents a minimum distance 208 from the clutter maximum 212 and a maximum distance 210 from the clutter maximum 212.

For example, a ground reflection value can be calculated from the detected 106 ground echo amplitudes 206 by averaging the ground echo amplitudes 206 (as shown in the following formula 1).

formula 1

In Figure 3, a procedure 300, a determination 112 of the sensor-specific inclination angle correction 310 is carried out, wherein an upper diagram shows a time before a sensor-specific correction 300.1 and a lower diagram after a sensor-specific correction 300.2.

The two diagrams in Figure 3 each show a vehicle 302 and a sensor 304 attached to a vehicle 302. Each diagram shows a detection range 306 of the respective sensor 304 as well as the principal elevation axis 308. In the upper diagram, before a sensor-specific correction 300.1, it can be seen that the principal elevation axis 308 of the sensor 304 runs horizontally. In the lower diagram, after a sensor-specific correction 300.2, it can be observed that the principal elevation axis 308 of the sensor 304 is inclined upwards by an inclination angle 312 due to a sensor-specific inclination angle correction 310.

The adjustment of the inclination angle 312 is carried out, for example, via a determined difference 111. Furthermore, the adjustment of the inclination angle 312 can be carried out, for example, via the phase position between the vertically arranged sensor elements. The invention is not limited to the embodiments described here and the aspects highlighted therein. Rather, numerous modifications are possible within the scope of the claims, which are within the scope of expert practice.

Claims

Claims 1 . Method (100) for dynamically adjusting a main elevation axis (308) of a sound emission and/or a sound reception, wherein an automatic adjustment of an inclination angle (312) of a sensor (304) is carried out on the basis of one or more measured ground reflections, comprising at least method steps in a production facility (120) and in a vehicle operation (122). 2. The method (100) according to claim 1, comprising at least method steps in a manufacturing facility (120) and in a vehicle operation (122), wherein the method (100) has at least the following steps: i. compensation (102) of component-related phase and amplitude differences, ii. storage (104) of one or more compensation values in a sensor (304), wherein the one or more compensation values comprise the one or more initial values for the vehicle operation (122), iii. detection (106) of one or more ground echo amplitudes (206) in a region of a clutter maximum (212) per sensor (304) for a measuring cycle and calculation (106.1) of a ground reflection value per sensor (304), iv. correction (108) of one or more ground echo amplitudes (206), v. Statistical recording (110) of a ground reflection value, vi. Determination (111) of a difference between a recorded (106) ground reflection value and a ground reflection target value, vii. Determination (112) of a sensor-specific tilt angle correction (310), viii. Storage (114) of a sensor-specific tilt angle correction (310) at a specific temperature and checking (114.1) a correction, ix. Control (117) and verification (118) of an inclination angle (312). 3. Method (100) according to one of the preceding claims, wherein a compensation (102) of component-related phase and amplitude differences is carried out with a target tolerance in the range of 4° to 10°, preferably 5° to 8°, particularly preferably 6°. 4. The method (100) according to any one of the preceding claims, wherein, prior to final assembly, a measurement of the phase and amplitude differences of an array element is carried out and an adjustment of a principal elevation axis (308) is checked. Method (100) according to one of the preceding claims, wherein the clutter maximum (212) is given by an installation height of the sensor (304). 5. Method (100) according to one of the preceding claims, wherein the detection (106) and the correction (108) of a ground echo amplitude (206) takes place in one method step. 6. Method (100) according to one of the preceding claims, wherein the detection (106) of one or more ground echo amplitudes (206) takes place over several, preferably at least 30, measuring cycles. 7. The method (100) according to any one of the preceding claims, wherein a table of an adjustable phase difference via a ground reflection increase is stored in an electronic control unit or a sensor (304). 8. Method (100) according to one of the preceding claims, wherein the determination (112) of a sensor-specific inclination angle correction (310) is read out upon restart of a system for detecting (106) one or more ground echo amplitudes (206). 9. Method (100) according to one of the preceding claims, wherein a number of measuring cycles is variable. 10. The method (100) according to any one of the preceding claims, wherein steps i. to ii. are carried out in a manufacturing facility (120) per sensor (304) and steps iii. to xii. are carried out in vehicle operation (122) per sensor (304).