Method for measuring height in vehicle, control unit and vehicle

Abstract

The invention relates to a method for measuring the height in a vehicle (10) having a height adjustment mechanism, in which a sensor (19) for measuring the height is arranged on a chassis (11) of the vehicle (10) or is connected to the chassis (11) at a defined distance. The sensor (19) is arranged to be able to detect a distance (A, aA) from an axle (14) of the vehicle (10) and in particular also from the ground (23) below the vehicle (10). The sensor (19) transmits a signal in the direction of the axle (14) and in particular the ground (23), and receives a reflected signal and its strength (I). The sensor (19) also at least indirectly detects a propagation time between the transmitted signal and a reflected signal as a signal peak (P1 to P6). The propagation time represents the distance (A, aA) of the sensor (19) relative to the axle (14) and especially also relative to the ground (23) or can be converted into the distance (A, aA).

Description

Technical Field

[0001] The present invention relates to a method for measuring height in a vehicle having a height adjustment mechanism, wherein a sensor for measuring height is arranged on the chassis of the vehicle or connected to the chassis at a defined interval, the sensor is arranged to detect the distance relative to the axle of the vehicle and, in particular, the distance relative to the ground below the vehicle, and the sensor transmits a signal toward the axle, receives a reflected signal and at least indirectly detects its intensity and the propagation time between the transmitted signal and the reflected signal as a signal peak, wherein the propagation time represents or can be converted into the distance between the sensor and the axle and, in particular, the ground. Background Technology

[0002] The vehicles involved are particularly those with air suspension, especially commercial vehicles. Other types of suspension and vehicles may also be involved, provided they have a height adjustment mechanism.

[0003] In particular, the vehicle is equipped with a central control unit for the air suspension or height adjustment mechanism. This control unit can also be a component of the braking system.

[0004] Furthermore, the vehicle is specifically a trailer vehicle. However, it can also be a tractor-trailer.

[0005] In particular, the vehicle is equipped with two or more axles. It can also be a single-axle trailer.

[0006] A sensor device contains a transmitter and a receiver, or a combination of transmitters and receivers, which are coordinated with each other or interconnected in terms of circuitry.

[0007] Commercial vehicles and passenger vehicles can be equipped with height adjustment mechanisms. The height of the chassis above the axle can be set. In particular, the vehicle is equipped with air suspension, which allows for height adjustment.

[0008] To perform targeted height adjustments, the current height needs to be detected. In this regard, it is known to use sensors configured as transmitters and receivers, sending signals toward the axle, receiving reflected signals, and detecting their intensity and propagation time as signal peaks. Given the signal velocity, the propagation time is also a measure of the distance between the sensor and the axle. If propagation time is mentioned below and in connection with this invention, it specifically also implies distance.

[0009] The use of radar sensors to detect altitude is known according to EP 4 020 012 A1. In connection with this invention, the sensors used are, in particular, radar sensors.

[0010] Radar sensors used for measuring distance and motion around a vehicle have long been known, for example, see the Bosch Vehicle Technical Manual, 27th edition (2011), starting from page 1154, chapter “Sensor technology for driver assistance systems”, and subsequent editions.

[0011] Also known are radar sensors used for measuring vehicle interior spacing and motion, such as the AWRL6432 radar sensor from Texas Instruments and the A111 radar sensor from Acconeer AB.

[0012] The sensors should reliably detect the position of the axle relative to the chassis in order to determine the current distance between the axle and the chassis. In particular, the sensors should also detect the surface on which the vehicle moves, i.e., the ground.

[0013] Radar sensors and other types of sensors have a spatial beam angle for the emitted signal, approximately conical, etc. The sensors are specifically arranged on the chassis in such a way that they can reliably detect the axle and / or the ground. Furthermore, there may be components on the axle and extending from the chassis that are located within the radiation cone of the sensor signal and are detected together. Signals reflected from these components are detected by the sensor in the same way as signals from the axle and / or the ground.

[0014] When installing sensors, they need to be calibrated so that they can reliably distinguish between the axle and / or the ground and other components. Calibration should be automated as much as possible. Summary of the Invention

[0015] The method according to the invention has the features of claim 1. Accordingly, the method for measuring height is applicable to vehicles having a height adjustment mechanism, wherein a sensor for measuring height is arranged on the chassis of the vehicle or connected to the chassis at a defined interval, the sensor is arranged to detect the distance relative to the axle of the vehicle and, in particular, relative to the ground below the vehicle, and the sensor transmits a signal toward the axle, receives a reflected signal and at least indirectly detects its intensity and at least indirectly detects the propagation time between the transmitted signal and the reflected signal as a signal peak, wherein the propagation time represents or can be converted into a distance relative to the distance between the sensor and the axle and, in particular, relative to the ground. In particular, for calibration, the following steps are performed:

[0016] a) The vehicle can be adjusted to different heights via a height adjustment mechanism.

[0017] b) For each height controlled in step a), the propagation time and signal strength of the reflected signal are determined, thereby generating an original signal dataset consisting of the propagation time and signal strength of the signal peak for each controlled height.

[0018] c) Based on the propagation time and signal strength obtained in step b), identify the signal peak that always has the same propagation time regardless of the height driven out.

[0019] d) The signal peaks identified in step c) that always have the same propagation time together form a background dataset, which is stored for further use.

[0020] The method described above first yields a raw signal dataset for each controlled height, consisting of signal peaks including propagation time and signal strength. This can be achieved by gradually changing the height in various ways and methods, such as adjusting it by one millimeter, one centimeter, or other amounts, particularly by approximately 0.5 millimeters, especially starting from a minimum or maximum value. A raw signal dataset is then created for each set height.

[0021] It could also be a continuous adjustment of altitude, such as one centimeter per second (1 cm / s). The sensor can send its signal at defined time intervals and detect signal peaks, thereby generating raw signal datasets for different altitudes.

[0022] The original signal dataset is used to identify signal peaks that remain consistent despite varying height settings. This identification can be aided by mathematical methods. Methods for identifying patterns in the dataset are known across numerous application areas and will not be elaborated upon here. The identified signal peaks relate to components whose height relative to the chassis remains constant, thus interfering with height measurements. Examples include linkages or other types of attachments fixed to the chassis and located within the sensor's radiation cone. These signal peaks together constitute the background dataset, which can be stored and optionally used in the method.

[0023] According to an optional aspect of the invention, the signal peaks of the background dataset are subtracted from the signal peaks of all original signal datasets to generate a corrected signal dataset for each original signal dataset, which is then stored. The stored corrected signal datasets can optionally be used in further methods. In addition, the peak dataset may also include other selected signal peaks. Depending on the selection of signal peaks, the size of each stored signal dataset can be significantly reduced, which simplifies subsequent processing.

[0024] According to an alternative idea of ​​the invention, signal peaks involving the axle and, in particular, the ground (i.e., axle signal peaks and, in particular, ground signal peaks) are identified in each calibrated signal dataset. The calibrated signal dataset contains only signal peaks of components with variable height relative to the chassis (i.e., axle signal peaks), especially ground signal peaks, and perhaps other signal peaks. Typically, axle signal peaks are the strongest signal peaks with shorter propagation times, while ground signal peaks are relatively strong signal peaks with longer propagation times. Due to the shorter distance relative to the sensors and the size of the axle, axle signal peaks tend to have the highest intensity of all signal peaks. In a factory environment, ground signal peaks have the longest propagation time. Therefore, axle signal peaks and ground signal peaks can be determined relatively reliably by their signal strength and propagation time. The calibrated signal dataset (in which at least axle signal peaks and, in particular, ground signal peaks are identified) is referred to herein as a peak dataset.

[0025] According to an optional aspect of the invention, at least the axle signal peaks and, in particular, the ground signal peaks of the calibrated signal dataset are saved as a peak dataset. In this case, the peak dataset is a simplified calibrated signal dataset, wherein at least the axle signal peaks and, in particular, the ground signal peaks are identified. Additionally, other signal peaks that may exist may also be saved together in the peak dataset. In extreme cases, the signal peaks of the peak dataset are consistent with the signal peaks of the calibrated signal dataset.

[0026] Optionally, and according to the present invention, the method may include the following steps:

[0027] e) For at least one height of the vehicle, compare multiple or all signal strengths with each other to determine the highest signal strength.

[0028] f) If the highest signal strength can be obtained, it is defined as the portion of the axle signal peak value.

[0029] g) If the highest signal strength cannot be determined, a reflector should be installed on the axle to improve the reflection of the transmitted signal.

[0030] h) After installing the reflector, repeat steps a) through c).

[0031] The goal is to identify the peak value of the axle signal. If a signal peak is significantly more prominent than other signal peaks, it is likely an axle signal peak. For example, when two highest signal peaks have the same or only slightly different signal strengths, there is no significant difference. The degree of "slight" in this sense can be specified by parameters. If the axle signal peak cannot be identified in this way, the method is interrupted and a reflector is installed on the axle to improve reflection, thereby increasing the signal strength of the axle signal peak. After installing the reflector, steps e) to g) are repeated. If the axle signal peak can now be identified, the method continues according to claim 1. In cases where the highest signal strength cannot be identified, it can be displayed, for example, by showing a visible signal to the operator.

[0032] According to an alternative idea of ​​the invention, a signal strength is selected as the highest signal strength if it is at least a predetermined amount higher than each other compared signal strength. This predetermined amount is in particular an absolute quantity or a predetermined percentage relative to the lower or higher signal strength, such as 5% or 10%. The strength itself is specifically defined as the ratio of the received reflected signal to the transmitted signal and can be expressed as a percentage.

[0033] According to an alternative idea of ​​the invention, a signal strength that is higher than the axle signal peak by a predetermined amount in propagation time, and particularly higher than the adjacent signal strength by a predetermined amount, can be selected as the ground signal peak. The difference in propagation time between the ground signal peak and the axle signal peak is known within a relatively narrow limit, constrained by the known diameter of the wheels on the axle. A minimum and a maximum value can be given for the higher propagation time. Furthermore, it is expected that the ground, due to its large area, will provide a reflected signal with a relatively high signal strength. If components arranged on and extending below the axle also provide reflected signals, their signal strength may be lower. With the above additional conditions, the ground signal peak can be reliably determined.

[0034] According to an alternative idea of ​​the invention, the vertical spacing relative to the axle can be calculated and stored based on the axle signal peak value through linearization. If only the axle signal peak value is of interest, the calculation can be performed using propagation times representing different spacings during calibration. However, if the axle signal peak value and the ground signal peak value are compared, linearization of the axle signal peak value may be meaningful. This is due to the chassis geometry of the axle suspension. The axle is, for example, held on a longitudinal control arm and supported by air springs. In height adjustment mode, the axle moves along a partially circular trajectory, that is, the motion has vertical and horizontal components, both of which are variable.

[0035] Furthermore, sensors are often not vertically mounted above the axle. Therefore, the propagation time of the axle signal peak cannot be directly converted into the vertical distance between the axle horizontal plane and the sensor horizontal plane. Instead, the sensor position and the partial circular motion of the axle must be considered. This is referred to here as linearization. The result of linearization is the vertical axle spacing, that is, the vertical distance between the axle plane and the sensor plane. Linearization can be easily achieved given an understanding of the chassis geometry and the sensor's arrangement relative to the axle, and does not require further explanation here.

[0036] The previously mentioned peak dataset, in addition to containing the propagation time / spacing of the vehicle-axle signal peaks, can also include the vertical spacing relative to the vehicle-axle, obtained through linearization, or it can replace the original data. Alternatively, a linearized peak dataset can be created and saved based on the existing peak dataset through linearization. Here, the linearized peak dataset can replace the existing peak dataset or be saved in parallel. Whether linearization is meaningful can be determined by considering the deviation between the peak dataset and the linearized peak dataset that occurs in specific vehicle practices.

[0037] According to an alternative idea of ​​the invention, for calibration, two or more different heights are driven out, in particular continuously or intermittently. The background dataset can be obtained from the two different heights. In particular, more different heights are driven out.

[0038] According to an alternative aspect of the invention, for calibration purposes, at least the minimum and maximum heights of the vehicle are controlled. At least for the minimum and maximum heights of the vehicle, the theoretical distances between the ground and the sensors, and between the axles and the sensors, can be determined based on the chassis geometry, thereby enabling additional checks on the reliability of the data obtained.

[0039] According to an alternative concept of the invention, for calibration, the vehicle can be driven from its minimum height to its maximum height, or vice versa. This can be achieved by first, for example, deflating the air springs, then gradually or continuously inflating them until the maximum height is reached. The range from the minimum height to the maximum height defines the measurement range within which calibration can be performed.

[0040] According to an alternative concept of the invention, a radar sensor can be used as the sensor. Radar sensors are less sensitive to contamination compared to optical transmitters and receivers. In particular, the radar sensor operates according to the FMCW (Frequency Modulation Continuous Wave) or PCR (Pulse Coherent Radar) method. The radar sensor can operate, in particular, in the frequency range of 50 GHz to 100 GHz, especially at approximately 60 GHz or approximately 77 GHz. The beam angle can be, in particular, from 10° to 30°. Alternatively, other sensor technologies, such as ultrasonic sensors or lidar sensors, especially sensors with acute beam angles, can be used.

[0041] According to an optional aspect of the present invention, given existing peak datasets and existing background datasets, the following steps can be set after vehicle startup:

[0042] - Create at least one current raw signal dataset.

[0043] - The current peak dataset to which it belongs is calculated by subtracting the existing background dataset from the current original signal dataset.

[0044] - Identify the current axle signal peak within the current peak dataset by comparing the current peak dataset with existing peak datasets or by selecting the highest current signal peak.

[0045] The operation of the ignition switch or the start button is specifically defined as the starting of the vehicle. Peak and background datasets must already exist. The peak dataset can also be a linearized peak dataset. After vehicle startup, the sensors automatically activate and generate a new raw signal dataset, referred to as the current raw signal dataset, and are updated cyclically. The goal is to determine the current axle signal peak value, and thus, the current vehicle height. To this end, the existing background dataset is subtracted from the current raw signal dataset to calculate the current calibrated signal dataset and the current peak dataset. The current axle signal peak value is obtained by comparing the current peak dataset with the existing peak dataset or by selecting the highest current signal peak value. The current vehicle height can be inferred from the propagation time of the current axle signal peak value. During vehicle operation, these steps are automatically cyclical or repeated as needed. These steps are specifically executed by program control.

[0046] According to an alternative aspect of the invention, the current vertical distance relative to the axle can be calculated via linearization based on the propagation time of the current axle signal peak. Depending on the chassis geometry and sensor arrangement, the vertical distance, and therefore also the current vehicle height, may deviate from the distance between the sensor and the axle.

[0047] According to an alternative idea of ​​the present invention, the reliability of the identified current axle signal peak can be checked by the following measures:

[0048] - Check: Does the current peak dataset have ground signal peaks that match the identified current axle signal peaks in terms of their propagation time and / or signal strength?

[0049] - Check: Does the current peak dataset have other signal peaks that match the identified current axle signal peaks in terms of their propagation time and / or signal strength?

[0050] The ground signal peak must have a certain distance from the vehicle axle signal peak, where the distance can only fluctuate slightly. Furthermore, the current ground signal peak must belong to the same existing peak dataset as the current vehicle axle signal peak. The same applies to other current signal peaks in the current peak dataset. If confidence cannot be confirmed during the check, an error message can be output.

[0051] According to an alternative idea of ​​the invention, depending on the result of the confidence check, another current signal peak can be selected as the current axle signal peak, or in particular for another height of the vehicle, and the previously given steps can be repeated.

[0052] The subject of this invention, according to claim 18, is also a sensor for measuring height in a vehicle, having software for performing the method according to the invention. The sensor, as an integrated component, may be equipped with a processor, memory, and a user-programmable area for processing the acquired data; see also the aforementioned radar sensor for measuring distance and motion within a vehicle.

[0053] The subject of this invention, according to claim 19, is a control unit with software for performing the method according to the invention. The control unit acquires data from the sensors and controls the sensors. Furthermore, the control unit may, for example, adjust the vehicle height adjustment mechanism by driving an air spring, or transmit data to another control unit for height adjustment and / or control of the air spring.

[0054] The subject of this invention is, according to claim 20, a vehicle having a height adjustment mechanism, a chassis, at least one axle, a sensor according to claim 18 or a sensor for measuring height, or a control unit according to claim 19. Attached Figure Description

[0055] Other optional features of the invention are obtained from the remaining description and claims. Advantageous embodiments of the invention are further illustrated below with reference to the accompanying drawings. In the drawings:

[0056] Figure 1 The bottom view of a vehicle with three axles is shown.

[0057] Figure 2 The vertical cross-sectional diagram shows the... Figure 1 The vehicle is shown to have an axle equipped with sensors for measuring height.

[0058] Figure 3 The sensor and axle are shown to illustrate how height is measured by detecting the propagation time of the reflected signal.

[0059] Figure 4 The peak value of the reflected signal, which has intensity with respect to the spacing within a first measurement range, is shown.

[0060] Figure 5 The signal peak value is shown as the intensity of the reflected signal with respect to the spacing within the second measurement range.

[0061] Figure 6 The signal peak value is shown as the intensity of the reflected signal with respect to the distance within the third measurement range.

[0062] Figure 7 The fixed points on the chassis are shown, according to Figures 4 to 6 The measured signal peak value is used as the so-called background map.

[0063] Figure 8 Showing according to Figure 4 Signal peak minus according to Figure 7 Background image,

[0064] Figure 9 Showing according to Figure 5 Signal peak minus according to Figure 7 Background image,

[0065] Figure 10 The arrangement of the sensor relative to the axle and the movement of the axle along a partial circular trajectory are shown to illustrate the difference between the distance between the sensor and the axle and the distance perpendicular to the axle. Detailed Implementation

[0066] First refer to Figure 1 and Figure 2 The vehicle 10, comprising a chassis 11, a body 12, and three axles 13, 14, and 15, is height-adjustable via air springs 16 and 17. Specifically, the vertical distance VA between the axles 13, 14, and 15 and the chassis 11 above them can be set by adjusting the air springs 16 and 17. Such vehicles have been developed and used for various purposes over decades, particularly as commercial vehicles, including those used for transporting goods and / or personnel. Driven vehicles are especially common. However, trailer vehicles are also possible.

[0067] Modern vehicles of the aforementioned type have an electronic control unit 18 for air suspension. The control unit 18 may be connected to or be part of the brake control unit.

[0068] As input parameters for controlling the height adjustment mechanism, the control unit 18 requires information about the current vertical spacing aVA, and additionally requires information about the current spacing aA (only... Figure 3 Information is provided by a sensor 19 located on the lower side 20 of the chassis 11. The sensor 19 is a radar sensor, connected to the control unit 18 in a manner not further shown, and is a component known per se. If the sensor 19 protrudes downwards from the chassis 11, the vertical spacing VA, aVA, is specifically referenced to the sensor 19, as shown... Figure 2 As shown.

[0069] Different sensor types can be used as radar sensors, some of which are already available and others are still under development. In particular, a frequency range of approximately 60 GHz can be used.

[0070] In particular, a frequency-modulated continuous wave (FMCW) radar sensor is used here as sensor 19. This type of radar sensor is used in the automotive field for spacing detection and interior space monitoring. For the method of the present invention used to measure height, for example, the Texas Instruments AWRL6432 radar sensor can be used.

[0071] Alternatively, radar sensors that operate on the principle of pulse radar, especially pulse coherent radar sensors, can be used. An example of such a radar sensor is the Acconeer A111 Pulse Coherent Radar (PCR).

[0072] Sensor 19 detects objects within a generally conical, downward-pointing region (its radial cone), referred to herein as signal cone 21, and has a cone angle, particularly between 10° and 30°. It primarily detects the axle tube 22 of the axle 14 located below sensor 19. Simultaneously, signal cone 21 also detects the drivable surface beneath the axle 14, referred to herein as ground 23.

[0073] The same sensor 19 is installed in vehicles with different configurations. In particular, the vertical distance VA between the lower side 20 and the axle tube 22 can vary, regardless of the height adjustment mechanism that must be set regardless. Therefore, calibration is required when installing the sensor 19 and when it is first used. The latter should be performed automatically as much as possible. This would be relatively simple if the sensor 19 could only detect the axle 14 and the ground 23. In practice, there may be additional components or attachments under the chassis 11 and in the area of ​​the axles 13 to 15, which are also located in the area of ​​the signal cone 21 and are detected along with it. Figure 1and Figure 2 The diagram illustrates, for example, the link 24 below the sensor 19 and the attachment 25 on the axle 14. The link 24 and the attachment 25 are visible within the region of the signal cone 21.

[0074] The following combination Figure 3 The distance measurement of sensor 19 is described. For simplicity, only sensor 19, axle tube 22 of axle 14 and ground 23 are shown. A reflector (R) facing sensor (19) can be arranged on axle tube (22).

[0075] The radar signal is emitted by sensor 19 at time t0 as a signal cone 21. At time t8, the radar signal reaches axle tube 22, and at time t14, it reaches ground 23. Signals reflected from axle tube 22 and ground 23 (not shown) arrive at sensor 19 at times t16 and t28 and are detected there. Time points t8, t14, t16, and t28 represent only abstract time units relative to t0. It should be noted that, in the case of signals being emitted from sensor 19 together, the signal reflected from ground 23 arrives at sensor 19 significantly later than the signal reflected from axle tube 22. In this case, each time point t16 and t28 is a propagation time relative to time point t0, and is also a measure of the sensor-axle distance (t16-t0) and the sensor-ground distance (t28-t0). A propagation time of 1 ns corresponds to a signal path of approximately 30 cm and thus a distance of approximately 15 cm. For simplicity, only the distance is mentioned below, not the propagation time.

[0076] The reflected signals are not uniform, but vary in intensity. The intensity I depends at least on the nature of the object being detected and the distance A. Therefore, each reflected signal has a single intensity I in addition to a single value for the distance A. The intensity I and the distance A can be summarized as the term signal peak, which is its characteristic data, provided by sensor 19 for calculation and further processing in the vehicle or processed within sensor 19.

[0077] The reflected signal mentioned above is the signal received by sensor 19, generated by the reflection of the transmitted signal. Depending on the technology used, sensor 19 transmits individual signals and then pauses, allowing the reflected signal to be safely received during the pause. Alternatively, sensor 19 transmits a continuous signal that is periodically modulated. The reflected signal is then also modulated, but received at different times.

[0078] Figure 4 The graph shows the intensity I of the signal peaks P1 to P6 of a single transmitted signal with respect to spacing A. It can also be the signal peaks of multiple transmitted signals, where the average of the signal peaks has been determined. The signal peaks P1 to P6 involve the following components:

[0079] P1: The signal peak value of a component (e.g., link 24) that is positioned unchanged on the chassis 11.

[0080] P2: The signal peak value of axle 14 (i.e., axle tube 22).

[0081] P3: The signal peak value of the component (e.g., attachment 25) that is connected to the axle 13 in a fixed position.

[0082] P4: The signal peak value of another component (not shown in the figure) that is connected to the chassis 11 in the same position.

[0083] P5: Signal peak value at ground level 23.

[0084] P6: Signal peak value of depressions (e.g., pits not shown) in ground 23.

[0085] like Figure 4 and Figure 5 As shown, each signal peak P1 to P6 is the maximum value of a series of adjacent single peaks e. Each signal transmitted by sensor 19 generates multiple reflected signals, the specific number depending on the shape and structure of the surface detected by the radar beam. For simplicity, in Figure 4 , Figure 5 For each signal peak, three single peaks are plotted. Figures 6-9 The single peaks are not shown in the figure. The number and distribution of single peaks, as well as their spacing, may be completely different from those shown in the figure. Importantly, the maximum value of the single peak e is shown. The maximum value forms the signal peaks P1 to P6 to which it belongs.

[0086] The following combination Figures 4 to 10 Explain the possible calibrations for sensor 19:

[0087] After sensor 19 is installed on chassis 11, a series of measurements are performed. The results are evaluated. The evaluation is saved and used for measurements to be performed during vehicle 10 operation or for general use.

[0088] For the series of measurements described above, the height adjustment mechanism of vehicle 10 undergoes a so-called calibration drive. That is, the air springs 16 and 17 are gradually or continuously actuated, causing the height adjustment mechanism to travel its entire range from minimum to maximum, and vice versa. Depending on the desired resolution at different heights, more or fewer measurements are performed using sensor 19 during the calibration drive, and the signal peaks are saved as the raw signal dataset.

[0089] Figures 4 to 6 The example shows the signal peak values ​​of three different measurements. Figures 4 to 6 Each of these corresponds to a portion of the original signal dataset at a certain height. The original signal dataset contains the intensity I and spacing A for each signal peak.

[0090] Figure 4 The signal peak value of the first measurement at the minimum height of chassis 11 above axle 14 is shown, corresponding to the distance A from axle tube 22 to sensor 19, which is, for example, 20 cm. This can be seen at the signal peak value P2 at position A = 20 cm. Additionally, other signal peak values ​​P1, P3, P4, P5, and P6 are recorded at other positions a. P5, as the signal peak value of ground 23, is located at position A = 60 cm, that is, further away from sensor 19 by 40 cm compared to the signal peak value P2 of axle 14. The signal peak value P6, drawn with a dashed line, is further away by 20 cm and will not appear during calibration driving in a controlled workshop environment with a flat surface. In subsequent driving operations, signal peak value P6 can, for example, indicate potholes.

[0091] Figure 5 Showing the axle 14 and Figure 4 Compared to the signal peak measured with a 5cm increase in spacing, that is, signal peak P2 at position A = 25cm, correspondingly, signal peaks P3, P5, and P6 also shifted by 5cm.

[0092] Figure 6 Showing the axle 14 and Figure 4 Compared to the measured signal peak value with a 15cm increase in spacing, that is, signal peak value P2 at position A = 35cm, correspondingly, signal peak values ​​P3, P5, and P6 also shifted by 15cm.

[0093] In comparison Figures 4 to 6 At that time, signal peaks P1 and P4 attracted attention. Despite height adjustment, they always had the same spacing A. Therefore, they must be reflected signals from components connected to chassis 11 in a fixed position. Because signal peaks P1 and P4 are constant, it can be easily determined by comparing the original signal dataset and... Figure 7 It is shown in isolation.

[0094] For altitude measurements using radar sensors, signal peaks P1 and P4 create interference, and are therefore referred to as background noise. Figure 7 As a background dataset, the signal peaks P1 and P4 of the background dataset are subtracted from all raw signal datasets generated during calibration driving. This operation is based on... Figure 4 Obtain the calibrated signal dataset, such as in Figure 8 The remaining signal peaks P2, P3, and P5 are shown. Similarly, from... Figure 5 Obtain the calibrated signal dataset, such as Figure 9 As shown. In this way, a separate calibrated signal dataset is generated for each altitude detected during the calibration drive, which no longer contains the signal peaks of the background dataset.

[0095] The corrected signal dataset can be cleaned up by removing signal peaks that are irrelevant to subsequent considerations. This cleaned and corrected signal dataset is referred to here as the peak dataset. The peak dataset contains at least the signal peak P2 from the axle 14, and in particular, also includes the signal peak P5 from the ground. Other selected signal peaks are advantageously retained. This simplifies rationality control. Alternatively, all signal peaks from the corrected signal dataset may be retained. The latter is also a peak dataset. An example of a peak dataset is shown below:

[0096] Measurement at the minimum air suspension setting (similar) Figure 4 )

[0097]

[0098] Theoretically, during calibration driving, the signal peak value P2 of axle 14 and the signal peak value P5 of ground 23 should change synchronously, provided that the pressure in tire 26 does not fluctuate. In reality, the spacing A may also change due to other reasons. For example... Figure 10 As shown, axle 14 is articulated, meaning that here the longitudinal control arm 27 pivots about a pivot point 28. Depending on the chassis geometry and the arrangement of sensors 19, related effects may occur.

[0099] In the example shown, assume a minimum spacing A1 between sensor 19 and axle tube 22. Axle tube 22 is not vertically positioned below sensor 19. Therefore, the vertical spacing VA1 between sensor 19 and axle tube 22 is significantly smaller. As the calibration driving height increases, axle tube 22 is in other positions, for example, with spacings A2 and A3 and corresponding vertical spacings VA2 and VA3. Based on the given conditions, the vertical spacings VA1, VA2, VA3 differ from spacings A1, A2, A3 and also have different relative spacings. Therefore, it may be meaningful to convert the spacing A contained in the corrected peak dataset (depending on the known chassis geometry and the arrangement of sensor 19) to the corresponding vertical spacing VA. The peak dataset thus generated is referred to herein as the linearized peak dataset and can be used in place of the peak dataset or additionally. The (linearized) conversion from spacing to vertical spacing is disclosed, for example, in EP 4 020 012 A1.

[0100] The linearization of signal peaks can also be performed at an earlier time point, that is, once it is determined which signal peak belongs to the axle 14.

[0101] Before calibration driving, it is unclear which signal peaks will belong to the axle 14 and the ground 23. It is basically assumed that the signal peak from the axle 14 has the highest intensity of all signal peaks because the axle tube 22 is relatively large and maintains only a small distance from the sensor 19. However, the surface of the axle tube 22 is curved, resulting in a weaker reflected signal compared to the case of a flat surface. Therefore, it may be meaningful for the radar reflector R to act on the axle tube 22 to ensure that the axle 14 generates the highest signal peak. This can be determined through pre-testing.

[0102] The signal peak intensity of ground 23 should be slightly lower, but still very noticeable, at least in a controlled workshop environment with a flat ground 23. Furthermore, in a controlled workshop environment, signal peaks with a larger spacing A compared to the signal peak of ground 23 should not occur. Using these precautions and considerations, at least the signal peak P2 of axle 14 and the signal peak P5 of ground 23 can be identified based on measurements taken during calibration driving. All other signal peaks either relate to additional components or to the aforementioned background.

[0103] Background signal peaks P1 and P4 can be determined by evaluating the raw signal dataset obtained during calibration driving. Irrelevant signal peaks outside the background dataset can be excluded, at least partially, by magnitude comparison. For example, during calibration driving, only the five highest signal peaks P1 to P5 in the raw signal dataset are retained, rather than the lower-intensity signal peaks. Alternatively, lower-intensity signal peaks are first excluded from the calibrated signal dataset, peak dataset, or linearized peak dataset.

[0104] After the entire calibration process is completed, the background dataset, as well as the peak dataset and / or the linearized peak dataset, are saved and can be used later during driving operations to determine the corresponding current height of the vehicle. In the saved peak dataset, the signal peak P2 for axle 14 can be identified and labeled. Each signal peak in the peak dataset, in addition to containing data on intensity I and spacing A, may also include a description of "axle signal peak," if applicable. Similarly, the signal peak P5 for ground 23 may be accompanied by a description of "ground signal peak."

[0105] After calibration, the current height should be continuously known during subsequent driving operations. To this end, sensor 19 is used to cyclically detect the current signal peak and generate a current peak dataset. The current height can refer to the distance between chassis 11 and axle 14, the distance between chassis 11 and ground 23, or other variable distances in the height adjustment mechanism of vehicle 10. Since the above distances can be easily converted to each other, for simplicity, the current distance aA or the current vertical distance aVA between sensor 19 and axle 14 is taken as the current height. The current distance aA is contained in or can be derived from each current signal peak of axle 14. Within the current peak dataset, the highest current signal peak is specifically assumed to be the current signal peak of axle 14.

[0106] Alternatively, the current signal peak of axle 14 can be determined based on its relative position to other current signal peaks, particularly relative to the current signal peak of ground 23 or other current signal peaks. The relative position of the current signal peak in the considered current peak dataset must be consistent with the relative position of the signal peak in one or more stored peak datasets. By comparing the current peak dataset with the stored peak datasets, the best-matching stored peak dataset can be determined. From this, the signal peak of axle 14, especially the signal peak of ground 23 and / or other signal peaks, is known and can be used as the current signal peak. The current signal peak of axle 14 can be identified at least by comparing the peak dataset with the current peak dataset.

[0107] After identifying the current signal peak of axle 14, the current distance aA between sensor 19 and axle 14 can be determined. Based on the current distance aA, the current vertical distance aVA can be calculated either taking into account the vehicle geometry and the arrangement of sensor 19 on chassis 11, or determined by incorporating a linearized peak dataset.

[0108] The following is a summary of the exemplary method steps for calibrating driving and subsequent driving operations.

[0109] Installation and calibration of sensor 19 during driving:

[0110] - Secure sensor 19 to chassis 11;

[0111] - Connect sensor 19;

[0112] - Sensor 19 generates the first raw signal dataset;

[0113] -Optionally: The highest signal peak value is determined as the axle signal peak value P2;

[0114] - Calibrate the drive to generate a raw signal dataset with all desired characteristics;

[0115] - Compare the original signal dataset to determine the background dataset;

[0116] - Generate calibrated signal and peak datasets;

[0117] - Determine the peak value of the vehicle axle signal P2 and the peak value of the ground signal P5;

[0118] -Optional: Determine the measurement range of the height adjustment mechanism;

[0119] - Generate a linearized peak dataset.

[0120] Driving operation after sensor 19 calibration:

[0121] - The vehicle needs to be started or powered on;

[0122] - Sensor 19 generates the current raw signal dataset;

[0123] - Generate the current peak dataset using the background dataset from the calibration drive;

[0124] -The highest current signal peak value is determined as the current axle signal peak value P2.

[0125] or

[0126] To determine the current axle signal peak P2, compare the current peak dataset with the peak dataset from the calibration drive;

[0127] -Optional: To check confidence, the peak value of the vehicle axle signal P2 and the peak value of the ground signal P5 from the peak dataset of the calibration drive are used;

[0128] -Optional: To check reliability, other signal peaks from the calibration drive may be used;

[0129] - Linearize the peak value P2 of the axle signal;

[0130] - Repeat the above steps in a loop.

[0131] The list of reference numerals is part of the instruction manual:

[0132] 10 vehicles

[0133] 11 Chassis

[0134] 12. Body Structure

[0135] 13 Axles

[0136] 14 Axles

[0137] 15 Axles

[0138] 16 Air Springs

[0139] 17. Air Spring

[0140] 18 Control Unit

[0141] 19 Sensors

[0142] 20 Lower side

[0143] 21 signal cone

[0144] 22 shaft tube

[0145] 23 Ground

[0146] 24-link

[0147] 25 Add-ons

[0148] 26 tires

[0149] 27. Longitudinal control arm

[0150] 28. Rotation point

[0151] aA spacing

[0152] A Current Spacing

[0153] A1 Spacing

[0154] A2 Spacing

[0155] A3 spacing

[0156] aVA Current vertical spacing

[0157] e Single peak

[0158] I Intensity

[0159] P1 signal peak value

[0160] P2 signal peak

[0161] P3 signal peak

[0162] P4 signal peak

[0163] P5 signal peak

[0164] P6 signal peak

[0165] R reflector

[0166] T0 time point

[0167] T8 time point

[0168] T14 time point

[0169] T16 Time Point

[0170] T28 time point

[0171] VA vertical spacing

[0172] VA1 Vertical Spacing

[0173] VA2 Vertical Spacing

[0174] VA3 Vertical Spacing

Claims

1. A method for measuring height in a vehicle (10) having a height adjustment mechanism, wherein, - A sensor (19) for measuring height is arranged on the chassis (11) of the vehicle (10) or connected to the chassis (11) at a defined interval. - The sensor (19) is arranged to detect the distance (A, aA) relative to the axle (14) of the vehicle (10) and, in particular, relative to the ground (23) below the vehicle (10). The sensor (19) sends signals toward the axle (14) and, in particular, the ground (23), receives reflected signals, and at least indirectly detects the intensity (I) of the reflected signals and the propagation time between the sent signal and the reflected signals, which are signal peaks (P1 to P6). - And the propagation time represents the distance (A, aA) of the sensor (19) relative to the axle (14) and, in particular, relative to the ground (23), or can be converted to the distance (A, aA). The feature is that, for calibration, the following steps are performed: a) The height adjustment mechanism controls the different heights of the vehicle (10). b) For each height controlled in step a), the propagation time and signal strength of the reflected signal are determined, thereby generating an original signal dataset for each controlled height, consisting of the propagation time and signal strength of the signal peaks (P1 to P6). c) Based on the propagation time and signal strength obtained in step b), identify the signal peaks (P1, P4) that always have the same propagation time regardless of the height driven out. d) The signal peaks (P1, P4) identified in step c) that always have the same propagation time together form a background dataset, which is stored for further use.

2. The method according to claim 1, characterized in that, The signal peaks of the background dataset are subtracted from the signal peaks of all original signal datasets to generate a corrected signal dataset for each original signal dataset, and the corrected signal dataset is stored.

3. The method according to claim 2, characterized in that, In each corrected signal dataset, identify the signal peaks (P2, P5) involving the axle (14) and, in particular, the ground (23), namely, the axle signal peak (P2) and, in particular, the ground signal peak (P5).

4. The method according to claim 3, characterized in that, At least the vehicle-bridge signal peak (P2) and, in particular, the ground signal peak (P5) of the corrected signal dataset are saved as a peak dataset.

5. The method according to claim 3 or 4, characterized in that, The peak value (P2) of the axle signal is determined by the following steps: e) For at least one height of the vehicle (10), compare multiple or all signal strengths (I) with each other to determine the highest signal strength. f) If the highest signal strength can be obtained, it is defined as a portion of the axle signal peak value (P2). g) If the highest signal strength cannot be determined, a reflector (R) shall be provided to the axle (14) to improve the reflection of the transmitted signal. h) After installing the reflector (R), repeat steps a) to c).

6. The method according to claim 5, characterized in that, The signal strength is selected as the highest signal strength if it is at least one limit higher than each of the other compared signal strengths (I).

7. The method according to claim 5 or 6, characterized in that, The following signal strength (I) is selected as part of the ground signal peak (P5): the signal strength has a propagation time that is a certain amount longer than the vehicle bridge signal peak (P2) and is also a certain amount longer than the adjacent signal strength.

8. The method according to any one of claims 4 to 7, characterized in that, The vertical distance (VA, aVA) relative to the axle (14) is calculated and stored by linearization based on the propagation time of the peak signal (P2) of the axle.

9. The method according to any one of claims 1 to 8, characterized in that, For calibration, two or more different heights are driven out.

10. The method according to any one of claims 1 to 9, characterized in that, For calibration, at least the minimum and maximum heights of the vehicle (10) must be controlled.

11. The method according to any one of claims 1 to 10, characterized in that, For calibration, all heights are controlled from the minimum height to the maximum height of the vehicle (10) or vice versa.

12. The method according to claim 10 or 11, characterized in that, The propagation time of the axle signal peak (P2) at the minimum height of the vehicle (10) and the propagation time of the axle signal peak (P2) at the maximum height of the vehicle (10) define the measurement range, and the measurement range is saved.

13. The method according to any one of claims 1 to 12, characterized in that, Radar sensors are used as sensors (19).

14. The method according to any one of claims 1 to 13, characterized in that, In particular, given the existing peak dataset and the existing background dataset, after the vehicle (10) is started, - Create at least one current raw signal dataset. - Calculate the current peak dataset to which it belongs by subtracting the existing background dataset. - Identify the current axle signal peak (P2) within the current peak dataset by comparing the current peak dataset with existing peak datasets or by selecting the highest current signal peak.

15. The method according to claim 14, characterized in that, Based on the propagation time of the current axle signal peak (P2), the current vertical distance (aVA) relative to the axle (14) is calculated by linearization.

16. The method according to claim 14 or 15, characterized in that, The reliability of the identified current axle signal peak value (P2) is checked as follows: - Check: Does the current peak dataset have a current ground signal peak (P5) that matches the identified current axle signal peak (P2) in terms of its propagation time and / or signal strength (I), or - Check: Does the current peak dataset have other current signal peaks (P1 to P6) that match the identified current axle signal peak (P2) in their propagation time and / or signal strength (I) direction? 17. The method according to claim 16, characterized in that, Based on the results of the credibility check, another current signal peak is selected as the current axle signal peak (P2) or, in particular, another height for the vehicle (10), and the steps specified in claim 11 are repeated.

18. A sensor (19) for measuring height in a vehicle (10), the sensor having software for performing the method according to any one of claims 1 to 17.

19. A control unit having software for performing the method according to any one of claims 1 to 17.

20. A vehicle (10) having a height adjustment mechanism, a chassis (11), at least one axle (14), a sensor (19) according to claim 18 or a sensor (19) for measuring height, and a control unit according to claim 19.

Images