Rain simulation system and method for testing the effects of weather on object detection by sensors

Description

[0001] The present invention relates to a rain simulation system for testing weather influences on object detection by sensors. The rain simulation system comprises a water supply device, in particular a water tank, a pump hydraulically connected to the water supply device for generating a supply pressure, at least one first nozzle arrangement hydraulically connected to the pump by means of at least one first piping system, at least one second nozzle arrangement hydraulically connected to the pump by means of at least one second piping system, and a control unit for controlling the nozzle arrangements. Furthermore, the invention relates to a method for testing weather influences on object detection by sensors, in particular environmental sensors of motor vehicles, using such a rain simulation system.

[0002] Modern vehicles are equipped with numerous sensors that assist the driver, for example, when parking, help maintain a distance from the vehicle in front, measure speed, or detect obstacles. These so-called environmental sensors are also essential for automated driving, as they must fully and reliably record the vehicle's surroundings. Examples of environmental sensors that can be used include ultrasonic sensors, cameras, radar, and lidar technologies, which detect the surroundings and initiate measures to avoid accidents and mitigate their consequences. However, interference from various weather conditions (rain, snow, or fog) is a major problem, as it impairs reliable object detection. Other vehicles or people may therefore be detected too late or not at all by the systems.It is therefore necessary to determine the reliable and critical functional range of such sensors in order to be able to use and improve them in a targeted manner. In such tests, it is essential to design the test conditions as realistically as possible and to avoid factors that could distort the test results. If possible, various weather scenarios should also be replicated.

[0003] CN 109 444 997 A describes a rain simulation device for use in research into soil erosion caused by rain. The flow rate of the individual nozzles can be varied by means of a disc with openings of varying sizes.

[0004] DE 10 2019 131 642 B4 describes a rain simulation device for testing driver assistance systems or corresponding sensors that can be attached to a test vehicle. For this purpose, one or more nozzle modules are attached to a belt that can be stretched around the rear of the vehicle. Each nozzle module has at least one nozzle. The opening angle, the spray cone angle, and the spray direction of the nozzles can be adjusted.

[0005] DE 10 2021 004 659 A1 discloses a mobile rain simulation device that enables location-independent simulation of various types of rain. In addition to dynamic vehicle tests, this system can also be used to validate and verify sensor systems under various environmental conditions. The rain simulation device comprises, in a conventional manner, a liquid tank, a pump, a distributor, and several pipe branches coupled to the distributor. Several nozzles are arranged at each of these pipe branches. With this rain simulation device, it is possible to change the setting angle of the nozzles, the angle of the frame supporting the nozzle arrangement, and the liquid pressure in order to simulate different types of rain. Although this rain simulation device can simulate different types of rain, it can only recreate some of the real rain characteristics.

[0006] From the subsequently published document WO 2024 / 103095 A1, a device for simulating rain for a motor vehicle test track is also known, which device includes a first group of nozzles of a first design type and a second group of nozzles of a second design type.

[0007] The object of the present invention is therefore to propose a rain simulation system and a method for testing weather influences on the object detection of sensors, with the aid of which several different rain characteristics can be simulated as realistically as possible.

[0008] The problem is solved with the features of the independent claims.

[0009] A rain simulation system for testing weather influences on object detection by sensors comprises a water supply device, in particular a water tank, a pump hydraulically connected to the water supply device for generating a supply pressure, at least one first nozzle arrangement which is hydraulically connected to the pump by means of at least one first piping system, at least one second nozzle arrangement which is hydraulically connected to the pump by means of at least one second piping system, and a control unit for controlling the nozzle arrangements.

[0010] It is proposed that the first nozzle arrangement comprises a first number of nozzles of a first design and the second nozzle arrangement comprises a second number of nozzles of a second design, wherein the nozzles of the first design and the nozzles of the second design each have a different volume flow at the same supply pressure. The first piping system includes at least one shut-off valve, and the second piping system also includes at least one shut-off valve. The at least one first nozzle arrangement and the at least one second nozzle arrangement can be controlled and / or supplied with water independently of one another by controlling the shut-off valves.

[0011] The advantages of the rain simulation system are also achieved with a method for testing weather influences on the object detection of sensors, in particular environmental sensors in motor vehicles, with such a rain simulation system, which is thus also claimed.

[0012] Furthermore, the use of such a rain simulation system is claimed for testing weather influences on the object detection of environmental sensors in motor vehicles.

[0013] By using two different nozzle types, it is possible to reproduce a very wide spectrum of rain intensity, which can include both very low rain intensities of, for example, 15 mm / h and very high rain intensities of, for example, 200 mm / h. In particular, however, the combination of two different nozzle types also makes it possible to reproduce a realistic and constant droplet size distribution. In other words, this makes it possible to generate rain events in which the drops that interfere with the sensor signals are always present in the correct number and size. The droplet diameters can thus be specifically adapted for use with certain vehicle sensors. This is important because the environmental sensors listed each emit the sensor signal at different wavelengths.The sensor signal is therefore disturbed to varying degrees depending on the wavelength, the number and size of the droplets, i.e. the droplet size distribution.

[0014] Another advantage is that the rain simulation system can also create standing fog.

[0015] It is advantageous if the rain simulation system includes a pressure control unit for regulating the supply pressure. This makes it possible, in contrast to simply adjusting the supply pressure, to generate rainfall events of varying intensity with a very high degree of temporal and, with appropriate nozzle arrangement, spatial homogeneity.

[0016] For pressure control, the pressure control unit preferably comprises at least one pressure sensor for measuring a pressure applied to the first and / or the second nozzle arrangement. In particular, with a pressure sensor designed as a pressure transmitter, it is possible to record the pressure applied to the nozzles in real time and feed it directly into the control unit. Delays can thus be avoided and the temporal homogeneity of both the rain intensity and the droplet distribution can be ensured. The at least one pressure sensor is preferably arranged close to the nozzle arrangements. Pressure losses that arise in long supply lines can thus be filtered out. For example, a pressure sensor can be arranged in a common supply line for the two nozzle arrangements immediately before the branching into the two nozzle arrangements.

[0017] Since in the rain simulation system the at least one first nozzle arrangement and the at least one second nozzle arrangement can be controlled and / or supplied with water independently of one another, only the first nozzle arrangement, only the second nozzle arrangement or both nozzle arrangements can be controlled or supplied with water in combination, thereby increasing the variety of rain characteristics that can be reproduced.

[0018] It is also advantageous if the rain simulation system's rain intensity can be adjusted, particularly between 15 mm / h and 120 mm / h, and preferably continuously. This allows all intensities of naturally occurring rain to be simulated. Thus, any desired rain intensity can be generated by the user.

[0019] According to a first embodiment, it is advantageous if the rain intensity can be varied by changing the supply pressure. For this purpose, for example, a control unit can store which rain intensity desired by the user requires which supply pressure. If the control unit includes a pressure control unit, the rain event can also be generated with a high degree of temporal consistency, as already described.

[0020] In this process, it is advantageous if the supply pressure of the supplied water is changed in order to continuously adjust the rain intensity.

[0021] It is also advantageous if the supply pressure can be adjusted within a range of 0.2 bar - 5 bar, preferably 0.2 bar - 3 bar. By specifying a minimum pressure, the nozzles can create a stable spray pattern with a constant and large clearance angle, which further contributes to the temporal and spatial homogeneity of the rain. On the other hand, by specifying a maximum pressure, the desired droplet size distribution can be ensured. For example, some nozzles tend to produce too many smaller droplets at high pressure, which makes it impossible to maintain the desired droplet size distribution.

[0022] According to another embodiment of the rain simulation device, which can be used in addition to or as an alternative to changing the supply pressure, it is advantageous if the rain intensity can be varied by selectively controlling only the first nozzle arrangement, only the second nozzle arrangement, or both nozzle arrangements simultaneously. Due to the two different nozzle designs, it is thus possible to reproduce a particularly wide spectrum of rain intensities with great homogeneity.

[0023] In this method, it is advantageous if only the nozzles of the first nozzle arrangement are controlled to generate rain with a low intensity. These nozzles preferably generate rain with an intensity of 15 mm / h - 40 mm / h, preferably 20 mm / h - 40 mm / h. For the nozzles of the first nozzle arrangement, a nozzle design is selected that provides a homogeneous spray pattern even at low flow rates.

[0024] It is also advantageous in the method if, to generate rain with a higher intensity, only the nozzles of the second nozzle arrangement are controlled, or if, to generate rain with a higher intensity, the nozzles of the first and second nozzle arrangements are controlled together. Rain with a higher intensity is preferably understood to mean an intensity of approximately 30 mm / h - 120 mm / h, preferably approximately 35 mm / h - 120 mm / h. For the nozzles of the second nozzle arrangement, a design is selected that can create a homogeneous spray pattern at higher volume flows.

[0025] According to an alternative embodiment of the method, it is advantageous if, to generate rain with a medium intensity, only the nozzles of the second nozzle arrangement are controlled, or if, to generate rain with a high intensity, the nozzles of the first and second nozzle arrangements are controlled together. Rain with a medium intensity is preferably understood to mean an intensity of approximately 30 mm / h - 70 mm / h, preferably approximately 35 mm / h - 60 mm / h. Rain with a high intensity is preferably understood to mean an intensity of 50 mm / h - 120 mm / h.

[0026] It is also advantageous if the first nozzle arrangement comprises nozzles with axial flow and the second nozzle arrangement comprises nozzles with tangential flow. It has been found that nozzles with tangential flow often require a larger volume flow to produce a uniformly distributed spray pattern, making them suitable for generating rain with higher intensity. In contrast, nozzles with axial flow also deliver a good spray pattern, especially at lower volume flows.

[0027] However, according to an alternative embodiment, it is also advantageous if the first nozzle arrangement comprises nozzles with a first nozzle diameter and the second nozzle arrangement comprises nozzles with a second nozzle diameter. The "nozzle diameter" refers to the bore diameter of the nozzle. This also makes it possible to generate a wide spectrum of different rain intensities with great homogeneity.

[0028] It is also advantageous if the nozzles of the first nozzle arrangement and / or the nozzles of the second nozzle arrangement are designed as full-cone nozzles. These have proven particularly advantageous for a homogeneous spray pattern. The spray angle preferably is as large as possible, at 120°.

[0029] It is also advantageous if at least the nozzles of each nozzle arrangement, preferably the nozzles of all nozzle arrangements, are arranged in a common, in particular horizontal, plane. This ensures that the raindrops produced have the same fall height and reach the same final velocity, so that the rain is produced under reproducible conditions. However, it is also possible to arrange the nozzles of the first arrangement, for example, on a different horizontal plane than the nozzles of the second arrangement. Particularly if the different nozzle types have different spray angles, such an arrangement can also produce homogeneous rain.

[0030] It is also advantageous if the nozzles of the first nozzle arrangement and / or the nozzles of the second nozzle arrangement are arranged in several rows, with the nozzles of one row being offset from the nozzles of the adjacent rows. It has been shown that this offset arrangement also allows for a particularly high level of local homogeneity of the rain, both in terms of intensity and droplet size distribution.

[0031] It is also advantageous if each nozzle within a nozzle arrangement has an individual distance from neighboring nozzles in the same nozzle arrangement, whereby the individual distance between each nozzle is determined as a function of the individual size of the nozzle's spray cone. The present invention has found that even nozzles of the same construction always have slightly different spray cones, e.g. due to only minimally different bore diameters. The size of the spray cone can be determined by tests before the nozzle is installed within the nozzle arrangement, and from this the individual distance between the respective nozzles can be determined. Fluctuations in the spray cones of the individual nozzles therefore do not affect the local homogeneity of the rain produced.

[0032] Also beneficial for a homogeneous spray pattern of the nozzles is a pipe length of at least 20 cm between a branch of a supply water line and the nozzle. This ensures a laminar flow to the nozzles, which supports a homogeneous intensity distribution across the irrigated area.

[0033] It is also particularly advantageous if at least one mesh is arranged beneath the nozzle arrangements to achieve a desired droplet size distribution. The invention has discovered that such a mesh can effectively filter out very fine droplets and also generate larger droplets that cannot be reproduced with the nozzles alone. The rain simulation system thus comes even closer to a natural droplet size distribution, which also includes a realistic proportion of comparatively large raindrops with a diameter of over 3 mm.

[0034] To achieve specific droplet sizes, it is also advantageous if the mesh is interchangeable, allowing different meshes with different mesh sizes to be used to adjust the desired droplet size distribution. This also helps to achieve the most realistic droplet size distribution possible.

[0035] In the method, it is accordingly advantageous if, in order to set a desired droplet size distribution, at least one net with a mesh size corresponding to the desired droplet size distribution is arranged below the nozzle arrangements.

[0036] It also offers advantages if the mesh is multi-layered and / or if several meshes are arranged one above the other. The droplet size distribution can also be influenced effectively by arranging multiple layers of mesh.

[0037] It is also advantageous if the first nozzle arrangement and / or the second nozzle arrangement are arranged at a height of at least 4 m, preferably at a height of at least 5 m, above the floor of the rain simulation system. It has been shown that such a drop height promotes the achievement of the desired or required final velocity of the drops.

[0038] It is also advantageous if the rain simulation system includes a decalcification system for decalcifying the water supplied to the rain simulation system. By removing the limescale from the water, the water used has a similar conductivity or refractive index to real rainwater, which further increases the quality of the tests conducted. This allows the limits of the sensors' functionality to be determined in a particularly realistic manner.

[0039] It is also advantageous if the rain simulation system has a disinfection station for disinfecting the water supplied to the rain simulation system. This prevents negative effects on the rain simulation system caused by film formation or residues, as well as health problems for users.

[0040] It is also advantageous if the nozzle arrangements cover an area of at least 80 m 2 , preferably at least 100 m 2 , and particularly preferably at least 150 m 2 . This allows measurements to be performed under realistic conditions, such as crossing objects, at different angles, and over different distances between the sensor and the object to be detected.

[0041] According to a further development of the invention, it is advantageous if the rain simulation system further comprises a light simulator. This allows different lighting effects to be generated to simulate oncoming vehicles, crossing vehicles, bicycles, or reflective objects.

[0042] According to another embodiment of the invention, it is advantageous if the rain simulation system further comprises a wind simulator. This allows different wind speeds from different directions to be introduced in a controlled manner. The direction of fall of the raindrops can thus be influenced and separately examined.

[0043] Further advantages of the invention are described with reference to the following exemplary embodiments. They show: Figure 1a rain simulation system for testing weather influences on object detection by sensors in a schematic overview, Figure 2 a top view of a segment of a rain simulation system with two nozzle arrangements, Figure 3 a top view of a rain simulation system with several segments, Figure 4 a schematic detailed view of a rain simulation system with a net, Figure 5 a schematic detailed view of another version of a rain simulation system, as well as Figure 6 a schematic representation of a rain simulation system according to a further embodiment with water treatment.

[0044] In the following description of the exemplary embodiments, identical features or features that are at least comparable in their design and / or mode of operation are provided with the same reference numerals. Furthermore, these features are only explained in detail when they are first mentioned, while the following exemplary embodiments only address the differences from the previously described exemplary embodiments. Furthermore, for reasons of clarity, often only one or a few of several identical components or features are labeled.

[0045] Figure 1shows a schematic overview of a rain simulation system 1 for testing weather influences on object detection by sensors 3. The rain simulation system 1 is installed in a fixed hall, so that external interference with the sensor testing can be largely excluded. However, a mobile application is also conceivable, in which the rain simulation system 1 is installed, for example, in a tent.

[0046] The rain simulation system 1 comprises, in a manner known per se, a water supply device 4, in this case in the form of a water tank 5, and a pump 6 hydraulically connected to the water supply device 4 for generating a supply pressure pz . The rain simulation system 1 further comprises a first nozzle arrangement 7a, which is hydraulically connected to the pump 6 by means of a first piping system 8a, and a second nozzle arrangement 7b, which is hydraulically connected to the pump 6 by means of at least one second piping system 8b. Furthermore, a control unit 9 is provided for controlling the nozzle arrangements 7. Finally, a pressure limiter 19 serves to limit the pump pressure.

[0047] The rain simulation system 1 is used here to test the influence of weather on the object detection of environmental sensors in motor vehicles 18. This is shown here as an example. A motor vehicle 18 is shown on the floor 26 of the rain simulation system 1 or the hall, which is equipped with a sensor 3 as an example. In reality, a motor vehicle 18 is of course equipped with a plurality of different sensors 3. Various types of sensors 3 are used, including ultrasonic sensors, cameras, lidar and radar sensors. An object 2 to be detected is also shown. Furthermore, arrows represent a measurement signal emitted by the sensor 3 and a measurement signal reflected by the object 2 or received again by the sensor 3. Under weather influences such as rain or fog, the measurement signal is attenuated by various physical effects such as absorption and transmission, reflection and scattering.As a result, sensors 3 can no longer reliably detect objects 2. For safety reasons, sensors 3 that are in a critical state should not be used as trigger criteria for automated processes. It is therefore necessary to use such tests to determine the reliable and critical functional ranges of sensors 3 and, in particular, to determine the operating point for each individual sensor 3 at which sensor 3 transitions from a reliable to an unreliable state.

[0048] The interference with the measurement signals caused by the aforementioned effects is highly dependent on the intensity of the rain or fog, as well as on the droplet diameter and the number of drops of that diameter. The intensity of the precipitation is given in mm / h, and the thickness of the fog in the meteorological visibility is given in m. Likewise, the interference with the measurement signals also depends on the properties of the individual sensors 3 themselves, such as wavelength and sensitivity. In order to be able to test a wide variety of sensors 3 as realistically as possible, a rain simulation system 1 should therefore allow both the intensity and the water droplet size and distribution of the precipitation to be set to different values. For reliable and reproducible test results, the rain intensity in each test case should also be as constant over time as possible and evenly distributed across the test area.

[0049] The rain simulation system 1 shown here therefore comprises nozzles 10a, 10b of various designs, which are attached to the ceiling 25 of the hall by means of suspensions 24. The first nozzle arrangement 7a comprises nozzles of a first design 10a, and the second nozzle arrangement 7b comprises nozzles of a second design 10b. The nozzles of the first design 10a and the nozzles of the second design 10b have different volume flow rates at the same supply pressure pz. It is therefore possible to reproduce almost the entire spectrum of naturally occurring rain with an intensity between 15 mm / h and 120 mm / h with very high homogeneity. For this purpose, the nozzles 10a, 10b are controlled and combined depending on the intensity selected. For example, to simulate low rainfall, only the nozzles of the first type 10a are controlled or supplied with water, and to simulate high rainfall, only the nozzles of the second type 10b are controlled or supplied with water.Likewise, to simulate very high-intensity precipitation, both nozzles of both types 10a, 10b can be controlled simultaneously. Furthermore, the intensity, as well as the droplet size, can also be varied by changing the supply pressure pz. For example, the supply pressure pz can be varied within a range of 0.5 bar - 2.0 bar.

[0050] The nozzle arrangements 7a, 7b are preferably arranged at a height H above the base 26, which allows most droplets to reach their final velocity. It has been shown that a drop height of approximately 5 m is optimal, since at this height, 90% of the droplets reach their final velocity.

[0051] In the present example, the nozzles of the first type 10a of the first nozzle arrangement 7a and the nozzles of the second type 10b of the second nozzle arrangement 7b are arranged in a common horizontal plane 13. This also contributes to a high uniformity of the rain produced.

[0052] The rain simulation system 1 shown here also has a pressure control unit 11, so that the supply pressure pz can not only be adjusted but also automatically adjusted. This further contributes to a high temporal consistency of the precipitation throughout the entire simulation process. The pressure control unit 11 includes a pressure control valve 27 and a pressure sensor 12 for measuring the pressure pd applied to the nozzles 10. The pressure limiter 19 also serves to adjust the specific control range of the pressure control unit 11.

[0053] The sensor signal of the pressure sensor 12 as well as the control signals for the shut-off valves 21 and the pressure control valve 27 are symbolized by dash-dotted lines. Various target values, such as the desired droplet distribution, the desired droplet size, and the intensity (in rain) or the visibility (in fog), can be set by user input on the control unit 9. The control unit 9 then controls the shut-off valves 21 of the nozzles 10a, 10b accordingly, and sets the supply pressure pz according to the target values. According to the present embodiment, this pressure is also controlled or adjusted throughout the entire simulation process.

[0054] Using the control system shown here, it is also possible to continuously adjust the supply pressure pz and, for example, to run specific irrigation programs. Manual adjustment is also possible.

[0055] In this case, the two piping systems 8a and 8b are supplied by a common supply line 23. It is understood that each piping system 8a, 8b could also be supplied by its own supply line 23. In this case, only one pressure sensor 12 is provided in the common supply line 23. However, a separate pressure sensor 12 could also be provided for each piping system 8a, 8b.

[0056] For a high local homogeneity of the rain at each intensity level, the arrangement of the nozzles 10a, 10b within the rain simulation system 1 is also important.

[0057] Figure 2shows a plan view of a segment 20 of a rain simulation system 1 with two nozzle arrangements 7a, 7b. For better differentiation, the nozzles 10b of the second nozzle arrangement 7b and the second piping system 8b are shown with dashed lines and slightly offset from the first piping system 8a and the second nozzle arrangement 7a. In order to achieve the most uniform control possible over the entire rain area, the nozzles of the first type 10a of the first nozzle arrangement 7a, as well as the nozzles of the second type 10b of the second nozzle arrangement 7b, are each arranged in several rows 14 with a lateral offset from one another. This results in an optimal coverage of the calculation area and thus also a very high local homogeneity of the generated rain, with a spray cone of the nozzles 10a, 10b that is uniform over 360°.

[0058] Again Figure 2As can also be seen, in each of the nozzle arrangements 7a, 7b, the offset arrangement of the nozzles 10a, 10b results in a triangular arrangement of the nozzles 10a, 10b relative to one another. As an example, such a triangle is shown in the bottom right of the image for each of the nozzle arrangements 7a, 7b by the distances A between the individual nozzles 10a, 10b. Ideally, three nozzles 10a, 10b each form an equilateral triangle. Since in reality each nozzle 10a, 10b forms a slightly different sized spray cone, even within a design, it may also be useful to individually adjust the distances A of each individual nozzle 10a, 10b to the surrounding nozzles 10a, 10b of the same design. The deviations of the side lengths of the "equilateral" triangle from one another are preferably less than 10%.This contributes to a geometrically well overlapping and homogeneous rain pattern and is therefore advantageous regardless of the specific design of segment 20 shown here.

[0059] The distances between the nozzles 10a, 10b can vary for each design, depending on the conical shape of the nozzles 10a, 10b. In this example, the nozzles of the first design 10a have a smaller distance A between them than the nozzles of the second design 10b. This also contributes to a very high local homogeneity of the rain at any desired intensity.

[0060] In the present case, the first nozzle arrangement 7a and the second nozzle arrangement 7b are arranged within the segment 20 in two half-segments 22, which are separated by the central water supply via the common supply line 23. In principle, however, the water supply could also be from the side. Furthermore, according to the present illustration, the nozzle arrangements 7a, 7b of each half-segment 22 can be individually shut off using a shut-off valve 21. However, a common shut-off for both half-segments 22 would also be possible.

[0061] Depending on the application, one such segment 20 may be sufficient for setting up a rain simulation system 1. However, to set up longer rain or fog stretches, it is also possible to arrange several such segments 20 one behind the other. This is shown in Figure 3which shows a top view of a rain simulation system 1 with several segments 20. It would of course also be conceivable to arrange several such segments 20 next to each other in order to create wider rain or fog sections.

[0062] The length of a segment 20, each comprising two half-segments 22, can be approximately 8 m, for example. If several such segments 20 are arranged in series, long rain and fog sections, for example, 50 m long, can be installed. If the width of the segments is also approximately 4 m, very realistic test conditions for vehicles can be created. This makes it possible to set up very large rain areas of more than 60 m² up to 200 m², thus creating realistic test conditions.

[0063] Figure 41 also shows a schematic detailed view of a rain simulation system 1 with a mesh 15 arranged below the nozzle arrangements 7a, 7b. Using such a mesh 15, the droplet size of the generated rain can be influenced and a desired droplet size distribution can be set. The mesh 15 is capable of filling very fine droplets and generating larger droplets from the smaller droplets. The mesh 15 can, for example, be attached directly to the piping systems 8 or to the suspensions 24 of the segments 20.

[0064] In order to adjust for different droplet sizes and different droplet size distributions, the mesh 15 is preferably interchangeable, and various meshes 15 with different mesh sizes can be used. It has been shown that, in particular, with finer meshes with a mesh size of less than 15 mm, preferably with a mesh size of less than 10 mm, even droplets with a diameter of, for example, 4 mm and more can be generated. In contrast, with the nozzle arrangements 7 alone, only droplets with a diameter of less than 3 mm can be generated. In order to achieve a droplet size distribution corresponding to real rain, which also covers larger droplet diameters, the arrangement of such a mesh 15 is therefore helpful.

[0065] To adjust the droplet sizes and droplet size distributions, it may also be helpful to arrange a multi-layered net 15 or to arrange several nets 15 on top of each other, as shown in Figure 5For example, the net 15 can be three-layered as shown in Figure 5 or four-layered.

[0066] In combination with the rain generation by two different types of nozzles 10a, 10b and by different pressures pa at the nozzles, droplets of the desired diameter can be generated. This is very useful for testing various sensors, since the attenuation of the measurement signal also depends on the droplet diameter of the rain.

[0067] Figure 6also shows a schematic representation of a rain simulation system 1 according to a further embodiment with water treatment. The rain simulation system 1 has a decalcification system 16, by means of which the limescale typically contained in tap water can be removed. The decalcification system operates according to the conventional principle of an ion exchanger and is therefore not explained in detail here. By removing the limescale, the refractive index of the drops largely corresponds to that of natural raindrops, so that no falsification of the measurement results is to be expected from the use of tap water.

[0068] According to the present illustration, the rain simulation system 1 further includes a disinfection station 17 for disinfecting the water supplied to the rain simulation system 1. A disinfectant can be added to the water by means of the disinfection station 17, so that the supplied water does not undergo any adverse changes due to contamination and the properties of the water are preserved.

[0069] For testing purposes, a rain event can also be created, for example, in which the intensity of the rain is continuously increased. For this purpose, only the first nozzle arrangement 7a is initially activated, and the pressure pa applied to the nozzles of the first type 10a is successively increased, for example, from 0.5 bar to 2 bar. The nozzle arrangement 7b remains deactivated.

[0070] To further increase the intensity of the precipitation, the first nozzle arrangement 7a is deactivated again when the final pressure value, in this example 2 bar, is reached, and the second nozzle arrangement 7b is activated. The pressure applied to the nozzles of the second type 10b is then successively controlled from 0.5 bar to, for example, 1 bar.

[0071] To further increase the intensity, both nozzle arrangements 7a, 7b are then operated jointly. If, as in the present examples, only one pump 6 and a common supply line 23 are provided for both nozzle arrangements 7a, 7b, the same pressure pa is applied to both nozzle arrangements 7a, 7b. The nozzle arrangements 7a, 7b are then also successively controlled from, for example, 0.5 bar to, for example, approximately 2 bar.

[0072] It is also conceivable to create a rain event in which the rain intensity is reduced from an initial high intensity value to a final low intensity value. Furthermore, it is also possible to specify a rain event with a certain constant intensity, which is maintained for several minutes, for example.

[0073] Preferably, the user only specifies the desired intensity or intensity range. Likewise, if several individually controllable segments 20 are present, the desired location within the rain simulation system 1 can be specified.

[0074] The control unit 9 can then independently adjust the supply pressure pz required for the desired intensity. The desired intensity can be entered directly into the control unit 9 by the user and changed as desired. However, it is also conceivable to store specific irrigation programs in the control unit 9, in which different locations and intensities are stored as target values within a rainfall event, which are then automatically set by the control unit by setting the corresponding supply pressure pz and activating the corresponding segments 20.

[0075] The method for testing the effects of weather on the object detection of sensors can therefore cover the entire spectrum of natural rain intensities, with the droplet size also being able to be optimized using different grids.

[0076] Using the described rain simulation system, it is possible to provide a spatially and temporally constant drop size distribution with very high homogeneity for each rain intensity and thus to carry out the tests in a very realistic manner. List of symbols

[0077] 1 Rain simulation system 2 Object 3 Sensor 4 Water supply device 5 Water tank 6 Pump 7 a First nozzle arrangement 7 b Second nozzle arrangement 8 a First piping system 8 b Second piping system 9 Control unit 10 a Nozzle of a first type 10 b Nozzle of a second type 11 Pressure control unit 12 Pressure sensor 13 Common level 14 Row 15 Network 16 Decalcification system 17 Disinfection station 18 Motor vehicle 19 Pressure limiter 20 Segment 21 Shut-off valve 22 Half-segment 23 Supply line 24 Suspension 25 Ceiling 26 Floor 27 Pressure control valve pz Supply pressure pd Pressure applied to the nozzles A Distance between nozzles H Height

Claims

1. Rain simulation system (1) for testing weather influences on object detection by sensors (3), in particular by surroundings sensors of motor vehicles (18), having a device for supplying water (4), in particular a water tank (5), having a pump (6), which is hydraulically connected to the device for supplying water (4), for the generation of a supply pressure (pz), having at least one first nozzle arrangement (7a), which is hydraulically connected to the pump (6) by means of at least one first pipeline system (8a), having at least one second nozzle arrangement (7b), which is hydraulically connected to the pump (6) by means of at least one second pipeline system (8b), and having a control unit (9) for controlling the nozzle arrangements (7a, 7b), wherein the first pipeline system (8a) contains at least one shut-off valve (21) and wherein the second pipeline system (8b) contains at least one shut-off valve (21), and wherein the at least one first nozzle arrangement (7a) and the at least one second nozzle arrangement (7b) can be controlled independently of one another and / or charged with water by controlling the shut-off valves (21), characterized in that the first nozzle arrangement (7a) comprises a first number of nozzles of a first type (10a) and the second nozzle arrangement (7b) comprises a second number of nozzles of a second type (10b), wherein the nozzles of the first type (10a) and the nozzles of the second type (10b) each have a different volume flow at the same supply pressure (pz).

2. Rain simulation system (1) according to the preceding claim, characterized in that a rain intensity of the rain simulation system (1) can be set, preferably can be set between an intensity of 10 mm / h and 200 mm / h and particularly preferably between an intensity of 15 mm / h and 120 mm / h, wherein the intensity can preferably be set continuously.

3. Rain simulation system (1) according to the preceding claim, characterized in that that the rain intensity can be changed by changing the supply pressure (pz) and / or in that the rain intensity can be changed by selectively controlling only the first nozzle arrangement (7a) or only the second nozzle arrangement (7b) or both nozzle arrangements (7a, 7b) simultaneously.

4. Rain simulation system (1) according to one of the preceding claims, characterized in that the first nozzle arrangement (7a) comprises axially impinged nozzles (10a) and the second nozzle arrangement (7b) comprises tangentially impinged nozzles (10b), wherein the nozzles of the first type (10a) of the first nozzle arrangement (7a) and / or the nozzles of the second type (10b) of the second nozzle arrangement (7b) are preferably designed as full-cone nozzles.

5. Rain simulation system (1) according to one of the preceding claims, characterized in that at least the nozzles (10a, 10b) of a respective nozzle arrangement (7a, 7b), preferably the nozzles (10a, 10b) of all nozzle arrangements (7a, 7b), are arranged in a common, in particular horizontal, plane (13).

6. Rain simulation system (1) according to one of the preceding claims, characterized in that the nozzles of the first type (10a) of the first nozzle arrangement (7a) and / or the nozzles of the second type (10b) of the second nozzle arrangement (7b) are arranged in multiple rows (14), wherein the nozzles (10a, 10b) of a row (14) are each arranged offset with respect to the nozzles (10a, 10b) of the adjacent rows (14), wherein three nozzles of a type (10a, 10b) are preferably each arranged in the form of a triangle.

7. Rain simulation system (1) according to one of the preceding claims, characterized in that, in order to set a desired droplet size distribution, at least one net (15) is arranged below the nozzle arrangements (7a, 7b), wherein the net (15) is preferably of multilayer design and / or multiple nets (15) are arranged one above the other.

8. Rain simulation system (1) according to one of the preceding claims, characterized in that the first nozzle arrangement (7a) and / or the second nozzle arrangement (7b) are arranged at a height (H) of at least 4 m, preferably at a height (H) of at least 5 m, above a ground (26) of the rain simulation system (1).

9. Rain simulation system (1) according to one of the preceding claims, characterized in that the rain simulation system (1) has a decalcification system (16) for decalcification of water supplied to the rain simulation system (1) and / or in that the rain simulation system (1) has a disinfection station (17) for disinfection of water supplied to the rain simulation system (1).

10. Use of a rain simulation system (1) according to one or more of the preceding claims for testing weather influences on the object detection of surroundings sensors of motor vehicles (18).

11. Method for testing weather influences on the object detection of sensors (3), in particular of surroundings sensors of motor vehicles (18), with a rain simulation system (1) according to one of claims 1-9.

12. Method according to the preceding claim, characterized in that, in order to generate rain with a low intensity, only the nozzles of the first type (10a) of the first nozzle arrangement (7a) are controlled.

13. Method according to one of the two preceding claims, characterized in that, in order to generate rain with a higher intensity, only the nozzles of the second type (10b) of the second nozzle arrangement (7b) are controlled, or in that, in order to generate rain with a higher intensity, the nozzles (10a, 10b) of the first and the second nozzle arrangement (7a, 7b) are controlled jointly.

14. Method according to one of the preceding method claims, characterized in that, in order to generate rain with a medium intensity, only the nozzles of the second type (10b) of the second nozzle arrangement (7b) are controlled, or in that, in order to generate rain with a high intensity, the nozzles (10a, 10b) of the first and the second nozzle arrangement (7a, 7b) are controlled jointly.