Backlight-dependent cleaning of an optical window of an optical sensor for detecting the surroundings of a motor vehicle

Abstract

The invention relates to a device and a method for cleaning an optical window of an optical sensor for detecting the surroundings of a motor vehicle. Optical radiation from the surroundings of the motor vehicle passes through the optical window. The core of the invention is that the cleaning process is dependent on at least one property of the optical radiation. The present invention thus presents an automated cleaning system that incorporates the backlight situation into the planning of the cleaning process.

Description

The present invention relates to a method and apparatus for cleaning an optical window of an optical sensor for detecting the environment of a motor vehicle according to the features of the independently formulated claims.Prior ArtOptical sensors for detecting the environment are an integral part of many autonomous and semi-autonomous systems. Depending on the conditions of use and availability requirements, these sensors may be equipped with cleaning devices for keeping them free (typically for precipitation) and washing (typically for fouling).Examples of optical sensors for detecting the environment are cameras and lidars. Cameras are passive sensors that are primarily sensitive in the range of visible light (350 nm to 800 nm). Lidars operate as active sensors primarily in the near infrared / NIR range (800 nm to 2500 nm), cost-effective lidars, especially in the range 800 nm to 1000 nm. The optical frequency bands are dominantly affected by the spectrum of sunlight.Examples of automated systems with optical environment detection can be found, inter alia, in goods and people transportation by means of any form of vehicle (air, water, country). In particular in the motor vehicle sector, there is a trend toward increasing support and automation of the driving operation, inter alia in the sector of level 3 / 4 / 5 automation (see SAE level 4). Cleaning systems address one of the central challenges of increasing automation: represent a safe behavior with sufficient availability. The higher the degree of automation, the more the human is taken from the safety responsibility and the less is it available as a fallback level for a partial or complete system failure. For example, starting from SAE level-3, the driver is no longer required to monitor the vehicle guidance at the up-time of the system, and starting from SAE level-5, there is no longer any possibility for vehicle occupants to take over the vehicle guidance again.Both relevance and design of cleaning devices also depend considerably on the planned operating conditions (operational design domain). In order to maintain functions despite external sensor faults due to rain or dirt, for example, cleaning operations during driving must be possible. Depending on the automation level, these cleaning operations must be triggered without human intervention.The standard cleaning solution in vehicles currently consists of windshield wipers with water application for front and rear windows. During a wet cleaning process, the water is applied to the windshield either by means of separate spray nozzles or by means of spray nozzles integrated in the wiper and removed again from the wiper blade. In this case, the wet and dry cleaning processes are controlled manually via the steering column of the vehicle. In addition, in modern wiping-washing systems, the windshield wiper can be triggered at an adequate speed by a total-reflection-based rain and dirt sensor.In addition, there are a number of cleaning systems (especially in vehicles of higher automation levels), which are also partially automatically controlled. Examples are:• Wipe-Wash Systems for Lidars• Water Intensive Washing Systems for Lidar and Video Sensors.Further known cleaning systems are based, for example, on the action of centrifugal force or ultrasound.Furthermore, heating systems are used on sensors (e.g. on the lens or protective glasses) or in the further optical path (e.g. on the windshield) in order to eliminate disruptive condensation or icing.DE 102019209291A1 proposes a method for the automated cleaning of at least one environment sensor of an environment sensor system of an autonomous vehicle, the environment sensor being designed as an imaging sensor, for example as a video camera or as an imaging radar sensor or as an imaging lidar sensor. This method comprises the following steps:• Generating image data from an image of a vehicle environment by means of the environment sensor;• Analyzing the image data and detecting dirt• the environment sensor based on the analysis;• Evaluation of fouling based on analysis;• Initiation of measures depending on the evaluation, wherein the analysis of the image data and / or the detection of a contamination of the environment sensor and / or the evaluation of the contamination is carried out by means of a neural network.Disclosure of the InventionThe invention relates to a device and a method for cleaning an optical window of an optical sensor for detecting the environment of a motor vehicle. The optical radiation from the environment of the motor vehicle passes through the optical window.The essence of the invention is that the cleaning takes place at least depending on at least one property of the optical radiation. The present invention thus shows an automated cleaning system which also includes the counter light situation in planning the cleaning process.The invention is based on the following finding:The blindness of optical sensors due to scattering media in the optical path can be considerably increased by counter light. In particular, the brief interference of a sensor due to a cleaning / washing process by counter light can be considerably increased and extended.Scattering media in the counter light:Water and other contaminants in the optical path of an optical sensor may result in partial or complete blindness of the sensor. In the case of scattering media, this fading effect can be substantially enhanced by counter light sources. The reason for this is that the counter light is further scattered in the direction of the sensor; this will be described in more detail with reference to FIG. 2. In this case, the interference light source does not necessarily have to lie in the direct field of view of the sensor (indirect counter light).The counter light, which is scattered in the direction of the optical sensor, can produce disturbances and sensor blindness in various ways.Thus, the transparent surface (the optical window) which protects the sensor from weathering influences (for example: windshield, outer optical element of a surround-view camera), is generally not situated in the focal region of the sensor. Small water drops or contaminations are therefore hardly visible to the sensor under normal lighting conditions, since they are mapped onto a large circle of scattering: edges and contours become blurred and the superimposed interference light input is relatively small due to the distribution effect. Under the influence of back light, however, the disturbance light entry in the entire area of the scattering circles can dominant the scene light (see FIG. 3 ). The qualitative active relationships can be summarized as follows: 1. the more intense the counter light, the more intense the disturbance light entry, the poorer the ratio of useful light to disturbance light (useful light: scene light, disturbance light: light scattered and defocusing by the dirt in the direction of the camera, see FIG. 3 a ). 2. the larger the scattering circle, the more intense the counter light must be for a relevant disturbance, but the more extensive the disturbance effect is also.Another example is thin water layers. Since water hardly absorbs in the visible light range, they act, inter alia, as an additional optical element. The more homogeneous the water layer, the less destructive it has to the background. In particular, objects may be still readily recognizable under certain circumstances. In the case of strong counterlight, on the other hand, even very small inhomogeneities lead to a strong disturbance light entry in the direction of the camera and thus to a superimposition of the scene structures.The generally additional light input can lead to further glare effects in the sensor. Inter alia, photons can generate further disturbances in all photo detectors due to multiple scattering in the sensor. In addition, the sensor can come to the limits of its dynamic range, so that darker regions can only be insufficiently resolved.The described droplets and thin water layers can occur not only as a result of external influences, but also in the context of and as a residue of a sensor cleaning.The influence of counter light on the need for cleaning:As described, back light can lead to considerable sensor interference even due to small amounts of scattering media in the optical path. This results in an increased or earlier cleaning requirement in the case of counterlight. This relationship can be described not only categorically but also continuously: the more back light, the more the amplification of blindness, the higher the cleaning requirement.One example is an increased need for liberation in the case of precipitation. Both the first droplets of a precipitate already lead to a need for clearance and a more rapid removal is necessary, for example also for the residues of a wiping process. Overall, with an identical precipitation quantity, the required clearance intensity (e.g. wiper speed, rotational speed, duration and intensity of an air flow) is higher in the case of counterlight than without counterlight (similar to a speed-dependent cleaning requirement).A further example is a changed need for cleaning contaminants, which results from the increased sensitivity to contaminants in the case of back light. For example, even thin dust layers or small salt residues due to back light can become a problem, so that cleaning in the case of back light can be worthwhile in cases in which no need for cleaning would be present without back light.Influence of Counterlight on Washing Processes:Also in the context of washing processes (i.e. wet cleaning), media which scatter briefly with the cleaning liquid are found in the optical path. This leads in almost all cases to a temporary disturbance of the sensor. As motivated above, the duration and intensity of this disturbance can be increased considerably by a counter light situation. In particular, even slight water residues, such as water films or small droplets, can still lead to strong blindness effects and considerably lengthen the duration of critical blindness. In addition to a generally resulting deterioration in the system performance, it is probable that in the case of back light, a classic cleaning behavior leads to critical degradation of the (at least one) sensor and therefore essential system functions must be degraded. In the context of autonomous driving, for example, this may mean a restriction on system availability (e.g. emergency stop) that can be intensively exhibited by the customer.The problem is exacerbated in that in some positions and forms of installation, and possibly also for cost reasons, cleaning technologies with minimal water input (such as, for example, aquablads) cannot be equipped for each sensor. This makes consideration of the matter in the cleaning control essential.Advantageously, it is provided according to the invention that optical radiation consists of at least two radiation components, wherein• a first radiation component by scattering photons on objects in the environment of the motor vehicle (indirect radiation component), and• a second radiation component, the described counter light / direct radiation component, by radiation sources actively emitting optical radiationThe optical radiation is generated in the second radiation component and the property of the optical radiation, depending on which the cleaning takes place, is determined.In one embodiment of the invention, the cleaning takes place at least as a function of at least one instantaneous and / or one future property of the optical radiation, in this case the aforementioned second radiation component, the counter light, is meant in particular.The invention is thus a cleaning system for optical sensors ("addressed sensors"), which automatically incorporates information regarding the currently determined or future expected back light situation into the configuration of the cleaning behavior in order advantageously to increase the availability of at least one addressed sensor. Other cleaning-relevant signals are still included in the cleaning control. Classic design factors such as resource consumption and cleaning performance can therefore still be taken into account.The cleaning system and the addressed sensors can be part of a larger autonomous or partially autonomous system in which the cleaning system serves to improve system availability and / or safety.The cleaning according to one embodiment of the invention takes place at least depending on at least one property of the optical radiation in such a way that the start of the cleaning is selected at least depending on at least one property of the optical radiation. Here too, the second radiation component described above, the counter light, is meant in particular.In a very advantageous embodiment of the invention, it is provided that the cleaning takes place at least as a function of at least one property of the optical radiation in such a way that the motor vehicle is controlled in such a way that the property, the described counter light, of the optical radiation is influenced during the cleaning.In a first embodiment of this variant, it is provided that the cleaning takes place at least depending on at least one property of the optical radiation, the described counter light, in such a way that• a cleaning which is currently running or imminent is determined, and• controlling the motor vehicle in the sense that a property of the optical radiation optimized for cleaning is achieved during the ongoing or the imminent cleaning.In a further embodiment of this variant, it is provided that the cleaning takes place at least depending on at least one property of the optical radiation, the described counter light, in such a way that• determining the need for cleaning; and• at least one time period is determined in which the motor vehicle is positioned in such a way that a property of the optical radiation optimized for the cleaning is achieved, and• the cleaning determined as necessary takes place in the determined time period.In a further embodiment of this variant, it is provided that the cleaning takes place at least depending on at least one property of the optical radiation, the described counter light, in such a way that• determining the need for cleaning; and• the motor vehicle is controlled in such a way that a property of the optical radiation optimized for cleaning is achieved at least in a time period, and• the cleaning determined as necessary takes place in the determined time period.In the embodiments described in the preceding paragraphs, the back light information is additionally or exclusively included in the behavioral layer of an autonomous system, the vehicle. The cleaning of the optical sensor addressed at least by the cleaning and affected by the opposing light is integrated into the travel planning of the vehicle. A prerequisite for this is that this system can influence the transmitted light, for example by route planning or maneuver planning. The variants already described are to be considered according to the invention:The behavior layer minimizes the counter light at the given cleaning time:The cleaning system informs the behavioral layer of ongoing or pending cleaning. The behavioral layer attempts to minimize the back light for the at least one addressed sensor at the cleaning time by the overall system behavior. The behavior layer cannot directly influence the type and the time of cleaning. Moreover, for this purpose, the cleaning system does not necessarily itself have to take account of the counterlight in the cleaning behavior, but the cleaning per se also takes place in this variant depending on the counterlight, since the vehicle is controlled in such a way that optimized counterlight conditions are present during the cleaning.The behavior layer and cleaning system jointly optimize:The cleaning system informs the behavioral layer of an outstanding need for cleaning. The behavioral layer checks its currently scheduled behavior, adjusts it optionally / as needed, and provides feedback over appropriate periods of time for cleaning. The balancing of a prompt cleaning compared to a time with minimal counterlight can then be suitably carried out.In an advantageous embodiment, the property of the optical radiation, in particular the second radiation portion (counter light), can be effected by radiation sources actively emitting optical radiation, by the sensors to be cleaned or by further sensors.It should be noted at this point that the term "cleaning" is used for any form of active reduction of disruptive media (e.g. dirt, precipitation or mist) in the sensor path using, for example, dry-mechanical and / or wet-mechanical and / or chemical and / or thermal means. Furthermore, the term "clean" can also encompass keeping free in the event of precipitation and eliminating fogging or icing.Further advantageous embodiments of the invention can be taken from the dependent claims and the exemplary embodiment.DRAWINGSAn exemplary embodiment of the invention is explained in more detail on the basis of the figure and the following description.FIG. 1 shows a vehicle with a sensor system.FIG. 2 schematically shows the light conditions in the vicinity of a sensor.Figures 3a, 3b and 3c show images / photos of different lighting conditions.FIG. 4 shows a sequence of an exemplary embodiment of the invention.Environment sensor system 1 is set up to capture an environment U of vehicle 10 and to generate environment image data. For the detection of the environmental image data, the environmental sensor system 1 comprises a first environmental sensor 20 which is configured to generate image data from a first image of the environment U. Environment sensor system 1 also includes a second environment sensor 30, which is set up to generate image data from a second image of surroundings U. The two sensors 20, 30 are arranged at a front region of the vehicle 10 in the direction of travel A. In addition, the two environment sensors 20, 30 are optical sensors which, in the preferred exemplary embodiment, are designed as lidar sensors. The sensors 20 and 30 or one of these sensors mentioned by way of example can also be a camera; the position of the optical sensors on the vehicle can likewise also deviate from that in FIG. 1.The vehicle 10 further comprises a cleaning device 80 for cleaning the surfaces of the environment sensors 20 and 30, in particular the optical windows through which the optical radiation, in particular the ambient light, enters or exits. However, it should additionally be pointed out that there may be cleaning solutions controlled differently centrally or in a decentralized manner for different positions. A solution may address multiple sensors (e.g., behind the windshield). This means that all assignments and networking between cleaning systems and sensors are possible.In this example, cleaning device 80 is situated above surroundings sensors 20 and 30, and includes at least one spray nozzle through which water or another cleaning liquid may be sprayed onto the surfaces of one or both surroundings sensors 20, 30, in order to eliminate contamination of surroundings sensor 20, 30. For example, there is cleaning with a particularly sparse air-water mixture, wherein the spray nozzle can optionally spray only air or an air-water mixture.Perhaps we want to mention thisEnvironment sensor system 1 also has a computing unit 40, which is set up to analyze the environment image data. For this purpose, object detection is carried out on the basis of the surroundings image data. The information resulting from this object detection is provided to a control device 50 of the vehicle 10.The control device 50 is configured to control the vehicle 10 autonomously or at least partially autonomously in the sense of a driver assistance.When operating the vehicle 10, i.e., in particular during a driving operation, adverse effects on the environment sensor system 1 may occur, due to contamination due to environmental effects of the first sensor 20 and / or the second sensor 30.In FIG. 2, reference numeral 20 denotes a sensor, and reference numeral 26 denotes an optical window through which the ambient radiation / light reaches the sensor 20. Both the direct "useful light" 21, i.e. the useful light from the objects, and the light radiation 22 which emits from strong interference radiation sources reach the sensor 20 via the window 26. The "scene light" or useful light 21 from the object is disturbed by the counter light 22, which predominates in the radiation superimposed by scattering.Summarizing the terms in FIG. 2 :• 21: scene light: useful light of objects for transporting structural information of the environment, i.e. useful for environment detection• 22: back light / strong light source• 23a and 23b: Media on the optical windowThe counter light 22 is scattered into the optical path in the direction of the sensor 20 through the media 23 aand 23 b, so that the radiation 21 is overlaid by radiation 22. This results in a reduced signal-to-noise ratio (SNR), which is why the component 22 is also interpreted as a "disturbance light source" in this context.Liquid / water drops 23 aor a liquid / water film 23 bor other contaminations are generally formed on the surface of the optical window 26 directed towards the environment. This water and these contaminations in the optical path scatter the radiation arriving through the optical window 26 in the direction of the sensor 20, among other things. In the case of a strong interference light source, the scattered light 25 can overlap relevant object light 21. This effect can be considerably enhanced, for example, by a defocus on the surface concerned, since contamination beyond its geometrical angular range interferes.As previously described, water 23 and other contaminants in the optical path of an optical sensor 20 may result in partial or complete blindness of the sensor 20. In the case of scattering media, this fading effect can be considerably enhanced by back light sources (direct and / or indirect back light 22). The reason for this is that the counter light is further scattered in the direction of the sensor 20 (scattered radiation 25),FIGS. 3 a, 3 band 3 c show specific examples of the above-described physical effects.FIG. 3 ashows a photograph of a camera mounted behind a strongly defocusing windshield. FIG. 3 ashows small water drops which become visible by the counter light in the entire circle of scattering of the defocusing camera and superimposes the scene recorded by the camera until the non-characteristic. Without counter light, the water drops would hardly be perceptible and the scene would be readily visible.FIG. 3 bshows a water film or water drop recorded by a near-field camera with a fisheye lens. Without strong counter light from the sun, the scene in the center of the image would also be easily recognizable here.Figure 3c shows the photograph taken by a camera subjected to direct sunfade. The sunlight converts very small inhomogeneities in and at the optical window to strong disturbance entries.FIG. 4 shows a block diagram for describing a specific exemplary embodiment of the invention, how the information regarding disturbing counter light for one or more sensors to be cleaned is taken into account automatically in the cleaning behavior.Blocks 42 and 43 again show only one interface with the input variables of block 44.In block 41, the back light is estimated:In order to control the cleaning of one or more optical sensors as a function of counter light, counter light must be estimated / measured and / or anticipated in each case.For estimating the current counter light, for example, one or more optical sensors can be used, optionally also those which are addressed by the cleaning system. For example, a direct glare situation in a camera image (see FIG. 3 c ) can be reliably effected by counting saturated or nearly saturated pixels. Depending on the control over the camera control and basic signal processing in imager and digital preprocessing, (additionally or alternatively) a rough photometric measurement of the light source can be possible and helpful. Glare detection can also be realized in a similar manner in most lidar models.In order to detect back light situations, dedicated brightness sensors can also be used, i.e. sensors which are not addressed by the cleaning.If a plurality of optical sensors are installed in a known position and orientation with respect to one another (extrinsically calibrated), and the light source can be sufficiently localized, then a conclusion can also be drawn about a possible direct or indirect glare in the other sensors by detecting direct glare in one or more of the sensors.Furthermore, the detection of direct or indirect blending can also be carried out or supported on a classification basis.For the assessment of the current or expectation of the future back light situation, a spatio-temporal localization (e.g. via use of landmarks, GPS sensors or ego-motion information) and a modeling of localized light sources (e.g. sun) can also take place. Information on the surrounding geometry (building, road shape, vegetation,... ) can also be included. For predicting the rear light situation, information and assumptions about planned short-term maneuvers (e.g. trajectories) and / or long-term maneuvers (e.g. navigation) can furthermore be used.Furthermore, status information relating to the transmitted light source can also be included (e.g. vaulting information in order to evaluate the current influence of sunlight).In addition to distinct back light cases, situations with little back light can also be detected or anticipated explicitly. This allows strategies for low-back light cleaning (see below).All information may come from internal or external system sources (e.g., an overdos condition detected by internal sensors, or from external weather service).The information about the counter-light situation (or indirect auxiliary signals) can also be used for other purposes in the overall system or can also be determined exclusively for the cleaning system.The determination of the current or future back light situation is typically based on estimation methods and may be error-prone.The determination can pass on one or more arbitrarily distributed control devices and can pass through arbitrary aggregation / composition stages.Summarizing, in block 41, a current assessment is thus carried out by means of one or more optical sensors (optionally including the cleaning affected sensor / s). Furthermore, a prediction can take place taking into account the imminent driving maneuvers and / or navigation steps, etc.In block 42, the counter light measure is determined:The information about the current or future back light situation must be described in one or more measures in order to be made available at one or more interfaces of the cleaning controller. An interface can also be internal to the control device, for example if the tail light determination is integrated / combined with the control. The block 42 is only the interface, i.e. it describes the counter light determined in 41. The block 42 relates primarily to possibilities for coding the transmitted light information.The information regarding the counter light situation can describe, for example, the presence and / or number and / or type and / or extent and / or localization and / or angle of incidence and / or luminance (and / or equivalent photometric variables) of interference sources in the intake region of the sensors. It can also be described as any discretized distribution (e.g. of brightness or intensity values). In the case that the counter light situation is dependent on the sensor alignment (e.g. whether a localized light source is in the intake area of a sensor or not), the information can distinguish according to sensors or groups of sensors, e.g. as information per sensor or cleaning position.A description of the back light situation at time intervals is also favorable, in order to describe, for example, good or poor time periods for cleaning operations, and to enable optimized planning (see below).In summary, the block 42 describes the counter light measure ascertained in 41, for example by a glare flag, a luminance histogram, a disturbance source list, a counter light prediction, time intervals.In block 43, further control-relevant input variables to block 44 are shown, such as precipitation intensity, speed, degree of stretching, external cleaning requirement, etc.Block 44 shows the control of the back light dependent cleaning:The core consists in including the ascertained back light information in the cleaning controller in order to thereby include a safety and / or availability advantage in at least one of the above-mentioned. To achieve Challenge Contexts. Possible strategies in the challenge context of a changed cleaning requirement in the case of rear light are: 1. increase the release intensity: the intensity of a release program (wiper speed, rotational speed, etc.) is typically regulated as a function of the precipitation quantity and occasionally also as a function of the intrinsic speed. In order to meet an increased cleaning requirement in the case of precipitation in the case of glare, the keep-free intensity can additionally be increased as a function of the transmitted light. In this case, the improved system availability can be balanced against a higher resource consumption (power consumption and wear). In particular, this strategy can be used both in fully autonomous cleaning systems and in cleaning requested by humans (e.g. by steering column of the driver). 2. anti-light cleaning: In the case that an intensive anti-light situation is expected in the near future, an anti-light cleaning of the at least one affected sensor can be performed in order to minimize unnecessary scattering at the anticipated anti-light time. This can be effected, for example, by a washing program for removing even light dirt and / or a heating program for removing even light water residues.In order to reduce the number of unnecessary preventive cleanings and to conserve resources, the control can additionally be made dependent on a detection or estimation of light soils. Detection can be effected, for example, by a lower-threshold blindness detection of the sensor, and estimation can be effected, for example, by assumptions about the accumulation of dirt over time and / or driving situations.Possible strategies in the challenge context of counterlight washes are as follows:• Cleaning are delayed: In order to avoid wet cleaning in the case of counterlight, the planned washing process can be suspended. The urgency of the planned cleaning can be balanced against the intensity of the counter light. The urgency can be determined, for example, by a detected degree of contamination.• To perform cleaning: If an anticipating estimate of the counter light is present, a cleaning preference can also be considered in a similar manner to delaying. This behavior can be preventive, e.g. if there is actually not yet sufficient contamination for a normal washing process, or coordinative, if e.g. a planned washing process is already planned on the basis of a maintenance cycle and / or a defined processing sequence, but only for a later point in time.• Adjust cleaning program: In order to reduce the scattering effects of strong counter light in a washing program in terms of time and location, the parameterization of the cleaning can also be adjusted. For example, more intensive (and thus faster and more thorough) drying can be carried out with more counter light, e.g. with a wiping device by more rapid, more frequent or longer lasting wiping. Furthermore, for example, the amount of the cleaning liquid applied can also be reduced (e.g. over the introduction time or intensity), up to an exclusive dry cleaning. Alternatively, the application of the liquid can also be changed if this proves to be beneficial in the counter lighting context, but otherwise consumes more resources and / or provides less cleaning capacity.• Adapt vehicle behavior: In order to temporally separate wet cleaning, disruptive oncoming light and critical driving situations, a short-term deviation from the route ("detour", "swerving", "piroutte") is also possible. In particular in the case of autonomous systems which are flexible in this respect, such as flying drones or small parcel delivery robots, this is a promising strategy.The above strategies may be combined as desired.The cleaning controller may still involve other controlled variables, such as the current amount of precipitation, speeds, start-up information, external cleaning requests (e.g. from the driver via steering column or from a backend), pending cleaning cycles, etc. The cleaning system may act fully automatically or may also involve human control signals.The backlight dependence of the cleaning control can basically be performed at any granularity (obviously limited by the granularity at which the backlight is measured). Thus, for example, the suppression behavior for wet cleaning in the case of back light or the intensity of a drying process can be adapted to the back light continuously or on the basis of one or more threshold values. For example, an angle of incidence or a luminance of a counter light can be used as a controlled variable.The following can also be provided as further embodiments:• Exclusively or in addition to the aforementioned strategies, drivers and / or occupants and / or a backend ("vehicle control center") can also be warned and / or assistance (e.g. maintenance) requested in the case of a strong situation with opposite light. Thus, for example, when a washing process is triggered by the driver in the event of a counterlight, a warning can be issued, which can be overwritten, for example, by a second request.• In a superordinate (partially) autonomous system, the back-light-dependent cleaning may be closely coupled to the system degradation, in order to adequately degrade system functions in the case of critical cleaning situations, for example.In general, it may be advantageous to take account of and minimize back light in global route and time planning. How well this is possible depends on the application and is generally greatly restricted.In summary, in block 44, the cleaning is controlled as a function of the counterlight measure, for example in the case of (current or predicted) counterlight with the following possibilities:• Keep free / dry more intensively (by wiping more quickly, putting more strongly, etc.)• Release at a lower threshold (e.g. remove even light dust layer)• Push-on / push-on Cleaning to Reduce Back Light at Cleaning Time• shorter irrigationIn block 45, the control signals for the cleaning components can be seen in block 46. For this purpose, an interface with a suitable protocol, for example "current on / off", "pulse width modulation PWM," or the like, is usually provided. If necessary, it is also possible to provide an activation into different zones of a zone architecture and a distributed cleaning system.As a result, in block 46, the optical path of the at least one sensor 20 is cleaned, for example by wiping, watering, rotating, brushing, vibrating.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 102019209291A1

[0010]

Claims

Device (80) for cleaning an optical window of an optical sensor (20, 30) for detecting the environment (U) of a motor vehicle (10), wherein optical radiation from the environment (U) of the motor vehicle (10) passes through the optical window, characterized in that the cleaning takes place at least as a function of at least one property (21, 22) of the optical radiation.Device according to Claim 1, characterized in that the optical radiation consists of at least two radiation components, • a first radiation component being generated by scattering photons on objects in the environment of the motor vehicle (indirect radiation component), and • a second radiation component (counter light / direct radiation component) being generated by radiation sources which actively emit optical radiation, and the property of the optical radiation, depending on which the cleaning takes place, being determined by the second radiation component.Device according to one of the preceding claims, characterized in that the cleaning takes place at least as a function of at least one instantaneous and / or one future property of the optical radiation.Device according to one of the preceding claims, characterized in that the cleaning is effected at least as a function of at least one property of the optical radiation in such a way that the start of the cleaning is selected at least as a function of at least one property of the optical radiation.Device according to one of the preceding claims, characterized in that the cleaning takes place at least as a function of at least one property of the optical radiation in such a way that the motor vehicle (10) is controlled in such a way that the property (21, 22, counter light) of the optical radiation is influenced during the cleaning.Device according to Claim 1, characterized in that the cleaning takes place at least as a function of at least one property (21, 22, antilight) of the optical radiation in such a way that • a cleaning which is currently running or imminent is determined and • the motor vehicle (10) is controlled in the sense that a property of the optical radiation which is optimized for the cleaning is achieved during the running or imminent cleaning.Device according to claim 1, characterised in that the cleaning takes place at least depending on at least one property (21, 22, counter light) of the optical radiation in such a way that • the need for cleaning is determined and • at least one time period is determined in which the motor vehicle (10) is positioned in such a way that a property of the optical radiation optimized for the cleaning is achieved, and • the cleaning determined as necessary takes place in the determined time period.Device according to claim 1, characterised in that the cleaning takes place at least depending on at least one property (21, 22, counter light) of the optical radiation in such a way that • the need for cleaning is determined and • the motor vehicle (10) is controlled in such a way that a property of the optical radiation optimized for the cleaning is achieved at least in one time period, and • the cleaning determined as necessary takes place in the determined time period.Device according to claim 1, in particular claim 2, characterised in that the property of the optical radiation, in particular the second radiation portion (counter light), is effected by radiation sources actively emitting optical radiation, by the sensors (20, 30) to be cleaned or by further sensors.Method for cleaning an optical window of an optical sensor (20, 30) for detecting the environment (U) of a motor vehicle (10), wherein optical radiation from the environment (U) of the motor vehicle (10) passes through the optical window, characterized in that the cleaning takes place at least as a function of at least one property (21, 22) of the optical radiation.Method according to claim 10, characterised in that the optical radiation consists of at least two radiation components, wherein • a first radiation component is generated by reflection and / or scattering on objects in the environment of the motor vehicle, and • a second radiation component (21, 22, counter light) is generated by radiation sources actively emitting optical radiation, and the property of the optical radiation, depending on which the cleaning takes place, is determined by the second radiation component.

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