FLOOR MILLING MACHINE WITH CLEANING SYSTEM FOR ONE CAMERA AND METHOD

Description

[0001] The invention relates to a soil milling machine for milling the subsoil, such as a road milling machine, a recycler, or a stabilizer. Furthermore, the invention relates to a method for cleaning a transparent element arranged in a recording area of ​​a camera of a soil milling machine, wherein the soil milling machine is in particular the aforementioned soil milling machine.

[0002] Soil milling machines are typically used in road and path construction, as well as in the construction of squares and plazas. They are usually self-propelled machines with a machine frame supported by wheels and a driver's platform. They include a milling unit with a milling drum mounted in a drum housing, rotating around a central axis, for removing soil material. The milling drum is typically equipped with a variety of tools, such as milling cutters, which are driven into the soil by the drum's rotation, removing it. The removed material is then conveyed to a transport vehicle, such as a truck. In the case of recyclers and stabilizers, the removed material can also be left on site, for example, to create a new road surface or stabilized soil.

[0003] Such soil milling machines typically also have a fluid tank containing a cleaning fluid and / or a compressed air tank. The tank(s) are connected to a piping system through which the fluid and / or compressed air are transported to the machine's intake and discharge points. The cleaning fluid in the fluid tank can be, for example, water. It is known, for instance, to spray the milling unit of the soil milling machine with water during operation, for example, to cool a milling drum, increase the service life of the cutting elements, and / or bind dust. Loose soil material can also be sprayed with water during removal to reduce dust generation. The compressed air tank is typically filled with compressed air by a compressor located on the soil milling machine.Compressed air can be used, for example, to operate tools for maintenance work on the soil milling machine, such as changing milling bits on the milling drum.

[0004] Soil milling machines of this type are typically used on a wide variety of construction sites. They are usually operated from a control platform, which may include a standing area, a seat, and / or controls. This platform can be open or enclosed, for example, as a cabin. Depending on the specific circumstances, an operator's view of various positions in the immediate vicinity of the soil milling machine may be obstructed. Furthermore, the machine itself, or its outer contour, often blocks the operator's direct view of certain areas around the machine. Areas whose visibility would be helpful for precise control of the work process or monitoring of the results are also often not directly visible to the operator in the control platform.It is therefore known to provide at least one camera for capturing image information of the external environment and / or an external view of at least part of the soil tiller. In addition, a control unit is typically provided that receives the image information from the camera and, if necessary, evaluates and / or further processes it. For example, it may include a display unit located in the operator's cab, designed to display the image information, and to which the control unit may forward the image information. The display unit may, for example, be a screen or monitor. The control unit may, for example, be the on-board computer or part of the on-board computer of the soil tiller. Such systems are known, for example, from DE 10 2013 006 464 B4 of the applicant and DE 10 2015 010 500 A1.DE 10 2021 201 942 A1 discloses a machine equipped with multiple cameras. It can be provided that, based on inputs from the machine's built-in components, it determines whether the operating time of the soil-penetrating tool is greater than a reference duration, and that the cleaning system at least partially cleans the camera in response to a determination that the operating time of the soil-penetrating tool is greater than the reference duration. DE 10 2021 201 942 A1 also discloses that, based on camera input, it can determine whether the brightness of one or more images is less than a reference brightness, and that the cleaning system at least partially cleans the camera in response to a determination that the brightness of one or more images is less than the reference brightness.

[0005] During operation, the external environment of soil milling machines of this type is often contaminated, for example, by dust and / or fumes that can accumulate during operation. To protect the camera from these adverse conditions, it typically has a recording area with a transparent element, through which the camera captures the image information. The recording area refers to the area located directly in front of the camera in its line of sight. In particular, camera components may also be located within the recording area, such as the outermost lens or a lens that encloses the camera lens. Furthermore, the recording area may contain a protective cover behind which the camera is located, such as a window in a housing surrounding the camera.For the purposes of this description, the transparent element is defined as the element that separates the camera or the interior of the lens and / or the camera from a potentially contaminated external environment, such as a construction site. The camera therefore looks through the transparent element into the external environment of the machine. The transparent element could thus be, for example, the outermost lens of the objective lens or camera, a protective glass attached to the objective lens or camera, or another protective device or screen located in front of the camera, such as within a housing surrounding the camera. The transparent element considered here therefore protects the camera or the camera lens, in particular the image sensor of a digital camera, from contamination.The transparent element therefore serves as a protective cover for the camera, shielding the camera and its optics from negative influences of the construction site environment.

[0006] During operation of the soil milling machine, dust and / or fumes are frequently present in the machine's vicinity. These also come into contact with the transparent element, causing them to settle and become contaminated. Such deposits and contamination of the transparent element impair the camera's view of the area being recorded. The image captured by the camera, and thus the image information, deteriorates. This can become so severe that the image information is practically useless and no longer provides any assistance. To improve the image quality, the transparent element must then be cleaned, restoring the camera's clear view through it.

[0007] The object of the present invention is to provide an advantageous method for cleaning the transparent element. This method should, in particular, not require any interruption of the operation of the soil milling machine. Furthermore, the cleaning of the transparent element should be carried out regularly and early, so that the image information captured by the camera remains of high quality throughout the entire operation, and cleaning is not delayed until the transparent element is heavily soiled. At the same time, however, for economic and environmental reasons, unnecessary cleaning of the camera or the transparent element should be avoided whenever possible, or should only be carried out when it is likely or actually necessary.

[0008] The problem is solved using a soil milling machine or a method according to the independent claims. Preferred embodiments are specified in the dependent claims.

[0009] A soil milling machine of this type includes a cleaning outlet connected to the piping system via a valve and / or a fluid supply system controlled by the control unit. This outlet is designed to supply the transparent element with fluid from the fluid tank and / or compressed air from the compressed air tank for cleaning. The control unit is configured to initiate cleaning of the transparent element depending on the operating situation and / or image information. This image information includes, for example, an image captured by the camera or the data that defines an image, for example, in digital form. It therefore refers specifically to image information from a picture currently being captured by the camera.In this context, the control unit initiating cleaning of the transparent element means that it actuates one or more valves and / or the fluid delivery system, in particular a pump, such that cleaning fluid reaches the cleaning outlet and the transparent element is exposed to fluid, such as water and / or compressed air, via the cleaning outlet. Alternatively or additionally, initiating cleaning by the control unit can also mean that the control unit informs the operator that cleaning is necessary, whereupon the operator starts the cleaning process by entering a control command. This information regarding the need for cleaning is displayed, for example, via the display device described in more detail below.Alternatively, a warning light or an acoustic signal can be provided to indicate the need for cleaning to the operator. The transparent element is cleaned by spraying or nozzle it with the fluid, in particular a liquid fluid such as water and / or a gaseous fluid such as compressed air. The cleaning outlet is preferably a device through which the cleaning fluid can be applied from the piping system to the transparent element in a targeted manner. For example, the cleaning outlet is a cleaning nozzle. By nozzleing the transparent element with cleaning fluid, it is freed from contaminants, thus improving the image information or the camera's view through the transparent element.In principle, the control unit can perform cleaning of the transparent element when an operator enters a corresponding control command, for example, after the control unit has indicated to the operator that cleaning is necessary. However, it is advantageous if the control unit performs cleaning automatically. For this purpose, the control unit uses the operating status of the soil milling machine and / or the image information supplied by the camera itself, analyzes it, and decides based on the result whether or not cleaning is carried out, as explained in more detail below. The transparent element comprises, in particular, a glass, preferably anti-reflective glass, for example, a glass with the trade name Conturan (brand name of Schott AG).

[0010] In order for the control unit to initiate cleaning based on a work situation, it is advantageous if the control unit is designed to recognize various operating states of the soil tiller and, for example, record their presence, absence, and / or duration, using this information as a basis for deciding whether or not to initiate cleaning. The work situation considered by the control unit includes, for example, switching the soil tiller on or off. For instance, the control unit can initiate cleaning at the beginning and / or end of machine operation, particularly at each start and / or end of operation.The start and / or end of machine operation can be defined, for example, by the operation of a combustion or electric motor (e.g., electric drive motors) and / or by the operation of the control unit. Furthermore, the operating situation can include the start or end of a work operation and / or a transport operation. A work operation, for example, describes the operation of the soil tiller in which the tilling unit is used for soil cultivation, specifically for milling the subsoil. It can therefore be, in particular, a tilling operation and thus be characterized, in particular, by the operation, especially rotation, of the tilling drum. A transport operation, on the other hand, describes, for example, the operation of the soil tiller in which the tilling unit is not used for soil cultivation, in particular when the tilling drum is stationary relative to the machine frame.During transport, the soil milling machine is moved within or between construction sites, for example, using its own transport equipment. Here, too, it is preferable for the control unit to initiate cleaning at the beginning and / or end of each work and / or transport operation. On soil milling machines, the milling drum is typically height-adjustable, allowing for different milling depths. The work situation may also involve lowering or raising the milling drum. In this case, the control unit can therefore initiate cleaning whenever the height of the milling drum or the milling depth of the soil milling machine is changed.

[0011] Furthermore, a time-controlled cleaning process, particularly using a timer or timer function that monitors time intervals, can be implemented as an additional or alternative measure. The work situation can then, for example, encompass the expiration of a time interval, such as the operation or working cycle of the soil milling machine. The operation of the soil milling machine is defined, for instance, as the time interval between switching the machine on and off. The working cycle is defined as previously explained. Alternatively or additionally to a time interval, a distance traveled can also be used, so that the work situation includes the completion of a certain distance, for example, in relation to the previously described operation or working cycle of the soil milling machine.Both the timer function, the monitoring of a time interval, and the monitoring of a distance can be implemented for any of the operating situations described herein. The timer function can be performed by the control unit, which is appropriately designed and, for example, includes a suitable computer program.

[0012] The work situation can also additionally or alternatively include reaching a threshold value. This could, for example, be a threshold value for the weight or volume of soil material overloaded onto a transport vehicle by the soil milling machine. The soil milling machine may, for instance, have a loading assistant or loading assistance system that monitors the loading of the transport vehicles. This system can determine the overloaded weight or volume of soil material. If a threshold value for weight or volume of soil material is exceeded, the control unit can initiate cleaning. Additionally or alternatively, the threshold value could also be the threshold of a counter, such as a counter for the number of machine starts or the number of transport vehicles loaded by the soil milling machine.In this case, a counter is provided that records, for example, the number of machine starts and / or the number of transport vehicles loaded by the rotary tiller. If the counter exceeds the threshold, the control unit initiates a cleaning cycle. Such a counter can, in principle, be used for any work situation described herein that does not involve continuous operation of the rotary tiller but rather time-limited processes, such as the start and end of work, lowering or raising the tilling drum, etc. The specific thresholds, i.e., their numerical values, can be fixed. In a preferred embodiment, the thresholds are dynamically adjusted.For this purpose, the control unit records, for example, how often an operator manually initiates cleaning of the transparent element by issuing a corresponding control command, without the control unit having previously indicated that cleaning is necessary. Depending on the frequency of these manual cleanings, the control unit can adjust the threshold value. This is done, for example, by lowering the threshold values ​​if the operator regularly initiates manual cleaning, such as 1, 2, 3, or 4 times per hour. Conversely, if the operator never or rarely initiates manual cleaning, the threshold values ​​can be raised to prevent unnecessary cleaning.

[0013] Finally, it can also be additionally or alternatively stipulated that the work situation includes the start or end of operation and / or the type of operation of a water spray system for moistening the milling unit and / or the removed soil material. Soil milling machines of this type can include water spray systems, for example, to spray roller drums or milling drums or removed soil material with water. Spraying the milling drum cools it and extends the service life of the chisels used. The switching on and / or off of such a water spray system can now be used as a work situation that is taken into account by the control unit to initiate cleaning of the transparent element. In particular, the control unit is preferably also designed to control the operation of the water spray system. The duration of the water spray system's operation can also be taken into account.The operating mode of the water spray system, in this context, refers to factors such as the water spray system's flow rate, the current use of available water nozzles, and which systems of the rotary tiller are currently being sprayed with water. All these factors can be taken into account by the control unit, resulting in the cleaning of the transparent element at regular intervals. This reliably prevents excessive soiling of the transparent element and the associated degradation of the camera's image information. Conversely, it avoids unnecessary cleaning of the transparent element, which would involve higher material consumption and consequently higher costs.It is also possible for the water spray system and the cleaning outlet to be supplied with the same fluid, for example water, from the same tank, for example the fluid tank. The fluid is thus used, for example, for both cleaning the camera and cooling the milling drum, with only one shared tank for the fluid serving both applications.

[0014] Additionally or alternatively, the control unit can also initiate cleaning of the transparent element based on the image information. Preferably, the control unit is designed to evaluate the image information as part of a dirt detection process and initiate cleaning of the transparent element when the dirt detection system detects contamination. Contamination of the transparent element alters the image information captured by the camera. Accordingly, contamination of the transparent element can be deduced from the image information or from the changes in the image information. In this process, the contamination is inferred solely from the image information provided by the camera.For this purpose, the control unit can, for example, record parameters of the image information, as explained in more detail below, and store them in memory for a certain period of time. In this way, changes in the parameters over time can be detected, which can be used as an indication of contamination of the transparent element.

[0015] Various image data parameters commonly used in image processing can be employed as parameters. For example, it is preferred that the control unit be designed to use parameters such as brightness, contrast, saturation, sharpness, relative luminescence, and / or pattern recognition in a portion or all of the image data for dirt detection. These parameters can be directly read or determined from the image data or a portion thereof. "A portion of the image data" means, for example, that different areas of the image can be considered.For example, the image can be divided into quadrants, specifically four equally sized rectangular sections, or concentric areas can be used, such as a peripheral area and one or more central areas surrounded by the peripheral area. Naturally, the entire image can also be considered. Relative luminescence can take into account the RGB composition—that is, the proportion of red, green, and blue light—of individual pixels in the image information. Pattern recognition is based on the understanding that contamination of the transparent element can have characteristic effects on the image information. For example, different areas of the image may have different brightness levels when contaminated, even though they would have the same brightness if the transparent element were clean.An example of such pattern recognition would be if the control unit detects that the edge of the image information, i.e., the outer edge of an image, is significantly darker than the center. Additionally or alternatively, and particularly through an image comparison described in more detail below, it can be determined whether areas darken continuously over time, which ultimately indicates an increasing degree of soiling. It is also possible to check the available image information, again particularly through the image comparison described in more detail below, for patterns that do not change over time or during the ongoing work process.In this way, image information originating from objects beyond the transparent element, which therefore change over time during the work process (such as the external environment and / or the ground surface), can be distinguished from image information originating from dust particles adhering to the transparent element, which therefore do not change or change differently over time during the work process. This allows for an assessment of whether a dust particle is adhering to the transparent element and / or whether a level of soiling requiring cleaning has been reached. Such patterns can be used for dirt detection. It may be possible to define one or more limit or threshold values ​​for one or more of the parameters used for dirt detection; exceeding or falling below these values ​​then indicates a state of soiling requiring cleaning.If, based on the aforementioned parameters, it is determined that the transparent element is contaminated or that cleaning of the transparent element is advisable and / or necessary, the control unit initiates a cleaning process.

[0016] A particular focus of the control unit's evaluation of image information is preferably on changes in that information. It is therefore preferably designed that the control unit is configured to detect temporal changes in the image information and to recognize contamination of the transparent element when these changes exceed a threshold. For example, contamination can be detected if the aforementioned parameters—brightness, contrast, saturation, sharpness, and / or pattern—in the current image information deviate from previous values, especially when the transparent element is clean.In image processing, it is common practice to capture such parameters numerically, making it relatively easy to define a threshold for permissible changes. Exceeding this threshold triggers the control unit to infer contamination and initiate cleaning. For example, the control unit can use image information to determine that the brightness of the image, either partially or overall, has decreased by a certain percentage. The control unit can, of course, compensate for the influence of external lighting conditions. The percentage used as the threshold can range from >0% to 100%, preferably 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%.If the detected change in the parameter under consideration, for example, brightness, exceeds this threshold, the control unit concludes that the element is dirty and initiates cleaning. Additionally or alternatively, the control unit can also evaluate whether the image information changes over time in parts of the image or image data, detecting dirt on the transparent element if the changes fall below a certain threshold. For example, if the transparent element were so heavily soiled that no light could pass through it at all, the image captured by the camera, or the image data it contains, would not change over time but would remain constant.This effect becomes noticeable with less contaminated transparent elements because the aforementioned image parameters change less dramatically over time than with clean transparent elements. Therefore, the control unit can be configured to evaluate the temporal changes in the image information and detect contamination when these changes fall below a certain threshold. This threshold can also be specified as a percentage. If the image parameters no longer change over time as they would for a clean transparent element, contamination is present. The threshold could, for example, be 95%, 90%, 85%, 80%, 75%, 70%, 65%, 60%, 55%, or 50% of the temporal changes of the respective parameter observed with a clean transparent element.If less significant changes occur over time, the control unit initiates a cleaning of the transparent element due to contamination. To determine changes in the image information, or at least a portion thereof, over time, a current image can be compared with one or more older images, for example, at intervals of one or more minutes. This process can be repeated regularly, particularly throughout the work process. For this comparison, one or more of the parameters mentioned in the previous paragraph can be used. It is preferred that the reference image is taken at machine start-up, at the beginning of work, and / or after a cleaning process. Additionally or alternatively, a new reference image can be taken after each successive cleaning process.

[0017] Due to the known operating procedure of the soil milling machine, it may be possible to predict in advance, particularly with regard to certain parameters, what image information to expect or within what range parameters can and should lie, especially with a sufficiently clean transparent element. Accordingly, the control unit can be programmed via software to anticipate the expected image information, so that contamination is detected when the image information captured by the camera deviates from the expected image information, for example, beyond the threshold values ​​mentioned above. However, it is particularly helpful if a reference is also positioned within the camera's field of view, the appearance of which is also known, so that changes in the appearance of the reference indicate contamination of the transparent element.In a preferred embodiment, the control device is therefore configured to use a reference detected by the camera, such as a light source, a contour of the machine, or a pattern arranged, in particular, within the camera's field of view on the machine or on the transparent element itself, for dirt detection. The reference is arranged in a known relative position to the camera, so that it is known in which part of the image information the reference is located. The reference can be a permanent reference, for example, a contour or pattern in the camera's field of view, which is always present and should therefore always appear the same in the image information. This could, for example, be parts of the soil milling machine or outlines of parts of the soil milling machine.Alternatively, the reference can also be a temporary reference, for example, a light source that is only switched on intermittently. Since the effect of switching on the light source on the image information is known when the transparent element is clean, a correspondingly different or reduced change in the image information can be interpreted as an indication of contamination of the transparent element. This, too, can be quantified according to the percentage values ​​already specified above. Furthermore, the light source can be of different colors. For example, the light source can emit light of a specific color, such as white, green, red, blue, or yellow light. Preferably, the light source emits light of a color that differs from other light sources on the milling machine and / or on the construction site, and in particular from daylight.In this way, the change in image information due to the switching on of the light source can be clearly attributed to the light source.

[0018] It is also possible, either additionally or alternatively, to temporarily project a reference image or structure into the camera's field of view, for example onto the floor and / or onto a part of the machine, using a suitable projection device such as a laser or a spotlight. This can be done temporarily or at specific times, for example, depending on the situation (machine start, milling start, manual triggering, etc.) and / or after defined time intervals. This reference image or structure can be a defined structure, such as a pattern like a grid, a shape, or similar, including a company logo, etc. This reference image or structure must be defined with respect to certain parameters, such as size, shape, brightness, etc.The projection is always the same, so that deviations caused by contamination of the transparent element are particularly easy and precise to identify in the recorded image, both quantitatively and qualitatively. Here, too, it can be configured that the projection is permanently activated, only in certain work situations (e.g., during milling), only at specific time intervals, or only in specific situations (e.g., after a cleaning process). Furthermore, when the projection device is activated, a reference image can be captured at specific times (e.g., at the beginning of a work process, after a cleaning process, etc.).It may also be provided that the activation of the projection device and / or the recording of a reference image is temporally coupled with the triggering of a cleaning process, such that the projection device is only activated after cleaning and the reference image is then recorded.

[0019] It goes without saying that a suitable control unit can be provided to manage the aforementioned processes. This unit can be connected to appropriate sensors to obtain the information relevant for triggering and / or executing the control processes. As already explained, the entire image or only parts of the image or image information can be used for evaluation by the control unit. In addition to the qualitative changes to the image information or parts thereof mentioned above, a quantitative evaluation can also be performed to determine how many parts or to what extent changes have occurred within the image information or image.It is therefore preferably provided that the control device is designed to detect changes in parts of the image information, for example, individual pixels, and to detect contamination of the transparent element when the proportion of altered image information exceeds a threshold. For example, as described above, the control device evaluates various areas of the image or various parts of the image information, for example, each individual pixel, to determine whether it exhibits changes, such as temporal changes. If the proportion of the considered areas with altered image information reaches or exceeds the threshold, contamination is inferred.For example, contamination is inferred if the proportion of areas with altered image information, such as the proportion of pixels in the image, reaches 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50% of the total area considered, such as pixels. In this case, the control unit can initiate cleaning of the transparent element.

[0020] Overall, the changes in image information caused by contamination of the transparent element are diverse and sometimes manifest as only slight alterations in one or more parameters simultaneously. It can therefore be difficult to identify one or a few parameters that can be used to infer contamination. It can thus be advantageous to employ software capable of evaluating the multitude of individual, often subtle, changes, or at least considering two or more parameters. Preferably, the control unit is designed to evaluate the image information for contamination detection using machine learning-based software.The software was preferably trained beforehand with a large amount of image information, each assigned to a clean transparent element or a dirty transparent element, particularly one dirty to varying degrees. This allows a multitude of parameters to be included in the analysis simultaneously, enabling the software to determine whether a transparent element is dirty or not based on an overall impression of the image information. Additionally or alternatively, the software can also be configured to observe operator behavior and, for example, determine under which conditions and / or when changes occur that the operator manually triggers a cleaning process during the ongoing workflow.

[0021] In principle, for the purposes of the present invention, it is sufficient if the soil milling machine comprises exactly one camera. However, it is preferred if it comprises at least one and, in particular, a plurality of cameras. In this case, all the features described above apply to the at least one camera and, preferably, to all cameras. In particular, a corresponding cleaning outlet can be provided for each camera, through which the transparent element of this camera can be cleaned by the control unit as described. The camera(s) can, in principle, be arranged at any point on the soil milling machine and can record any areas of interest for the operation of the soil milling machine.Areas that are difficult to see are particularly advantageous, for example, areas in the working direction of the soil milling machine directly in front of, behind, or perpendicular to the working direction of the soil milling machine, next to the milling unit. The area around the milling unit is typically where most of the dust and / or fumes are generated during operation of the soil milling machine, resulting in particularly heavy soiling of the transparent element in this area. Therefore, such a camera with a cleaning device can be positioned, in particular, on the underside of the soil milling machine, in front of or behind the milling unit when viewed in the milling direction.In a preferred embodiment, the soil milling machine additionally or alternatively comprises a transfer conveyor and a loading conveyor, wherein the transfer conveyor is designed to transport milled soil material from the milling drum housing to the loading conveyor, and the loading conveyor is designed to transport the milled soil material onto a transport vehicle. It has been found that, in particular, a camera arrangement on the loading conveyor, for example with a viewing area at the material discharge point or a viewing direction towards the discharged milled material and the transport vehicle, provides the operator with a particularly advantageous view of the loading process. Further advantageous areas that can be viewed with a camera include the area in front of the soil milling machine, especially below the loading conveyor, in the working direction of the soil milling machine in front of and behind the milling drum, the transfer area between the transfer and loading conveyors, etc.A camera pointed at one of these areas can become dirty relatively quickly, so equipping one or more of these cameras with a cleaning device as described above is particularly advantageous. It may also be provided that only one or a subset of the cameras on the soil milling machine have such a cleaning device. In particular, cameras whose image data is used for automated and / or semi-automated processes and / or which are positioned in locations that are difficult to access from outside the machine are equipped accordingly.

[0022] Preferably, the soil milling machine includes a conveying device, such as a pump, connected to the piping system for transporting fluid from the fluid tank. This could be, for example, a water pump if the fluid is water. The pump is specifically designed to build up fluid pressure in the piping system, which can be used, for example, to supply the transparent element with fluid via the cleaning outlet. If the soil milling machine has a water spray system, the pump can be the same pump that also supplies the water spray system. In other words, one and the same pump can be used for both the water spray system and supplying the transparent element with fluid from the fluid tank. Furthermore, the soil milling machine can include a compressor that fills the compressed air tank with compressed air.Such compressors are typically already present on soil milling machines of this type. If the soil milling machine has several cameras, it is preferably provided that each camera has a cleaning outlet, with each cleaning outlet having its own pump that supplies fluid to it, or with one pump designed to supply all cleaning outlets with fluid. Furthermore, separate cleaning outlets for fluid and compressed air may be provided.

[0023] To prevent the cleaning of the transparent element from being hindered at low temperatures, the cleaning outlet(s), preferably all cleaning outlets, and / or the fluid tank and / or the piping system and / or the valve can be heated. For this purpose, an electric heater or warm exhaust air from an internal combustion engine can be used, for example. Additionally or alternatively, a drain can be provided through which the fluid tank and / or the piping system can be emptied, particularly completely. This can be done purely by gravity or driven by the fluid conveying device or the pump. A suitable outlet for emptying the piping system can be provided. This is helpful to prevent liquids from freezing in the respective components during extended periods of inactivity at cold temperatures.A corresponding emptying process can also be initiated by the control unit, particularly after the operator has entered a control command.

[0024] As already mentioned, the cleaning fluid can be water. In a preferred embodiment, the cleaning fluid can be provided with an additive, in particular a cleaning agent. The additive can either be already mixed with the fluid in the fluid tank or it can be located in a separate additive tank and mixed with the fluid in the fluid tank outside the fluid tank, but preferably within the piping system. The additive can be a solid or a liquid. Examples include surfactants, alcohols, or similar substances. In the case of a liquid, it can be provided in a separate additive tank and mixed with the fluid from the fluid tank in a constant ratio, for example, via a gear, piston, diaphragm, or water jet pump.By using a water jet pump to supply the additive, the single pump described above remains sufficient for the fluid. The other pumps can be controlled separately, allowing the mixing ratio to be adjusted as desired. The cleaning effect can be enhanced by using an additive. Furthermore, the system can be configured so that the operator can specify whether or not the additive should be used during the current operation. The control unit is therefore designed to disconnect or connect the additive tank to the piping system, for example, via a valve. This allows the operator to select whether or not an additive contained in the tank should be used.

[0025] The transparent element can therefore be cleaned either with the fluid, with a mixture of the fluid and an additive, or with compressed air, or with a mixture of the fluid, optionally with an additive and compressed air. To mix these different components as homogeneously as possible, a mixing device for mixing the fluid with the compressed air and / or the additive, in particular a static mixer, is preferably provided. Unlike a simple pipe section, a static mixer has additional elements built into the pipe that influence the flow through the static mixer and thus result in mixing. Such static mixers are known to those skilled in the art, so they do not need to be described in more detail here. The mixing device is preferably arranged in the pipe system and, in particular, directly upstream of the cleaning outlet.In this way, a homogeneous mixing of the aforementioned components can take place, which contributes to thorough cleaning.

[0026] To prevent contamination or clogging of the cleaning outlet, suitable filters can be installed in the piping system, especially in the piping system behind the fluid tank and / or the compressed air tank.

[0027] The control unit can, in principle, use any combination and / or sequence of fluid, in particular water and / or compressed air, with or without additives, to actuate the transparent element. For example, the control unit can be configured to simultaneously actuate the transparent element with a liquid fluid from the fluid tank and with compressed air from the compressed air tank for cleaning. Additionally or alternatively, the control unit can be configured to first actuate the transparent element with a liquid fluid from the fluid tank and then with compressed air from the compressed air tank for cleaning. In this way, the liquid fluid is also removed from the transparent element by the compressed air, so that no residual fluid on the transparent element alters the image information.In particular, it may be provided that a reference image, as described above, is captured. The control device can be configured to actuate the valve in such a way that the transparent element is supplied with a continuous or pulsed flow of liquid fluid and / or compressed air from the fluid tank and / or the compressed air tank for cleaning. Furthermore, a temporal sequence of any selection and combination of all the aforementioned supplies can be provided, for example, first a pulsed supply of liquid fluid from the fluid tank followed by a continuous supply of compressed air or similar.

[0028] To ensure that the cleaning of the transparent element is successful, the invention provides that the control unit is designed to perform a renewed dirt detection after cleaning and initiate another cleaning of the transparent element if contamination is still detected. In this way, the cleaning process is repeated until the desired result is achieved. For this purpose, an original reference image or one created before the start of cleaning can be used. Alternatively, it can be provided that the process is aborted after a certain number of unsuccessful cleaning attempts, for example, 3, 4, or 5, and a warning message is displayed to the operator. This message can also be displayed on the display device.In this case, either a defect must be assumed or the contamination of the transparent element cannot be removed by the cleaning system of the invention, so that cleaning by an operator is required.

[0029] Furthermore, one or more sensors, even different ones, can be provided and connected to the control unit to detect various states of the overall system and provide their results to the control unit. For example, the control unit may include a level sensor on the fluid tank and / or a pressure sensor on the compressed air tank and / or a temperature sensor at the cleaning outlet and / or on the fluid tank and / or on the valve and / or on the pump and / or in the piping system. In other words, the control unit is connected to such sensors. It is specifically designed to monitor the sensor signals. It can also display the states determined by the sensors, or the sensor signals themselves, on the display unit to inform the operator.For example, warning signals can be generated in this way if the fluid tank level and / or the compressed air tank pressure falls below a threshold. A warning can also be displayed to the operator if a component freezes, preventing the transparent element from being supplied with fluid or compressed air. In particular, the sensor signal from the temperature sensor(s) can also be used to control a heating device that heats and, in particular, defrosts the relevant components.

[0030] In cases where the soil milling machine has multiple cameras, the control system can be configured to initiate cleaning of the transparent element of each camera individually and independently of the others, for example, if the image information from that camera detects contamination of the transparent element. Furthermore, the system can allow the operator to input a specific control command to perform cleaning on a particular camera. Alternatively, the cameras can be grouped together. For example, if several cameras are located in a functionally related area of ​​the machine, such as in or under the loading conveyor belt, it can be assumed that these cameras are also exposed to similar types of contamination.Therefore, if the transparent element of one camera in this group is found to be dirty, it can be advantageous to initiate cleaning of the entire group. Alternatively, it may be possible to clean all cameras simultaneously. Overall, the control unit is preferably designed to initiate cleaning of a single camera, several cameras, or all cameras of the soil milling machine at the same time. This allows for a desired focus: either on proactively maintaining the highest possible cleanliness of the cameras' transparent elements or on targeted cleaning to conserve resources.

[0031] It is particularly preferred, in the case that the soil milling machine has more than one camera, in particular at least three or more cameras, each with a cleaning device, that a master camera is defined with regard to the cleaning process and its triggering, and that the other cameras are classified as slave cameras with regard to the cleaning function. This means that, when cleaning is performed based on image information, only the image information of the master camera is considered. If it is determined for this camera or its image information that cleaning should be triggered, for example by exceeding a threshold and / or via alternative methods as described above, this is also assumed to apply to all slave cameras simultaneously, so that they are then also cleaned.This advanced training therefore requires the evaluation of image data from only one camera, while simultaneously achieving the cleaning of all cameras as described above. The master camera is preferably mounted on the rest of the soil milling machine, particularly near the milling unit or near the discharge point of the transport device, as described above.

[0032] Finally, internal or external factors may influence how well contaminants detach from the transparent element. Internal factors could include, for example, the presence, use, or absence of an additive for the cleaning fluid. External factors could include, for example, the weather or the composition of the soil being treated. The control device can react to these factors, as previously described, by, for example, switching between continuous or pulsed application of the transparent element. Furthermore, the control device is preferably configured to actuate the pump and / or the valve to adjust the flow rate of the cleaning outlet. In other words, the control device is designed to adapt the flow rate of the cleaning outlet to the prevailing conditions.If, for example, after cleaning the transparent element is found to be still dirty, the control device reacts accordingly by increasing the flow volume of the cleaning outlet during the subsequent cleaning, thus intensifying the cleaning process. Conversely, if, for example, the operator enters a control command that activates the addition of an additive to the cleaning fluid, the control device can reduce the flow rate of the cleaning outlet, since the cleaning is already improved by the use of the additive, resulting in overall fluid savings.

[0033] The problem mentioned at the outset can also be solved by a method for cleaning a transparent element arranged in the recording area of ​​a camera of a soil milling machine, in particular a soil milling machine according to the preceding descriptions. Accordingly, all explanations already given above regarding the features, effects, and advantages of the soil milling machine, especially regarding process steps, apply equally, by analogy, to the method according to the invention, and vice versa. Reference is made to the other descriptions only to avoid repetition.Specifically, the method according to the invention comprises at least the following steps: monitoring the contamination of the transparent element of the camera, detecting contamination of the transparent element depending on the operating situation of the soil milling machine or depending on image information acquired by the camera, and supplying the transparent element with liquid fluid and / or compressed air from a fluid tank and / or a compressed air tank. Monitoring the contamination is carried out in particular by monitoring the operating situation of the soil milling machine and / or the image information, as described above. In particular, the control unit can be designed to carry out the method according to the invention. This means that the control unit receives and evaluates the necessary control commands or data and controls the corresponding components of the soil milling machine.For example, the control unit is equipped with appropriate software.

[0034] The method according to the invention may be provided in such a way that the detection of contamination of the transparent element, depending on image information recorded by the camera, is carried out solely on the basis of a master camera, while the triggering of cleaning or the application of liquid fluid and / or compressed air to the transparent element from a fluid tank and / or a compressed air tank is carried out on the basis of this for the master camera and at least one or more slave cameras.

[0035] The invention is explained in more detail below with reference to the embodiments shown in the figures. The figures schematically show: Figure 1: a side view of a soil milling machine; Figure 2: a first embodiment of a system for cleaning a transparent element of a camera; Figure 3: a second embodiment of a system for cleaning a transparent element of a camera; Figure 4: a third embodiment of a system for cleaning a transparent element of a camera; Figure 5: a fourth embodiment of a system for cleaning a transparent element of a camera; Figure 6: a fifth embodiment of a system for cleaning a transparent element of a camera; Figure 7: a flowchart of the method; and Figure 8: a camera with a recording area and a transparent element arranged in the recording area.

[0036] Identical or similarly functioning components are numbered with the same reference numerals. Repeating components are not individually labeled in each figure.

[0037] The Figure 1Figure 1 shows an example of a soil milling machine 1 according to the invention, specifically a road milling machine, here a cold milling machine of the mid-rotor type, also called a "large milling machine". The soil milling machine 1 preferably has a machine frame 3 with a driver's platform 2. The driver's platform 2 preferably contains operating elements with which an operator controls the soil milling machine 1. The soil milling machine 1 preferably includes a drive motor 4, which can be, for example, an internal combustion engine, in particular a diesel engine, or one or more electric motors. During operation, the soil milling machine 1 preferably moves in the working direction a over a surface 8 and processes it.

[0038] For this purpose, the soil milling machine 1, designed as a road milling machine, has according to Figure 1Preferably, the machine includes drive mechanisms 6, in the example shown, tracked tracks, and, in particular, a milling drum 9 as a soil cultivation device. The milling drum 9 is preferably mounted rotatably in a milling drum housing 7 about a rotation axis 10 oriented transversely to the working direction a. The milling drum 9 and the milling drum housing 7 form a milling device. During operation, the milling drum 9 preferably removes soil material from the ground 8. From the milling drum housing 7, this removed soil material is preferably conveyed onto a transfer conveyor belt 11, from which it is transported forward in the working direction a to a loading conveyor belt 5. The loading conveyor belt 5 then preferably transfers the removed soil material onto a transport vehicle (not shown) for removal.

[0039] The soil milling machine 1 shown also preferably has a water spray system 28. In the case of the soil milling machine 1 according to Figure 1The water spray system 28 is preferably designed to spray the interior of the milling drum housing 7, in particular the milling drum 9, and / or the milled soil material on the transfer conveyor belt 11 and / or on the loading conveyor belt 5 with water. This serves both to cool the milling drum 9 and to prevent dust. The water spray system 28 is connected in particular to the piping system and the associated pump and water tank, which will be described later. In particular, the water spray system 28 is also supplied by these components.

[0040] The soil milling machine 1 comprises at least one and preferably a plurality of cameras 12. The cameras 12 can, in principle, be arranged at any position on the soil milling machine 1. They are preferably designed to record the external environment of the soil milling machine 1 and / or an external view of at least parts of the soil milling machine 1, or image information about these. For example, cameras 12 are provided that record the soil 8 directly in front of and / or directly behind the soil milling machine 1 and / or a milling unit. In the soil milling machine 1 according to Figure 1Furthermore, a camera 12 can be provided on the loading conveyor belt 5 to monitor the transfer process to the transport vehicle. All cameras 12 are preferably connected to a control unit 20, which can be part of the on-board computer of the soil milling machine 1 or be the on-board computer itself. The control unit 20 preferably receives the signals from the cameras 12 and can, in particular, also process and / or evaluate them. It is also preferred that the control unit 20 is connected to a display unit 24, for example, a display or screen in the operator's cab 2, via which the control unit 20 can display information to the operator of the soil milling machine 1.For example, the control unit 20 can display the image information from the cameras 12 on the display unit 24, allowing the operator to use the corresponding views for easier operation of the soil milling machine 1 or for more precise control. Finally, the control unit 20 preferably also includes a counter 27 with which the control unit 20 can count various parameters relating to the operating status of the soil milling machine 1. For example, the counter 27 can be configured to count the number of machine starts or the number of transport vehicles loaded by the soil milling machine 1. The corresponding values ​​can be used by the control unit 20 to indirectly infer the quality of the image information provided by the cameras 12, thus reflecting the operating status of the soil milling machine 1.Additionally, the counter 27 can also be configured as a timer if time intervals are to be determined.

[0041] In Figure 8 A camera 12 is shown in more detail as an example for all cameras 12. The cameras 12 preferably comprise a recording area 13. The recording area 13 denotes at least a part of the space through which the camera 12 records images or image information. Preferably, at least one transparent element 37 is located in the recording area 13, which is, for example, the outermost lens or a transparent protective cover for the lens of the camera 12 (in Figure 8 (example shown on the right in recording area 13) or a viewing window in a housing protecting the camera 12 (in Figure 8(for example, the transparent element 37 is shown on the left in recording area 13). Preferably, the transparent element 37 in this case is the transparent element in recording area 13 that shields the camera 12 from the outside environment, such that dust and / or vapors present in the outside environment can come into contact with the transparent element 37, but not with parts of the camera 12 located behind the transparent element 37. During operation of the soil milling machine 1, it can therefore happen that dust and / or vapors from the construction site settle on the transparent element 37 and cloud it. This leads to a progressive deterioration of the image or image information recorded by the camera 12.This problem is particularly pronounced at positions on the soil milling machine 1 where a large amount of dust is expected during operation, for example, under, or preferably directly under, the transfer conveyor belt 11. Here, the image information for the control unit 20 or the operator can very quickly become useless.

[0042] To counteract this deterioration of the image information, a system for monitoring the contamination of the transparent element 37 of the cameras 12 and cleaning of the transparent element 37 of at least the camera 12 in which contamination of the transparent element 37 is detected is preferably provided. Such systems are exemplified in the Figures 2-6shown. They all include at least one fluid tank 14, for example a water tank, and / or a compressed air tank 15. Furthermore, a piping system 19 and, in particular, a pump 21 are preferably provided. The pump 21 is preferably designed to pump the fluid from the fluid tank 14. In particular, the pump 21 also supplies the optional water spray system 28 of the soil milling machine 1 with fluid from the fluid tank 14. A filter 16, for example a water filter, can be provided in the piping system 19 downstream of the fluid tank 14 to prevent clogging of other components by contaminants that may be present in the fluid tank 14. For the same purpose, an air filter 17 is optionally located in the piping system 19 downstream of the compressed air tank 15. The filter 16 and the air filter 17 are included in all embodiments of the Figures 2-6The systems shown include at least one cleaning outlet 22, for example, a cleaning nozzle. The cleaning outlet 22 is designed to supply the transparent element 37, located in the recording area 13 of the camera 12, with fluid from the fluid tank 14 and / or compressed air from the compressed air tank 15. For this purpose, the cleaning outlet 22 is connected to the respective tanks via the piping system 19. Fluid from the fluid tank 14 is pumped to the cleaning outlet 22, in particular by the pump 21. Compressed air from the compressed air tank 15 does not need to be pumped, as the compressed air tank 15 is filled with compressed air, in particular by a compressor (not shown). Preferably, at least one valve 18 is provided, via which the control device 20 can control the flow of fluid and / or compressed air to the cleaning outlet 22.In particular, the valve 18 or the valves 18 are also designed so that the control device 20 can adjust the flow volume as desired.

[0043] The following section addresses the specific features of the exemplary embodiments of the Figures 2-6 The following descriptions are included. These differ from one another in certain aspects, while many of the features of the embodiments are identical. The focus of the following description is therefore on the differences between the individual embodiments. Features not explicitly mentioned in the embodiments may be present in the embodiments just as in the other embodiments described. The respective distinguishing features may also be used in embodiments other than those specifically shown. All of the features mentioned below can be combined with one another as long as they are not mutually exclusive.

[0044] In the exemplary embodiment according to Figure 2 Separate piping systems 19, cleaning outlets 22, and valves 18 are provided for the fluid from fluid tank 14 and the compressed air from compressed air tank 15. The control unit 20 preferably controls both the pump 21 for conveying the fluid and all valves 18. In this way, the flow of fluid and compressed air is regulated separately and independently of each other. The transparent element 37 of the camera 12 is therefore supplied with cleaning fluid and compressed air separately via separate cleaning outlets 22.

[0045] In Figure 3An embodiment is shown in which fluid from the fluid tank 14 and compressed air from the compressed air tank 15 can be applied together to the transparent element 37 of the camera 12 for cleaning via a common cleaning outlet 22. For this purpose, the line system 19 coming from the tanks is combined in a valve 18, which has corresponding switching positions to direct either fluid or compressed air, or both fluid and compressed air, to the cleaning outlet 22. This valve 18, like the pump 21, is preferably controlled by the control unit 20. In particular, a single line of the line system 19 is arranged downstream of the valve 18, which, in a corresponding switching position of the valve 18, conveys both fluid and compressed air.To ensure the most homogeneous mixing of fluid and compressed air possible, a mixing device 23 can be provided at this point, upstream of the cleaning outlet 22. The mixing device 23 is, for example, designed as a static mixer. Static mixers comprise a pipe section in which additional internal components are provided that influence the flow and lead to a homogeneous mixing of the transported fluids. However, the mixing device 23 can also be omitted. Furthermore, the mixing device 23 can also be used in the other embodiments in which the fluid and the compressed air (and optionally an additive) are to be mixed, especially in the embodiments shown. Figures 5 , 6 and 7. From the single, common cleaning outlet 22, the mixture of fluid, for example water, and compressed air is then sprayed or jetted onto the transparent element 37 of the camera 12.

[0046] The exemplary embodiment according to Figure 4Figure 1 illustrates how transparent elements 37 of several cameras 12 can be cleaned. For this purpose, the piping system 19 is preferably divided upstream of the cleaning outlets 22 assigned to the cameras 12, such that preferably one cleaning outlet 22 per camera 12 is connected to the valve 18. Although three cameras 12 are shown in the exemplary embodiment, more or fewer than three cameras 12 can also be provided. This is indicated by the dotted continuation of the piping system 19. The control unit 20 uses the valve 18 to control whether fluid or compressed air, or both, are to be directed to the cleaning outlets 22. A further valve 40 can be arranged upstream of each cleaning outlet 22, which is preferably also controlled by the control unit 20.The control unit 20, by opening or closing the valves 40, controls which individual transparent elements 37 of the cameras 12 are to be supplied with cleaning fluid and / or compressed air from the corresponding cleaning outlets 22. However, all valves 40 can also be omitted. In this case, the valve 18 not only determines whether the fluid or compressed air is to be used alone or in a mixture, but also directly initiates the supply to the transparent element 37 of the cameras 12. In this case, all cameras 12, or rather their transparent elements 37, are cleaned simultaneously. The valve 18 and / or the valves 40 can be configured to regulate the flow volume. Although not explicitly shown, the other embodiments could also be designed according to the principle of... Figure 3be trained to clean a large number of cameras 12 or their transparent elements 37.

[0047] In particular, when multiple cameras are present, 12 such as in the Fig. 4 It is shown that only one camera is used as the master camera and that, in particular, its contamination is decisive for triggering a cleaning cycle for several or all cameras (the remaining cameras 12 of the soil milling machine 1 affected by this are accordingly referred to as slave cameras). With regard to the embodiment in the Fig. 1 It is particularly preferred if one of the cameras arranged on the underside of the machine frame of the soil milling machine 1 or the camera arranged on the transport device 5 is the master camera.

[0048] In Figure 5An embodiment is shown in which an additive tank 25 is provided. The additive tank 25 preferably contains an additive, for example a cleaning agent, which can preferably be mixed with the fluid of the fluid tank 14 before this mixture is applied to the transparent element 37 of a camera 12. The additive is, for example, a liquid, which is preferably introduced into a common part of the piping system 19 with the fluid from the fluid tank 14 via a pump 26, for example a gear, piston, diaphragm or water jet pump. Although not shown, this embodiment is particularly suitable for use in a system as described in Figure 4The mixing device 23 shown in the invention ensures homogeneous mixing of the additive in the fluid. Preferably, the outlet of the additive tank 25 is equipped with a valve 39. The valve 39 is also controlled by the control unit 20, for example, in response to an operator input. The control unit 20 can therefore determine, by closing or opening the valve 39, whether additive from the additive tank 25 enters the piping system 19 and thus reaches the cleaning outlet 22. The use of the additive can therefore be optionally activated or deactivated by the control unit 20. Of course, the use of a corresponding additive can also be provided for in all other embodiments of the invention.

[0049] The exemplary embodiment in Figure 6This is intended to illustrate further modifications that are applicable to all embodiments. For example, the pump 21 can be arranged not only upstream of the valve 18, as shown previously, but also downstream. A reference 29 is preferably arranged in the field of view of the camera 12, particularly in the viewing direction behind the transparent element 37 in the recording area 13 of the camera 12. The reference 29 can be, for example, a light source, a contour, or a recognizable pattern. Since it is known how the reference 29 should be represented by the camera 12 in the image information when the transparent element 37 is clean, it is possible to infer from the actual representation of the reference 29 in the recorded image information whether the transparent element 37 is contaminated. In addition, various sensors can be provided, preferably all of which are connected to the control unit 20.For example, a level sensor 30 can be provided on the fluid tank 14, which determines the fill level of the fluid tank 14 and transmits a corresponding value to the control unit 20. Similarly, a pressure sensor 31 can be provided on the compressed air tank 15. The pressure sensor 31 is also connected to the control unit 20 and transmits the measured value to it. In addition, a temperature sensor 32 can also be provided, for example. The temperature sensor 32 can be arranged at the cleaning outlet 22, as shown. Alternatively, the temperature sensor 32 could also be arranged on the piping system 19, on the pump 21, on the valve 20, or on the fluid tank 14. Like the other sensors, the temperature sensor 32 is connected to the control unit 20 and transmits the measured temperature values ​​to it.Based on the measured signals, the control unit 20 can, for example, issue warnings to an operator if the fill level or pressure has dropped too low and the tanks need to be refilled. Furthermore, a warning can be generated if the temperature sensor 32 detects that one of the aforementioned components has frozen.

[0050] Figure 7Finally, a flowchart of the method 33 is shown. The method comprises monitoring 34 the contamination of the transparent element 37 of a camera 12. Preferably, the monitoring 34 relates to the transparent elements 37 of all cameras 12 provided on the soil milling machine 1. A further step comprises detecting 35 contamination of the transparent element 37 or transparent elements 37 depending on a working situation of the soil milling machine 1 or depending on image information recorded by the camera 12. In particular, if contamination is detected, the transparent element 37 or transparent elements 37 are then supplied 36 with fluid and / or compressed air from a fluid tank 14 and / or a compressed air tank 15.After exposure 36, the process 33 starts again, so that the contamination and the associated deterioration of the image information are continuously monitored. Overall, the invention makes it possible to ensure consistently high quality of the image information provided by the cameras 12. At the same time, contamination of the transparent element 37 of a camera 12 is efficiently detected and removed.

Claims

1. A ground milling machine (1) for working soil (8), in particular a road milling machine, recycler, or stabilizer, comprising - a machine frame (3) supported by drive means (6, 38) with a driver's cab (2) for an operator, - a milling device, - at least one camera (12) for recording image information of an external environment and / or an external view of at least part of the ground milling machine (1), wherein the camera (12) has a recording area (13) with a transparent element (37) through which it records the image information, - a control device (20) that receives the image information from the camera (12), - a fluid tank (14) containing a cleaning fluid and / or a compressed air tank (15) connected to a pipe system (19), wherein a cleaning outlet (22) is provided which is connected to the pipe system via a valve (18) and / or fluid delivery device controlled by the control device (20) (19) and is designed to apply liquid fluid from the fluid tank (14) and / or compressed air from the compressed air tank (15) to the transparent element (37) for cleaning, and wherein the control device (20) is designed to initiate cleaning of the transparent element (37) depending on a working situation or depending on the image information. characterized in that the control device (20) is designed to perform a new dirt detection after cleaning and to initiate a new cleaning of the transparent element (37) if dirt is still detected, wherein, if it is determined after cleaning that the transparent element is still dirty, the control device (20) increases the flow volume of the cleaning outlet during the new cleaning and thus intensifies the cleaning.

2. Ground milling machine (1) according to claim 1, characterized in that the working situation comprises - switching the ground milling machine (1) on or off, and / or - starting or ending a working operation, and / or - starting or ending a transport operation, and / or - lowering or raising a milling drum (9), and / or - the elapse of a time interval, for example in relation to an operation or a working operation of the ground milling machine (1), and / or - reaching a distance, for example in relation to an operation or a working operation of the ground milling machine (1), and / or - reaching a threshold value of weight or volume of soil material transferred by the ground milling machine (1) to a transport vehicle, and / or - reaching a threshold value of a counter (27), for example a counter (27) for the number of machine starts or the number of transport vehicles loaded by the ground milling machine (1), and / or - the start or end of operation and / or a type of operation of a water spray system (28) for moistening the milling device and / or the removed soil material.

3. Ground milling machine (1) according to one of the preceding claims, characterized in that the control device (20) is designed to evaluate the image information as part of a dirt detection process and initiates cleaning of the transparent element (37) if the dirt detection process detects contamination of the transparent element (37).

4. Ground milling machine (1) according to claim 3, characterized in that the control device (20) is designed to use brightness and / or contrast and / or saturation and / or image sharpness and / or relative luminescence and / or pattern recognition in part of the image information or in the entire image information for dirt detection.

5. Ground milling machine (1) according to one of claims 3 to 4, characterized in that the control device (20) is designed to detect temporal changes in the image information and to recognize contamination of the transparent element (37) when the changes exceed and / or fall below a threshold value.

6. Ground milling machine (1) according to one of claims 3 to 5, characterized in that the control device (20) is designed to use a reference (29) detected by the camera (12), for example a light source, a contour or a pattern, for dirt detection.

7. Ground milling machine (1) according to one of claims 3 to 6, characterized in that the control device (20) is designed to detect a change in parts of the image information, for example individual pixels, and to detect contamination of the transparent element (37) when the proportion of the changed image information exceeds a threshold value.

8. Ground milling machine (1) according to one of claims 3 to 7, characterized in that the control device (20) is designed to evaluate the image information for contamination detection using software based on machine learning, and in that the software observes the behavior of the operator and determines, for example, under which conditions and / or in the presence of which changes the operator manually triggers a cleaning process during the ongoing work process.

9. Ground milling machine (1) according to one of the preceding claims, characterized in that it comprises at least one of the following features: - it comprises at least one and preferably a plurality of cameras (12); - it comprises a milling drum (9) mounted in a milling drum housing (7) so as to be rotatable about a rotational axis (10) for removing soil material; - it comprises a transfer conveyor belt (11) and a loading conveyor belt (5), wherein the transfer conveyor belt (11) is designed to transport milled soil material from the milling drum housing (7) to the loading conveyor belt (5) and the loading conveyor belt (5) is designed to transport the milled soil material onto a transport vehicle, wherein the camera (12) is arranged between the transfer conveyor belt (11) and the ground (8); - it comprises a pump (21) connected to the pipe system (19) for transporting fluid from the fluid tank (14); - each camera (12) has a cleaning outlet (22), with each cleaning outlet (22) having a pump (21) that supplies it with fluid, or with one pump (21) designed to supply all cleaning outlets (22) with fluid; - the cleaning outlet (22), preferably all cleaning outlets (22), and / or the fluid tank (14) are designed to be heatable; - the fluid for cleaning is provided with an additive, in particular a cleaning agent, wherein the additive is mixed with the fluid in the fluid tank (14) or wherein the additive is provided in a separate additive tank (25) and is mixed with the fluid of the fluid tank (14) outside the fluid tank (14); - a mixing device (23), in particular a static mixer, is provided for mixing the fluid with the compressed air and / or the additive.

10. Ground milling machine (1) according to one of the preceding claims, characterized in that the control device (20) comprises at least one of the following features: - it is designed to simultaneously apply fluid from the fluid tank (14) and compressed air from the compressed air tank (15) to the transparent element (37) for cleaning; - it is designed to first apply fluid from the fluid tank (14) and then compressed air from the compressed air tank (15) to the transparent element (37) for cleaning; - it is designed to first apply fluid from the fluid tank (14) and then compressed air from the compressed air tank (15) to the transparent element (37) for cleaning; - it is designed to control the valve (18) in such a way that the transparent element (37) is exposed to a continuous flow or a pulsed flow of fluid and / or compressed air from the fluid tank (14) and / or the compressed air tank (15) for cleaning; - it comprises a display device (24) arranged in the driver's cab (2) for displaying the image information; - it comprises a level sensor (30) on the fluid tank (14) and / or a pressure sensor (31) on the compressed air tank (15) and / or a temperature sensor (32) on the cleaning outlet (22), and is designed to monitor sensor signals and, in particular, to display them on the display device (24); - it is designed to initiate cleaning of a single camera (12) or of several cameras (12) or of all cameras (12) of the ground milling machine (1) simultaneously; - it is designed to control the pump (21) and / or the valve (18) in order to adjust a flow volume of the cleaning outlet (22).

11. Method (33) for cleaning a transparent element (37) arranged in a recording area (13) of a camera (12) of a ground milling machine (1) according to one of the preceding claims, comprising the steps: - monitoring (34) the contamination of the transparent element (37) of the camera (12), - detecting (35) contamination of the transparent element (37) depending on a working situation of the ground milling machine (1) or depending on image information recorded by the camera (12), and - applying (36) fluid and / or compressed air from a fluid tank (14) and / or a compressed air tank (15) to the transparent element (37).