Reducing the risk of an icy depression forming under a vehicle's tires

Abstract

The invention relates to a system for a vehicle (1) designed to detect a risk of an icy depression forming under the tires of the vehicle (1) parked on a surface (3) by detecting ice and snow on the surface (3) and by determining the ambient temperature, and if a risk of an icy depression forming is detected, to determine a second parking location different from the original parking location of the vehicle (1) depending on at least one distance between a first axle and a second axle, such that the position of the second axle at the second parking location of the vehicle (1) is different from the position of the first axle at the original parking location of the vehicle (1).

Description

The invention relates to a system for a vehicle equipped with a driving control unit for automated vehicle guidance for reducing the risk of forming an icy depression under tires of the vehicle, and to a vehicle having such a system.Heavy vehicles, in particular trucks or buses, can be particularly affected by reduced friction when parked on snow or ice. Difficulties due to reduced friction on a frozen surface when driving off can occur in particular when such a heavy vehicle with heated tires is parked on snow or ice because of a preceding longer journey. Then, in particular temperature conditions, the situation may arise in which the heated tires cause the contacting ice or the snow to melt locally, but, when the vehicle is shut down for a longer time, after the tires have cooled out, the ice or snow melted to liquid water freeze again to ice and form an icey depression around the tires. Such an icy well can have a particularly disturbing effect when the vehicle is started, since on the one hand the friction between the tyre and the icy surface of the well is very low and, in addition, the shape of the well has the effect that the vehicle has to overcome a gradient at least for a short distance, which can however become unremoved for the vehicle because of the low friction of the ice. This is also contributed by the own weight of the vehicle, which can be very high to a particular extent in trucks or buses or other heavy vehicles; compressed snow, as well as ice itself, can creep under load, i.e. deform slowly; this can contribute to the icey depression which forms under the respective tyre of the vehicle becoming even deeper and thus making it more difficult for the vehicle to start.In the prior art, the problem of reduced coefficients of friction and slopes, especially in combination with each other, has already been addressed. In this context, US 2021 / 0247769 A1 is concerned with a vehicle on which an autonomous driving system can be mounted, comprising: a vehicle platform that controls the vehicle according to an instruction of the autonomous driving system; and a vehicle control interface that represents interfaces between the vehicle platform and the autonomous driving system, wherein the vehicle control interface provides the autonomous driving system with a signal indicating a direction of movement of the vehicle determined based on a majority rule associated with rotational directions of wheels. In an embodiment of US 2021 / 0247769 A1, when a certain period of time has elapsed with zero speed of all wheels, the vehicle control interface provides the autonomous driving system with a signal indicating "standstill" as the signal indicating the direction of movement of the vehicle. Depending on the configuration, after a specific period of time has elapsed, in which the speed of all wheels is zero, a corresponding signal for indicating the stop (the signal "standstill") can be provided to the autonomous driving system.The detection of depressions or snow- or ice-covered roadway areas is also known from the prior art:For this purpose, DE 10 2015 213 193 A1 shows a control system for a hill approach aid, wherein it is provided that, in the case of a flat roadway, a local gradient of the roadway in the sense of a local depression is detected and, in this case, the hill approach aid is activated.A starting aid is known from DE 10 2019 101 704 A1, wherein provision is made to detect snow or ice covering of the roadway and to activate the starting aid as a function thereof.In the driver assistance system from DE 10 2020 117 156 A1, provision is made for a depression in the roadway region to be detected and taken into account during object recognition.In the prior art, methods are also disclosed with which an already stopped vehicle can leave its location and can be released again:US 2019 / 0111932 A1 relates to a method for this purpose, comprising the steps:creating a map having obstacles and an estimated coefficient of friction between vehicle wheels and a roadway surrounding a stuck vehicle based on sensor data; determining a path based on the map; and operating the stuck vehicle based on the path and a slip control process based on the vehicle wheels.Sending a search for help is also known in the art to request remote assistance:US 2015 / 0248131 A1 relates to a computer-implemented method for this purpose, comprising: determining a representation of an environment of an autonomous vehicle on the basis of sensor data of the environment; identifying, on the basis of the representation, a situation from a predefined series of situations for which the autonomous vehicle requests remote assistance; sending a search for assistance to a remote assistant, wherein the searching comprises the representation of the environment and the determined situation; receiving a response from the remote assistant, which response points to an autonomous operation; and causing autonomous operation of the autonomous vehicle.The general subject matter of reduced friction is assumed by the following publication, which determines a road state and a road friction coefficient based on the predicted road friction coefficient, in particular by means of an image.KR 10 2022 0 007 970 A relates to division / prediction of a road friction coefficient into finer ranges and use of the information for autonomous control so that the running state of an autonomous vehicle can be securely maintained even in bad weather with rain or snow. According to an embodiment, the method includes a step of using an image and estimating a road condition; a step of predicting a road friction coefficient based on the estimated road condition; a step of generating brake control information when braking is required during running; and a step of correcting the generated brake control information using the predicted road friction coefficient. Accordingly, it is possible to predict road friction.While requesting help or means for coming off an already stopped vehicle represent reactions to the already occurred stop situation, it is desirable to prevent the stop from the beginning. It is therefore the object of the invention to provide a system which helps to avoid a vehicle from being stuck, in particular a heavy vehicle such as a truck or a bus.The invention results from the features of the independent claims. Advantageous refinements and refinements are the subject matter of the dependent claims.A first aspect of the invention relates to a system for a vehicle, in particular a truck, equipped with a travel control unit for automated vehicle guidance, wherein the system is designed to determine a risk of forming an icy well under tires of the vehicle placed on a ground or still to be placed by detecting ice and / or snow on the ground and by determining an air temperature and / or a temperature of the ground, and if a risk of forming an icy well is detected, to determine a second place different from an original place of deposit of the vehicle depending on at least one distance between a first axis and a second axis of the vehicle, such that the position of the second axis (position relative to the underlying surface) at the second parking location of the vehicle is different from the position (position relative to the underlying surface) of the first axis at the original parking location of the vehicle, and wherein the system is configured to command the driving control unit of the vehicle to assume the second parking location of the vehicle after a predefined time period after the assumption of the original parking location.In principle, the second parking location of the vehicle could be selected against the main direction of travel of the original parking location of the vehicle. However, it is undesirable and as far as possible to avoid driving backwards, particularly in trucks, since the risk of a collision with an obstacle or a person increases therewith and is considerably higher than in a forward drive. If it is accordingly assumed that the second parking location of the vehicle is selected in front of the original parking location of the vehicle in the main direction of travel of the vehicle, the position of the first considered axis advantageously lies in front of the position of the second axis which is considered. Advantageously, it is thus prevented that the wheels of a further axle enter an already initially formed icy trough of another axle, and this icy trough is correspondingly recessed. Depending on the number of axles of the vehicle, not only the wheels and tires of only two axles of the vehicle are to be considered here, but advantageously all (at least the driven) axles of the vehicle in pairs with respect to one another, for which a paired common assumption of a location on the underlying surface starting from the original parking location toward the second parking location is possible.The assumption of a second parking location compared to the original parking location can be repeated in any number of iterations, so that a third and a fourth parking location are assumed after respective predefined time periods. The method of the system described above and in the following can be applied unchanged to the different pairs of storage locations in each case, wherein the respective original storage location is a respective current storage location and the respective second storage location is a storage location changed to this original storage location, so that the terms of the original storage location and of the second storage location can be relative terms to pairs of storage locations. The repetition preferably takes place as long as a difference between a current tire temperature and a current ambient temperature (or alternatively a temperature of the underlying surface) falls below a predefined fifth limit value.The vehicle is equipped with a travel control unit which is designed to move and steer the vehicle even without a human driver, i.e. to carry out the complete vehicle guidance of the vehicle and therefore also automatically to move the vehicle which has been parked at the original parking location to the second parking location.The determination of the air temperature can be carried out using a thermometer arranged on the vehicle, but can also be taken with its current value from a central database, in particular using a digital map and the current position of the vehicle. The determination of the temperature of the underlying surface can likewise be determined via corresponding model calculations, information from central databases and associated position information of the vehicle; in principle, it can also be determined directly by radiation thermometers which are arranged on the vehicle, in order to determine a respectively current temperature of the underlying surface on the basis of the thermal radiation of the underlying surface. In rare cases, weather phenomena may occur in which the air temperature is considerably higher or considerably lower than the temperature of the substrate. In order to be able to take account of such weather phenomena, the temperature of the underlying surface and the air temperature are advantageously determined and the risk of forming an icy trough is determined from the combination of the two.Furthermore, the system advantageously determines an expected service life at the original parking location and takes into account a weather forecast. If the original parking location is located at the end of the traffic jam on a freeway, then a spontaneous renewed movement of the vehicle must be assumed and therefore advantageously only the current air temperature or the current temperature of the underlying surface must be taken into account. However, if the vehicle is to remain at the original parking location for several days, for example, then the weather forecast can be helpful in estimating the risk of forming an icy well.It is therefore an advantageous effect of the invention that the risk of forming an icy well is reduced, and when this begins to form at the original parking location, the vehicle does not remain in it for too long a time, so that this is not yet so deep that the vehicle could not free itself from this icy well under its own force. By moving the vehicle from the original parking location to the second parking location, the initial cooling of the tires in the cold air and on the cold ground is utilized in order to be able to approach and assume the second parking location with already cooled tires. The formation of a further icy well at the second parking location will thus be significantly less, wherein, in the case of a continuing risk of the formation of a likewise too deep icy well at the second parking location, the method can be repeated by the system and the vehicle can be displaced again. The risk that the vehicle will be caught in an icy well after remaining at the original parking location for too long a period of time is thus advantageously significantly reduced by the method carried out by the system.According to an advantageous embodiment, the system is designed to detect a risk of forming an icy depression only when the time length of a preceding trip of the vehicle exceeds a predefined first limit value, and / or when a current tire temperature determined by means of a tire temperature sensor unit of the system exceeds a predefined second limit value when the original parking location is taken.The tire temperature sensor unit is advantageously designed as an infrared camera, which is designed to ascertain thermal radiation and to ascertain a current temperature of at least one tire on the basis of intensity and / or frequencies of the thermal radiation radiated by the tires. If, on the other hand, no temperature sensors are present for determining the temperature of at least one of the tires, a heuristic can also be used which is estimated, in particular, from the load of the vehicle, the duration of the immediately preceding travel of the vehicle, and the ambient temperature and / or the temperature of the underlying surface, a temperature or a temporal temperature profile of one or more tires of the vehicle.According to a further advantageous embodiment, the system is designed to detect a risk of forming an icy trough only if the air temperature and / or the temperature of the subsurface is below a predefined third limit value.The third predefined limit value is preferably the freezing point, namely 0° C., further preferably -2° C.According to a further advantageous embodiment, the system is designed to determine the second parking location as a function of at least one distance between two driven axles of the vehicle, such that the position of the second driven axle at the second parking location of the vehicle is not equal to the position of the first driven axle at the original parking location of the vehicle.According to a further advantageous embodiment, the system is designed to determine the second parking location as a function of the respective paired distance of all axles of the vehicle that are possible for a potential overlap of the positions of the tires associated with the axles on the underlying surface between the original and second parking location.According to a further advantageous embodiment, the system has a camera for detecting a ground in the environment of the vehicle, and is designed to carry out image recognition on the basis of the data of the camera and to recognize ice and / or snow on the ground.According to a further advantageous embodiment, the system is designed to detect the risk of forming an icy trough on the basis of a heuristic relationship which comprises at least one air temperature and / or a temperature of the underlying surface and has as an initial value a probability for the risk of forming an icy trough, wherein a risk of forming an icy trough is detected when the probability is exceeded above a predefined fourth limit value.According to a further advantageous embodiment, the system is designed to already determine the original parking location in such a way that sufficient maneuvering length remains in front of the vehicle to be able to assume the determined second parking location of the vehicle.This therefore also includes the detection of a traffic jam, for example on a freeway, and if such a traffic jam is detected, the system causes the vehicle to assume a parking location in front of the traffic jam at a sufficient distance from the end of traffic jam, so that the vehicle has sufficient distance from the end of traffic jam in the given direction of travel on the road or on the lane being traveled by the vehicle, in order to be able to assume the second parking location as determined.According to a further advantageous embodiment, the system is designed to determine the predefined time duration for assuming the second parking location of the vehicle after the assuming of the original parking location as a function at least of the determined air temperature and / or the temperature of the underlying surface.Furthermore, the system can take into account the current tire temperature and / or the duration of the preceding trip and / or an average speed in the preceding trip and / or a loading state of the vehicle and / or the total mass of the vehicle. The same parameters which are used to determine a risk for the formation of an icy well can thus also be used to determine the time duration after which the vehicle is moved to the second parking location since the time of the assumption of the original parking location of the vehicle.Furthermore, the system is preferably designed to also determine this predefined time duration as a function of a current tire temperature and / or the time duration of an immediately preceding journey of the vehicle. Thus, the speed at which the formation of such an icy well could take place is advantageously taken into account. Namely, the warmer the tires, the faster the vehicle with its tires sink into the frozen surface (in snow or ice); the lower the temperature of the underlying surface as well as the temperature of the ambient air, the faster the tires cool down and the faster the molten water re-freeze in the form of a frozen and thus icy trough.A further aspect of the invention relates to a vehicle having a system as described above and below.Advantages and preferred refinements of the proposed vehicle result from an analogous and analogous transfer of the explanations given above in connection with the proposed system.Further advantages, features and details are evident from the following description, in which--possibly with reference to the drawing--at least one exemplary embodiment is described in detail. Identical, similar and / or functionally identical parts are provided with the same reference numerals.It shows: FIG. 1 : A system for reducing the risk of forming an icy depression under tyres of a vehicle according to an exemplary embodiment of the invention.The representations in the figure are schematic and not to scale.FIG. 1 shows a truck as vehicle 1 over times (A) to (F), truck 1 having a travel control unit for automated vehicle guidance. The system first checks whether there is generally a risk of forming an icy well under tyres of the truck 1 placed on a ground 3 or still to be placed. For this purpose, during the approach in step (A), the system still uses a camera 5, which is directed onto the underlying surface in the immediate vicinity of the truck 1. By executing a first artificial neural network on the image data of the camera 5, it is checked by means of image recognition whether ice and / or snow is at a significant height on the ground. If this is the case, a potential risk of forming an icy depression under the tires of the truck 1 must generally be assumed when the truck is parked on this ice or on the snow. Furthermore, the system determines a current air temperature, a current temperature of the underlying surface 3, and a current temperature of at least one of the tires of the truck 1. By executing a second artificial neural network on the basis of all the determined temperature conditions of air, underlying surface and tire with respect to one another and optionally an estimate of the thickness of the ice or of the snow on the underlying surface, a probability for the formation of an icy depression under the respective tires of the truck 1 is determined. If this probability exceeds a predetermined threshold value, the system determines a time period which is considered safe to let the truck 1 stand at its original parking location. After this period of time has elapsed, the system instructs a travel control unit of the truck 1 in such a way that the truck 1 is moved automatically from its original parking location to a second parking location. Within this period of time, i.e. before the movement to the second parking location, the initial formation of an icy trough takes place at the original parking location in partial image (B), as outlined in partial image (C). Such icy troughs begin to form under all wheels below the tire surface of the truck 1. The second parking location of the truck 1 is determined by the system in such a way that it is located in front of the original parking location in the main direction of travel of the truck 1, namely in such a way that none of the wheels having the tires comes to rest at a position at the second parking location of the truck 1 at which another tire of a wheel of the truck 1 has already come to rest at the original parking location of the truck 1. This can be seen in partial image (D), according to which the truck 1 has moved by half the distance between two adjacent axes of the semi-trailer and of the semi-tractor from the original position at the original parking location to the second parking location. After a further period of time, the process is repeated and the truck 1 is moved over the underlying surface 3 once again by an even greater distance, so that the truck 1 with its tires touches the underlying surface 3 at positions which were not touched by the tires at the first two original parking locations. The result is shown in field (E). The truck 1 has thus been parked at the last second parking location at a position of the underlying surface 3 at which it has been parked with the tires virtually completely cooled. It is therefore easily possible to drive off the truck 1 since only the weight force has somewhat compressed the frozen underlying surface 3, but an additional heat of the wheels and tires of the truck 1 was hardly present any longer and thus did not contribute to the formation of an icy depression below each tire.Although the invention has been illustrated and explained in more detail by preferred exemplary embodiments, the invention is not restricted by the disclosed examples and other variations can be derived therefrom by the person skilled in the art without departing from the scope of protection of the invention. It is therefore clear that a large number of possible variations exist. It is also clear that embodiments mentioned by way of example represent only examples which are not to be understood in any way as limiting, for example, the scope of protection, the possible applications or the configuration of the invention. Rather, the preceding description and the description of the figures enable the person skilled in the art to implement the exemplary embodiments in concrete terms, wherein the person skilled in the art, knowing the disclosed inventive concept, can make various changes, for example with regard to the function or the arrangement of individual elements mentioned in an exemplary embodiment, without departing from the scope of protection defined by the claims and their legal equivalents, such as further explanations in the description.

Claims

System for a vehicle (1) equipped with a travel control unit for automated vehicle guidance, in particular a truck, wherein the system is designed to determine a risk of forming an icy well under tyres of the vehicle (1) placed on a ground (3) or still to be placed by detecting ice and / or snow on the ground (3) and by determining an air temperature and / or a temperature of the ground (3), and if a risk of forming an icy well is detected, to determine a second place of placement different from an original place of placement of the vehicle (1) depending on at least one distance between a first axis and a second axis of the vehicle (1), such that the position of the second axis at the second parking location of the vehicle (1) is different from the position of the first axis at the original parking location of the vehicle (1), and wherein the system is configured to command the driving control unit of the vehicle (1) to assume the second parking location of the vehicle (1) after a predetermined period of time after the assumption of the original parking location.The system according to claim 1, wherein the system is configured to detect a risk of forming an icy trough only if the time length of a preceding trip of the vehicle (1) exceeds a predefined first limit value, and / or if a current tire temperature determined by means of a tire temperature sensor unit of the system exceeds a predefined second limit value when the original parking location is taken.The system according to any one of the preceding claims, wherein the system is configured to detect a risk of forming an icy trough only if the air temperature and / or the temperature of the subsurface (3) is below a predetermined third threshold value.The system according to any one of claims 1 to 3, wherein the system is configured to determine the second parking location depending on at least one distance between two driven axles of the vehicle (1), such that the position of the second driven axle at the second parking location of the vehicle (1) is not equal to the position of the first driven axle at the original parking location of the vehicle (1).System according to one of Claims 1 to 3, wherein the system is designed to determine the second parking location on the basis of the respective paired spacing of all axles of the vehicle (1) which are possible for a potential overlap of the positions of the tires associated with the axles on the underlying surface between the original and second parking locations.The system according to any one of the preceding claims, wherein the system comprises a camera (5) for detecting a ground (3) in the environment of the vehicle (1) and is configured to perform image recognition and to recognize ice and / or snow on the ground (3) on the basis of the data of the camera (5).The system according to any one of the preceding claims, wherein the system is configured to detect the risk of forming an icy trough on the basis of a heuristic relationship comprising at least an air temperature and / or a temperature of the subsurface (3) and having as an initial value a probability for the risk of forming an icy trough, wherein a risk of forming an icy trough is detected when the probability is exceeded above a predetermined fourth threshold value.The system according to any one of the preceding claims, wherein the system is designed to already determine the original parking location such that there is sufficient maneuvering length in front of the vehicle (1) to be able to assume the determined second parking location of the vehicle (1).The system according to any one of the preceding claims, wherein the system is configured to determine the predefined time duration for assuming the second parking location of the vehicle (1) after assuming the original parking location as a function of at least the determined air temperature and / or the temperature of the underlying surface (3).Vehicle (1) comprising a system according to one of the preceding claims.

Images