DE102022106967B4 - Method for operating a radar sensor unit, radar sensor unit and motor vehicle - Google Patents

Abstract

Method for operating a radar sensor unit (2) of a motor vehicle (1), which is arranged behind a protective element (6) on the motor vehicle (1) that can be heated by a heating device (5) and is essentially transparent to radar radiation, wherein by a control device (7) a first attenuation value is determined, which characterizes a visibility range of the radar sensor unit (2), and depending on the determined first attenuation value and / or at least one environmental parameter, a heating power with which the heating device (5) heats the protective element (6) is determined, and after the first damping value, a second damping value is determined and an efficiency value is formed by comparing the two damping values, and the heating output is adjusted depending on the efficiency value.

Description

The invention relates to a method for operating a radar sensor unit of a particularly electrically driven motor vehicle according to patent claim 1. The invention further relates to a radar sensor unit for a motor vehicle according to patent claim 9. Finally, the invention relates to a motor vehicle according to patent claim 10.

Radar sensors or radar sensor units can be designed as front radar sensors and thus be arranged on the front of a vehicle. In order to be protected from environmental influences, for example falling rocks, the radar sensor unit and in particular its transmitting and/or receiving unit is usually installed behind a protective element, for example a radome. This radome can be provided with a heater to enable the radar sensor to be available, for example when precipitation freezes over. The heater can include a heating wire and/or a heating foil.

This sensor availability may be necessary for the associated availability or functionality of a driver assistance function - for example adaptive cruise control, emergency braking assistant, cross traffic warning. A heater can be particularly beneficial in cold temperatures when there is snow and/or rain. Without heating, for example, a layer of snow or ice could clog the protective element, which could limit the sensor range or visibility to the point of complete blindness. In such a case, the driver assistance functions mentioned would have to be dispensed with.

The DE 10 2004 028 860 B4 shows an object detection device intended to detect adhesion of dirt to a radar. Furthermore, it shows EP 2 138 352 B1 an optical system for detecting optical fogging in a vehicle.

Furthermore, the reveals DE 10 2020 000 291 A1 a method for heating a radar sensor of a vehicle. In the method, the heating element is only activated when, in addition to a temperature drop, the radar sensor detects that a radiation-hindering layer adheres to the vehicle in its beam path and/or a rain sensor detects precipitation.

In addition, the describes DE 10 2017 221 589 A1 a heating system for a radome with a control unit which is set up to receive or determine a variable that is characteristic of an outside temperature, to receive or determine a variable associated with a melting point of precipitation deposits on an outer radome surface, at least a temperature threshold depending on the To determine the melting point-related size, and to activate the heating element depending on a threshold comparison of the outside temperature with the temperature threshold.

In general, it is desirable to carry out the heating of the protective element particularly efficiently, especially in electrically powered motor vehicles. It is therefore the object of the present invention to provide a method for operating a radar sensor unit, a radar sensor unit and a motor vehicle, which heat particularly energy-efficiently, in particular depending on environmental or condition parameters of the motor vehicle.

This object is achieved according to the invention by the subject matter of the independent patent claims. Advantageous refinements and further developments of the invention are specified in the dependent patent claims as well as in the description and in the drawing.

A first aspect of the invention relates to a method for operating a radar sensor unit of a motor vehicle, which is arranged behind a protective element on the motor vehicle that can be heated by a heating device and is essentially transparent to radar radiation.

The protective element is in particular a radome and can serve as protection against stone chips and/or weather protection. Essentially transparent to radar radiation means that attenuation or absorption of radar radiation by the material that forms the protective element is low, in particular in comparison to the radar radiation transmitted through the material. For example, the transmission can be at least a factor of 10 greater than the absorption.

The radar sensor unit can emit electromagnetic waves in the radio frequency range and thus radar waves, on the one hand, for example by means of a transmitting unit, and on the other hand, can receive them, for example by means of a receiving unit. The received radar waves or radar beams are reflections of the emitted radar waves from objects in a motor vehicle environment. The radar sensor unit can be used to provide a detection or location method, for example for vehicle assistance systems.

In order to operate the radar sensor unit particularly efficiently depending on, for example, environmental influences and/or motor vehicle conditions by operating the heating device for the protective element particularly efficiently, in the method according to the invention a first attenuation value is determined by means of a control device, which characterizes a visibility range of the radar sensor unit, and Depending on the determined first damping value and/or at least one environmental parameter, a heating power for the heating device is determined, with which the heating device heats the protective element. After the first damping value, a second damping value is determined and an efficiency value is formed by comparing the damping values, i.e. the first damping value with the second damping value, and the heating output is adjusted depending on the efficiency value. The fact that the second attenuation value is determined after the first attenuation value means that there is a first time interval between the two times of determination.

Thus, on the one hand, the protective element can be heated by means of the heating device with the heating power first determined by the method, for example to prevent or at least minimize an accumulation of snow and/or ice on the protective element, in particular the radome. In addition and beyond this, the method can be used to determine, based on the repeated determination of the attenuation value, what effect the heating has on the attenuation and thus on the visibility of the radar sensor unit. In this way, the heating output can advantageously be adjusted accordingly.

A typical heating device for the protective element is operated with a heating output of around 100 watts. In the temperature range in which the heater is usually used, the prior art always heats depending on the speed with up to 100% of the available heating power, regardless of the actual efficiency of the heating operation. This may result in unnecessary energy being consumed and the range of the vehicle being reduced.

If the efficiency value shows that no improvement in visibility is achieved through heating, for example due to adverse weather conditions, icing is so great that even the maximum heating output of the heating device is not sufficient to free the radome or the protective element from ice, It makes sense to reduce the heating output. In particular, the heating can be switched off so that the heating output is zero. As a result, the energy required for heating can be saved, which means that the motor vehicle can be operated with an increased range, for example.

The invention is based on the finding that to determine the heating output in the prior art, for example, the vehicle speed can be used as a proportionality factor, since, in particular in the case of a radar sensor unit arranged at the front of the motor vehicle, an air flow caused by the speed of the motor vehicle is particularly noticeable This can result in the protective element icing up or becoming dirty, since heat is dissipated depending on the speed.

Thus, for example, the at least one environmental parameter is a vehicle speed. Additionally or in addition, a temperature, in particular of the motor vehicle environment, is also suitable for the environmental parameter. A further additional condition and thus a further environmental parameter can represent blindness detection, which detects when the radar sensor unit cannot detect anything, meaning that its visibility is zero and it can be considered blind, so to speak.

In summary, by using the attenuation estimate, the method according to the invention can be used to determine whether it makes sense to heat the radome. In very adverse weather conditions, especially heavy snowfall, when the heating output is not sufficient and the radome becomes more and more clogged despite maximum heating output, unnecessary heating and the associated unnecessary energy consumption can be prevented. A particular advantage of the method is that the motor vehicle can be operated particularly efficiently.

In an advantageous embodiment of the invention, the efficiency value is formed by subtracting the second damping value from the first damping value. In other words, the difference value between the two damping values is formed, with the previously determined damping value being subtracted from the last determined damping value. Since the second attenuation value is measured or determined after the first attenuation value, the first time interval passes in between. This first time interval can be used, for example, to carry out the procedure repeatedly and to check the efficiency value. With this proposed simple difference, which is the basis of the efficiency value, it can be seen that a value less than or equal to zero means that heating cannot release the protective element. The heating output can be adjusted accordingly. The advantage here is that the efficiency value can be formed in a particularly advantageous manner and the method can therefore be carried out particularly efficiently.

In a further advantageous embodiment of the invention, the efficiency value corresponds to a slope of a curve plotted over time and formed from attenuation values. In other words, the damping value is recorded at regular, in particular short, time intervals and in particular continuously, with these recorded or determined damping values being plotted over time and forming a curve there. The efficiency value can be deduced from the slope of the curve, which can be formed, for example, using the first derivative. This has the advantage that the efficiency value can be determined particularly precisely and/or particularly regularly. Another advantage is the particular efficiency of the method presented.

In a further advantageous embodiment of the invention, the heating of the protective element is adjusted when the efficiency value is less than or equal to zero. In other words, the heating power is regulated to zero or assumes the value zero, so that the protective element is not heated by the heating device. This makes it possible to react in particular to adverse weather conditions. This results in the advantage that the motor vehicle can be operated particularly efficiently and/or a particularly large amount of heating energy can be saved.

In a further advantageous embodiment of the invention, the heating is set for a second predetermined time interval, after which the heating is continued. Additionally or alternatively, heating continues when the at least one environmental parameter changes. In other words, after the second predetermined time interval, the previously interrupted heating is continued and then the process or at least part of the process is repeated in order to determine whether the heating can now be carried out efficiently. Additionally or alternatively, the at least one environmental parameter is registered and it is determined whether there has been a change in it, for example a reduction in the speed of the motor vehicle and/or an increase in temperature, then heating is also continued. In particular, due to the changed environmental parameter, for example, a heating power that can be provided by the heating device is now sufficient to improve an efficiency value and / or reduce attenuation, whereby the visibility of the radar sensor unit can now be increased. This allows the method to be carried out particularly efficiently and advantageously.

In an advantageous embodiment of the invention, the heating output is adjusted when the efficiency value is greater than zero and/or greater than a, in particular predetermined, threshold value. In other words, if the efficiency value can be interpreted in such a way, in particular by the control device, that visibility can be increased by heating, especially taking into account the attenuation, the heating can be adjusted. For example, if it is shown that the visibility can be improved through heating and this is sufficient for, for example, a required or used driver assistance function, a heating output can be reduced. This results in the advantage that the method can be used particularly advantageously to save energy.

In a further advantageous embodiment of the invention, the at least one environmental parameter is a temperature of a vehicle environment and/or a temperature of the protective element and/or a speed of the motor vehicle and/or a blindness value of the radar sensor unit. In other words, the heating power to be applied is determined as a function of a temperature, which is in particular an outside temperature and thus characterizes the vehicle environment, and/or of a temperature of the protective element and of the transmitting unit and/or the receiving unit, which thus describes a vehicle condition. This creates the possibility that a correlation can be established in a particularly advantageous manner between attenuation or attenuation value and possible icing of the protective element, whereby a heating output can be determined particularly efficiently.

Additionally or alternatively, the heating output is determined depending on the speed at which the motor vehicle moves relative to an environment. In particular, in the case of a radar sensor unit arranged on the front of the vehicle, heat can be dissipated from the radar sensor unit, in particular its protective element, due to a wind, as a result of which icing of the protective element can occur to an increased extent. By taking the speed into account when determining the heating power, there is the advantage that the protective element can be heated in a particularly advantageous manner.

Additionally or alternatively, a blindness detection of the radar sensor unit is used, which describes a failure of object detection by the radar sensor unit. This means that complete attenuation can be concluded be, whereby in particular, for example, an initial heating power can be selected to be particularly high in order to be able to ensure availability of the radar sensor unit particularly quickly. This results in the advantage that the method can be carried out particularly advantageously.

In a further advantageous embodiment of the invention, the attenuation value is determined by determining a signal difference between a radar signal sent by the transmitting unit and the particularly corresponding radar signal reflected by an object and received by the receiving unit. In other words, a difference, for example in the transit time and/or intensity and/or waveform, between the input and output signals of the radar sensor unit is used to determine an attenuation or the attenuation value. This allows, for example, the visibility range of the radar sensor unit to be determined in a particularly advantageous manner, whereby this can be correlated with a required visibility range and the degree of contamination of the protective element. This allows efficient heating to be achieved in a particularly advantageous manner. A device according to the invention

A second aspect of the invention relates to a radar sensor unit for a motor vehicle, which is designed to carry out a method according to the first aspect of the invention

Advantages and advantageous refinements of the first aspect of the invention are to be viewed as advantages and advantageous refinements of the second aspect of the invention and vice versa.

A third aspect of the invention relates to a motor vehicle which is designed to carry out a method according to the first aspect of the invention and/or has a radar sensor unit according to the second aspect of the invention.

Advantages and advantageous embodiments of the first and second aspects of the invention are to be viewed as advantages and advantageous embodiments of the third aspect of the invention and vice versa.

In particular, the radar sensor unit according to the invention is arranged on a vehicle front of the motor vehicle according to the invention. In other words, the radar sensor unit is a front sensor unit which is designed to detect the surroundings of the motor vehicle to the front. This results in the advantage that the forward visibility of the radar sensor unit can be made particularly sustainable.

Advantages and advantageous embodiments of the first and second aspects of the invention are to be viewed as advantages and advantageous embodiments of the third aspect of the invention and vice versa.

Further features of the invention emerge from the claims, the figures and the description of the figures. The features and combinations of features mentioned above in the description as well as the features and combinations of features mentioned below in the description of the figures and/or shown in the figures alone can be used not only in the combination specified in each case, but also in other combinations or on their own.

• 1 eine schematische Ansicht eines Kraftfahrzeugs mit einer Radarsensoreinheit, welche durch ein Verfahren betreibbar ist;
• 2 ein schematisches Diagramm einer Dämpfung der Radarsensoreinheit aufgetragen über die Zeit;
• 3 ein weiteres schematisches Diagramm mit der Dämpfung, einer Heizleistung und einer Stromschaltung über die Zeit; und
• 4 ein weiteres schematisches Diagramm der Dämpfung, Heizleistung und der Stromschaltung über die Zeit.

The invention will now be explained in more detail using a preferred exemplary embodiment and with reference to the drawings. It shows:

• 1 a schematic view of a motor vehicle with a radar sensor unit, which can be operated by a method;
• 2 a schematic diagram of attenuation of the radar sensor unit plotted over time;
• 3 another schematic diagram with attenuation, heating power and a current circuit over time; and
• 4 another schematic diagram of attenuation, heating power and current switching over time.

1 shows a schematic view of a motor vehicle 1, which has a radar sensor unit 2. The radar sensor unit 2 includes a transmitting unit 3 and a receiving unit 4, which could in particular also be designed as a common transmitting/receiving unit. In particular, to protect against environmental influences, the transmitting unit 3 and the receiving unit 4 are arranged behind a protective element 6 that can be heated by a heating device 5 and is essentially transparent to radar radiation.

In the exemplary embodiment shown, the radar sensor unit 2 is arranged in particular on a vehicle front, so that in particular the protective element 6 forms an outer skin element of the vehicle front of the motor vehicle 1. Essentially transparent to radar radiation means that a transmission of radar beams through the material forming the protective element is greater than their absorption in the material.

Depending on environmental influences, such as vehicle speed and/or weather, especially temperature together If there is moisture, contamination can occur on the protective element 6, which limits the visibility or detection capability or object recognition capability of the radar sensor unit 2. The pollution can occur, for example, as icing. Due to the reduction in object recognition ability or reduction in visibility caused by contamination, the radar sensor unit 2 can no longer be used for driving assistance functions, for example.

In order to prevent this and to save energy particularly advantageously in order not to negatively influence the range of a particularly electrically driven motor vehicle 1, a control device 7 is provided, which can determine the damping value. These characterize the visibility of the radar sensor unit 2.

The control device 7 can be used to determine a heating output of the heating device 5 as a function of a first determined damping value and/or at least one environmental parameter, so that the protective element 6, for example a radome, can be heated by the heating device 5 using the determined heating output.

Thus, both the motor vehicle 1 and the radar sensor unit 2 can each be designed to carry out a method for operating the radar sensor unit 2, in which a first attenuation value is determined by the control device 7, which characterizes a visibility range of the radar sensor unit 2 and depends on the determined Damping value and / or at least one environmental parameter, a heating power is determined with which the heating device heats the protective element 6, wherein in the method after the first damping value a second damping value is determined and an efficiency value is formed by comparing the damping values, and depending on that The heating output is adjusted according to the efficiency value.

It can thus arise that an attenuation estimate, i.e. determining or determining the first and/or second attenuation value and the efficiency value derived therefrom, makes it possible to determine that the heating power is incorrectly selected, for example because the selected heating power is not sufficient for the visibility of the radar sensor unit 2 to improve. In very adverse weather conditions, for example heavy snowfall and/or freezing rain, for example in combination with high vehicle speed, the maximum heating output that can be achieved may not be sufficient to protect the protective element 6 from being clogged, for example by a layer of ice. In this case, the presented method, the presented radar sensor unit 2 and the presented motor vehicle 1 can prevent unnecessary heating and the associated unnecessary energy consumption, whereby, for example, the range of the motor vehicle can be increased in a particularly advantageous manner.

For example, the motor vehicle 1 can be traveling at 100 kilometers per hour in heavy snow at an outside temperature of 0 degrees. The heating device 5 is controlled with maximum heating power. Nevertheless, due to the heavy snowfall, the radar sensor unit 2 or the protective element 6 becomes so clogged that the heating output is not sufficient to keep the radome clear while driving. The radar sensor unit 2 will therefore detect a reduced range due to the increased attenuation, i.e. a shortened visibility range. The radar sensor unit 2 or the control device 7 can determine that despite the maximum possible heating power applied, the sensor range or visibility does not increase again over time. This means that the attenuation does not reduce below a certain threshold because the attenuation value or the efficiency value is greater than a threshold value, so free heating is not possible. The radome heating can be deactivated after a configurable time window or a first time interval has been exceeded. This saves energy and the range of the motor vehicle 1 is not reduced by the unnecessary energy consumption of pointless heating.

It is advantageous if the heating of the protective element 6 is adjusted when the efficiency value is less than or equal to zero. This means that the heating output takes on the value zero when the heating or heating is set. An efficiency value less than or equal to zero means that the second damping value and thus the damping is at least equal to or higher than the first damping value.

Advantageously, if the efficiency value is greater than zero and/or greater than a threshold value, the heating output is also adjusted. The setting of the heating, i.e. the interruption of the heating or the minimization of the heating output to the value zero, can take place for a second predetermined time interval, after which the heating is continued. Additionally or alternatively, heating can be continued if the at least one environmental parameter changes.

Advantageously, a degree of contamination, for example in the form of snow and/or ice deposits, for the protective element 6 is determined based on the damping value and the heating output is determined or adjusted depending on the degree of contamination. This results in the advantage that, in a particularly advantageous manner, only as much heating power as is actually required is used to heat the protective element, for example in order to clear it of snow and/or ice. Furthermore, water that is not frozen can be caused to evaporate by heating, for example in order to increase the visibility of the radar sensor unit 2.

The at least one further parameter is in particular a speed of the motor vehicle. Additionally or alternatively, the at least one further parameter can describe a temperature of a vehicle environment and/or a temperature of the protective element 6 and/or the transmitting unit 3 and/or the receiving unit 4.

Advantageously, to determine the heating power, not only one further parameter, but at least two further parameters are used in combination with the determined attenuation value. It is advantageous, in particular, to use one of the temperatures mentioned together with the speed, whereby the required heating power can be determined particularly precisely.

Additionally or alternatively, a blindness value, which describes the blindness of the radar sensor unit, can also be used as the at least one further parameter. If using the blindness value shows that, for example, no objects in the vicinity of the motor vehicle 1 can currently be detected by the radar sensor unit 2, the heating power can be set to be particularly high in order to remove the contamination as quickly as possible.

In order to determine the attenuation value and thus attenuation caused in particular by contamination in a particularly advantageous manner, a signal difference between a radar signal sent by the transmitting unit and a radar signal reflected by an object in the vicinity of the motor vehicle and received by the receiving unit can be determined for determining the attenuation value. A simple alternative for determining the attenuation value could also be made possible, for example, by an optical detection unit, for example a camera, which is aimed in particular at an outside of the protective element.

2 shows a schematic diagram of the attenuation and thus the determined or recorded attenuation values plotted over time t. An activation threshold AS and thus a threshold value is defined, from which the heater or heating device 5 can be activated when such a damping occurs, this taking place for the period t ₁ .

In order to derive the efficiency value from the diagram, for example, the efficiency value can be the slope of the gradient plotted over time and formed from the damping values and in 2 correspond to the curve shown. After the time interval t ₁ has ended, a check is made to see whether an efficiency value has changed. The heating is deactivated for the period t ₂ , for example. After the period or time interval t ₂ , the efficiency value is evaluated again and, depending on the size of the efficiency value, heating can be carried out again. The dashed lines represent possible courses of attenuation both in the period t ₁ and after the time interval t ₂ .

Another example shows 3 , in which a schematic diagram of the attenuation and the heating power as well as a current circuit or the flow of the circuit over time is displayed. The activation threshold is reached at time T ₁ . Now heating is carried out with maximum heating power until time T ₂ , whereby it can be seen that the attenuation has increased up to time T ₂ despite heating. Now, due to the method, the circuit is interrupted at time T ₂ and the heating is switched off, whereby energy can be saved in a particularly advantageous manner. This shows that the attenuation increases and at the activation threshold AS, the heating is switched on, for example, with maximum heating output.

4 shows another example of a diagram, showing how depending on the attenuation and its increase and decrease, the heating power can be regulated increasing and decreasing and the heating power can also be completely reduced, which can be seen from the circuit shown.

The method shown, the radar sensor unit 2 and the motor vehicle 1 show a particularly advantageous damping-based control of a radome heater.

Reference symbol list

1

motor vehicle

2

Radar sensor unit

3

Transmitting unit

4

Receiving unit

5

Heating device

6

Protective element

7

Control device

t1

first time interval

t2

second time interval

T1

first time

T2

second time

AS

Activation threshold

Claims (10)

Method for operating a radar sensor unit (2) of a motor vehicle (1), which is arranged behind a protective element (6) on the motor vehicle (1) that can be heated by a heating device (5) and is essentially transparent to radar radiation, wherein by a control device (7) a first attenuation value is determined, which characterizes a visibility range of the radar sensor unit (2), and depending on the determined first attenuation value and / or at least one environmental parameter, a heating power with which the heating device (5) heats the protective element (6) is determined, and after the first damping value, a second damping value is determined and an efficiency value is formed by comparing the two damping values, and the heating output is adjusted depending on the efficiency value. Procedure according to Claim 1 , characterized in that the efficiency value is formed by subtracting the second damping value from the first damping value. Procedure according to Claim 1 or 2 , characterized in that the efficiency value corresponds to a slope of a curve plotted over time and formed from the attenuation values. Method according to one of the preceding claims, characterized in that the heating of the protective element is adjusted when the efficiency value is less than or equal to zero. Procedure according to Claim 4 , characterized in that the heating is set for a predetermined time interval, after which the heating is continued and / or the heating is continued when the at least one environmental parameter changes. Method according to one of the preceding claims, characterized in that the heating output is adjusted when the efficiency value is greater than zero and/or greater than a threshold value. Method according to one of the preceding claims, characterized in that the at least one environmental parameter is a temperature of a vehicle environment and/or a temperature of the protective element (6) and/or a speed of the motor vehicle (1) and/or a blindness value of the radar sensor unit (2). . Method according to one of the preceding claims, characterized in that to determine the respective attenuation value, a signal difference between a radar signal sent by the radar sensor unit (3) and the reflection of the radar signal received by the radar sensor unit (3) is determined. Radar sensor unit (2) for a motor vehicle (1), which is designed to carry out a method according to one of the preceding claims. Motor vehicle (1), which is designed to use a method according to one of the Claims 1 until 8th carry out and / or a radar sensor unit (2). Claim 9 comprises, which is arranged in particular on a vehicle front of the motor vehicle (1).

Images