Radar sensor system for detecting objects, control system for contactlessly adjusting a vehicle flap or vehicle door of a motor vehicle, motor vehicle and method

Abstract

The invention relates to a radar sensor system (1) for detecting objects in a rough detection space (7) and a gesture detection space (8). The radar sensor system can, for example, be arranged on a vehicle (4) in order to adjust a vehicle flap (2) or vehicle door (3) on said vehicle by means of an electric motor (5). The system comprises: a radar sensor arrangement (6), for example consisting of a radar sensor (6a) and an evaluation unit (6b); and a control device (9). The control device (9) is designed to change, depending on the situation, the transmission power for a subsequent actuation of the radar sensor arrangement (6) for emitting radar transmission signals starting from a base value of the transmission power. The invention further relates to a control system, a motor vehicle and a method.

Description

[0001] Radar sensor system for object detection, control system for contactless adjustment of a vehicle flap or vehicle door of a motor vehicle, motor vehicle and method

[0002] The invention relates to a radar sensor system for object detection. The invention also relates to a control system for the contactless adjustment of a vehicle flap or vehicle door of a motor vehicle. Further aspects of the invention include a motor vehicle and a method.

[0003] Radar technology has been known since the early 20th century. It is based on the principle of transmitting electromagnetic waves, receiving the echo of the transmitted electromagnetic waves, and evaluating the received signal according to various criteria as needed. Depending on the specific implementation, various pieces of information about the objects responsible for the reflected echo can be obtained. For example, radar technology can be used to locate an object relative to a radar sensor array, which is possible, among other things, based on distance information. Furthermore, information about the relative motion between the transmitter and the object, the absolute speed of either, or, depending on the design, alternatively or additionally, the object's contours can be obtained, for example, by utilizing the Doppler effect.

[0004] The use of radar is becoming increasingly important, particularly in automotive technology. One reason for this is the desire to increase vehicle autonomy, which has driven the further development of sensors used in vehicles. Radar sensor arrays are now offered as ready-to-install systems for equipping vehicles, for example. In their current state of development, such ready-to-install systems offer a high degree of range and lateral resolution in object detection while requiring minimal installation space. These ready-to-install radar sensor arrays are now available at comparatively low costs, making their use in series production for various applications increasingly attractive.

[0005] For various reasons, not least regulatory ones, ready-to-install radar sensor arrays can operate, for example, in the frequency range between 24 GHz and 81 GHz, with radar sensors operating in the range between 77 GHz and 81 GHz being a commonly used variant. These frequency ranges are sometimes referred to as mmWave in English, due to the wavelength of the emitted electromagnetic waves. Another increasingly common type of radar sensor array is UWB radar modules, which operate with ultra-wideband radar technology. The radar sensor arrays used in the developments described here can, for example, originate from either of the two aforementioned types.

[0006] The use of radar sensors has the advantage that, due to their fundamental operating principle of using the echo of electromagnetic waves to acquire information, they can obtain information that goes beyond what can be achieved with other sensors, such as ultrasonic sensors. Compared to lidar systems, radar sensors have the advantage of being less expensive to acquire. With the increasing use of large numbers of sensors, for example on motor vehicles, the fundamental requirement of ensuring the longest possible operating time for these sensors becomes increasingly important.In this context, the aim is to keep the electricity requirements of the existing radar sensor arrangements as low as possible, without impairing their functionality or at least without impairing it beyond an acceptable or absolutely necessary level.

[0007] The problem is solved by a radar sensor system having the features of claim 1. The problem is further solved by a control system having the features of claim 8, a motor vehicle having the features of claim 10, and a method having the features of claim 11.

[0008] A radar sensor system is provided, which serves to detect objects using radar.

[0009] The radar sensor system includes a radar sensor array for detecting objects. The radar sensor array provides the core functionality of the radar sensor system, namely the transmission of radar signals and the reception of the reflected radar signals, the so-called radar response.

[0010] It could, for example, be a radar sensor arrangement suitable for gesture recognition operating in the frequency range around 24 GHz, for example between 23 and 25 GHz, or in the frequency range around 60 GHz, for example between 59 and 61 GHz, or in the frequency range between 77 GHz and 81 GHz.

[0011] The radar sensor assembly can, for example, be a radar sensor that is commercially available as a compact, ready-to-install module.

[0012] Alternatively, the radar sensor arrangement can be a module-based unit consisting of a radar sensor and an evaluation unit, which is designed, for example, as a microcontroller.

[0013] Furthermore, a control unit is present. The control unit can be part of the radar sensor assembly and, for example, be designed as a microcontroller. However, the control unit can also be a control unit coupled to the radar sensor assembly, for example, part of the central control unit of a vehicle or the central control unit of a vehicle.

[0014] The control unit is configured to drive the radar sensor array to transmit radar signals. Furthermore, the control unit is designed to evaluate the radar response signals generated from the reflection of the radar transmission signals. After evaluating the radar response signals, the control unit can, depending on the result of the evaluation, change the transmission power for the next drive of the radar sensor array to transmit radar signals, starting from a base value.

[0015] The invention therefore provides that the transmission power is adaptively adjusted to the situation prevailing at any given time when the radar transmission signals are emitted. The starting point is a baseline value of the radar transmission power, which may be the transmission power with which the radar sensor arrangement is supplied as standard. This baseline value can, for example, be expertly set such that it leads to sufficient results in typical operating conditions; however, in the event of possible deviations in the operating conditions, which may lead to a deterioration of the received signals, the transmission power is immediately adjusted. The radar transmission power can, for example, be the

[0016] The transmission power of a radar signal can be the so-called pulse power. Alternatively, the radar transmission power can be, for example, the transmission power of the radar signals emitted in a given time period, the so-called average power.

[0017] For example, the evaluation of the radar response signals may include determining a signal-to-noise ratio (SNR) and comparing the determined SNR with a predetermined SNR threshold.

[0018] The SNR is the ratio of the available mean signal power of the radar response signals to the available mean noise power (the integral of the spectral noise power density over the bandwidth), and can be determined, for example, over a given period of time, which may be a value between 0.5 seconds and 1 minute.

[0019] If the SNR threshold is undershot, the radar transmit power can be increased for one or more drives to transmit radar signals. For example, an SNR threshold can be specified, with a value between 4 dB and 50 dB, or a factor between 1.1 and 2, preferably between 1.1 and 1.5, and particularly preferably between 1.1 and 1.3. The radar sensor arrangement transmits a radar transmit signal, receives a radar response signal, and if the radar response signal is found to have an SNR below the SNR threshold, the radar transmit power is increased. Subsequent transmission of radar signals can then take place with the increased radar transmit power. It may be intended that the increase is for a one-time transmission of radar signals.Alternatively, the increase can be implemented for multiple transmissions of radar signals, for example, for a number N of consecutive transmissions, where N is a positive integer, for example, with N between 1 and 20. Alternatively or additionally, the increase in transmission power can be applied for a predetermined period, for example, between 1 second and 2 minutes. The increase in transmission power can, for example, be a multiplication of the baseline transmission power by a factor between 1, 1, and 10, preferably between 1, 2, and 5, whereby, for example, the transmission power can be distributed proportionally among the transmitting antennas involved if more than one transmitting antenna is used.

[0020] According to an advantageous embodiment, the evaluation of the radar response signals may include determining a signal-to-noise ratio (SNR) and comparing the determined SNR with at least two predetermined SNR thresholds, and an increased transmit power is assigned to the highest SNR threshold below which the signal is not reached, for one or more triggers to transmit radar signals. In other words, multiple levels of transmit power increase are provided. For example, a first SNR threshold (SNR1) and a second SNR threshold (SNR2) may be provided, where SNR1 > SNR2, and the first SNR threshold is assigned a transmit power increase by a first increase factor EF1, and the second SNR threshold is assigned a transmit power increase by a second increase factor EF2, where EF1 < EF2.If the threshold SNR1 is undershot, but the threshold SNR2 is not, SNR1 is the highest threshold undershot, so the transmit power is increased by the lower amplification factor EF1. By implementing a multi-stage mechanism for increasing the transmit power based on the respective SNR value, the transmit power is adaptively adjusted according to the environmental conditions present at any given time. This ensures, for example, that in certain cases where there is even a temporary deterioration in the SNR, the radar sensor system continues to function as expected.This allows the radar sensor system to react adaptively to external influences, such as weather-related changes in the transmission and reception situation, for which, for example, snow cover deposited on or in the immediate vicinity of the radar sensor system is just one of many possible examples.

[0021] According to another advantageous embodiment of the radar sensor system, it is provided that a) the evaluation of the radar response signals includes the determination of a signal-to-noise ratio (SNR) and the comparison of the determined SNR with a predetermined SNR threshold, and b) if an SNR threshold is undershot, the radar transmit power is increased by an increase in transmit power for one or more triggers to transmit radar transmit signals.

[0022] Increasing by an increase value can, for example, be an increase by an absolute amount of performance; alternatively, increasing by an increase value can also be an increase by a specific factor.

[0023] Furthermore, steps a) and b) are repeated until either the SNR threshold is no longer undershot or a predetermined maximum transmit power is reached. This means that the transmit power is iteratively adjusted in several steps until a sufficient increase is observed. Alternatively, further increases are omitted if the SNR threshold remains too low and a predetermined maximum transmit power is reached. This iterative increase in transmit power ensures that a sufficiently good SNR ratio is achieved while simultaneously managing the energy required to provide the transmit power efficiently.

[0024] The radar sensor arrangement typically has several antennas, for example 2 transmitting antennas and 3 receiving antennas.

[0025] All the measures described can be implemented, for example, by operating the radar sensor system with exactly one transmitting antenna and exactly one receiving antenna; this could, for example, be an energy-saving mode.

[0026] However, it may also be intended that a majority of the transmitting antennas and / or a majority of the receiving antennas are used, in particular all antennas of the radar sensor arrangement.

[0027] The measures described can then be implemented in such a way that they apply to exactly one specific antenna with regard to the receiving antennas, or apply to at least one of the existing antennas, or apply to the entire antenna system.

[0028] For example, it may be provided that if the SNR threshold is undershot with the signal at a predetermined antenna of the existing receiving antennas, which is used as a reference antenna, an increase in the radar transmit power is carried out for one or more drives to transmit radar transmit signals.

[0029] For example, it may be provided that if the SNR threshold is undershot with the signal at at least one of the available receiving antennas, an increase in the radar transmit power is carried out for one or more control points to transmit radar transmit signals.

[0030] For example, it may be provided that if the SNR threshold is undershot at all available receiving antennas, the radar transmit power is increased for one or more transmitters to send radar transmit signals; in other words: an increase is only carried out if the SNR threshold is not undershot at any of the available receiving antennas.

[0031] Furthermore, the described measures can be implemented in such a way that they affect all transmitting antennas in use, for example, in energy-saving mode for exactly one transmitting antenna, or for all existing transmitting antennas. For example, the increase in transmit power can be distributed evenly across all transmitted antennas in use or across all existing transmitting antennas, so that, for example, with three existing transmitting antennas, the power increase is distributed equally, with one-third going to each of the transmitting antennas.

[0032] According to an advantageous further development of the radar sensor system, the transmission power is increased for a predetermined period and then reset to its base value. This procedure ensures that the increase in transmission power is initially only temporary, which avoids unnecessary energy consumption, particularly when the insufficient quality of the radar response signals is the result of another temporary event, such as reflection of only a very small proportion of the transmitted radar signals when the radar sensor array is radiating into a poorly reflective environment.

[0033] It is also possible that the increase in transmission power refers to the pulse power, or that the increase in transmission power refers to the average power.

[0034] A particularly preferred embodiment of the radar sensor system may, for example, provide that the control unit is configured to output a calibration radar transmit signal in order to receive calibration radar response signals. The baseline value is then set based on these calibration radar response signals. Thus, the control unit provides a means for calibrating the radar sensor system by setting a baseline value of a deemed necessary magnitude based on the expected quality of the calibration radar signals. Specifically, the control unit may store a number of baseline values, with each baseline value corresponding to a range of signal-to-noise ratios (SNR) of the calibration radar response signal.Based on this, after receiving a calibration radar response signal, its signal-to-noise ratio (SNR) can be determined, and a base value assigned to this SNR can be used for the basic operation of the radar sensor array. The advantage of this approach is that, in addition to adaptively adjusting the transmission power of the radar signals depending on temporarily prevailing environmental conditions, it allows the radar sensor system to be designed for operation under permanently prevailing environmental conditions.For example, it is possible to offer a radar sensor system for installation in a wide variety of application environments and to ensure its proper functioning at all times by permanently setting the base level of the radar transmit power after installation in a specific application environment, thanks to the described provision of the calibration radar transmit signal and the base value assigned to a signal-to-noise ratio (SNR) of the calibration radar response signals. This approach is particularly successful when calibration is performed in a predefined reference environment, such as one specified by the radar sensor system supplier.

[0035] It is particularly desirable for the control unit to be configured to set the base value once and then retain it immutably. This can be achieved, for example, by storing the data in a WORM file system (Write-Once-Read-Only file system) or simply by appropriately programming the control unit. This approach ensures that the radar sensor system is professionally configured by a system provider, such as an OEM in the automotive sector, and can then be used by an end user without any further interference with its fundamental functionality.

[0036] Another aspect of the invention relates to a control system. The control system is designed for the contactless adjustment of a vehicle flap or vehicle door of a motor vehicle. The control system includes an electric motor coupled to the vehicle flap or vehicle door in order to enable contactless automatic adjustment of the vehicle flap or vehicle door.

[0037] The control system comprises a radar sensor system according to the invention or one of its further developments, and thus also includes a radar sensor arrangement and a control device coupled to the radar sensor arrangement.

[0038] Coupled with the radar sensor arrangement and the electric motor is a control device, which may be, for example, the control unit of the radar sensor system or another control device designed to cause the adjustment of the vehicle flap or vehicle door by means of the electric motor, depending on a control gesture performed within a gesture detection area and detected by the radar sensor arrangement in a gesture detection mode.

[0039] The evaluation of the control gesture can take place, for example, in a vehicle-side control device, such as a central control unit or the aforementioned control unit of the radar sensor system, or - if present - by the further control unit.

[0040] According to the invention, the radar sensor arrangement can assume at least two operating modes: a gesture detection mode and an energy-saving mode. The energy-saving mode is a mode that, compared to the gesture detection mode, exhibits reduced energy consumption by the radar sensor arrangement. This is achieved by accepting a reduction, for example, in the spatial and / or temporal resolution of the radar detection. For example, the radar sensor arrangement can be a radar sensor or comprise a radar sensor with a plurality of transmitting antennas and a plurality of receiving antennas. The energy-saving mode provides for the measure that, unlike the gesture detection mode, only a subset of the available transmitting antennas and / or a subset of the available receiving antennas are activated, which results in the desired reduced energy consumption.

[0041] Even in energy-saving mode, it is advisable to implement the described increase in transmission power if the detected signal-to-noise ratio is too low, since the increased transmission power does lead to a higher energy requirement during signal transmission, but in return, due to the higher data quality, evaluation with lower-order filters can be expected to be sufficient, along with less energy-intensive calculations.

[0042] According to the invention, the radar sensor arrangement is configured to switch from energy-saving mode to gesture detection mode depending on radar responses detected in energy-saving mode from a coarse detection area, i.e., a radar response resulting from the reflection of emitted radar signals back to the radar sensor arrangement in the coarse detection area. The inventive design of the radar sensor arrangement thus provides for two different types of detection in two operating modes: gesture detection in the regular mode and a less demanding detection method compared to gesture detection, for example, with regard to temporal and / or spatial resolution, which is particularly associated with lower energy consumption and is therefore suitable as an energy-saving mode.In the example above, where only a subset of the available transmitting antennas and / or a subset of the available receiving antennas are used for object detection, gesture recognition in gesture detection mode is no longer possible or only possible with reduced accuracy. However, the radar sensor array receives a radar response that differs from that of an object-free area when an object enters the coarse detection area, and can infer the entry of an object into the coarse detection area from this response. Alternatively or additionally, it can also be provided that a smaller bandwidth of the transmit frequencies is used in energy-saving mode, which makes the evaluation of the radar response less complex and thus improves energy efficiency.Preferably, in energy-saving mode only one transmitting antenna and one receiving antenna are activated, but with a higher transmit power than is available to either antenna in gesture recognition mode, so that the total transmit power is lower in energy-saving mode, but the transmit range is higher in energy-saving mode, which benefits the idea of ​​initial detection of an approach in energy-saving mode.

[0043] In particular, it can be provided that the coarse detection mode has a greater range from the vehicle than the gesture detection range. This can be achieved, for example, by a higher transmission power, which is used, in particular, to drive one of the transmitting antennas of the radar sensor arrangement for the emission of a radar signal in the coarse detection mode, in order to promote energy savings. The emission parameters in the coarse detection mode are therefore designed by those skilled in the art for long range with low energy consumption, whereby the energy consumption is reduced by the emission of radar signals at comparatively long time intervals, for example, at intervals between 1 second and 600 seconds, preferably between 5 seconds and 100 seconds.It may also be possible for the time intervals to be dependent on the time of day, so that, for example, longer intervals are scheduled at night than during the day, since there is less frequent need to access the vehicle at night. Finally, it may be possible to allow the user to change the time-dependent intervals via a user setting.

[0044] By default, the radar sensor array is in power-saving mode to limit higher energy consumption to periods when gesture detection is required or when a gesture is expected to be performed at an increased probability. To enable the radar sensor array to switch advantageously from power-saving mode to gesture detection mode at appropriate times, it is configured to detect movement of an object within a coarse detection area while in power-saving mode and to enter gesture detection mode in response to the detected movement.

[0045] It is therefore specifically intended that a combination of an energy-saving mode with an adjustable transmission power is combined, thereby advantageously achieving a particularly good saving of energy.

[0046] In one implementation, it may be provided that a pattern recognition of the detected movement is carried out, and the activation from the energy saving mode to the gesture recognition mode is carried out depending on the result of the pattern recognition.

[0047] In gesture recognition mode, a gesture performed within the gesture recognition area is recorded and then evaluated to determine whether it is a gesture intended for control. If so, the adjustment of the

[0048] caused by the vehicle door or the vehicle hatch.

[0049] Radar sensor arrangements can, for example, be located in the immediate vicinity

[0050] Upon receiving a detected control gesture, the system can re-enter energy-saving mode. Alternatively or additionally, it can be provided that the radar sensor arrangement returns to energy-saving mode after a predetermined period, which can be, for example, a value between 10 seconds and 60 minutes, preferably between 1 minute and 30 minutes, and most preferably between 5 minutes and 20 minutes, without a detected control gesture.

[0051] In a further training program, it may be stipulated that a switch to active mode does not occur in every instance of movement detected in energy-saving mode, but rather that the switch to active mode requires pattern recognition indicating a reason to do so. The concept of pattern recognition specifically encompasses checking whether the motion data captured by the radar sensor response meets predefined conditions. Pattern recognition can be performed, for example, in a vehicle-side control device, such as a central control unit or the aforementioned control unit. If the radar sensor assembly is a module consisting of a radar sensor and an evaluation unit, such as a microcontroller, pattern recognition can be performed within the microcontroller itself.

[0052] A significant advantage of performing pattern recognition before switching to active mode is that the number of false triggers, i.e., activations into gesture recognition mode without a subsequent sender to be recorded or gesture to be evaluated, can be reduced.

[0053] Depending on the current operational situation of a vehicle, activation in gesture recognition mode is possible.

[0054] Dependence on radar responses detected in coarse detection mode with varying degrees of reliability is possible. For example, situations may arise in which an object's approach into the coarse detection area is detected very frequently, but due to the specific circumstances—contrary to the assumption described above—this is a special situation in which no control action should be taken in response to the detected approach of an object, and therefore gesture recognition of a control gesture is not required. These are situations in which objects frequently enter the vehicle's coarse detection area that are not the vehicle's regular operator.

[0055] An example of such a situation is a motor vehicle parked in a dense crowd. The dense crowd would frequently trigger the detection of an object approaching, particularly a person, within the radar's detection range. However, unlike in typical scenarios, the majority of these approaches result from people simply passing by without any actual control action, such as opening or closing a vehicle door. Therefore, in many cases, the radar sensor array would be activated without any control action being required; this is a false alarm.The false triggering of the radar sensor arrangement's activation is an activation of the radar sensor arrangement that is not followed by a gesture detection, in other words, no gesture detection occurs within a period of time that may be, for example, 5 seconds after activation, or 120 seconds after activation, or a period of time that lies between the two aforementioned values.

[0056] The radar sensor arrangement is particularly preferably configured to distinguish, by means of pattern recognition, between a movement of the operator indicating that the operator is approaching the vehicle and a movement of the operator that does not indicate that the operator is approaching the vehicle. Only when the pattern recognition detects a movement indicating that the operator is approaching is the activation switch performed from energy-saving mode to gesture detection mode. It can be provided that, upon detection of a movement indicating that the operator is approaching, the activation switch is performed immediately in response, meaning that the detection of approach is a sufficient condition for triggering the activation switch.However, it can also be stipulated that the detection of the approach is a necessary condition, and that the activation only occurs if one or more further conditions are confirmed as fulfilled.

[0057] Pattern recognition can, for example, include the evaluation of a motion's trajectory. For instance, it may be provided that a motion trajectory detected by the radar sensor array is recorded and evaluated for a specific period. For example, the evaluation of the motion trajectory by the radar sensor array or the evaluation device coupled to it, such as the control device, a central control unit, or the aforementioned control unit, can be interpreted as indicating an approach by the operator if a motion vector describing the motion trajectory was directed towards the radar sensor array for the entire specified period or was detected deviating from it by no more than a maximum angle of deviation.

[0058] Alternatively or additionally, the pattern recognition may include or consist of an evaluation of the object's dimensions. For example, the evaluation may be interpreted as indicating an approach by the operator if the object's dimensions are within typical human dimensions. Additionally or alternatively, it may be provided that an approach by the operator is ruled out if the dimensions are not within typical human dimensions. For example, an approach by the operator may be ruled out if the object is smaller than 50 cm, thus potentially indicating the approach of a fox or cat, which would not require activation of the radar sensor array.

[0059] Alternatively or additionally, pattern recognition can include or consist of the detection of periodic changes. For example, the detection of periodic movements can rule out the possibility that the movement is caused by an approaching operator. This ensures, for instance, that periodic movements such as leaves moving in the wind are not misinterpreted as an approaching operator.

[0060] Alternatively or additionally, the pattern recognition may involve the evaluation of several detected objects, or consist of evaluating several detected objects. For example, if more than one object of approximately equal size is detected, an approach by the operator may be assumed not to be present. This may be based, for instance, on the assumption that in such a situation the vehicle is located in a crowd or a group of several objects, and that in such a situation an operator action is not expected, or at least less likely than it would appear based on the initial coarse detection.

[0061] Alternatively or additionally, the pattern recognition may include the evaluation of a time-dependent and / or day-dependent movement of the object, or consist of such an evaluation. For example, the detection of an operator's approach during the day may be based on different assumptions than at night.

[0062] Alternatively or additionally, the pattern recognition can include evaluating the object for features that distinguish it as a human from an animal and / or a non-living object. For example, the radar sensor array can differentiate between the heart rate of a human and that of an animal by evaluating the heart rate of an approaching living being. A heart rate above 100, for instance, can be used to assume that an animal, such as a dog or cat, is approaching, and in this case, the radar sensor array should not be activated.

[0063] The measures mentioned above have the advantage of increasing the likelihood that the radar sensor array will be activated in cases where a control gesture is expected.

[0064] In a special case, pattern recognition can consist of exactly one of the aforementioned evaluation variants, meaning that no supplementary evaluations take place. In particular, it can be stipulated that a movement is considered an approach if the pattern recognition does not rule out the possibility of an approach.

[0065] According to a further development, it is provided that the change in transmission power depending on the radar response signals, i.e., depending on an SNR value, is deactivated when the gesture recognition mode is activated. This is based on the consideration that, in a case where it has already been recognized that gesture recognition is required, the person skilled in the art implementing the invention will select the transmission power of the radar sensor arrangement at a level high enough to ensure sufficiently good signal recognition in every case.This consideration, in turn, is based on the premise that optimizing the energy required for the relatively infrequent and short periods of gesture recognition does not play a significant role in the overall energy balance, but rather that such considerations aimed at optimizing energy demand can be limited to the periods of energy saving or that constitute the majority of the time.

[0066] Another component of the present considerations concerns a motor vehicle that has a vehicle hatch and / or a vehicle door and is also equipped with a control system of the type described above.

[0067] Another aspect of the invention relates to a method in which a control system of the type described above is installed in a motor vehicle.

[0068] The process includes the following steps:

[0069] - Arranging the radar sensor array at an installation position,

[0070] - Initiating a calibration process, where the

[0071] The radar sensor array outputs a calibration radar transmit signal and receives the calibration radar response signals, - determining a signal-to-noise ratio (SNR) of the

[0072] Calibration radar response signals

[0073] - Setting a baseline value for the transmission power of radar signals. This setting is based on the signal-to-noise ratio (SNR) and on a reference table stored on a storage medium of the radar sensor assembly or the control unit, or on a storage medium coupled to the radar sensor assembly or the control unit. This reference table assigns a baseline transmission power value to each SNR. The method is based on the consideration that the installation situation of a control system according to the invention and its further developments is subject to variations depending on the specific application. For example, the power at which radar signals are transmitted is subject to attenuation effects in radar sensors that are, for example, arranged under a car's bumper. The extent of these attenuation effects, in turn, depends, for example, on the material and its thickness.The method according to the invention serves not only to bring about adaptive adjustment to fluctuating environmental situations in a radar sensor system, but also to provide an optimized basic level of transmission power.

[0074] Further details, features and advantages of the control system according to the invention will become apparent from the following description in conjunction with the figures, in which an exemplary embodiment of the invention is shown.

[0075] It is understood that the features mentioned above, as well as those explained below, can be used not only in the combinations specified, but also in other combinations or individually. Figure 1 shows an exemplary embodiment of a control system with a radar sensor system according to the invention.

[0076] Fig. 2: Control system from Fig. 1 with shaded radar sensor arrangement;

[0077] Fig. 3: Control system from Fig. 1 with more heavily shaded radar sensor arrangement.

[0078] Figure 1 shows an exemplary embodiment of a control system 1. The control system 1 serves to adjust a vehicle flap 2 or vehicle door 3 of a motor vehicle 4 without physical contact. In Figure 1, this is illustrated using the example of the vehicle flap 2 designed as a trunk lid.

[0079] Vehicle 4 is equipped with an electric motor 5, which is coupled to the vehicle flap 4 designed as a trunk flap.

[0080] Furthermore, a radar sensor arrangement 6 for detecting objects is arranged on the vehicle 4. In the illustrated embodiment, the radar sensor arrangement 6 is designed as a compact assembly consisting of a radar sensor 6a and an evaluation unit 6b coupled to the radar sensor 6a. The radar sensor 6a and the control unit designed as an evaluation unit 6b, together with the specific configuration of the microcontroller, form a radar sensor system according to the invention. In the illustration shown, the orientation of the transmitting and receiving antennas (not shown in the illustration) in the radar sensor 6a is such that gesture detection in gesture detection mode is possible when the gesture takes place within the gesture detection area 8.In gesture detection mode, the radar sensor 6a operates at its full temporal and spatial resolution, for which the operation of most or all of the transmitting and receiving antennas present in the radar sensor 6a is particularly important. This enables the best possible detection of a kicking movement, which is a prerequisite for evaluating the course of the kicking movement and consequently for deciding whether an output signal is issued depending on a detected gesture executed as a kicking movement. Coupled with the radar sensor arrangement 6 and the electric motor 5 is a control unit 9, which can be a dedicated opening control unit or alternatively can be provided by the central vehicle control unit.The control unit 9 is configured to recognize an output signal issued according to the above explanation, depending on the control gesture performed within the gesture detection area 8 and detected by the radar sensor arrangement 6 in gesture detection mode. When the control unit 9 recognizes the output signal, it initiates the adjustment of the vehicle flap as a result of receiving the output signal, for example, opening or closing the vehicle flap, which is then carried out by means of the electric motor 5.

[0081] To minimize the energy consumption of the control system 1, the radar sensor arrangement 6 has at least two operating modes. In addition to the gesture recognition mode, the control system 1 has an energy-saving mode. For example, the radar sensor 6a contained in the radar sensor arrangement 6 can have a plurality of transmitting antennas and a plurality of receiving antennas, which is advantageous for time- and location-resolved data acquisition and is standard practice for commercially available radar sensors. In such a radar sensor 6a, the energy-saving mode can, for example, provide that only a subset of the available transmitting and receiving antennas is activated, preferably exactly one transmitting antenna and exactly one receiving antenna.This significantly reduces the overall system's energy consumption. However, for coarse detection to gather information about an approaching object—for example, a potential operator approaching with the intention of triggering a flap adjustment—operation of only a subset of antennas is sufficient, provided the radar sensor array is positioned appropriately, a position easily achievable by a technician through simple trial and error. Alternatively or additionally, the energy-saving mode can be implemented by transmitting radar signals significantly less frequently in a given time unit than in gesture detection mode, switching to a higher number of transmitted radar signals only when gesture detection mode is activated. It is also possible to provide a reduced transmission frequency bandwidth in energy-saving mode compared to gesture detection mode.By using one or more of the aforementioned measures, and with expert adjustment of the parameters, it is possible to achieve an energy-saving mode with low energy consumption without accepting unacceptable levels of comfort.

[0082] The radar sensor array 6 is switched to a power-saving mode in situations where gesture recognition is less likely to be required. This power-saving mode can be the default mode, as it can be assumed that periods requiring flap adjustment represent only a small fraction of the total operating time.

[0083] From energy-saving mode, the radar sensor array 6 can be switched to gesture detection mode. This switchover occurs depending on the radar responses detected in energy-saving mode from a coarse detection area 7. Thus, even in energy-saving mode, the environment is continuously or intermittently detected with radar waves at certain regular or irregular intervals. This is achieved by repeatedly emitting radar signals and receiving the reflected radar waves, i.e., the radar response.This radar monitoring in energy-saving mode can be performed with a reduced number of antennas, for example, exactly one transmitting antenna and one receiving antenna. In addition, a radar survey of the surroundings can be performed with a reduced frequency of repetitions per unit of time, for example, with a repetition frequency of up to 5 queries per second or even lower, from 1 query per second or even significantly less, such as 1 query every 10 seconds or one query per unit of time, which is between 1 second and 60 seconds.

[0084] The radar sensor arrangement 6 is also configured to be activated in gesture detection mode after and in response to the detection of movement of an object in the coarse detection area 7. For example, pattern recognition may be performed before activation. This may stipulate, for instance, that an approach by the operator is considered impossible if the operator's dimensions, as derived from the radar response, are not within typical human dimensions, and that otherwise, an approach is assumed. Only in the latter case is an approach assumed, and the gesture detection mode is activated. In one implementation, this activation occurs immediately; in another, activation occurs only upon fulfillment of further conditions.

[0085] The radar sensor system, consisting of radar sensor 6a and the control unit 6b (designed as an evaluation unit) with its specific programming, serves to detect objects. The control unit is configured to drive the radar sensor array to transmit radar signals and to evaluate the radar response signals generated from the reflection of these signals. The evaluation of the radar response signals includes determining the signal-to-noise ratio (SNR) and comparing the determined SNR with a predefined SNR threshold. The signal and the underlying noise are symbolically represented in the graph St. The transmit power Ptx, with which radar signals are emitted, is Pbasis.

[0086] In Fig. 2, the radar sensor is lightly covered, for example with dirt 10 or snow 10. The covering causes the noise of the received radar response signals to increase, and analogously the SNR to decrease. Due to the SNR falling below a certain threshold, the radar transmit power is increased to the value PI, which can be set, for example, for one or more activations to transmit radar signals, alternatively or additionally for a predetermined period.

[0087] Figure 3 shows that the noise has increased due to greater accumulation of dirt 10 or snow 10; as a result of the further reduction of the SNR, a further SNR threshold was undercut and consequently the transmit power was further increased, namely to the value P2 .

Claims

Patent claims 1. Radar sensor system for object detection, comprising a radar sensor arrangement (6) for object detection, a control device (9) which is part of the radar sensor arrangement, or a control device (9) coupled to the radar sensor arrangement (6), wherein the control device is configured to control the radar sensor arrangement (6) to emit radar transmission signals, and to perform an evaluation of the radar response signals generated from the reflection of the radar transmission signals, and after the evaluation of the radar response signals, to change a transmission power for a next control of the radar sensor arrangement to emit radar transmission signals starting from a base value of the transmission power, depending on a result of the evaluation.

2. Radar sensor system according to claim 1, wherein the evaluation of the radar response signals comprises the determination of a signal-to-noise ratio (SNR) and the comparison of the determined SNR with a predetermined SNR threshold, wherein, if an SNR threshold is undershot, the radar transmit power is increased for one or more drives to transmit radar transmit signals.

3. Radar sensor system according to claim 1 or claim 2, wherein the evaluation of the radar response signals comprises the determination of a signal-to-noise ratio (SNR) and the comparison of the determined SNR with a number of at least two predetermined SNR thresholds, and wherein an increased SNR is assigned to the highest SNR threshold that is not reached. Transmit power is provided for one or more control units for transmitting radar signals.

4. Radar sensor system according to claim 1 or claim 2, wherein a) the evaluation of the radar response signals comprises determining a signal-to-noise ratio (SNR) and comparing the determined SNR with a predetermined SNR threshold, b) wherein, if an SNR threshold is undershot, the radar transmit power is increased by an increase in transmit power for one or more triggers to transmit radar transmit signals, wherein steps a) and b) are repeated until either no further undershooting of the SNR threshold is detected or until a predetermined maximum value of a transmit power has been reached.

5. Radar sensor system according to one of the preceding claims, wherein the transmission power is increased for a predetermined period, and afterwards the transmission power is reset to the base value.

6. Radar sensor system according to one of the preceding claims, wherein the control device is configured to output a calibration radar transmit signal in order to receive calibration radar response signals, wherein the base value is set on the basis of the calibration radar response signals.

7. Radar sensor system according to one of the preceding Claims, wherein the control device is set up, the To set the base value once and then keep it unchanged.

8. Control system (1) for contactless adjustment of a vehicle flap (2) or vehicle door (3) of a motor vehicle (4), comprising an electric motor (5) coupled to the vehicle flap (2) or vehicle door (3) for adjusting the vehicle flap (2) or vehicle door (3), a radar sensor system according to one of the preceding claims for detecting objects with the radar sensor arrangement arranged in the area of ​​the vehicle flap (2) or vehicle door (3), for detecting a control gesture to be performed by an operator, a control means (9) coupled to the radar sensor arrangement (6) and the electric motor (5), wherein the control means (9) is configured to cause the adjustment of the vehicle flap (2) or vehicle door (3) by means of the electric motor (5) depending on a control gesture performed within a gesture detection area (8) and recognized by the radar sensor arrangement (6) in a gesture detection mode,wherein the radar sensor arrangement (6) can assume at least two operating modes, namely the gesture detection mode and an energy-saving mode, wherein the radar sensor arrangement (6) is configured to activate from the energy-saving mode into the gesture detection mode, in the energy-saving mode to detect a movement of an object taking place in a coarse detection area (7), and in response to the detected movement of the object, To activate the device from energy saving mode to gesture recognition mode.

9. Control system ( 1 ) according to claim 8, wherein the change in transmission power is deactivated when switching to gesture detection mode.

10. Motor vehicle ( 4 ) comprising a vehicle hatch ( 2 ) and / or a vehicle door ( 3 ) as well as a control system ( 1 ) according to claim 8 or according to claim 9 .

11. Method for installing a control system according to claim 8 or claim 9 in a motor vehicle, comprising the steps of: - Arranging the radar sensor array at an installation position, - Initiating a calibration process, wherein the radar sensor array outputs a calibration radar transmit signal and receives the calibration radar response signals, - Determining the signal-to-noise ratio (SNR) of the calibration radar response signals, - Establishing a base value for the transmission power of radar signals based on the SNR using a reference table stored on a storage medium of the radar sensor assembly or control unit, or on a storage medium coupled to the radar sensor assembly or control unit.

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