DE102020204381B4 - Method for operating a radar system and radar system - Google Patents

Abstract

Method for operating a radar system (10), wherein the radar system (10) has at least two radar sensors (20-1, 20-2) for a respective object detection by transmitting a radar signal (TX), receiving a radar signal (RX) reflected on an object, and evaluating the received radar signal (RX), and wherein the method provides a detection operating mode in which the at least two radar sensors (20-1, 20-2) are operated to detect objects, wherein the method also provides a data transmission mode, having the following steps: - Transmission of a based on a data signal (c4) modulated radar signal (TXD) by a first radar sensor (20-1) of the at least two radar sensors (20-1, 20-2), - Receiving of the first radar sensor (20-1) sent Radar signal (TXD) by a second radar sensor (20-2) of the at least two radar sensors (20-1, 20-2), and evaluating the radar signal (TXD) received from the second radar sensor (20-2) in order to use the data sign al (c4), and wherein in data transmission mode the first radar sensor (20-1) transmits at a predetermined time-varying radar signal transmission frequency and the second radar sensor (20-2) receives at a fixed predetermined radar signal reception frequency, so that at least one point in time during this variation, the radar signal transmission frequency of the first radar sensor (20-1) corresponds to the radar signal reception frequency of the second radar sensor (20-2), orwherein in data transmission mode the first radar sensor (20-1) transmits at a fixed predetermined rate Radar signal transmission frequency (fTXD) and the second radar sensor (20-2) is received with a predetermined time-varying radar signal reception frequency (fLO), so that at least one point in time during this variation, the radar signal reception frequency (fLO) of the second radar sensor (20-2) corresponds to the radar signal transmission frequency (fTXD) of the first radar sensor (20-1).

Description

The present invention relates to a method for operating a radar system according to the preamble of claim 1 and a radar system according to the preamble of claim 6.

Such a method for operating the radar system provides a detection operating mode in which a plurality of radar sensors of the radar system can be operated to detect objects, with a respective object detection being accomplished by transmitting a radar signal, receiving a radar signal reflected on an object, and evaluating the received radar signal.

The use of radar sensors is becoming increasingly important in many areas of application, be it in stationary applications such as e.g. B. in business and household (motion detectors, surveillance technology, etc.), or, for example, in automotive engineering, such as radar systems with radar sensors for determining distance (parking aid, distance cruise control, etc.) and / or radar sensors for automatic door opening systems.

The arrangement of at least two or more radar sensors on a relevant technical facility (building, device, vehicle, inductive charging arrangement for vehicles, etc.) has the advantage that isolated object detection is made possible for several spatially separate or non-identical detection areas of the individual radar sensors . In addition, several radar sensors can also be advantageous or necessary in order to be able to cover a larger detection area and/or a detection area surrounding the technical device (e.g. 360° surroundings of a vehicle) when detecting objects.

In a vehicle with one or more automatically or motor-operated doors with a radar system for detecting any obstacles, at least one radar sensor per door can be used, for example, in order to reliably initiate or assist automatic door opening (and/or door closing) processes by detecting the respective object to disable or stop door opening (or door closing) if there is an obstacle detected by object detection, or e.g. B. to realize an adjustment of the door just before the obstacle.

WO 2018/ 222 268 A1 discloses techniques and devices that enable radar modulations for radar detection using a wireless communication chipset. A controller initiates or controls modulations performed by the wireless communication chipset. In this way, the controller can enable the wireless communication chipset to perform modulations for wireless communication or radar detection.

P. Barrenechea, F. Elferink and J. Janssen: FMCW radar with broadband communication capability, 2007 European Radar Conference, Munich, 2007, page 130-133 discloses an FMCW radar system with amplitude modulation.

DE 10 2018 124 413 A1 discloses an inductive charging system for motor vehicles with a radar sensor.

It is an object of the present invention to increase the usefulness in the operation of a radar system of the type mentioned at the outset, in order thus, for example, to expand the area of application of such a radar system.

• - Senden eines basierend auf einem Datensignal modulierten Radarsignals durch einen ersten Radarsensor der wenigstens zwei Radarsensoren,
• - Empfangen des vom ersten Radarsensor gesendeten Radarsignals durch einen zweiten Radarsensor der wenigstens zwei Radarsensoren, und
• - Auswerten des vom zweiten Radarsensor empfangenen Radarsignals, um damit das Datensignal zurückzugewinnen.

According to a first aspect of the present invention, this object is achieved in a method of the type mentioned at the outset in that the method also provides a data transmission mode, having the following steps:

• - Transmission of a radar signal modulated based on a data signal by a first radar sensor of the at least two radar sensors,
• - Receiving the radar signal transmitted by the first radar sensor by a second radar sensor of the at least two radar sensors, and
• - Evaluation of the radar signal received from the second radar sensor in order to recover the data signal.

With the invention, data can advantageously be transmitted from the first radar sensor to the second radar sensor. In practice, this additional functionality usually does not require any significant additional hardware expenditure.

The terms "first" radar sensor and "second" radar sensor used here are only to be understood with regard to the use of (at least) two radar sensors to implement the data transmission mode and their respective purpose in the context of data transmission (the "first radar sensor" transmits the " second radar sensor "receives).

It follows from this that, with the invention, in particular bidirectional communication (data transmission) can also be implemented between the (at least) two radar sensors of the radar system. In this case, the two radar sensors in question are required depending on the moment Data transmission direction used either as "first" and "second" radar sensor, or vice versa as "second" and "first" radar sensor.

If the radar system z. B. has two or three radar sensors, so z. B. be provided that each of these two or three sensors can be used in data transmission mode as the first radar sensor. In a preferred embodiment, however, only a single radar sensor is operated as the first radar sensor at any given time. In principle, however, each of the two or three sensors can also be used as the second radar sensor (unless already being used as the first radar sensor at the same time). If the radar system has more than two radar sensors, then in principle unidirectional or bidirectional data transmission connections can be implemented with the invention for any pairs of these radar sensors.

The benefit of the data transmission link implemented according to the invention in a radar system can be used in practice e.g. B. consist of at least one or z. B. form exactly one of the radar sensors with relatively high data processing power (“computing power”) and (at least) one (or more) of the radar sensors with, in contrast, lower data processing power (and thus cheaper), with the latter or the latter radar sensors z. B. from the object detection data can be transmitted for further processing to the or a more powerful radar sensor.

A further use of the data transmission connection implemented according to the invention can e.g. B. consist in bringing about or improving a synchronization between different radar sensors that is advantageous or even necessary for the operation of the radar system, by data being transmitted for such a synchronization.

Furthermore, the data transmission connection can also be useful for radar sensors that (e.g. in a vehicle) are already communicatively connected to one another via a digital communication bus system (e.g. CAN bus, LIN bus, etc.), because the communication bus system can be relieved. In modern vehicles, such communication bus systems are often used to near their performance limits, so that with the invention z. B. In particular for particularly time-critical communications (“real-time data exchange”), an advantageously additionally usable transmission path is created.

The data transmission implemented according to the invention in the data transmission mode runs via a “transmission path” from the first radar sensor to the second radar sensor.

In a preferred embodiment, a radar system is used in which such a transmission path is already created by the radar system as such or by the installation environment of the radar system (technical device such as a vehicle) as such. In this case, a transmission path advantageously exists regardless of whether there are any objects in the detection range of the radar system or not.

According to a simple embodiment, a radar system is used in which there is (at least) one transmission path through a (straight) "direct line of sight" between the relevant radar sensors, which enables the radar signal to be transmitted from the first radar sensor to the second radar sensor. In this case, the line of sight represents the shortest connection between the relevant radar sensors.

A direct line of sight between the two radar sensors used in data transmission mode can in practice z. B. be ensured by using so-called side lobes of the relevant antenna characteristics. In a corresponding embodiment, the first and second radar sensors z. B. arranged offset from one another in the lateral direction with at least approximately parallel main directions or main lobes of the antenna characteristics, with the main lobes primarily being used in the detection operating mode. It can then turn out that in the data transmission mode z. B. primarily or exclusively the side lobes of the antenna characteristics are used.

According to another embodiment variant, a radar system is used in which there is no direct line of sight between the two radar sensors in question for at least one transmission path, but the radar system or its installation environment still ensures due to the design that the radar signal transmission via this transmission path from the first radar sensor is enabled via one or more radar signal reflections up to the second radar sensor. This also advantageously creates a transmission path that is independent of the presence of any objects in the detection range of the radar system.

To create such an indirect line of sight, esp special bumpers and/or side mirrors are used as (parasitic) reflection objects. As an alternative or in addition, the vehicle can have add-on parts arranged specifically for this purpose. Each of such reflection objects can increase the radar cross section and thus reflectivity z. B. be provided with a metallization layer.

• - Senden eines Radarsignals durch einen ersten Radarsensor der wenigstens zwei Radarsensoren,
• - Empfangen des vom ersten Radarsensor gesendeten Radarsignals durch einen zweiten Radarsensor der wenigstens zwei Radarsensoren, und
• - Auswerten des vom zweiten Radarsensor empfangenen Radarsignals, um damit zu diagnostizieren, ob eine Radarsignalübertragung über einen vom ersten Radarsensor zum zweiten Radarsensor verlaufenden Übertragungspfad funktioniert oder ob dieser Übertragungspfad beeinträchtigt ist.

In a development of the invention, it is provided that the method also provides a diagnostic operating mode, having the following steps:

• - Transmission of a radar signal by a first radar sensor of the at least two radar sensors,
• - Receiving the radar signal transmitted by the first radar sensor by a second radar sensor of the at least two radar sensors, and
• - Evaluation of the radar signal received from the second radar sensor in order to diagnose whether a radar signal transmission works via a transmission path running from the first radar sensor to the second radar sensor or whether this transmission path is impaired.

The radar signal transmitted according to this development can be, for. B. to act according to the invention anyway provided, based on a data signal modulated radar signal. In this case, the evaluation of the radar signal received from the second radar sensor would not only serve to recover the data signal, but also to diagnose the transmission path. In other words, it is not excluded that a data transmission mode and a diagnostic operating mode can take place at the same time. However, a radar system is also possible in which, as an alternative or in addition to carrying out the diagnosis during a data transmission mode, such a diagnosis takes place at other points in time (or independently of the data transmission).

If in the diagnostic operating mode, whether during or separately from a data transmission mode, the evaluation of the radar signal received from the second radar sensor (e.g. by assessing the radar signal intensity and/or other properties of the radar signal) shows that the radar signal transmission from the first radar sensor to the second radar sensor is working and thus the transmission path is not impaired, the error case of an occupancy of one or both radar sensors (e.g. with snow, ice, rainwater, dirt, etc.) can advantageously be ruled out.

If, however, the evaluation of the radar signal received by the second radar sensor shows that the transmission path is not functioning properly and is therefore impaired, then improper operability of the radar system is diagnosed.

The improper function can e.g. B. be diagnosed based on a determination of an excessively reduced (z. B. below a predetermined threshold) radar signal intensity. If a diagnostic operating mode is carried out during a data transmission mode, the improper function can alternatively or additionally z. B. can be diagnosed on the basis of an evaluation of a data error rate at the receiving end, in that the transmission path is judged to be impaired when the error rate (e.g., bit error rate, for example, is above a predetermined threshold) is excessively high. An error rate can e.g. B. be determined as part of an error correction process carried out at the receiving end.

The aforementioned development advantageously enables a “free-to-air” diagnosis of a radar system in the sense of checking whether its radar sensors can transmit (emit) and receive unhindered. This can e.g. B. the error can be detected, which is caused by an occupancy of one or both radar sensors used for diagnosis (z. B. with snow, ice, rainwater, dirt).

In one embodiment it is provided that in the data transmission mode the radar signal to be transmitted is modulated by means of amplitude shift keying (“ASK”). The amplitude of the transmitted radar signal is changed according to a specified modulation scheme in order to encode different values. For example, what is known as “on-off keying” (OOK) can be used as a modulation type, in which the radar signal is switched on and off in order to encode binary values (“0” and “1”) to be transmitted. Deviating from this, however, more than two different amplitude values can also be used for coding, so that more than one bit is transmitted per symbol step.

It is provided that in the data transmission mode (and/or diagnosis mode) the first radar sensor transmits at a predetermined time-varying radar signal transmission frequency and the second radar sensor receives at a fixed predetermined radar signal reception frequency, so that at least at one point in time during this Variation corresponds to the radar signal transmission frequency of the first radar sensor of the radar signal reception frequency of the second radar sensor.

It is e.g. B. very advantageously not necessary to use radar sensors with precisely matched transmission and reception frequencies. Rather, in this embodiment, a sufficiently large variation in the radar signal transmission frequency in the first radar sensor can always ensure that the predetermined reception frequency of the second radar sensor is "hit" at least at one point in time.

Another advantage is z. B. that with regard to the specific selection of the temporal variation of the transmission frequency in the context of the evaluation of the radar signal received from the second radar sensor, an (additional) plausibility check of the evaluation result is advantageously made possible.

If the temporal variation of the transmission frequency z. B. provides that the transmission frequency is varied monotonically starting from an extreme (minimum or maximum) up to a further extreme (e.g. maximum or minimum), a plausibility check of the evaluation result can provide to check whether during this temporal Variation of the radar signal transmission of a data transmission and / or diagnostic radar signal at a certain point in time (when the transmission frequency of the first radar sensor "meets" the reception frequency of the second radar sensor), works.

If, during the variation over time, the transmission frequency is allowed to vary multiple times (e.g. periodically) between certain extreme values, e.g. B. sawtooth between a minimum transmission frequency and a maximum transmission frequency, the plausibility z. B. provide a check as to whether the radar signal transmission works repeatedly during the time variation and / or whether z. B. time intervals between the corresponding times of receipt of the data transmission and / or diagnostic radar signal of the expectation (z. B. period of the variation over time) correspond.

Alternatively, it is provided that in the data transmission mode (and/or diagnostic mode) the first radar sensor transmits at a fixed, predetermined radar signal transmission frequency and the second radar sensor receives at a predetermined time-varying radar signal reception frequency, so that at least at one point in time during this Variation corresponds to the radar signal reception frequency of the second radar sensor of the radar signal transmission frequency of the first radar sensor.

In comparison to the embodiment described above, the roles of the transmission frequency (of the first radar sensor) and the reception frequency (of the second radar sensor) are to a certain extent reversed in this embodiment. While the transmission frequency varies over time in the embodiment described above, the reception frequency varies in this embodiment.

The advantages and possibilities of developments already described for the previously described embodiment thus result in an analogous manner. Provision can thus be made, for example, for the reception frequency to be allowed to vary several times (eg periodically) between predetermined extreme values (eg sawtooth-shaped) during the time variation. A plausibility check can e.g. B. provide a check as to whether the radar signal transmission during the temporal variation at certain times works accordingly and / or whether z. B. correspond to the time intervals between different times of reception of the radar signal of the expectation (z. B. period of the variation over time).

In addition, this embodiment, in which the radar signal transmission frequency is not varied at the first radar sensor and instead the radar signal reception frequency is varied at the second radar sensor, has the additional advantage that existing legal restrictions in many countries regarding permissible radio transmission frequencies or permissible Radio frequency bands can be more easily complied with.

In the invention, the radar sensors can transmit in particular and preferably with a radar signal transmission frequency (possibly carrier frequency or center frequency in the case of a frequency-modulated transmission signal) that is greater than 1 GHz, in particular greater than 10 GHz. On the other hand, the transmission frequency z. B. less than 100 GHz, in particular less than 90 GHz. In one embodiment, the frequency is 24 GHz. Deviating from this, in the invention but in particular z. B. also the ADAS frequency bands 76 GHz - 77 GHz and 77 GHz - 81 GHz be provided.

It goes without saying that a radar sensor, e.g. B. a so-called CW ("continuous wave") radar sensor, in this detection mode at least on the same frequency and possibly or expediently even on a specific frequency band around this frequency (z. B. 24 GHz +/- 10 kHz) too should be able to receive and evaluate.

In the case of a radar that transmits operationally varying on a specific frequency band (e.g. 24 GHz +/- 10 kHz) in acquisition mode sensors, e.g. B. a so-called FMCW ("frequency modulated continuous wave") radar sensor, this should expediently also be able to receive and evaluate at least on the same frequency band or a slightly larger frequency band (e.g. 24 GHz +/- 20 kHz).

The term "radar signal reception frequency" refers to a part of a receiving radar sensor, ie z. B. in the data transmission mode on the part of the second radar sensor, provided for the reception and the evaluation based thereon frequency.

In this regard, it should be noted in particular with regard to the detection operating mode of the radar system (for object detection) that, depending on the specific radar principle used, a receiving radar sensor also requires several reception frequencies or usually even (e.g. in the case of CW, in particular FMCW radar sensors) an entire frequency band for reception is provided and an evaluation of the entire frequency band is carried out. In this case, z. B. a center frequency of the reception frequency band in question can be referred to.

In the context of the data transmission mode (as well as the diagnostic operating mode that may be provided), the term "radar signal reception frequency of the second radar sensor" refers to the frequency for which the second radar sensor carries out reception and evaluation for the purpose of data transmission (or, if applicable, diagnosis of the transmission path ) is carried out.

In one specific embodiment, it is provided that in the data transmission mode the second radar sensor's transmission of a radar signal, which is intended for the detection operating mode, is deactivated. This reliably prevents data transmission from being disrupted by a radar signal transmitted by the second radar sensor. However, it should not be ruled out within the scope of the invention that during the data transmission mode the second radar sensor is also operated to transmit a radar signal in order to (additionally) operate this radar sensor for object detection.

In one specific embodiment it is provided that in the data transmission mode the reception by the second radar sensor takes place with a reception sensitivity which is set to be increased compared to the detection operating mode. This can be advantageous z. B. the fact that in the data transmission mode to be transmitted from the first radar sensor via the transmission path to the second radar sensor radar signal, z. B. due to a specific radiation characteristic of a transmitting device (antenna) of the first radar sensor in question, is emitted with a lower signal intensity (e.g. corresponding to a "side lobe" intensity of the antenna characteristic) than a radar signal emitted in the detection operating mode (e.g. corresponding to a "Main lobe" intensity of the antenna pattern).

Alternatively or additionally, the increased reception sensitivity set in the data transmission mode can also be advantageous if, due to the specific realization of the transmission path (e.g. with several reflection points and/or weak reflection points in the course), a signal from the first radar sensor via the transmission path to the second radar sensor propagating radar signal is more strongly attenuated than a radar signal propagating from the same radar sensor in the detection operating mode to an object and, after reflection on the object, back to the radar sensor (detection radar signal).

One embodiment provides that in the data transmission mode the evaluation takes into account an intensity of the radar signal received from the second radar sensor in order to quantitatively evaluate (as part of a diagnosis) a transmission quality (e.g. channel attenuation) of the transmission path.

• - Senden eines basierend auf einem Datensignal modulierten Radarsignals durch einen ersten Radarsensor der wenigstens zwei Radarsensoren,
• - Empfangen des vom ersten Radarsensor gesendeten Radarsignals durch einen zweiten Radarsensor der wenigstens zwei Radarsensoren, und
• - Auswerten des vom zweiten Radarsensor empfangenen Radarsignals, um damit das Datensignal zurückzugewinnen (Demodulation).

According to a second aspect of the present invention, the object mentioned at the outset is achieved in a radar system of the type mentioned at the outset in that the controller of the radar system is also designed to operate the at least two radar sensors for a transmission of data in a data transmission mode of the radar system, wherein the following steps can be carried out in data transfer mode:

• - Transmission of a radar signal modulated based on a data signal by a first radar sensor of the at least two radar sensors,
• - Receiving the radar signal transmitted by the first radar sensor by a second radar sensor of the at least two radar sensors, and
• - Evaluation of the radar signal received from the second radar sensor in order to recover the data signal (demodulation).

The embodiments and special configurations described here for the operating method according to the invention can, individually or in any combination, also be used in an analogous manner as embodiments or special configurations lines of the radar system according to the invention can be provided (and vice versa).

For example, in the radar system, the control device can be designed to additionally carry out the diagnostic operating mode, e.g. B. at predetermined intervals and / or z. B. simultaneously with the data transmission.

The controller can, for. B. be configured to operate the at least two radar sensors in the data transmission mode so that the first radar sensor transmits with a predetermined radar signal transmission frequency that varies over time and the second radar sensor receives with a fixed predetermined radar signal reception frequency. Alternatively, the controller z. B. be designed to operate the radar sensors in the data transmission mode so that the first radar sensor is transmitted with a fixed predetermined radar signal transmission frequency and the second radar sensor is received with a predetermined time-varying radar signal reception frequency.

The control device can be designed to operate the second radar sensor in the data transmission mode in such a way that its transmission of a radar signal (which is otherwise provided for the detection operating mode) is deactivated and/or its reception sensitivity is set to be increased.

The controller can, for. B. be implemented as a program-controlled electronic control device (z. B. microcontroller, etc.) and control the operation of the individual radar sensors of the radar system by means of appropriate control signals.

In one embodiment, the control device is also designed to carry out an evaluation of the radar signals received from the relevant (operated) radar sensor(s) for the purpose of object detection in the detection operating mode and to carry out an evaluation of the radar signal received from the (at least one) second radar sensor for the purpose of demodulating the same in the data transmission mode ( and thus to recover the data signal or data contained therein).

The control of the individual radar sensors, whether in acquisition mode or in data transmission mode, can in particular include activating and deactivating a transmission mode for transmitting a radar signal and, if necessary, setting a transmission intensity (also e.g. for the aforementioned amplitude shift keying) and/or a transmission frequency, including the aforementioned variation in the transmission frequency of the first radar sensor in data transmission mode.

The control of the radar sensors can also include, in particular, activating and deactivating a reception mode for receiving a radar signal and, if necessary, setting a reception frequency and/or a reception sensitivity, including e.g. B. the aforementioned variation in time of the reception frequency of the (at least one) second radar sensor in data transmission mode and z. B. the already mentioned increase in the reception sensitivity of the (at least one) second radar sensor in the data transmission mode.

In one embodiment of the invention, the radar sensors are each designed to detect the object using the Doppler effect in order to detect the movement of an object (“Doppler radar”). The radar sensors can thus advantageously function as motion sensors, but this does not preclude the radar sensors from being (additionally) designed and/or operated to be suitable for detecting stationary objects.

The Doppler effect is preferably used in that, when transmitting a radar signal with a certain radar signal transmission frequency, also referred to below as "TX signal", a z. B. to coherent signal is held locally (in the relevant radar sensor), hereinafter referred to as local signal or "LO signal", which z. B. is identical to the TX signal or z. B. represents a frequency-shifted version of the TX signal to a predetermined extent, and this LO signal is mixed with the received radar signal, hereinafter also referred to as "RX signal". As a result of the signal mixing of the LO and RX signals, a so-called intermediate frequency signal is created, also referred to below as the "IF signal", whose time profile and spectral composition are each characteristic of a movement speed spectrum of the objects detected by the radar sensor. For an evaluation of the RX signal can therefore in particular z. B. the time profile of the IF signal and / or the spectrum of the IF signal (and / or the time profile of this spectrum) can be evaluated. One possible implementation is for the LO signal to be coherent with the TX signal. However, coherence between the LO and TX or RX signals is not necessary, particularly for the data transmission mode.

If the LO signal is provided identical to the TX signal, this leads to speed of an object (relative to the radar sensor) proportional Doppler shift to a "peak" in the radar signal reception spectrum (RX signal), namely at a peak frequency whose deviation from the frequency of the transmitted radar signal (TX signal or LO signal) is proportional to the speed of the object.

When an object moves away from the radar sensor, the frequency is Doppler shifted down, whereas when the object approaches the radar sensor, the frequency is shifted up. By a suitable evaluation of the IF signal, in particular by determining a frequency-dependent intensity of the IF signal, one or more movement speeds can be detected in a manner known per se.

In principle, if the LO signal is provided as a frequency-shifted version of the TX signal, the same applies. With this measure, only the frequency range of the IF signal provided for object detection, which is also referred to as baseband, is correspondingly frequency-shifted.

In one embodiment, the radar sensors are each designed to operate as a CW radar sensor, in particular an FMCW radar sensor.

Use of the Doppler effect can be provided for a CW radar sensor, for example as described above, and use of the Doppler effect can also be provided for an FMCW radar sensor.

The FMCW radar sensor is a possible or more specific version of a CW radar sensor. With the FMCW radar sensor, a continuously transmitted TX signal is not transmitted with a fixed, predetermined radar signal transmission frequency, but a frequency-modulated TX signal is transmitted. For example, a sawtooth or a sinusoidal or some other periodic frequency modulation can be provided for this purpose. The benefit of frequency modulation of the TX signal is that the TX signal is given a time stamp at any point in time, so that the transit time of the radar signal (from the radar sensor to the object and back) can be determined by evaluating the received radar signal (RX signal) accordingly back) and from this the distance between the radar sensor and the object can be determined. Both the distance and the speed of objects can thus advantageously be detected with an FMCW radar sensor.

As described, one advantage of an FMCW radar is the possibility of directly determining the distance. The speed of an object can alternatively z. B. be determined by at least two successive measurements, or alternatively z. B. via a triangular frequency modulation of the TX signal.

According to a further aspect of the invention, use of the operating method described here and/or the radar system described here on board a vehicle is proposed. A vehicle equipped with such a radar system is also proposed.

One embodiment provides for use in a parking aid (PDC) of a vehicle. One embodiment envisages using it for a distance cruise control of a vehicle. One embodiment provides for the use of an automatic door opening system of a vehicle (e.g. with radar sensors on driver or passenger doors and/or cargo area doors) in order to monitor and monitor the area around the door in question when it is automatically opened (or closed) for safety reasons /or recognize gestures by a user to initiate such opening or closing. One embodiment envisages using it for monitoring the interior (e.g. alarm system) of a vehicle. One embodiment envisages use for a vehicle-mounted radar system for gesture recognition (e.g. foot gesture or hand gesture recognition), e.g. B. with radar sensors for foot gesture recognition in order to initiate automatic door opening (e.g. tailgate opening) and/or automatic door closing.

According to a further aspect of the invention, it is proposed to use the method described here and/or the radar system described here in an inductive charging station for inductively charging electrical energy stores in vehicles. Furthermore, an inductive charging station for inductively charging electrical energy stores in vehicles is proposed, which is equipped with a radar system of the type described here.

When used for an inductive charging arrangement, in particular z. B. a living object detection ("LOD") are in the foreground, so that z. B. the radar system for (pure) object movement detection can be designed.

In particular, with this use (inductive charging) it can be provided that a radar system with radar sensors (e.g. Doppler radar) integrated in the vehicle underbody is used and/or a radar system with radar sensors (e.g. B. Doppler radar) is used.

According to a further aspect of the invention, an inductive charging arrangement is proposed, having an inductive charging station for inductively charging electrical energy storage devices in vehicles, and a vehicle with an electrical energy storage device, the inductive charging arrangement being equipped with a radar system of the type described here, in order in data transmission mode, in particular e.g . B. also during a charging process to be able to transmit data between the inductive charging station and the vehicle (z. B. bidirectional).

According to one embodiment of the use of the method or the radar system in an inductive charging station or an inductive charging arrangement, a nominal (e.g. operationally maximum adjustable) transmission power of at least 3 kW, in particular e.g. B. provided at least 10 kW.

Advantageously, the data transmission implemented according to the invention (at carrier frequencies of, for example, greater than 1 GHz, in particular greater than 10 GHz, and/or, for example, less than 100 GHz, in particular less than 90 GHz) is less sensitive to interference from the charging process (or discharging) generated alternating magnetic field than most of the data transmissions known from the prior art with radio signals between the vehicle and inductive charging station. With the invention, a robust communication interface can thus be created between the inductive charging station and the vehicle, which functions trouble-free before, after and in particular during the charging process. In one embodiment, the data transmission implemented according to the invention is provided as an additional (and particularly robustly functioning) communication path to a conventionally designed communication path.

• 1 ein Radarsystem mit mehreren Radarsensoren gemäß eines Ausführungsbeispiels,
• 2 einen der im Radarsystem von 1 verwendeten Radarsensoren gemäß eines Ausführungsbeispiels,
• 3 eine jeweils für die Radarsensoren in dem Radarsystem von 1 eingesetzte Signalverarbeitungseinrichtung gemäß eines Ausführungsbeispiels,
• 4 Zeitverlaufsdiagramme zur Veranschaulichung eines Erfassungsbetriebsmodus bei dem Radarsystem von 1,
• 5 Zeitverlaufsdiagramme zur Veranschaulichung der Bewerkstelligung eines Datenübertragungsmodus bei dem Radarsystem von 1,
• 6 Zeitverlaufsdiagramme zur Veranschaulichung einer Datenübertragung,
• 7 ein Flussdiagramm eines Verfahrens zum Betreiben eines Radarsystems,
• 8 ein mit einem Radarsystem ausgestattetes Fahrzeug,
• 9 eine mit einem Radarsystem ausgestattete Induktivladestation, und
• 10 eine mit einem Radarsystem ausgestattete Induktivladeanordnung.

The invention is described in more detail below using exemplary embodiments with reference to the accompanying drawings. They represent:

• 1 a radar system with multiple radar sensors according to an embodiment,
• 2 one of the in the radar system of 1 used radar sensors according to an embodiment,
• 3 one for each of the radar sensors in the radar system of FIG 1 used signal processing device according to an embodiment,
• 4 Timing diagrams illustrating a detection mode of operation in the radar system of FIG 1 ,
• 5 Timing diagrams illustrating the implementation of a data transmission mode in the radar system of FIG 1 ,
• 6 Timing diagrams to illustrate data transmission,
• 7 a flowchart of a method for operating a radar system,
• 8th a vehicle equipped with a radar system,
• 9 an inductive charging station equipped with a radar system, and
• 10 an inductive charging arrangement equipped with a radar system.

1 shows a radar system 10, having two radar sensors 20-1 and 20-2 for a respective object detection by sending a radar signal TX-1 or TX-2, receiving a radar signal RX-1 or RX- reflected on an object (not shown). 2 and evaluating the received radar signal RX-1 or RX-2.

The reference numbers of the embodiment provided twice, but analogous in their effect components such. B. the radar sensors 20-1 and 20-2 are numbered (each supplemented by a hyphen and the number "1" or "2"). In the following, reference is also made to individual such components or to the totality of such components by the non-supplemented reference number.

The radar system 10 also has a control device 50 which is designed to operate the two radar sensors 20 in a detection operating mode of the radar system 10 in each case for object detection. The several (in the example two) radar sensors 20-1 and 20-2 can be used in the detection mode of operation, e.g. B. be operated simultaneously, or z. B. only as needed and thus in particular z. B. also individually.

Each of the radar sensors 20 has a specific detection range in which objects reflecting radar radiation can be detected. In a manner known per se, distance detection and/or motion detection can be provided for each of radar sensors 20 in the detection operating mode.

For detecting the distance, the transit time from the radar sensor 20 to the object and back to the same radar sensor 20 can be determined by evaluating the signal RX, and the distance of the object from the relevant radar sensor 20 can thus be determined.

For motion detection, the frequency shift (Doppler shift) of the radar signal RX with respect to the transmitted radar signal TX and from this the speed of movement of the object can be determined by evaluating the radar signal RX.

The two radar sensors 20-1 and 20-2 have an identical structure, which is described below with reference to FIG 2 is explained.

2 shows a radar sensor 20 (one of the radar sensors 20-1, 20-2 in 1 ), having a voltage-controlled oscillator (VCO) 22 for generating a high-frequency signal whose frequency can be varied by means of a control signal c1, which high-frequency signal is split by means of a branching device 24 into two coherent signals TX and LO. The signal TX serves as a transmission signal of the radar sensor 20 and can be fed to a transmission antenna 28 via a switching device 26, which can be controlled by means of a control signal c2, in order to transmit the radar signal TX. The signal LO serves as the local signal of the radar sensor 20 and is fed to a first input of a mixer 30 . The radar signal RX received by means of a receiving antenna 32 is supplied as a received signal RX to a second input of the mixer 30 via an amplifier 34 that can be controlled by means of a control signal c3. An intermediate frequency signal IF is output as the resultant signal at an output of the mixer 30 .

Deviating from the in 2 In the example shown of a VCO for frequency generation in the radar sensors, a different design of an HF signal generator can also be provided within the scope of the invention.

3 12 shows a signal processing device 40 to which the intermediate frequency signal IF is supplied at an input and which outputs a digital representation of the signal IF in the form of a digital data signal d at an output. In the exemplary embodiment shown, the signal processing device 40 includes a bandpass filter 42 and an analog/digital converter 44 in order to subject the intermediate frequency signal IF to bandpass filtering and to output the filtered signal in analog/digital converted form as the data signal d.

coming back on 1 For each of the radar sensors 20-1, 20-2, the respective data signal d is supplied to a control device 50 that is used jointly for both radar sensors 20-1, 20-2.

The control device 50 is implemented as a program-controlled electronic control device in order to operate the two radar sensors 20 (by generating the corresponding control signals c1, c2 and c3) and also to carry out the evaluation of the respective data signals d during operation of the radar system 10. In one embodiment, the control device 50 is structurally combined with the other 1 apparent components of the radar system 10 formed. Alternatively, however, the controller 50 z. B. can be connected to these components via a digital communication bus system.

4 FIG. 2 ) is operated for object detection.

4 The above shows a time profile of the control signal c1 (voltage signal) for driving the oscillator 22. In the example shown, a sawtooth-shaped control signal c1 is provided which varies over time t.

4 middle shows a time profile of a frequency fTX of the transmission signal TX and thus of the radar signal transmitted by the radar sensor 20 . The frequency fTX also varies in a sawtooth manner around a center frequency fTXo provided for the oscillator 22 in accordance with the signal c1.

4 below shows a time course of a frequency fRX of the received radar signal and thus of the received signal RX. This curve over time is also sawtooth-shaped in accordance with the curve over time of the frequency fTX of the transmission signal TX (and accordingly of the local signal LO) and varies around a center reception frequency fRXo. However, as can be seen from the figure, the time profile of the frequency fRX is delayed by a period of time Δt compared to the time profile of the frequency fTX, and the center frequency fRXo is also increased by a frequency difference Δf compared to the center frequency fTXo.

During operation of the radar system 20, these detection parameters Δt and Δf can be determined, for example, using the data signal d. Alternatively, the detection parameters could e.g. B. be determined independently in the respective radar sensor 20. The period of time Δt corresponds to the propagation time of the radar signal from radar sensor 20 to the object and back, from which control device 50 can thus determine the distance of the object, and the frequency difference Δf corresponds to the Doppler shift of the radar signal, from which control device 50 can thus determine the speed of the object can. In particular, if the control device 50 is not structurally combined with the other components of the radar system 10, but z. B. via a digital communication bus system tem (e.g. CAN bus, LIN bus, etc.), the signal processing devices 40 assigned to the individual radar sensors 20 can differ from the representation in 3 also additionally be designed to initially further process the data resulting from the analog-to-digital conversion in order to at least partially carry out the evaluation required for object detection and thus z. B. to relieve the control device 50 and / or said communication bus system accordingly.

For static objects (no Doppler frequency shift), the following applies: fLO = fRX + Δf _travel , where fLO denotes the frequency of the local signal LO and Δf _travel denotes a frequency difference, which is due to the runtime-related time offset (between transmission and reception times) in connection with the frequency modulation of the signals LO and TX results. The LO signal has “continued” in the receiver (ie its frequency has increased), while the TX signal has the frequency at the (slightly earlier) point in time. However, since both frequency ramps (for LO and TX) have the same slope, the IF signal is one with a constant frequency. For moving objects, a Doppler frequency shift Δf _Doppler is superimposed on the frequency shift Δf _travel of the transit time shift. In this case, it is therefore not possible to differentiate between object distance/object speed simply by determining the instantaneous frequency of the IF signal.

the 4 FIG. 12 shows an example of object detection that is idealized insofar as the transmitted radar signal is reflected on a single object at a well-defined distance and well-defined speed and is received again by radar sensor 20. In real use of the radar system 10, more complicated scenarios can also occur when detecting objects by means of each radar sensor 20. Up to a certain degree of complexity, however, the distances and speeds of the individual objects can then also be determined by appropriate signal evaluation.

Although 4 shows an example of a detection mode of operation in which the radar sensors 20 are operated as FMCW radar sensors. B. the control signal c1 is kept constant (or e.g. is regulated in such a way that the frequency generated by the oscillator 22 (and thus the frequency of the transmission signal TX) is kept constant. In this case, only moving objects would be detected by the radar sensor 20 (pure " Doppler radar"). Such a CW radar sensor is only sensitive to the speeds of the reflection objects and hides stationary objects. In the automotive sector, Doppler radars are ideal for motion detection in strong reflection environments such as metal garages or narrow parking lot situations, and thus in particular also for use in an inductive charging arrangement for vehicles, ie with radar sensors on the vehicle (e.g. underbody) and/or with radar sensors on a charging station (e.g. on a floor panel).

In a 24 GHz radar system with radar sensors designed to use the Doppler effect on board a vehicle, the intermediate frequency range that can be evaluated (bandwidth of the signal IF) can change, e.g. B. extend over less than 5 kHz, in particular less than 1 kHz, since this is sufficient in terms of the speeds of normal traffic objects.

• - Senden eines basierend auf einem Datensignal modulierten Radarsignals TXD durch (wenigstens) einen ersten Radarsensor, hier z. B. den Radarsensor 20-1, der beiden (allgemein: mehreren) Radarsensoren 20-1, 20-2,
• - Empfangen des vom ersten Radarsensor 20-1 gesendeten Radarsignals TXD durch einen (davon verschiedenen, wenigstens einen) zweiten Radarsensor, hier den Radarsensor 20-2, der beiden Radarsensoren 20-1, 20-2, und
• - Auswerten des vom zweiten Radarsensor 20-2 (als dessen Empfangssignal) empfangenen Radarsignals, um damit das Datensignal empfängerseitig zurückzugewinnen.

A special feature of the radar system 10 is that the control device 50 is designed to operate the two radar sensors 20-1, 20-2 for data transmission in a "transmission mode" of the radar system 10, the following steps being carried out in the data transmission mode:

• - Sending a modulated based on a data signal radar signal TXD by (at least) a first radar sensor, here z. B. the radar sensor 20-1, the two (generally: several) radar sensors 20-1, 20-2,
• - Receiving the radar signal TXD sent by the first radar sensor 20-1 by a (different, at least one) second radar sensor, here the radar sensor 20-2, of the two radar sensors 20-1, 20-2, and
• - Evaluation of the radar signal received from the second radar sensor 20-2 (as its received signal) in order to thereby recover the data signal at the receiver end.

In the example, the data transmission mode can be triggered centrally for all radar sensors 20 involved using the control device 50 (eg via a digital communication bus system such as eg CAN bus or eg LIN bus).

In the exemplary embodiment shown, the transmission path is advantageously realized by a "direct line of sight" (for radar signals) between the two radar sensors 20-1, 20-2, i. H. the radar signal TXD can propagate directly (without reflection) from the radar sensor 20-1 to the radar sensor 20-2.

The data transmission mode is carried out as required when the radar system 10 is in operation.

In the example shown, in data transmission mode, first radar sensor 20-1 transmits at a fixed, predetermined radar signal transmission frequency, and second radar sensor 20-2 receives at a predetermined radar signal reception frequency that varies over time, so that at least at one point in time during this variation, the radar signal - Receiving frequency of the second radar sensor 20-2 corresponds to the radar signal transmission frequency of the first radar sensor 20-1.

5 illustrates this special feature provided in the example for implementing the data transmission mode, in which the first radar sensor 20-1 transmits the radar signal TXD at a fixed, predefined radar signal transmission frequency fTXD, in that the control device 50 supplies the radar sensor 20-1 with a constant control signal c1 (or A control signal c1 regulated in such a way that the constant frequency fTXD is brought about with it).

5 shows in four partial representations on a common time axis (time t) temporal profiles of certain signals or parameters in the second (receiving) radar sensor 20-2.

5 at the top shows a time profile of the control signal c1 fed to the second radar sensor 20-2 by the control device 50 during the data transmission mode. In the example shown, a sawtooth variation of the control signal c1 is provided.

The subsequent partial representation of 5 shows a time course of a frequency of the signal generated by the oscillator 22 caused thereby and thus a frequency fLO of a local signal LO branched off therefrom. According to the variation of the control signal c1, the frequency fLO also varies in a sawtooth pattern around a center frequency fLOo. As an alternative to a sawtooth shape, a different variation, e.g. B. sinusoidal or z. B. triangular, be provided for the receiver-side control signal c1 and thus the frequency fLO.

In 5 only one period of this temporal variation is shown, repeated many times during performance of the data transfer mode (as referred to below with reference to FIG 6 explained later).

How out 5 As can be seen, the illustrated temporal variation of the frequency fLO causes the frequency fLO in the radar sensor 20-2 to correspond to the radar signal transmission frequency fTXD of the radar sensor 20-1 at one point in time during each period of this variation.

A suitable evaluation of the radar signal TXD received from the radar sensor 20-2 can therefore advantageously z. B. can be diagnosed whether the radar signal transmission of the radar signal TXD works on the transmission path or whether this transmission path is impaired. Knowing that the two radar sensors 20-1, 20-2 are stationary relative to one another and their relative speed to one another is therefore zero, this z. B. carried out by the control device 50 evaluation takes into account that no Doppler shift occurs during the transmission of the radar signal TXD. If the transmission path is functional, it is therefore to be expected that at a particular point in time within each period in the frequency spectrum of the intermediate frequency signal IF generated in radar sensor 20-2 at the relevant, i. H. for a relative speed of zero relevant frequency, a greatly increased intensity ("peak") will occur.

The penultimate partial representation in 5 shows a corresponding peak in a time profile of a signal intensity Int(IF) which is representative of the intensity of said frequency component. In the example shown, this peak occurs at a point in time t _D within the period shown.

The control device can thus diagnose the function of the transmission path by checking the signal IF (or the digital representation d thereof) to determine whether such a peak is as expected, i. H. in the example shown, it may or may not occur once per period of variation. If this occurs, the control device 50 then assesses, with the aid of diagnostic software running therein, that the transmission path is functioning. Otherwise, ie if said peak in the frequency spectrum of the signal IF does not occur as expected, the control device 50 evaluates this as an impairment of the transmission path.

The bottom part of the illustration 5 shows this error case in a corresponding representation, in which the said peak does not occur or only occurs with a greatly reduced intensity. In one embodiment, the peak intensity is detected by the control device 50 in order to carry out a qualitative assessment of the transmission quality of the transmission path. The lower the peak intensity, e.g. B. can be determined based on a peak value and / or an integral of the peak, the lower the transmission quality is rated.

6 illustrated using time course diagrams similar to those of 5 , but over several periods of the receiver side gene variation of the control signal c1 ( 6 middle), the actual data transmission.

6 The above shows an example of a data signal c4 provided for transmission at the transmitter end, ie at the first radar sensor 20-1, which in this example represents a sequence “...0110101...” of binary values (bits). In the example shown, the data signal c4 changes between a high level and a low level, with in 6 the times of the corresponding transitions are marked with t1 and t2.

In the example, the data signal c4 is used directly to switch the radar signal TXD sent by the first radar sensor 20-1 on and off in order to transmit the data signal c4 to the second radar sensor 20-2 by means of “on-off keying” modulation of the radar signal TXD . The data signal c4 is used in the first radar sensor 20-1 as the control signal c2 (cf. 2 ) is used to control the switching device 26 in order to feed the signal TX from the oscillator 22 to the transmitting antenna 28 depending on the binary value ("0" or "1") of the data signal c4 (e.g. with a binary value "1") or not (e.g. B. with binary value "0").

6 below shows the signal Int(IF) resulting in this example as part of the receiver-side evaluation of the radar signal RX with the already referred to in FIG 5 "Peaks" explained, whereby these peaks correspond to the periodicity of the signal c1 ( 6 middle) occur periodically, but do not occur in the temporal phases with the radar signal TXD switched off according to the modulation.

Therefore, the evaluation of the radar signal RX carried out by the receiver in a time grid corresponding to the periodicity can interpret the occurrence and absence of the peaks as binary values "1" or "0" and thus the data signal c4 (in the example: "...0110101..." ) recover, as in 6 shown below.

7 shows steps of an operating method for a radar system with multiple radar sensors, as z. B. with the radar system 10 of 1 can be carried out.

In a step S0, one or more of the plurality of radar sensors 20 are operated for object detection (in particular, for example, as CW radar sensors).

In a z. B. periodically repeated step S1, it is checked whether there is a need for data transmission (z. B. due to a corresponding request). After a need for data transmission determined by the control device 50 in step S1, the radar system 10, e.g. B. immediately, or z. B. at a next "favourable time" z. B. after completion of an ongoing object detection process, into the data transmission mode, in which in a step S2 one of the radar sensors 20 is operated to transmit the data transmission radar signal TXD and another of the radar sensors 20 is operated in a step S3 to receive the radar signal TXD. In a step S4 included in the data transmission mode, the radar signal TXD received from the second radar sensor is evaluated (including demodulation) in order to implement the data transmission (eg with or eg without diagnosis of the transmission path).

After the data transmission mode has been carried out, the radar system 10 switches back to the detection operating mode according to step S0.

If different from the example of 1 a radar system with more than two radar sensors is provided for a respective object detection, according to one embodiment it is provided that in the data transmission mode a data transmission (carried out simultaneously or successively, or possibly carried out in several different data transmission modes) is carried out over several different transmission paths if necessary. With a number n of radar sensors, there are n! / (2 x (n-2)!) combinatorial options for selecting a "first" and a "second" radar sensor from the total of n radar sensors (without considering the order), through which a transmission path is defined in each case, which (under the premise an existing transmission path) can be used for data transmission according to the invention.

8th shows a vehicle 1 which is equipped with a radar system 10 of the type described here. In 8th only the radar sensors 20-1 to 20-4 (four in this example) are shown for the sake of simplicity.

The radar sensors 20-1 to 20-4 are arranged on the outside of a left front door, a left rear door, a right front door, and a right rear door, respectively, and function as sensors for ensuring safety in an automatic opening of the respective ones in a detection operation mode of the radar system vehicle door.

The radar system is in this example in the vehicle 1 in particular z. B. used to ensure that there is no obstacle in front of the respective door when each of the four doors is opened automatically. Alternatively or additionally, based on the result of the object detection solution, each time one of the doors is opened, an individual limitation of the opening path of the door in question must be provided.

In the example shown, when one of the doors is intended to be actuated (opening or closing), only the radar sensor assigned to this door is operated for object detection, i. H. when the left front door is actuated, only radar sensor 20-1, when the left rear door is actuated, only radar sensor 20-2, etc.

When the radar system is in operation, it changes as required (i.e. when there is data to be transmitted), e.g. B. in predetermined "opportune times or intervals", in a data transmission mode to z. B. to be able to transmit data via a first transmission path running from radar sensor 20-1 to radar sensor 20-2 and via a second transmission path running from radar sensor 20-3 to radar sensor 20-4.

In the example shown, the spatial angle-dependent antenna characteristics of all transmitting and receiving antennas of radar sensors 20-1 to 20-4 each have a maximum of the radiation or a maximum of the reception sensitivity in a direction orthogonal to a respective plane of the door, in order to use the left radar sensors 20-20 1 and 20-2 to detect objects to the left of the associated doors and by means of the right radar sensors 20-3 and 20-4 objects to the right of the associated doors. In addition, the antenna characteristic of the radar sensors 20-1 to 20-4 shows a significant (i.e. sufficient for the data transmission mode) emission intensity or reception sensitivity in a direction parallel to the plane of the doors (longitudinal direction of the vehicle), so that there are advantageously direct line-of-sight connections for data transmission radar signals. which are transmitted in data transmission mode from radar sensor 20-1 to radar sensor 20-2 and/or vice versa, and from radar sensor 20-3 to radar sensor 20-4 and/or vice versa.

In general, in the case of use for object detection in the vicinity of a vehicle, as in the example of 8th in front of side doors of a vehicle, advantageous for. B. an exposed (from a vehicle outer skin protruding) installation position of the radar sensors can be provided, z. B. on or in door handles. Alternative attachment or installation positions on the vehicle are e.g. B. in a sill area, on an A, B or C pillar, on a roof line, or on a side mirror.

The radar sensors 20-1 to 20-4 can e.g. B. have corresponding main lobes and side lobes in their antenna characteristics, or z. B. more or less evenly covering a semicircle or a hemisphere antenna characteristics.

9 shows an inductive charging station 2 equipped with a radar system 10 of the type described here.

The inductive charging station 2 is provided for inductively charging electrical energy stores in vehicles (e.g. electric vehicles, hybrid vehicles, etc.) and includes an in 9 visible, in use situation arranged on a floor or embedded in the floor, which has a square contour in the example shown, with several (here: four) radar sensors 20-1 to 20-4 distributed over the surface of the floor plate distributed over the circumference of the floor plate are arranged protruding.

In the example shown, the antenna characteristics of all transmitting and receiving antennas of radar sensors 20-1 to 20-4 show a radiation intensity or reception sensitivity in all lateral directions (360° antenna characteristics), so that all radar sensors 20-1 to 20 -4 simultaneously for object detection in respective, in 9 dashed detection areas to operate.

A control device of radar system 10 is designed to operate radar sensors 20-1 to 20-4 in data transmission mode for data transmission within this radar system.

Deviating from the use of the in 9 illustrated and equipped with the radar sensors 20-1 to 20-4 as a component of the "stationary" part of an inductive charging arrangement for vehicles is also possible, a similarly designed (i.e. equipped with several radar sensors) base plate or the like as a component of the "mobile “Provide part of an inductive charging arrangement, ie to be installed in a vehicle underbody of a vehicle. In this case, the vehicle itself (as an alternative to or in addition to the inductive charging station) is equipped with a radar system, which advantageously also enables object detection, in particular for the purpose of so-called "living object detection", and in which data is also advantageously transmitted within the vehicle's radar system can.

Is advantageous in the context of the invention in the application of an inductive charging z. B. a combined use of radar sensors on the one hand on the vehicle and on the other hand at the inductive charging station, wherein the radar system according to the invention comprises (at least) one radar sensor on the vehicle and (at least) one radar sensor on the inductive charging station. In this case, particularly advantageously, data can also be transmitted between the vehicle (or a vehicle currently located at the charging station) and the charging station. An example of such an inductive charging arrangement is described below with reference to FIG 10 described.

10 shows an inductive charging arrangement 3 equipped with a radar system 10 of the type described here, which is formed by an inductive charging station 2 (“stationary part”) and a vehicle 1 (“mobile part”) (which is located at the inductive charging station while it is being charged or discharged).

For inductive charging of the vehicle 1, the inductive charging station 2 includes a charging unit 4 containing a coil 5 (primary coil during charging). To load vehicle 1, it is first loaded as in 10 shown parked in the area of the inductive charging station 2 in such a way that a coil 8 located in a charging unit 7 of the vehicle 1 (secondary coil during charging) reaches a suitable positioning with respect to the coil 5 . In the example, the coil is 8 z. B. approximately coaxially above the coil 5. In this arrangement situation, electrical power can then be transmitted in a known manner from the coil 5 via a transmission area 9 to the coil 8 by means of a corresponding control by a station-side (and supplied with electrical energy) charging control unit 14.

In 1 Dashed lines are field lines of the alternating magnetic field generated by the coil 5, which induces an alternating voltage in the coil 8, which is rectified via a vehicle charging control unit 11 to an on-board electrical system 12 containing, among other things, an electrical energy store. Starting from the vehicle electrical system 12, electrical energy can be used during operation of the vehicle 1, for example to supply a drive device 13 of the vehicle 1. In the example shown, the loading unit 4 has the form of a "base plate" which is embedded in the ground or in a drivable foundation that is sunk into the ground. The ground level is marked with B.

The problem is that foreign bodies can get into the area of the inductive charging station 2, which represents a not inconsiderable risk potential. If, for example, foreign bodies consisting of or containing ferromagnetic material get into the transmission area 9 during an energy transmission process, they can heat up considerably due to eddy current effects, which impairs the efficiency of the inductive energy transmission and z. B. can also lead to a fire hazard. Furthermore, living foreign bodies (e.g. small animals) that are in the magnetic field during the charging process are also endangered as such.

In the example, the radar system 10 comprises four radar sensors 20-1 to 20-4 on the charging unit (floor plate) 4 on the station side and another four radar sensors 20'-1 to 20'-4 on the charging unit 7 on the vehicle side to the charging station 2 and/or vice versa, for which purpose one of the radar sensors 20-1 to 20-4 and one of the radar sensors 20'-1 to 20'-4 can be selected as the "first" and "second" radar sensors to be used in the data transmission mode and accordingly are to be operated.

Claims (11)

Method for operating a radar system (10), wherein the radar system (10) has at least two radar sensors (20-1, 20-2) for a respective object detection by transmitting a radar signal (TX), receiving a radar signal (RX) reflected on an object, and evaluating the received radar signal (RX), and wherein the method provides a detection operating mode in which the at least two radar sensors (20-1, 20-2) are operated for object detection, wherein the method also provides a data transmission mode, having the following steps: - Transmission of a radar signal (TXD) modulated based on a data signal (c4) by a first radar sensor (20-1) of the at least two radar sensors (20-1, 20-2), - Receiving of the first radar sensor (20-1) transmitted Radar signal (TXD) by a second radar sensor (20-2) of the at least two radar sensors (20-1, 20-2), and - evaluating the second radar sensor (20-2) received radar signal (TXD) in order to use the data signal (c4), and wherein in the data transmission mode the first radar sensor (20-1) transmits at a predetermined time-varying radar signal transmission frequency and the second radar sensor (20-2) receives at a fixed predetermined radar signal reception frequency, so that at least at one point in time during this variation, the radar signal transmission frequency of the first radar sensor (20-1) corresponds to the radar signal reception frequency of the second radar sensor (20-2), or wherein in the data transmission mode the first radar sensor (20-1) transmits at a fixed, predetermined radar signal transmission frequency (fTXD) and the second radar sensor (20-2) receives at a predetermined time-varying radar signal reception frequency (fLO), so that at least at one point in time during this variation, the radar signal reception frequency (fLO) of the second radar sensor (20-2) corresponds to the radar signal transmission frequency (fTXD) of the first radar sensor (20-1). procedure after claim 1 , whereby in the data transmission mode the radar signal (TXD) to be transmitted is modulated by means of amplitude shift keying. Method according to one of the preceding claims, in which, in the data transmission mode, the second radar sensor (20-2) has its transmission of a radar signal (TX-2) provided for the detection operating mode deactivated. Method according to one of the preceding claims, in which, in the data transmission mode, the reception by the second radar sensor (20-2) takes place with a reception sensitivity which is set to be increased compared to the detection operating mode. Method according to one of the preceding claims, wherein in the data transmission mode the evaluation takes into account an intensity of the radar signal (TXD) received from the second radar sensor (20-2) in order to determine a transmission quality of a signal from the first radar sensor (20-1) to the second radar sensor (20-2) running transmission path to evaluate quantitatively. Radar system (10), having at least two radar sensors (20-1, 20-2) for a respective object detection by transmitting a radar signal (TX), receiving a radar signal (RX) reflected on an object and evaluating the received radar signal (RX), and a control device (50) which is designed to operate the at least two radar sensors (20-1, 20-2) for object detection when the radar system (10) is in a detection operating mode, wherein the control device (50) is also designed to Data transmission mode of the radar system (10) to operate the at least two radar sensors (20-1, 20-2) for a transmission of data, the following steps being carried out in the data transmission mode: - Transmission of a radar signal (TXD) modulated based on a data signal (c4) by a first radar sensor (20-1) of the at least two radar sensors (20-1, 20-2), - Receiving the radar signal (TXD) sent by the first radar sensor (20-1) by a second radar sensor (20-2) of the at least two radar sensors (20-1, 20-2), and - evaluating the radar signal (TXD) received from the second radar sensor (20-2) in order to thereby recover the data signal (c4), wherein the first radar sensor (20-1) is designed to transmit in data transmission mode with a predetermined time-varying radar signal transmission frequency and the second radar sensor (20-2) is designed to receive with a fixed predetermined radar signal reception frequency, so that at least at a point in time during this variation, the radar signal transmission frequency of the first radar sensor (20-1) corresponds to the radar signal reception frequency of the second radar sensor (20-2), or wherein the first radar sensor (20-1) is designed to transmit in data transmission mode with a fixed, predetermined radar signal transmission frequency (fTXD) and the second radar sensor (20-2) is designed to receive with a predetermined time-varying radar signal reception frequency (fLO). , so that at least one point in time during this variation corresponds to the radar signal reception frequency (fLO) of the second radar sensor (20-2) of the radar signal transmission frequency (fTXD) of the first radar sensor (20-1). Radar system (10) after claim 6 , wherein the radar sensors (20-1, 20-2) are each designed to carry out the object detection using the Doppler effect in order to realize an object movement detection. Radar system (10) after claim 6 or 7 , wherein the radar sensors (20-1, 20-2) are each designed to operate as a CW radar sensor, in particular an FMCW radar sensor. Vehicle (1) equipped with a radar system (10) according to one of Claims 6 until 8th . Inductive charging station (2) for inductively charging electrical energy storage devices of vehicles (1), the inductive charging station (2) having a radar system (10) according to one of Claims 6 until 8th Is provided. Inductive charging arrangement (2, 1), having an inductive charging station (2) for inductively charging electrical energy stores in vehicles, and a vehicle (1) with an electrical energy store, the inductive charging arrangement (2, 1) having a radar system (10) according to one of Claims 6 until 8th is equipped to transmit data between the inductive charging station (2) and the vehicle (1) in the data transmission mode of the radar system (10).

Images