DE102020204381A1 - Method for operating a radar system and radar system - Google Patents

Abstract

The invention relates to a method for operating a radar system (10), the radar system (10) having at least two radar sensors (20-1, 20-2) for a respective object detection by sending a radar signal (TX), receiving a radar signal reflected on an object (RX), 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. In order to increase the benefit in the operation of the radar system (10), the method according to the invention also provides a “data transmission mode”, comprising the following steps: Sending a radar signal (TXD) modulated based on a data signal (c4) by a first radar sensor (20) -1) the at least two radar sensors (20-1, 20-2); Receiving the radar signal (TXD) transmitted 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); Evaluation of the radar signal (TXD) received from the second radar sensor (20-2) in order to recover the data signal (c4). The invention also proposes a radar system (10) designed to carry out such a method and advantageous uses for this, for example in inductive charging stations for electric vehicles.

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 8.

Such a method for operating the radar system provides a detection mode in which several radar sensors of the radar system can be operated for object detection, each object detection being accomplished by sending 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, for example in stationary applications such as B. in trade and household (motion detectors, surveillance technology, etc.), or for example in automotive technology, for example in radar systems with radar sensors for distance determination (parking aid, 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 it enables isolated object detection 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 the case of a vehicle with one or more automatically or motorized doors with a radar system for detecting any obstacles, at least one radar sensor per door can be used, for example, in order to safely initiate or with automatic door opening processes (and / or door closing processes) through the respective object detection to inactivate or stop an obstacle detected by the object detection, the door opening (or door closing), or z. B. to realize an adjustment of the door only until shortly before the obstacle.

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 field 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:

• - Sending 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 sent 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 noteworthy additional expenditure in terms of “hardware”.

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 as well as their respective purpose in the context of data transmission (the "first radar sensor" sends the " second radar sensor "receives).

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

If the radar system z. B. has two or three radar sensors, so within the scope of the invention, for. For example, it can be provided that each of these two or three sensors can be used as the first radar sensor in the data transmission mode. In a preferred embodiment, however, only a single radar sensor is operated as the first radar sensor at any point in time. In principle, however, each of the two or three sensors can also be used as the second radar sensor (if not already used as the first radar sensor at the same time). If the radar system has more than two radar sensors, the invention can therefore in principle implement respective unidirectional or bidirectional data transmission connections for any pairs of these radar sensors.

The use of the data transmission connection implemented according to the invention in a radar system can in practice, for. B. consist in at least one or z. B. 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 a comparatively lower data processing power (and thus more cost-effective). B. can transmit data resulting from object recognition for further processing to the or a more powerful radar sensor.

Another benefit of the data transmission connection implemented according to the invention can be, for. B. consist in accomplishing or improving a synchronization that is advantageous or even necessary for the operation of the radar system between different ones of the radar sensors by transmitting data for such a synchronization.

Furthermore, the data transmission connection can also be useful for radar sensors that are communicatively connected to one another (e.g. in a vehicle) anyway via a digital communication bus system (e.g. CAN bus, LIN bus, etc.) because the communication bus system is thereby can be relieved. In modern vehicles, communication bus systems of this type are often used to capacity close to their performance limits, so that with the invention, for. 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 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 as such by the radar system as such or by the installation environment of the radar system (technical device such as a vehicle). 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 variant, 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 transmission of radar signals 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 the data transmission mode can in practice, for. B. be guaranteed by using so-called side lobes of the antenna characteristics concerned. In a corresponding embodiment, the first and second radar sensors are z. B. arranged with at least approximately parallel main directions or main lobes of the antenna characteristics offset from one another in the lateral direction, the main lobes being primarily used in the detection operating mode. It can then arise that in the data transmission mode z. B. mainly 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 construction of the radar system or its installation environment ensures that the radar signal transmission via this transmission path from the first radar sensor is made possible via one or more radar signal reflections up to the second radar sensor. This also advantageously creates a transmission path independent of the presence of any objects in the detection range of the radar system.

To create such an indirect line of sight, for example, bumpers and / or side mirrors can be used as (parasitic) reflection objects in a vehicle equipped with the radar system. As an alternative or in addition, the vehicle can have add-on parts arranged specifically for this purpose. Each of such reflection objects can be used to enlarge 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 further development of the invention it is provided that the method also provides a diagnostic operating mode, having the following steps:

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

In the case of the radar signal sent according to this development, it can be, for. B. to be the invention anyway provided, based on a data signal modulated radar signal. In this case, the evaluation of the radar signal received by the second radar sensor would serve not only 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 performing the diagnosis during a data transmission mode, such a diagnosis takes place at other times (or independently of the data transmission).

If in the diagnostic operating mode, be it during or separately from a data transmission mode, the evaluation of the radar signal received by 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 occupancy of one or both radar sensors (e.g. with snow, ice, rainwater, dirt, etc.) can advantageously be excluded.

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, an improper operability of the radar system is diagnosed.

The imperfect function can z. Be diagnosed based on a determination of an excessively decreased (e.g., below a predetermined threshold) radar signal intensity. If a diagnostic operating mode is carried out during a data transmission mode, the imperfect function can alternatively or additionally also, for. B. be diagnosed based on an evaluation of a data error rate at the receiving end, in that the transmission path is assessed as impaired in the event of an excessively increased (e.g. above a predetermined threshold) error rate (e.g. bit error rate). An error rate can e.g. B. be determined in the context 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 z. For example, errors can be detected that are caused by an occupancy of one or both of the radar sensors used for diagnosis (e.g. 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 predetermined modulation scheme in order to encode different values. For example, so-called “On-Off Keying” (OOK) can be used as the type of modulation, in which the radar signal is switched on or off in order to encode binary values to be transmitted (“0” and “1”). In contrast to 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.

In one embodiment it is provided that in the data transmission mode (and / or diagnostic mode) the first radar sensor transmits with a predefined time-varying radar signal transmission frequency and the second radar sensor receives with a fixed 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 corresponds to the radar signal reception frequency of the second radar sensor.

So it is z. 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 case of the first radar sensor can always ensure that the predefined reception frequency of the second radar sensor is “hit” at least at one point in time.

Another advantage is e.g. B. in that with regard to the specific choice of the temporal variation of the transmission frequency in the context of the evaluation of the radar signal received by 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 starting from one extreme (minimum or maximum) monotonically to a further extreme (z. B. maximum or minimum), a plausibility check of the Provide evaluation results to check whether the radar signal transmission of a data transmission and / or diagnostic radar signal at a certain point in time (namely when the transmission frequency of the first radar sensor "hits" the reception frequency of the second radar sensor) functions during this time variation.

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

In another, but to a certain extent similar or “reverse” embodiment, it is provided that in the data transmission mode (and / or diagnostic mode), the first radar sensor transmits with a predetermined radar signal transmission frequency and the second radar sensor receives with a predetermined, time-varying radar signal Reception frequency takes place, so that at least one point in time during this variation, the radar signal reception frequency of the second radar sensor corresponds to the radar signal transmission frequency of the first radar sensor.

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

The advantages and possibilities of further developments already described for the embodiment described above thus result in an analogous manner. For example, it can be provided that during the temporal variation the reception frequency is allowed to vary several times (for example periodically) between predetermined extreme values (for example in a sawtooth shape). A plausibility check can e.g. B. provide a check to determine whether the radar signal transmission works accordingly during the time variation at certain times and / or whether z. B. the time intervals between different points in time of the reception of the radar signal correspond to the expectation (z. B. period of the temporal variation).

In addition, this embodiment, in which the radar signal transmission frequency is not varied in the first radar sensor and instead the radar signal reception frequency is varied in the second radar sensor, has the additional advantage that there are 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 in particular and preferably transmit at 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. Notwithstanding this, but in particular z. B. the ADAS frequency bands 76 GHz - 77 GHz and 77 GHz - 81 GHz can 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 certain frequency band around this frequency (z. B. 24 GHz +/- 10 kHz) should be able to receive and evaluate.

In the case of a radar sensor, e.g. B. a so-called FMCW (“frequency modulated continuous wave”) radar sensor, this should expediently be able to receive and evaluate at least on the same frequency band or a slightly larger frequency band (z. B. 24 GHz +/- 20 kHz).

The term “radar signal reception frequency” refers in the context of the invention to a receiving radar sensor, so z. B. in the data transmission mode on the part of the second radar sensor, intended for the reception and the evaluation based on it.

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 has several reception frequencies or usually (e.g. with CW, especially FMCW radar sensors) an entire frequency band for reception is provided and also an evaluation of the whole Frequency band is performed. As the reception frequency of the radar sensor in this case, for. B. a center frequency of the relevant reception frequency band can be designated.

In the context of the data transmission mode (as well as the possibly provided diagnostic operating mode), the term "radar signal reception frequency of the second radar sensor" denotes the frequency for which the second radar sensor receives and evaluates for the purpose of data transmission (or, if necessary, diagnosis of the transmission path ) is carried out.

In one embodiment it is provided that in the data transmission mode in the case of the second radar sensor, the transmission of a radar signal provided for the detection operating mode is deactivated. In this way, a disturbance in the data transmission caused by a radar signal sent by the second radar sensor can be reliably prevented. In the context of the invention, however, it should not be ruled out that, during the data transmission mode, the second radar sensor is also operated to transmit a radar signal in order to operate this radar sensor (in addition) to detect objects.

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

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

In one embodiment it is provided that in the data transmission mode the evaluation takes into account an intensity of the radar signal received by the second radar sensor in order to quantitatively assess a transmission quality (e.g. channel attenuation) of the transmission path (as part of a diagnosis).

• - 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 aforementioned object is achieved in a radar system of the aforementioned type in that the control device 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:

• - Sending 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 sent 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 provided in an analogous manner as embodiments or special configurations of the radar system according to the invention (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 time intervals and / or z. B. at the same time with the data transmission to effect.

The control device can, for. B. be designed to operate the at least two radar sensors in data transmission mode so that the first radar sensor transmits with a predetermined time-varying radar signal transmission frequency and the second radar sensor receives with a fixed radar signal reception frequency. Alternatively, the control device can, for. B. be designed to operate the radar sensors in data transmission mode so that the first radar sensor transmits with a fixed radar signal transmission frequency and the second radar sensor receives 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 (otherwise provided for the detection operating mode) is deactivated and / or its reception sensitivity is set to be increased.

The control device 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 (operated) radar sensor or sensors in the detection operating mode for the purpose of object detection and, in the data transmission mode, to carry out an evaluation of the radar signal received by the (at least one) second radar sensor for the purpose of demodulating the same ( and thus to recover the data signal or the data contained therein).

The control of the individual radar sensors, be it in detection mode or in data transmission mode, can in particular include activating and deactivating a transmission mode for sending 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 already mentioned time variation of the transmission frequency of the first radar sensor in the 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 already mentioned temporal variation 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 data transmission mode.

In one embodiment of the invention, the radar sensors are each designed to carry out the object detection using the Doppler effect in order to realize an object movement detection (“Doppler radar”). The radar sensors can thus advantageously function as movement sensors, but this does not rule out the possibility that the radar sensors are (additionally) designed and / or operated in a suitable manner for detecting stationary objects.

The Doppler effect is preferably used in that when a radar signal is sent with a certain radar signal transmission frequency, also referred to below as a “TX signal”, a z. B. to this coherent signal is held locally (in the relevant radar sensor), hereinafter also referred to as a 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, what is known as an intermediate frequency signal, also referred to below as an “IF signal”, is created whose time course and its 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, in particular z. B. the time course of the IF signal and / or the spectrum of the IF signal (and / or the time course of this spectrum) can be evaluated. One possible implementation is that the LO signal is coherent with the TX signal. However, in particular for the data transmission mode, no coherence between the LO and TX or RX signals is necessary.

If the LO signal is provided identically to the TX signal, the Doppler shift proportional to the speed of an object (relative to the radar sensor) leads 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.

If an object moves away from the radar sensor, the frequency is Doppler shifted downwards, whereas if the object approaches the radar sensor, the frequency is shifted upwards. By means of 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 thus be detected in a manner known per se.

If the LO signal is provided as a frequency-shifted version of the TX signal, the same applies in principle. 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.

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

The FMCW radar sensor is a possible or more special version of a CW radar sensor. With the FMCW radar sensor, a continuously transmitted TX signal is not transmitted with a fixed radar signal transmission frequency, but a frequency-modulated TX signal is transmitted. For example, a sawtooth-shaped or a sinusoidal or some other periodic frequency modulation can be provided for this. The benefit of the frequency modulation of the TX signal is that the TX signal is given a time stamp at each point in time, so that the runtime of the radar signal (from the radar sensor to the object and again) through a corresponding evaluation of the received radar signal (RX signal) back) and from this the distance between the radar sensor and the object can be determined. With an FMCW radar sensor, both the distance and the speed of objects can thus advantageously be recorded.

One advantage of an FMCW radar, as described, is the ability to determine the distance directly. The speed of an object can alternatively be e.g. B. be determined over 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. Furthermore, a vehicle is proposed which is equipped with such a radar system.

One embodiment provides for use in a parking aid (PDC) of a vehicle. One embodiment provides for the use 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 space doors) in order to monitor the surroundings of the door in question when it is automatically opened (or closed) for safety reasons / or to recognize gestures of a user to initiate such an opening or closing. One embodiment provides for the use for interior monitoring (e.g. alarm system) of a vehicle. One embodiment provides for use for a radar system embodied on a vehicle for gesture recognition (e.g. foot gesture or hand gesture recognition), e.g. B. with radar sensors for foot gesture recognition for the purpose of initiating an automatic door opening (e.g. tailgate opening) and / or automatic door closing.

According to a further aspect of the invention, use of the method described here and / or the radar system described here in an inductive charging station for inductive charging of electrical energy storage devices in vehicles is proposed. Furthermore, an inductive charging station for inductive charging of electrical energy stores of 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 can be designed for (pure) object movement detection.

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

According to a further aspect of the invention, an inductive charging arrangement is proposed, comprising an inductive charging station for inductive charging of 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 to enable data transmission mode, in particular e.g. . B. to be able to transfer data between the inductive charging station and the vehicle during a charging process (e.g. 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.

The data transmission implemented according to the invention is advantageous (at carrier frequencies of, for example, greater than 1 GHz, in particular greater than 10 GHz, and / or, for example, less than 100 GHz, especially less than 90 GHz) less sensitive to interference from the alternating magnetic field generated during the charging (or discharging) process than most of the data transmissions known from the prior art with radio signals between the vehicle and the inductive charging station. With the invention, a robust communication interface can thus be created between the inductive charging station and the vehicle, which functions without problems 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 configured 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 further described below on the basis of 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 exemplary embodiment,
• 3 one each for the radar sensors in the radar system of 1 used signal processing device according to an embodiment,
• 4th Timing diagrams illustrating a detection mode of operation in the radar system of FIG 1 ,
• 5 Timing diagrams illustrating the accomplishment of a data transmission mode in the radar system of FIG 1 ,
• 6th Timing diagrams to illustrate a data transmission,
• 7th a flow chart 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 respectively. TX-2 Receiving a radar signal reflected on an object (not shown) RX-1 respectively. RX-2 and evaluating the received radar signal RX-1 respectively. RX-2 .

The reference numbers of components provided twice in the exemplary embodiment, but having an analogous effect, such as, for. B. the radar sensors 20-1 and 20-2 , are numbered consecutively (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 entirety of such components by the non-supplemented reference number.

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

Any of the radar sensors 20th has a certain detection area in which objects reflecting radar radiation can be detected. In a manner known per se, each of the radar sensors 20th a distance detection and / or a movement detection can be provided in the detection operating mode.

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

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

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

2 shows a radar sensor 20th (one of the radar sensors 20-1 , 20-2 in 1 ), having a voltage controlled oscillator (VCO) 22nd for generating a high-frequency signal which is variable in frequency by means of a control signal c1 and which by means of a branching device 24 is divided into two coherent signals TX and LO. The signal TX serves as a transmission signal from the radar sensor 20th and can be controlled by means of a control signal c2 switching device 26th a transmitting antenna 28 for transmitting the radar signal TX are supplied. The LO signal is used as a local signal from the radar sensor 20th and becomes a first input of a mixer 30th fed. That by means of a receiving antenna 32 received radar signal RX is via a means of a control signal c3 controllable amplifier 34 as a received signal RX to a second input of the mixer 30th fed. At one output of the mixer 30th an intermediate frequency signal IF is output as the resultant signal.

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

3 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 illustrated embodiment, the signal processing device comprises 40 a band pass filter 42 and an analog-to-digital converter 44 in order to subject the intermediate frequency signal IF to a bandpass filtering and to output the signal thus filtered in analog / digital-converted form as the data signal d.

Coming back to 1 will for each of the radar sensors 20-1 , 20-2 the respective data signal d one for both radar sensors 20-1 , 20-2 shared control device 50 fed.

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

4th exemplifies one by means of the control device 50 performed detection mode of operation of the radar system 10 in which the radar sensor 20th ( 2 ) is operated for object detection.

4th above shows a time profile of the control signal c1 (voltage signal) for controlling the oscillator 22nd . In the example shown, a control signal c1 that varies in a sawtooth shape with time t is provided.

4th middle shows a time profile of a frequency fTX of the transmission signal TX and thus that of the radar sensor 20th transmitted radar signal. The frequency fTX also varies in a sawtooth shape by one for the oscillator in accordance with the signal c1 22nd intended center frequency fTX ₀ around.

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

In operation of the radar system 20th these acquisition parameters Δt and Δf can be determined, for example, on the basis of the data signal d. Alternatively, the acquisition parameters could e.g. B. self-sufficient in the respective radar sensor 20th be determined. The time period Δt corresponds to the transit time of the radar signal from the radar sensor 20th to the object and back, from which the 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 the control device 50 thus can determine the speed of the object. In particular if the control device 50 not structurally with the other components of the radar system 10 is summarized, but z. B. is connected via a digital communication bus system (z. B. CAN bus, LIN bus, etc.), the individual radar sensors 20th associated signal processing devices 40 different from the representation in 3 also be additionally designed to initially process the data resulting from the analog-to-digital conversion still further in order to at least partially carry out the evaluation required for object detection and thus e.g. B. the control device 50 and / or to relieve the 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. 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 delay time shift. A differentiation according to object distance / object speed is therefore not possible in this case simply by determining the current frequency of the IF signal.

the 4th shows an example of object detection idealized in so far as the transmitted radar signal is reflected on a single object with a well-defined distance and a well-defined speed and again from the radar sensor 20th Will be received. In real use of the radar system 10 can be used to detect objects using any radar sensor 20th more complicated scenarios also occur. 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 4th shows an example of a detection mode of operation in which the radar sensors 20th be operated as FMCW radar sensors, the radar sensors could deviate from this example 20th can also be operated as CW radar sensors by z. B. the control signal c1 is kept constant (or z. B. is regulated so that the from the oscillator 22nd generated frequency (and thus frequency of the transmission signal TX) is kept constant. In this case, only moving objects would be detected by the radar sensor 20th can be detected (pure "Doppler radar"). Such a CW radar sensor is only sensitive to the speeds of the reflection objects and hides immobile objects. In the automotive sector, Doppler radars are ideal for motion detection in strong reflective environments such as B. in 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 plate ).

In a 24 GHz radar system with radar sensors designed to use the Doppler effect on board a vehicle, the evaluable intermediate frequency range (bandwidth of the signal IF) z. B. extend over less than 5 kHz, in particular less than 1 kHz, since this is sufficient with regard to the speeds of usual 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 for this in a “data transmission mode” of the radar system 10 the two radar sensors 20-1 , 20-2 to operate for a data transmission, whereby the following steps are 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: multiple) radar sensors 20-1 , 20-2 ,
• - Receiving the from the first radar sensor 20-1 transmitted radar signal TXD by a (different, at least one) second radar sensor, here the radar sensor 20-2 , the two radar sensors 20-1 , 20-2 , and
• - Evaluation of the from the second radar sensor 20-2 (as its received signal) received radar signal in order to recover the data signal on the receiver side.

In the example, the data transmission mode can be triggered centrally for all radar sensors involved 20th by means of the control device 50 take place (e.g. via a digital communication bus system such as e.g. CAN bus or e.g. LIN bus).

In the exemplary embodiment shown, the transmission path is advantageously through a “direct line of sight” (for radar signals) between the two radar sensors 20-1 , 20-2 realized, ie the radar signal TXD can be sent directly (without reflection) from the radar sensor 20-1 to the radar sensor 20-2 spread.

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

In the example shown, the first radar sensor is in data transmission mode 20-1 the transmission with a fixed radar signal transmission frequency and with the second radar sensor 20-2 receiving at a predetermined time-varying radar signal reception frequency, so that at least one point in time during this variation the radar signal reception frequency of the second radar sensor 20-2 the radar signal transmission frequency of the first radar sensor 20-1 is equivalent to.

5 illustrates this special feature provided in the example for implementing the data transmission mode in the case of the first radar sensor 20-1 the transmission of the radar signal TXD with a fixed, predetermined radar signal transmission frequency fTXD takes place by the control device 50 the radar sensor 20-1 supplies a constant control signal c1 (or a control signal c1 regulated in such a way that the constant frequency fTXD is thereby brought about).

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

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

The following partial representation of 5 shows a time profile of a frequency caused by the oscillator 22nd generated signal and thus a frequency fLO of a local signal LO branched off therefrom. In accordance with the variation of the control signal c1, the frequency fLO also varies in a sawtooth shape, around a center frequency fLOo. As an alternative to a sawtooth shape, another type of 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, which occurs repeatedly many times during an implementation of the data transmission mode (as below with reference to FIG 6th to be explained).

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

Through a suitable evaluation of the radar sensor 20-2 received radar signal TXD can therefore advantageously z. For example, it can be diagnosed whether the radar signal transmission of the radar signal TXD is functioning via the transmission path or whether this transmission path is impaired. Knowing that the two radar sensors 20-1 , 20-2 are arranged stationary relative to each other and thus their relative speed to each other is zero, this z. B. by the control device 50 The evaluation carried out takes into account that no Doppler shift occurs when the radar signal TXD is transmitted. If the transmission path is functional, it is therefore to be expected that at a specific point in time within each period in the frequency spectrum of the radar sensor 20-2 generated intermediate frequency signal IF at the relevant frequency, ie relevant for a relative speed of zero, 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 the mentioned frequency component. In the example shown, this peak occurs within the period shown at a point in time t _D.

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 or not such a peak occurs as expected, ie in the example shown once per variation period. In the event of the occurrence, the control device assesses 50 with the help of a diagnostic software running in it, that the transmission path works. Otherwise, if the said peak does not occur as expected in the frequency spectrum of the signal IF, the control device evaluates 50 this as an impairment of the transmission path.

The lowest part in 5 shows in a corresponding representation this error case in which the said peak does not occur or only occurs with a greatly reduced intensity. In one embodiment, the control device 50 the peak intensity is recorded in order to make a qualitative assessment of the transmission quality of the transmission path. The lower the peak intensity, the z. B. can be determined on the basis of a peak value and / or an integral of the peak, the lower the transmission quality is rated.

6th illustrated using timing charts similar to those of 5 , but over several periods of the receiver-side variation of the control signal c1 ( 6th middle), the actual data transfer.

6th above shows an example on the transmitter side, ie for the first radar sensor 20-1 Data signal c4 provided for transmission, 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 for this purpose, with in 6th 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 on and off by the first radar sensor 20-1 The transmitted radar signal TXD is used to transmit the data signal c4 to the second radar sensor by means of an “on-off keying” modulation of the radar signal TXD 20-2 transferred to. The data signal c4 is in the first radar sensor 20-1 than the control signal c2 (cf. 2 ) to control the switching device 26th used to signal the TX of the oscillator 22nd depending on the binary value ("0" or "1") of the data signal c4 of the transmitting antenna 28 to be supplied (e.g. with binary value "1") or not (e.g. with binary value "0").

6th below shows the signal Int (IF) resulting in this example within the framework of the evaluation of the radar signal RX at the receiver end with the signals already referring to FIG 5 explained "peaks", whereby these peaks correspond to the periodicity of the signal c1 ( 6th middle) occur periodically, but do not occur in the time phases with the radar signal TXD switched off according to the modulation.

The evaluation of the radar signal RX carried out on the receiver side can therefore interpret the occurrence and absence of the peaks as binary values "1" or "0" in a time pattern corresponding to the periodicity and thus the data signal c4 (in the example: "... 0110101 ..." ) regain, as in 6th shown below.

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

In one step S0 become one or more of the multiple radar sensors 20th operated to detect objects (in particular e.g. as CW radar sensors).

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

After the data transfer mode has been carried out, the radar system changes 10 back to the acquisition operating mode according to step S0 .

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

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

The radar sensors 20-1 until 20-4 are each arranged on the outside of a left front door, a left rear door, a right front door and a right rear door and function in a detection operating mode of the radar system as sensors to ensure safety when the respective vehicle door is automatically opened.

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

In the example shown, when a certain door is intentionally actuated (opening or closing), only the radar sensor assigned to this door is operated for object detection, ie only the radar sensor is operated when the left front door is actuated 20-1 , when the left rear door is operated, only the radar sensor 20-2 etc.

When the radar system is in operation, it changes if necessary (ie when data is pending for transmission), e.g. B. in predetermined "favorable times or intervals", in a data transmission mode to z. B. via one of the radar sensor 20-1 to the radar sensor 20-2 running first transmission path as well as one from the radar sensor 20-3 to the radar sensor 20-4 running second transmission path to be able to carry out a data transmission.

In the example shown, the antenna characteristics of all the transmitting and receiving antennas of the radar sensors are dependent on the spatial angle 20-1 until 20-4 in each case a maximum of the radiation or a maximum of the reception sensitivity in a direction orthogonal to a respective plane the door to use the left radar sensors 20-1 and 20-2 Objects to the left of the associated doors and using the right radar sensors 20-3 and 20-4 Detect objects to the right of the associated doors. It also shows the antenna characteristics of the radar sensors 20-1 until 20-4 a significant (ie sufficient for the data transmission mode) radiation intensity or reception sensitivity in a direction parallel to the plane of the doors (longitudinal direction of the vehicle), so that advantageously direct line of sight for data transmission radar signals exist that are in the data transmission mode from the radar sensor 20-1 to the radar sensor 20-2 and / or vice versa, as well as from the radar sensor 20-3 to the 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 FIG 8th in front of side doors of a vehicle, advantageously z. B. an exposed (protruding from a vehicle outer skin) installation position of the radar sensors can be provided, for. B. on or in door handles. Alternative mounting or installation positions on the vehicle are z. 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 until 20-4 can e.g. B. corresponding main lobes and side lobes in their antenna characteristics, or z. B. more or less evenly a semicircle or a hemisphere covering antenna characteristics.

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

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

The example shown shows the antenna characteristics of all the transmitting and receiving antennas of the radar sensors 20-1 until 20-4 a radiation intensity or reception sensitivity in all lateral directions (360 ° antenna characteristic), so that all radar sensors are in a detection operating mode of the radar system 20-1 until 20-4 at the same time as object detection in the respective, in 9 to operate the detection areas shown in dashed lines.

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

Notwithstanding the use of the in 9 shown and with the radar sensors 20-1 until 20-4 Equipped floor plate as a component of the "stationary" part of an inductive charging arrangement for vehicles is also possible to provide a similarly configured (ie equipped with several radar sensors) floor plate or the like as a component of the "mobile" part of an inductive charging arrangement, ie in a vehicle underbody of a vehicle to be built in. In this case, the vehicle itself is equipped with a radar system (as an alternative or in addition to the inductive charging station), which advantageously also enables object detection, in particular for the purpose of so-called "living object detection", and which also advantageously allows data to be transmitted within the vehicle's radar system can.

It is advantageous within the scope of the invention in the application of inductive charging also 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, 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, a data transmission between the vehicle (or a vehicle currently located at the charging station) and the charging station can also take place particularly advantageously. An example of such an inductive charging arrangement is described below with reference to FIG 10 described.

10 shows one with a radar system 10 the type described here equipped inductive charging arrangement 3 by an inductive charging station 2 ("Stationary part") and a vehicle (while it is being charged or discharged at the inductive charging station) 1 ("Mobile part") is formed.

The inductive charging station 2 includes for inductive charging of the vehicle 1 a loading unit 4th containing a coil 5 (Primary coil when charging). For charging the vehicle 1 this is initially as in 10 shown in this way in the area of the inductive charging station 2 parked that one in a loading unit 7th of the vehicle 1 located coil 8th (Secondary coil when loading) in a suitable position with respect to the coil 5 got. In the example there is the coil 8th z. B. approximately coaxially above the coil 5 . In this arrangement situation, a charging control unit on the station side (and supplied with electrical energy) can then be used by means of a corresponding control 14th electrical power from the coil in a known manner 5 over a transmission range 9 to the coil 8th be transmitted.

In 1 The field lines of the coil are shown in dashed lines 5 generated magnetic alternating field, which in the coil 8th an alternating voltage is induced via a charging control unit in the vehicle 11 rectified to an on-board electrical system 12th , containing, among other things, an electrical energy store, is supplied. Based on the on-board network 12th can in operation of the vehicle 1 electrical energy, for example to supply a drive device 13th of the vehicle 1 be used. In the example shown, the loading unit has 4th the shape of a "floor slab", which is embedded in the ground or a drivable foundation sunk in the ground. The floor level is marked with B.

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

The radar system 10 includes four radar sensors in the example 20-1 until 20-4 on the station-side loading unit (base plate) 4th and another four radar sensors 20'-1 until 20'-4 on the vehicle-side loading unit 7th . This means that data can also be transmitted from the vehicle in particular 1 to the charging station 2 and / or vice versa, for which one of the radar sensors is used as the “first” and “second” radar sensors to be used in the data transmission mode 20-1 until 20-4 and one of the radar sensors 20'-1 until 20'-4 are to be selected and operated accordingly.

Claims (13)

Method for operating a radar system (10), the radar system (10) having at least two radar sensors (20-1, 20-2) for a respective object detection by sending 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, characterized in that the method further provides a data transmission mode, having the following steps: - sending 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 from 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 - evaluation of the radar signal (T XD) in order to recover the data signal (c4). Procedure according to 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 Claims 1 until 2 , wherein in the data transmission mode the first radar sensor (20-1) transmits with a predetermined time-varying radar signal transmission frequency and the second radar sensor (20-2) receives with a fixed predetermined radar signal reception frequency, so that at least one point in time during 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) to this variation. Method according to one of the Claims 1 until 2 , wherein in the data transmission mode the first radar sensor (20-1) transmits with a fixed predetermined radar signal transmission frequency (fTXD) and the second radar sensor (20-2) receives 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). Method according to one of the preceding claims, wherein in the data transmission mode the second radar sensor (20-2) is deactivated for the transmission of a radar signal (TX-2) provided for the detection operating mode. Method according to one of the preceding claims, wherein, in the data transmission mode, the reception by the second radar sensor (20-2) takes place with a reception sensitivity set higher than that in the detection operating mode. Method according to one of the preceding claims, wherein in the data transmission mode the Evaluating an intensity of the radar signal (TXD) received by the second radar sensor (20-2) is taken into account in order to quantitatively assess a transmission quality of a transmission path running from the first radar sensor (20-1) to the second radar sensor (20-2). Radar system (10), comprising at least two radar sensors (20-1, 20-2) for a respective object detection by sending 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 in a detection operating mode of the radar system (10), characterized in that the control device (50) is also designed to do so to operate the at least two radar sensors (20-1, 20-2) for a transmission of data in a data transmission mode of the radar system (10), the following steps being carried out in the data transmission mode: transmission of a radar signal modulated based on a data signal (c4) (TXD) 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 recover the data signal (c4). Radar system (10) Claim 8 , 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) Claim 8 or 9 , 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 the Claims 8 until 10 . Inductive charging station (2) for inductive charging of electrical energy storage devices in vehicles (1), the inductive charging station (2) having a radar system (10) according to one of the Claims 8 until 10 Is provided. Inductive charging arrangement (2, 1), having an inductive charging station (2) for inductive charging of electrical energy storage devices of vehicles, and a vehicle (1) with an electrical energy storage device, the inductive charging arrangement (2, 1) having a radar system (10) according to one of the Claims 8 until 10 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).

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