Radar sensor device and method of operating a radar sensor device

Abstract

The present invention relates to a radar sensor device (10) comprising at least one radar sensor (RS1) and a control device (SE) connected to the at least one radar sensor (RS1) and configured to control the generation of the transmission signal and the scanning of the received signal of the radar sensor, wherein the transmission signal is a linearly frequency-modulated signal that is periodically repeated, and the center frequency and / or ramp gradient and / or pulse repetition rate of the transmission signal, and / or the number of frequency ramps per measurement cycle and / or the pause between measurement cycles are adjustable, and the control device is configured to detect a pulsed interference occurring in the scanned received signal and calculate the frequency of the transmission causing the interference.

Description

Technical Field

[0001] The present invention relates to a radar sensor device and an operating method of the radar sensor device.

Background Art

[0002] Radar sensors can play an important role in increasing the degree of vehicle automation, and the number of radar sensors per vehicle is expected to further increase. In general applications, many vehicles may already be equipped with driving assistance functions realized using radar sensors. A radar sensor transmits a modulated electromagnetic wave and determines the distance and relative speed of various reflection points around a moving vehicle from the received reflection that is delayed and Doppler frequency shifted.

[0003] Currently, serial sensors of different vehicles use independent modulations, and usually the wavelengths are not adjusted to each other. As a result, the signals of the radar sensors interfere due to the overlap of electromagnetic waves, and the probability of signal quality degradation increases simultaneously.

[0004] Since the number of radar sensors in a vehicle is increasing, in order to reduce the interference of the radar sensors of the vehicle, the radar sensors operate in cooperation. For this purpose, the radar sensors are synchronized on the hardware side.

[0005] M.B.A1abd, B.Nuss, C.Winkler and T.Zwick, "Partial Chirp Modulation Technique for Chirp Sequence based Radar Communications (Partial Chirp Modulation Technique for Radar Communications Based on Chirp Sequences)", 2019 16th European Radar Conference (EuRAD), 2019, pp. 173 - 176. describes an application example of a modulation method.

[0006] European Patent Application Publication No. 3572828 describes a system combining radar and communication.

Prior Art Documents

Non-Patent Literature

[0007]

Non-Patent Literature 1

Patent Literature

[0008]

Patent Literature 1

Summary of the Invention

Means for Solving the Problems

[0009] The present invention provides a radar sensor device according to claim 1 and an operating method of the radar sensor device according to claim 6. Preferred improvement forms are the subject matter of the dependent claims.

Effects of the Invention

[0010] The idea underlying the present invention is to describe a radar sensor device and an operating method of the radar sensor device, which can better select the operation of scanning the radar sensor at specific times and signal waveforms. Here, the scanning means receiving a high-frequency signal transmitted from the radar sensor, and this high-frequency signal is characterized as a linear frequency modulation, i.e., a frequency ramp over time. In the receiver, the signal received by the antenna system is mixed down to the baseband with the transmitted signal and scanned by an analog-to-digital converter.

[0011] According to the present invention, a radar sensor device includes at least one radar sensor and a control device connected to the at least one radar sensor, configured to apply a transmission signal to the radar sensor and execute a scanning sequence in the radar sensor. In order to apply the scanning sequence, a specific period of the transmission signal and / or the reception signal in the radar sensor can be selected.

[0012] According to the present invention, a radar sensor device includes at least one radar sensor and a control device connected to the at least one radar sensor, configured to control the generation of the transmission signal of the radar sensor and the scanning of the reception signal. The transmission signal is a linearly frequency-modulated signal that is periodically repeated, and the center frequency and / or the ramp slope and / or the pulse repetition rate of the transmission signal, and / or the number of frequency ramps per measurement cycle and / or the pause between measurement cycles are adjustable. The control device is configured to detect a pulsed interference occurring in the scanned reception signal and calculate the frequency of the transmission that causes it.

[0013] According to a preferred embodiment of the radar sensor device, the transmission that causes the interference is related to another radar sensor and is performed from that radar sensor. According to a preferred embodiment of the radar sensor device, the radar sensor device includes a reference control unit and a reference sensor configured to transmit a reference transmission signal. The control device is connected to the radar sensor, and the transmission signal of the radar sensor can be synchronized with the reference transmission signal of the reference sensor regarding the transmission and scanning by the control device.

[0014] According to a preferred embodiment of the radar sensor device, the transmission signal includes a triangular signal. According to a preferred embodiment of the radar sensor device, a reference unit including a reference control unit and a reference sensor, and a further sensor unit including a control device and a radar sensor are in different vehicles.

[0015] A (specified) scanning sequence can evaluate the received signal from a radar sensor and make inferences regarding the distance and movement of an object. The scanning points and / or transmission points in frequency and time can be advantageously selected, for example, at specific times and frequencies of the signal, for example, also in terms of numbers and durations and / or the like. The change in frequency can be a specific type of frequency waveform at the selected scanning point, for example, a section where the frequency of the signal ramp increases (e.g., linearly or non-linearly), or decreases, or both.

[0016] Accordingly, the sign of the ramp slope (ramp direction) of the lamp can be changed during scanning, or scanning can be performed when the gradient of the signal is as desired. That is, scanning can also be selected in the signal section within the "chirp sequence" measurement cycle. A particular advantage is that this method is simple and can be used immediately without affecting subsequent signal processing. A desired signal can be set and the section to be scanned can be selected.

[0017] The ramp direction within the measurement cycle can be arbitrarily selected, providing various possibilities for the radar sensor. In this way, since triangular wave modulation can be used with substantially constant signal processing, there is no need for a return in the phase control loop, and the repetition rate of the ramp can be increased. By omitting the return, interference is reduced and there is no need to switch off the transmission amplifier. Furthermore, since cooperative sensors can be synchronized, transmission can be adjusted wirelessly to avoid interference. Additionally, communication between radar sensors becomes possible by selecting the ramp direction according to an information data stream (e.g., a series of 0 and 1 symbols). This can be used to adjust the communicating radar sensors and exchange information.

[0018] According to a preferred embodiment of the radar sensor device, the radar sensor device includes a reference sensor in which a reference transmission signal is transmitted and / or a reference scanning signal is used, and a control device that controls the reference transmission signal and the reference scanning signal with respect to time, frequency, and ramp direction.

[0019] Furthermore, the operation adjustment between multiple radar sensors or the synchronization of the operation or scanning of the radar sensor can be improved. According to a preferred embodiment of the radar sensor device, a predetermined transmission signal includes a triangular signal, and preferably includes a triangular signal that is a function of time of the frequency of the transmission signal.

[0020] The transmission signal can preferably be variable and thus can be adapted / synchronized to a reference signal and / or a reference scanning rate. According to a preferred embodiment of the radar sensor device, the scanning can be performed during the frequency increase signal ramp of the transmission signal and / or the reception signal, and / or during the frequency decrease signal ramp of the transmission signal and / or the reception signal, and / or the gradient of the signal ramp can be selected by the control device.

[0021] According to a preferred embodiment of the radar sensor device, the radar sensor device includes a plurality of radar sensors that can be installed on the same vehicle or particularly different vehicles, and the transmission signals and scanning sequences in these radar sensors can be synchronized with a reference scanning signal and a reference transmission signal by the plurality of radar sensors.

[0022] In addition to synchronization, communication between radar sensors can be performed via an air interface. According to the present invention, a method for operating a radar sensor device includes providing a radar sensor device according to the present invention including at least one radar sensor and a reference sensor; detecting a pulse interference generated in the reception signal of the radar sensor by the transmission of the reference sensor and calculating the transmission frequency of the transmission of the reference sensor; and driving and controlling the radar sensor by a control device such that the detected frequency of the frequency generated by the reference sensor in the reception signal of the radar sensor becomes constant by appropriate adjustment of modulation parameters, particularly the center frequency, ramp gradient, and transmission time.

[0023] According to a preferred embodiment of the present method, the transmission from the radar sensor is synchronized with the transmission from the reference sensor, and the control device drives and controls the radar sensor in a sequence of ramp slopes suitable for minimizing the duration of the amplitude pulse interference and thus the interference.

[0024] According to a preferred embodiment of the present method, further, the control device drives and controls the radar sensor in a sequence of ramp slopes suitable for generating a series of amplitude pulse interferences for transmitting a notification based on a predefined codebook in the received signal of the reference sensor.

[0025] According to a preferred embodiment of the present method, further, in connection with the control device driving and controlling the radar sensor in a sequence of ramp slopes having an appropriate time offset with respect to the transmission from the radar sensor to avoid or reduce the interference generated by the reference sensor in the received signal of the radar sensor, the interference of the notification in the radar sensor is minimized.

[0026] According to a preferred embodiment of the present method, further, in connection with the control device driving and controlling the radar sensor in a sequence of ramp slopes having an appropriate frequency offset with respect to the transmission from the reference sensor, particularly to avoid or reduce the interference generated by the reference sensor in the received signal of the radar sensor, the interference of the notification in the radar sensor is minimized.

[0027] According to a preferred embodiment of the present method, the reference sensor transmits a notification for adjusting the transmissions of various radar sensors by transmitting an appropriate lamp sequence after synchronizing and transmitting the notifications from the plurality of radar sensors, and the control device of the radar sensor interprets the notification according to a predefined codebook.

[0028] According to the present invention, in the operating method of a radar sensor device, there are steps of providing a radar sensor device according to the present invention, driving and controlling the radar sensor with a transmission signal, and executing a scanning sequence on the radar sensor, and for applying the scanning sequence, a specific period of the transmission signal and / or the reception signal is selected.

[0029] According to a preferred embodiment of the method, the signs of the ramp gradients of the transmission signal and / or the reception signal and / or the scanning sequence are selected according to set values. According to a preferred embodiment of the method, a reference sensor transmits a reference transmission signal for a second (or further) radar sensor to synchronize its own transmission signal using a control device.

[0030] According to a preferred embodiment of the method, the reference sensor generates a reference transmission signal and / or a reference scanning signal, and these are used by the second sensor using its control device to synchronize the transmission signal of the second sensor with respect to transmission and scanning to the reference transmission signal of the reference sensor.

[0031] The presented method is easy to implement and can be technically directly applied to current radar sensors. However, due to the current regulations of the radar frequency band, the communication with the radio positioning service is separated, so this method is considered to be particularly suitable for future sensors in new frequency bands such as, for example, above 100 GHz. The expansion of the speed evaluation range brings advantages to the sensor itself, and the reduction of interference brings advantages to all radar sensors used.

[0032] The radar sensor device can also be characterized by the features and advantages described in relation to the method, and vice versa. Further features and advantages of embodiments of the present invention will become apparent from the following description with reference to the accompanying drawings.

Brief Description of the Drawings

[0033] The present invention will be described in more detail below with reference to the embodiments shown in the schematic diagrams of the drawings.

Figure 1

Figure 2

Figure 3

[0034] In the figures, the same reference signs denote the same or functionally identical elements.

Mode for Carrying Out the Invention

[0035] FIG. 1 is a schematic diagram of signal waveforms for operating a radar sensor device according to a comparative example and two embodiments of the present invention. In FIG. 1, a ramp signal (transmission signal or reception signal) of frequency f is shown according to time t, which corresponds to a conventional chirp signal. The scanning is usually performed only on the frequency down-branch via the scanning point di.

[0036] The sawtooth "chirp sequence" modulation method shown in FIG. 1a can be assumed to be the prior art. FIG. 1a shows the modulation method on the rising ramp of the signal frequency in the radar sensor and the shown scanning point di. After a two-dimensional scan in the time direction and the frequency direction, the distance (via time delay) and speed (via Doppler frequency shift) of the radar target can be determined (for example, when the transmission signal and the reception signal are superimposed).

[0037] In contrast, FIGS. 1b and 1c follow an approach that has the advantage of being able to be used in a form that adapts the "chirp sequence" modulation method without affecting radar signal processing. Instead, the application of modulation is improved, resulting in further applicability, for example, in the synchronization and communication of cooperating radar sensors. In a typical chirp sequence radar, the generated transmission signal (a frequency ramp with frequency dependence f(t)) is simultaneously used as the input signal to the mixer in the receiving path (homodyne principle). After the mixer, the received signal is filtered by an anti-aliasing filter (AAF) with a low-pass filter of cut-off frequency fAAF. Thereafter, the signal is scanned by an A / D converter.

[0038] According to the homodyne principle, the frequency band sensitive to signal reception is effectively shifted together with f(t). The sign of the individual ramps of the signal in the radar sensor can be changed within the measurement cycle. In other words, the frequency waveform of the radar transmission signal can follow a specific sequence with positive or negative gradients, and ramps (or multiple ramps) that can also be paused can be selected.

[0039] When inverting the ramp direction without affecting signal processing, the scanning of the frequency ramp needs to be adapted such that, as shown in FIG. 1b, the scanned values correspond to the same instantaneous frequency of the ramp, i.e., even for a ramp with decreasing frequency, the scanning points have the same time step width.

[0040] In a system consisting of two radar sensors (a reference sensor or a first sensor and a second sensor), the second sensor operates with a sequence complementary to that of the first sensor. That is, while the reference sensor uses a signal with increasing frequency over time, the second sensor uses a signal with decreasing frequency over time.

[0041] Both the first sensor and the second sensor detect the scanned values in the received signal that has been interfered with by other sensors. Interference is generated by receiving high-frequency signals transmitted by other sensors. The interference appears as amplitude pulse interference in the scanned received signal. This pulse interference is associated with a specific frequency in the receiver (Figure 3).

[0042] In particular, the second sensor detects the scanned value that has been disturbed (interfered with) as amplitude pulse interference by the signal from the first sensor. In the "Chirp Sequence" method of Figure 1a, the scanned value of the interference of the signal of the first sensor in the second sensor that is fully synchronized (having a sequence complementary to the first sensor with respect to the ramp gradient) is preferably in the middle of the frequency span swept by the frequency ramp for each chirp at the same frequency. In this case, the start times of the frequency ramps of the first sensor and the second sensor are synchronized.

[0043] During the radar channel, i.e., during the period of a ramp (for example, a sub-interval of a rising ramp or a falling ramp), it can be assumed that the signal reflected by the object is temporally constant with respect to the frequency within the baseband, and only the order of the scanned values needs to be inverted for the ramp in the opposite direction. This method does not affect subsequent signal processing.

[0044] As applicable in Figure 1a, since there is no going back to the beginning of the rising ramp (the new scanning sequence starts again with the rising ramp, and the frequency scanned value returns to the minimum value of the scan in the known method, but in the method steps according to the present invention, such a return can be omitted), firstly, the repetition rate of the ramp can be increased, whereby the measurable speed is significantly increased. Secondly, this reduces the possibility of interference and the switch-off of the transmission amplifier when the ramp returns can be omitted.

[0045] Furthermore, according to Figure 1c, a different series of regions of the rising region, falling region, or stationary region of the signal can be used, which follow each other, and this change in the ramp direction can be understood as binary coding (for example, the rising ramp corresponds to 1, and the falling ramp corresponds to 0. Refer to the code 1101 in Figure 1c).

[0046] The meaning assigned to this code can be used to intentionally transmit information. Here, it should be noted that the time to return should consider that there is a certain repetition rate of the lamp.

[0047] Thus, the encoding of the lamp direction can also be used for data transmission between radar sensors. When synchronization is performed between the first sensor and the second sensor, based on the temporal position of the pulsed interference, it is possible to identify whether the received interference signal is a rising ramp or a falling ramp.

[0048] The pulsed interference in the received signal is caused by the transmission signal of the first sensor having a frequency dependence fsi(t) crossing the frequency range of the second sensor that senses reception with a cut-off frequency fs2(t) ± fAAF,2. This signal appears as a pulsed interference in the scanned baseband signal.

[0049] The actual frequency of the interference can be calculated from the temporal position of the interfered scanned value and fs2(t). Subsequently, decoding is performed and it can correspond to simple interference detection on the receiving side.

[0050] The pulsed interference caused by this communication can be limited to some scanned values of the scanning sequence, and after decoding using conventional methods, it can be appropriately corrected by appropriate filtering or replacing the interfered scanned values with estimated values.

[0051] As described above, by assigning meaning to the encoded sequence of rising and falling ramps used by the first sensor, it is possible to transmit any information that can be used to improve the cooperation of radar sensors. For example, the ID (identification) of the function executed by the radar sensor, the prioritization regarding the frequency band, the identification of the sensor type, and the transmission of the center frequency and bandwidth used are also considered.

[0052] During communication, that is, during data transmission between radar sensors, by comparing the time of the predicted interference pulse with the time of the actual interference pulse, the synchronization of a series of frequency ramps of both sensors can be re-controlled (corrected, improved, adapted), and the difference functions as the control amount of the digital control of the signal output of the ramp sequence.

[0053] Figure 2 is a block diagram of the method steps of an operating method of a radar sensor device according to a further embodiment of the present invention. In the operating method of the radar sensor device, the radar sensor device according to the present invention is provided S1, the radar sensor is driven and controlled by a transmission signal S2, a scanning sequence is executed on the radar sensor, and a specific period of the transmission signal and / or the reception signal is selected to apply the scanning sequence.

[0054] Figure 3 is a diagram of the interference signals from fully synchronized radar sensors and their deviations. This method can be used for the synchronization of cooperative radar sensors. Here, "cooperative" can mean that the radar sensors are connected to each other in some way and / or their operating modes are adjusted to each other. For this purpose, a reference sensor and a fixed bit sequence of the transmission signal and / or the scanning signal can be determined in advance, and the reference sensor transmits and measures with this sequence known to all other sensors. The radar sensors to be synchronized use, for example, an inversion code as shown as 0100 in Figure 1c.

[0055] When the measurement cycles are fully synchronized, as shown in Figure 3a, pulsed interference Int may occur in the middle of all lamp or baseband signals. The frequency constant line Int indicates that the pulsed interference occurs at the same point (time or frequency associated with the lamp function) for all lamps of the second sensor. This "same point" is preferably at the center of the lamp of the second signal. Thereby, time and frequency are fully synchronized. The lamps of the first sensor and the second sensor are preferably orthogonal to each other as increments, which corresponds to complete synchronization. As shown in Figure 3b, if there is a deviation (such as when the lamps are tilted from waveforms orthogonal to each other), the lamps can be corrected and synchronized.

[0056] When the interference is distributed towards the upper and lower ends (i.e., towards higher and lower frequency values), as shown in Figure 3b, there is no longer synchronization and it can be detected by conventional interference detection methods. The length of the pulse deviated from the interference signal can be coded for any behavior depending on the error in correcting the synchronization (time shift of the signal fS2(t) or time stretch of the signal fS2(t)). The shifted bar of the signal Int can represent the frequency position of the generated pulsed interference, and in this case, it is not synchronized. The width of each interference pulse can be the degree of the lamp gradient of the interference signal. This feature can also be used to classify the desired pulse sequence of the synchronized sensors, and the sequence of the rising and falling lamps of the first sensor can be estimated. When the deviation of the interference maximum value is detected as a control difference (when the bar Int is shifted from the horizontal center), the synchronization becomes a simple control task. When the interference occurs only sporadically, the measurement cycles are not yet superimposed, and it is necessary to restore approximate synchronization, for example, by delay.

[0057] For synchronization, the sensors to be synchronized switch to their original code, i.e., the code optimal for their own function (the code of the second sensor), and an additional delay, in particular a predetermined deviation from a specified reference signal, is taken into account. Since the sensors can always send mutual pauses to each other, they are not disturbed. When synchronization is performed, the second sensor (e.g., its control device) can know when the first sensor is not transmitting, and intentionally goes into a pause, where it can then select a sequence of rising and falling ramps optimally for its measurement task.

[0058] For example, in the case of two sensors, sawtooth modulation can be used for synchronization (1111 and 0000). Due to the drift of the time interference pulse (the intersection when signals are superimposed in the time-frequency diagram), the deviation can be detected better by changing the ramp direction. Equalization of the ramp clocks between the reference sensor and the radar sensor can be done by inserting additional pauses into the ramp sequence. Furthermore, different codes may be used for the sensors to be synchronized in order to synchronize multiple sensors.

[0059] By reducing interference signals not originating from the sensors to be synchronized, the robustness of the described method can be increased. The interference signals can be associated with individual sensors by identifying them and appropriately classifying them according to signal strength. For this purpose, advantageously, only interference signals with sufficiently similar amplitudes are used.

[0060] For signal filtering, the correlation between the interference pulse train and the expected code (e.g., prior knowledge from a so-called codebook that defines the code used by the communication / cooperating sensors) can be used to filter only the pulses desired for synchronization.

[0061] According to the homodyne principle, the width of each interference pulse can be the degree of the ramp gradient of the interference signal. This is because the frequency ramp of the first sensor generates a wider interference pulse at the second sensor as its ramp gradient approximates that of the first sensor. Advantageously, this feature can be used to classify the desired pulse sequence of the synchronized sensors.

[0062] As described above, the present invention has been fully described based on the preferred embodiments, but the present invention is not limited thereto and can be variously modified.

Claims

1. - at least one radar sensor (RS1); - a control device (SE) connected to the at least one radar sensor (RS1) and configured to control the generation of the transmission signal and the scanning of the reception signal of the radar sensor; comprising wherein the transmission signal is a linearly frequency-modulated signal that is periodically repeated; wherein the center frequency and / or ramp slope and / or pulse repetition rate of the transmission signal, and / or the number of frequency ramps per measurement cycle and / or the pause between measurement cycles are adjustable; wherein the control device is configured to detect pulsed interference occurring in the scanned reception signal and calculate the frequency of the transmission that causes it; a radar sensor device (10).

2. wherein the transmission that causes the interference relates to another radar sensor and is performed from that radar sensor, the radar sensor device (10) according to Claim 1.

3. Reference control unit (SE ｒｅｆ ), and a reference sensor (Ref) configured to transmit a reference transmission signal, wherein the control device (SE1) is connected to the radar sensor (RS1), and the transmission signal of the radar sensor (RS1) can be synchronized with the reference transmission signal of the reference sensor regarding transmission and scanning by the control device (SE1). The radar sensor device (10) according to claim 1 or 2.

4. The radar sensor device (10) according to any one of Claims 1 to 3, wherein the transmission signal includes a triangular signal.

5. The reference control unit (SE ｒｅｆ ), and the reference sensor (Ref), a reference unit (SE ｒｅｆ and Ref), and the control device (SE), and the radar sensor (RS1), a further sensor unit, are in different vehicles, the radar sensor device (10) according to claim 3.

6. - providing a radar sensor device (10) according to any one of Claims 1 to 5, comprising at least one radar sensor (RS1) and a reference sensor (Ref) (step S1); - detecting pulse interference occurring in the reception signal of the radar sensor (RS1) by the transmission of the reference sensor (Ref) and calculating the transmission frequency of the transmission of the reference sensor (Ref) (step S2); - driving and controlling the radar sensor (RS1) by the control device (SE1) such that the detected frequency of the frequency generated by the reference sensor (Ref) in the reception signal of the radar sensor (RS1) becomes constant by appropriate adjustment of modulation parameters, particularly the center frequency, ramp slope, and transmission time (step S3); A method of operating a radar sensor device (10).

7. - synchronizing the transmission from the radar sensor (RS1) with the transmission from the reference sensor (Ref); - driving and controlling the radar sensor (RS1) by the control device (SE1) in a sequence of ramp slopes suitable for minimizing the duration of the amplitude pulse interference and thus the interference; The method according to Claim 6, further comprising.

8. - The control device (SE1) further performs a step of driving and controlling the radar sensor (RS1) in a sequence of ramp gradients suitable for generating a series of amplitude pulse interferences for transmitting a notification based on a specified codebook in the received signal of the reference sensor. The method according to claim 6 or 7.

9. - In connection with driving and controlling the radar sensor (RS1) by the control device (SE1) in a sequence of ramp gradients having an appropriate time offset with respect to the transmission from the reference sensor (Ref) in order to avoid or reduce interference generated by the reference sensor (Ref) in the received signal of the radar sensor (RS1), a step of minimizing the interference of the notification in the radar sensor (RS1) is further performed. The method according to claim 8.

10. - In connection with driving and controlling the radar sensor (RS1) by the control device (SE1) in a sequence of ramp gradients having an appropriate frequency offset with respect to the transmission from the reference sensor (Ref), particularly in order to avoid or reduce interference generated by the reference sensor (Ref) in the received signal from the radar sensor (RS1), a step of minimizing the interference of the notification in the radar sensor (RS1) is further performed. The method according to claim 8 or 9.

11. The reference sensor transmits a notification for adjusting the transmissions of the various radar sensors by transmitting an appropriate lamp sequence after synchronization and transmission of notifications from a plurality of radar sensors (RS1, RS2, RS3), and the control device of the radar sensor interprets the notification according to a pre-specified codebook. The method according to any one of claims 8 to 10.

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