RADAR SENSOR HEAD FOR A RADAR SYSTEM

Description

[0001] The invention relates to a radar sensor head for a radar system. The invention further relates to a radar system. State of the art

[0002] The published patent application DE 10 2007 045 561 A1 discloses a driver assistance system.

[0003] The published patent application DE 10 2012 220 311 A1 discloses a method for detecting sensor degradation in distance sensors.

[0004] The published patent application EP 2 090 897 A1 discloses a driver assistance system of a vehicle.

[0005] The published patent application DE 10 2012 024 880 A1 discloses a method for determining the authenticity of an ultrasonic sensor of a motor vehicle.

[0006] The published patent application EP 3 165 944 A1 discloses a radar communication method.

[0007] The published patent application WO 2015 / 176884 A1 discloses a parking assistance device for a motor vehicle.

[0008] The published patent application EP 2 455 779 A1 discloses an ultrasound-based direction determination of objects in a vehicle environment.

[0009] Vehicles with a high level of driver assistance functions or automated driving functions are increasingly being equipped with radar sensors. A larger number of radar sensors is intended to achieve higher performance of automated or semi-automated functions compared to individual radar sensors. Previous solutions in this area consist of radar sensors that perform extensive internal data processing of the received radar waves. This allows the radar sensors to provide object- or location-level data for further analysis by the vehicle. This can reduce the amount of data transmitted to the vehicle, but requires the respective radar sensors to have greater computing power and larger memory.

[0010] The disadvantage here is that the computing power and memory size are relatively unfavorable in terms of increased performance. This results in particular from the fact that, starting from a defined performance requirement, microcontroller technology is no longer sufficient for the necessary processing steps of the received radar waves. Therefore, to increase performance, the necessary calculations and analyses must be performed internally within the sensor using microprocessor technologies. This can have a negative impact on the price, size, and power losses of a radar sensor. Disclosure of the invention

[0011] The object underlying the invention can be seen in proposing a radar sensor head for a radar system which is inexpensive and flexibly scalable with regard to the number of elements used.

[0012] This object is achieved by means of the respective subject matter of the independent claims. Advantageous embodiments of the invention are the subject matter of the respective dependent subclaims.

[0013] According to a first aspect, the object is achieved with a radar sensor head for a radar system having the features of claim 1, comprising: at least one transmitting antenna for generating and at least one receiving antenna for receiving radar waves; an interface for connecting the radar sensor head to a data line; and an identification unit for identifying the radar sensor head, wherein the identification unit can be used to initiate a download of calibration data from the sensor head to a central control device.

[0014] In the radar sensor head according to the invention, an already required authentication according to the invention is thus combined with a download of required calibration data to the central control unit. The calibration data correspond to the respective radar sensor head and are essential for the proper functionality of the radar sensor head. This advantageously saves storage space in the radar sensor head for the calibration data. This advantageously supports the fact that a sensor head manufacturer can upload the calibration data to the server, which can then be downloaded to the central control unit as needed (e.g., during a workshop visit). This supports simple installation and maintenance of radar sensor heads.

[0015] In this way, a partitioning of the entire system by providing a radar sensor head is advantageously enabled.

[0016] Today's radar sensors are often designed as fast-chirp radars. This means that many fast FMCW (Frequency Modulated Continuous Wave) ramps are transmitted into a scanning area, which is also referred to as a chirp sequence or a rapid chirp method. After the received radar signals are mixed, the baseband signals are filtered, digitized, and generally subjected to a 2D Fourier transform. Since a subsequent Doppler FFT (Fast Fourier Transform) can only take place once the data or measurement signals from all ramps or frequencies have been processed, a large memory is required to buffer the received radar signals. Furthermore, the high latency requirements require high computing power, which is why hardware accelerators are typically used.

[0017] Given that multiple radar sensors are deployed in a vehicle, it is advantageous to concentrate the required computing power in at least one central control unit. The respective radar sensors can thus be designed as compact and inexpensive radar sensor heads without significant power losses. This allows for a better overall price-performance ratio and increased radar system performance.

[0018] A proposed radar sensor head comprises components for generating and transmitting radar waves, as well as components for receiving and processing received radar waves. The processing of the received radar waves is limited to the minimum possible extent or takes place with the least possible effort. In particular, the measurement data of the received radar waves can be digitized by the analog-to-digital converter and subsequently transmitted with a high bandwidth to the at least one central control unit. The further processing of the digitized measurement data from the at least one radar sensor head can then take place in the central control unit.

[0019] This allows the costs for the respective radar sensor heads to be reduced, as less computing power is required in the radar sensor heads. Furthermore, lower power losses can occur in the respective radar sensor heads due to the fewer processing steps. Although the computing effort in the at least one central control device increases, the computing power can be scaled more easily or with less effort compared to the costs incurred. When considering the radar system as a whole, the radar system according to the invention can be expanded and scaled inexpensively and flexibly compared to previous solutions. Furthermore, the higher computing power of the at least one central control device allows more complex and powerful algorithms to be used to process the received radar waves.

[0020] With increasing high-level integration, it is also possible to integrate a first processing stage into a high-frequency component, such as a so-called Monolithic Microwave Integrated Circuit (MMIC). This can preferably be an analysis unit for performing Fourier analysis.

[0021] For example, the analysis unit can perform a range FFT on the digitized measurement data. Depending on the modulation method used, other Fourier transforms can also be applied. This first processing stage can usually be integrated inexpensively into the existing components of a radar sensor head, as the required area in the radio-frequency component is very small and the memory requirements are low. Thus, the silicon area used in the corresponding radio-frequency component can usually remain the same.

[0022] A preferred embodiment of the radar sensor head is characterized in that it further comprises a preprocessing unit for the defined preprocessing of received data. This advantageously provides greater system integration within the radar sensor head.

[0023] Another preferred embodiment of the radar sensor head is characterized in that the calibration data can be updated using the identification unit. This supports, for example, the radar sensor head remaining in the system, but new functionalities being implemented that are only possible with new calibration data.

[0024] A further preferred embodiment of the radar sensor head is characterized in that the calibration data can be downloaded wirelessly or wired. This makes it possible to download the calibration data using different technologies, allowing different conditions to be taken into account (e.g., stationary vehicle, vehicle operation, etc.).

[0025] The radar sensor head according to the invention is characterized in that the radar sensor head can be activated in conjunction with the download of the calibration data. This advantageously ensures that the radar sensor head is used only in an authorized manner, thus largely preventing misuse.

[0026] The radar sensor head according to the invention is characterized in that a sensor ID can be transmitted via the identification unit. This provides a simple method of identifying the radar sensor head, which further protects against access to the radar sensor head.

[0027] A further preferred embodiment of the radar sensor head is characterized in that the sensor ID can be transmitted in encrypted or signed form using the identification unit. This provides a further measure for improved access protection for the radar sensor head.

[0028] A further preferred embodiment of the radar sensor head is characterized in that a public key of an encryption method can be transmitted as the sensor ID. This allows a suitable encryption method to be used to securely identify or authenticate the radar sensor head.

[0029] The radar sensor head according to the invention is characterized in that the calibration data comprises at least one of the following: typical noise level, antenna characteristics, amplitude / phase deviations, position of the antenna elements, temperature characteristics, and temperature response. In this way, different properties of the antennas or the sensor can be advantageously compensated or adjusted during operation of the radar sensor head.

[0030] A further preferred embodiment of the radar sensor head is characterized in that the radar waves received by the at least one receiving antenna can be converted into digital measurement data by an analog-to-digital converter arranged in an evaluation unit of the radar sensor head and can be marked with at least one time information item. In this way, reception sequences can be precisely assigned in time, which supports accurate processing of the measurement data.

[0031] In the following, preferred embodiments of the invention are explained in more detail using highly simplified schematic representations.

[0032] Showing: Fig. 1 is a schematic representation of a proposed radar sensor head; Fig. 2 is a schematic representation of a radar system with an embodiment of a proposed radar sensor head; and Fig. 3 is a schematic representation of a method for manufacturing a radar sensor head, which is not part of the invention.

[0033] In the figures, the same structural elements have the same reference numerals.

[0034] Fig. 1 shows a schematic representation of a proposed radar sensor head 100. The radar sensor head 100 has at least one transmitting antenna 10, which is operable via an associated antenna controller 11. The antenna controller 11 is coupled, among other things, to at least one oscillator or synthesizer 30 for generating a carrier frequency of the radar waves.

[0035] Furthermore, at least one receiving antenna 20 is connected to an associated antenna controller 21. The antenna controller 21 is functionally connected to an evaluation unit 40, wherein received radar waves are converted into digital measurement data by means of an A / D converter arranged in the evaluation unit 40 and are then transformed in a first processing step by means of a preprocessing unit 50. The radar waves received by the receiving antenna 20 of the radar sensor head 100 can be converted into digital measurement data by the analog-to-digital converter of the evaluation unit and can be marked with at least one piece of time information. As a result, the received radar waves or measurement data are converted into a digital format and can thus be processed more easily. Advantageously, the measurement data converted into the digital format can be provided with a time stamp, for exampleeach recorded spectrum can have its own timestamp.

[0036] With the help of the preprocessing unit 50, a fast Fourier transformation (FFT) can preferably be performed. In this way, the sampled values or received radar waves are not transmitted directly after digitization, but rather subjected to a first processing step. The FFT is preferably a range FFT, which can be adapted to the respective application. The range FFT represents a first dimension of the FFT, in which the Doppler effect plays a completely subordinate role and resulting frequency bins are therefore essentially completely distance-dependent.

[0037] Since this transformation requires relatively little memory, the preprocessing unit 50 can be manufactured, for example, using RFCMOS technology and integrated into an MMIC, such as a radio-frequency component of the radar sensor head 100. Since not all range bins are required due to the anti-aliasing filter, for example, 90% or 45% of the bins, the resulting data volume can be reduced, and the FFT can simultaneously be used as a buffer to reduce peak data rates of the radar sensor head 100.

[0038] According to the invention, radar sensor head 100 also includes an identification unit 70, which the radar sensor head 100 uses to authenticate itself to a central control device ("central control unit", not shown). According to the invention, identification unit 70 is configured to initiate a download of calibration data to the central control device upon authentication to the central control device. This advantageously achieves the result that, according to the invention, an authentication step can be simultaneously combined with the download of calibration data suitable for radar sensor head 100, which are used by the central control device during operation. In this way, it is advantageously not necessary to store the calibration data in a memory on radar sensor head 100.

[0039] The result is that the calibration data do not have to be stored in the radar sensor head 100, but rather retrieval of the calibration data can be centralized from the perspective of the central control device. Therefore, only the identification unit is stored in the radar sensor head 100 to authenticate the radar sensor head 100, with the calibration data then being retrieved by the central control device from the cloud, which is designed, for example, as a server of a workshop, the vehicle manufacturer, or the manufacturer of the radar sensor head. The calibration data are preferably stored on the said server in a database. Access to the server via a network or Internet is easily possible. Advantageously, this eliminates the need for memory in the radar sensor head, which makes it more cost-effective. Advantageously, the said calibration data can also be updated from time to time, which, for example,new functionalities for the radar sensor head can be realized.

[0040] By means of the identification unit 70, a sensor ID of the radar sensor head 100 is transmitted during the identification process, e.g., encrypted or signed, to achieve further access protection. It is also conceivable to use a public key of an encryption method used as the sensor ID, thereby providing even better protection against manipulation or misuse.

[0041] According to the invention, the radar sensor head 100 is activated during the download of the calibration data ("component protection"). This ensures that the radar sensor head 100 is only used in an authorized manner, i.e., it prevents manipulation, which is an important criterion, especially for automated vehicles.

[0042] According to the invention, the downloaded calibration data is at least one of the following: typical noise level of the antennas, antenna characteristics, amplitude or phase deviations of the antennas, position of antenna elements, temperature characteristics or responses of the antennas.

[0043] The calibration data can be used, for example, to adjust or compensate for antenna properties that are determined by a technological manufacturing process. The determination of the calibration data or the calibration of the radar sensor head 100 is generally performed once during the manufacturing process, with the calibration data being applied during the operational use of the radar sensor head 100. Using the calibration data, signals can be processed or the antennas of the radar sensor head can be appropriately controlled.

[0044] Deviations of the real antenna pattern from an ideal antenna pattern can be described by so-called "global calibration matrices", which describe deviations caused by phase and amplitude errors, as well as by feedback between channels (see also dissertation M. Schoor, "High-resolution angle estimation for automotive radar systems", 2010).

[0045] By applying calibration via the central control device, costs in the radar sensor head 100 can be advantageously reduced, as less computing power is required there and less power loss occurs at an unfavorable location (e.g., due to the installation location of the radar sensor head 100 in the vehicle). The computing power is advantageously outsourced to the central control device 120. There, the computing power scales significantly better compared to the costs. This enables the execution of calculation algorithms in the central control device that require significantly more computing power than could be available in a single sensor.

[0046] The radar sensor head 100 further comprises a connection 80 to a broadband data line (not shown) via which data is transmitted to the central control device (not shown).

[0047] Fig. 2 shows a basic block diagram of a radar system 200 for a vehicle implemented with the proposed radar sensor head 100. The transformed digital measurement data is transmitted from the radar sensor head 100 to a central control device 120 via a broadband data line 110. The transmitted digital measurement data is assigned a time stamp by the first control unit 60 arranged in the radar sensor head 100 and is also transmitted to the central control device 120. After the signal processing takes place in the central control device 120, the calibration data must be available there, whereby the calibration data is used by a detection unit 150 of the central control device 120.

[0048] The central control device 120 can receive and further process the transmitted digital measurement data, e.g., using a memory 130, a transformation unit 140 for performing a Doppler FFT, the detection unit 150, and a second control unit 160, which functionally interacts with the first control unit 60 of the radar sensor head 100. The time stamps transmitted with the measurement data allow them to be precisely classified in time.

[0049] The central control device 120 has at least one processor for processing received data and at least one memory 130 for at least temporarily storing data. This allows the central control device 120 to at least temporarily store the measurement data transmitted from the radar sensor head 100 via the data line 110 and to process, forward, or output it as required by the respective application. The central control device 120 can be replaced with a more powerful control unit if necessary. Since microprocessors are preferably used in the central control device 120, sophisticated algorithms can be used to process the measurement data, thus achieving more precise calculation results (e.g., angle estimates).

[0050] After downloading, the calibration data is stored in a calibration data memory 170. The downloading occurs via a connection unit 180, which establishes a connection to a server 190, from which the calibration data is downloaded to the calibration data memory 170. The radar system 200 can, for example, be designed as a chirp-sequence radar, but can also be operated with other modulation types. Alternative radar methods can be, for example, slow FMCW radars without a subsequent Doppler FFT, PN (pseudo-noise) radars with an analysis unit as a correlator bank, or an OFDM radar with an analysis unit for performing spectral division. In the radar system 200, the at least one piece of time information can be generated by a first control unit 60 arranged in the radar sensor head 100.The first control unit 60 can, for example, receive and implement control commands transmitted via the data line 110 and provide the digitized measurement data with precise time information. Furthermore, the first control unit 60 can be used to control the radar sensor head 100 and, for example, for monitoring control or cycle control. In order for temporal synchronization to take place in the radar system 200, the first control unit 60 must, for example, assign time stamps for each transmitted chirp or pulse to the transmitted measurement data.

[0051] Cycle so that the central control device 120 can make meaningful use of the measurement data transmitted by the radar sensor head 100.

[0052] The oscillator 30 of the radar sensor head 100 can be adjusted by the second control unit 160 of the central control device 120. By implementing the first control unit 60 in the radar sensor head 100, which functionally interacts with the second control unit 160, the components of the radar sensor head 100 can advantageously be controlled by the central control device 120. Thus, the oscillator(s) of the radar sensor head 100 can also be controlled or regulated directly or indirectly.

[0053] Oscillators of a radar system 200 with at least two radar sensor heads 100 (not shown) can be synchronized with one another by the central control device 120. Several spaced-apart radar sensor heads 100 can be installed in a vehicle and connected to one or more central control devices 120 via data links. When multiple radar sensor heads 100 are used, the control units 60 implemented in the different radar sensor heads 100 allow the respective oscillators of the transmitting antennas 10 to be synchronized with one another. This advantageously increases the accuracy of the measurement results. This allows driver assistance functions or automated driving functions of the vehicle to be optimized. Furthermore, the number of radar sensor heads 100 used can be increased as desired without negatively impacting performance.

[0054] It is also conceivable for several (e.g., three) radar sensor heads 100 to be connected to a central control device 120 (not shown) via corresponding data lines 110. The central control device 120 outputs control commands to the control units 60 of the respective radar sensor heads 100 via the data lines 110, whereby the different radar sensor heads 100, and in particular the respective oscillators 30, are optimally coordinated and synchronized with one another.

[0055] An embodiment of the radar sensor head not shown in the figures provides that it is arranged together with the central control device in a "full sensor", whereby an identification of the full sensor and an associated downloading of calibration data to the full sensor can be realized.

[0056] Fig. 3shows a basic sequence of a method for producing a radar sensor head 100 for a radar system 200, wherein the method is not part of the invention.

[0057] In a step 300, at least one transmitting antenna 10 is provided for generating radar waves.

[0058] In a step 310, at least one receiving antenna 20 for receiving radar waves is provided.

[0059] In a step 320, an interface 80 for connecting the radar sensor head 100 to a data line 110 is provided.

[0060] In a step 330, an identification unit 70 is provided for identifying the radar sensor head, wherein a download of calibration data of the sensor head to a central control device can be initiated by means of the identification unit.

Claims

1. Radar sensor head (100) for a radar system, comprising: - at least one transmitting antenna (10) for generating radar waves and at least one receiving antenna (20) for receiving radar waves; - an interface (80) for connecting the radar sensor head (100) to a data line (110); characterized by - an identification unit (70) for authenticating the radar sensor head with respect to a central control device (120) arranged outside the radar sensor head (100), - wherein a sensor ID is transmitted by means of the identification unit (70), and - wherein the identification unit (70) is configured to initiate a download of calibration data for the sensor head (100) from a server (190) to the central control device (120) when authenticating the radar sensor head (100) with respect to the central control device (120), - and to activate the radar sensor head (100) during the download, - wherein the calibration data are at least one of the following: typical noise level, antenna properties, amplitudes / phase deviations, position of the antenna elements, temperature properties, temperature response.

2. Radar sensor head (100) according to Claim 1, further comprising a preprocessing unit (50) for the defined preprocessing of received data.

3. Radar sensor head (100) according to Claim 1 or 2, characterized in that the calibration data are updated by means of the identification unit (70).

4. Radar sensor head (100) according to one of Claims 1 to 3, characterized in that the identification unit (70) is configured to download the calibration data in a wireless or wired manner.

5. Radar sensor head (100) according to one of the preceding claims, characterized in that the sensor ID is transmitted in encrypted or signed form by means of the identification unit (70).

6. Radar sensor head (100) according to one of the preceding claims, characterized in that a public key of an encryption method is transmitted as the sensor ID.

7. Radar sensor head (100) according to one of the preceding claims, characterized in that the radar waves received by the at least one receiving antenna (20) are converted into digital measurement data by an analogue / digital converter (40) arranged in an evaluation unit (40) of the radar sensor head (100) and are marked with at least one item of time information (Z).

8. Radar system (200) comprising: - at least one radar sensor head (100) according to one of Claims 1 to 7; - the central control device (120) according to Claim 1, formed outside the radar sensor head (100), for sending data and for processing received data, wherein the central control device (120) has a connection unit to the server (190) for downloading calibration data to the central control device (120); and - a data line (110) between the central control device (120) and the at least one radar sensor head (100).

9. Radar system (200) according to Claim 8, wherein the central control device (120) has at least one calibration data memory (130).