Radar system for motor vehicle

Abstract

To provide a radar system for a motor vehicle.SOLUTION: A radar system for a motor vehicle (10) includes a plurality of transmitting / receiving units (12) mounted on various positions in the motor vehicle (10) and an evaluation system for evaluating radar signals received by a plurality of channels in a plurality of processing stages. The radar system supplies a digital time signal representing a radar signal received by a first processing stage for each channel, a last processing stage supplies positioning data on individual radar objects as a result, and at least the last processing stage for the plurality of transmitting / receiving units (12) is implemented in a central evaluation instance (20) communicated by the transmitting / receiving units (12) respectively via raw data interfaces (14). The raw data interfaces (14) respectively have serializers (16) and are configured to perform serial transmission of raw data of the plurality of channels of the transmitting / receiving units (12) to the central evaluation instance (20).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The invention relates to a radar system for a motor vehicle comprising a plurality of transceiver units arranged on separate mounting supports for mounting at various points in the motor vehicle, and an evaluation system for evaluating radar signals received on a plurality of channels in a plurality of processing stages, wherein a first processing stage for each channel provides a digital time signal representative of the received radar signal and a last processing stage provides resulting positioning data of individual radar objects, and wherein at least the last processing stage for the plurality of transceiver units is implemented in a central evaluation instance with which the transceiver units each communicate via a raw data interface. [Background technology]

[0002] Radar systems are used to understand the traffic environment, for example in driver assistance systems for distance control and / or collision warning or avoidance, as well as in systems for autonomous driving. Due to constantly increasing performance requirements for radar sensors, especially with regard to angular resolution, radar sensors with larger antenna diameters are increasingly being used.

[0003] WO 2018 / 137809 A1 describes a radar system for a motor vehicle that has multiple synchronized transceiver units, which provide an overall large number of available receiving channels, and enables high-resolution angle measurements by matching the amplitude and phase of radar echoes received by multiple offset antennas, where the multiple transceiver units can be installed relatively far apart within the motor vehicle.

[0004] The transmit / receive unit typically operates according to the FMCW (Frequency Modulated Continuous Wave) principle. The frequency of the transmitted radar signal is modulated in a ramp pattern. A series of frequency ramps is transmitted within each measurement period. The radar echoes received by each receive channel are mixed with the components of the transmitted signal at the time of reception, resulting in a lower-frequency beat signal. Due to the distance dependence of the signal propagation time and the Doppler effect, the beat frequency depends on both the object distance and the relative velocity of the object. Various methods are known for separating the distance-dependent and velocity-dependent components from each other. Furthermore, the time signal recorded over the measurement period is typically converted by a one-dimensional or multidimensional Fourier transform into a frequency spectrum in which each located object is represented by a peak at a specific frequency.

[0005] When using multiple sensors at various mounting locations in a vehicle, the sensor signals (positioning data) have typically been fused together after they have already been fully processed. Modern vehicle designs, for example for autonomous vehicles (SAE Class 4 and 5), require a significant increase in sensor performance. This can be achieved, for example, by radar systems of the type mentioned at the outset, as described in DE 10 2018 200391 A1. In such systems, multiple sensors distributed at different locations on the vehicle work in concert, thereby providing additional information (e.g., sensor A transmits from position X, and sensor B receives an echo at position Y). In such an operating mode, it may be necessary to first fuse the unprocessed signals ("raw data") of the individual sensors and then evaluate them together.

[0006] In vehicles, the installation space for sensors is often severely limited, and there are very strict requirements on the volume and power consumption of the box. These requirements can be more easily met by a modular design of the radar system, in which multiple independent radar sensor heads are operated, with no or significantly reduced signal processing, and in which the evaluation of the radar signals is performed in a central control unit.

[0007] This reduces the total number of ECUs in the vehicle, thereby achieving cost savings and synergies, and more flexible partitioning options for vehicle manufacturers. It also enables mixed operation of radar with video, lidar, and other sensor modalities, as well as data fusion at the raw data level, performance improvements through software updates at the ECU level without replacing the sensor head, easier integration in difficult locations within the vehicle (by reducing box volume), and easier heat dissipation in critical locations (by reducing power losses in the radar head by offloading the processor and ECU to a central or collective control unit).

[0008] Furthermore, the increasing complexity of vehicles has led to a significant increase in the variety of sensor configurations. Due to the large number of sensors per vehicle, the sheer number of combination possibilities and sensor variations makes simple classification and optimization of the various sensor types increasingly difficult. Against this background, a modular platform concept, where specialized sensor types can be derived from a common, general-purpose platform, seems desirable.

[0009] Development costs can also be reduced through appropriate platform concepts and by using as many common parts as possible in terms of hardware and software. Separating the radar sensor head and evaluation unit makes it possible to reuse existing components and "upgrade" individual modules individually (e.g., just the radar head or just the central unit). It also makes it possible to operate a large number of different sensor heads suited to each application without having to adapt the backend to them.

[0010] However, to achieve high angular resolution in individual radar heads (transmitter / receiver units), each radar head requires a large number of parallel receive channels, and in this case a correspondingly large number of transmit channels for transmitting raw data to a central evaluation instance. This makes wiring the various system components within the vehicle difficult. With a large number of sensor heads in an individual vehicle, the total cable length can be on the order of 15 meters or more. Therefore, using multi-core cables increases the space required for the cable harness and often makes cable installation difficult. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] WO2018 / 137809A1 [Patent Document 2] DE102018200391A1 Summary of the Invention [Problem to be solved by the invention]

[0012] The object of the invention is to facilitate the installation of a radar system of the type mentioned at the outset on a vehicle. [Means for solving the problem]

[0013] According to the invention, this problem is solved in that the raw data interfaces each have a serializer, which is configured to serially transmit the raw data of the channels of the transceiver unit to a central evaluation instance.

[0014] Serializing the raw data transmitted from the individual transceiver units to the evaluation instance allows a factor-of-10 reduction in the number of wires required in the cables connecting the various components, thereby saving material and space and increasing the flexibility of the cables, which can better overcome difficult installation situations.

[0015] Advantageous embodiments of the invention are set forth in the dependent claims. The serializer may be a separate component on the circuit board of the transceiver unit, or alternatively, the serializer may be integrated at chip level into the radar MMIC or the processor of the transceiver unit.

[0016] Physical serializers / deserializers are known, which use specialized hardware to convert parallel data streams, such as time signals generated by various receiving channels, into serial data streams that transmit the time signals sequentially to the evaluation instance, thereby making it possible to transmit multiple channels using only one core in the transmission cable. Various interface standards may be used for serial data transmission, allowing high transmission rates of the order of 15 Gbit / s and above. The transmission cable may be, for example, a coaxial cable or a twisted pair. In one embodiment, transmission may also take place via a fiber optic cable, which allows particularly high data rates.

[0017] On the side of the processing instance, a corresponding deserializer may be provided which converts the serial signal back into a parallel signal for multiple channels, so that further evaluation can again be carried out in parallel on the various channels.

[0018] The serially transmitted data may be digitized unprocessed radar signals (time signals) or digitally pre-processed raw data. Typical preprocessing in this context is filtering, selection and compression.

[0019] Generally, control and control information, and possibly also synchronization signals or data for sender modulation, must be transmitted from the evaluation instance (back end) to the transmitting / receiving unit (front end). However, since the required data rates are significantly lower in this transmission path, it is conceivable to use a different bus system and / or transmission protocol for the opposite transmission direction.

[0020] The various transmitting and receiving units may be synchronized with one another, which allows for a consistent data evaluation, which allows for a large antenna aperture and thus a high angular resolution.

[0021] However, non-coordinated operation of the transmitting and receiving units is also possible, as is joint evaluation of radar data of the transmitting and receiving units together with data of other sensor systems such as video, lidar, etc. in the same central evaluation instance.

[0022] To achieve time synchronization of multiple transmitting / receiving units with each other and / or with evaluation instances, distributed clocks can be used, which are adjusted via the data interface. To adjust the clocks, timestamps can be transmitted sporadically via the data interface, for example. Alternatively, individual pulses can be sent at specific pre-set times. The clocks should be able to readjust the frequency deviation of their internal clock generators depending on the received timestamps.

[0023] The central evaluation instance may be implemented on one of the mounting supports, but may also be implemented on a control device separate from the mounting supports. A way to further reduce cable length is to group multiple sensors in spatially close control devices ("zone control devices") before bundling them and transferring them to a central unit.

[0024] The embodiments will be described in detail below with reference to the drawings. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a plan view of a vehicle equipped with a radar system according to the invention; [Figure 2] Block diagram of the radar system according to Figure 1. DETAILED DESCRIPTION OF THE INVENTION

[0026] 1 shows a schematic representation of a radar system for a vehicle 10. The radar system includes a number of (ten in the illustrated example) transmitting / receiving units 12, which are mounted separately from one another at various locations within the vehicle, each on its own mounting support (board or housing).

[0027] Each transceiver unit 12 has as a signal output a raw data interface 14 which is connected via a physical serializer 16 and a cable 18 to a central evaluation instance 20 which evaluates the raw data of all transceiver units 12.

[0028] 2, the central evaluation instance 20 and two of the transceiver units 12 are shown as separate blocks. Substantially all functionality of the individual transceiver units 12 is implemented in one or more semiconductor modules 22, for example a Monolithic Microwave Integrated Circuit (MMIC) or a System on Chip (SoC). The antenna array of the transceiver unit 12 is shown only symbolically in the drawing and in the illustrated example comprises individual transmit and receive antennas Tx and Rx that are horizontally offset from one another so as to achieve angular resolution in azimuth.

[0029] By way of example, the radar system shown here can be assumed to operate according to the FMCW principle. The transmitting antenna of each transceiver unit 12 transmits a series of ramp-like, frequency-modulated radar signals for each measurement period. The signals reflected from the positioned object are received by the receiving antenna and mixed with the transmitted signal components at the time of reception, resulting in a low-frequency beat signal for each antenna element. From the frequency and phase, distance and relative velocity information about the positioned object are obtained. These beat signals are evaluated for each receiving antenna in separate receive channels of the semiconductor module 22. Here, the complex amplitude of the beat signal is sampled over the measurement period using a high-speed clock and digitized. The digitized data forms raw data, which is transmitted to the central evaluation instance 20 via the raw data interface 14.

[0030] In the illustrated example, the central evaluation instance 20 is formed by a control device, which also controls the functions of the transceiver units. In the control device, the time signals of all transceiver units 12 are jointly evaluated in a high-speed processor 24 with an associated working memory 26. During the evaluation, the time signals of each receiving channel are converted by a fast Fourier transform into a spectrum in which each located object is indicated by a peak at a specific frequency. By matching the data acquired with the various frequency ramps, distance information is separated from relative velocity information in a known manner, so that the distance and relative velocity of each located object can be determined. Furthermore, by comparing the amplitude and phase of the signals received on the various receiving channels, the azimuth angle of each located object is determined. The information thus acquired about the located objects is output via a vehicle interface 28, such as a high-speed Ethernet interface or a CAN bus, to other electronic components in the vehicle, such as driver assistance systems. A memory 30 (e.g., a flash memory or a hard disk) enables the storage or at least temporary storage of the evaluation results in the central evaluation instance 20.

[0031] In the illustrated example, each transceiver unit 12 comprises multiple semiconductor modules 22, each having its own raw data interface 14 with an associated serializer 16. By way of example, it can be assumed that each semiconductor module 22 pre-evaluates and digitizes received signals from 40 receive antennas Rx in parallel receive channels.

[0032] In the serializer 16, the time signals arriving in parallel on the 40 channels are serialized and transmitted as a serial signal in series on only one core of the cable 18 to the central evaluation instance 20. The cable 18 therefore only needs to have one core for each semiconductor module 22, rather than 40.

[0033] The central evaluation instance 20 has a deserializer 32 for each transceiver unit 12 by which the received signals are deserialized before being forwarded in parallel to the processor 24 .

[0034] In the illustrated example, in addition to the radar system's transceiver unit 12, a video camera V is also provided, the data of which is likewise transmitted to the processor 24 for further processing.

[0035] For control and synchronization functions, the central evaluation unit 20 includes a control unit 34 which receives a time signal from a local real-time clock 36 . Each transceiver unit 12 also includes a control unit 38 that receives a time signal from a local real-time clock 40 and drives and controls the semiconductor module 22 .

[0036] The control unit 34 of the evaluation instance 20 and the control unit 38 of each transceiver unit 12 communicate with each other via one or more cores of the cable 18 connecting these components. In the example shown, each control unit is associated with a serializer / deserializer 42, which serializes the transmitted signals and deserializes the received signals, respectively. However, since the data exchange between the control units 34, 38 is much smaller in scope than the raw data transmission of the semiconductor module 22, other communication paths and protocols may also be provided for the control unit communication.

[0037] The local real time clocks 36, 40 are coordinated with each other by occasionally exchanging reference signals so that the transceiver units 12 are selectively synchronized with each other and their data can be coherently evaluated.

[0038] Thus, signals transmitted by one of the transmitting and receiving units and received by the other can also be evaluated in the processor 24. The two antenna arrays then form a full array with a very large aperture due to the large distance between the transmitting and receiving units, which allows high resolution angular measurements. [Explanation of symbols]

[0039] 10 Radar System 12 Transmitting and receiving unit 14 Raw Data Interface 16 Serializers 18 Cable 20 central evaluation instances 22 Semiconductor Module 24 processors 26 Working Memory 28 Vehicle Interface 30 memory 32 Deserializer 34 Control Unit 36 Local Real Time Clock 38 Control Unit 40 Local Real Time Clock 42 Serializer / Deserializer V Video Camera Tx Transmitting Antenna Rx receiving antenna

Claims

1. A radar system for a motor vehicle (10), comprising: a plurality of transceiver units (12) arranged on separate mounting supports for attachment at various locations within the motor vehicle (10); and an evaluation system for evaluating radar signals received on a plurality of channels in a plurality of processing stages, wherein a first processing stage for each channel supplies a digital time signal representing the received radar signal, a last processing stage supplies positioning data of individual radar objects as a result, and at least said last processing stage for said plurality of transceiver units (12) is implemented in a central evaluation instance (20) with which the transceiver units (12) communicate via raw data interfaces (14) respectively. The radar system according to claim 1, wherein each of said raw data interfaces (14) has a serializer (16), and the serializer (16) is configured to serially transmit the raw data of the plurality of channels of the transceiver unit (12) to the central evaluation instance (20).

2. The radar system according to claim 1, wherein at least one of said transceiver units (12) has a plurality of semiconductor modules (22) each evaluating signals from a defined number of receiving antennas (Rx), and a unique serializer (16) is provided for each of said semiconductor modules (22).

3. The radar system according to claim 1, wherein the central evaluation instance (20) for each of said serializers (16) within the transceiver unit (12) has a deserializer (32) for converting the serial received signal back into a parallel signal sequence for further processing by a processor (24).

4. The radar system according to claim 1, wherein the central evaluation instance (20) and the transceiver unit (12) each have a first control unit (34) and a second control unit (38) for controlling the functions of the radar system, and the second control unit (38) of the transceiver unit (12) is connected to the first control unit (34) of the central evaluation instance (20) via a communication path.

5. The radar system according to claim 4, wherein the communication path for the first control unit (34) and the second control unit (38) is separate from the communication path for the raw data.

6. The second control unit (38) of the transceiver unit (12) is synchronized with each other and with the first control unit (34) of the central evaluation instance (20), and the central evaluation instance (20) is configured for a coherent evaluation of the signals of the transceiver unit (12). The radar system according to claim 4 or 5.

7. The radar system according to claim 6, wherein the central evaluation instance (20) and each transceiver unit (12) have local real-time clocks (36, 40) for synchronization of the first control unit (34) and the second control unit (38).

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