radar equipment

Abstract

To provide a radar device capable of effectively utilizing a plurality of antennas.SOLUTION: A radar device comprises: a transmission antenna system; a reception antenna system; and a control unit for outputting a transmission signal to the transmission antenna system and for acquiring a reception signal from the reception antenna system. At least one of the transmission antenna system and the reception antenna system includes an antenna set with different gain peak frequencies. The control unit switches between a high frequency mode, a low frequency mode, and a medium frequency mode. In the high frequency mode, a transmission signal of a center frequency corresponding to an antenna with a high peak frequency out of the antenna set is generated. In the low frequency mode, a transmission signal of a center frequency corresponding to an antenna with a low peak frequency is generated. In the medium frequency mode, a transmission signal of a center frequency included in a frequency range from a center frequency in the high frequency mode to a center frequency in the low frequency mode is generated.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a radar device.

Background Art

[0002] In Patent Document 1, for each of the transmitted signals due to the used modulation, the antenna array of the transmitting antenna and / or the antenna array of the receiving antenna is operated in different switching states. For example, a signal having an increasing frequency is received by the antenna array in the first switching state, and a signal having a decreasing frequency modulation is received by the antenna array having the second switching state. In this case, for the transmission of the transmitted signal in two modulations, the antenna array of the transmitting antenna is operated in the same switching state. Alternatively, various switching states for the transmitting antenna are also possible for various modulations of the transmitted signal.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, a signal is transmitted for each antenna array. However, in the technology of Patent Document 1, there is room for improvement in the effective utilization of a plurality of antennas.

[0005] An object of the present disclosure is to provide a radar device capable of effectively utilizing a plurality of antennas.

Means for Solving the Problems

[0006] The following describes the technical means of solving the problem described in this disclosure. Note that the claims and the reference numerals in parentheses in this section indicate the correspondence with the specific means described in the embodiments detailed later, and do not limit the technical scope of this disclosure.

[0007] A first aspect of this disclosure is a transmitting antenna system (2) including an antenna that transmits a transmission signal, A receiving antenna system (3) includes an antenna that receives the transmitted signal reflected from the outside as a received signal, A control unit (5) that outputs a transmission signal to the transmitting antenna system and acquires a reception signal from the receiving antenna system, Equipped with, At least one of the transmitting antenna system and the receiving antenna system includes a set of antennas with different peak gain frequencies. The control unit is The system switches between three modes: a high-frequency mode that generates a transmission signal with a center frequency corresponding to the antenna with the highest peak frequency among the antenna set; a low-frequency mode that generates a transmission signal with a center frequency corresponding to the antenna with the lowest peak frequency; and a medium-frequency mode that generates a transmission signal with a center frequency within the frequency range from the center frequency in the high-frequency mode to the center frequency in the low-frequency mode. 、 The receiving antenna system is, It includes four sets of antennas. Each antenna set consists of an antenna with a relatively high peak frequency and an antenna with a relatively low peak frequency. In multiple sets, antennas with relatively high peak frequencies are spaced equally apart, and antennas with relatively low peak frequencies are also spaced equally apart. The spacing between antennas with relatively high peak frequencies and the spacing between antennas with relatively low peak frequencies differs from that of each other. Furthermore, the antennas with relatively high peak frequencies and the antennas with relatively low peak frequencies are arranged symmetrically in the direction of antenna arrangement, and the center of the arrangement of four antennas with relatively high peak frequencies coincides with the center of the arrangement of four antennas with relatively low peak frequencies. It is a radar device.

[0008] According to this embodiment, in addition to the high-frequency and low-frequency modes corresponding to each antenna, transmission and reception in a medium-frequency mode becomes possible. As a result, signal transmission and reception by an antenna formed by combining the antennas constituting the set becomes possible, in addition to the transmission and reception of signals corresponding to each individual antenna constituting the set. Therefore, multiple antennas can be effectively utilized. [Brief explanation of the drawing]

[0009] [Figure 1] This is a diagram showing the overall configuration of the first embodiment. [Figure 2] This is a schematic diagram showing an example of the configuration of an antenna. [Figure 3] This is a schematic diagram showing an example of the configuration of an antenna pair. [Figure 4] This is a schematic diagram for showing the functional configuration of the MMIC. [Figure 5] This is a graph for explaining the characteristics of the antenna and the filter circuit. [Figure 6] This is a schematic diagram for explaining the antenna position. [Figure 7] This is a schematic diagram for explaining the antenna arrangement pattern. [Figure 8] This is a schematic diagram for explaining the phase difference due to the change in the angle of arrival. [Figure 9] This is a flowchart for explaining the control flow. [Figure 10] This is a schematic diagram showing an example of the configuration of the antenna pair in the second embodiment <000\079> [Figure 11] This is a schematic diagram for explaining the antenna position. [Figure 12] This is a graph for explaining the directivity characteristics of the antenna.

Embodiments for Carrying Out the Invention

[0010] Hereinafter, a plurality of embodiments of the present disclosure will be described based on the drawings. In each embodiment, the same reference numerals may be assigned to corresponding components, and redundant explanations may be omitted. Further, when only a part of the configuration is described in each embodiment, the configuration of other embodiments described previously can be applied to other parts of the configuration. Furthermore, not only the combinations of configurations explicitly shown in the description of each embodiment, but also the configurations of a plurality of embodiments can be partially combined with each other as long as there is no problem with the combination.

[0011] (First Embodiment) Regarding the first embodiment of the present disclosure, it will be described with reference to FIGS. 1 to 9. The radar system 1 is mounted on a moving body such as a vehicle. The radar system 1 transmits a transmission signal, receives the transmission signal reflected by an object as a reception signal, and detects the distance to a target, which is an object that reflects the transmission signal, the relative speed with the target, the azimuth of the target, etc. as target information.

[0012] The target information output from the radar system 1 is input to an in-vehicle ECU (Electronic Control Unit) via an in-vehicle network such as CAN (Control Area Network (registered trademark)) and Ethernet (registered trademark). The in-vehicle ECU executes various processes for automatic driving and advanced driving assistance of the vehicle based on the target information of each acquired target.

[0013] Examples of the processes based on the target information include a collision avoidance process, a warning process, etc. The collision avoidance process is a process for performing vehicle control to avoid a collision with a target by controlling a braking system, a steering system, etc. based on the target information of each target. The warning process is a process for warning a driver of the possibility of a collision with a target based on the target information of each target.

[0014] The radar device 1 of the present embodiment includes a transmission antenna system 2, a reception antenna system 3, a MMIC 5, and a controller 6. The transmission antenna system 2 includes at least one transmission antenna 4 as an antenna for transmitting a transmission signal. The transmission antenna 4 converts an electrical signal as a transmission signal supplied from the MMIC 5 into a radio wave signal and transmits it to the outside world. The transmission antenna 4 is configured to include at least one antenna element. For example, as shown in FIG. 2, the transmission antenna 4 is a patch antenna including a plurality of antenna elements 40 having a flat plate shape. The antenna element is arranged on the surface opposite to the ground plane on a dielectric substrate provided with the ground plane on one surface so as to face the ground plane. The plurality of antenna elements 40 are arranged in a state of being arranged in a predetermined arrangement direction. The plurality of antenna elements 40 are connected in series, for example, by a feed line 41 for supplying an electrical signal.

[0015] The transmitting antenna 4 described above is designed in terms of the shape, size, number, and arrangement of its antenna elements so that it has a wider frequency band than the receiving antennas 4a and 4b in the receiving antenna system 3 described later. For example, this antenna is designed to have a frequency band of 76 GHz to 81 GHz. One transmitting antenna 4 is connected to each transmitting channel of the MMIC 5. Since the total number of transmitting channels of the MMIC in this embodiment is 1, the total number of antennas that transmit the signal is also 1.

[0016] As shown in Figure 3, the receiving antenna system 3 includes receiving antennas 4a and 4b and a filter circuit 42, which receive radio wave signals, including the transmitted signal reflected from the outside, as received signals. The receiving antennas 4a and 4b convert the received signal, which is a radio wave signal, into an electrical signal and output it to the MMIC 5. Similar to the transmitting antenna 4, the receiving antennas 4a and 4b are patch antennas in which at least one or more antenna elements 40 are connected in series by a feed line 41.

[0017] In the receiving antenna system 3, the receiving antennas 4a and 4b are arranged so that two are connected to each receiving channel in the MMIC. Since the total number of receiving channels in the MMIC in this embodiment is 4, the total number of receiving antennas is 8. Hereinafter, the sets of receiving antennas 4a and 4b connected to each receiving channel will be referred to as antenna sets RX1, RX2, RX3, and RX4.

[0018] In each antenna set RX1, RX2, RX3, and RX4, the receiving antennas 4a and 4b are arranged adjacent to each other. The receiving antennas 4a and 4b are arranged so that the direction of the antenna elements is parallel. Furthermore, each receiving antenna 4a and 4b in a single antenna set RX1, RX2, RX3, and RX4 is designed to have different antenna gain frequency characteristics. Specifically, each antenna set RX1, RX2, RX3, and RX4 has a receiving antenna 4a with a relatively high peak frequency of antenna gain and a receiving antenna 4b with a relatively low peak frequency of antenna gain.

[0019] For example, the high-frequency receiving antenna 4a has a peak frequency of 80.5 GHz, and the low-frequency antenna 4b has a peak frequency of 76.5 GHz. Each receiving antenna 4a and 4b is designed to operate within the frequency band of the transmitting antenna 4 in the transmitting antenna system 2. In other words, each receiving antenna 4a and 4b is designed to have a narrower bandwidth than the transmitting antenna 4. Alternatively, it can be said that a pair of antennas 4a and 4b are designed to have a narrower bandwidth than the non-paired antenna 4. That is, in the radar device 1 of this embodiment, the receiving antenna system 3 of the transmitting antenna system 2 and the receiving antenna system 3 includes a pair of antennas with different frequency characteristics.

[0020] The filter circuit 42 is an electrical circuit that suppresses the passage of signals in a specific frequency band. A filter circuit 42 is provided for each receiving antenna 4a and 4b in the receiving antenna system 3. The filter circuit 42 is designed so that each receiving antenna 4a and 4b has a pass-through characteristic that suppresses signals in a frequency band that includes the peak frequency of the other receiving antenna 4a or 4b. For example, in the example shown in Figure 5, the filter circuit connected to receiving antenna 4a has a pass-through characteristic that suppresses the frequency band centered around 76.5 GHz. The filter circuit connected to receiving antenna 4b has a pass-through characteristic that suppresses the frequency band centered around 80.5 GHz.

[0021] For the receiving antennas 4a and 4b described above, the antenna positions shown in Figure 6 are defined. The antenna position is defined as the center of the shape of the receiving antennas 4a and 4b as a group of antenna elements 40. Furthermore, for signals at frequencies where the antenna gains shown in Figure 6 match, the receiving antennas 4a and 4b function as a combined antenna 4c consisting of two rows of antenna elements 40. In this case, the antenna position is defined as the center of the shape of the combined antenna 4c as a group of antenna elements 40 from each receiving antenna 4a and 4b. In this embodiment, as shown in Figure 6, the center of the antenna positions of each receiving antenna 4a and 4b becomes the antenna position of the combined antenna 4c.

[0022] The receiving antennas 4a and 4b described above are arranged in a predetermined direction with a specified interval between them. The arrangement pattern of receiving antennas 4a and 4b in the entire receiving antenna system 3 will now be explained. As shown in Figure 7, antenna sets RX1, RX2, RX3, and RX4 are arranged in order from left to right on the page. Here, let d be the minimum distance between receiving antennas 4a and 4b.

[0023] In antenna set RX1, the receiving antenna 4b is positioned on the outside, and the distance between it and the inner, high-frequency antenna 4a is 3d. Adjacent to the receiving antenna 4a in antenna set RX1, the receiving antenna 4b in antenna set RX2 is positioned with a distance d. The receiving antenna 4a in antenna set RX2 is positioned with a distance d relative to the receiving antenna 4b. The receiving antenna 4a in antenna set RX3 is positioned with a distance 2d relative to the receiving antenna 4b in antenna set RX2. Furthermore, the arrangement of the receiving antennas 4a and 4b in antenna sets RX3 and RX4 is a left-right inversion of that in antenna sets RX1 and RX2. As described above, in the receiving antenna system 3, the distance between antennas with high peak frequencies and the distance between antennas with low peak frequencies in the multiple receiving antennas 4a and 4b pairs are arranged differently.

[0024] The MMIC5 is constructed by integrating its various components onto a single semiconductor chip made of silicon or the like. As shown in Figure 4, the MMIC5 includes a control unit 50, a transmission signal generation unit 51, and a receiver 52.

[0025] The control unit 50 is a digital circuit and, based on a control signal from the controller 6, causes the transmission signal generation unit 51 to generate a transmission signal. For example, the control unit 50 generates a transmission signal based on a digital signal that has a predetermined center frequency and whose frequency changes according to time.

[0026] The transmission signal generation unit 51 receives an instruction signal from the control unit 50 and generates a millimeter-wave transmission signal corresponding to the instruction signal. The transmission signal generation unit 51 is composed of, for example, a D / A converter and a voltage-controlled oscillator. For example, when the transmission signal generation unit 51 receives a digital signal whose frequency changes with time, which is output as an instruction signal, it converts it into an analog signal using a D / A converter. Then, the transmission signal generation unit 51 generates a high-frequency signal in the millimeter-wave band from the analog signal using a voltage-controlled oscillator and outputs it as a transmission signal to the transmission antenna system 2. The transmission signal generation unit 51 also distributes a portion of the output transmission signal from the original signal at a predetermined ratio and outputs it to the receiver 52. In the following, the signal output to the receiver 52 will be referred to as the local signal.

[0027] The receiver 52 includes a signal mixing unit 54 and an A / D converter 55. A receiver 52 is provided for each receiving channel. The signal mixing unit 54 generates a beat signal by mixing the local signal from the transmission signal generation unit 51 and the received signal Sr from the receiving antenna, and outputs it to the A / D converter 55. The generated beat signal is an interference signal representing the frequency difference between the received signal and the local signal. The beat signal is output to the A / D converter 55 after high-frequency components that deviate from the frequency difference between the received signal and the local signal are filtered out by a low-pass filter (not shown).

[0028] The A / D converter 55 samples the beat signal at predetermined time intervals and converts it into digitized beat signal data. This beat signal data is output to the controller 6 as reception result data related to the received signal.

[0029] The MMIC5 switches and controls the center frequency of the transmission signal output by the control unit 50. Specifically, the MMIC5 can execute a high-frequency mode that generates a transmission signal with a center frequency corresponding to the higher-frequency receiving antenna 4a of the receiving antenna pair 4a and 4b. The MMIC5 can also execute a low-frequency mode that generates a transmission signal with a center frequency corresponding to the lower-frequency receiving antenna 4b. Furthermore, the MMIC5 can execute a medium-frequency mode that generates a transmission signal with an intermediate center frequency that falls within the range between the center frequencies of the high-frequency mode and the low-frequency mode. The MMIC5 switches and controls these three modes.

[0030] Here, the intermediate center frequency in the medium frequency mode is defined as the frequency at which the antenna gains of each receiving antenna 4a and 4b are substantially equal. For example, in this embodiment, as shown in Figure 5, the intermediate center frequency is 78.5 GHz.

[0031] In high-frequency mode, in the receiving antenna system 3, the received signal mainly received by the receiving antenna 4a is output to the MMIC 5. In the receiving antenna 4b, due to the frequency characteristics of the antenna gain and the passthrough characteristics of the filter circuit 42, the received signal output to the MMIC 5 in high-frequency mode is effectively cut off.

[0032] Therefore, in the high-frequency mode, it can be considered to be essentially equivalent to having only the receiving antenna 4a. In other words, in this mode, as shown in Figure 7, it can be considered that the received signal is being received by four receiving antennas 4a arranged at intervals of 2d from each other.

[0033] On the other hand, in low-frequency mode, the received signal mainly received by receiving antenna 4b is output to MMIC 5, and the received signal received by receiving antenna 4a is effectively cut off. In other words, in this mode, as shown in Figure 7, the received signal can be considered to be received by four receiving antennas 4a arranged at intervals of 4d from each other.

[0034] Furthermore, in the medium frequency mode, the received signal is received by both receiving antennas 4a and 4b of each antenna set and output to the MMIC 5. As a result, the receiving antennas 4a and 4b function as a single combined antenna 4c. In particular, in this embodiment, the intermediate center frequency is set to a frequency at which the antenna gain and filter pass characteristics substantially match, so that a received signal that has passed through antennas and filter circuits with substantially identical gain and pass characteristics is obtained.

[0035] As described above, the entire pair of receiving antennas 4a and 4b can be considered as a single combined antenna 4c. Therefore, in this mode, as shown in Figure 7, the received signal can be considered to be received by four receiving antennas 4c arranged at intervals of 3d from each other.

[0036] As described above, by switching the center frequency of the transmitted signal, it becomes possible to substantially change and control the arrangement pattern of the receiving antennas. In other words, by switching the frequency, it becomes possible to virtually change and control the spacing between antennas.

[0037] By controlling the spacing of the receiving antennas as described above, the field of view and angle measurement accuracy of the radar device 1 can be switched. That is, as shown in Figure 8, the arrival angle θ at each receiving antenna can be estimated by obtaining the phase difference dsinθ of the received signals from each antenna arranged at interval d. However, if the phase difference dsinθ exceeds half a wavelength of the received signal, accurate angle estimation becomes impossible due to angle folding. In other words, the range of spacing d in which angle folding does not occur is less than half a wavelength.

[0038] On the other hand, the larger the interval d, the better the sensitivity to phase difference detection, allowing for the detection of small phase differences, thus improving the accuracy of arrival angle detection. In other words, the smaller the interval d, the larger the field of view, and the lower the accuracy of arrival angle estimation. Conversely, the larger the interval d, the smaller the field of view, and the higher the accuracy of arrival angle estimation.

[0039] Therefore, the field of view and arrival angle estimation accuracy can be switched by virtually changing the arrangement pattern in accordance with the switching control of the center frequency. In particular, in this embodiment, the spacing becomes larger in the low frequency mode, enabling detection with a wide field of view. In the high frequency mode, the spacing becomes smaller, enabling highly accurate arrival angle detection. In the medium frequency mode, the spacing is intermediate between the low frequency mode and the high frequency mode, resulting in intermediate performance in field of view and accuracy.

[0040] Controller 6 is a control device that outputs switching commands for each of the modes described above to the MMIC. Controller 6 is configured to include at least one dedicated computer. The dedicated computer that makes up Controller 6 may be a sensing ECU (Electronic Control Unit) specialized in controlling the MMIC 5. The dedicated computer that makes up Controller 6 may be a sensor integration ECU that comprehensively controls multiple types of sensors mounted on the vehicle. The dedicated computer that makes up Controller 6 may be an integration ECU that integrates the driving control of the vehicle. The dedicated computer that makes up Controller 6 may be a decision ECU that determines driving tasks in the driving control of the vehicle. The dedicated computer that makes up Controller 6 may be a monitoring ECU that monitors the driving control of the vehicle. The dedicated computer that makes up Controller 6 may be an evaluation ECU that evaluates the driving control of the vehicle.

[0041] The dedicated computer constituting the controller 6 may be a navigation ECU that navigates the vehicle's driving path. The dedicated computer constituting the controller 6 may be a locator ECU that estimates the vehicle's own state variables. The dedicated computer constituting the controller 6 may be an actuator ECU that controls the vehicle's driving actuators. The dedicated computer constituting the control unit may be an HCU (HMI (Human Machine Interface) Control Unit) that controls the presentation of information in the vehicle. The dedicated computer constituting the controller 6 may be a computer other than the vehicle that, for example, constructs an external center or mobile terminal that can communicate with the vehicle.

[0042] The dedicated computer comprising the controller 6 has at least one memory 6a and one processor 6b. The memory 3a is at least one type of non-transitory tangible storage medium, such as semiconductor memory, magnetic media, and optical media, which non-temporarily stores programs and data that can be read by the computer. Here, storage may be accumulation where data is retained even when the sensor system is turned off, or temporary storage where data is erased when the sensor system is turned off. The processor 6b includes at least one type as a core, such as a CPU (Central Processing Unit), GPU (Graphics Processing Unit), RISC (Reduced Instruction Set Computer)-CPU, DFP (Data Flow Processor), and GSP (Graph Streaming Processor).

[0043] In the controller 6, the processor 6b executes multiple instructions contained in the control program stored in memory 3a to control the transmit / receive unit 20. This allows the controller 6 to construct a functional block for controlling the transmit / receive unit 20.

[0044] With these functional blocks, the radar control method in which the controller 6 controls the radar device 1 is executed according to the control flow shown in Figure 9. This control flow is executed repeatedly while the vehicle is starting up. In this control flow, each "S" represents multiple steps executed by multiple instructions included in the control program.

[0045] First, in S10, the controller 6 performs radar operation in the currently set mode, that is, generating a transmit signal at the center frequency corresponding to the mode and processing the reception of the receive signal. In the following S20, it determines whether or not it is time to switch modes. Specifically, it determines whether or not the radar operation in the current mode has been performed for a specified time or a specified number of frames. In this case, the three modes will switch over in a specified order over time.

[0046] Alternatively, the controller 6 may determine the switching timing according to the driving scene based on the type of driving area the vehicle is in. For example, the controller 6 may determine that it is time to switch to high-frequency mode when the vehicle enters a highway from an ordinary road. Furthermore, the controller 6 may determine that it is time to switch to medium-frequency mode when the vehicle is driving on an ordinary road. In addition, the controller 6 may determine that it is time to switch to low-frequency mode when the vehicle enters an intersection or parking lot.

[0047] Alternatively, the controller 6 may determine the switching timing according to the driving scene based on the operation of a specific function in the vehicle. For example, the controller 6 may determine that it is time to switch to high-frequency mode when ACC (Adaptive Cruise Control) starts operating. The controller 6 may also determine that it is time to switch to low-frequency mode when AEB (Autonomous Emergency Braking) starts operating. Furthermore, the controller 6 may determine that it is time to switch to medium-frequency mode when all of the functions have finished operating. The controller 6 may also appropriately switch between mode switching control based on time and mode switching control based on driving scene.

[0048] If it is determined that it is not time to switch modes, this flow returns to S10. On the other hand, if it is determined that it is time to switch modes, this flow proceeds to S30. In S30, the mode switch is performed.

[0049] According to the first embodiment described above, in addition to the high-frequency and low-frequency modes corresponding to each antenna, transmission and reception in a medium-frequency mode becomes possible. This makes it possible to transmit and receive signals using an antenna formed by combining the antennas that make up the set, in addition to transmitting and receiving signals corresponding to each individual antenna in the set. Therefore, multiple antennas can be effectively utilized. In particular, in this embodiment, since there is no need to use additional channels and antennas to support multiple modes, costs can be reduced.

[0050] (Second embodiment) As shown in Figures 10 and 11, the second embodiment is a modification of the first embodiment.

[0051] In the second embodiment, the high-frequency receiving antenna 4a and the low-frequency receiving antenna 4b in the antenna set have different shapes. Specifically, one of the antennas (for example, the low-frequency side) has a shape in which multiple rows of antenna elements are arranged (three rows in Figure 10). All antennas constituting the set are arranged at equal intervals. As a result, in the mode of transmitting the intermediate center frequency, the center position of the antenna with four rows of antenna elements becomes the equivalent antenna position.

[0052] In this case, in the medium frequency mode, the center position of the receiving antenna 4c is located off-center from the midpoint between the antenna position in the high frequency mode and the antenna position in the low frequency mode. As shown in Figure 11, when multiple receiving antennas 4b are arranged in rows, the antenna position in the medium frequency mode is closer to the antenna position in the low frequency mode.

[0053] As described above, the antenna position in the medium frequency mode is determined at least by the antenna configuration. In this embodiment, the directivity of the receiving antennas 4a and 4b can also be changed, as in the third embodiment described later.

[0054] (Third embodiment) As shown in Figure 12, the third embodiment is a modified version of the first embodiment.

[0055] In the third embodiment, the receiving antennas 4a and 4b in the antenna set have different antenna gain directivity characteristics. Specifically, as shown in Figure 10, one of the antennas (for example, the low-frequency side) has a shape in which multiple rows (for example, three rows) of antenna elements 40 are arranged. The rows of antenna elements 40 constituting the antenna set are arranged at equal intervals.

[0056] In this case, as shown in Figure 12, the receiving antenna 4a has directivity that allows it to obtain antenna gain over a wider azimuth range than the receiving antenna 4b. The receiving antenna 4b has directivity that allows it to obtain antenna gain over a longer distance than the receiving antenna 4a. The frequency characteristics of the antenna gain and the passthrough characteristics of the filter circuit for the receiving antennas 4a and 4b are assumed to be the same as in the first embodiment.

[0057] As a result, in the medium frequency mode, the received signal is equivalent to being received by a single receiving antenna 4c, which has a combined directivity of receiving antenna 4a and receiving antenna 4b. As shown in Figure 12, the combined directivity in the medium frequency mode is narrower and provides antenna gain over longer distances than the antennas on the high frequency side.

[0058] In other words, by having the MMIC5 perform frequency switching control, target detection processing becomes possible with different directivity for each mode. In this embodiment, the low-frequency mode enables wider-angle target detection at relatively close range. The high-frequency mode enables narrower-angle and longer-range target detection than the low-frequency mode. Furthermore, the medium-frequency mode enables even narrower-angle and longer-range target detection than the high-frequency mode. In short, the field of view and detection distance for target detection in the radar device 1 are changed by frequency switching control.

[0059] Alternatively, instead of receiving antennas 4a and 4b, the transmitting antenna 4 may be configured with the antenna set shown in Figure 10. In this case as well, since the transmission signal is transmitted with a radiation pattern corresponding to each directional characteristic, the field of view and detection distance for target detection in the radar device 1 are changed by frequency switching control, just as in the case of the receiving antenna.

[0060] (Other embodiments) Although several embodiments have been described above, this disclosure is not intended to be limited to those embodiments, and can be applied to various embodiments and combinations without departing from the spirit of this disclosure.

[0061] In the modified example, the transmitting antenna system 2 may include a set of transmitting antennas 4 with different frequency characteristics. Alternatively, the MMIC 5 may have multiple transmitting channels, and each transmitting channel may be connected to either a single transmitting antenna 4 or a set of transmitting antennas 4.

[0062] In the modified example, the dedicated computer constituting the controller 6 may have at least one of the digital circuit and analog circuit as a processor. Here, the digital circuit is at least one of the following, for example, ASIC (Application Specific Integrated Circuit), FPGA (Field Programmable Gate Array), SOC (System on a Chip), PGA (Programmable Gate Array), and CPLD (Complex Programmable Logic Device). Furthermore, such a digital circuit may have memory for storing programs.

[0063] In the modified examples, the mobile body to which the radar system 1 is applied may be, for example, an autonomous mobile robot capable of transporting goods or collecting information by autonomous or remote driving. In addition to the embodiments described so far, the above embodiments and modifications may be implemented in the form of a processing circuit (e.g., a processing ECU, etc.) or a semiconductor device (e.g., a semiconductor chip, etc.) as a control device configured to be mounted on a host mobile body and having at least one processor 3b and one memory 3a.

[0064] (Note) This specification discloses several technical concepts and several combinations thereof, as listed below.

[0065] (Technical thought 1) A transmitting antenna system (2) including an antenna that transmits a transmission signal, A receiving antenna system (3) including the antenna that receives the transmitted signal reflected from the outside as a received signal, A control unit (5) that outputs the transmission signal to the transmitting antenna system and acquires the reception signal from the receiving antenna system, Equipped with, At least one of the transmitting antenna system and the receiving antenna system includes a set of antennas with different peak gain frequencies. The control unit is A radar device that switches between a high-frequency mode that generates a transmission signal with a center frequency corresponding to the antenna with the higher peak frequency among the set of antennas, a low-frequency mode that generates a transmission signal with a center frequency corresponding to the antenna with the lower peak frequency, and a medium-frequency mode that generates a transmission signal with a center frequency that falls within the frequency range from the center frequency in the high-frequency mode to the center frequency in the low-frequency mode.

[0066] (Technical thought 2) The radar apparatus according to technical concept 1, wherein the control unit generates the transmission signal in the medium frequency mode, with the center frequency being the frequency at which the gains of each of the antennas within the frequency range coincide.

[0067] (Technical Thought 3) The aforementioned receiving antenna system is It includes multiple sets of the aforementioned antennas, A radar device according to technical concept 1 or technical concept 2, wherein the spacing between antennas with high peak frequencies and the spacing between antennas with low peak frequencies in a plurality of sets of antennas are arranged to be different.

[0068] (Technical Thought 4) The radar device according to any one of Technical Concepts 1 to 3, wherein each of the antennas in the set comprises the antennas having different gain directional characteristics.

[0069] (Technical Thought 5) The control unit is a radar device according to any one of Technical Concepts 1 to 4, which temporally switches between the high-frequency mode, the low-frequency mode, and the medium-frequency mode.

[0070] (Technical Thought 6) The control unit is a radar device according to any one of Technical Concepts 1 to 5, which temporally switches between the high-frequency mode, the low-frequency mode, and the medium-frequency mode depending on the driving scene of the vehicle on which it is installed. [Explanation of Symbols]

[0071] 1: Radar system, 2: Transmitting antenna system, 3: Receiving antenna system, 5: MMIC (Control Unit)

Claims

1. A transmitting antenna system (2) including an antenna that transmits a transmission signal, A receiving antenna system (3) including the antenna that receives the transmitted signal reflected from the outside as a received signal, A control unit (5) that outputs the transmission signal to the transmitting antenna system and acquires the reception signal from the receiving antenna system, Equipped with, At least one of the transmitting antenna system and the receiving antenna system includes a set of antennas with different peak gain frequencies. The control unit is The system switches between a high-frequency mode that generates a transmission signal with a center frequency corresponding to the antenna with the higher peak frequency among the antenna set, a low-frequency mode that generates a transmission signal with a center frequency corresponding to the antenna with the lower peak frequency, and a medium-frequency mode that generates a transmission signal with a center frequency that falls within the frequency range from the center frequency in the high-frequency mode to the center frequency in the low-frequency mode. The aforementioned receiving antenna system is It includes four sets of the aforementioned antennas, Each of the aforementioned antenna sets is a set consisting of an antenna with a relatively high peak frequency and an antenna with a relatively low peak frequency. A radar device in which the antennas with relatively high peak frequencies in a plurality of sets are spaced at equal intervals, and the antennas with relatively low peak frequencies are also spaced at equal intervals, the spacing between the antennas with relatively high peak frequencies and the spacing between the antennas with relatively low peak frequencies are different in magnitude, and the antennas with relatively high peak frequencies and the antennas with relatively low peak frequencies are arranged so that their arrangement is symmetrical in the direction of the antenna arrangement, and the center of the arrangement of the four antennas with relatively high peak frequencies coincides with the center of the arrangement of the four antennas with relatively low peak frequencies.

2. The radar apparatus according to claim 1, wherein the control unit generates the transmission signal in the medium frequency mode, the center frequency of which the gains of each of the antennas within the frequency range coincide.

3. The radar device according to claim 1, wherein each of the antennas in the set comprises an antenna with different gain directional characteristics.

4. The radar device according to claim 1, wherein the control unit switches between the high-frequency mode, the low-frequency mode, and the medium-frequency mode over time.

5. The radar device according to claim 1, wherein the control unit temporally switches between the high-frequency mode, the low-frequency mode, and the medium-frequency mode according to the driving scene of the vehicle on which it is installed.

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