Radar equipment, radar control methods, radar control programs

Abstract

To provide a radar device and others, capable of suppressing spread of a peak and alleviating a restriction for a chirp signal.SOLUTION: A radar device includes a processor, and transmits a plurality of signal sets including at least one of a chirp signal having a temporally-changing frequency for each transmission cycle. The processor is configured to execute transmission of the signal set in which a center frequency of the chirp signal monotonously changes for each signal set and a time-interval between the signal sets linearly and temporally changes. When a relative change ratio of the center frequency to a reference frequency for each signal set is taken as a frequency change ratio, and a relative change ratio of the time-interval to a reference interval for each signal set is taken as a time change ratio, the transmission of the signal set includes adjustment of the center frequency so that a ratio change ratio as a relative change ratio of the time change ratio to the frequency change ratio is within an allowable change ratio range in a specific time domain.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] This disclosure relates to radar technology. [Background technology]

[0002] Patent Document 1 discloses a radar system that transmits multiple chirp signals with varying center frequencies and acquires the chirp signals reflected by a target as received signals. In frequency analysis of the beat signal obtained by mixing the transmitted and received signals, when the center frequency of the chirp signal changes, a term that depends on the product of the center frequency of the chirp signal and the transmission time appears in the frequency of the beat signal. If this term is nonlinear with respect to the number of chirp signals in sequence, the peak of the target broadens. In order to make this term linear, the radar system adjusts the time interval of the chirp signals so that the magnitude of the relative change in time interval is at least twice the magnitude of the relative change in center frequency. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] German Patent No. 102020210079 Specification [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] However, the technology described in Patent Document 1 may require time adjustments with a higher precision than that achievable with the IC in the radar system. In this case, adjusting parameters other than the time interval in the chirp signal may be necessary to achieve the required time interval. Therefore, in the technology described in Patent Document 1, there is a risk that the constraints on parameters other than the time interval in the chirp signal will become stricter in order to suppress peak spread.

[0005] One of the issues addressed by this disclosure is to provide a radar system capable of suppressing peak spread and relaxing constraints on chirp signals. Another issue addressed by this disclosure is to provide a radar control method capable of suppressing peak spread and relaxing constraints on chirp signals. Yet another issue addressed by this disclosure is to provide a radar control program capable of suppressing peak spread and relaxing constraints on chirp signals. [Means for solving the problem]

[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 the present disclosure is a radar device having a processor (6b) that transmits a plurality of signal sets, each transmission cycle, each including at least one time-varying chirp signal, The processor is The transmission of signal sets in which the center frequency of the chirp signal changes monotonically for each signal set, and the time interval between signal sets changes linearly over time, This involves acquiring received data of the reflected signal that the chirp signal has reflected from an external target, It is configured to perform, Sending a signal set is The product of the time interval for each signal set represents the time range after a predetermined time has elapsed from the start of the transmission cycle. In a specific time period, It is linear with respect to the number of sequences in the chirp signal. This includes adjusting the center frequency.

[0008] A second aspect of the present disclosure is a radar control method performed by a processor (6b) to control a radar device (1) that transmits a plurality of signal sets, each transmission cycle, each including at least one time-varying chirp signal, The transmission of signal sets in which the center frequency of the chirp signal changes monotonically for each signal set, and the time interval between signal sets changes linearly over time, Obtaining reception data of a reflected signal obtained by reflecting a chirp signal from an external target, including Transmitting a signal set The product of the time interval for each signal set represents the time range after a predetermined time has elapsed from the start of the transmission cycle. In a specific time domain It is linear with respect to the number of sequences in the chirp signal. includes adjusting the center frequency as follows.

[0009] A third aspect of the present disclosure is a radar control program stored in a storage medium (6a) and executed by a processor (6b) for controlling a radar device (1) that transmits a plurality of signal sets including at least one chirp signal whose frequency changes with time for each transmission cycle, The instructions are causing a signal set in which the center frequency of the chirp signal changes monotonically for each signal set and the time interval between signal sets changes linearly with time to be transmitted, causing reception data of a reflected signal obtained by reflecting the chirp signal from an external target to be acquired, including Causing a signal set to be transmitted The product of the time interval for each signal set represents the time range after a predetermined time has elapsed from the start of the transmission cycle. In a specific time domain It is linear with respect to the number of sequences in the chirp signal. includes adjusting the center frequency as follows.

[0010] According to these first to third aspects, Product of the time interval for each signal set is adjusted in a specific time domain It is linear with respect to the number of sequences in the chirp signal. as follows, the center frequency of the chirp signal is adjusted. Therefore, it is possible to avoid the product of the time interval and the center frequency of the chirp signal from becoming non-linear within a specific time domain.Since the center frequency can be adjusted more finely compared to the time interval, by adjusting the center frequency Product of the time interval for each signal set is The number of chirp signals is linear with respect to the sequence of signals. it becomes easier to separate, and the constraints on parameters other than the center frequency can be relaxed. As described above, it is possible to suppress the spread of peaks and relax the constraints on chirp signals.

Brief Description of Drawings

[0011] [Figure 1] It is a schematic diagram showing the overall configuration of the radar device to which the first embodiment is applied. [Figure 2] This is a block diagram showing the functional configuration of the control unit according to the first embodiment. [Figure 3] This is a flowchart showing the radar control flow according to the first embodiment. [Figure 4] This graph shows an example of a chirp signal according to the first embodiment. [Figure 5] This graph shows an example of how the time interval changes for each chirp signal. [Figure 6] This graph shows an example of the change in center frequency for each chirp signal. [Figure 7] This graph shows an example of the rate of change in the ratio for each chirp signal. [Figure 8] This graph shows an example of a chirp signal according to the second embodiment. [Figure 9] This graph shows an example of a chirp signal according to the third embodiment. [Figure 10] This graph shows an example of a chirp signal according to the fourth embodiment. [Figure 11] This graph shows an example of a chirp signal according to the fifth embodiment. [Modes for carrying out the invention]

[0012] Hereinafter, several embodiments of this disclosure will be described with reference to the drawings. In each embodiment, the same reference numerals will be used for corresponding components, and redundant explanations may be omitted. Furthermore, if only a part of the configuration is described in each embodiment, the configuration of other embodiments described earlier may be applied to the other parts of that configuration. Moreover, not only the combinations of configurations explicitly stated in the description of each embodiment, but also the configurations of multiple embodiments may be partially combined even if not explicitly stated, as long as there are no particular problems with the combination.

[0013] (First Embodiment) A first embodiment of the present disclosure will be described with reference to Figures 1 to 7. The radar device 1 is mounted on a moving object such as a vehicle. The radar device 1 transmits a transmission signal, receives the transmission signal reflected by an object as a reception signal, and detects target information such as the distance to the target (which is the object that reflected the transmission signal), the relative speed to the target, and the orientation of the target.

[0014] Target information output from radar device 1 is input to the in-vehicle ECU (Electronic control unit) via an in-vehicle network such as CAN (Control Area Network®) and Ethernet®. Based on the target information of each acquired target, the in-vehicle ECU performs various processes for autonomous driving and advanced driver assistance of the vehicle.

[0015] Examples of processing based on target information include collision avoidance processing and warning processing. Collision avoidance processing is the process of controlling the vehicle to avoid collision with a target by controlling the braking system, steering system, etc., based on the target information of each target. Warning processing is the process of warning the driver of the possibility of collision with a target based on the target information of each target.

[0016] As shown in the basic configuration of Figure 1, the radar device 1 of this embodiment includes a clock oscillator 2a, a signal generation unit 2b, multiple transmission circuits 3, multiple transmission antennas TX, multiple receiving antennas RX, multiple receiving circuits 4, a control unit 6, and a housing unit 7. The radar device 1 is a so-called MIMO (Multiple-Input-Multiple-Output) radar that artificially increases the number of receiving antennas RX beyond the actual number by transmitting transmission signals from multiple transmission antennas TX.

[0017] The clock oscillator 2a generates a periodic clock signal. The clock oscillator 2a transmits the clock signal to the signal generation unit 2b and each receiving circuit 4. The signal generation unit 2b generates a modulated signal based on a control signal from the control unit 6, modulated at a modulation period corresponding to the clock signal. The modulated signal is, for example, a so-called chirp signal whose frequency changes over time. The modulated signal is distributed and output to each channel of the transmitting circuit 3 and the receiving circuit 4. In the following, the modulated signal output from the signal generation unit 2b to the transmitting circuit 3 will be referred to as the transmitted signal. The modulated signal output from the signal generation unit 2b to the receiving circuit 4 will be referred to as the local signal.

[0018] The transmitting circuit 3 and the receiving circuit 4 are each mainly composed of semiconductor integrated circuit devices such as MMICs (Monolithic Microwave Integrated Circuits). The transmitting circuit 3 is connected to the transmitting antenna TX and outputs a transmission signal to the transmitting antenna TX. For example, multiple transmitting circuits 3 are installed in one radar device 1. The transmitting circuit 3 is equipped with the same number of amplifiers 30 as the number of connected transmitting antennas TX. The amplifiers 30 amplify the transmission signal output from the signal generation unit 2b and output it to the corresponding transmitting antenna TX.

[0019] The transmitting antenna TX converts the electrical signal supplied as a transmission signal from the signal generation unit 2b into a radio wave signal and transmits it to the outside world. The transmitting antenna TX is composed of at least one antenna element. For example, the transmitting antenna TX is a patch antenna comprising multiple flat antenna elements. The antenna elements are arranged on the side opposite to the ground plate of a dielectric substrate, where the ground plate is provided on one side, so as to face the ground plate. The multiple antenna elements are connected, for example, in series by a feed line that supplies the electrical signal.

[0020] The receiving antenna RX receives radio signals, including the transmitted signal, that have been reflected by a target, which acts as a reflector in the external environment. The receiving antenna RX is connected to the corresponding receiving circuit 4.

[0021] The receiving antenna RX converts the received signal, which is a radio wave signal, into an electrical signal and outputs it to the corresponding receiving circuit 4. The receiving antenna RX is a patch antenna, for example, similar to the transmitting antenna TX, in which at least one antenna element is connected in series by a feed line.

[0022] The receiving circuit 4 is connected to the receiving antenna RX and acquires the received signal received by the receiving antenna RX. A single radar device 1 may have multiple receiving circuits 4. The receiving circuit 4 includes the same number of amplifiers 40, signal mixers 41, and AD converters 42 as the number of connected receiving antennas RX.

[0023] The amplifier 40 amplifies the received signal received by the receiving antenna RX and outputs it to the signal mixing unit 41. The signal mixing unit 41 generates a beat signal by mixing the local signal from the signal generation unit 2b with the received signal. 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 AD converter 42 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).

[0024] The AD converter 42 converts the filtered analog beat signal into a digital signal. The AD converter 42 acquires the clock signal output from the clock oscillator 2a, samples the beat signal at time intervals corresponding to the period of the clock signal, and digitizes it. The AD converter 42 sequentially outputs the digitized beat signal to the control unit 6.

[0025] The housing unit 7 is a housing that accommodates the transmitting antenna TX, receiving antenna RX, clock oscillator 2a, signal generation unit 2b, transmitting circuit 3, receiving circuit 4, and control unit 6. The housing unit 7 comprises a radome 7a and a case body 7b. The radome 7a is mainly formed of a transparent material that transmits millimeter-wave radio waves. The radome 7a is attached to the case body 7b so as to cover the antennas TX and RX. The radome 7a protects the antennas TX and RX while enabling the transmission and reception of signals at the antennas TX and RX by transmitting radio waves. The case body 7b, together with the radome 7a, partitions the housing space for housing the components of the radar device 1 described above. A temperature sensor for detecting the internal temperature may be provided inside the housing unit 7. The temperature sensor may, for example, include a thermistor and output temperature information according to the resistance value of the thermistor. The temperature sensor may be configured to detect temperature information for each transmitting circuit 3 and receiving circuit 4 and output it to the control unit 6.

[0026] The control unit 6 is a control unit comprising at least one dedicated computer. The dedicated computer comprising the control unit 6 may be, for example, an ECU (Electronic Control Unit) specifically designed for controlling the radar device 1.

[0027] The dedicated computer constituting the control unit 6 has at least one memory 6a and one processor 6b. The memory 6a is at least one type of non-transitory tangible storage medium, such as a semiconductor memory, magnetic medium, and optical medium, which non-temporarily stores programs and data that can be read by the computer. Here, storage may be accumulation in which data is retained even when the sensor system is turned off, or it may be temporary storage in which data is erased when the sensor system is turned off.

[0028] The processor 6b may include at least one of the following as its core: a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), a RISC (Reduced Instruction Set Computer)-CPU, a DFP (Data Flow Processor), and a GSP (Graph Streaming Processor). Alternatively, the processor 6b may include at least one of a digital circuit and an analog circuit. Here, a digital circuit is at least one of the following: an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), a SOC (System on a Chip), a PGA (Programmable Gate Array), and a CPLD (Complex Programmable Logic Device). Such a digital circuit may also have a memory 6a that stores a program.

[0029] In radar device 1, processor 6b executes multiple instructions contained in the radar control program stored in memory 6a to detect targets. This allows radar device 1 to construct multiple functional units for controlling the radar. These functional units, as shown in Figure 2, include a transmission processing unit 60 and a reception processing unit 61. These functional units can also be referred to as functional blocks.

[0030] The radar control method, in which the control unit 6 controls the radar device 1 through the joint efforts of the transmission processing unit 60 and the reception processing unit 61, is executed according to the radar control flow shown in Figure 3. This radar control flow is executed repeatedly while the radar device 1 is running. In this radar control flow, each "S" represents a set of steps executed by multiple instructions included in the radar control program.

[0031] First, in S10, the transmission processing unit 60 generates and transmits a transmission signal. The transmission signal is a radar wave in the millimeter wave band or quasi-millimeter wave band. The transmission processing unit 60 generates a chirp wave, which is a frequency modulated in time, as the fundamental signal. Specifically, as shown in Figure 4, the transmission processing unit 60 defines one chirp as a waveform that changes (for example, gradually increases) from a predetermined initial frequency to a final frequency, and generates a signal in which multiple chirps are repeated at a predetermined period. The transmission processing unit 60 then transmits the multiple chirp signals thus generated as the transmission signal.

[0032] The transmission processing unit 60 generates multiple chirp signals in one transmission cycle. The transmission processing unit 60 sets the center frequency of each chirp signal to change monotonically in one transmission cycle. In the example shown in Figure 4, the transmission processing unit 60 sets the center frequency of each chirp signal so that the center frequency increases monotonically as time progresses in the transmission cycle. Here, a transmission cycle is defined as a specified number of transmission cycles (k) starting from the start of transmission of the first chirp signal. fin This is the cycle until the transmission of the chirp signal (individual) is completed.

[0033] The transmission processing unit 60 sets the time interval of the chirp signals to change linearly with respect to time and the number of chirp signals in the sequence. Here, the time interval of a particular chirp signal is the interval between the start time of transmission of that signal and the start time of transmission of the chirp signal that precedes it within the transmission cycle. Here, for the kth chirp signal in a given transmission cycle, the start time of transmission is set to T S (k), time interval T D Let (k) be the time interval. Since there is no preceding chirp signal for the first chirp signal, the time interval from the reference time is set to T. DS Let's assume that. DS This is, for example, set to zero. Time interval T D If Δt is the increase in each chirp signal of (k), then the time interval T changes linearly. D (k) is T DS This corresponds to the following equation (1) using k and Δt. [Number]

[0034] Then, the transmission processing unit 60 sets the transmission start time T S (k) corresponding to the following mathematical formula (2) for the k-th chirp signal. [Number]

[0035] For each chirp signal with a specified number in one transmission cycle, the transmission processing unit 60 sets the time interval T D (k) and the transmission start time T S (k) for transmission. Further, the transmission processing unit 60 defines a monotonically changing center frequency as a parameter for each chirp signal in one transmission cycle.

[0036] For the center frequency F S (k) of the k-th chirp signal, the transmission processing unit 60 sets it to a frequency such that the product of the time interval T D (k) and the center frequency is substantially linear with respect to time and the order number of the chirp signals in a specific time domain. Here, "substantially linear" means that the relative change rate of the frequency change rate (which is the relative change rate of the center frequency with respect to the reference frequency) with respect to the relative change rate of the time change rate (which is the relative change rate of the time interval T D (k) with respect to the reference interval) falls within the allowable change rate range. In the following, the relative change rate of the time change rate with respect to the frequency change rate may be referred to as the ratio change rate. Here, the allowable change rate range is the range where the ratio change rate is less than or equal to the specified upper threshold value or less than, and greater than or equal to the specified lower threshold value or more than. Also, the specific time domain is the time domain where the time is less than or equal to the specified upper time limit or less than, and greater than or equal to the specified lower time limit or more than. For example, the specific time domain is the time domain after a predetermined time has elapsed from the start of the transmission cycle, that is, the time domain where the upper time limit is the predetermined time and the lower time limit is zero.

[0037] Here, the time rate of change A and frequency rate of change B of the k-th chirp signal correspond to the values ​​calculated by the following equations (3) and (4). Note that the reference interval for the time rate of change A is the first time interval T. DS The reference frequency at frequency change rate B is the first center frequency F. SS Let's assume that.

number

number

[0038] Therefore, the ratio change rate corresponds to the value obtained by dividing the right-hand side of equation (3) by the right-hand side of equation (4). The transmission processing unit 60 determines the center frequency F such that this ratio change rate falls within the allowable rate of change range in a specific time range. S (k) is defined. For example, the time interval T D Let (k) be the change pattern shown in the graph in Figure 5. In this case, the transmission processing unit 60 will set the center frequency F S (k) is varied for each chirp signal so that the rate of change of the ratio is as shown in the graph in Figure 7, according to the change pattern shown in the graph in Figure 6. This center frequency F S (k) is the time interval T D (k) and consequently the transmission start time T S The parameter that corresponds to the value whose product with (k) is essentially linear is expressed by the following equation (5).

number

[0039] Here, the rate of change in the ratio from the subsequent chirp signal to the preceding chirp signal in each transmission cycle is in only one direction: negative. That is, the graph of the rate of change in the ratio in one transmission cycle is one of only two inverse hyperbolas, as shown in Figure 7. For this reason, the transmission processing unit 60 manages the number of each chirp signal within one transmission cycle to start from k=1.

[0040] Furthermore, the ICs that make up the control unit 6 generally allow for adjustment of the time interval in increments of approximately 10 ns. In addition, the center frequency of these ICs generally allows for adjustment in increments of commahertz.

[0041] In the first embodiment, the transmission processing unit 60 generates a transmission signal in which the time interval changes linearly with respect to time and the number of chirp signals in sequence, and the center frequency changes monotonically for each chirp signal. That is, the transmission processing unit 60 can be understood as generating a transmission signal in which a single chirp signal is treated as a signal set, and the time interval changes linearly for each signal set, and the center frequency changes monotonically. The time width from the start to the end of transmission of a chirp signal within a transmission cycle, and the size of the bandwidth are set to be substantially the same, for example. Also, the end time of transmission of a preceding chirp signal and the start time of transmission of a subsequent chirp signal are set to be substantially the same.

[0042] Next, in S20, the transmission processing unit 60 receives the signal that has been reflected back from the target as the received signal. In the following S30, the reception processing unit 61 acquires a beat signal corresponding to the received signal.

[0043] Then, in S40, the receiving processing unit 61 obtains target information about the target by performing frequency analysis on the beat signal. The target information includes at least the distance and relative velocity of the target to the radar device 1. Specifically, the receiving processing unit 61 performs two FFT (Fast Fourier Transform) operations on the beat signal. As a result, the transmitting processing unit 60 obtains a two-dimensional spectrum relating to distance and relative velocity.

[0044] More specifically, the transmission processing unit 60 first performs an FFT (Fast-Fast Transform) on the beat signal for each chirp. This first FFT process yields a frequency spectrum (distance spectrum) for each chirp, showing a peak at a frequency corresponding to the distance to the target. The distance spectrum is considered data that shows the signal intensity for each distance bin according to the distance resolution.

[0045] When the relative velocity to the target is not zero, the distance spectrum corresponding to each chirp shows a peak in the same distance bin, but the phases differ between chirps. This phase difference between chirps is due to the change in distance between the radar device 1 and the target. This is used to detect the relative velocity to the target in the FCM (Fast Chirp Modulation) method. Through these two FFT processes, the transmission processing unit 60 obtains a two-dimensional spectrum for distance and relative velocity.

[0046] Specifically, as the second FFT processing, the receiving processing unit 61 performs FFT processing on a waveform obtained by arranging the phases in the distance bins obtained in the first FFT processing on multiple chirps in a time series. This yields a frequency spectrum (velocity spectrum) with a peak at a position corresponding to the relative velocity with the target, for each velocity bin. Depending on the maximum detection velocity, velocity aliasing may occur, and multiple peaks may be shown in the two-dimensional spectrum.

[0047] Here, the frequency φ at a specific sampling point for each chirp signal, which can be obtained by the second FFT process, is obtained. IF (k) corresponds to the following formula, where r is the distance to the target, v is the velocity, and c is the speed of light. Note that in the following, s ch This parameter is determined by the slope of the chirp signal, with a value of +1 for a positive slope and -1 for a negative slope.

number

[0048] Here, the transmission signal processing in the transmission processing unit 60 determines the center frequency F S (k) and time interval T D The product with (k) is substantially linear. Transmission start time T S (k) is the time interval T to the kth chirp signal. D Since it is the sum of (k), the transmission start time T S (k) and center frequency F SThe product with (k) is also linear. That is, the center frequency F in the second term of equation (6) above. S (k) and transmission start time T S (k) and F S The product with (k) is also linear. Therefore, compared to the case where this product is nonlinear, the peak spread is more easily suppressed even when the target velocity increases.

[0049] The receiving processing unit 61 acquires the target distance and relative velocity as target information based on the results of the second FFT processing. In the subsequent S50, the receiving processing unit 61 outputs the acquired target information. The output process of the target information includes the process of transmitting the target information to an external source and the process of storing it in a storage medium.

[0050] Furthermore, the direction of the object to be detected can be determined based on the direction of beam irradiation. In addition, if the receiving unit 12 is equipped with multiple receiving antennas RX, the direction may be detected based on the phase difference of the received signals between the receiving antennas RX. The radar device 1 outputs the detected object information to an operation control ECU (Electronic Control Unit) or the like that controls the operation of the vehicle.

[0051] According to the first embodiment described above, the center frequency of the chirp signal is adjusted so that the ratio change rate falls within an acceptable range of change rate in a specific time range. Therefore, it is possible to avoid the product of the time interval and the center frequency of the chirp signal becoming nonlinear within a specific time range. Since the center frequency can be adjusted more finely than the time interval, adjusting the center frequency makes it easier to keep the ratio change rate within an acceptable range of change rate, and the constraints on parameters other than the center frequency can be relaxed. As a result, it is possible to suppress the spread of peaks and relax the constraints on the chirp signal.

[0052] (Second embodiment) As shown in Figure 8, the second embodiment is a modification of the first embodiment.

[0053] In the second embodiment, the transmission processing unit 60 switches between increasing and decreasing the frequency of each chirp signal over time, depending on the transmission cycle. In other words, the transmission processing unit 60 changes the sign of the slope of the frequency change over time for each chirp signal according to the transmission cycle. For example, as shown in Figure 8, the transmission processing unit 60 sets the slope of the frequency change to the positive direction in a particular transmission cycle, and then switches the slope of the frequency change to the negative direction in the immediately following transmission cycle.

[0054] According to the second embodiment described above, the frequency of the chirp signal switches between increasing and decreasing over time depending on the transmission cycle, thereby suppressing interference with other radar devices 1.

[0055] (Third embodiment) As shown in Figure 9, the third embodiment is a modified version of the first embodiment.

[0056] In the third embodiment, the transmission processing unit 60 switches between increasing and decreasing the center frequency of each chirp signal over time, depending on the transmission cycle. In other words, the transmission processing unit 60 changes the sign of the slope of the center frequency change over time for the entire transmission cycle, depending on the transmission cycle. For example, as shown in Figure 9, the transmission processing unit 60 sets the slope of the center frequency change to the positive direction in a particular transmission cycle, and then switches the slope of the center frequency change to the negative direction in the transmission cycle immediately following it.

[0057] According to the third embodiment described above, the center frequency of each chirp signal switches between increasing and decreasing over time depending on the transmission cycle, thereby suppressing interference with other radar devices 1.

[0058] (Fourth embodiment) As shown in Figure 10, the fourth embodiment is a modification of the first embodiment.

[0059] The transmission processing unit 60 performs both switching between increasing and decreasing the center frequency of each chirp signal over time according to the transmission cycle, and switching between increasing and decreasing the center frequency of each chirp signal over time according to the transmission cycle. For example, as shown in Figure 10, the transmission processing unit 60 sets the slope of the frequency change for each chirp signal to the positive direction and the slope of the center frequency change to the negative direction in a particular transmission cycle. Then, in the transmission cycle immediately following, the transmission processing unit 60 switches the slope of the frequency change for each chirp signal to the negative direction and the slope of the center frequency change to the positive direction.

[0060] (Fifth embodiment) As shown in Figure 11, the fifth embodiment is a modification of the first embodiment.

[0061] In the fifth embodiment, the transmission processing unit 60 sets the time interval and center frequency of the chirp signals within the transmission cycle to change for each set of multiple chirp signals. In the example shown in Figure 11, the transmission processing unit 60 sets the time interval and center frequency to change for each set of two consecutive chirp signals.

[0062] According to the fifth embodiment described above, the center frequency and time interval change for each set of multiple chirp signals, rather than for each individual chirp signal. This makes it possible to adjust the time interval to a smaller value compared to when the interval is changed for each individual chirp signal. For example, if the minimum time interval that can be set in the control unit 6 is 10 ns, then if an adjustment of 5 ns is required, this can be handled by changing the interval every other time. When there is a difference between the required time interval and the time interval that can be implemented, finer time interval control becomes possible by changing the time interval for each set of multiple chirp signals as described above.

[0063] (Other embodiments) Although several embodiments have been described above, this disclosure is not limited to those embodiments and can be applied to various embodiments and combinations without departing from the spirit of this disclosure.

[0064] In the modified example, the time interval T D (k) may be the interval between representative times in the chirp signal other than the transmission start time. A representative time other than the transmission start time is, for example, the transmission end time of the chirp signal, with a center frequency F. S This is the time, etc., when (k) occurs.

[0065] In the modified example, the direction of change in the ratio from the subsequent chirp signal to the preceding chirp signal in each transmission cycle may be limited to only one direction, the positive direction.

[0066] In the modified example, the time interval T of the chirp signal D (k) and center frequency F S Parameters other than (k) may be changed as appropriate. Also, the preceding chirp signal and the following chirp signal may be separated in time, or they may partially overlap in time.

[0067] In the modified example, the radar device 1 may perform so-called CDM (Code Division Multiplex) modulation, in which a random component is superimposed on the phase of the chirp signal to be transmitted for each of the multiple transmitting antennas TX.

[0068] In the modified example, the radar device 1 may perform so-called DDM (Doppler Division Multiplex) modulation, in which a linear component is superimposed on the phase of the chirp signal to be transmitted for each of the multiple transmitting antennas TX.

[0069] In the modified example, the mobile body to which the radar device 1 is applied may be, for example, an autonomous robot capable of transporting cargo or collecting information by autonomous or remote driving. Furthermore, the autonomous robot may also include an autonomous vehicle.

[0070] In addition to the embodiments described so far, the above-described embodiments and modifications may be implemented as control devices configured to be mounted on a host mobile device and having at least one processor 6b and one memory 6a. Specifically, the above-described embodiments and modifications may be implemented in the form of a processing circuit (e.g., a processing ECU) or a semiconductor device (e.g., a semiconductor chip).

[0071] (Disclosure of technical ideas) This specification discloses several technical concepts, as described in the following paragraphs. Some paragraphs are written in a multiple dependent form, where subsequent paragraphs optionally refer to preceding paragraphs. Furthermore, some paragraphs are written in a multiple dependent form, referring to other multiple dependent forms. These paragraphs written in multiple dependent forms define several technical concepts.

[0072] (Technical thought 1) A radar device having a processor (6b) that transmits multiple signal sets, each transmission cycle, each including at least one chirp signal whose frequency varies over time, The aforementioned processor, The transmission of the signal set wherein the center frequency of the chirp signal changes monotonically for each signal set, and the time interval between the signal sets changes linearly over time. The process involves acquiring received data of the reflected signal that the chirp signal has reflected from an external target, It is configured to perform, Transmitting the aforementioned signal set means A radar device that includes adjusting the center frequency such that, when the frequency rate of change is defined as the relative rate of change of the center frequency for each signal set with respect to a reference frequency, and the time rate of change is defined as the relative rate of change of the time interval for each signal set with respect to a reference interval, the ratio rate of change, which is the relative rate of change of the time rate of change with respect to the frequency rate of change, falls within an allowable rate of change range in a specific time range.

[0073] (Technical thought 2) The radar device according to Technical Concept 1, wherein the signal set has a signal set in which the direction of change of the ratio from the subsequent signal set to the preceding signal set in each transmission cycle is in only one direction, either positive or negative.

[0074] (Technical Thought 3) The radar device according to Technical Concept 1 or Technical Concept 2 transmits the signal set, which switches between increasing and decreasing the frequency of the chirp signal over time according to the transmission cycle.

[0075] (Technical Thought 4) The radar device according to any one of Technical Concepts 1 to 3, wherein transmitting the signal set involves switching between increasing and decreasing changes in the center frequency of each signal set according to the transmission cycle.

[0076] (Technical Thought 5) A radar device according to any one of Technical Ideas 1 to 4, wherein transmitting the signal set includes transmitting a single chirp signal for each signal set.

[0077] (Technical Thought 6) A radar device according to any one of Technical Ideas 1 to 4, wherein transmitting the signal set includes transmitting a plurality of chirp signals for each signal set.

[0078] Furthermore, the above technical concepts may be implemented in the form of radar control methods and radar control programs. [Explanation of Symbols]

[0079] 1: Radar device, 6a: Memory (storage medium), 6b: Processor

Claims

1. A radar device having a processor (6b) that transmits multiple signal sets, each transmission cycle, each including at least one chirp signal whose frequency varies over time, The aforementioned processor, The transmission of the signal set wherein the center frequency of the chirp signal changes monotonically for each signal set, and the time interval between the signal sets changes linearly over time. The process involves acquiring received data of the reflected signal that the chirp signal has reflected from an external target, It is configured to perform, Transmitting the aforementioned signal set means A radar device that includes adjusting the center frequency such that the product of the time interval for each signal set is linear with respect to the number of sequences of the chirp signals in a specific time range which is a time range after a predetermined time has elapsed from the start of the transmission cycle.

2. If the relative rate of change of the center frequency for each signal set with respect to the reference frequency is defined as the frequency rate of change, the relative rate of change of the time interval for each signal set with respect to the reference interval is defined as the time rate of change, and the relative rate of change of the time rate of change with respect to the frequency rate of change is defined as the ratio rate of change, The radar device according to claim 1, wherein the signal set has a signal set in which the direction of change of the ratio from the subsequent signal set to the preceding signal set in each transmission cycle is in only one direction, either positive or negative.

3. The radar device according to claim 1, wherein transmitting the signal set involves switching between a time-dependent increase and decrease in the frequency of the chirp signal according to the transmission cycle.

4. The radar device according to claim 1, wherein transmitting the signal set involves switching between an increasing change and a decreasing change in the center frequency of each signal set according to the transmission cycle.

5. The radar apparatus according to claim 1, wherein transmitting the signal set comprises transmitting a single chirp signal for each signal set.

6. The radar apparatus according to claim 1, wherein transmitting the signal set includes transmitting a plurality of chirp signals for each signal set.

7. A radar control method performed by a processor (6b) to control a radar device (1) that transmits multiple signal sets, each transmission cycle, including at least one time-varying chirp signal, the radar device (1) comprising: The transmission of the signal set wherein the center frequency of the chirp signal changes monotonically for each signal set, and the time interval between the signal sets changes linearly over time. The process involves acquiring received data of the reflected signal that the chirp signal has reflected from an external target, Includes, Transmitting the aforementioned signal set means A radar control method that includes adjusting the center frequency such that the product of the time interval for each signal set is linear with respect to the number of sequences of the chirp signals in a specific time range which is a time range after a predetermined time has elapsed from the start of the transmission cycle.

8. A radar control program, which includes instructions to be executed by a processor (6b) and is stored in a storage medium (6a) for controlling a radar device (1) that transmits multiple signal sets, each transmission cycle, each including at least one chirp signal with a time-varying frequency, The aforementioned instruction is, The transmission of the signal set wherein the center frequency of the chirp signal changes monotonically for each signal set, and the time interval between the signal sets changes linearly over time. The chirp signal is used to acquire received data of the reflected signal that has been reflected by an external target, Includes, Transmitting the aforementioned signal set means A radar control program that includes adjusting the center frequency such that the product of the time interval for each signal set is linear with respect to the number of sequences of the chirp signals in a specific time range that is a time range after a predetermined time has elapsed from the start of the transmission cycle.

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