Radar device, radar control method and radar control program

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 a beat signal generated by mixing a transmitted signal with a received signal, if the center frequency of the chirp signal varies, 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 sequential orders of the chirp signal, the target peak will broaden. To make this term linear, the radar system adjusts the time interval of the chirp signal so that the magnitude of the relative change in the time interval is at least twice the magnitude of the relative change in the center frequency. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] German Patent No. 102020210079 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the technique of Patent Document 1 may require more precise time adjustment than can be realized by the IC of the radar system. In this case, it may be necessary to adjust parameters other than the time interval in the chirp signal in order to realize the required time interval. Therefore, the technique of Patent Document 1 may impose stricter constraints on parameters other than the time interval in the chirp signal in order to suppress the broadening of the peak.

[0005] An object of the present disclosure is to provide a radar device capable of suppressing peak broadening and relaxing restrictions on chirp signals.Another object of the present disclosure is to provide a radar control method capable of suppressing peak broadening and relaxing restrictions on chirp signals.A further object of the present disclosure is to provide a radar control program capable of suppressing peak broadening and relaxing restrictions on chirp signals. [Means for solving the problem]

[0006] The technical means of the present disclosure for solving the problems will be described below. Note that the claims and the reference characters in parentheses in this section indicate the corresponding relationship with the specific means described in the embodiments described later in detail, and do not limit the technical scope of the present disclosure.

[0007] A first aspect of the present disclosure is a radar device having a processor (6b) and configured to transmit a plurality of signal sets each including at least one chirp signal whose frequency varies over time, for each transmission cycle, the radar device comprising: The processor Transmitting sets of signals, each set having a monotonically varying center frequency of a chirp signal and a linearly time varying time interval between the sets of signals; Obtaining received data of a reflected signal of the chirp signal reflected by a target in the outside world; configured to run Transmitting a signal set includes: The method includes adjusting the center frequency so that a ratio rate of change, which is the relative rate of change of the time rate of change to the frequency rate, in a specific time domain falls within an allowable rate of change range, where the frequency rate of change is 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 the relative rate of change of the time rate of change to the frequency rate.

[0008] A second aspect of the present disclosure is a radar control method executed by a processor (6b) to control a radar device (1) that transmits a signal set including at least one chirp signal whose frequency varies over time in each transmission cycle, the method comprising: Transmitting sets of signals, each set having a monotonically varying center frequency of a chirp signal and a linearly time varying time interval between the sets of signals; Obtaining received data of a reflected signal of the chirp signal reflected by a target in the outside world; Including, Transmitting a signal set includes: The method includes adjusting the center frequency so that a ratio rate of change, which is the relative rate of change of the time rate of change to the frequency rate, in a specific time domain falls within an allowable rate of change range, where the frequency rate of change is 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 the relative rate of change of the time rate of change to the frequency rate.

[0009] A third aspect of the present disclosure provides a radar control program for controlling a radar device (1) that transmits a plurality of signal sets, each signal set including at least one chirp signal whose frequency varies over time, in each transmission cycle, the radar control program including instructions to be executed by a processor (6b), the program including: The command is, transmitting sets of signals, the center frequency of the chirp signal varying monotonically for each set of signals and the time interval between the sets of signals varying linearly over time; Acquiring reception data of a reflected signal of the chirp signal reflected by a target in the outside world; Including, To transmit a set of signals: The method includes adjusting the center frequency so that a ratio rate of change, which is the relative rate of change of the time rate of change to the frequency rate, in a specific time domain falls within an allowable rate of change range, where the frequency rate of change is the relative rate of change of the center frequency for each signal set to a reference frequency, and the time rate of change is the relative rate of change of the time interval for each signal set to a reference interval.

[0010] According to the first to third aspects, the center frequency of the chirp signal is adjusted so that the ratio change rate falls within the allowable change rate range in a specific time domain. Therefore, it is possible to prevent the product of the time interval and the center frequency of the chirp signal from becoming nonlinear within the specific time domain. Since the center frequency can be adjusted more finely than the time interval, the ratio change rate can be more easily brought within the allowable change rate range by adjusting the center frequency, and the constraints on parameters other than the center frequency can be relaxed. As a result, it is possible to suppress the broadening of the peak and relax the constraints on the chirp signal. [Brief description of the drawings]

[0011] [Figure 1] 1 is a schematic diagram showing an overall configuration of a radar device to which a first embodiment is applied; [Diagram 2] FIG. 2 is a block diagram showing a functional configuration of a control unit according to the first embodiment. [Diagram 3] 4 is a flowchart showing a radar control flow according to the first embodiment. [Figure 4] 4 is a graph showing an example of a chirp signal according to the first embodiment. [Diagram 5] 1 is a graph showing an example of changes in time intervals for each chirp signal. [Figure 6] 1 is a graph showing an example of a change in center frequency for each chirp signal. [Figure 7] 11 is a graph showing an example of a ratio change rate for each chirp signal. [Figure 8] 10 is a graph showing an example of a chirp signal according to the second embodiment. [Figure 9] 13 is a graph showing an example of a chirp signal according to the third embodiment. [Figure 10] 13 is a graph showing an example of a chirp signal according to the fourth embodiment. [Figure 11] 13 is a graph showing an example of a chirp signal according to the fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, multiple embodiments of the present disclosure will be described with reference to the drawings. In addition, by assigning the same reference numerals to corresponding components in each embodiment, duplicated descriptions may be omitted. In addition, when only a part of the configuration is described in each embodiment, the configuration of the other embodiment described above can be applied to the other parts of the configuration. Furthermore, in addition to the combination of configurations explicitly stated in the description of each embodiment, configurations of multiple embodiments can be partially combined together even if not explicitly stated, as long as there is no particular problem with the combination.

[0013] First embodiment A first embodiment of the present disclosure will be described with reference to Fig. 1 to Fig. 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 received signal, and detects, as target information, the distance to a target that is the object that reflected the transmission signal, the relative speed with respect to the target, the direction of the target, and the like.

[0014] The target information output from the radar device 1 is input to an in-vehicle ECU (Electronic control unit) via an in-vehicle network such as a Control Area Network (CAN) (registered trademark) or Ethernet (registered trademark). The in-vehicle ECU executes various processes for automatic driving of the vehicle and advanced driving assistance based on the acquired target information of each target.

[0015] The processes based on the target information include, for example, collision avoidance process, warning process, etc. The collision avoidance process is a process of performing vehicle control to avoid collision with the target by controlling the brake system, steering system, etc. based on the target information of each target. The warning process is a process of warning the driver of the possibility of collision with the target based on the target information of each target.

[0016] 1, the radar device 1 of this embodiment includes a clock oscillator 2a, a signal generating unit 2b, multiple transmission circuits 3, multiple transmission antennas TX, multiple receiving antennas RX, multiple receiving circuits 4, a control unit 6, and a storage unit 7. The radar device 1 is a so-called MIMO (Multiple-Input-Multiple-Output) type radar that transmits transmission signals from multiple transmission antennas TX to artificially increase the number of receiving antennas RX beyond the actual number.

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

[0018] The transmitting circuit 3 and the receiving circuit 4 are each mainly composed of a semiconductor integrated circuit device such as an MMIC (Monolithic Microwave Integrated Circuit). The transmitting circuit 3 is connected to a transmitting antenna TX and outputs a transmitting signal to the transmitting antenna TX. For example, a plurality of transmitting circuits 3 are mounted on one radar device 1. The transmitting circuit 3 includes amplifiers 30 in the same number as the connected transmitting antennas TX. The amplifiers 30 amplify the transmitting signals output from the signal generating unit 2b and output the signals to the corresponding transmitting antennas TX.

[0019] The transmitting antenna TX converts an electric signal, which is a transmission signal supplied from the signal generating unit 2b, into a radio wave signal and transmits the signal to the outside world. The transmitting antenna TX includes at least one antenna element. For example, the transmitting antenna TX is a patch antenna including a plurality of flat antenna elements. The antenna element is disposed on a surface of a dielectric substrate having a ground plane on one side thereof, opposite the ground plane, so as to face the ground plane. The plurality of antenna elements are connected, for example, in series, by a feeder line that supplies an electric signal.

[0020] The receiving antenna RX receives, as a received signal, a radio wave signal including a transmission signal reflected by a target in the outside world as a reflecting object. The receiving antenna RX is connected to a corresponding receiving circuit 4.

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

[0022] The receiving circuit 4 is connected to the receiving antenna RX and acquires a signal received by the receiving antenna RX. For example, a plurality of receiving circuits 4 are mounted on one radar device 1. The receiving circuit 4 includes amplifiers 40, signal mixers 41, and AD converters 42, the number of which is the same as the number of connected receiving antennas RX.

[0023] The amplifier 40 amplifies the reception signal received by the reception antenna RX and outputs the amplified signal to the signal mixer 41. The signal mixer 41 generates a beat signal by mixing the reception signal with the local signal from the signal generating unit 2b. The generated beat signal is an interference signal that represents the frequency difference between the reception 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 reception signal and the local signal have been filtered out by a low-pass filter (not shown).

[0024] The AD converter 42 converts the beat signal, which is a filtered analog 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 according to the cycle of the clock signal, and digitizes it. The AD converter 42 sequentially outputs the digitized beat signal to the control unit 6.

[0025] The accommodation unit 7 is a housing that houses the transmitting antenna TX, the receiving antenna RX, the clock oscillator 2a, the signal generating unit 2b, the transmitting circuit 3, the receiving circuit 4, and the control unit 6. The accommodation unit 7 includes a radome 7a and a case body 7b. The radome 7a is mainly formed of a transparent material that transmits radio waves in the millimeter wave band. 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 allowing radio waves to pass through to enable transmission and reception of signals at the antennas TX and RX. The case body 7b, together with the radome 7a, defines an accommodation space that houses the components of the radar device 1 described above. A temperature sensor that detects the internal temperature may be provided inside the accommodation unit 7. The temperature sensor includes, for example, a thermistor, and outputs temperature information according to the resistance value of the thermistor. The temperature sensor may be configured to detect temperature information of each of the transmitting circuit 3 and the receiving circuit 4 and output the information to the control unit 6.

[0026] The control unit 6 is a control unit including at least one dedicated computer. The dedicated computer constituting the control unit 6 may be, for example, an ECU (Electronic Control Unit) specialized 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, a magnetic medium, or an optical medium, that non-temporarily stores computer-readable programs and data. Here, storage may be accumulation in which data is retained even when the sensor system is turned on or off, or temporary storage in which data is erased when the sensor system is turned on or off.

[0028] The processor 6b may include at least one of a central processing unit (CPU), a graphics processing unit (GPU), a reduced instruction set computer (RISC)-CPU, a data flow processor (DFP), and a graph streaming processor (GSP) as a core. Alternatively, the processor 6b may be at least one of a digital circuit and an analog circuit. Here, the digital circuit is at least one of an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a system on a chip (SOC), a programmable gate array (PGA), and a complex programmable logic device (CPLD). Such a digital circuit may also have a memory 6a that stores a program.

[0029] In the radar device 1, the processor 6b executes a plurality of instructions included in a radar control program stored in the memory 6a in order to detect a target. In this way, the radar device 1 configures a plurality of functional units for controlling the radar. The functional units configured in the radar device 1 include a transmission processing unit 60 and a reception processing unit 61 as shown in Fig. 2. These functional units may also be referred to as functional blocks.

[0030] The radar control method in which the control unit 6 controls the radar device 1 through cooperation between the transmission processing unit 60 and the reception processing unit 61 is executed according to the radar control flow shown in Fig. 3. This radar control flow is executed repeatedly while the radar device 1 is running. Note that each "S" in this radar control flow represents multiple steps executed by multiple commands 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 whose frequency is modulated over time as a basic signal. Specifically, as shown in FIG. 4, the transmission processing unit 60 regards a waveform that changes (e.g., gradually increases) from a predetermined initial frequency to a final frequency as one chirp, and generates a signal that repeats multiple chirps at a predetermined period. The transmission processing unit 60 transmits the multiple chirp signals thus generated as transmission signals.

[0032] The transmission processing unit 60 generates multiple chirp signals in one transmission cycle. The transmission processing unit 60 sets the center frequency of the chirp signal to change monotonically in one transmission cycle. In the example shown in FIG. 4, the transmission processing unit 60 sets the center frequency of each chirp signal so that the center frequency increases monotonically with the passage of time in the transmission cycle. Note that the transmission cycle here refers to a specific number of transmissions (k fin The number of cycles required to transmit a chirp signal (number of chirp signals) is called the cycle.

[0033] The transmission processing unit 60 sets the time interval of the chirp signals to change linearly with time and the number of sequential orders of the chirp signals. Here, the time interval of a particular chirp signal is the interval between the transmission start time of the particular signal and the transmission start time of the chirp signal immediately preceding the particular signal within the transmission cycle. Here, the transmission start time of the kth chirp signal in a certain transmission cycle is set as T S (k), the time interval is T D (k). Since there is no preceding chirp signal for the first chirp signal, the time interval from the reference time is T DS Let us assume that T DS is set to zero, for example. D If the increment for each chirp signal in (k) is Δt, the linearly changing time interval T D (k) is T DS , k, and Δt, which corresponds to the following equation (1).

number

[0034] Then, the transmission processing unit 60 calculates the transmission start time T S Set (k).

number

[0035] The transmission processing unit 60 calculates the time interval T corresponding to the above formula for each of the specified number of chirp signals in one transmission cycle. D (k) and transmission start time T S In addition, the transmission processing unit 60 specifies a monotonically changing center frequency as a parameter that specifies each chirp signal in one transmission cycle.

[0036] The transmission processing unit 60 detects the center frequency F of the kth chirp signal. S For (k), time interval T D(k) is set to a frequency such that the product of k and k is substantially linear with respect to time and the number of orders of the chirp signal in a specific time domain. D This means that the relative change rate of the time change rate, which is the relative change rate with respect to the reference interval of (k), with respect to the frequency change rate, which is the relative change rate with respect to the reference frequency of the center frequency, falls within the allowable change rate range. Hereinafter, 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. Hereinafter, the allowable change rate range is a range in which the ratio change rate is equal to or less than a specified upper threshold value and equal to or more than a specified lower threshold value. Furthermore, the specific time range is a time range in which the ratio change rate is equal to or less than a specified upper limit time and equal to or more than a specified lower limit time. For example, the specific time range is a time range after a specified time has passed since the start of the transmission cycle, i.e., a time range in which the upper limit time is the specified time and the lower limit time is zero.

[0037] Here, the time change rate A and the frequency change rate B of the k-th chirp signal correspond to the values ​​calculated by the following formulas (3) and (4). Note that the reference interval for the time change rate A is the first time interval T DS , the reference frequency at frequency change rate B is the first center frequency F SS Let us assume that.

number

number

[0038] Therefore, the ratio change rate corresponds to the value obtained by dividing the right side of the formula (3) by the right side of the formula (4). The transmission processing unit 60 selects a center frequency F at which the ratio change rate falls within the allowable change rate range in a specific time domain. S (k). For example, the time interval T D Assume that (k) is the change mode represented by the graph in FIG. 5. In this case, the transmission processing unit 60 changes the center frequency F S (k) is varied for each chirp signal in such a way that the ratio change rate becomes the change pattern shown in the graph of FIG.S (k) is the time interval T D (k) and the transmission start time T S This corresponds to the parameter expressed by the following formula (5), which is a value at which the product with (k) is substantially linear.

number

[0039] Here, the direction of change in the ratio change rate from the succeeding chirp signal side to the preceding chirp signal side in each transmission cycle is only one negative direction. That is, the graph of the ratio change rate in one transmission cycle is only one of the inversely proportional hyperbolic curves as shown in Fig. 7. For this reason, the transmission processing unit 60 manages the number of each chirp signal in one transmission cycle so that it starts from k=1.

[0040] The IC constituting the control unit 6 is generally capable of adjusting the time interval in units of about 10 ns. Also, the IC is generally capable of adjusting the center frequency in units of tenths of a second.

[0041] In addition, the transmission processing unit 60 in the first embodiment generates a transmission signal in which the time interval for each chirp signal changes linearly with respect to time and the number of sequences of the chirp signal, and the center frequency changes monotonically. In other words, it can be understood that the transmission processing unit 60 generates a transmission signal in which the time interval for each signal set of a single chirp signal changes linearly and the center frequency changes monotonically. In addition, the time width from the start to the end of the transmission of the chirp signal in the transmission cycle and the size of the bandwidth are set to be substantially the same, for example. In addition, the transmission end time of the preceding chirp signal and the transmission start time of the following chirp signal are set to be substantially the same.

[0042] Next, in S20, the transmission processing unit 60 receives the transmission signal reflected by the target as a received signal. In the following S30, the reception processing unit 61 obtains a beat signal corresponding to the received signal.

[0043] Then, in S40, the reception processing unit 61 performs frequency analysis on the beat signal to obtain target information on the target. The target information includes at least the distance and relative speed of the target to the radar device 1. Specifically, the reception processing unit 61 executes two FFT (Fast Fourier Transform) processes on the beat signal. As a result, the transmission processing unit 60 obtains a two-dimensional spectrum related to the distance and relative speed.

[0044] More specifically, the transmission processor 60 first performs FFT processing on the beat signal for each chirp. This first FFT processing obtains, for each chirp, a frequency spectrum (distance spectrum) showing a peak at the frequency position corresponding to the distance to the target. The distance spectrum is data showing the signal strength for each distance bin according to the distance resolution.

[0045] When the relative speed with respect to the target is not zero, the distance spectrum corresponding to each chirp shows a peak in the same distance bin, but the phases are different between the chirps. This phase difference between the chirps is caused by the change in the distance between the radar device 1 and the target. Using this, the FCM (Fast Chirp Modulation) method detects the relative speed with respect to the target. By performing these two FFT processes, the transmission processing unit 60 acquires a two-dimensional spectrum for the distance and the relative speed.

[0046] Specifically, as the second FFT process, the reception processor 61 performs FFT processing on a waveform in which the phases at the distance bins obtained in the first FFT process for multiple chirps are arranged in time series. This allows a frequency spectrum (speed spectrum) showing a peak at a position corresponding to the relative speed with respect to the target to be obtained for each speed bin. Depending on the maximum detectable speed, speed 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 can be obtained by the second FFT process.IF (k) corresponds to the following equation, where r is the target's distance, v is its speed, and c is its light speed. ch is a parameter that is determined according to the slope of the chirp signal, and is +1 if the slope is positive and -1 if the slope is negative.

number

[0048] Here, the central frequency F S (k) and time interval T D The product with (k) is substantially linear. S (k) is the time interval T until the kth chirp signal D (k), the transmission start time T S (k) and center frequency F S The product with (k) is also linear. That is, the center frequency F 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, it is easier to suppress the broadening of the peak even if the target velocity increases.

[0049] The reception processing unit 61 acquires the distance and relative speed of the target as target information based on the result of the second FFT process. In the next step S50, the reception processing unit 61 outputs the acquired target information. The output process of the target information includes a process of transmitting the target information to an external device, a process of storing the target information in a storage medium, and the like.

[0050] The direction of the detection target can be detected based on the irradiation direction of the beam. If the receiver 12 has a plurality of 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 detection target information to a driving control ECU (Electronic Control Unit) that controls the driving 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 the allowable change rate range in a specific time domain. Therefore, it is possible to prevent the product of the time interval and the center frequency of the chirp signal from becoming nonlinear in the specific time domain. Since the center frequency can be adjusted more finely than the time interval, the ratio change rate can be more easily brought within the allowable change rate range by adjusting the center frequency, and the constraints on parameters other than the center frequency can be relaxed. As a result, it is possible to suppress the broadening of the peak and relax the constraints on the chirp signal.

[0052] Second Embodiment As shown in FIG. 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 in accordance with the transmission cycle. In other words, the transmission processing unit 60 changes the positive and negative slopes of the frequency change over time of each chirp signal in accordance with the transmission cycle. For example, as shown in FIG. 8, the transmission processing unit 60 sets the slope of the frequency change to a positive direction in a specific transmission cycle, and switches the slope of the frequency change to a 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 in accordance with the transmission cycle, so that interference with other radar devices 1 can be suppressed.

[0055] Third embodiment As shown in FIG. 9, the third embodiment is a modification 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 according to the transmission cycle. In other words, the transmission processing unit 60 changes the positive and negative slope of the center frequency change over time in one entire transmission cycle according to the transmission cycle. For example, as shown in FIG. 9, the transmission processing unit 60 sets the slope of the center frequency change to a positive direction in a specific transmission cycle, and switches the slope of the center frequency change to a negative direction in the immediately following transmission cycle.

[0057] According to the third embodiment described above, the central frequency of each chirp signal switches between increasing and decreasing over time in accordance with the transmission cycle, so that interference with other radar devices 1 can be suppressed.

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

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

[0060] Fifth embodiment As shown in FIG. 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 the center frequency of the chirp signals in a transmission cycle to change for each set of multiple chirp signals. In the example shown in Fig. 11, the transmission processing unit 60 sets the time interval and the center frequency to change for each set of two consecutive chirp signals.

[0062] According to the fifth embodiment described above, the center frequency and the time interval are changed for each set of chirp signals, not for each chirp signal. This allows for smaller time interval adjustment compared to changing for each chirp signal. For example, if the minimum value of the time interval that can be set by the control unit 6 is 10 ns, adjustment at 5 ns can be achieved by changing it once every two times. If there is a difference between the required time interval and the implementable time interval, changing the time interval for each set of multiple chirp signals as described above allows for finer time interval control.

[0063] (Other embodiments) Although several embodiments have been described above, the present disclosure should not be construed as being limited to those embodiments, and can be applied to various embodiments and combinations within the scope not departing from the gist of the present disclosure.

[0064] In a variant, the time interval T D (k) may be an interval between representative times in the chirp signal other than the transmission start time. The representative times other than the transmission start time may be, for example, the transmission end time of the chirp signal, the frequency of the chirp signal having a center frequency F S (k) is the time, etc.

[0065] In a modified example, the rate of change of the ratio from the trailing chirp signal side to the leading chirp signal side in each transmission cycle may vary in only one direction, the positive direction.

[0066] In a variant, the time interval T of the chirp signal D (k) and center frequency F SParameters other than (k) may be changed as appropriate. Furthermore, the preceding chirp signal and the following chirp signal may be separated in time, or may partially overlap in time.

[0067] In a 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 a chirp signal to be transmitted from each of the multiple transmitting antennas TX.

[0068] In a 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 a chirp signal to be transmitted from each of the multiple transmitting antennas TX.

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

[0070] In addition to the above-described embodiments and modifications, the above-described embodiments and modifications may be implemented as a control device that is configured to be mountable on a host mobile object and has 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 multiple technical ideas described in the following multiple dependent claims. Some of the claims may be described in a multiple dependent form, where the subsequent claim alternatively refers to the preceding claim. Furthermore, some of the claims may be described in a multiple dependent form, where the subsequent claim alternatively refers to the preceding claim. The claims described in these multiple dependent forms define multiple technical ideas.

[0072] (Technical thought 1) A radar device having a processor (6b), the radar device transmitting a plurality of signal sets each including at least one chirp signal whose frequency varies over time in each transmission cycle, the signal sets comprising: The processor, transmitting the sets of signals, the center frequency of the chirp signal varying monotonically for each set of signals, and the time intervals between the sets of signals varying linearly in time; Obtaining reception data of a reflected signal of the chirp signal reflected by a target in the outside world; configured to run Transmitting the set of signals comprises: a frequency change rate is a relative change rate of the center frequency for each of the signal sets with respect to a reference frequency, and a time change rate is a relative change rate of the time interval for each of the signal sets with respect to a reference interval, adjusting the center frequency so that a ratio change rate, which is a relative change rate of the time change rate to the frequency change rate, falls within an allowable change rate range in a specific time domain.

[0073] (Technical thought 2) A radar device according to technical idea 1, in which the direction of change in the ratio change rate from the succeeding signal set to the preceding signal set in each transmission cycle is only one of a positive direction and a negative direction.

[0074] (Technical Thought 3) The radar device according to Technical Idea 1 or Technical Idea 2, in which the signal set is transmitted by switching between increasing and decreasing the frequency of the chirp signal over time according to the transmission cycle.

[0075] (Technical Thought 4) A radar device described in any one of Technical Ideas 1 to 3, in which the signal set is transmitted by switching between an increase and a decrease in the center frequency of each signal set over time according to the transmission cycle.

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

[0077] (Technical Thought 6) The 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 of the signal sets.

[0078] The above technical idea may be embodied in the form of a radar control method and a radar control program. [Explanation of symbols]

[0079] 1: radar device, 6a: memory (storage medium), 6b: processor

Claims

1. A radar device having a processor (6b) for transmitting a plurality of signal sets each including at least one chirp signal whose frequency varies over time, in each transmission cycle, the radar device comprising: The processor, transmitting the sets of signals, the center frequency of the chirp signal varying monotonically for each set of signals, and the time intervals between the sets of signals varying linearly in time; Obtaining reception data of a reflected signal of the chirp signal reflected by a target in the outside world; configured to run Transmitting the set of signals comprises: a frequency change rate is a relative change rate of the center frequency for each of the signal sets with respect to a reference frequency, and a time change rate is a relative change rate of the time interval for each of the signal sets with respect to a reference interval, adjusting the center frequency so that a ratio change rate, which is a relative change rate of the time change rate to the frequency change rate, falls within an allowable change rate range in a specific time domain.

2. 2. The radar device according to claim 1, wherein the signal set has a rate of change in the ratio from the succeeding signal set to the preceding signal set in each transmission cycle in only one of a positive direction and a negative direction.

3. The radar device according to claim 1 , wherein transmitting the set of signals switches between increasing and decreasing the frequency of the chirp signal over time in accordance with the transmission cycle.

4. The radar device according to claim 1 , wherein transmitting the set of signals switches between increasing and decreasing the center frequency of each of the signal sets over time in accordance with the transmission cycle.

5. The radar system of claim 1 , wherein transmitting the set of signals comprises transmitting a single chirp signal for each of the set of signals.

6. The radar system of claim 1 , wherein transmitting the set of signals comprises transmitting a plurality of chirp signals for each of the set of signals.

7. A radar control method executed by a processor (6b) for controlling a radar device (1) that transmits a set of signals each transmission cycle, the set including at least one chirp signal whose frequency varies over time, the method comprising: transmitting the sets of signals, the center frequency of the chirp signal varying monotonically for each set of signals, and the time intervals between the sets of signals varying linearly in time; Obtaining reception data of a reflected signal of the chirp signal reflected by a target in the outside world; Including, Transmitting the set of signals comprises: a frequency change rate is a relative change rate of the center frequency for each of the signal sets with respect to a reference frequency, and a time change rate is a relative change rate of the time interval for each of the signal sets with respect to a reference interval, adjusting the center frequency so that a ratio change rate, which is a relative change rate of the time change rate to the frequency change rate, falls within an allowable change rate range in a specific time domain.

8. A radar control program for controlling a radar device (1) that transmits a plurality of signal sets each including at least one chirp signal whose frequency varies over time in each transmission cycle, the program being stored in a storage medium (6a) and including instructions to be executed by a processor (6b), the program comprising: The instruction: transmitting the signal sets such that the center frequency of the chirp signal varies monotonically for each of the signal sets and the time intervals between the signal sets vary linearly over time; Acquiring reception data of a reflected signal of the chirp signal reflected by a target in the outside world; Including, Causing the set of signals to be transmitted includes: a frequency change rate is a relative change rate of the center frequency for each of the signal sets with respect to a reference frequency, and a time change rate is a relative change rate of the time interval for each of the signal sets with respect to a reference interval, adjusting the center frequency so that a ratio change rate, which is a relative change rate of the time change rate to the frequency change rate, falls within an allowable change rate range in a specific time region.

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