Speed detection device, information processing device, and speed detection method

Abstract

A speed detection device according to one embodiment of the present technology comprises: a plurality of transmission antennas; a plurality of reception antennas; a chirp control unit; and a speed detection unit. The plurality of transmission antennas transmit a plurality of chirp signals. The plurality of reception antennas receive the plurality of chirp signals reflected by an object. The chirp control unit controls the plurality of chirp signals so that the chirp signals are simultaneously transmitted from the plurality of transmission antennas, while changing the combination of phases of the plurality of chirp signals for each of a plurality of time slots. The speed detection unit detects the speed of the object on the basis of the signals from the plurality of reception antennas. The chirp control unit sets, to different intervals, at least two intervals of time slots in which the combination of the phases of the plurality of chirp signals become the same.

Description

Speed detection device, information processing device, and speed detection method

[0001] The present technology relates to a speed detection device, an information processing device, and a speed detection method applicable to the detection of the speed of an object.

[0002] Multiple-input multiple-output (MIMO) radar is known as a device capable of, for example, excellent speed detection with angle estimation ability. However, due to the large number of antennas, the speed detection range may become narrow. For example, Patent Document 1 describes a speed detection device that performs speed expansion in a MIMO antenna. In this device, the intervals between the chirps transmitted from a plurality of transmitting antennas are set to be unequal intervals. As a result, the phase folding range corresponding to the speed is expanded, and it becomes possible to widen the speed detection range.

[0003] Japanese Unexamined Patent Application Publication No. 2023-70351

[0004] Generally, as a method of MIMO antennas, a time division multiplexing (TDM) method in which chirps are transmitted sequentially from a plurality of transmitting antennas, and a binary phase multiplexing (BPM) method in which the phases of the chirps are changed for each of the plurality of transmitting antennas and transmitted simultaneously from each transmitting antenna are known. Among these, the BPM method can improve the sensitivity as a radar compared to the TDM method.

[0005] On the other hand, in the BPM method, there is a possibility that a signal necessary for speed expansion cannot be obtained depending on the way of transmitting the chirps due to interference between the simultaneously irradiated chirps or the like. Therefore, there is a need for a technology that can improve the sensitivity and widen the speed detection range.

[0006] In view of the above circumstances, an object of the present technology is to provide a speed detection device, an information processing device, and a speed detection method capable of improving the sensitivity and widening the speed detection range.

[0007] To achieve the above objective, a velocity detection device according to one embodiment of this technology comprises a plurality of transmitting antennas, a plurality of receiving antennas, a chirp control unit, and a velocity detection unit. The plurality of transmitting antennas transmit a plurality of chirp signals. The plurality of receiving antennas receive the plurality of chirp signals reflected by an object. The chirp control unit controls the plurality of chirp signals so that each chirp signal is transmitted simultaneously from the plurality of transmitting antennas, while changing the combination of phases of the plurality of chirp signals for each of the plurality of time slots. The velocity detection unit detects the velocity of the object based on the signals from the plurality of receiving antennas. The chirp control unit sets at least two of the time slot intervals in which the combination of phases of the plurality of chirp signals is the same to different intervals.

[0008] In this speed detection device, multiple chirp signals are transmitted simultaneously from multiple transmitting antennas, with varying phase combinations for each of the multiple chirp signals within each time slot. Furthermore, at least two of the phase combinations of the multiple chirp signals within the same time slot interval are set to be different. This improves sensitivity and expands the speed detection range.

[0009] The chirp control unit may set a repeating period in which multiple time slots are arranged so that the combination of phases of the multiple chirp signals is the same.

[0010] The chirp control unit may sequentially set a plurality of different interval values ​​as the interval between time slots in which the combination of phases of the plurality of chirp signals is the same in the repeating period.

[0011] The plurality of time slots may include a plurality of individual slots, each having a different phase combination of the plurality of chirp signals, and the number of these slots may be the same as the plurality of transmitting antennas.

[0012] The chirp control unit may configure multiple slot sets, each containing the multiple individual slots, such that the order of the multiple individual slots differs in each slot set.

[0013] The chirp control unit may configure at least three or more slot sets.

[0014] The speed detection unit may generate a plurality of first received signals corresponding to the plurality of individual slots based on signals from the plurality of receiving antennas, while assuming a plurality of speed aliasing values ​​due to phase aliasing, and generate a plurality of second received signals corresponding to the plurality of transmitting antennas by combining the plurality of first received signals using a decoding formula corresponding to the combination of phases of the plurality of chirp signals.

[0015] The speed detection unit may add the plurality of second received signals and determine the speed aliasing value when the amplitude of the sum is maximum as the true speed aliasing value.

[0016] The speed detection unit may perform a Fourier transform on the plurality of second received signals and determine that the speed aliasing value when the peak of the Fourier transform is at its maximum is the true speed aliasing value.

[0017] The interval between the time slots at which the combinations of phases of the plurality of chirp signals are the same may be an integer multiple of the time width of the chirp signal.

[0018] The interval between the time slots at which the phase combinations of the plurality of chirp signals are the same may be a non-integer multiple of the time width of the chirp signal.

[0019] The chirp control unit may set the phase of the chirp signal using the BPM (Binary Phase Multiplexing) method.

[0020] An information processing device according to one embodiment of this technology includes a chirp control unit and a velocity detection unit. The chirp control unit controls the multiple chirp signals transmitted from the multiple transmitting antennas so that each chirp signal is transmitted simultaneously from the multiple transmitting antennas, while changing the combination of phases of the multiple chirp signals transmitted from the multiple transmitting antennas for each of the multiple time slots. The velocity detection unit detects the velocity of an object based on signals from the multiple receiving antennas that receive the multiple chirp signals reflected by the object. The chirp control unit sets at least two of the time slot intervals in which the combination of phases of the multiple chirp signals is the same to different intervals.

[0021] A velocity detection method according to one embodiment of the present technology includes the following steps: controlling a plurality of chirp signals so that each chirp signal is transmitted simultaneously from a plurality of transmitting antennas, while changing the combination of phases of the plurality of chirp signals transmitted from the plurality of transmitting antennas for each of a plurality of time slots; detecting the velocity of an object based on signals from a plurality of receiving antennas that receive the plurality of chirp signals reflected by the object; the step of controlling the plurality of chirp signals includes setting at least two of the intervals of the time slots in which the combination of phases of the plurality of chirp signals is the same to different intervals.

[0022] This is a block diagram showing an example configuration of a speed detection device according to the first embodiment of this technology. This is a schematic diagram showing an example of antenna arrangement in a MIMO radar. This is a schematic diagram illustrating speed detection using a single transmitting antenna. This is a schematic diagram showing a transmission time chart for multiple transmitting antennas. This is a schematic diagram illustrating speed aliasing. This is a schematic diagram illustrating the transmission timing of unevenly spaced chirp signals. This is a graph showing the period of the phase ratio of chirp signals Tx1 and Tx2 obtained when chirp signals are transmitted at equal intervals from transmitting antennas TX1 and TX2. This is a graph showing the period of the phase ratio of chirp signals Tx1 and Tx2 obtained when chirp signals are transmitted at uneven intervals from transmitting antennas TX1 and TX2. This is a schematic diagram showing an example of a TDM-MIMO transmission time chart. This is a schematic diagram showing an example of a BPM-MIMO transmission time chart. This is a schematic diagram showing another example of a transmission time chart in the TDM method. This is a schematic diagram showing another example of a transmission time chart in the BPM method. This is a graph showing the radiation characteristics in Slot 1. This is a graph showing the radiation characteristics in Slot 2. This is a graph showing the response signals of each slot in the BPM method. This is a schematic diagram showing an example of a chirp signal transmission time chart according to this embodiment. This is a schematic diagram explaining the order of each slot shown in Figure 16. This is a schematic diagram explaining distance detection using a chirp signal. This is a schematic diagram explaining speed detection using a chirp signal. This is a schematic diagram explaining angle detection using a chirp signal. This is a schematic diagram showing the structure image of received data. This is a schematic diagram explaining distance FFT processing. This is a schematic diagram explaining Doppler FFT processing. This is a schematic diagram showing an example of the processing result of distance Doppler FFT. This is a schematic diagram explaining angle FFT processing. This is a table showing an example of a transmission time chart according to this embodiment. This is a flowchart showing an example of the speed aliasing value determination process. This is a schematic diagram showing an example of the structure of received data used in the determination process. This is a schematic diagram explaining the phase vector obtained for each slot set. This is a graph showing the relationship between the integrated amplitude and the speed aliasing value. This is a table showing the transmission timing and interval of the individual slots shown in Figure 26. This is a graph showing the relationship between the speed phase and the speed aliasing value in each slot.This graph shows the relationship between the amplitude of the signal obtained by combining the velocity phases of each slot and the velocity aliasing value. This graph shows an example of the calculation result of the judgment process. This is a block diagram showing an example of the configuration of a vehicle control system. This is a diagram showing an example of a sensing area.

[0023] The embodiments of this technology will be described below with reference to the drawings.

[0024] [Configuration of the Speed ​​Detection Device] Figure 1 is a block diagram showing an example configuration of a speed detection device according to the first embodiment of this technology. The speed detection device 100 is a device that detects the speed of an external object 2 by emitting radio waves to the object 2 and detecting the reflected waves from the object 2. More specifically, the speed detection device 100 detects the relative speed between the speed detection device 100 and the object 2.

[0025] Typically, the speed detection device 100 is a radar device that detects the speed of object 2, as well as the distance to object 2 and the direction in which object 2 is located. The speed detection device 100 is configured as an on-board radar, for example, mounted on an automobile. However, the type and application of the speed detection device 100 are not limited, and it may be configured as a radar mounted on a portable device or a stationary device, for example.

[0026] The speed detection device 100 includes an antenna unit 110 and an information processing device 120. The antenna unit 110 has a plurality of transmitting antennas TX and a plurality of receiving antennas RX. The plurality of transmitting antennas TX transmit a plurality of chirp signals Tx. In other words, the transmitting antennas can be said to irradiate the object 2 with chirp signals Tx. The plurality of receiving antennas RX receive the plurality of chirp signals Tx reflected by the object 2. Hereinafter, the chirp signals Tx reflected by the object 2 may be referred to as reflected chirp signals rTx.

[0027] In the speed detection device 100, a MIMO radar is formed by multiple transmitting antennas TX and multiple receiving antennas RX. The MIMO radar is a radar in which the aperture length (i.e., the receiving area of ​​the antennas) is virtually increased by arranging, for example, multiple transmitting antennas TX spatially offset from multiple receiving antennas RX. The arrangement of each antenna will be described later with reference to Figure 2, etc.

[0028] The information processing device 120 controls the operation of each part of the speed detection device 100 and performs processing for detecting the speed of object 2. As shown in Figure 1, the information processing device 120 has a chirp control unit 121, a beat signal generation unit 122, and a signal processing unit 123.

[0029] The chirp control unit 121 controls the transmission of chirp signals Tx by multiple transmitting antennas TX. The chirp control unit 121 has multiple chirp generation units 124, each provided for each of the multiple transmitting antennas TX. Each chirp generation unit 124 generates the chirp signal Tx to be transmitted by the corresponding transmitting antenna TX.

[0030] Furthermore, the chirp control unit 121 controls the phase and transmission timing of the chirp signal Tx. Specifically, the chirp control unit 121 controls multiple chirp signals Tx so that each chirp signal Tx is transmitted simultaneously from multiple transmitting antennas TX, while changing the combination of phases of multiple chirp signals Tx for each of multiple time slots. Thus, the speed detection device 100 becomes a radar device that uses a simultaneous transmission method.

[0031] In this embodiment, the chirp control unit 121 sets the phase of the chirp signal Tx using the BPM method. Specifically, the phases of multiple chirp signals Tx are set to either 0 or π. By using the BPM method, it becomes possible to easily realize a desired phase pattern using, for example, a phase shifter. Furthermore, decoding processing becomes easier, and the computational load can be reduced. The transmission patterns (transmission time charts, etc.) of each chirp signal Tx will be described later with reference to Figure 16, etc.

[0032] The beat signal generation unit 122 amplifies the reflected chirp signal rTX received by the multiple receiving antennas RX and generates a beat signal based on the chirp signal Tx and the reflected chirp signal rTx. The beat signal includes the signal component of the chirp signal Tx and the signal component of the reflected chirp signal rTx.

[0033] The signal processing unit 123 includes a beat signal processing unit 125, a decoding processing unit 126, an amplitude detection unit 127, and an aliasing determination unit 128. The beat signal processing unit 125 reads the beat signal generated by the beat signal generation unit 122 and generates a received signal (first received signal) corresponding to each time slot based on the beat signal. The decoding processing unit 126 decodes the first received signal and generates a received signal (second received signal) corresponding to each transmitting antenna TX. The amplitude detection unit 127 calculates the amplitude of the second received signal for each transmitting antenna TX. The aliasing determination unit 128 uses the amplitude data of the second received signal to determine the number of velocity aliasing events caused by phase aliasing and calculates the true velocity based on the determination result.

[0034] In this manner, the velocity detection device 100 detects the velocity of object 2 based on signals from multiple receiving antennas RX, using a beat signal generation unit 122 and a signal processing unit 123 located downstream of the multiple receiving antennas RX. In this embodiment, the velocity detection unit is comprised of the beat signal generation unit 122 and the signal processing unit 123. The operation of each part of the signal processing unit 123 will be explained in detail later.

[0035] [MIMO Radar] Figure 2 is a schematic diagram showing an example of antenna arrangement in a MIMO radar. In a MIMO radar, the number of receiving antennas RX can be virtually increased by arranging multiple transmitting antennas TX, for example. The upper part of Figures 2A and 2B schematically illustrates an actual arrangement example of a MIMO radar, while the lower part schematically illustrates an arrangement example of a virtually configurable receiving antenna RX.

[0036] Figure 2A shows an example of a horizontal MIMO configuration. Here, eight receiving antennas RX1 to RX8 are arranged horizontally in the figure, and two transmitting antennas TX1 and TX2 are positioned offset horizontally from each receiving antenna RX in the same horizontal direction. In this case, RX1 to RX8 are expanded horizontally, forming a receiving antenna array with 8 x 2 = 16 virtual receiving antennas arranged in a single row. This improves, for example, the horizontal resolution.

[0037] Figure 2B shows an example of a vertical MIMO configuration. Here, eight receiving antennas RX1 to RX8 are arranged horizontally in the figure, and three transmitting antennas TX1 to TX3 are arranged vertically, offset from the arrangement direction of each receiving antenna RX. In this case, RX1 to RX8 are extended vertically, forming a receiving antenna array with 8 x 3 = 24 virtual receiving antennas arranged in a grid. This improves the resolution in the vertical direction in addition to the horizontal direction.

[0038] Figure 3 is a schematic diagram illustrating velocity detection using a single transmitting antenna. Figure 3 schematically shows multiple chirp signals Tx (Txa, Txb, Txc, and Txd) transmitted from a single transmitting antenna TX, and multiple reflected chirp signals rTx (rTxa, rTxb, rTxc, and rTxd) received by the receiving antenna RX after each chirp signal Tx is reflected by object 2. In the figures for Tx and rTx, the horizontal direction represents time, and the vertical direction represents frequency. Here, it is assumed that object 2 is moving at a constant velocity V.

[0039] The chirp signal Tx transmitted from the transmitting antenna Tx is a signal whose frequency changes over time, and typically a signal whose frequency increases linearly with time is used. Here, the chirp signal Tx is transmitted repeatedly at a chirp interval Tc. The chirp interval Tc corresponds to the time width (irradiation time) of the chirp signal Tx.

[0040] Here, since object 2, which reflects the chirp signal Tx, is moving at a constant velocity V, the Doppler effect causes a phase shift in the reflected chirp signal rTx compared to the original chirp signal Tx. The phase differences between the chirp signals Txa, Txb, Txc, and Txd and the reflected chirp signals rTxa, rTxb, rTxc, and rTxd are φ0, φ0+φd, φ0+2×φd, and φ0+3×φd, respectively.

[0041] Thus, the phase differences between the chirp signals Txa to Txd and the reflected chirp signals rTxa to rTxd each include different phase change amounts φd, and the phase change amount φd changes with the passage of time. The phase change amount φd is proportional to the displacement amount Tc × V of the object 2. Assuming the wavelength of the chirp signal Tx is λ, φd and V satisfy the following relationship. φd = (4π × Tc × V) / λ ··· (1) V = (φd × λ) / (4π × Tc) ··· (2)

[0042] Here, the phase change amount φd will be folded back within the range of ±π according to the sampling theorem. Therefore, when transmitting the chirp signal Tx from one transmitting antenna TX at the chirp interval Tc, the maximum detection speeds Vmax in both the positive and negative directions are expressed as follows. Vmax = ±λ / (4 × Tc) ··· (3)

[0043] FIG. 4 is a schematic diagram showing a transmission time chart for a plurality of transmitting antennas. Here, it is assumed that the chirp signals Tx1 and Tx2 are transmitted from two transmitting antennas TX1 and TX2 in a time-division manner.

[0044] In the example shown in FIG. 4, the transmission timings of each chirp signal Tx are set at equal intervals with respect to the burst interval TB. Here, the burst interval TB is the interval between a plurality of chirp signals Tx of the same antennas when separating the chirp signals Tx multiplexed among a plurality of transmitting antennas TX for each transmitting antenna TX. That is, it can also be said that the burst interval TB is the repetition period of the entire transmission time chart.

[0045] Here, the chirp signals Tx1 and Tx2 are transmitted alternately. Therefore, the interval between a plurality of chirp signals Tx of the same transmitting antennas TX becomes the burst interval TB. Also, assuming the number of transmitting antennas TX is N, it is set as TB = N × Tc.

[0046] Even when a plurality of transmission antennas TX are provided, the speed detection of the object 2 is performed using the chirp signal Tx transmitted from the same transmission antenna TX. For this reason, in the example shown in FIG. 4, the burst interval TB becomes the period of the chirp signal Tx. In this case, the maximum detection speed Vmax is expressed as follows. Vmax = ±λ / (4 × N × Tc) ··· (4)

[0047] Comparing equation (4) with equation (3), it can be seen that as the number N of transmission antennas TX increases, the maximum detection speed Vmax decreases. Therefore, in a MIMO radar, the maximum detection speed decreases by the number of transmission antennas TX.

[0048] [Speed Expansion] FIG. 5 is a schematic diagram for explaining speed folding. For example, the phenomenon that the speed (relative speed) of the object 2 exceeds the above-described maximum detection speed Vmax and the original speed cannot be detected is called speed folding. Speed folding occurs because the phase difference (phase fluctuation amount φd) between the chirp signals to be compared folds within the range of ±π.

[0049] For example, assume that the maximum detection speed Vmax is ±20 km / h. Here, +20 km / h corresponds to a phase of +π, and -20 km / h corresponds to a phase of -π. Also, assume that the speed of the object 2 is +40 km / h (in terms of phase, +2π). In this case, the speed of the object 2 is detected as 0 km / h from the radar due to speed folding.

[0050] Here, when the speed folding value Nwrap is introduced, the speed Vexp of the object 2 with expanded speed is expressed as follows. Vexp = Vmeas + 2 × Nwrap × Vmax ··· (5)

[0051] The velocity aliasing value Nwrap is an integer including 0 (Nwrap = 0, ±1, ±2, ...). Vmeas is the velocity detection value within the range of ±Vmax. For example, a speed of +40 km / h corresponds to a velocity aliasing value Nwrap = 1 within the radar's velocity detection range. Therefore, in the example shown in Figure 5, if it can be determined that the velocity aliasing value Nwrap is 1, the true velocity can be detected from equation (3). Velocity extension is a technique for correctly detecting the velocity aliasing value Nwrap without error.

[0052] Figure 6 is a schematic diagram illustrating the transmission timing of unequally spaced chirp signals. Here, as in Figure 4, chirp signals Tx1 and Tx2 are transmitted in time division from two transmitting antennas TX1 and TX2, respectively, but the transmission timing intervals of chirp signals Tx1 and Tx2 are different from each other.

[0053] Here, the transmission timing of chirp signal Tx1 is set to 0, and the transmission timing of chirp signal Tx2 is set to k. The timing corresponding to the burst interval TB (the timing at which the next chirp signal Tx1 is transmitted) is denoted as l. In this case, the phase φ2 corresponding to the extended speed detected by chirp signal Tx2 (the phase difference between adjacent reflected chirp signals rTx2) is expressed as follows using the relationship in equation (5): φ2 = (Vmeas + 2 × Nwrap × Vmax) × (k / l) × TB ... (6)

[0054] Here, Vmax is the velocity at which the phase is π in the burst interval TB, satisfying the relationship Vmax × Tb = π. Rewriting equation (6) from this relationship, the phase φ2 can be expressed as follows: φ2 = Vmeas × (k / l) × TB + 2π × Nwrap × (k / l) ... (7)

[0055] In equation (7), +2π × Nwrap × (k / l) is the 2π folding term for Nwrap with phase φ2. Therefore, folding occurs at a period in which Nwrap × (k / l) is an integer. If the transmission timings of chirp signals Tx1 and Tx2 are equally spaced, as shown in Figure 4, then k / l = 1 / 2. In this case, Nwrap × (1 / 2) is an integer when Nwrap is a multiple of 2. Therefore, the number of foldings allowed in speed folding is limited to 2. That is, |Nwrap| ≤ 2.

[0056] In contrast, as shown in Figure 6, when the transmission timing intervals of chirp signals Tx1 and Tx2 are different, the period in which Nwrap × (k / l) is an integer is longer than when the transmission timings are equally spaced. For example, if Tc = 40 μs and k = 70 μs, then TB = l = 110 μs. In this case, aliasing occurs at a period in which Nwrap × (70 / 110) = Nwrap × (7 / 11) is an integer. That is, aliasing occurs when Nwrap is a multiple of 11. Therefore, the number of aliasing events allowed in speed aliasing is extended to 11. In other words, |Nwrap| ≤ 11.

[0057] Figure 7 is a graph showing the period of the phase ratio of chirp signals Tx1 and Tx2 obtained when chirp signals are transmitted at equal intervals from transmitting antennas TX1 and TX2. The horizontal axis of the graph is the velocity aliasing value Nwrap, and the vertical axis is the phase ratio normalized by 2π for the phase φ2 in equation (6). In Figure 7, Tc = 40 μs, k = 40 μs, and TB = l = 80 μs. In this case, looking in the positive direction, different phases (velocities) are obtained for each velocity aliasing value Nwrap only up to Nwrap = 0 and 1. Therefore, as shown by the thick black line, the allowable number of velocity aliasing values ​​Nwrap is 2.

[0058] Figure 8 is a graph showing the period of the phase ratio of chirp signals Tx1 and Tx2 obtained when chirp signals are transmitted at unequal intervals from transmitting antennas TX1 and TX2. In Figure 8, as in the numerical example above, Tc = 40 μs, k = 70 μs, and TB = l = 110 μs. In this case, looking in the positive direction, different phases (velocities) are obtained for each velocity aliasing value Nwrap in the range of Nwrap = 0 to 11. Therefore, as shown by the thick line in the black frame, the allowable number of velocity aliasing values ​​Nwrap is 11.

[0059] Thus, when transmitting multiple chirp signals Tx from multiple transmitting antennas TX, the number of allowable speed aliasing values ​​Nwrap can be extended by making the intervals between each chirp signal Tx unequal. Although equation (6) above was explained in relation to φ2, a similar explanation can be given for the phase φ1 corresponding to the expanded speed of the chirp signal Tx1, using φ2 as a reference.

[0060] [TDM and BPM Methods] Figure 9 is a schematic diagram showing an example of a TDM-MIMO transmission time chart. In TDM-MIMO, multiple transmitting antennas TX (here, transmitting antennas TX1 to TX8) that constitute the MIMO transmit chirp signals Tx (here, chirp signals Tx1 to Tx8) in a time-division manner. That is, each transmitting antenna TX1 to TX8 transmits chirp signals Tx1 to Tx8 in a predetermined order. Also, different transmitting antennas TX do not transmit chirp signals Tx simultaneously. Figures 4 and 6 above are transmission time charts for TDM-MIMO when there are two transmitting antennas TX.

[0061] In the example shown in Figure 9, chirp signals Tx1 to Tx8 are transmitted repeatedly in this order. The transmission intervals of chirp signals Tx1 to Tx8 (the interval between transmissions of two consecutive signals) are equal and are set to, for example, the chirp interval Tc. Chirp signals Tx1 to Tx8 are all set to the same phase. In this way, in the TDM method, the chirp signals Tx are separated by time, so the chirp signals Tx can be classified directly from the received signal.

[0062] Figure 10 is a schematic diagram showing an example of a BPM-MIMO transmission time chart. In BPM-MIMO, chirp signals Tx (here, chirp signals Tx1 to Tx8) are simultaneously transmitted from multiple transmitting antennas TX (here, transmitting antennas TX1 to TX8) that constitute the MIMO, with the phase changing to 0 or π for each of the multiple time slots 5. The combinations of phases of chirp signals Tx1 to Tx8 in each time slot 5 (hereinafter also referred to as phase patterns) are set to be different from each other.

[0063] Here, time slot 5 refers to the time domain that includes, for example, the simultaneously transmitted chirp signals Tx1 to Tx8. The width of time slot 5 is typically the chirp interval Tc. Phase "0" is approximately the same as the reference phase (for example, the phase of the first chirp signal Tx1 transmitted at time 0), and phase "π" is a phase shifted by π (180°) from the reference phase.

[0064] In the example shown in Figure 9, eight time slots 5 (Slot 1 to Slot 8), the same number as the number of transmitting antennas TX, are set as multiple time slots, and these Slots 1 to Slot 8 are transmitted repeatedly in this order. Each of Slots 1 to Slot 8 has a different phase pattern. In other words, Slots 1 to Slot 8 can be identified by their phase pattern. Also, in the BPM method, each chirp signal Tx cannot be classified by time, so the received signal is classified by multiple time slots 5 (Slot 1 to Slot 8).

[0065] Furthermore, in the BPM method, the chirp signals Tx1 to Tx8 can be separated (decoded) using the signals obtained in Slot1 to Slot8 and a decoding formula corresponding to the set phase pattern. For example, Tx2 can be separated using the following decoding formula: Tx2 = Slot1 - Slot2 + Slot3 - Slot4 + Slot5 - Slot6 + Slot7 - Slot8 ... (8) Here, Tx2 and Slot1 to Slot8 in equation (8) represent received signals (received data), such as the processing result of distance Doppler FFT.

[0066] BPM-MIMO transmits chirp signals Tx (Tx1-Tx8) simultaneously from all transmitting antennas TX (TX1-TX8), significantly improving the signal-to-noise ratio (SNR). For example, with eight transmitting antennas TX, chirp signals Tx are transmitted from all transmitting antennas TX in eight time slots 5, resulting in a total of 8 x 8 = 64 chirp progression Tx. This is eight times the value of TDM-MIMO shown in Figure 9. Thus, using BPM-MIMO improves the SNR and enhances the radar's sensitivity.

[0067] Figure 11 is a schematic diagram showing another example of a transmission time chart in the TDM method. Figure 11 shows an example where the transmission timing intervals of chirp signals Tx1 to Tx8 for multiple transmitting antennas TX1 to TX8 are set to unequal intervals. Here, as in Figure 9, chirp signals Tx1 to Tx8 are transmitted in this order, but the intervals between them are set to be partially unequal. For example, the transmission timings for Tx1, Tx2, Tx3, Tx4, Tx5, Tx6, Tx7, and Tx8 are set to 0, Tc, 2Tc, 3.5Tc, 4.8Tc, 6.6Tc, 7.7Tc, and 9.2Tc, respectively. The transmission timing (burst interval TB) for the next Tx1 is set to 11Tc.

[0068] In this way, by making the transmission intervals of chirp signals Tx1 to Tx8 unequal, the phase corresponding to each Tx will have a small shift relative to TB, and the period of the phase relative to the velocity aliasing value Nwrap will increase. As a result, the number of times the velocity aliasing value Nwrap can be allowed will increase, and the velocity detection range can be expanded.

[0069] Furthermore, depending on the arrangement of the transmitting antennas TX and the application of the radar, it may also be possible to detect phase differences between different transmitting antennas TX (between chirp signals Tx obtained within the burst interval TB). For example, in configurations such as 2D-MIMO, where multiple transmitting antennas TX are grouped together and spaced apart, it may be necessary to correct the phase of the data from one group to the data from another group. In such cases, it is possible to achieve speed expansion by changing the order in which the chirp signals Tx are transmitted and altering the transmission timing between the antennas whose phase difference is to be detected.

[0070] Figure 12 is a schematic diagram showing another example of a transmission time chart in the BPM method. In Figure 12, some of the transmission timings for multiple time slots 5 (Slot 1 to Slot 8) are set at unequal intervals. For example, the transmission timings for Slot 1, Slot 2, Slot 3, Slot 4, Slot 5, Slot 6, Slot 7, and Slot 8 are set to 0, Tc, 2Tc, 3.5Tc, 4.8Tc, 6.6Tc, 7.7Tc, and 9.2Tc, respectively, as in Figure 11. For example, by setting them in this way, it is thought that speed expansion becomes possible when determining the phase of the signals obtained in Slot 1 to Slot 8. On the other hand, in the BPM method, as will be explained below, there may be slots where no gain can be obtained, and it is conceivable that it may be difficult to apply the method shown in Figure 12 as is.

[0071] [Radiation Characteristics in the BPM Method] Figure 13 is a graph showing the radiation characteristics in Slot 1. Figure 14 is a graph showing the radiation characteristics in Slot 2. The left side of Figures 14 and 13 schematically illustrates the antenna array including transmitting antennas TX1 to TX8 and the set phase, while the right side shows a graph illustrating the simulation results of the antenna array's directivity. The horizontal axis of the graph is the azimuth angle (Azimuth [deg]), and the vertical axis is the directivity of the antenna array expressed using gain (Dielectricity [dB]). Here, the same phase pattern as in Figures 10 and 12 is used.

[0072] In the BPM method, each chirp signal Tx1 to Tx8 is transmitted simultaneously with its phase changed, so the directivity (the direction in which the greatest gain is obtained) of the transmitting antennas TX1 to TX8 differs for each time slot 5 depending on the combination of phases. For example, as shown in Figure 13, Slot 1, in which the phases of all chirp signals Tx1 to Tx8 are set to 0, will have gain in the forward direction. On the other hand, as shown in Figure 14, Slot 2, in which the phases of chirp signals Tx1 to Tx8 are alternately set to 0 and π, will have no gain in the forward direction.

[0073] Therefore, for example, in the forward direction, Slot 1 can transmit a signal with sufficient strength, but Slot 2 cannot transmit a signal with sufficient strength. Also, if the same phase pattern as in Figures 10 and 12 is used, Slots 3 to 8 will not be able to obtain sufficient gain in the forward direction, just like Slot 2. In other words, when using the phase patterns shown in Figures 10 and 12, only Slot 1 among Slots 1 to 8 will have gain in the forward direction.

[0074] Figure 15 is a graph showing the response signals for each slot in the BPM system. Here, the results of the distance FFT obtained by transmitting the chirp signal Tx in Slots 1 to 8 when there is a target object 2 in the front direction are shown. The horizontal axis represents the FFT bins corresponding to distance, and the vertical axis represents the FFT intensity.

[0075] For example, in Slot 1, each chirp signal Tx can be sent to object 2 in the forward direction, so a peak is obtained at a position corresponding to the distance to object 2. On the other hand, no peaks are obtained in the other Slots 2 to 8. In other words, object 2 in the forward direction can only be detected in Slot 1 and cannot be detected in the other Slots 2 to 8.

[0076] For example, in the TDM method, chirp signals Tx1 to Tx8 are transmitted in time division, so such directional bias due to phase interference does not occur. In addition, chirp signals Tx1 to Tx2 are separated according to their respective transmission timings and used, for example, for detecting the velocity of object 2.

[0077] In this regard, for example, even in the BPM system, if the corresponding chirp signal Tx can be separated from each time slot 5, such as the chirp signal Tx1 transmitted in Slot 1 and the chirp signal Tx2 transmitted in Slot 2, then it is thought that signals corresponding to the chirp signals Tx1 to Tx8 transmitted in time division multiplexing used in the TDM system can be obtained.

[0078] However, as mentioned above, in the BPM method, Slots 2 to 8 other than Slot 1 do not have gain in the forward direction. Therefore, even if unequal spacing is performed as shown in Figure 12, for example, effective results cannot be obtained from processes such as detecting the phase difference between Slot 1 and the other Slots 2 to 8. Furthermore, as mentioned above, it is difficult to properly separate the corresponding chirp signal Tx from each time slot 5.

[0079] Therefore, the inventors investigated a method for achieving sufficient speed expansion without affecting the directivity of such a BPM system.

[0080] [Overview of Speed ​​Detection Device] Figure 16 is a schematic diagram showing an example of a transmission time chart for a chirp signal according to this embodiment. Figure 17 is a schematic diagram illustrating the order of each slot shown in Figure 16. Figures 16 and 17 schematically illustrate the arrangement pattern of time slots 5 used in the speed detection device 100 (transmission time chart 130). In the transmission time chart 130, the time width of the time slot 5 is set to, for example, the time width of the chirp signal Tx (chirp interval Tc).

[0081] In the speed detection device 100, the chirp control unit 121 shown in Figure 1 sets at least two of the intervals of time slots 5 in which the phase combinations of multiple chirp signals Tx are the same to different intervals. Here, the time slots 5 in which the phase combinations of multiple chirp signals Tx are the same refer to the time slots 5 in which the phase patterns of each chirp signal Tx transmitted simultaneously are common. Hereafter, time slots 5 in which the phase combinations of multiple chirp signals Tx are the same will be referred to as individual slots 6. The transmission time chart 130 includes multiple such individual slots 6 (three in this case).

[0082] The interval between time slots 5 (interval between individual slots 6) where the phase combinations of multiple chirp signals Tx are the same is, for example, the transmission timing interval of individual slots 6 of the same type. In the transmission time chart, individual slots 6 of the same type are transmitted at two or more different intervals. That is, the intervals between individual slots 6 are set to unequal intervals. This makes it possible to achieve sufficient speed expansion in processes such as detecting phase differences between individual slots 6 of the same type.

[0083] In this embodiment, the chirp control unit 121 sets a repeating period in which multiple time slots 5 (individual slots 6) are arranged so that the combination of phases of multiple chirp signals Tx is the same. The repeating period is the period of the transmission pattern of the time slots 5. Figures 16 and 17 show a transmission time chart 130 for one period, and the period in which this transmission time chart 130 is executed (for example, the time width of the transmission time chart 130) becomes the repeating period.

[0084] As described above, the transmission time chart 130 includes multiple individual slots 6 of the same type at different intervals. In other words, the transmission time chart 130 can be described as a transmission pattern in which the repeating unit of individual slots 6 is extended to include multiple individual slots 6. The repetition period corresponds to the burst interval TB described above. Hereafter, the repetition period may be referred to as the burst interval TB'.

[0085] As shown in Figure 16, the multiple time slots 5 each contain multiple individual slots 6, the same number as the multiple transmitting antennas TX, with each individual slot having a different phase combination of multiple chirp signals Tx. In other words, there are the same number of individual slots 6 of different types as there are multiple transmitting antennas TX.

[0086] Here, as in Figure 10, eight transmitting antennas TX1 to TX8 are provided. Therefore, the transmission time chart 130 is set with eight individual slots Slot1 to Slot8, each containing eight chirp signals Tx1 to Tx8. In addition, each individual slot 6 in the transmission time chart 130 is transmitted three times. Therefore, the transmission time chart 130 is set with 8 x 3 = 24 time slots 5. These 24 slots represent the smallest unit of speed expansion signal processing.

[0087] Furthermore, the multiple individual slots Slot1 to Slot8 are arranged in 24 slots such that slots of the same type are spaced unevenly apart. In the following, the index representing the first individual slot 6 will be "a", the index representing the second individual slot 6 will be "b", and the index representing the third individual slot 6 will be "c". That is, Slot1a to Slot8a are the first individual slot 6, Slot1b to Slot8b are the second individual slot 6, and Slot1c to Slot8c are the third individual slot 6.

[0088] In this embodiment, multiple slot sets 7, each containing multiple individual slots 6, are configured such that the order of the multiple individual slots 6 differs in each slot set 7. Here, three slot sets 7a to 7c, each containing eight individual slots 6, are configured, and the transmission time chart 130 is constructed by arranging the three slot sets 7. The indices (a, b, c) indicating the above-mentioned order directly represent the indices of the slot sets 7a to 7c. By constructing the transmission time chart 130 using the slot sets 7, it becomes possible to perform calculation processing on a unit basis of the slot sets 7, for example, reducing processing time.

[0089] Furthermore, in each slot set 7, the order of the eight individual slots 6 set within it is different from one another. This makes it easy to arrange each individual slot 6 such that at least two of the spacings between individual slots 6 of the same type are different.

[0090] Furthermore, by setting three slot sets 7, it becomes possible to set at least two different intervals for individual slots 6 of the same type. This makes it possible to generate phases rotating with two different periods as phase differences for individual slots 6 of the same type (see Figure 32, etc.). This significantly expands the oscillation period of the phase difference with respect to the velocity reflection value Nwrap, for example, and makes it possible to sufficiently increase the allowable number of velocity reflection values ​​Nwrap. As a result, it becomes possible to sufficiently expand the velocity detection range. It is preferable that the number of slot sets 7 be set to have at least two or more different intervals. That is, it is sufficient to have at least three or more slot sets 7.

[0091] Here, we will explain an example of setting the intervals for each individual slot 6 with reference to Figure 17. In Figure 17, 24 time slots are set with slot numbers i = 0 to 23. For each individual slot 6, the interval between the first and second times is denoted as Δ1, and the interval between the second and third times is denoted as Δ2. Here, slot number i is used to represent Δ1 and Δ2.

[0092] For example, Slot1a, Slot1b, and Slot1c are located at i=0, 11, and 16 respectively, with Δ1 being 11 and Δ2 being 5. Similarly, Slot2a, Slot2b, and Slot2c are located at i=7, 12, and 23, with Δ1 being 5 and Δ2 being 10. Furthermore, Slot3a, Slot3b, and Slot3c are located at i=1, 10, and 22, with Δ1 being 9 and Δ2 being 12. Thus, each individual slot 6 has different intervals Δ1 between the first and second rounds, and different intervals Δ2 between the second and third rounds. Note that individual slots 6 of different types may include some with the same intervals.

[0093] Thus, in this embodiment, during the repetition period (burst interval TB'), multiple different interval values ​​(Δ1 and Δ2) are sequentially set as the intervals between time slots 5 (individual slots 6) in which the combination of phases of multiple chirp signals Tx is the same. This makes it possible to arrange each individual slot 6 at unequal intervals within the radar measurement processing unit, and makes it easy to achieve sufficient speed expansion.

[0094] Note that there may be spaces between multiple individual slots. The spaces between slots may be provided between all individual slots 6, or only between some of them. In this case, the interval values ​​(Δ1 and Δ2) of the individual slots 6 are set as time including the space.

[0095] As explained with reference to Figures 13 to 15, in the BPM method, Slots 2 to 8, other than Slot 1, do not have gain in the forward direction. Therefore, for example, if there is an object 2 in the forward direction, it is necessary to detect the velocity of object 2 by comparing it with a signal containing information from, for example, Slot 1.

[0096] As an alternative method, for example, one could simply repeat a transmission pattern as shown in Figure 12 and compare the data obtained at each timing. In this case, for example, the phase of Tx1 detected by decoding the signals from eight slots (Slot1 to Slot8) will change with the transmission period (burst interval TB) of the slot set including Slot1 to Slot8. That is, the decoded Tx1 is equivalent to a signal transmitted at equal intervals with a burst interval TB for eight slots. For this reason, the velocity aliasing value Nwrap is limited by the burst interval TB, and the allowable number of Nwraps will not be very large.

[0097] In contrast, in this embodiment, each individual slot 6 is arranged at unequal intervals. As a result, the phase corresponding to each individual slot 6 has a small shift with respect to the overall burst interval TB', and the period of the phase with respect to the velocity reflection value Nwrap becomes larger. As a result, the allowable number of velocity reflection values ​​Nwrap increases, and it becomes possible to widen the velocity detection range when detecting the velocity (phase difference) of the object 2 from each individual slot 6.

[0098] This makes it possible to detect the velocity (phase difference) obtained from Slot 1s within a wide velocity detection range, even in situations where, for example, only Slot 1 has gain in the forward direction. As a result, it becomes possible to properly detect the velocity of object 2 even when object 2 is present in the forward direction. Thus, by using this technology, it is possible to achieve sufficient velocity expansion without being affected by the directivity that arises depending on the phase pattern. In addition, since each chirp signal Tx is transmitted simultaneously, the signal-to-noise ratio is improved, enabling highly sensitive radar measurements.

[0099] [Generating Received Data] The following describes the process for generating received data used in determining the speed aliasing value. The process for generating received data is performed, for example, by the beat signal processing unit 125 shown in Figure 1. Here, we will explain using the case of transmitting a single chirp signal Tx as an example. In reality, multiple chirp signals Tx will be transmitted simultaneously (slots will be transmitted), but the process described below is also applicable when multiple chirp signals Tx are involved.

[0100] Figure 18 is a schematic diagram illustrating distance detection using a chirp signal. As shown in the upper part of Figure 18, when a chirp signal Tx is transmitted, if the chirp signal Tx is reflected by an object, a reflected chirp signal rTx is received, delayed by T = r × 2 / c (where r is the distance and c is the luminous flux). Also, as shown in the lower part of Figure 18, when the phase-shifted chirp signal Tx and the reflected chirp signal rTx are mixed, a beat signal IF is obtained. By performing an FFT (Fast Fourier Transform) on the sampled data within one chirp of the beat signal IF and converting it to frequency, the frequency difference ΔF between the chirp signal Tx and the reflected chirp signal rTx is obtained. Since the delay time T can be determined from this frequency difference ΔF, the distance r can be detected.

[0101] Figure 19 is a schematic diagram illustrating velocity detection using chirp signals. As shown in the upper part of Figure 19, when object 2 is moving relative to another object, the phase difference between multiple chirp signals Tx and reflected chirp signal rTx changes over time due to the Doppler effect. For example, as shown in the lower part of Figure 19, a phase change corresponding to the velocity can be observed in the first and second reflected chirp signals rTx. By observing such phase changes between multiple chirps, the velocity can be detected. However, the velocity that can be detected at this time is limited by the maximum detection velocity Vmax explained in equations (3) and (4) (e.g., ±40 km / h). Therefore, to detect a velocity greater than this, it is necessary to perform velocity expansion processing.

[0102] Figure 20 is a schematic diagram illustrating angle detection using chirp signals. For example, the distance to object 2 differs for each of the multiple receiving antennas RX (here, RX1 and RX2). Therefore, the angle relative to object 2 can be determined by detecting the phase difference of the reflected chirp signals rTx detected between each receiving antenna RX. For example, the path difference Δr between RX1 and RX2 is expressed as Δr = d × sinθ, where d is the antenna spacing. Δr is calculated from the phase difference of the reflected chirp signals rTx, and from there the angle θ (direction, etc.) relative to object 2 can be calculated.

[0103] Figure 21 is a schematic diagram showing the structure of received data. Figure 21 shows an image of the received data 140 obtained by each FFT process described below. The received data 140 has a data structure with, for example, three dimensions. The first dimension (D1) corresponds to the sampling data of a single chirp and becomes a dimension representing distance according to frequency by performing a distance FFT (Range-FFT). The second dimension (D1) corresponds to the same distance data for multiple chirps and becomes a dimension representing velocity according to frequency by performing a Doppler FFT (Doppler-FFT). The third dimension (D3) corresponds to the same distance and velocity data for multiple receiving antennas RX and becomes a dimension representing angle according to frequency by performing an angle FFT (Angle-FFT). The process for obtaining data for each dimension will be explained in order.

[0104] Figure 22 is a schematic diagram illustrating distance FFT processing. In distance FFT, an FFT is performed on all data recorded in memory (Range Doppler Data Buffer) in the direction of the first dimension (the direction of Range in Figure 22). For example, an FFT is performed on the data in the uppermost row, and then on the data in the rows below it.

[0105] Figure 23 is a schematic diagram illustrating the Doppler FFT process. In Doppler FFT, an FFT is performed on all data recorded in memory (Range Doppler Data Buffer) in the direction of the second dimension (the direction of Doppler in Figure 23). For example, the FFT is performed on the leftmost column of data, and then on the column to its right.

[0106] Note that the Range Doppler Data Buffer data blocks shown in Figures 22 and 23 consist of Ntx × Nrx data blocks, where Ntx is the number of transmitting antennas TX (or the number of Slots) and Nrx is the number of receiving antennas RX. The processing shown in Figures 22 and 23 (Distance Doppler FFT) is performed on these data blocks.

[0107] Figure 24 is a schematic diagram showing an example of the processing result of distance Doppler FFT. The data after distance Doppler FFT becomes sparse data in which peaks 141 exist only in a specific Range (first dimension) and Doppler (second dimension). By detecting these peaks 141, the distance and velocity of object 2 in the radar's detection direction can be detected. Note that the velocity at this point is a provisional velocity that does not take aliasing into account, so velocity expansion processing will be performed on each of these peaks 141 afterward.

[0108] Figure 25 is a schematic diagram illustrating the angle FFT processing. In angle FFT, the FFT is performed on the processing data of the distance Doppler FFT specified by the transmitting antenna TX (or Slot) and the receiving antenna RX. For example, the angle is detected by integrating the data obtained by extracting the peak of the distance Doppler FFT for each data point of the same distance and velocity, and then applying the FFT. In this embodiment, since the processing data of the distance Doppler FFT is mainly used, the angle FFT does not necessarily have to be performed.

[0109] Furthermore, the specific methods used for distance FFT, Doppler FFT, and angle FFT are not limited; for example, any method used in radar measurements can be applied.

[0110] [Determination Process for Speed ​​Allocation Value] Figure 26 is a table showing an example of a transmission time chart according to this embodiment. The table in Figure 26 shows, from top to bottom, the slot name, the start time (transmission timing) of each slot, the transmission order of individual slots 6, and the phase pattern of each individual slot 6. Slot name "1a" corresponds to Slot 1a shown in Figures 16 and 17, and the same applies to other slot names. The start time is the transmission time when the chirp interval Tc = 1. Here, the transmission time of Slot 1a, which is transmitted first, is set to 0. In the transmission order column, the transmission order is indicated by marking the ones to be transmitted at each time from each Slot 1 to Slot 8 with an asterisk "*". The phase pattern column shows eight binary patterns consisting of combinations of 0 or π set for each individual slot 6.

[0111] Here, a decimal value is set as the start time. For example, in the second slot set 7b, the start times for Slot 7b, Slot 5b, and Slot 3b are set to 8.1, 9.1, and 10.1. Also, the start time for Slot 1b is set to 11.3, and the start times for subsequent slots increase by 1 until the start time for Slot 7c in slot set 7c. The start times for the remaining Slots 5c, 3c, and 2c are set to 21.6, 22.6, and 23.6. The burst interval TB' is set to 25.4.

[0112] This setting allows the interval between individual slots 6 of the same type to be a non-integer multiple of the chirp interval Tc. That is, the interval between time slots 5 (individual slots 6) where the phase combination of multiple chirp signals Tx is the same is a non-integer multiple of the time width Tc of the chirp signal Tx. This makes it possible to shift the phase difference between individual slots 6 of the same type by a small fractional range. As a result, compared to the case where it is set to an integer multiple, for example, the aliasing term that occurs when assuming a velocity aliasing value Nwrap is less likely to be a multiple of 2π. This makes it possible to significantly increase the number of times the velocity aliasing value Nwrap can be tolerated.

[0113] Furthermore, the spacing between individual slots 6 is not limited to the examples described above, and may be set to an integer multiple of the time width Tc of the chirp signal Tx. For example, the transmission time chart 130 shown in Figures 16 and 17 is an example where the spacing is set to an integer multiple. This makes it possible to arrange the individual slots 6 without gaps, for example, and thus shorten the burst interval TB' (repetition period). In addition, the method of setting the spacing between individual slots 6 is not limited, and the spacing between each individual slot 6 may be set appropriately so that individual slots 6 of the same type are spaced unevenly within the burst interval TB'.

[0114] In the speed return value determination process described below, the transmission time chart 130 shown in Figure 26 shall be used.

[0115] Figure 27 is a flowchart showing an example of the process for determining the velocity aliasing value. Figure 28 is a schematic diagram showing an example of the structure of the received data used in the determination process. First, the received data will be explained with reference to Figure 28.

[0116] The received data 140 is data generated using the distance Doppler FFT described with reference to Figures 22 to 24. Here, as shown in Figure 26, multiple types of individual slots 6 are transmitted, so a signal corresponding to each individual slot 6 (reflected slot signal) is obtained. Distance Doppler FFT is then performed on the sampled data obtained in this way.

[0117] In Doppler FFT, for example, the data from 24 slots transmitted the first time is compared with the data from 24 slots transmitted the second time. At this time, Doppler FFT is performed on the data in the same slot. That is, the data from Slot 1a in the first transmission is compared with the data from Slot 1a in the second transmission. Similarly, the data from Slot 1b in the first transmission is compared with the data from Slot 1b in the second transmission.

[0118] Through the process described above, as shown in Figure 28, for each peak 141 (target object 2), a distance Doppler signal (complex value) equal to the number of transmitting antennas RX Nrx is generated for each slot (in this case, 24 slots) included in the transmission time chart 130. These complex values ​​are used as received data 140 to perform the process of determining the velocity aliasing value Nwrap.

[0119] Next, with reference to Figure 27, the process for determining the velocity aliasing value Nwrap will be explained. Before this process is performed, the distance Doppler FFT and the like described above are executed, and the received data 140 shown in Figure 28 is generated. Once the received data 140 is generated, the process for determining the velocity aliasing value Nwrap is executed for the target peak 141. In other words, the process shown in Figure 27 is, for example, the process for determining the velocity aliasing value Nwrap for each peak 141.

[0120] First, the velocity wrapping value Nwrap is set to its minimum value (step 101). For example, the search range for the velocity wrapping value Nwrap is set to Nwrap ≤ ±Ns. Ns is a setting value that defines the range in which the judgment process is performed, and is set to be less than or equal to the allowable number of velocity wrapping values ​​Nwrap. By performing the velocity extension described above, it is possible to extend the effective range of Ns. Here, Nwrap is set to -Ns.

[0121] Next, the velocity phase is corrected assuming a velocity aliasing value Nwrap (step 102). The velocity phase is the phase of the distance Doppler signal contained in the received data 140, and represents the velocity before correction. This process is performed, for example, by the decoding processing unit 126 shown in Figure 1, and is performed for each of the 24 data slots as shown below.

[0122] For slot set 7a, each velocity phase is corrected as follows.

[0123] Here, the parameters of equations (9.1)-(9.8) are explained, with the individual slot number 6 being "*" (* = 1, 2, ... 8). Slot*a_vc is the signal after velocity phase correction. Slot*a is the signal before velocity phase correction, and is the distance Doppler value obtained as the received data 140 described above. Both Slot*a_vc and Slot*a are complex values ​​and exist in quantities equal to the number of receiving antennas RX. Slot*aOntime is the transmission start timing of Slot*a (start time in Figure 26). BurstTime is the repetition interval of the 24 slots (burst interval TB'). dopplerbin is the velocity bin after Doppler FFT. dopplerfftnum is the number of calculations for Doppler FFT. Nwrap is the assumed velocity aliasing number (velocity aliasing value Nwrap set in each loop).

[0124] Similarly, for slot set 7b, each velocity phase is corrected as follows.

[0125] Furthermore, for slot set 7c, each velocity phase is corrected as follows.

[0126] In this manner, the decoding processing unit 126 generates multiple speed phase correction slot signals corresponding to multiple individual slots 6 based on signals from multiple receiving antennas RX, while assuming multiple speed aliasing values ​​Nwrap due to phase aliasing. In this embodiment, the speed phase correction slot signals Slot*a_vc, Slot*b_vc, and Slot*c_vc correspond to the first received signal.

[0127] Next, the decoding processing unit 126 separates multiple chirp signals Tx from all slots (step 103). Specifically, using a decoding formula corresponding to the phase pattern set in the multiple individual slots 6, each chirp signal Tx1 to Tx8 is separated for each slot set 7a to 7c.

[0128] For slot set 7a, the chirp signals Tx1a_vc to Tx8a_vc after speed phase correction are calculated as follows.

[0129] Furthermore, for slot set 7b, the chirp signals Tx1b_vc to Tx8b_vc after speed phase correction are calculated as follows.

[0130] Furthermore, for slot set 7c, the chirp signals Tx1c_vc to Tx8c_vc after speed phase correction are calculated as follows.

[0131] In this manner, the decoding processing unit 126 synthesizes multiple speed phase correction signals (slot signals after speed phase correction) according to a decoding formula corresponding to the combination of phases of multiple chirp signals Tx1 to Tx8, thereby generating multiple speed phase correction chirp signals corresponding to multiple transmitting antennas TX. These speed phase correction chirp signals are signals separated for each transmitting antenna TX, and their phases have already been corrected according to the speed aliasing value Nwrap. In this embodiment, the speed phase correction chirp signals Tx*a_vc, Tx*b_vc, and Tx*c_vc correspond to the second received signals.

[0132] Furthermore, the speed phase correction chirp signals (Tx*a_vc, Tx*b_vc, Tx*c_vc) for each of the seven decoded slot sets are added together in a complex number state. This is done to preserve the phase information that has been shifted by unequal spacing. Specifically, multiple chirp signals Tx1 to Tx8, each representing the speed phase, are calculated as follows. Note that all of the multiple chirp signals Tx1 to Tx8 are complex values, and the same number of each are calculated as the number of receiving antennas RX.

[0133] Figure 29 is a schematic diagram illustrating the phase vector obtained for each slot set. As described above, the velocity phase of the received chirp signal is a value corresponding to the velocity of object 2. Therefore, when the correct velocity aliasing value Nwrap is set in equations (9.1) to (9.8), (10.1) to (10.8), and (11.1) to (11.8), the chirp signal Tx transmitted from the same transmitting antenna TX will be a signal with the same velocity phase.

[0134] For example, as shown on the left side of Figure 29, if the assumed Nwrap matches the true Nwrap, Tx*a_vc, Tx*b_vc, and Tx*c_vc are combined in phase, and the amplitude of Tx* is maximized. Conversely, as shown on the right side of Figure 29, if the assumed Nwrap differs from the true Nwrap, Tx*a_vc, Tx*b_vc, and Tx*c_vc are combined in different phases, and the amplitude is reduced. In this embodiment, the true Nwrap is determined by focusing on this characteristic. The specific processing will be described below.

[0135] Returning to Figure 27, the amplitude of the chirp signal Tx* representing the velocity phase is calculated for all transmitting antennas RX (step 104). This process is performed by the amplitude detection unit 127 shown in Figure 1. Since the chirp signal Tx* is calculated for multiple receiving antennas RX (for example, eight receiving antennas RX1 to RX8), the amplitudes of all of them are calculated.

[0136] Specifically, for each of the chirp signals Tx* calculated by equations (15.1) to (15.8), the amplitude is calculated as follows.

[0137] Here, amp() is a function that calculates the amplitude (real value) as a complex number. Also, ampTx* is the value of the distance Doppler amplitude calculated for each transmitting antenna RX.

[0138] Next, the amplitude ampTx* of the chirp signal Tx* representing the velocity phase is added for all transmitting antennas RX (step 104). For example, the amplitude detection unit 127 adds the amplitudes of Tx* calculated for each transmitting antenna RX as shown in the following equation.

[0139] Here, Sum(t,d) is a function that integrates the signal t in a specific dimension in direction d. Therefore, Sum(ampTx*,Rxdim) means integrating the amplitude ampTx* of Tx* in the direction of RX. Also, ampTx*Rxsum is a single real value (the combined amplitude of Tx*) obtained by integrating the amplitudes of Tx* that exist for each transmitting antenna RX.

[0140] Furthermore, once ampTx*Rxsum is calculated, the amplitude detection unit 127 adds each ampTx*Rxsum. Specifically, the results of equations (17.1) to (17.8) are added together as follows.

[0141] The ampTxsumRxsum shown in equation (18) is the sum of the integrated amplitudes obtained by each transmitting antenna RX that receives multiple chirp signals Tx, and is a single real value.

[0142] Figure 30 is a graph showing the relationship between the integrated amplitude and the velocity aliasing value. Figure 30 shows an example of the results of calculating ampTxsumRxsum while changing the velocity aliasing hypothesis (Nwarp) in the process described so far. The horizontal axis of the graph is Nwarp, and the vertical axis shows the value of ampTxsumRxsum in [dB]. Here, the correct velocity aliasing value is 0, and it can be seen in the graph that ampTxsumRxsum is maximized when Nwarp = 0.

[0143] The value of the velocity aliasing hypothesis that maximizes this amplitude is determined as the true velocity aliasing value Nwarp. This process is performed in step 109 after calculating ampTxsumRxsum for all Nwarps.

[0144] Returning to Figure 27, the value of Nwrap and the value of the added amplitude (ampTxsumRxsum) are recorded (step 106), and 1 is added to Nwrap (step 107). Next, it is determined whether Nwrap has reached its maximum value (step 108). For example, it is determined whether Nwrap is greater than Ns. For example, if Nwrap ≤ Ns (No in step 108), the processes in steps 102 to 108 are executed again. If Nwrap > Ns (Yes in step 108), the reversal determination unit 128 shown in Figure 1 performs a determination process to determine the true Nwrap (step 109).

[0145] In step 109, as shown in Figure 30, the maximum value of ampTxsumRxsum is detected from the data showing the relationship between Nwrap and ampTxsumRxsum obtained up to step 108. The value of the velocity reflection value Nwrap that takes this maximum value is determined to be the true velocity reflection value Nwrap. Once the true velocity reflection value Nwrap is determined, the true velocity of object 2 is calculated from equation (5) using that value.

[0146] In this embodiment, multiple velocity phase correction chirp signals (Tx*a_vc, Tx*b_vc, Tx*c_vc) are added together, and the velocity aliasing value Nwrap at which the amplitude of the sum is maximized is determined as the true velocity aliasing value Nwrap. This makes it possible to determine the true velocity aliasing value Nwrap through a relatively simple calculation.

[0147] Figure 31 is a table showing the transmission timing and intervals for the individual slots shown in Figure 26. Figure 32 is a graph showing the relationship between the velocity phase and velocity aliasing value in each slot. Figure 33 is a graph showing the relationship between the amplitude of the signal obtained by combining the velocity phases of each slot and the velocity aliasing value.

[0148] Figure 32 plots the velocity phase (foldback velocity phase) of each individual slot Slot1 to Slot8 in the first to third slot sets 7a to 7b against the velocity foldback value Nwrap. Here, 1st, 2nd, and 3rd are the values ​​for individual slot 6 in slot sets 7a, 7b, and 7c, respectively. For example, for Slot1, the phase of the value calculated by equations (9.1), (10.1), and (11.1) above is plotted. Note that each phase is normalized by the phase of 1st.

[0149] As shown in the graph of Slot 1 in Figure 32, the graphs for 2nd and 3rd have different periods. In this regard, as shown in Figure 31, in the transmission time chart 130, the interval Δ1 between the 1st and 2nd transmissions for Slot 1 is 11.3, and the interval Δ2 between the 2nd and 3rd transmissions is 5. Therefore, looking at Slot 1 as a whole, a signal is obtained that is a combination of a phase that rotates with a period of 11.3 and a phase that rotates with a period of 5.

[0150] By transmitting Slot 1 at two or more different intervals in this way, the phase shift becomes complex, creating a situation where the periodic term relative to Nwarp is less likely to be an integer multiple of 2π. Similarly, for Slots 2 to 8, signals with two types of phases combined are obtained, making it less likely for the periodic term to be an integer multiple of 2π. This makes it possible to sufficiently increase the velocity aliasing value Nwarp, and significantly expand the velocity detection range.

[0151] Figure 33 plots the amplitude of the combined distance Doppler result obtained from the 1st, 2nd, and 3rd slots (slot phase combined amplitude) against the velocity aliasing value Nwarp. Specifically, it plots ampTx* calculated from equation (16.1) to (16.8). In this case, the amplitude is largest at the velocity aliasing value Nwarp where the phases of the 1st, 2nd, and 3rd slots match (i.e., the true velocity aliasing value Nwarp). This is because Nwarp = 0 is the true velocity aliasing value. In all slots, the maximum value is at Nwarp = 1.

[0152] Figure 34 is a graph showing an example of the calculation results of the judgment process. Figure 34 plots the integrated values ​​of the slot phase synthesis amplitudes of Slot 1 to Slot 8 against the velocity aliasing value Nwrap. Looking at the integrated values, a clear peak appears at the true velocity aliasing value Nwrap = 1. In this way, by using the integrated values, it is possible to improve the accuracy of the velocity aliasing value judgment process.

[0153] In the speed detection device 100 according to this embodiment, for each of the multiple time slots 5, multiple chirp signals Tx are simultaneously radiated from multiple transmitting antennas TX while changing the combination of phases of the multiple chirp signals Tx. Furthermore, at least two of the intervals between the same time slots 5 (individual slots 6) have different phase combinations of the multiple chirp signals. This makes it possible to improve sensitivity and broaden the speed detection range.

[0154] <Other Embodiments> This technology is not limited to the embodiments described above, and various other embodiments can be realized.

[0155] In the above embodiment, a method was described for determining the true velocity aliasing value Nwrap from the amplitude of the sum of multiple velocity phase correction chirp signals (Tx*a_vc, Tx*b_vc, Tx*c_vc). Other methods may be used to determine the true velocity aliasing value Wrap.

[0156] For example, it is also possible to perform a Fourier transform on the velocity phase-corrected chirp signal (second received signal) and determine the velocity aliasing value Nwrap at the point where the peak of the Fourier transform is maximum as the true velocity aliasing value Nwrap.

[0157] Specifically, the frequency spectrum of the velocity phase can be obtained by performing a Fourier transform (FFT) in the RX and TX directions on the corrected velocity phases Tx*a_vc, Tx*b_vc, and Tx*c_vc calculated for each of the multiple receiving antennas RX. By searching for a velocity aliasing value Nwrap such that the peaks of the frequency spectrum match for each of Tx*a_vc, Tx*b_vc, and Tx*c_vc, it is possible to obtain the true velocity aliasing value Nwrap. This allows for the exploration of the phase in the frequency domain, enabling accurate determination of the velocity aliasing value Nwrap.

[0158] The above describes a method for rearranging the order of individual slots within a slot set in a transmission time chart. However, it is not limited to this method; for example, the order may be changed across slot sets. For instance, a transmission pattern in which Slot 1 is placed twice within the first eight slots may be used.

[0159] Furthermore, while the above embodiment described an example in which three individual slots are arranged within the repeating period TB', four or five individual slots may also be arranged. Alternatively, two individual slots may be arranged. In this case, the interval between the first individual slot and the second individual slot is set to be different from the interval between the second individual slot and the first individual slot included in the next period. In this way, multiple individual slots can be arranged within the repeating period TB', and the number is not particularly limited.

[0160] In the above embodiment, the BPM method was described as a method for setting the phase. This technology can also be applied to other methods that perform simultaneous transmission by modulating (encoding) the phase, in addition to the BPM method.

[0161] Figure 35 is a block diagram showing an example configuration of a vehicle control system 11, which is an example of a mobile device control system to which this technology is applied.

[0162] The vehicle control system 11 is installed in the vehicle 1 and performs processing related to the automation of the vehicle's operation. This automation includes Level 1 to Level 5 automation, as well as remote operation and remote assistance of the vehicle 1 by a remote driver.

[0163] The vehicle control system 11 includes a vehicle control ECU (Electronic Control Unit) 21, a communication unit 22, a map information storage unit 23, a location information acquisition unit 24, an external recognition sensor 25, an in-vehicle sensor 26, a vehicle sensor 27, a memory unit 28, an automated driving control unit 29, a DMS (Driver Monitoring System) 30, an HMI (Human Machine Interface) 31, and a vehicle control unit 32.

[0164] The vehicle control ECU 21, communication unit 22, map information storage unit 23, location information acquisition unit 24, external recognition sensor 25, in-vehicle sensor 26, vehicle sensor 27, memory unit 28, driving automation control unit 29, DMS 30, HMI 31, and vehicle control unit 32 are connected to each other so as to be able to communicate with one another via a communication network 41. The communication network 41 is composed of an in-vehicle communication network or bus that conforms to digital bidirectional communication standards such as CAN (Controller Area Network), LIN (Local Interconnect Network), LAN (Local Area Network), FlexRay®, and Ethernet®. The communication network 41 may be used differently depending on the type of data being transmitted. For example, CAN may be applied to data related to vehicle control, and Ethernet may be applied to large-capacity data. In addition, the various components of the vehicle control system 11 may be directly connected using wireless communication methods intended for relatively short-range communication, such as Near Field Communication (NFC) or Bluetooth®, without going through the communication network 41.

[0165] In the following, when each part of the vehicle control system 11 communicates via the communication network 41, the description of the communication network 41 will be omitted. For example, when the vehicle control ECU 21 and the communication unit 22 communicate via the communication network 41, it will simply be described as the vehicle control ECU 21 and the communication unit 22 communicating.

[0166] The vehicle control ECU 21 is composed of various processors, such as a CPU (Central Processing Unit) and an MPU (Micro Processing Unit). The vehicle control ECU 21 controls the functions of the entire vehicle control system 11 or a part of it.

[0167] The communication unit 22 communicates with various devices inside and outside the vehicle, other vehicles, servers, base stations, etc., and sends and receives various types of data. At this time, the communication unit 22 can communicate using multiple communication methods.

[0168] A brief explanation will be given regarding the external communication capabilities of the communication unit 22. The communication unit 22 communicates with servers located on an external network (hereinafter referred to as "external servers") via a base station or access point using wireless communication methods such as 5G (fifth-generation mobile communication system), LTE (Long Term Evolution), and DSRC (Dedicated Short Range Communications). The external network with which the communication unit 22 communicates is, for example, the internet, a cloud network, or a network specific to a carrier. The communication method used by the communication unit 22 to the external network is not particularly limited, as long as it is a wireless communication method that enables digital two-way communication at a predetermined communication speed and over a predetermined distance.

[0169] Furthermore, for example, the communication unit 22 can communicate with terminals located near the vehicle using P2P (Peer To Peer) technology. Terminals located near the vehicle include, for example, terminals worn by mobile bodies moving at relatively low speeds such as pedestrians and cyclists, terminals installed in fixed locations such as stores, or MTC (Machine Type Communication) terminals. In addition, the communication unit 22 can also perform V2X communication. V2X communication refers to communication between the vehicle and other vehicles, such as vehicle-to-vehicle communication with other vehicles, vehicle-to-infrastructure communication with roadside devices, etc., vehicle-to-home communication with homes, and vehicle-to-pedestrian communication with terminals carried by pedestrians, etc.

[0170] The communication unit 22 can, for example, receive programs from an external source (over the air) to update the software that controls the operation of the vehicle control system 11. The communication unit 22 can also receive map information, traffic information, information about the vehicle 1's surroundings, etc., from an external source. Furthermore, for example, the communication unit 22 can transmit information about the vehicle 1 and information about the vehicle 1's surroundings to an external source. Information about the vehicle 1 that the communication unit 22 transmits to an external source includes, for example, data indicating the status of the vehicle 1 and recognition results from the recognition unit 73. Furthermore, for example, the communication unit 22 can perform communications corresponding to vehicle emergency notification systems such as e-Call.

[0171] For example, the communication unit 22 receives electromagnetic waves transmitted by road traffic information communication systems (VICS (Vehicle Information and Communication System) (registered trademark)) such as radio beacons, optical beacons, and FM multiplex broadcasting.

[0172] A brief explanation will be given regarding the communication capabilities of the communication unit 22 with the vehicle interior. The communication unit 22 can communicate with various devices in the vehicle, for example, using wireless communication. The communication unit 22 can communicate wirelessly with devices in the vehicle using communication methods that enable digital bidirectional communication at a predetermined or higher communication speed via wireless communication, such as wireless LAN, Bluetooth, NFC, and WUSB (Wireless USB). Not limited to these, the communication unit 22 can also communicate with various devices in the vehicle using wired communication. For example, the communication unit 22 can communicate with various devices in the vehicle via wired communication through a cable connected to a connection terminal (not shown). The communication unit 22 can communicate with various devices in the vehicle using communication methods that enable digital bidirectional communication at a predetermined or higher communication speed via wired communication, such as USB (Universal Serial Bus), HDMI (High-Definition Multimedia Interface) (registered trademark), and MHL (Mobile High-definition Link).

[0173] Here, "devices inside the vehicle" refers to, for example, devices inside the vehicle that are not connected to the communication network 41. Examples of devices inside the vehicle include mobile devices and wearable devices owned by the driver or other users inside the vehicle, and information devices that are brought into the vehicle and temporarily installed.

[0174] The map information storage unit 23 stores either or both maps acquired from external sources and maps created by the vehicle 1. For example, the map information storage unit 23 stores high-precision three-dimensional maps, global maps with lower precision than high-precision maps but covering a wide area, and so on.

[0175] High-precision maps include, for example, dynamic maps, point cloud maps, and vector maps. A dynamic map is, for example, a map consisting of four layers: dynamic information, semi-dynamic information, semi-static information, and static information, and is provided to vehicle 1 from an external server. A point cloud map is a map composed of point clouds (point cloud data). A vector map is a map adapted for automated driving by mapping traffic information such as the location of lanes and traffic lights to a point cloud map.

[0176] The point cloud map and vector map may be provided from, for example, an external server, or they may be created in the vehicle 1 as maps for matching with the local map described later, based on sensing results from the camera 51, radar 52, LiDAR 53, etc., and stored in the map information storage unit 23. In addition, if high-precision maps are provided from an external server, in order to reduce communication capacity, map data of, for example, several hundred square meters relating to the planned route that the vehicle 1 will travel will be acquired from the external server.

[0177] The location information acquisition unit 24 receives GNSS (Global Navigation Satellite System) signals from GNSS satellites and acquires the location information of the vehicle 1. The acquired location information is supplied to the driving automation control unit 29. The location information acquisition unit 24 is not limited to using GNSS signals; for example, it may acquire location information using beacons.

[0178] The external recognition sensor 25 is equipped with various sensors used to recognize the external conditions of the vehicle 1, and supplies sensor data from each sensor to various parts of the vehicle control system 11. The types and number of sensors equipped in the external recognition sensor 25 are arbitrary.

[0179] For example, the external recognition sensor 25 includes a camera 51, a radar 52, a LiDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging) 53, and an ultrasonic sensor 54. However, the external recognition sensor 25 may also be configured to include one or more of the cameras 51, radar 52, LiDAR 53, and ultrasonic sensor 54. The number of cameras 51, radar 52, LiDAR 53, and ultrasonic sensor 54 is not particularly limited as long as it is a number that can be realistically installed in the vehicle 1. Furthermore, the types of sensors included in the external recognition sensor 25 are not limited to this example, and the external recognition sensor 25 may include other types of sensors. Examples of the sensing areas of each sensor included in the external recognition sensor 25 will be described later.

[0180] The shooting method of camera 51 is not particularly limited. For example, various types of cameras capable of distance measurement, such as ToF (Time Of Flight) cameras, stereo cameras, monocular cameras, and infrared cameras, can be applied to camera 51 as needed. However, camera 51 may also be used simply for acquiring images, regardless of distance measurement.

[0181] Furthermore, for example, the external recognition sensor 25 may include an environmental sensor for detecting the environment relative to the vehicle 1. The environmental sensor is a sensor for detecting the environment such as weather, climate, and brightness, and may include various sensors such as a raindrop sensor, fog sensor, sunshine sensor, snow sensor, and illuminance sensor.

[0182] Furthermore, for example, the external recognition sensor 25 includes a microphone used for detecting sounds around the vehicle 1 and the location of sound sources.

[0183] The in-vehicle sensor 26 is equipped with various sensors for detecting information inside the vehicle and supplies sensor data from each sensor to various parts of the vehicle control system 11. The types and number of sensors equipped with the in-vehicle sensor 26 are not particularly limited as long as they are types and numbers that can realistically be installed in the vehicle 1.

[0184] For example, the in-vehicle sensor 26 can be equipped with one or more sensors from among a camera, radar, seat sensor, steering wheel sensor, microphone, and biosensor. The camera equipped in the in-vehicle sensor 26 can be a camera of various imaging types capable of distance measurement, such as a ToF camera, stereo camera, monocular camera, or infrared camera. However, it is not limited to these, and the camera equipped in the in-vehicle sensor 26 may simply be for acquiring images, regardless of distance measurement. The biosensor equipped in the in-vehicle sensor 26 is installed, for example, on the seat or steering wheel, and detects various biometric information of the user.

[0185] The vehicle sensor 27 is equipped with various sensors for detecting the state of the vehicle 1 and supplies sensor data from each sensor to various parts of the vehicle control system 11. The types and number of sensors equipped with the vehicle sensor 27 are not particularly limited as long as they are of a type and number that can be realistically installed on the vehicle 1.

[0186] For example, the vehicle sensor 27 includes a speed sensor, an acceleration sensor, an angular velocity sensor (gyro sensor), and an inertial measurement unit (IMU) that integrates them. For example, the vehicle sensor 27 includes a steering angle sensor for detecting the steering angle of the steering wheel, a yaw rate sensor, an accelerator sensor for detecting the amount of operation of the accelerator pedal, and a brake sensor for detecting the amount of operation of the brake pedal. For example, the vehicle sensor 27 includes a rotation sensor for detecting the rotation speed of the engine or motor, an air pressure sensor for detecting the air pressure of the tires, a slip ratio sensor for detecting the slip ratio of the tires, and a wheel speed sensor for detecting the rotation speed of the wheels. For example, the vehicle sensor 27 includes a battery sensor for detecting the remaining charge and temperature of the battery, and an impact sensor for detecting external impacts.

[0187] The storage unit 28 includes at least one of a non-volatile storage medium and a volatile storage medium, and stores data and programs. The storage unit 28 is used as, for example, an EEPROM (Electrically Erasable Programmable Read Only Memory) and a RAM (Random Access Memory), and as the storage medium, magnetic storage devices such as HDDs (Hard Disk Drives), semiconductor storage devices, optical storage devices, and magneto-optical storage devices can be applied. The storage unit 28 stores various programs and data used by each part of the vehicle control system 11. For example, the storage unit 28 is equipped with an EDR (Event Data Recorder) and a DSSAD (Data Storage System for Automated Driving), and stores information about the vehicle 1 before and after an event such as an accident, and information acquired by the in-vehicle sensors 26.

[0188] The automated driving control unit 29 controls the automated driving functions of the vehicle 1. For example, the automated driving control unit 29 includes an analysis unit 61, an action planning unit 62, and an operation control unit 63.

[0189] The analysis unit 61 performs analysis processing on the vehicle 1 and its surroundings. The analysis unit 61 includes a self-position estimation unit 71, a sensor fusion unit 72, and a recognition unit 73.

[0190] The self-position estimation unit 71 estimates the vehicle's position based on sensor data from the external recognition sensor 25 and a high-precision map stored in the map information storage unit 23. For example, the self-position estimation unit 71 generates a local map based on sensor data from the external recognition sensor 25 and estimates the vehicle's position by matching the local map with the high-precision map. The position of the vehicle 1 is based on, for example, the center of the rear wheel relative to the axle.

[0191] Local maps are, for example, three-dimensional high-precision maps created using technologies such as SLAM (Simultaneous Localization and Mapping), occupancy grid maps, etc. Three-dimensional high-precision maps are, for example, the point cloud maps mentioned above. Occupancy grid maps divide the three-dimensional or two-dimensional space around vehicle 1 into grids of a predetermined size and show the occupancy status of objects on a grid-by-grid basis. The occupancy status of objects is indicated, for example, by the presence or absence of an object or the probability of its existence. Local maps are also used, for example, in the detection and recognition processing of the external conditions of vehicle 1 by the recognition unit 73.

[0192] The self-position estimation unit 71 may estimate the vehicle 1's own position based on the position information acquired by the position information acquisition unit 24 and the sensor data from the vehicle sensor 27.

[0193] The sensor fusion unit 72 performs sensor fusion processing to obtain information by combining multiple different types of sensor data (for example, image data supplied from the camera 51 and sensor data supplied from the radar 52). Methods for combining different types of sensor data include composite, integrated, fused, and combined.

[0194] The recognition unit 73 performs a detection process to detect the external conditions of the vehicle 1, and a recognition process to recognize the external conditions of the vehicle 1.

[0195] For example, the recognition unit 73 performs detection and recognition processing of the external conditions of the vehicle 1 based on information from the external recognition sensor 25, information from the self-position estimation unit 71, information from the sensor fusion unit 72, etc.

[0196] Specifically, for example, the recognition unit 73 performs detection and recognition processing of objects around the vehicle 1. Object detection processing includes, for example, detecting the presence, size, shape, position, and movement of objects. Object recognition processing includes, for example, recognizing attributes such as the type of object or identifying a specific object. However, detection processing and recognition processing are not necessarily clearly separated and may overlap.

[0197] For example, the recognition unit 73 detects objects around the vehicle 1 by performing clustering, which classifies the point cloud based on sensor data from the radar 52 or LiDAR 53 into clusters of points. This allows the presence, size, shape, and position of objects around the vehicle 1 to be detected.

[0198] For example, the recognition unit 73 detects the movement of objects around the vehicle 1 by performing tracking that follows the movement of clusters of points classified by clustering. This allows the speed and direction of travel (movement vector) of objects around the vehicle 1 to be detected.

[0199] For example, the recognition unit 73 detects or recognizes vehicles, people, bicycles, obstacles, structures, roads, traffic lights, traffic signs, road markings, etc., based on image data supplied from the camera 51. The recognition unit 73 may also recognize the types of objects around the vehicle 1 by performing recognition processing such as semantic segmentation.

[0200] For example, the recognition unit 73 can perform traffic rule recognition processing around the vehicle 1 based on the map stored in the map information storage unit 23, the self-position estimation result by the self-position estimation unit 71, and the recognition result of objects around the vehicle 1 by the recognition unit 73. Through this processing, the recognition unit 73 can recognize the location and status of traffic lights, the content of traffic signs and road markings, the content of traffic regulations, and the lanes that can be driven on.

[0201] For example, the recognition unit 73 can perform recognition processing of the environment surrounding the vehicle 1. The surrounding environment that the recognition unit 73 is intended to recognize may include weather, temperature, humidity, brightness, and road surface conditions.

[0202] The action planning unit 62 creates an action plan for vehicle 1. For example, the action planning unit 62 creates an action plan by performing route planning and route following processes.

[0203] Furthermore, path planning includes global path planning and local path planning. Global path planning involves planning a rough route from the start to the goal. Local path planning, also known as track planning, involves generating a track that allows the vehicle 1 to travel safely and smoothly in its vicinity, taking into account the vehicle's motion characteristics along the planned route.

[0204] Route following is the process of planning actions to safely and accurately travel along the route planned by the route planner within the planned time. The action planning unit 62 can, for example, calculate the target speed and target angular velocity of the vehicle 1 based on the results of this route following process.

[0205] The motion control unit 63 controls the operation of the vehicle 1 in order to realize the action plan created by the action planning unit 62.

[0206] For example, the motion control unit 63 controls the steering control unit 81, brake control unit 82, and drive control unit 83, which are included in the vehicle control unit 32 described later, to perform lateral and longitudinal vehicle motion control so that the vehicle 1 moves along the trajectory calculated by the trajectory plan. For example, the motion control unit 63 performs control aimed at driver assistance functions such as collision avoidance or impact mitigation, follow-me driving, vehicle speed maintenance driving, collision warning for the vehicle, lane departure warning for the vehicle, and driving automation such as driving without operation by the driver or remote driver.

[0207] The DMS 30 performs driver authentication processing and driver status recognition processing based on sensor data from the in-vehicle sensors 26 and input data input to the HMI 31, which will be described later. The driver status to be recognized may include, for example, physical condition, level of alertness, level of concentration, level of fatigue, gaze direction, level of intoxication, driving operation, and posture.

[0208] Furthermore, the DMS 30 may perform authentication processing for users other than the driver and recognition processing for the status of such users. Also, for example, the DMS 30 may perform recognition processing of the conditions inside the vehicle based on sensor data from the in-vehicle sensor 26. Examples of conditions inside the vehicle to be recognized include temperature, humidity, brightness, and odor.

[0209] HMI31 handles the input of various data and instructions, and presents various data to the user.

[0210] A brief explanation of data input by HMI31 is provided. HMI31 is equipped with an input device for a person to input data. HMI31 generates input signals based on the data and instructions input by the input device and supplies them to each part of the vehicle control system 11. HMI31 is equipped with operators such as a touch panel, buttons, switches, and levers as input devices. However, HMI31 may further be equipped with input devices that allow information to be input by methods other than manual operation, such as voice or gestures. Furthermore, HMI31 may use external connected devices such as a remote control device using infrared or radio waves, or a mobile device or wearable device that corresponds to the operation of the vehicle control system 11, as input devices.

[0211] A brief explanation of how HMI31 presents data is provided below. HMI31 generates visual, auditory, and tactile information for the user or those outside the vehicle. HMI31 also performs output control, managing the output, content, timing, and method of each generated piece of information. As visual information, HMI31 generates and outputs information shown by images and light, such as operation screens, vehicle status displays, warning displays, and monitor images showing the surroundings of vehicle 1. As auditory information, HMI31 generates and outputs information shown by sound, such as voice guidance, warning sounds, and warning messages. Furthermore, as tactile information, HMI31 generates and outputs information that is perceived by the user's sense of touch, such as force, vibration, and movement.

[0212] As output devices for visual information output by HMI31, for example, a display device that presents visual information by displaying images itself, or a projector device that presents visual information by projecting images, can be applied. In addition to display devices with ordinary displays, the display device may also be a device that displays visual information within the user's field of view, such as a head-up display, a transparent display, or a wearable device equipped with AR (Augmented Reality) functionality. Furthermore, HMI31 can also use display devices of the vehicle 1, such as a navigation system, instrument panel, CMS (Camera Monitoring System), electronic mirror, or lamps, as output devices for visual information output.

[0213] As output devices for HMI31 to output auditory information, for example, audio speakers, headphones, and earphones can be used.

[0214] As an output device for HMI31 to output tactile information, for example, a haptic element using haptic technology can be applied. The haptic element can be installed in parts that the user touches, such as the steering wheel or seat.

[0215] The vehicle control unit 32 controls various parts of the vehicle 1. The vehicle control unit 32 includes a steering control unit 81, a brake control unit 82, a drive control unit 83, a body system control unit 84, a light control unit 85, and a horn control unit 86.

[0216] The steering control unit 81 detects and controls the state of the steering system of the vehicle 1. The steering system includes, for example, a steering mechanism with a steering wheel, an electric power steering system, etc. The steering control unit 81 includes, for example, a steering ECU that controls the steering system, an actuator that drives the steering system, etc.

[0217] The brake control unit 82 detects and controls the state of the brake system of the vehicle 1. The brake system includes, for example, a brake mechanism including a brake pedal, an ABS (Antilock Brake System), a regenerative braking mechanism, etc. The brake control unit 82 includes, for example, a brake ECU that controls the brake system, an actuator that drives the brake system, etc.

[0218] The drive control unit 83 detects and controls the state of the vehicle's drive system. The drive system includes, for example, an accelerator pedal, a drive force generating device for generating driving force such as an internal combustion engine or drive motor, and a drive force transmission mechanism for transmitting driving force to the wheels. The drive control unit 83 also includes, for example, a drive ECU for controlling the drive system and an actuator for driving the drive system.

[0219] The body system control unit 84 detects and controls the state of the body system of the vehicle 1. The body system includes, for example, a keyless entry system, a smart key system, power window devices, power seats, an air conditioning system, airbags, seat belts, a shift lever, etc. The body system control unit 84 also includes, for example, a body system ECU that controls the body system, actuators that drive the body system, etc.

[0220] The light control unit 85 detects and controls the state of various lights on the vehicle 1. Examples of lights to be controlled include headlights, taillights, fog lights, turn signals, brake lights, projections, and bumper displays. The light control unit 85 includes a light ECU for controlling the lights and actuators for driving the lights.

[0221] The horn control unit 86 detects and controls the state of the car horn of the vehicle 1. The horn control unit 86 includes, for example, a horn ECU for controlling the car horn, an actuator for driving the car horn, and so on.

[0222] Figure 36 shows an example of the sensing area of ​​the external recognition sensor 25 in Figure 35, including the camera 51, radar 52, LiDAR 53, and ultrasonic sensor 54. In Figure 36, the vehicle 1 is schematically shown as viewed from above, with the left end being the front end of the vehicle 1 and the right end being the rear end of the vehicle 1.

[0223] Sensing regions 101F and 101B show examples of sensing regions of the ultrasonic sensor 54. Sensing region 101F covers the area around the front end of the vehicle 1 by multiple ultrasonic sensors 54. Sensing region 101B covers the area around the rear end of the vehicle 1 by multiple ultrasonic sensors 54.

[0224] The sensing results in sensing area 101F and sensing area 101B are used, for example, to assist in parking the vehicle 1.

[0225] Sensing areas 102F to 102B show examples of sensing areas for short-range or medium-range radar 52. Sensing area 102F covers a position further in front of vehicle 1 than sensing area 101F. Sensing area 102B covers a position further in rear of vehicle 1 than sensing area 101B. Sensing area 102L covers the rear periphery of the left side of vehicle 1. Sensing area 102R covers the rear periphery of the right side of vehicle 1.

[0226] The sensing results in sensing region 102F are used, for example, to detect vehicles or pedestrians in front of vehicle 1. The sensing results in sensing region 102B are used, for example, to prevent collisions behind vehicle 1. The sensing results in sensing regions 102L and 102R are used, for example, to detect objects in blind spots to the sides of vehicle 1.

[0227] Sensing areas 103F to 103B show examples of sensing areas by the camera 51. Sensing area 103F covers a position further in front of the vehicle 1 than sensing area 102F. Sensing area 103B covers a position further in rear of the vehicle 1 than sensing area 102B. Sensing area 103L covers the periphery of the left side of the vehicle 1. Sensing area 103R covers the periphery of the right side of the vehicle 1.

[0228] The sensing results in sensing region 103F can be used, for example, for recognition of traffic lights and traffic signs, lane departure prevention support systems, and automatic headlight control systems. The sensing results in sensing region 103B can be used, for example, for parking assistance and surround view systems. The sensing results in sensing regions 103L and 103R can be used, for example, for surround view systems.

[0229] Sensing area 104 shows an example of the sensing area of ​​LiDAR 53. Sensing area 104 covers a position further in front of vehicle 1 than sensing area 103F. On the other hand, sensing area 104 has a narrower range in the left-right direction than sensing area 103F.

[0230] The sensing results in the sensing region 104 are used, for example, to detect objects such as surrounding vehicles.

[0231] Sensing area 105 shows an example of the sensing area of ​​the long-range radar 52. Sensing area 105 covers a position further in front of vehicle 1 than sensing area 104. On the other hand, sensing area 105 has a narrower range in the left-right direction than sensing area 104.

[0232] The sensing results in the sensing area 105 are used, for example, for ACC (Adaptive Cruise Control), emergency braking, collision avoidance, etc.

[0233] Furthermore, the sensing areas of the camera 51, radar 52, LiDAR 53, and ultrasonic sensor 54 included in the external recognition sensor 25 may take various configurations other than those shown in Figure 36. Specifically, the ultrasonic sensor 54 may be configured to sense the sides of the vehicle 1, or the LiDAR 53 may be configured to sense the rear of the vehicle 1. Also, the installation positions of each sensor are not limited to the examples described above. In addition, there may be one or more sensors.

[0234] In the above-described in-vehicle control system 11, the speed detection device 100 of this disclosure can be applied to the radar 52 of the external recognition sensor 25.

[0235] It is also possible to combine at least two of the feature features of the present technology described above. In other words, the various feature features described in each embodiment may be combined arbitrarily, regardless of the specific embodiment. Furthermore, the various effects described above are merely examples and not limiting, and other effects may also be exhibited.

[0236] In this disclosure, "same," "equal," "orthogonal," etc., are concepts that include "substantially the same," "substantially equal," "substantially orthogonal," etc. For example, states that fall within a predetermined range (e.g., a range of ±10%) based on "exactly the same," "exactly equal," "exactly orthogonal," etc.

[0237] Furthermore, this technology can also be configured as follows: (1) A speed detection device comprising: a plurality of transmitting antennas that transmit a plurality of chirp signals; a plurality of receiving antennas that receive the plurality of chirp signals reflected by an object; a chirp control unit that controls the plurality of chirp signals so that each chirp signal is transmitted simultaneously from the plurality of transmitting antennas while changing the combination of phases of the plurality of chirp signals for each of the plurality of time slots; and a speed detection unit that detects the speed of the object based on signals from the plurality of receiving antennas, wherein the chirp control unit sets at least two of the intervals of the time slots in which the combination of phases of the plurality of chirp signals are the same to different intervals. (2) The speed detection device according to (1), wherein the chirp control unit sets a repeating period in which a plurality of time slots in which the combination of phases of the plurality of chirp signals are the same are arranged. (3) The speed detection device according to (2), wherein the chirp control unit sets a plurality of different interval values ​​sequentially as the intervals of the time slots in which the combination of phases of the plurality of chirp signals are the same in the repeating period. (4) A speed detection device according to any one of (1) to (3), wherein the plurality of time slots include a plurality of individual slots equal to the number of transmitting antennas, and the combinations of the phases of the plurality of chirp signals are different from each other. (5) A speed detection device according to (4), wherein the chirp control unit sets a plurality of slot sets, each including the plurality of individual slots, such that the order of the plurality of individual slots is different in each slot set. (6) A speed detection device according to (5), wherein the chirp control unit sets at least three or more slot sets.(7) A speed detection device according to any one of (1) to (6), wherein the speed detection unit generates a plurality of first received signals corresponding to a plurality of individual slots based on signals from a plurality of receiving antennas while assuming a plurality of speed aliasing values ​​due to phase aliasing, and generates a plurality of second received signals corresponding to a plurality of transmitting antennas by synthesizing the plurality of first received signals using a decoding formula corresponding to the combination of phases of the plurality of chirp signals. (8) A speed detection device according to (7), wherein the speed detection unit adds the plurality of second received signals and determines the speed aliasing value when the amplitude of the addition result is maximum as the true speed aliasing value. (9) A speed detection device according to (7), wherein the speed detection unit performs a Fourier transform on the plurality of second received signals and determines the speed aliasing value when the peak of the Fourier transform is maximum as the true speed aliasing value. (10) A speed detection device according to any one of (1) to (9), wherein the interval between time slots in which the combinations of phases of the plurality of chirp signals are the same is an integer multiple of the time width of the chirp signals. (11) A speed detection device according to any one of (1) to (9), wherein the interval between time slots in which the combinations of phases of the plurality of chirp signals are the same is a non-integer multiple of the time width of the chirp signals. (12) A speed detection device according to any one of (1) to (11), wherein the chirp control unit sets the phase of the chirp signals using the BPM (Binary Phase Multiplexing) method. (13) Information processing device comprising: a chirp control unit that controls a plurality of chirp signals so that each chirp signal is transmitted simultaneously from a plurality of transmitting antennas, while changing the combination of phases of the plurality of chirp signals transmitted from a plurality of transmitting antennas for each of a plurality of time slots; and a velocity detection unit that detects the velocity of an object based on signals from a plurality of receiving antennas that receive the plurality of chirp signals reflected by the object, wherein the chirp control unit sets at least two of the intervals of the time slots in which the combination of phases of the plurality of chirp signals is the same to different intervals.(14) A speed detection method comprising the steps of: controlling a plurality of chirp signals so that each chirp signal is transmitted simultaneously from a plurality of transmitting antennas, while changing the combination of phases of the plurality of chirp signals transmitted from a plurality of transmitting antennas for each of a plurality of time slots; and detecting the speed of an object based on signals from a plurality of receiving antennas that receive the plurality of chirp signals reflected by the object, wherein in the step of controlling the plurality of chirp signals, at least two of the intervals of the time slots in which the combination of phases of the plurality of chirp signals are the same are set to different intervals.

[0238] TX, TX1-TX8...Transmitting antennas Tx, Tx1-Tx8...Chirp signals RX...Receiving antenna 2...Object 5...Time slot 6...Individual slots 7...Slot set 100...Speed ​​detection device 120...Information processing device 121...Chirp control unit 122...Beat signal generation unit 123...Signal processing unit

Claims

1. A speed detection device comprising: a plurality of transmitting antennas that transmit a plurality of chirp signals; a plurality of receiving antennas that receive the plurality of chirp signals reflected by an object; a chirp control unit that controls the plurality of chirp signals so that each chirp signal is transmitted simultaneously from the plurality of transmitting antennas while changing the combination of phases of the plurality of chirp signals for each of a plurality of time slots; and a speed detection unit that detects the speed of the object based on signals from the plurality of receiving antennas, wherein the chirp control unit sets at least two of the time slot intervals in which the combination of phases of the plurality of chirp signals is the same to different intervals.

2. A speed detection device according to claim 1, wherein the chirp control unit sets a repeating period in which a plurality of time slots are arranged such that the combination of phases of the plurality of chirp signals is the same.

3. A speed detection device according to claim 2, wherein the chirp control unit sequentially sets a plurality of different interval values ​​as the interval between time slots in which the combination of phases of the plurality of chirp signals is the same in the repeating period.

4. A speed detection device according to claim 1, wherein the plurality of time slots include a plurality of individual slots equal to the number of transmitting antennas, wherein the combinations of phases of the plurality of chirp signals are different from each other.

5. A speed detection device according to claim 4, wherein the chirp control unit sets a plurality of slot sets, each including the plurality of individual slots, such that the order of the plurality of individual slots is different in each slot set.

6. A speed detection device according to claim 5, wherein the chirp control unit sets at least three or more slot sets.

7. A speed detection device according to claim 1, wherein the speed detection unit generates a plurality of first received signals corresponding to a plurality of individual slots based on signals from the plurality of receiving antennas while assuming a plurality of speed aliasing values ​​due to phase aliasing, and generates a plurality of second received signals corresponding to the plurality of transmitting antennas by synthesizing the plurality of first received signals using a decoding formula corresponding to the combination of phases of the plurality of chirp signals.

8. A speed detection device according to claim 7, wherein the speed detection unit adds up the plurality of second received signals and determines the speed aliasing value when the amplitude of the sum is maximum as the true speed aliasing value.

9. A speed detection device according to claim 7, wherein the speed detection unit performs a Fourier transform on the plurality of second received signals and determines the speed aliasing value when the peak of the Fourier transform is maximum as the true speed aliasing value.

10. A speed detection device according to claim 1, wherein the interval between time slots in which the combinations of phases of the plurality of chirp signals are the same is an integer multiple of the time width of the chirp signal.

11. A speed detection device according to claim 1, wherein the interval between the time slots in which the combinations of phases of the plurality of chirp signals are the same is a non-integer multiple of the time width of the chirp signals.

12. A speed detection device according to claim 1, wherein the chirp control unit sets the phase of the chirp signal using the BPM (Binary Phase Multiplexing) method.

13. An information processing device comprising: a chirp control unit that controls a plurality of chirp signals so that each chirp signal is transmitted simultaneously from a plurality of transmitting antennas, while changing the combination of phases of the plurality of chirp signals transmitted from a plurality of transmitting antennas for each of a plurality of time slots; and a velocity detection unit that detects the velocity of an object based on signals from a plurality of receiving antennas that receive the plurality of chirp signals reflected by the object, wherein the chirp control unit sets at least two of the intervals of the time slots in which the combination of phases of the plurality of chirp signals is the same to different intervals.

14. A speed detection method comprising: controlling a plurality of chirp signals so that each chirp signal is transmitted simultaneously from a plurality of transmitting antennas, while changing the combination of phases of the plurality of chirp signals transmitted from a plurality of transmitting antennas for each of a plurality of time slots; and detecting the speed of an object based on signals from a plurality of receiving antennas that receive the plurality of chirp signals reflected by the object, wherein in the step of controlling the plurality of chirp signals, at least two of the time slot intervals in which the combination of phases of the plurality of chirp signals are the same are set to different intervals.

Images