JP6980979B2 - Radar device and target detection method - Google Patents

Description

The disclosed embodiments relate to radar devices and target detection methods.

Conventionally, the transmitted wave of the frequency-modulated modulated wave is transmitted, the transmitted wave receives the reflected wave reflected by the target, the received signal generated by signal processing the reflected wave, and each direction in which the target can exist. There is a radar device that derives the direction in which the target exists based on the mode vector created in.

Such a radar device sequentially calculates an angle spectrum indicating the direction of the target based on the reflected wave and the mode vector, and derives the direction associated with the mode vector having the highest angle spectrum as the direction in which the target exists. (See, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2012-185039

However, in the conventional radar device, when there are a plurality of targets at positions having substantially the same distance from the radar device, it may not be possible to derive the respective orientation of each target.

One aspect of the embodiment is made in view of the above, and is a radar device capable of deriving the direction of each of a plurality of targets having substantially the same distance from the radar device and target detection. The purpose is to provide a method.

The radar device according to one embodiment includes a storage unit, a transmission unit, a reception unit, and a derivation unit. The storage unit stores information in which the mode vector created for each combination of directions in which a plurality of targets can exist simultaneously within the range of directions in which the target can be detected and the combination of the directions are associated with each other. The transmitter transmits the transmitted wave. The receiving unit receives the reflected wave whose transmitted wave is reflected by the target. The derivation unit sequentially calculates an angle spectrum indicating the direction of the target based on the reflected wave and the mode vector, and simultaneously exists a combination of directions associated with the mode vector having the highest angle spectrum. Derived as a combination of target orientations.

The radar device and the target detection method according to one aspect of the embodiment can derive the direction of each of a plurality of targets having substantially the same distance from the radar device.

FIG. 1 is a block diagram showing an example of the configuration of the radar device according to the embodiment. FIG. 2 is an explanatory diagram showing an example of mode vector information according to the embodiment. FIG. 3 is an explanatory diagram showing a method of deriving the direction of a general radar device according to the inverse proportion of the embodiment. FIG. 4 is an explanatory diagram showing a method of deriving the direction of a general radar device according to the inverse proportion of the embodiment. FIG. 5 is an explanatory diagram showing an example of mode vector information according to the embodiment. FIG. 6 is an explanatory diagram of a method for deriving the direction of the radar device according to the embodiment. FIG. 7 is an explanatory diagram showing an example of mode vector information according to the embodiment. FIG. 8 is a flowchart showing a process executed by the radar device according to the embodiment. FIG. 9 is a flowchart showing a process executed by the radar device according to the embodiment.

Hereinafter, embodiments of the radar device and the target detection method disclosed in the present application will be described in detail with reference to the accompanying drawings. The present invention is not limited to the embodiments shown below. First, an example of the configuration of the radar device 1 according to the embodiment will be described with reference to FIG.

FIG. 1 is a block diagram showing a radar device 1 according to an embodiment. Note that, in FIG. 1, only the components necessary for explaining the features of the present embodiment are represented by functional blocks, and the description of general components is omitted.

In other words, each component shown in FIG. 1 is a functional concept and does not necessarily have to be physically configured as shown. For example, the specific form of distribution / integration of each functional block is not limited to the one shown in the figure, and all or part of it is functionally or physically distributed in any unit according to various loads and usage conditions. -It is possible to integrate and configure.

The radar device 1 is mounted on a vehicle (hereinafter referred to as "own vehicle") and detects a target existing around the own vehicle. The radar device 1 can also be mounted on an aircraft or a ship to detect surrounding objects.

Hereinafter, a case where the radar device 1 is a device for detecting a target by an FCM (Fast Chip Modulation) method will be described. The method by which the radar device 1 detects a target is not limited to the FCM method, and may be an FM-CW method.

As shown in FIG. 1, the radar device 1 includes a transmission unit 2 and a transmission antenna 4 as components constituting the transmission system. The transmission unit 2 includes a signal generation unit 21 and an oscillator 22.

Further, the radar device 1 includes receiving antennas 5-1 to 5-4 and receiving units 6-1 to 6-4 as components constituting the receiving system. The receiving units 6-1 to 6-4 each include a mixer 61 and an A / D conversion unit 62, respectively. Further, the radar device 1 includes a signal processing device 7 as a component constituting the signal processing system.

In the following, for the sake of simplification of the description, when the term "reception antenna 5" is simply described, the reception antennas 5-1 to 5-4 are collectively referred to. The same applies to the "reception unit 6".

The transmission unit 2 performs a process of generating a transmission wave. The signal generation unit 21 generates a modulated signal for generating a transmission wave whose frequency changes periodically like a saw wave under the control of the transmission control unit 71 provided in the signal processing device 7 described later, and outputs the modulated signal to the oscillator 22. ..

The oscillator 22 generates a transmitted wave (a plurality of continuous chirps) of a modulated wave whose frequency changes periodically based on the modulated signal generated by the signal generation unit 21, and outputs the transmitted wave (a plurality of continuous chirps) to the transmitting antenna 4. ..

The transmitting antenna 4 transmits the transmitted wave generated by the oscillator 22 to, for example, the front of the own vehicle. As shown in FIG. 1, the transmitted wave generated by the oscillator 22 is also distributed to the mixer 61 described later.

The receiving antenna 5 receives the reflected wave arriving from the target by reflecting the transmitted wave transmitted from the transmitting antenna 4 at the target. Each of the receiving units 6 performs pre-stage processing until each received reflected wave is passed to the signal processing device 7.

Specifically, each of the mixers 61 mixes the transmitted wave distributed as described above and the reflected wave received by each of the receiving antennas 5, and obtains the absolute value of the difference between the transmitted wave and the reflected wave. By taking, a beat signal is generated. A corresponding amplifier may be arranged between the receiving antenna 5 and the mixer 61.

The A / D conversion unit 62 digitally converts the beat signal generated by the mixer 61 and outputs the beat signal to the signal processing device 7. The A / D conversion unit 62 converts an analog beat signal into a digital reception signal by AD sampling the beat signal generated by the mixer 61 at a predetermined cycle timing.

The signal processing device 7 includes a transmission control unit 71, a detection unit 72, and a storage unit 73. The storage unit 73 is a storage device such as a hard disk drive, a non-volatile memory, or a register, and stores mode vector information 74.

The mode vector information 74 is information in which the mode vector created for each direction in which the target can exist and the direction of the target are associated with each other, and the direction calculation unit 83 described later derives the direction of the target. Information used in the case. An example of such mode vector information 74 will be described later with reference to FIGS. 2, 5, and 7.

The transmission control unit 71 controls the operation of the signal generation unit 21 so as to generate and output a transmission wave. The detection unit 72 detects the target by calculating the direction of the target, the distance to the target, and the relative speed with the target by the FCM method.

Here, a calculation method in which the detection unit 72 calculates the distance to the target and the relative speed to the target by the FCM method will be briefly described. The detection unit 72 calculates the distance to the target and the relative speed to the target based on the beat signal input from each A / D conversion unit 62.

At this time, a beat signal is input to the detection unit 72 for each cycle (chirp) of the transmitted wave. In such a case, the time (delay time) from the transmission of the transmitted wave by the transmitting unit 2 to the reception of the reflected wave reflected by the target by the target is the time between the target and the radar device 1. Since it increases or decreases in proportion to the distance, the frequency of the beat signal is proportional to the distance to the target.

Therefore, when the detection unit 72 performs FFT (Fast Fourier Transform) processing on the beat signal, a peak appears at a frequency position corresponding to the distance of the target in the processing result of the FFT processing.

At this time, in the FFT process, the reception level and the phase information are extracted for each frequency point (hereinafter referred to as "distance BIN") set at a predetermined frequency interval, so that the distance to the target is accurately determined. A peak appears at the distance BIN of the corresponding frequency. Therefore, the detection unit 72 can obtain the distance to the target by detecting the peak frequency.

Further, in the FCM method, when a relative speed is generated between the own vehicle and the target, a phase change according to the Doppler frequency appears between the beat signals sequentially input to the detection unit 72. Therefore, the detection unit 72 detects the Doppler frequency between the beat signals and calculates the relative speed.

For example, when the relative velocity between the radar device 1 and the target is 0, the reflected wave does not have a Doppler component, so that the phases of the reflected waves corresponding to each chirp are all the same. On the other hand, when there is a relative velocity between the radar device 1 and the target, a phase change of the Doppler occurs between the reflected waves corresponding to each chirp. Further, the peak information obtained by FFT processing the beat signal includes this phase information.

Therefore, the detection unit 72 can calculate the Doppler frequency from the phase information by performing the second FFT process in time series for the peak information of the same target obtained from each beat signal. Then, in the processing result of the second FFT processing, a peak appears at the frequency position.

At this time, in the second FFT process, the phase information is extracted at each frequency point (hereinafter referred to as “velocity BIN”) set at a predetermined frequency interval according to the velocity resolution, so that the relative target is relative. A peak appears in the velocity BIN of the frequency corresponding to the velocity. Therefore, the detection unit 72 can obtain the relative speed with the target by detecting the peak frequency.

The detection unit 72 includes, for example, a microcomputer having a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input / output port, and various circuits.

The detection unit 72 includes a plurality of processing units that function by the CPU executing the target detection program stored in the ROM by using the RAM as a work area. Specifically, the detection unit 72 includes an FFT unit 81, a peak extraction unit 82, a direction calculation unit 83, and a distance relative velocity calculation unit 84.

Each processing unit included in the detection unit 72 may be partially or wholly composed of hardware such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array).

The FFT unit 81 performs the first FFT processing on the beat signals sequentially input from the A / D conversion unit 62 of each receiving unit 6, and obtains the processing result for each distance BIN set at a predetermined frequency interval.

Further, the FFT unit 81 performs the second FFT processing for each of a plurality of beat signals for the same distance BIN, and the processing result of the first FFT processing is performed for each speed BIN set at a predetermined frequency interval. demand.

Then, the FFT unit 81 outputs the processing result of the first FFT processing and the processing result of the second FFT processing to the peak extraction unit 82. The peak extraction unit 82 extracts peaks from the processing result of the first FFT processing and the processing result of the second FFT processing, and outputs the peaks to the direction calculation unit 83.

The direction calculation unit 83 derives the direction of the target with respect to the radar device 1 based on the phase difference of each reflected wave received by the plurality of receiving antennas 5, and the derived target direction and the peak extraction unit 82 use the direction calculation unit 83. The extracted peak is output to the distance relative speed calculation unit 84.

The directional calculation unit 83 according to the embodiment is the same by using the mode vector information 74 in which the mode vector created for each directional combination in which a plurality of targets can exist at the same time and the directional combination are associated with each other. It is possible to derive the directions of multiple targets existing at distance positions. An example of the method of deriving the direction by the direction calculation unit 83 will be described after explaining the overall configuration of the radar device 1.

The distance relative speed calculation unit 84 detects the peak frequency extracted from the processing result of the first FFT process input from the peak extraction unit 82 via the orientation calculation unit 83, and the distance at which the peak frequency is detected is detected. The distance corresponding to BIN is derived as the distance to the target.

Further, the distance relative velocity calculation unit 84 detects the peak frequency extracted from the processing result of the second FFT process input from the peak extraction unit 82 via the orientation calculation unit 83, and the peak frequency is detected. The speed corresponding to the speed BIN is derived as the relative speed of the target.

Then, the distance relative speed calculation unit 84 outputs the target information including the distance to the derived target, the relative speed with the target, and the direction of the target derived by the direction calculation unit 83 to the external device. Here, the external device is, for example, a vehicle control device 10.

The vehicle control device 10 is an ECU (Electronic Control Unit) that controls each device of the own vehicle. The vehicle control device 10 is electrically connected to, for example, a vehicle speed sensor 11, a steering angle sensor 12, a throttle 13, and a brake 14.

The vehicle control device 10 controls a vehicle such as ACC (Adaptive Cruise Control) or PCS (Pre-Crash Safety System) based on the target information acquired from the radar device 1.

For example, when performing ACC, the vehicle control device 10 uses the target information acquired from the radar device 1 so that the own vehicle follows the preceding vehicle while maintaining a constant distance from the preceding vehicle. It controls the throttle 13 and the brake 14. Further, the vehicle control device 10 acquires the traveling state of the own vehicle, that is, the vehicle speed, the steering angle, etc., which changes from time to time, from the vehicle speed sensor 11, the steering angle sensor 12, and the like, and feeds them back to the radar device 1.

Further, for example, when the vehicle control device 10 performs PCS, the target information acquired from the radar device 1 is used, and there is a preceding vehicle, a stationary object, or the like having a risk of collision in the traveling direction of the own vehicle. When is detected, the brake 14 is controlled to decelerate the own vehicle. Further, for example, the passenger of the own vehicle is warned by using an alarm device (not shown), or the seat belt in the vehicle interior is pulled in to fix the passenger to the seat.

Next, with reference to FIGS. 2 to 7, an example of a method for deriving the direction by the direction calculation unit 83 according to the embodiment will be described. Here, after explaining a method of deriving the direction by a general radar device for deriving the direction of a target using a mode vector, the method of deriving the direction performed by the direction calculation unit 83 of the radar device 1 according to the embodiment will be described. explain.

2, FIG. 5, and FIG. 7 are explanatory views showing an example of mode vector information according to the embodiment. 3 and 4 are explanatory views showing a method of deriving the direction of a general radar device according to the inverse proportion of the embodiment. FIG. 6 is an explanatory diagram of a method for deriving the direction of the radar device according to the embodiment.

First, the mode vector used by a general radar device will be described. For example, when the radar device includes four receiving antennas arranged at equal intervals, the distance between adjacent receiving antennas is d, with respect to a direction perpendicular to the row direction of the receiving antennas arranged in a row (for example, the traveling direction of the own vehicle). It is assumed that the arrival direction of the reflected wave is θ and the wavelength of the reflected wave is λ.

In such a case, the phase difference φ of the reflected wave received by the adjacent receiving antenna is φ = (2π / λ) dsin (θ). Here, it is assumed that the first receiving antenna, the second receiving antenna, the third receiving antenna, and the fourth receiving antenna are arranged in this order.

At this time, assuming that the amplitude of the reflected wave at a certain time t in the first receiving antenna is a (t), the amplitude of the reflected wave in the second receiving antenna at the same point is a (t) exp [j (2π /). λ) dsin (θ)].

Then, for example, when an ideal reflected wave having an amplitude of 1 arrives from the azimuth θ, considering the reference of the isomoving surface at a certain time as the first receiving antenna, the reflection received by the first receiving antenna at the same time. The phase of the reflected wave received by the other receiving antenna with respect to the wave is as follows.
Second receiving antenna: exp [-j (2π / λ) dsin (θ)]
Third receiving antenna: exp [-j (2π / λ) 2dsin (θ)]
Fourth receiving antenna: exp [-j (2π / λ) 3dsin (θ)]

Therefore, A1 (θ), A2 (θ), A3 (θ), A4 in the mode vector A (θ) = [A1 (θ), A2 (θ), A3 (θ), A4 (θ)] at this time. (Θ) is as follows.
A1 (θ) = 1
A2 (θ) = exp [-j (2π / λ) dsin (θ)]
A3 (θ) = exp [-j (2π / λ) 2dsin (θ)]
A4 (θ) = exp [-j (2π / λ) 3dsin (θ)]

Therefore, in a general radar device, for example, when the range of the direction in which the target can be detected is a range of 10 deg each on the left and right (-10 deg to +10 deg) with the traveling direction of the own vehicle as 0 deg, the mode vector shown in FIG. Memorize information. As shown in FIG. 2, the mode vector information is information in which the mode vector in each direction is associated with each single direction for each 1 deg from −10 deg to +10 deg.

In this way, in a general radar device, a unidirectional mode vector created for each unidirectional direction in which the target can exist within the range of the azimuth in which the target can be detected is associated with the unidirectional direction. The mode vector information is stored.

Then, a general radar device derives the direction of the target based on the peak of the beat signal extracted from the received reflected wave and the mode vector information. Specifically, the radar device first calculates the angle spectrum for each direction based on the peak of the beat signal and each of the unidirectional mode vectors associated with each direction.

Here, since the radar device calculates the angle spectrum for each direction for each 1 deg from −10 deg to +10 deg, a total of 21 angle spectra are calculated. For example, the Capon method or the DBF (Digital Beam Forming) method can be used to calculate the angle spectrum.

Then, the radar device derives the direction associated with the unidirectional mode vector used for calculating the highest angle spectrum among the calculated 10 angle spectra as the direction in which the target exists.

However, in such a general radar device, when a plurality of targets exist at positions having substantially the same distance from the radar device, it may not be possible to derive the respective orientation of each target. Further, when the intensity of the reflected wave reflected by a plurality of targets having substantially the same distance from the radar device is different, the radar device may not be able to derive the direction of the target whose reflected wave intensity is weaker.

For example, as shown in FIG. 3, another vehicle C1 exists in the direction of +2 deg with respect to the traveling direction (0 deg) of the own vehicle C, and the other vehicle C1 is beside the other vehicle C1 (relative to 0 deg which is the traveling direction of the own vehicle C). There may be a person P in the direction of +4 deg). In such a case, the intensity of the reflected wave from the person P is weaker than the intensity of the reflected wave from the other vehicle C1.

Therefore, in a general radar device, when the angle spectrum is calculated, the angle spectrum of the person P is buried in the angle spectrum of the other vehicle C1, and the peak P1 appears only at the point of +2 deg as shown in FIG. Calculate the spectrum. As a result, although the general radar device can derive the direction of the other vehicle C1, the direction of the person P existing beside the other vehicle C1 cannot be derived, and the presence of the person P cannot be detected. ..

Therefore, the radar device 1 according to the embodiment stores the mode vector information 74 including the mode vector information shown in FIG. 5 in the storage unit 73 in addition to the mode vector information shown in FIG. As shown in FIG. 5, the mode vector information further stored by the radar device 1 is created for each combination of all directions in which two targets, target A and target B, can exist at the same time, and for each combination of directions. It is the information associated with the set mode vector.

In the example shown in FIG. 5, the direction in which the target A can exist is -10 deg to +10 deg, and there are 21 in 1 deg increments. For one direction in which the target A can exist, the direction in which the target B can exist is -10 deg. There are 21 in 1 deg increments at ~ + 10 deg. That is, in the example shown in FIG. 5, there are 21 × 21 = 441 combinations of directions in which the target A and the target B can exist at the same time.

The mode vector associated with each combination of directions is obtained by adding each mode vector created for each direction in which the target A exists and each mode vector created for each direction in which the target B exists. Will be created.

For example, for a combination in which the direction of the target A is -10 deg and the direction of the target B is -9 deg,
Mode vector A (-10 deg) = [A1 (-10 deg)), A2 (-10 deg), when the target A exists at -10 deg,
A3 (-10deg), A4 (-10deg)],
Created by adding the mode vector B (-9deg) = [B1 (-9deg), B2 (-9deg), B3 (-9deg), B4 (-9deg)] when the target B exists at -9deg. Next mode vector A (-10 deg) + B (-9 deg) = [A1 (-10 deg) + B1 (-9 deg), A2 (-10 deg) + B2 (-9 deg), A3 (-10 deg) + B3 (-9 deg) , A4 (-10 deg) + B4 (-9 deg)] are associated with each other.

The radar device 1 derives the respective directions of the target A and the target B based on all the mode vectors associated with the combination of the respective directions and the peak of the beat signal. Specifically, the radar device 1 calculates the angle spectrum of 441 based on the mode vector and the peak of the beat signal for each combination of directions. For example, the Capon method or the DBF method can be used to calculate the angle spectrum.

Then, the radar device 1 plots the calculated angle spectrum in, for example, a three-dimensional coordinate system as shown in FIG. In the coordinate system shown in FIG. 6, the X-axis, the Y-axis, and the Z-axis that are orthogonal to each other are defined, and the X-axis is the direction of the target A, the Y-axis is the direction of the target B, and the Z-axis is the angle spectrum.

Here, for example, when the target A exists in the + 2 deg direction and the target B exists in the + 4 deg direction, the peak P2 of the angle spectrum is located at the positions of X = + 2 deg and Y = + 4 deg as shown in FIG. Appears.

Therefore, the radar device 1 sets the combination of the directions associated with the mode vector used for calculating the highest angle spectrum (here, the direction of the target A: + 2 deg, the direction of the target B: + 4 deg) as the target A. It is derived as a combination of the directions in which and the target B exist. In this way, the radar device 1 can derive the direction in which each of the target A and the target B exists based on the peak of the beat signal and the mode vector information shown in FIG.

Here, the radar device 1 calculates the angle spectrum for all combinations of directions (here, 441 ways) to derive the directions of the target A and the target B, but the number of calculated angle spectra is obtained. It is also possible to derive the directions of the target A and the target B by reducing the above.

For example, the radar device 1 first hits the direction in which the target A and the target B exist in the same manner as a general radar device, and the direction near the hit direction, that is, a combination of narrowed directions. The angle spectrum can be calculated for each, and the directions of the target A and the target B can be derived. Specifically, the radar device 1 first derives a rough single direction in which the target A and the target B are present, based on the peak of the beat signal and the mode vector information shown in FIG.

After that, the radar device 1 selects a predetermined number of mode vectors associated with the combination of directions within a predetermined direction range from the derived single direction from the mode vector information shown in FIG. 5, and selects the selected mode vector and beat signal. The angle spectrum is sequentially calculated based on the peak of.

Then, the radar device 1 derives the combination of the directions associated with the mode vector used for calculating the highest angle spectrum among the calculated angle spectra as the combination of the directions in which the target A and the target B exist. do. As a result, the radar device 1 can reduce the processing load by reducing the number of angle spectra calculated for deriving the directions of the target A and the target B.

The mode vector information shown in FIGS. 2 and 5 is an example of the mode vector information 74 stored in the radar device 1. The radar device 1 can also store, for example, other mode vector information shown in FIG. 7.

Other mode vector information is created for each difference in the angular spectrum of each target that can exist at the same time (referred to here as "power difference"). Specifically, as shown in FIG. 7, the other mode vector information is a combination of the directions of the target A and the target B when the angle spectrum of the target B is 10 dB lower than the angle spectrum of the target A. , The mode vectors created for each combination of directions are associated with each other.

Further, the other mode vector information corresponds to the mode vector created for each combination of directions even when the angle spectrum of the target B is 20 dB lower, 30 dB lower, or 40 dB lower than the angle spectrum of the target A. It is attached.

For example, when the angle spectrum of the target B is 10 dB lower than the angle spectrum of the target A, the direction of the target A is -10 deg and the direction of the target B is -9 deg.
Mode vector A (-10 deg) = [A1 (-10 deg)), A2 (-10 deg), when the target A exists at -10 deg,
A3 (-10deg), A4 (-10deg)],
Mode vector B (-9deg) = [B1 (-9deg) -10dB, B2 (-9deg) when the target B exists at -9deg and the angle spectrum of the target B is 10dB lower than the angle spectrum of the target A. ) -10dB, B3 (-9deg) -10dB, B4 (-9deg) -10dB] and the next mode vector A (-10deg) + B (-9deg) -10dB = [A1 (-10deg) ) + B1 (-9deg-10dB), A2 (-10deg) + B2 (-9deg) -10dB, A3 (-10deg) + B3 (-9deg) -10dB, A4 (-10deg) + B4 (-9deg) -10dB] Attached.

The radar device 1 sequentially calculates an angle spectrum for each combination of power difference and direction based on the mode vector associated with the combination of power difference and each direction and the peak of the beat signal.

Then, the radar device 1 derives the direction in which the target A and the target B exist from the combination of the directions associated with the mode vector used for calculating the highest angle spectrum. Further, the radar device 1 derives the highest angle spectrum as the angle spectrum of the target A.

Then, the radar device 1 derives an angle spectrum as the angle spectrum of the target B by subtracting the power difference associated with the mode vector used for calculating the highest angle spectrum from the angle spectrum of the target A.

In this way, the radar device 1 derives the angle spectra of the target A and the target B in addition to the directions of the target A and the target B that exist at the same time by using the mode vector shown in FIG. 7. Can be done.

As a result, the radar device 1 can, for example, have the respective directions of the target A and the target B when the target A and the target B having different reflected wave intensities are present at substantially the same distance from the radar device 1. Can be derived.

As a result, for example, as shown in FIG. 3, the radar device 1 has the other vehicle C1 and the other vehicle C1 when the other vehicle C1 is present diagonally to the right of the own vehicle C and the person P is present beside the other vehicle C1. The exact orientation of person P can be derived.

Next, with reference to FIGS. 8 and 9, a process executed by the radar device 1 according to the embodiment will be described. 8 and 9 are flowcharts showing the processes executed by the radar device 1 according to the embodiment.

The radar device 1 repeatedly executes the process shown in FIG. 8 at a predetermined cycle while the power is turned on. Specifically, as shown in FIG. 8, the radar device 1 first transmits a transmitted wave from the transmitting unit 2 toward the target (step S101). At this time, the radar device 1 inputs a transmitted wave from the transmitting unit 2 to the receiving unit 6.

Subsequently, the radar device 1 receives the reflected wave whose transmitted wave is reflected by the target (step S102). Subsequently, the radar device 1 generates a beat signal based on the transmitted wave and the received wave (step S103). Then, the radar device 1 performs FFT processing on the generated beat signal (step S104).

At this time, the radar device 1 performs FFT processing on the beat signal once, and further performs FFT processing on the result of the first FFT processing. That is, the radar device 1 performs the FFT process twice. Subsequently, the radar device 1 extracts peaks from the processing results of the first and second FFT processing (step S105).

After that, the radar device 1 performs the direction derivation process for deriving the direction in which the target exists based on the peak extracted from the processing result of the first FFT process (step S106). The details of the direction derivation process will be described later with reference to FIG.

Subsequently, the radar device 1 derives the distance to the target based on the processing result of the first FFT processing, and derives the relative velocity with the target based on the processing result of the second FFT processing ( Step S107), the process is terminated.

Next, the direction derivation process executed by the radar device 1 will be described. As shown in FIG. 9, when the radar device 1 starts the direction derivation process, it first acquires a peak from the processing result of the first FFT process of the beat signal (step S201).

Subsequently, the radar device 1 determines whether or not to narrow down the direction in which the target exists (step S202). At this time, the radar device 1 narrows down the direction when the current processing load is equal to or greater than the predetermined processing load, and does not narrow down when the processing load is less than the predetermined processing load.

Then, when the radar device 1 determines that the direction is not narrowed down (step S202, No), the radar device 1 calculates the angle spectrum based on all the mode vectors (step S209), and shifts the process to step S207.

Further, when the radar device 1 determines that the direction is narrowed down (step S202, Yes), the radar device 1 sequentially calculates the angle spectrum for each single direction based on the peak acquired in step S201 and the single direction mode vector. (Step S203).

After that, the radar device 1 acquires the single direction associated with the single direction mode vector having the highest angle spectrum among the calculated angle spectra for each single direction (step S204). Subsequently, the radar device 1 selects a mode vector to be used for deriving each direction of the plurality of targets based on the single direction acquired in step S204 (step S205).

For example, the radar device 1 selects a predetermined number of mode vectors associated with the combination of directions in the vicinity of the single direction acquired in step S204. That is, the radar device 1 selects a plurality of mode vectors to which combinations of directions included in a predetermined directional range including a single directional acquired in step S203 are associated with each other.

Then, the radar device 1 sequentially calculates the angle spectrum for each mode vector based on the peak acquired in step S201 and each of the selected mode vectors (step S206).

After that, the radar device 1 acquires a combination of directions associated with the mode vector having the highest angle spectrum (step S207). Then, the radar device 1 derives the combination of directions acquired in step S207 as a combination of directions of a plurality of targets existing at the same time (step S208), and ends the process.

As described above, the radar device 1 according to the embodiment includes a storage unit 73, a transmission unit 2, a reception unit 6, and an orientation calculation unit 83, which is an example of a derivation unit. The storage unit 73 stores the mode vector information 74 in which the mode vector created for each combination of directions in which a plurality of targets can exist simultaneously within the range of the directions in which the target can be detected and the combination of the directions are associated with each other. Remember.

The transmission unit 2 transmits a transmission wave. The receiving unit 6 receives the reflected wave whose transmitted wave is reflected by the plurality of targets by the plurality of receiving antennas 5. The directional calculation unit 83 sequentially calculates an angle spectrum indicating the direction of the target based on the reflected wave and the mode vector, and simultaneously exists a combination of directions associated with the mode vector having the highest angle spectrum. Derived as a combination of orientations. As a result, the radar device 1 can derive the direction of each of a plurality of targets having substantially the same distance from the radar device 1.

In the above-described embodiment, the case where the radar device 1 derives the directions of two simultaneously existing targets, the target A and the target B, has been described, but each of the three or more targets existing at the same time has been described. It is also possible to derive the orientation.

When the radar device 1 derives each direction of three or more targets existing at the same time, a combination of directions in which three or more targets can exist at the same time and a mode vector created for each combination of directions are used. Stores the mode vector information associated with. Then, the radar device 1 can derive the direction in which each target exists by the same procedure as in the case of deriving each direction in which two targets existing at the same time exist.

Further, in the above-described embodiment, the radar device 1 derives the directions of two targets existing at the same time for all the targets existing within the range of the directions in which the targets can be detected, but the distance from the own vehicle. However, for relatively distant targets, it is less necessary to distinguish between two adjacent targets.

Therefore, for example, the radar device 1 derives the direction of the target using the mode vector information shown in FIG. 5 for the target located at a position where the distance from the own vehicle is within a predetermined distance (for example, 20 m). You may.

Then, the radar device 1 derives the direction of the target using the mode vector information shown in FIG. 2 for the target whose distance from the own vehicle is farther than a predetermined distance (for example, 20 m). You may. As a result, the radar device 1 can further reduce the processing load required for deriving the direction of the target.

Further, in the above-described embodiment, the radar device 1 first narrows down the directions in which the target A and the target B exist in the same manner as a general radar device, and then determines the directions of the target A and the target B. It was derived, but this is just an example.

The radar device 1 is configured to, for example, narrow down the directions in which the target A and the target B exist based on the power of the processing result of the FFT processing of the beat signal, and then derive the directions of the target A and the target B. You may. Even with such a configuration, the radar device 1 can reduce the processing load required for deriving the direction of the target.

Further effects and variations can be easily derived by those skilled in the art. For this reason, the broader aspects of the invention are not limited to the particular details and representative embodiments described and described above. Thus, various modifications can be made without departing from the spirit or scope of the overall concept of the invention as defined by the appended claims and their equivalents.

1 Radar device 2 Transmitter 4 Transmitter antenna 5 Receiver antenna 6 Receiver 7 Signal processing device 21 Signal generator 22 Oscillator 61 Mixer 62 A / D converter 71 Transmission control unit 72 Detection unit 73 Storage unit 74 Mode vector information 81 FFT unit 82 Peak extraction unit 83 Direction calculation unit 84 Distance relative velocity calculation unit

Claims (4)

A storage unit that stores information in which a mode vector created for each combination of directions in which a plurality of targets can exist simultaneously within a range of directions in which the target can be detected and the combination of the directions are associated with each other.
The transmitter that transmits the transmitted wave and
A receiving unit that receives the reflected wave reflected by the target with a plurality of receiving antennas.
The angle spectrum indicating the direction of the target is sequentially calculated based on the reflected wave received by the plurality of receiving antennas and the mode vector, and the combination of the directions associated with the mode vector having the highest angle spectrum is obtained. It is equipped with a derivation unit that derives as a combination of the directions of the targets that exist at the same time .
The mode vector is the sum of the mode vectors for each of the plurality of targets, and the mode vector for each of the plurality of targets corresponds to the phase of the reflected wave received by the plurality of receiving antennas. radar apparatus, characterized in that. The mode vector is
The radar device according to claim 1, wherein the radar device is created for each difference in the angle spectrum of each target that may exist at the same time. The storage unit is
Further memorize the information associated with the single direction mode vector created for each single direction in which the target can exist within the range of the direction in which the target can be detected and the single direction.
The derivation unit is
The angle spectrum of a single target is sequentially calculated based on the reflected wave and the unidirectional mode vector, and the combination of the directions based on the azimuth associated with the unidirectional mode vector having the highest angle spectrum. The radar device according to claim 1 or 2, wherein the mode vector to be adopted for deriving the above-mentioned mode vector is selected. A process of storing mode vector information in which a mode vector created for each combination of directions in which a plurality of targets can exist simultaneously within a range of directions in which a target can be detected and a combination of the directions are associated with each other, and a process of storing the mode vector information.
The process of transmitting the transmitted wave and
The process of receiving the reflected wave reflected by the target with a plurality of receiving antennas, and the process of receiving the transmitted wave with a plurality of receiving antennas.
The angle spectrum indicating the direction of the target is sequentially calculated based on the reflected wave received by the plurality of receiving antennas and the mode vector information, and the combination of the directions associated with the mode vector having the highest angle spectrum. look including the step of deriving as orientation combinations of the target object that is present at the same time,
The mode vector is the sum of the mode vectors for each of the plurality of targets, and the mode vector for each of the plurality of targets corresponds to the phase of the reflected wave received by the plurality of receiving antennas. A target detection method characterized by being present.

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