WO2020049686A1

WO2020049686A1 - Target tracking device and target tracking method

Info

Publication number: WO2020049686A1
Application number: PCT/JP2018/033026
Authority: WO
Inventors: 洋志亀田; 洋介勝又; 立範小林
Original assignee: 三菱電機株式会社
Priority date: 2018-09-06
Filing date: 2018-09-06
Publication date: 2020-03-12

Abstract

Provided is a target tracking device (1) comprising a prediction unit (2), a combination decision unit (3), a smoothing unit (4), and a determination unit (5). With respect to the smoothing unit (4), which is a tracking filter, a target distance contained in a detected signal and Doppler velocity are set as initial smoothing values.

Description

Target tracking device and target tracking method

The present invention relates to a target tracking device and a target tracking method for tracking a target.

For example, Patent Literature 1 describes a target tracking device that predicts the motion of a target based on a target state vector and a target motion model formed of a target position and a speed vector in a north reference rectangular coordinate system. ing. The motion prediction of the target is such that when a reflected signal of a radio wave transmitted from the radar reflected by the target is received by the radar, a predicted value of the target Doppler frequency is calculated based on the received signal, and the newly obtained detection is performed. The target is tracked based on the correlation between the signal and the predicted value.

算出 The calculation of the predicted value of the target Doppler frequency requires a smoothed value of the detection signal calculated by the tracking filter. When the tracking filter processes a signal in the north reference rectangular coordinate system, the tracking filter includes a target velocity vector determined based on a change in target position included in detection signals obtained at two different observation times. Is set as the initial smoothed value.

JP-A-2014-153088

In the target tracking device described in Patent Literature 1, a target velocity vector determined from a target position change of a detection signal obtained at two different observation times is set as an initial smoothed value in the tracking filter. There was a problem that tracking of the target could not be established.

The present invention has been made to solve the above problems, and has as its object to provide a target tracking device and a target tracking method that can reduce the time until the tracking of a target is established.

目標 The target tracking device according to the present invention includes a prediction unit, a combination determination unit, a smoothing unit, and a determination unit. The prediction unit calculates predicted values of the target distance and the Doppler velocity based on the smoothed values of the target distance and the Doppler velocity. The combination determination unit is configured to determine, based on the predicted value calculated by the prediction unit, a detection signal including a target distance and a Doppler velocity obtained by performing signal processing on the radar reception signal and a target obtained by the detection signal. Determine the combination. The smoothing unit sets the target distance and the Doppler velocity included in the detection signal having no correlation with the existing target to an initial smoothed value, and the target distance and the Doppler velocity included in the detection signal whose combination is determined by the combination determination unit. Is calculated. The determination unit determines a target signal to be tracked from a sequence of detection signals having a time-series correlation.

According to the present invention, the target distance and the Doppler velocity included in the detection signal having no correlation with the existing target with respect to the smoothing unit are set to the initial smoothed value. There is no need to set an initial smoothing value using the obtained detection signal. As a result, it is possible to shorten the time until the tracking of the target is established by the time for obtaining these detection signals.

FIG. 2 is a block diagram illustrating a configuration of a target tracking device according to Embodiment 1. FIG. 3 is a diagram showing a flow of signal processing of a received signal of a radar handled by the target tracking device according to the first embodiment. FIG. 3 is a diagram illustrating a spectrum space represented by a range and a Doppler velocity. FIG. 4A is a block diagram illustrating a configuration of hardware that implements the function of the target tracking device according to the first embodiment. FIG. 4B is a block diagram illustrating a configuration of hardware that executes software for realizing the function of the target tracking device according to Embodiment 1. 5 is a flowchart illustrating a target tracking method according to the first embodiment. FIG. 3 is a diagram illustrating an outline of angle measurement processing according to the first embodiment. FIG. 9 is a block diagram illustrating a configuration of a target tracking device according to a second embodiment. 9 is a flowchart illustrating a target tracking method according to the second embodiment. It is an image figure showing the outline of the gate used for determining the combination of a detection signal and a temporary target.

Embodiment 1 FIG.
FIG. 1 is a block diagram illustrating a configuration of a target tracking device 1 according to the first embodiment. FIG. 2 is a diagram illustrating a flow of signal processing of a received signal of a radar handled by the target tracking device 1. FIG. 3 is a diagram illustrating a spectrum space represented by a range and a Doppler velocity. The target tracking device 1 tracks a target based on a detection signal obtained by performing signal processing on a radar reception signal as shown in FIG. The detection signal has the coordinates of the range-Doppler velocity spectral space shown in FIG. 3, represented by the range and the Doppler velocity.

In FIG. 2, the radar receives, for example, a reflected signal of a transmitted radio wave reflected by a target by using n element antennas. n is a positive natural number of 2 or more. The signal processing device provided in the radar performs a first-order FFT (fast Fourier transform) on the reception signals from the reception CH (1) to the reception CH (n) for each element antenna. In the primary FFT processing, data indicating the target distance is obtained by performing an FFT on the received signal by the signal processing device.

In DBF (Digital Beam Forming), the signal processing apparatus performs DBF processing on data indicating a target distance from the reception CH (1) to the reception CH (n), thereby receiving beams (1) having different directions from each other. From the reception beam (m). m is a positive natural number of 2 or more. In the second-order FFT processing, the signal processor performs FFT on signals from the reception beam (1) to the reception beam (m), thereby obtaining a Doppler velocity for each target distance.

In the CFAR (Constant False Alarm Rate) process, the signal processing device automatically detects a signal having a signal strength exceeding a certain threshold from the signal processed up to the second FFT. The automatically detected detection signal includes, in addition to the target distance and the Doppler velocity, a reception beam number for identifying the reception beam of the reception signal from which the detection signal was obtained, and the signal strength of the reception signal. The reception beam number is an identification number assigned to each reception beam.

The detection signals from the reception beam (1) to the reception beam (m) are input to the target tracking device 1 from the signal processing device. The target tracking device 1 performs a target tracking process and an angle measurement process using the detection signal. The signal indicating the track of the tracking target calculated by the target tracking device 1 is, for example, converted into a signal in the north reference rectangular coordinate system and presented to the user.

As described above, the target tracking device 1 does not convert the detection signal into a signal of the north reference rectangular coordinate system unlike the conventional target tracking device in the target tracking process and the angle measurement process, and thus the initial smoothing of the target speed is performed. There is no need for a two-sample detection signal for calculating the value. Thus, the target tracking device 1 can reduce the time required for the target tracking to be established by the time for detecting these detection signals.

In the conventional target tracking device described in the following reference, the initial value of the target speed vector is determined based on the target position vector and the speed change included in the target detection signal obtained by one observation. Then, it is set as the initial value of the tracking filter. However, it is necessary to observe a detection signal including a target speed change at two or more receiving stations distributed.
On the other hand, since the target tracking device 1 uses the Doppler speed included in the detection signal as the initial smoothed value of the target speed, the target tracking device 1 can track the target based on the detection signal obtained by one receiving station. It is possible.
(Reference) M. Jabbarian, “Target Tracking in Pulse-Doppler MIMO Radar by Extended Kalman Filter Using Velocity Vector,” 20th Iranian Conference on Electrical Engineering, (ICEE2012), May 15-17, 2012, Tehran, Iran.

In the following description, the targets in the first embodiment include a provisional target and a tracking target. The temporary target is a candidate for a tracking target that has not been determined by the determination unit 5 to be a tracking target, and is a sequence of detection signals automatically detected by the CFAR. The detection signal sequence is a detection signal sequence having a time-series correlation. The tracking target is a target of the tracking target for which the tracking has been established, and is a sequence of detection signals corresponding to the candidates determined to be the tracking targets by the determination unit 5 among the candidates of the tracking targets that are temporary targets. The state in which tracking is established is a state in which the existence of a tracking target is determined in a track represented by a sequence of detection signals having a time-series correlation. Therefore, tracking is not established with the provisional target.

The target tracking device 1 includes a predicting unit 2, a combination determining unit 3, a smoothing unit 4, a determining unit 5, an angle measuring unit 6, and an angle smoothing unit 7, as shown in FIG. The prediction unit 2 includes a provisional target prediction unit 21 and a tracking target prediction unit 22. Although FIG. 1 shows a configuration in which the target tracking device 1 includes the angle measuring unit 6 and the angle smoothing unit 7, the angle measuring unit 6 and the angle smoothing unit 7 are provided separately from the target tracking device 1. It may be a component included in the device. For example, the signal processing device provided separately from the target tracking device 1 may include the angle measuring unit 6 and the angle smoothing unit 7.

The prediction unit 2 calculates a predicted value of the distance and the Doppler velocity for the target based on the smoothed values of the target distance and the Doppler velocity. The provisional target predicting unit 21 calculates predicted values of the provisional target distance and the Doppler velocity based on the smoothed values of the provisional target distance and the Doppler velocity. The tracking target predicting unit 22 calculates a predicted value of the tracking target distance and the Doppler velocity based on the smoothed values of the tracking target distance and the Doppler velocity.

The combination determining unit 3 determines a combination of the tentative target and the detection signal and a combination of the tracking target and the detection signal based on the predicted value calculated by the prediction unit 2.
For example, the combination determination unit 3 sets a gate for the provisional target based on the prediction value of the distance and the Doppler velocity of the provisional target calculated by the provisional target prediction unit 21 and the error of the prediction value. Subsequently, the combination determining unit 3 determines whether or not the detection signal obtained by performing signal processing on the radar reception signal is included in the gate, and determines whether the detection signal included in the gate and the provisional target are included. Determine the combination.

The combination determining unit 3 determines the tracking target based on the distance and Doppler velocity predicted value of the tracking target calculated by the tracking target predicting unit 22, the predicted value of the center angle of the received beam, and an error between these predicted values. Set the gate. Subsequently, the combination determination unit 3 determines whether or not the detection signal obtained by performing signal processing on the radar reception signal is included in the gate, and determines whether the detection signal included in the gate and the tracking target are included. Determine the combination.

If the detection signal obtained by performing signal processing on the radar received signal is not included in any of the provisional target gate and the tracking target gate, the detection signal is a detection signal having no correlation with the existing target. The combination determining unit 3 sets the target distance and the Doppler velocity included in the detection signal in the smoothing unit 4 as an initial smoothed value.

When starting the smoothing processing of the detection signal, the smoothing unit 4 sets the target distance and the Doppler velocity included in the detection signal having no correlation with the existing target to the initial smoothed values, and the combination determination unit 3 determines the combination. A smoothed value of the target distance and the Doppler velocity included in the detected signal is calculated. For example, when the initial smoothing value is set, the smoothing unit 4 executes a smoothing process according to the process of the Kalman filter.

The determination unit 5 determines a sequence based on a tracking target from a sequence of detection signals having a time-series correlation. For example, the determination unit 5 determines, among a series of detection signals determined to be combined with the tentative target, a series of detection signals whose number of times of correlation with the detected signal determined to be combined with the tracking target exceeds a certain threshold value. Is determined to be based on the tracking target.

The angle measurement unit 6 performs angle measurement processing for each tracking target using the sequence of the detection signals determined by the determination unit 5 to be based on the tracking target. For example, the angle measurement unit 6 calculates an angle measurement value using a sequence of the detection signal based on the tracking target and accumulated data of the amplitude value of the reception beam related to the sequence of the detection signal. The angle measurement value is, for example, the azimuth of the tracking target.

Note that the amplitude value of the reception beam is adjacent to the reception beam corresponding to the detection signal determined to be correlated with the tracking target and has the same coordinates (in the spectrum space of the range-Doppler velocity) as the detection signal. (A distance and a Doppler velocity).

角 Furthermore, the angle measurement unit 6 calculates an initial value of an angular velocity of an azimuth angle (hereinafter, referred to as an azimuth angular velocity) that changes with movement of the tracking target. The angle measurement value and the initial value of the azimuth angular velocity calculated by the angle measurement unit 6 are output to the angle smoothing unit 7.

The angle smoothing unit 7 calculates a smoothed value obtained by smoothing an angle measurement error of the angle measurement value based on the angle measurement value input from the angle measurement unit 6 and the initial value of the azimuth angular velocity. For example, when the initial value of the azimuth angular velocity is set, the angle smoothing unit 7 performs a smoothing process on the angle measurement value input from the angle measurement unit 6 according to the Kalman filter process. The smoothed value of the angle measurement value calculated by the angle smoothing unit 7 is output to the tracking target prediction unit 22.

The tracking target predicting unit 22 predicts the distance of the tracking target and the Doppler velocity based on the smoothed value of the detection signal calculated by the smoothing unit 4 and the smoothed value of the angle measurement value calculated by the angle smoothing unit 7. , And a predicted value of the center angle of the reception beam corresponding to the detection signal of the tracking target is calculated. The predicted value of the distance and Doppler velocity of the tracking target and the predicted value of the center angle of the received beam are output from the tracking target predicting unit 22 to the combination determining unit 3.

Next, a hardware configuration for realizing the function of the target tracking device 1 will be described.
The functions of the prediction unit 2, the combination determination unit 3, the smoothing unit 4, the determination unit 5, the angle measurement unit 6, and the angle smoothing unit 7 in the target tracking device 1 are realized by a processing circuit. That is, the target tracking device 1 includes a processing circuit for executing processing from step ST101 to step ST108 described later with reference to FIG. The processing circuit may be dedicated hardware, or may be a CPU (Central Processing Unit) that executes a program stored in the memory.

FIG. 4A is a block diagram showing a configuration of hardware for realizing the function of the target tracking device 1. FIG. 4B is a block diagram illustrating a configuration of hardware that executes software for realizing the function of the target tracking device 1. 4A and 4B, an interface 100 is an interface that relays signals exchanged with the radar that performs the signal processing illustrated in FIG.

When the processing circuit is the processing circuit 101 of dedicated hardware illustrated in FIG. 4A, the processing circuit 101 may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, or an ASIC (Application \ Specific \ Integrated). (Circuit), FPGA (Field-Programmable Gate Array), or a combination thereof. The functions of the prediction unit 2, the combination determination unit 3, the smoothing unit 4, the determination unit 5, the angle measurement unit 6, and the angle smoothing unit 7 in the target tracking device 1 may be realized by separate processing circuits. May be realized by one processing circuit.

When the processing circuit is the processor 102 illustrated in FIG. 4B, the functions of the prediction unit 2, the combination determination unit 3, the smoothing unit 4, the determination unit 5, the angle measurement unit 6, and the angle smoothing unit 7 in the target tracking device 1 , Software, firmware or a combination of software and firmware. The software or firmware is described as a program and stored in the memory 103.

The processor 102 reads out and executes the program stored in the memory 103 to thereby execute the prediction unit 2, the combination determination unit 3, the smoothing unit 4, the determination unit 5, the angle measurement unit 6, and the angle smoothing unit in the target tracking device 1. 7 functions are realized. That is, the target tracking device 1 includes a memory 103 for storing a program that, when executed by the processor 102, results in steps ST101 to ST108 shown in FIG.

These programs cause the computer to execute the procedures or methods of the prediction unit 2, the combination determination unit 3, the smoothing unit 4, the determination unit 5, the angle measurement unit 6, and the angle smoothing unit 7. The memory 103 is a computer-readable storage medium storing a program for causing a computer to function as the prediction unit 2, the combination determination unit 3, the smoothing unit 4, the determination unit 5, the angle measurement unit 6, and the angle smoothing unit 7. Is also good.

The memory 103 includes, for example, a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable Read Only Memory), a nonvolatile semiconductor memory such as an EEPROM (Electrically-EROM) or the like. A magnetic disk, a flexible disk, an optical disk, a compact disk, a mini disk, a DVD, and the like are applicable.

Some of the functions of the prediction unit 2, the combination determination unit 3, the smoothing unit 4, the determination unit 5, the angle measurement unit 6, and the angle smoothing unit 7 are partially realized by dedicated hardware, and partly realized by software or firmware. Is also good. For example, the prediction unit 2, the combination determination unit 3, the smoothing unit 4, and the determination unit 5 realize their functions by a processing circuit 101 that is dedicated hardware, and the angle measurement unit 6 and the angle smoothing unit 7 A function is realized by reading and executing the program stored in the. As described above, the processing circuit can realize the above functions by hardware, software, firmware, or a combination thereof.

Next, the operation will be described.
FIG. 5 is a flowchart illustrating the target tracking method according to the first embodiment.
In the following description, are estimated by the smoothing unit 4 is tracking filter, the target state vector at the measurement time k and x _k. The state vector x _k is a vector including the smoothed value rk of the distance from the radar to the target up to the observation time _k and the smoothed value V _k of the target Doppler velocity as elements as shown in the following equation (1). Let the observation value vector of the detection signal at the observation time k be z _k . Observation vector _{z k,} as shown in the following formula (2), in the observation time k, a distance _{r 0} from the radar to the _{target, k,} the Doppler velocity _{V 0} which _{target, k,} of the receive beam amplitude values _{v m, k} , And the reception beam number b _{m, k} as an element. In the following equations (1) and (2), T represents transposition of a matrix.
x _k = [r _k V _k ] ^T (1)
z _k = [r _{0, k} V _{0, k} v _{m, k} b _{m, k} ] ^T (2)

(4) The combination determination unit 3 inputs a detection signal from the signal processing device (step ST101). The detection signal includes a target distance and a Doppler velocity, a reception beam number, and a signal strength. The prediction unit 2 calculates a predicted value of the distance and the Doppler velocity of the provisional target or the tracking target by performing a prediction process based on the smoothed value of the detection signal calculated by the smoothing unit 4 (step ST102). For example, the prediction unit 2 calculates a time difference Δt between the acquisition time at which the combination determination unit 3 acquires the detection signal from the signal processing device and the smoothed time of the detection signal calculated by the smoothing unit 4 in step ST104. A predicted value of the target distance and the Doppler velocity at the time of acquisition of the detection signal is calculated.

In the process of calculating the predicted value, processing having different contents is performed depending on whether the target is a provisional target or a tracking target. For example, for the tentative target prediction unit 21 uses a smoothing value V _k smoothed value r _k and the Doppler velocity of the distance of the calculated target by the smoothing unit 4 at step ST 104, according to the following formula (3), the temporary target calculating a predicted value _{r k + 1} and the predicted values _{V k + 1} of the Doppler velocity of the distance. The smoothed value used in the process of calculating the predicted value is a smoothed value of a detection signal including the same reception beam number.

Using the smoothed value of the detection signal calculated by the smoothing unit 4 in step ST104, the tracking target predicting unit 22 calculates a predicted value of the tracking target distance and the Doppler velocity according to the above equation (3). Further, the tracking target predicting unit 22 calculates a predicted value of the center angle of the received beam according to the following equation (4) using the angle smoothed value calculated by the angle smoothing unit 7 in step ST107. In the following equation (4), θ _k is the azimuth (angle measurement value) at the observation time k. dθ _k is an initial smoothed value of the azimuth angular velocity in which the angle measurement error up to the observation time k has been smoothed, and is calculated by the angle smoothing unit 7 in step ST107. θ _{k + 1} is the predicted value of the azimuth angle at the observation time k + 1 one observation time after the observation time k, and dθ _{k + 1} is the predicted value of the azimuth angular velocity at the observation time k + 1. The predicted value of the center angle of the reception beam is determined by the predicted value θ _{k + 1} and the predicted value dθ _{k + 1} .

Note that at the stage where the process first proceeds to step ST102, the processes after step ST103 are not executed, and the prediction unit 2 determines the smoothed value of the detection signal calculated by the smoothing unit 4 in step ST104 and the angle in step ST107. The angle smoothing value calculated by the smoothing unit 7 cannot be obtained. At this time, the prediction unit 2 does not perform the above-described prediction processing, and the processing of the target tracking device 1 proceeds to step ST103.

The combination determination unit 3 obtains a detection signal and the detection signal using the predicted value of the distance and the Doppler velocity of the provisional target or the tracking target calculated in step ST102 and the detection signal input in step ST101. A combination with the provisional target or the tracking target is determined (step ST103). In the combination determination process, different gates are set depending on whether the target is a provisional target or a tracking target.

For example, the combination determination unit 3 sets a gate in the range-Doppler velocity spectrum space based on the predicted values of the distance and the Doppler velocity of the provisional target calculated by the provisional target prediction unit 21 and an error between these predicted values. Set. Subsequently, the combination determination unit 3 determines, among the detection signals obtained by performing signal processing on the radar reception signal, the detection signal included in the gate as having a correlation with the provisional target detection signal. The detection signal and the provisional target are combined.
The detection signals used in the combination determination processing are detection signals including the same reception beam number. That is, the combination is determined for each identical reception beam number.

Further, the combination determination unit 3 calculates the distance and the Doppler velocity of the tracking target calculated by the tracking target prediction unit 22, the predicted value of the center angle of the received beam, and an error between these predicted values. Set a gate in the range-Doppler velocity spectral space. Subsequently, the combination determination unit 3 determines that the detection signal included in the gate has a correlation with the detection signal of the tracking target, and combines the detection signal with the tracking target. The combination determining unit 3 determines a combination of the detection signal corresponding to the predicted reception beam direction with the tracking target.

The combination determination unit 3 sets the value of the detection signal, which is not included in any of the two types of gates, from the detection signal to the smoothing unit 4 as an initial smoothed value. That is, in the smoothing unit 4, the target distance and the Doppler velocity included in the detection signal having no correlation with the provisional target and the tracking target detected up to the current observation time are set as the initial smoothed values.

The combination determination unit 3 specifies a detection signal closest to the predicted value of the distance and the Doppler speed of the provisional target or the tracking target from the target distance and the Doppler speed included in the detection signal, and specifies the detection signal and the provisional target or the tracking target. It may be combined with a goal. The combination determining unit 3 compares the distance and the Doppler speed of the provisional target or the tracking target included in all the detection signals included in the gate with the target distance and the Doppler speed on a brute force basis, and the two are closest. The detection signal and the provisional target or the tracking target may be combined.

Furthermore, the combination determining unit 3 sets the amplitude value of the reception beam for the information indicating the combination of the detection signal and the target. The amplitude value of the reception beam is adjacent to the reception beam corresponding to the detection signal determined to be correlated with the tracking target and has the same coordinates (distance and Doppler) as the detection signal in the spectrum space of the range-Doppler velocity. (Velocity) of the received signal of the detection signal having the velocity.

The smoothing unit 4 calculates a smoothed value of the detection signal by executing a smoothing process based on the combination of the target and the detection signal determined by the combination determination unit 3 in step ST103 (step ST104). The smoothing unit 4 is set with an initial smoothed value according to the following equation (5). x ₁ is the initial smoothed value of the target state vector, r _{0, 1} is the distance of a target included in the tentative target and tracking target and the correlation is no detection signal, which is the initial smoothed value of the distance of the target. V _0,1 is the target Doppler velocity included in the detection signal having no correlation with the provisional target and the tracking target, and is an initial smoothed value of the target Doppler velocity.
x ₁ = [r _0,1 V _0,1 ] ^T (5)

After the initial smoothing value is set, the smoothing unit 4 performs the smoothing process according to, for example, the process of the Kalman filter. For example, the smoothing unit 4 receives information on a combination of the detection signal and the provisional target or the tracking target from the combination determination unit 3. Information on the combination of the detection signal and the provisional target or the tracking target includes correlation determination information. The correlation determination information is information indicating a result of determining a correlation between the detection signal and the provisional target or the tracking target.

The smoothing unit 4 sequentially specifies detection signals having a correlation with the provisional target or the tracking target based on the correlation determination information. The smoothing unit 4 performs a smoothing process using the specified detection signal sequence and the initial smoothed value, and calculates a smoothed value in which errors in the distance and the Doppler velocity of the tentative target or the tracking target are smoothed. The correlation determination information includes the degree to which the correlation between the detection signal determined by the combination determination unit 3 and the temporary target or the tracking target has been established. The degree to which the correlation is established is, for example, the number of times the detection signal is included in the gate of the provisional target or the tracking target set by the combination determination unit 3 or the hypothesis about the combination of the detection signal and the provisional target or the tracking target. Is the degree of reliability.

{Furthermore, the smoothing unit 4 stores the amplitude value of the received beam in the storage unit for each detection signal for which the combination with the target is determined by the combination determination unit 3. This storage unit is a storage unit in which information can be written by the smoothing unit 4 and information can be read by the angle measurement unit 6. Further, the amplitude value of the received beam is adjacent to the received beam corresponding to the detected signal determined to be correlated with the tracking target, and has the same coordinates (distance) as the detected signal in the spectrum space of the range-Doppler velocity. And the Doppler velocity) of the detection signal having the same amplitude.

Next, the determination unit 5 determines, from the sequence of detection signals having a time-series correlation, one based on the tracking target (step ST105). For example, based on the correlation determination information input from the smoothing unit 4, the determination unit 5 determines, from the sequence of the detection signals combined with the tentative target by the combination determination unit 3, the correlation between the detection signal combined with the tracking target and the correlation. Judge something. The provisional target having a correlation with the sequence of the detection signal combined with the tracking target is determined as the tracking target for which the tracking has been established.

The angle measurement unit 6 performs angle measurement processing for each tracking target by using the sequence of the detection signals determined to be correlated with the tracking target by the determination unit 5 (step ST106). FIG. 6 is a diagram illustrating an outline of the angle measurement processing. In FIG. 6, a range-Doppler velocity spectrum space 200a includes a detection signal 201a of a reception beam (k) combined with a tracking target. The range-Doppler velocity spectrum space 200b includes a detection signal 201b corresponding to the reception beam (k + 1) adjacent to the reception beam (k) and having the same coordinates as the detection signal 201a.

The angle measuring unit 6 calculates a difference signal Δ between the amplitude value of the reception beam (k) of the detection signal 201a and the amplitude value of the reception beam (k + 1) of the detection signal 201b, and further calculates the sum signal Σ of both. . Next, the angle measurement unit 6 calculates the angle measurement value θ _k of the tracking target according to the following equation (6). The angle measurement value θ _k is the azimuth of the tracking target. The angle measurement coefficient k _dsc is a slope of the amplitude angle characteristic when the difference signal Δ is normalized by the sum signal Σ. θ ₀ is the center angle of the reception beam (k). Δ / Σ is a discrete curve.
θ _k = sin ⁻¹ {k _dsc (Δ / Σ) + sin θ ₀ } (6)

Further, the angle measurement unit 6 uses the accumulated data of the angle measurement values corresponding to the series of the detection signals for which the combination with the tracking target has been determined by the combination determination unit 3 before the current observation time, using the following equation (7). , The initial value dθ _k of the azimuth angular velocity of the tracking target is calculated. The angle measurement value θ _k−1 is the angle measurement value of the tracking target at the observation time k−1 one observation time before the observation time k, and Δt is obtained between the observation time k and the observation time k−1. This is the time difference between the detected detection signal and the smoothed time.
dθ _k = (θ _k −θ _k−1 ) / Δt (7)

Next, the angle smoothing unit 7 smoothes the angle measurement value calculated in the angle measurement processing of the angle measurement unit 6 (step ST107). For example, after the initial value dθ _k of the azimuth angular velocity is set, the angle smoothing unit 7 performs a smoothing process on the angle measurement value θ _k input from the angle measurement unit 6 according to the process of the Kalman filter. The smoothed value of the angle measurement value calculated by the angle smoothing unit 7 is output to the tracking target prediction unit 22. The tracking target predicting unit 22 calculates a predicted value of the center angle of the reception beam corresponding to the tracking target based on the smoothed value calculated by the angle smoothing unit 7.

Next, the combination determination unit 3 checks whether the target tracking processing has been completed (step ST108). If the process has ended (step ST108; YES), a series of processes shown in FIG. 5 ends. If the processing has not ended (step ST108; NO), the process returns to step ST101, and a series of processing from step ST101 is repeated.

As described above, in the target tracking device 1 according to the first embodiment, the target distance and the Doppler velocity included in the detection signal having no correlation with the existing target are set in the smoothing unit 4 as initial smoothed values. For this reason, the target tracking device 1 does not need to set the initial smoothed value using the detection signals obtained at two different observation times as in the conventional target tracking device, and only needs to obtain the detection signal of two samples. The time until the tracking of the target is established can be shortened.

In the conventional target tracking device, the angle measurement process is performed before the tracking target is determined. However, the angle measurement unit 6 uses a sequence of the detection signals determined by the determination unit 5 to be correlated with the tracking target. The angle measurement process is performed for each tracking target. Since the target for which the angle measurement value should be calculated is limited to the tracking target, the calculation amount of the angle measurement processing can be reduced, and the processing time can be shortened.

Furthermore, in the target tracking device 1 according to the first embodiment, the angle smoothing unit 7 smoothes the angle measurement value calculated by the angle measurement processing of the angle measurement unit 6. The tracking target predicting unit 22 calculates the distance of the tracking target based on the distance of the tracking target and the smoothed value of the Doppler velocity calculated by the smoothing unit 4 and the smoothed value of the angle measurement value calculated by the angle smoothing unit 7. Further, a predicted value of the Doppler velocity and a predicted value of the center angle of the reception beam corresponding to the tracking target are calculated. This makes it possible to predict the receiving beam direction from which the tracking target detection signal is obtained.

Embodiment 2 FIG.
FIG. 7 is a block diagram showing a configuration of a target tracking device 1A according to Embodiment 2. The same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted. As shown in FIG. 1, the target tracking device 1A includes a prediction unit 2, a combination determination unit 3A, a smoothing unit 4, a determination unit 5, an angle measurement unit 6, and an angle smoothing unit 7. The prediction unit 2 includes a provisional target prediction unit 21 and a tracking target prediction unit 22.

The combination determining unit 3A determines a combination of the detection signal and the provisional target according to which of the first gate and the second gate has the detection signal in the range-Doppler velocity spectrum space. decide. The first gate is a gate in which the predicted value of the distance of the temporary target is set at the center of the gate. The second gate is a gate whose range in the range direction is set at a speed exceeding the observable speed range of the radar.

As shown in FIGS. 4A and 4B, the functions of the prediction unit 2, the combination determination unit 3A, the smoothing unit 4, the determination unit 5, the angle measurement unit 6, and the angle smoothing unit 7 are realized by dedicated hardware. It may be realized by software or firmware. Some of the functions of the prediction unit 2, the combination determination unit 3A, the smoothing unit 4, the determination unit 5, the angle measurement unit 6, and the angle smoothing unit 7 are partially realized by dedicated hardware, and partly realized by software or firmware. May be.
As described above, the processing circuit can realize the above functions by hardware, software, firmware, or a combination thereof.

Next, the operation will be described.
FIG. 8 is a flowchart illustrating a target tracking method according to the second embodiment. Steps ST101, ST102, and steps ST104 to ST108 shown in FIG. 8 are the same as those in FIG.
The combination determination unit 3A determines a combination of the tentative target and the detection signal and a combination of the tracking target and the detection signal based on the prediction value calculated by the prediction unit 2 (step ST103A). FIG. 9 is an image diagram showing an outline of a gate used for determining a combination of a detection signal and a provisional target. The combination determining unit 3A sets a first gate 301 and a second gate 302 as shown in FIG. 9 when determining the combination of the detection signal and the provisional target.

The first gate 301 is a gate whose gate center is a predicted value of the distance from the radar to the temporary target in the range-Doppler velocity spectrum space. The detection signal 300 including the predicted value of the distance to the temporary target is included in the first gate 301. The second gate 302 is a gate in which the range in the range direction is set at a speed exceeding the observable speed range of the radar in the spectrum space of the range-Doppler speed, and the center of the gate is a predicted value of the distance of the temporary target. When the maximum moving speed of the target is V _max and the time difference between the target observation time k and the smoothed time of the target detection signal obtained up to the observation time k−1 is Δt, the second gate 302 Is defined by V _max Δt as shown in FIG.

The combination determination unit 3A sets the detection signal included in the first gate 301 and the detection signal included in the second gate 302 as a combination candidate with the provisional target. The second gate 302 includes a detection signal in which the target moving speed v satisfies the relationship shown in the following equation (8) with respect to the observable speed range of the radar. In the following equation (8), the right side indicates the observable speed range of the radar, the transmission wavelength of the radio wave by the radar is λ, and _TPRI is the pulse repetition period of the radar.
v> λ / (4T _PRI ) (8)

Subsequently, the combination determination unit 3A determines a temporal change between the target distance r _k−1 ^(p) included in the detection signal in the second gate 302 and the predicted value r _k of the distance of the temporary target that is the gate center. The Doppler velocity V _k tilde is calculated according to the following equation (9) using the distance change rate of The combination determination unit 3A calculates the coordinates of the Doppler velocity V _k tilde calculated according to the following equation (9) in the spectrum space of the range-Doppler velocity and the target Doppler velocity included in the detection signal as a candidate for combination with the temporary target. the difference between V _k coordinates, if the predetermined value or less ε as shown in the following formula (10), combining the detection signal and the tentative target. In this way, one of the detection signal in the first gate 301 and the detection signal in the second gate 302 is combined with the provisional target. In the following equation (9), mod {} is a modulo operation function, and (r _k −r _k−1 ^(p) ) / Δt is a distance change rate.

As described above, in the target tracking device 1A according to the second embodiment, the combination determining unit 3A determines that the predicted value of the distance of the temporary target is set at the gate center in the spectral space represented by the range and the Doppler velocity. The detection signal and the tentative target are determined according to which of the one gate 301 and the second gate 302 whose range in the range direction is set at a speed exceeding the observable speed range of the radar. To determine the combination. By setting the second gate 302, it is possible to track a target moving at a speed exceeding the observable speed range of the radar.

Note that the present invention is not limited to the above embodiments, and within the scope of the present invention, each free combination of the embodiments or the modification of any of the constituent elements of the embodiments or the embodiments. In each of the above, arbitrary components can be omitted.

目標 The target tracking device according to the present invention can shorten the time until the tracking of the target is established, so that it can be used for a radar for observing a moving target such as a ship or an aircraft.

1, 1A target tracking device, 2 prediction unit, 3, 3A combination determination unit, 4 smoothing unit, 5 determination unit, 6 angle measurement unit, 7 angle smoothing unit, 21 temporary target prediction unit, 22 tracking target prediction unit, 100 interface, 101 processing circuit, 102 processor, 103 memory, 200a, 200b spectral space, 201a, 201b, 300 detection signal, 301 first gate, 302 second gate.

Claims

A prediction unit that calculates a predicted value of the target distance and the Doppler velocity based on the smoothed value of the target distance and the Doppler velocity;
Based on the prediction value calculated by the prediction unit, a combination of a detection signal including a target distance and a Doppler velocity obtained by signal processing of a radar reception signal and a target from which the detection signal is obtained is determined. A combination determining unit;
The target distance and the Doppler velocity included in the detection signal having no correlation with the existing target are set to the initial smoothed value, and the target distance and the Doppler velocity included in the detection signal whose combination is determined by the combination determination unit are determined. A smoothing unit for calculating a smoothed value;
A target tracking device, comprising: a determination unit that determines, based on a target to be tracked, a sequence of the detection signals having a correlation in a time series.
The method according to claim 1, further comprising: an angle measurement unit that performs an angle measurement process for each of the targets to be tracked using the sequence of the detection signals determined to be based on the target to be tracked by the determination unit. Target tracking device.
An angle smoothing unit that smoothes the angle measurement value calculated in the angle measurement processing of the angle measurement unit,
The prediction unit is configured to calculate the distance and the Doppler of the target to be tracked based on the smoothed value of the target distance and the Doppler velocity calculated by the smoothing unit and the smoothed value of the angle measurement value calculated by the angle smoothing unit. The target tracking device according to claim 2, wherein a predicted value of the speed and a predicted value of a center angle of the reception beam corresponding to the target to be tracked are calculated.
In the spectral space represented by the range and the Doppler velocity, the combination determiner includes a first gate in which the predicted value of the target distance is set at the center of the gate and a range direction range at a speed exceeding the observable speed range of the radar. The target tracking device according to claim 1, wherein a combination of the detection signal and the target is determined according to which of the second gates set with the detection signal has the detection signal. .
A prediction unit that calculates a predicted value of the target distance and the Doppler velocity based on the smoothed values of the target distance and the Doppler velocity;
The combination determining unit, based on the predicted value calculated by the prediction unit, a detection signal including the target distance and Doppler velocity obtained by signal processing of the radar received signal and the target from which the detection signal is obtained Determining a combination of
The smoothing unit sets the target distance and the Doppler velocity included in the detection signal having no correlation with the existing target to an initial smoothed value, and the target distance included in the detection signal whose combination is determined by the combination determination unit. Calculating a smoothed value of the Doppler velocity and
A determination unit for determining, from the sequence of the detection signals having a time-series correlation, the sequence based on the target to be tracked.