Target tracking device, target tracking method, and target tracking program

Abstract

To suppress false target tracking.SOLUTION: Provided is a target tracking device for detecting at a prescribed cycle timing and tracking a target in a detection object area. The target tracking device comprises: an acquisition unit for acquiring echo data that indicates a correspondence between a position in the detection object area and the level of a reflected electromagnetic wave having been transmitted via an antenna and reflected at the position; a tracking unit for performing tracking processing to track a target on the basis of the echo data; a calculation unit for extracting a reflector with which the level of the reflected wave is greater than or equal to a prescribed threshold on the basis of the echo data in sequence of time acquired at the timing and calculating an index value that indicates a sway of the reflector on the basis of the extraction result obtained at the timing; and a determination unit for determining whether or not the index value is greater than or equal to a threshold.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a target tracking device, a target tracking method, and a target tracking program. [Background technology]

[0002] Conventionally, a technique for suppressing clutter has been developed in a radar device having a function of tracking a target based on echo data. For example, Patent Document 1 (JP Patent Publication 2012-103197A) describes the following moving target compatible scan correlation method. That is, the moving target compatible scan correlation method includes a received image memory that stores video signals sequentially output from a signal receiving unit of a radar, ultrasonic, and optical camera device for each scan, a motion vector calculation unit that divides a plurality of scan images stored in the received image memory into small partition areas and calculates a motion vector of a target existing in the area, a target index calculation unit that calculates an index indicating the possibility that a target exists in the small partition area, a clutter level calculation unit that calculates a clutter level in the small partition area, a scan correlation processing unit that receives the outputs of the target index calculation unit, the motion vector calculation unit, and the clutter level calculation unit as inputs, and a display unit that displays the output of the scan correlation processing unit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-103197 A Summary of the Invention [Problem to be solved by the invention]

[0004] There is a need for a technology that goes beyond the technology described in Patent Document 1 and that is capable of suppressing erroneous tracking of a target.

[0005] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a target tracking device, a target tracking method, and a target tracking program that are capable of suppressing erroneous tracking of a target. [Means for solving the problem]

[0006] (1) In order to solve the above problem, a target tracking device according to one aspect of the present invention is a target tracking device that detects and tracks a target in a detection area at a predetermined periodic timing, and includes an acquisition unit that acquires echo data indicating a correspondence between a position in the detection area and a level of a reflected wave of an electromagnetic wave transmitted via an antenna and reflected at the position, a tracking unit that performs a tracking process to track the target based on the echo data, a calculation unit that extracts a reflector whose reflected wave level is equal to or greater than a predetermined value based on the time-series echo data acquired at the timing, and calculates an index value indicating the wobble of the reflector based on the extraction result obtained at the timing, and a determination unit that determines whether the index value is equal to or greater than a threshold value.

[0007] A reflector with large fluctuation may actually be a clutter source and may not be a target to be tracked. Therefore, by setting an index value indicating the fluctuation of the reflector, calculating this index value for the reflector, and judging whether it is equal to or greater than a threshold, it is possible to judge whether the reflector should be tracked or not.

[0008] (2) In the above (1), when the index value is less than the threshold value, the tracking unit may track the reflector as the target, and when the index value is equal to or greater than the threshold value, the tracking unit may exclude the reflector from the tracking target in the tracking process.

[0009] With this configuration, it is possible to track reflectors with small fluctuations as targets, while suppressing tracking of reflectors with large fluctuations such as clutter generation points, etc. Therefore, it is possible to suppress erroneous tracking of targets and reduce the processing load in the tracking process.

[0010] (3) In the above (2), the tracking unit may further perform a background tracking process to track the reflector excluded from the tracking target in the tracking process. Also, the tracking unit may perform a process to display a tracking result of the target tracked in the tracking process, but may not perform a process to display a tracking result of the reflector tracked in the background tracking process.

[0011] With this configuration, it is possible to display only reflectors with small fluctuations as the tracking result of the target to be displayed, while continuing to track reflectors with large fluctuations, such as clutter generation points.

[0012] (4) In the above (2), the tracking unit may further perform a background tracking process to track the reflector excluded from the tracking target in the tracking process. The tracking unit may also perform a process to display the tracking result of the target tracked in the tracking process and the tracking result of the reflector tracked in the background tracking process in different modes.

[0013] With this configuration, it is possible to distinguish between the tracking results of targets that are highly necessary to display and the tracking results of reflectors that fluctuate significantly, such as clutter generation points, and to display them separately.

[0014] (5) In the above (2), the acquisition unit may repeatedly acquire the echo data, and the tracking unit may exclude the reflector from a tracking target in the tracking process based on the first echo data and the echo data acquired after the first echo data when the index value indicating the wobble of the reflector detected based on the first echo data is equal to or greater than the threshold value.

[0015] With this configuration, it is not necessary to determine whether the index value is equal to or greater than the threshold value each time echo data is acquired, so that the processing load in the tracking process can be reduced.

[0016] (6) In the above (2), when the reflector is excluded from the tracking target in the tracking process, the tracking unit may perform an interpolation process to interpolate the position of the target with a predicted position of the target.

[0017] With this configuration, even if the target to be tracked cannot be detected based on echo data generated at a certain timing, it is possible to continue tracking the target.

[0018] (7) In any one of (1) to (6) above, the target tracking device may further include a determination unit that determines the threshold value based on a size of the reflector.

[0019] This configuration allows for a more appropriate determination as to whether or not a reflector should be a tracking target, etc. By employing this configuration, for example, it is possible to determine whether or not the index value is equal to or greater than a threshold value, using a threshold value that takes into account the magnitude of fluctuation that can be detected in echo data of a reflector, depending on the size of the reflector relative to the beam width output from the radar device.

[0020] (8) In the above (7), the determination unit may approximate the reflector with a polygonal reference region and determine the threshold value based on a size of the reference region.

[0021] With this configuration, the threshold value based on the size of the reflector can be determined by simple processing.

[0022] (9) In the above (7) or (8), the determination unit may approximate the reflector with a reference area surrounded by two straight lines extending in a distance direction from the antenna and two arcs extending in an azimuth direction with the antenna as a center, and determine the threshold value based on the size of the reference area.

[0023] With this configuration, the threshold value based on the size of the reflector can be determined by simple processing.

[0024] (10) In any one of (7) to (9) above, the determination unit may calculate a size of the reflector based on a distance between the antenna and the reflector.

[0025] With this configuration, the size of the reflector can be calculated more accurately taking into account the distance between the antenna and the reflector, thereby determining a more appropriate threshold value according to the actual size of the reflector.

[0026] (11) In any one of (7) to (10) above, the determination unit may determine the threshold value further based on AIS (Automatic Identification System) information.

[0027] With this configuration, a more appropriate threshold value can be determined based on the size of other ships indicated by AIS information, etc.

[0028] (12) In any one of (1) to (11) above, the calculation unit may calculate the index value based on an amount of change in a velocity vector of the reflector.

[0029] With this configuration, it is possible to make a more appropriate decision as to whether or not a reflector should be targeted for tracking, based on the amount of change in the velocity vector of the reflector.

[0030] (13) In any one of (1) to (11) above, the calculation unit may calculate the index value based on an amount of change in speed of the reflector.

[0031] With this configuration, it is possible to make a more appropriate decision as to whether or not the reflector should be treated as a tracking target, based on the amount of change in the speed of the reflector.

[0032] (14) In any one of (1) to (11) above, the calculation unit may calculate the index value based on an amount of change in a position of the reflector.

[0033] With this configuration, it is possible to make a more appropriate decision as to whether or not the reflector should be treated as a tracking target based on the amount of change in the position of the reflector.

[0034] (15) In order to solve the above-mentioned problems, a target tracking method according to a certain aspect of the present invention is a target tracking method in a target tracking device that detects and tracks a target in a detection target area at a predetermined periodic timing, the method acquiring echo data indicating a correspondence between a position in the detection target area and a level of a reflected wave obtained by reflecting an electromagnetic wave transmitted via an antenna at the position, performing a tracking process to track the target based on the echo data, extracting a reflector whose reflected wave level is equal to or higher than a predetermined value based on the time-series echo data acquired at the timing, calculating an index value indicating the wobble of the reflector based on the extraction result obtained at the timing, and determining whether the index value is equal to or higher than a threshold value.

[0035] A reflector with large fluctuation may actually be a clutter source and may not be a target to be tracked. Therefore, by setting an index value indicating the fluctuation of the reflector, calculating this index value for the reflector, and judging whether it is equal to or greater than a threshold, it is possible to determine whether the reflector should be tracked.

[0036] (16) In order to solve the above-mentioned problem, a target tracking program according to an aspect of the present invention is a target tracking program used in a target tracking device that detects and tracks a target in a detection area at a predetermined periodic timing, the program causing a computer to execute the following processes: a process of acquiring echo data indicating a correspondence between a position in the detection area and a level of a reflected wave of an electromagnetic wave transmitted via an antenna reflected at the position; a tracking process of tracking the target based on the time-series echo data acquired at the timing; a process of extracting a reflector whose reflected wave level is equal to or greater than a predetermined value based on the time-series echo data acquired at the timing, and calculating an index value indicating the wobble of the reflector based on the extraction result obtained at the timing; and a process of determining whether the index value is equal to or greater than a threshold value.

[0037] A reflector with large fluctuation may actually be a clutter source and may not be a target to be tracked. Therefore, by setting an index value indicating the fluctuation of the reflector, calculating this index value for the reflector, and judging whether it is equal to or greater than a threshold, it is possible to judge whether the reflector should be tracked or not. Effect of the Invention

[0038] According to the present invention, erroneous tracking of a target can be suppressed. [Brief description of the drawings]

[0039] [Figure 1] FIG. 1 is a diagram showing a configuration of a radar device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing an example of an echo image displayed by a display processing unit in the radar device according to the embodiment of the present invention. [Diagram 3] FIG. 3 is a diagram showing the trail of a target to be tracked by the radar device according to the embodiment of the invention and the trail of a clutter generation point. [Figure 4]FIG. 4 is a diagram illustrating an example of a method for calculating an index value by the display processing unit in the radar device according to the embodiment of the present invention. [Diagram 5] FIG. 5 is a diagram illustrating an example of a method for calculating an index value by the display processing unit in the radar device according to the embodiment of the present invention. [Figure 6] FIG. 6 is a diagram showing an example of a method for determining a threshold value by the display processing unit in the radar device according to the embodiment of the present invention. [Figure 7] FIG. 7 is a diagram showing an example of an echo image generated by a display processing unit in the radar device according to the embodiment of the present invention. [Figure 8] FIG. 8 is a diagram showing an example of an echo image generated by the display processing unit in the radar device according to the embodiment of the present invention. [Figure 9] FIG. 9 is a diagram showing another example of an echo image generated by the display processing unit in the radar device according to the embodiment of the present invention. [Figure 10] FIG. 10 is a diagram showing another example of an echo image generated by the display processing unit in the radar device according to the embodiment of the present invention. [Figure 11] FIG. 11 is a diagram showing another example of an echo image generated by the display processing unit in the radar device according to the embodiment of the present invention. [Figure 12] FIG. 12 is a diagram showing a configuration of a radar device according to a modified example of the embodiment of the present invention. In FIG. [Figure 13] FIG. 13 is a flowchart showing an example of an operation performed by the target tracking unit in the radar device according to the embodiment of the present invention when performing tracking processing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference characters and their description will not be repeated. In addition, at least some of the embodiments described below may be arbitrarily combined.

[0041] [Configuration and basic operation] FIG. 1 is a diagram showing a configuration of a radar device according to an embodiment of the present invention. Referring to FIG. 1, the radar device 201 includes a radar unit 20, a target tracking unit 101, and a display device 111. The target tracking unit 101 is an example of a target tracking device. The radar unit 20 includes an antenna 21, a transmission / reception unit 22, and a signal processing unit 23. The target tracking unit 101 includes an acquisition unit 11, a display processing unit 12, and a storage unit 13. The display processing unit 12 is an example of a tracking unit, an example of a calculation unit, an example of a decision unit, and an example of a determination unit. A part or all of the transmission / reception unit 22, the signal processing unit 23, the acquisition unit 11, and the display processing unit 12 are realized, for example, by a processing circuit including one or more processors. The storage unit 13 is, for example, a non-volatile memory included in the processing circuit.

[0042] The radar device 201 is mounted on the ship 1. The target tracking unit 101 detects and tracks a target S, such as another ship, in a detection target area Ta at a predetermined cycle and displays an echo image indicating the position of the target S on a display device 111. For example, the detection target area Ta is an area inside a circle of a predetermined size centered on the ship 1.

[0043] (Radar section) The radar unit 20 generates divided echo data EdD, which is echo data Ed indicating the correspondence between positions in a divided target area Da and echo levels at those positions, based on the reflected waves of the electromagnetic waves transmitted via the antenna 21. The divided target area Da is a sector-shaped region obtained by dividing the detection target area Ta into N portions along the azimuth angle direction. N is an integer equal to or greater than 2. The echo level at each position of the divided echo data EdD indicates the level of the reflected wave reflected at that position.

[0044] For example, the radar unit 20 generates the divided echo data EdD at a generation timing according to a predetermined generation cycle Cd.

[0045] More specifically, the transmitting / receiving unit 22 transmits electromagnetic waves via the antenna 21 during a sweep period T of a predetermined length, and receives reflected waves of the transmitted electromagnetic waves via the antenna 21. The transmitting / receiving unit 22 generates digital data Dd by digitally converting an echo signal indicating the received reflected wave. The transmitting / receiving unit 22 repeats the transmission of the electromagnetic waves and the generation of the digital data Dd while rotating the antenna 21 so that the azimuth angle of the transmission direction of the electromagnetic waves changes by a predetermined angle for each sweep period T. The transmitting / receiving unit 22 outputs the generated digital data Dd to the signal processing unit 23 every time it generates digital data Dd.

[0046] The signal processing unit 23 generates divided echo data EdD based on the multiple digital data Dd received from the transmitting / receiving unit 22. For example, the signal processing unit 23 generates divided echo data EdD in which echo levels at multiple positions in the division target area Da are binarized. More specifically, the signal processing unit 23 generates divided echo data EdD by converting the echo level values ​​at positions in the division target area Da where the echo level is equal to or greater than a predetermined threshold Tx to "1" and converting the echo level values ​​at positions where the echo level is less than the threshold Tx to "zero." The signal processing unit 23 transmits the generated divided echo data EdD to the target tracking unit 101 every time it generates divided echo data EdD.

[0047] (Target tracking unit) The acquisition unit 11 in the target tracking unit 101 acquires connected echo data EdC, which is echo data Ed indicating the correspondence between a position in a detection area Ta and an echo level at that position.

[0048] For example, the acquisition unit 11 generates concatenated echo data EdC at a generation timing Gs according to a scan period Cp that is N times the generation period Cd. More specifically, the acquisition unit 11 receives divided echo data EdD from the signal processing unit 23 and stores the received divided echo data EdD in the storage unit 13. Each time the number of divided echo data EdD stored in the storage unit 13 reaches N, the acquisition unit 11 acquires and concatenates the N pieces of divided echo data EdD from the storage unit 13 to generate concatenated echo data EdC. The acquisition unit 11 stores the generated concatenated echo data EdC in the storage unit 13.

[0049] The display processing unit 12 performs a tracking process to track the target S based on the echo data Ed. More specifically, when the acquisition unit 11 stores the linked echo data EdC in the storage unit 13, the display processing unit 12 identifies coordinates indicating the current position of the target S based on the linked echo data EdC. Then, the display processing unit 12 calculates a velocity vector V1 of the target S based on the identified coordinates indicating the current position of the target S, the coordinates of the target S in the past sweep period T, and the scan period Cp. The display processing unit 12 stores the calculated velocity vector V1 in the storage unit 13.

[0050] Fig. 2 is a diagram showing an example of an echo image displayed by a display processing unit in a radar device according to an embodiment of the present invention. Referring to Fig. 2, the display processing unit 12 performs processing to display a tracking result of a target S. More specifically, the display processing unit 12 generates an echo image showing a detection position P, which is the position of the target S detected in a detection target area Ta, and a velocity vector V1 of the target S, and performs processing to display the generated echo image on a display device 111.

[0051] For example, the display processing unit 12 updates the echo image displayed on the display device 111 each time the acquisition unit 11 stores the linked echo data EdC in the storage unit 13. More specifically, in the tracking process, the display processing unit 12 calculates a predicted position E of the target S at the next generation timing Gs of the linked echo data EdC based on the latest detected position P of the target S and the latest velocity vector V1. Then, the display processing unit 12 determines a rectangular selection range Ar centered on the calculated predicted position E. Note that the shape of the selection range Ar is not limited to a rectangle, and may be a polygon other than a rectangle, a circle, an ellipse, or a sector.

[0052] When new linked echo data EdC is stored in the storage unit 13 by the acquisition unit 11, the display processing unit 12 detects the target S in the selection range Ar based on the linked echo data EdC, and identifies coordinates indicating the detection position P of the detected target S. Then, the display processing unit 12 generates an echo image including the detection position P of the target S and the velocity vector V1 of the target S, and updates the echo image displayed on the display device 111 to the generated echo image. Note that the display processing unit 12 may generate an echo image including a predicted position E instead of or in addition to the detection position P.

[0053] Fig. 3 is a diagram showing the trail of a target object to be tracked by the radar device according to the embodiment of the invention and the trail of a clutter generation point. Fig. 3 shows the coordinates Cs of the target object S and the coordinates Cc of the clutter generation point C, which are specified by the display processing unit 12 based on five pieces of time-series linked echo data EdC. For example, the clutter is sea clutter, and the clutter generation point C is the sea surface.

[0054] 3, the fluctuation of the clutter generation point C is larger than the fluctuation of the target S. This is because clutter occurs randomly at any position on the sea surface. In a conventional radar device, there is a case where the clutter generation point C is preferentially tracked instead of the target S to be tracked. Therefore, the target tracking unit 101 according to the embodiment of the present invention has the following configuration to suppress erroneous tracking of the target S in the detection target area Ta where clutter occurs.

[0055] (Calculation of index value IN) The display processing unit 12 extracts a reflector R whose echo level is equal to or greater than a predetermined value based on the time-series echo data Ed acquired at a predetermined cycle, and calculates an index value IN indicating the wobble of the reflector R based on the extraction result obtained at that timing. For example, when the display processing unit 12 detects an unknown reflector R based on the linked echo data EdC stored in the storage unit 13 by the acquisition unit 11, it calculates an index value IN indicating the wobble of the detected reflector R. For example, the index value IN is a statistical value calculated based on the amount of change in the velocity vector V1 of the reflector R.

[0056] Fig. 4 and Fig. 5 are diagrams showing an example of a method for calculating an index value by a display processing unit in a radar device according to an embodiment of the present invention. In Fig. 4 and Fig. 5, the horizontal axis indicates the speed in the X direction, and the vertical axis indicates the speed in the Y direction. The X direction is, for example, the east-west direction. The Y direction is, for example, the north-south direction. Fig. 4 shows an absolute value Va which is an index value IN calculated based on the trail of the target S shown in Fig. 3. Fig. 5 shows an absolute value Va which is an index value IN calculated based on the trail of the clutter generation point C shown in Fig. 3.

[0057] 4 and 5, the display processing unit 12 calculates absolute values ​​VaX, VaY indicating the amount of wobble of the reflector R based on the amount of change in the velocity vector V1 of the reflector R. More specifically, when the display processing unit 12 detects the reflector R, it calculates the velocity vector V1 of the reflector R based on the coordinates of the detected reflector R, the coordinates of the reflector R in the past sweep period T, and the scan period Cp, and stores the calculated velocity vector V1 in the storage unit 13. The display processing unit 12 acquires from the storage unit 13 the four velocity vectors V1 of the reflector R calculated based on the five linked echo data EdC in time series.

[0058] Then, the display processing unit 12 calculates an absolute value Va of the difference between the maximum value of the calculated four velocity vectors V1 and the minimum value of the four velocity vectors V1 as the index value IN of the reflector R. More specifically, the display processing unit 12 calculates an absolute value VaX which is the absolute value Va of the difference between the maximum value and the minimum value of the four velocity vectors V1 in the X direction, and an absolute value VaY which is the absolute value Va of the difference between the maximum value and the minimum value of the four velocity vectors V1 in the Y direction, as the index value IN of the reflector R.

[0059] In addition, the display processing unit 12 may be configured to calculate two, three, five or more velocity vectors V1 using three, four, six or more connected echo data EdC, and calculate the absolute values ​​VaX, VaY based on the calculated velocity vectors V1.

[0060] (Determination of threshold value TH) The display processing unit 12 determines the threshold value TH based on the size of the reflector R. For example, when the display processing unit 12 detects an unknown reflector R based on the linked echo data EdC stored in the storage unit 13 by the acquisition unit 11, the display processing unit 12 determines the threshold value TH based on the size of the detected reflector R.

[0061] FIG. 6 is a diagram showing an example of a method for determining a threshold value by the display processing unit in the radar device according to the embodiment of the present invention.

[0062] With reference to FIG. 6, when the display processing unit 12 detects a reflector R, it approximates the reflector R with a polygonal reference area Ra. For example, the reference area Ra is a Baumkuchen-shaped area. More specifically, the reference area Ra is an area surrounded by two straight lines extending in the distance direction from the antenna 21 and two arcs ar1 and ar2 extending in the azimuth direction with the antenna 21 as the center. That is, the reference area Ra is an area surrounded by the arcs ar1 and ar2 of two circles centered on the antenna 21 and two line segments connecting the two ends of the arc ar1 and the two ends of the arc ar2, respectively. The display processing unit 12 approximates an area of ​​the reflector R having an echo level equal to or higher than a predetermined value with a reference area Ra in which the area of ​​the reflector R is inscribed. The reference area Ra may be, for example, a sector-shaped area.

[0063] When the display processing unit 12 approximates the reflector R with the reference area Ra, it calculates the depth length L of the reference area Ra based on the antenna 21. The display processing unit 12 also calculates the distance D between the antenna 21 and the reflector R. The display processing unit 12 also calculates the width W of the reference area Ra in the azimuth direction with the antenna 21 as the center. More specifically, the display processing unit 12 calculates the forefront width Wf, which is the width W equivalent to the length of the arc ar1, and the center width Wc, which is the width W passing through the midpoint of the reference area Ra in the depth direction.

[0064] The display processing unit 12 determines the threshold value TH based on the size of the reference region Ra. More specifically, the display processing unit 12 calculates the threshold value TH according to the following formula (1).

number

[0065] Here, α is a fixed value that is set in advance according to the expected speed, acceleration, etc. of the target S.

[0066] For example, the display processing unit 12 calculates the size of the reflector R based on the distance D between the antenna 21 and the reflector R. More specifically, regardless of the actual size of the reflector R, the smaller the distance D, the larger the size of the area of ​​the reflector R calculated by the display processing unit 12. Therefore, the display processing unit 12 corrects the length L, the front width Wf, and the center width Wc using a coefficient Cf according to the distance D, and calculates the threshold value TH using the corrected length L, the front width Wf, and the center width Wc.

[0067] (Decision making process) The display processing unit 12 performs a determination process to determine whether the index value IN is equal to or greater than the threshold value TH. More specifically, when the display processing unit 12 calculates the absolute values ​​VaX, VaY, which are the index value IN of the reflector R, and the threshold value TH, it compares the calculated absolute values ​​VaX, VaY with the calculated threshold value TH.

[0068] For example, when both absolute values ​​VaX, VaY of a reflector R are less than a threshold value TH, the display processing unit 12 tracks the reflector R as a target S. That is, the display processing unit 12 judges that the reflector R is a target S to be tracked, and determines to include the reflector R in the tracking target. Then, the display processing unit 12 starts tracking the reflector R.

[0069] On the other hand, when at least one of the absolute values ​​VaX, VaY of the reflector R is equal to or greater than the threshold value TH, the display processing unit 12 does not track the reflector R. In other words, the display processing unit 12 determines that the reflector R is not a target S to be tracked, and determines to exclude the reflector R from the tracking target in the tracking process.

[0070] For example, when at least one of the absolute values ​​VaX, VaY of the reflector R detected based on the linked echo data EdC is equal to or greater than the threshold value TH, the display processing unit 12 excludes the reflector R from the tracking target in the tracking process based on the linked echo data EdC and other linked echo data EdC generated after the linked echo data EdC. More specifically, when at least one of the absolute values ​​VaX, VaY of the reflector R is equal to or greater than the threshold value TH in the linked echo data EdC generated first after the target tracking unit 101 is activated, the display processing unit 12 maintains the state in which the reflector R is excluded from the tracking target even if the absolute values ​​VaX, VaY of the reflector R transition to less than the threshold value TH in the other linked echo data EdC generated after the linked echo data EdC.

[0071] Fig. 7 is a diagram showing an example of an echo image generated by a display processing unit in a radar device according to an embodiment of the present invention. Triangles in Fig. 7 indicate detection positions Pt1, Pt2, and Pt3, which are detection positions P of a reflector R at times t1, t2, and t3, respectively. Circles in Fig. 7 indicate predicted positions Et1, Et2, and Et3, which are predicted positions E of the reflector R at times t1, t2, and t3, respectively. Times t1, t2, and t3 are generation timings Gs of three pieces of time-series linked echo data EdC. For the sake of explanation, Fig. 7 shows a predicted position Et that is not included in the echo image in addition to a detection position Pt that is included in the echo image.

[0072] 7, when the absolute values ​​VaX, VaY of the reflector R detected based on the connected echo data EdC generated at times t1, t2 are less than a threshold value TH, the display processing unit 12 tracks the reflector R as a target S. Then, the display processing unit 12 generates an echo image including triangular icons indicating the detection positions Pt1, Pt2 of the reflector R at times t1, t2.

[0073] Thereafter, when at least one of the absolute values ​​VaX, VaY of the reflector R detected based on the connected echo data EdC generated at time t3 is equal to or greater than the threshold value TH, the display processing unit 12 determines that the reflector R is not a target S to be tracked, and determines to exclude the reflector R from the tracking target in the tracking process after time t3. Then, the display processing unit 12 does not generate an echo image showing the detection position Pt3 of the reflector R after time t3.

[0074] 8 is a diagram showing an example of an echo image generated by the display processing unit in the radar device according to the embodiment of the present invention. As described above, the display processing unit 12 may generate an echo image including a predicted position E instead of or in addition to the detected position P. In this case, the display processing unit 12 generates the echo image shown in FIG.

[0075] For example, the display processing unit 12 further performs background tracking processing to track a reflector R that has been excluded from the tracking target in the tracking processing. While the display processing unit 12 performs processing to display the tracking result of the target S as described above, it does not perform processing to display the tracking result of the reflector R tracked in the background tracking processing. That is, the display processing unit 12 generates an echo image that indicates the position, etc. of the target S and does not include information such as the position, etc. of the reflector R, and performs processing to display the generated echo image on the display device 111.

[0076] The display processing unit 12 may be configured to perform a process of displaying the tracking result of the reflector R tracked in the background tracking process in addition to the tracking result of the target S. In this case, for example, the display processing unit 12 performs a process of displaying the tracking result of the target S tracked in the tracking process and the tracking result of the reflector R tracked in the background tracking process in different modes. Specifically, the display processing unit 12 performs a process of displaying an icon indicating the target S and an icon indicating the reflector R in different colors or shapes.

[0077] FIG. 9 is a diagram showing another example of an echo image generated by a display processing unit in a radar device according to an embodiment of the present invention. The solid triangles in FIG. 9 indicate detection positions Pt1, Pt2, and Pt5, which are detection positions P of reflectors R detected at times t1, t2, and t5, respectively. The dashed triangles in FIG. 9 indicate detection positions Pt3 and Pt4, which are detection positions P of reflectors R at times t3 and t4, respectively. The circles in FIG. 9 indicate predicted positions Et1, Et2, Et3, Et4, and Et5, which are predicted positions E of the reflectors R at times t1, t2, t3, t4, and t5, respectively. The times t1, t2, t3, t4, and t5 are the generation timings Gs of five connected echo data EdC in a time series. For the sake of explanation, FIG. 9 shows a predicted position Et that is not included in the echo image in addition to the detection position Pt included in the echo image.

[0078] 9, when at least one of the absolute values ​​VaX, VaY of the reflector R detected based on the linked echo data EdC generated at time t3 is equal to or greater than the threshold value TH, and at least one of the absolute values ​​VaX, VaY of the reflector R detected based on the linked echo data EdC generated at time t4 is equal to or greater than the threshold value TH, the display processing unit 12 determines that the reflector R is not a target S to be tracked, and performs background tracking processing at times t3 and t4. Then, the display processing unit 12 generates an echo image including a dashed triangular icon indicating the detection positions Pt3, Pt4 of the reflector R at times t3, t4.

[0079] Thereafter, when the absolute values ​​VaX, VaY of the reflector R detected based on the connected echo data EdC generated at time t5 are less than the threshold value TH, the display processing unit 12 ends the background tracking process and resumes the tracking process for tracking the reflector R as the target S. Then, the display processing unit 12 generates an echo image including a solid-line triangular icon indicating the detection position Pt5 of the reflector R at time t5.

[0080] FIG. 10 is a diagram showing another example of an echo image generated by the display processing unit in the radar device according to the embodiment of the present invention. As described above, the display processing unit 12 may generate an echo image including a predicted position E instead of or in addition to the detected position P. In this case, the display processing unit 12 generates an echo image shown in FIG. 10. That is, when performing background tracking processing at times t3 and t4, the display processing unit 12 generates an echo image including a square icon indicating the predicted positions Et3 and Et4 of the reflector R at times t3 and t4. Thereafter, when ending the background tracking processing at time t5, the display processing unit 12 generates an echo image including, for example, a solid-line circle icon indicating the predicted position Et5 of the reflector R at time t5.

[0081] Fig. 11 is a diagram showing another example of an echo image generated by a display processor in a radar device according to an embodiment of the present invention. Solid triangles in Fig. 11 indicate detection positions Pt1, Pt2, Pt3, Pt4, and Pt5, respectively. Circles in Fig. 11 indicate predicted positions Et1, Et2, and Et5, respectively. Squares in Fig. 11 indicate predicted positions Et3 and Et4, respectively.

[0082] 11, when at least one of the absolute values ​​VaX, VaY of the reflector R detected based on the linked echo data EdC generated at time t3 is equal to or greater than the threshold value TH, and at least one of the absolute values ​​VaX, VaY of the reflector R detected based on the linked echo data EdC generated at time t4 is equal to or greater than the threshold value TH, the display processing unit 12 determines that the reflector R is not a target S to be tracked, and excludes the reflector R detected based on the linked echo data EdC from the tracking target in the tracking process. Then, the display processing unit 12 performs an interpolation process to interpolate the position of the target S at times t3 and t4 with the predicted positions Et3 and Et4. Then, the display processing unit 12 generates an echo image including a square icon indicating the position of the target S interpolated in the interpolation process.

[0083] Thereafter, when the absolute values ​​VaX, VaY of the reflector R detected based on the connected echo data EdC generated at time t5 are less than the threshold value TH, the display processing unit 12 ends the interpolation process and resumes the tracking process for tracking the reflector R as the target S. Then, the display processing unit 12 generates an echo image including a solid-line triangular icon indicating the detection position Pt5 of the reflector R at time t5.

[0084] As described above, the display processing unit 12 may generate an echo image including the predicted position E instead of or in addition to the detected position P. In this case, the display processing unit 12 generates an echo image shown in FIG. 10. That is, when the display processing unit 12 performs the interpolation process at times t3 and t4, the display processing unit 12 generates an echo image including a square icon indicating the predicted positions Et3 and Et4 of the reflector R at times t3 and t4. Thereafter, when the display processing unit 12 ends the interpolation process at time t5, the display processing unit 12 generates an echo image including, for example, a solid-line circle icon indicating the predicted position Et5 of the reflector R at time t5.

[0085] Fig. 12 is a diagram showing the configuration of a radar device according to a modified example of the embodiment of the present invention. With reference to Fig. 12, compared to the radar device 201, the radar device 202 includes a target tracking unit 102 instead of the target tracking unit 101. Compared to the target tracking unit 101, the target tracking unit 102 includes a display processing unit 15 instead of the display processing unit 12, and further includes a sway value calculation unit 14.

[0086] The fluctuation value calculation unit 14 calculates the index value IN. More specifically, the fluctuation value calculation unit 14 calculates absolute values ​​VaX, VaY as the index value IN in the same manner as the display processing unit 12. The fluctuation value calculation unit 14 outputs the calculated absolute values ​​VaX, VaY to the display processing unit 15.

[0087] The display processing unit 15 does not calculate the index value IN, as compared with the display processing unit 12. The display processing unit 15 receives the absolute values ​​VaX, VaY from the fluctuation value calculation unit 12 and performs a determination process to determine whether the received absolute values ​​VaX, VaY are equal to or greater than the threshold value TH. The display processing unit 15 may perform the above-mentioned interpolation process or the above-mentioned background tracking process according to the determination result in the determination process.

[0088] [Operation flow] The radar device according to the embodiment of the present invention includes a computer including a memory, and a processor such as a CPU in the computer reads out from the memory a program including some or all of the steps of the following flowcharts and executes it. The program of this device can be installed from the outside. The program of this device is distributed in a state stored on a recording medium or via a communication line.

[0089] FIG. 13 is a flowchart showing an example of an operation performed by the target tracking unit in the radar device according to the embodiment of the present invention when performing tracking processing.

[0090] 13, first, the target tracking unit 101 generates concatenated echo data EdC by concatenating N pieces of divided echo data EdD received from the radar unit 20 (step S11).

[0091] Next, the target tracking unit 101 performs a process of tracking the target S based on the generated linked echo data EdC, and displaying the tracking result of the target S. More specifically, the target tracking unit 101 performs a process of generating an echo image indicating the coordinates of the target S and the velocity vector V1 of the target S, and displaying the generated echo image on the display device 111 (step S12).

[0092] Next, the target tracking unit 101 repeats the processes of steps S11 and S12 based on the generated linked echo data EdC until an unknown reflector R is detected (NO in step S13).

[0093] Next, when the target tracking unit 101 detects an unknown reflector R based on the generated linked echo data EdC (YES in step S13), the target tracking unit 101 calculates an index value IN of the reflector R using the five time-series linked echo data EdC. More specifically, the target tracking unit 101 calculates absolute values ​​VaX, VaY of the reflector R as the index value IN of the reflector R (step S14).

[0094] Next, the target tracking unit 101 determines the threshold value TH based on the size of the reflector R. More specifically, the target tracking unit 101 approximates the reflector R with a polygonal reference area Ra, and calculates the threshold value TH according to the above-mentioned formula (1) based on the size of the reference area Ra (step S15).

[0095] Next, the target tracking unit 101 performs a determination process to determine whether or not the index value IN of the reflector R is equal to or greater than a threshold value TH (step S16).

[0096] Next, if at least one of the absolute values ​​VaX, VaY, which are the index values ​​IN of the reflector R, is equal to or greater than the threshold value TH (NO in step S17), the target tracking unit 101 determines to exclude the reflector R from the tracking target (step S18).

[0097] Next, the target tracking unit 101 repeats the processes of steps S11 and S12 until a new unknown reflector R is detected (NO in step S13).

[0098] On the other hand, if both of the absolute values ​​VaX, VaY of the reflector R are less than the threshold value TH (YES in step S17), the target tracking unit 101 determines that the reflector R is a target S to be tracked, and decides to include the reflector R in the tracking target (step S19).

[0099] Next, the target tracking unit 101 repeats the processes of steps S11 and S12 until a new unknown reflector R is detected (NO in step S13).

[0100] When it is determined in step S18 that the reflector R is to be removed from the tracking target, the target tracking unit 101 may start a background tracking process for tracking the reflector R. In this case, for example, the target tracking unit 101 performs a process of displaying the tracking result of the target S in the process of step S12, but does not perform a process of displaying the tracking result of the reflector R tracked in the background tracking process. That is, the target tracking unit 101 tracks the reflector R in the background tracking process, but generates an echo image that does not include information such as the position of the reflector R, and performs a process of displaying the generated echo image on the display device 111.

[0101] In addition, in the target tracking unit 101 according to the embodiment of the present invention, the display processing unit 12 is configured to calculate the threshold value TH according to the above-mentioned formula (1), but this is not limited to this. The display processing unit 12 may be configured to determine the threshold value TH based on AIS information received from other ships in addition to the size of the reflector R. In this case, the display processing unit 12 determines the threshold value TH based on the size of other ships around the ship 1, which is indicated by the AIS information.

[0102] Furthermore, the display processing unit 12 may be configured to calculate the threshold value TH according to another formula instead of the above-mentioned formula (1). For example, in the tracking process, when tracking a point on the target S that is closest to the antenna 21, the fluctuation in the azimuth direction of the target S becomes dominant and the fluctuation component in the distance direction can be ignored, so the display processing unit 12 may calculate the threshold value TH according to the following formula (2).

number

[0103] Here, k is a constant, for example, k is greater than zero and less than or equal to 1.

[0104] On the other hand, when tracking the center point of the target S in the tracking process, the display processing unit 12 calculates the threshold value TH according to the above-mentioned formula (1) since the component of fluctuation in the distance direction cannot be ignored.

[0105] (Another example of the index value IN) Although the display processing unit 12 is configured to calculate absolute values ​​VaX and VaY as index values ​​IN indicating the wobble of the reflector R, the present invention is not limited to this. The display processing unit 12 may be configured to calculate other statistical values ​​based on the amount of change in a plurality of velocity vectors V1 as the index value IN. The statistical value may be an average value, a median value, or a standard deviation.

[0106] For example, the display processing unit 12 extracts a plurality of X-direction components Ix and a plurality of Y-direction components Iy from each of the plurality of velocity vectors V1.

[0107] Then, instead of the absolute value VaX, the display processing unit 12 may calculate, as the index value IN, the variance of the multiple X-direction components Ix, the standard deviation of the multiple X-direction components Ix, the average deviation of the multiple X-direction components Ix, the interquartile range of the multiple X-direction components Ix, or the interquartile deviation of the multiple X-direction components Ix.

[0108] In addition, instead of the absolute value VaY, the display processing unit 12 may calculate the variance of the multiple Y-direction components Iy, may calculate the standard deviation of the multiple Y-direction components Iy, may calculate the average deviation of the multiple Y-direction components Iy, may calculate the interquartile range of the multiple Y-direction components Iy, or may calculate the interquartile deviation of the multiple Y-direction components Iy as the index value IN.

[0109] In addition, the display processing unit 12 may calculate, as the index value IN, a statistical value of the angle formed by multiple velocity vectors V1, instead of the absolute values ​​VaX, VaY, or may calculate a statistical value of the cosine distance of multiple velocity vectors V1.

[0110] Furthermore, the display processing unit 12 may calculate, as the index value IN, a value that is a combination of the above-mentioned multiple statistical values.

[0111] In addition, the index value IN is a statistical value calculated based on the amount of change in the velocity vector V1 of the reflector R, but is not limited thereto. The index value IN may be a statistical value calculated based on the amount of change in the velocity of the reflector R. More specifically, the display processing unit 12 calculates a plurality of scalar velocities Sv corresponding to the plurality of velocity vectors V1, respectively. The scalar velocity Sv is a scalar amount of the velocity of the reflector R. The display processing unit 12 may calculate, as the index value IN, an absolute value of a difference between a maximum value and a minimum value of the calculated plurality of scalar velocities Sv, may calculate a variance of the plurality of scalar velocities Sv, may calculate a standard deviation of the plurality of scalar velocities Sv, may calculate an average deviation of the plurality of scalar velocities Sv, may calculate an interquartile range of the plurality of scalar velocities Sv, or may calculate an interquartile deviation of the plurality of scalar velocities Sv.

[0112] The index value IN may be a statistical value calculated based on the amount of change in the position of the reflector R. More specifically, the display processing unit 12 calculates the amount of change Vp in the position of the reflector R for each scan period Cp using a plurality of detection positions P immediately adjacent to the reflector R. The amount of change Vp in the position is a scalar amount of the moving distance of the reflector R. The display processing unit 12 may calculate, as the index value IN, the absolute value of the difference between the maximum value and the minimum value of the calculated amount of change Vp in the plurality of position changes, may calculate the variance of the plurality of amount of change Vp in the plurality of position changes, may calculate the standard deviation of the plurality of amount of change Vp in the plurality of position changes, may calculate the average deviation of the plurality of amount of change Vp in the plurality of position changes, may calculate the interquartile range of the plurality of amount of change Vp, or may calculate the interquartile deviation of the plurality of amount of change Vp in the plurality of position changes.

[0113] The above-described embodiments should be considered as illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0114] 1 ship 11 Acquisition Department 12,15 Display processing unit 13 Storage section 14 Fluctuation value calculation section 20 Radar Section 21 Antenna 22 Transmitter / receiver 23 Signal Processing Section 101,102 Target tracking unit 111 Display device 201,202 Radar equipment Ta Detection area S target Cs,Cc coordinates V1 Velocity Vector VaX, VaY absolute value R reflector Ra reference area Wf Front width Wc center width L Length D Distance ar1,ar2 Circular arcs

Claims

1. A target tracking device that detects and tracks a target in a detection target area at a predetermined cycle, an acquisition unit that acquires echo data indicating a correspondence relationship between a position in the detection target area and a level of a reflected wave of an electromagnetic wave transmitted via an antenna and reflected at the position; a tracking unit that performs a tracking process to track the target based on the echo data; a calculation unit that extracts a reflector having a reflected wave level equal to or higher than a predetermined value based on the time-series echo data acquired at the timing, and calculates an index value indicating a fluctuation of the reflector based on the extraction result obtained at the timing; A determination unit that determines whether the index value is equal to or greater than a threshold value.

2. 2. The target tracking device according to claim 1, wherein the tracking unit tracks the reflector as the target when the index value is less than the threshold value, and excludes the reflector from being tracked in the tracking process when the index value is equal to or greater than the threshold value.

3. The tracking unit further performs a background tracking process to track the reflector that is excluded from the tracking target in the tracking process, 3. The target tracking device according to claim 2, wherein the tracking unit performs a process of displaying a tracking result of the target tracked in the tracking process, but does not perform a process of displaying a tracking result of the reflector tracked in the background tracking process.

4. The tracking unit further performs a background tracking process to track the reflector that is excluded from the tracking target in the tracking process, 3. The target tracking device according to claim 2, wherein the tracking unit performs processing to display a tracking result of the target tracked in the tracking processing and a tracking result of the reflector tracked in the background tracking processing in different formats.

5. The acquisition unit repeatedly acquires the echo data, 3. The target tracking device according to claim 2, wherein, when the index value indicating the wobble of the reflector detected based on the first echo data is equal to or greater than the threshold value, the tracking unit excludes the reflector from a tracking target in the tracking process based on the first echo data and the echo data acquired after the first echo data.

6. The target tracking device according to claim 2 , wherein the tracking unit performs an interpolation process for interpolating the position of the target with a predicted position of the target when the reflector is excluded from the tracking target in the tracking process.

7. The target tracking device further comprises: The target tracking device according to claim 1 , further comprising a determination unit that determines the threshold value based on a size of the reflector.

8. The target tracking device according to claim 7 , wherein the determination unit approximates the reflector with a polygonal reference area and determines the threshold value based on a size of the reference area.

9. 8. The target tracking device according to claim 7, wherein the determination unit approximates the reflector with a reference area surrounded by two straight lines extending in a distance direction from the antenna and two arcs extending in an azimuth direction with the antenna as a center, and determines the threshold value based on a size of the reference area.

10. The target tracking device according to claim 7 , wherein the determination unit calculates a size of the reflector based on a distance between the antenna and the reflector.

11. The target tracking device according to claim 7 , wherein the determination unit determines the threshold value further based on AIS (Automatic Identification System) information.

12. The target tracking device according to claim 1 , wherein the calculation unit calculates the index value based on an amount of change in a velocity vector of the reflector.

13. The target tracking device according to claim 1 , wherein the calculation unit calculates the index value based on an amount of change in speed of the reflector.

14. The target tracking device according to claim 1 , wherein the calculation unit calculates the index value based on an amount of change in a position of the reflector.

15. A target tracking method for a target tracking device that detects and tracks a target in a detection target area at a predetermined cycle, comprising: acquiring echo data indicating a correspondence relationship between a position in the detection target area and a level of a reflected wave of an electromagnetic wave transmitted via an antenna and reflected at the position; performing a tracking process for tracking the target based on the echo data; extracting a reflector having a reflected wave level equal to or higher than a predetermined value based on the time-series echo data acquired at the timing, and calculating an index value indicating a fluctuation of the reflector based on the extraction result obtained at the timing; determining whether the index value is equal to or greater than a threshold value.

16. A target tracking program used in a target tracking device that detects and tracks a target in a detection target area at a predetermined cycle, A process of acquiring echo data indicating a correspondence relationship between a position in the detection target area and a level of a reflected wave of an electromagnetic wave transmitted via an antenna and reflected at the position; a tracking process for tracking the target based on the time-series echo data acquired at the timing; A process of extracting a reflector having a reflected wave level equal to or higher than a predetermined value based on the time-series echo data acquired at the timing, and calculating an index value indicating a fluctuation of the reflector based on the extraction result obtained at the timing; A target tracking program for causing a computer to execute a process of determining whether the index value is equal to or greater than a threshold value.

Images