Radar signal processing device and radar signal processing program

Abstract

To provide a technique for avoiding excessive division of a target by micro-Doppler.SOLUTION: A radar signal processing device (5) comprises a ranging point information acquisition section (53), a pre-segment generation section (541), and a segment generation section (542). The ranging point information acquisition section acquires ranging point information including position information and speed information at each of a plurality of ranging points acquired by irradiating radar waves. The pre-segment generation section generates a pre-segment (PS) as a set of the ranging points by grouping the plurality of ranging points on the basis of the ranging point information. The segment generation section generates a composite segment as a set of the ranging points included in a first pre-segment and a second pre-segment on the basis of a positional relation between the first pre-segment which is one of a plurality of pre-segments, and the second pre-segment which is another one of the pre-segments.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a radar signal processing device Place and a radar signal processing program.

Background Art

[0002] The radar signal processing device described in Patent Document 1 includes a velocity vector calculation unit, a grouping processing unit, an average relative velocity vector calculation unit, and a distance correction unit. The velocity vector calculation unit calculates a composite relative velocity vector of a virtual object including each measurement point based on the relative velocity vectors of a plurality of measurement points detected by a single or a plurality of radars. The grouping processing unit groups virtual objects having equal composite relative velocity vectors of the calculated plurality of virtual objects as real objects. The average relative velocity vector calculation unit calculates an average relative velocity vector obtained by averaging the composite relative velocity vectors of the grouped real objects. The distance correction unit corrects the distance of each measurement point based on the calculated average relative velocity vector. Note that the measurement point may also be referred to as a measurement point or a ranging point.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When using radar to detect a moving vehicle, many measurement points are detected from the entire vehicle. In particular, measurement points on parts that move differently from the vehicle body (e.g., wheels) will detect different velocities than those of the vehicle body. Measurement points that have a velocity component that differs from the surroundings in this way are called micro-Doppler points. Because micro-Doppler points have velocities that are far removed from the overall average velocity, they may be mistakenly treated as independent targets. Specifically, for example, according to the radar signal processing device described in Patent Document 1, the vehicle body and wheels may be judged as separate targets.

[0005] This invention has been made in view of the circumstances illustrated above. Specifically, this invention provides, for example, a technique to avoid over-segmentation of an object by micro-Doppler. [Means for solving the problem]

[0006] The radar signal processing device (5) described in claim 1 is A distance measurement point information acquisition unit (53) acquires distance measurement point information, including position information and velocity information at each of the multiple distance measurement points acquired by radar wave irradiation, A pre-segment generation unit (541) generates a pre-segment (PS) as a set of distance points by grouping a plurality of distance points based on the distance point information acquired by the distance point information acquisition unit, A segment generation unit (542) generates a composite segment as a set of distance measurement points included in the first presegment and the second presegment, based on the positional relationship between a first presegment, which is one of the multiple presegments generated by the presegment generation unit, and a second presegment, which is another of the multiple presegments. Equipped with picture, The segment generation unit generates the composite segment on the condition that the distance between the first pre-segment and the second pre-segment is within a threshold and that one of the distance measurement points included in the first pre-segment and the distance measurement point included in the second pre-segment is located above the other. Claim 4 The radar signal processing program described is a computer program executed by the radar signal processing device (5), A process for acquiring distance measurement point information, including position information and velocity information, for each of the multiple distance measurement points acquired by radar wave irradiation, A process to generate a presegment (PS) as a set of distance points by grouping multiple distance points based on the acquired distance point information, A process to generate a composite segment as a set of distance measurement points included in the first presegment and the second presegment, based on the positional relationship between a first presegment, which is one of the multiple presegments generated by the presegment generation unit, and a second presegment, which is another of the multiple presegments, of Including, The composite segment is generated on the condition that the distance between the first pre-segment and the second pre-segment is within a threshold and that one of the distance measurement points included in the first pre-segment and the distance measurement point included in the second pre-segment is located above the other.

[0007] In addition, each element in the application documents may be given a reference numeral in parentheses. However, such reference numerals merely indicate one example of the correspondence between the element and the specific means described in the embodiments described later. Therefore, the present invention is not limited in any way by the notation of the above reference numerals. [Brief explanation of the drawing]

[0008] [Figure 1] This is a block diagram showing a schematic configuration of a radar system equipped with a target recognition device as a radar signal processing device according to one embodiment of the present invention. [Figure 2] This block diagram shows an example of the functional configuration of the target recognition device shown in Figure 1. [Figure 3] Figure 1 is a schematic diagram illustrating the operation of the target recognition device, along with an example of an object to be recognized by the device. [Figure 4] Figure 1 is a schematic diagram illustrating the operation of the target recognition device, along with another example of an object to be recognized by the device. [Figure 5] Figure 4 is a schematic diagram showing how a composite segment is generated from multiple pre-segments. [Figure 6]Figure 1 is a flowchart illustrating the overview of the operation of the target recognition device. [Figure 7] Figure 1 is a flowchart illustrating the overview of the operation of the target recognition device. [Figure 8] This is a perspective view showing yet another example of an object to be recognized by the target recognition device shown in Figure 1. [Figure 9] Figure 1 is a schematic diagram illustrating the general operation of the target recognition device. [Modes for carrying out the invention]

[0009] (Embodiment) The embodiments of the present invention will be described below with reference to the drawings. Note that various modifications applicable to a single embodiment may hinder understanding of that embodiment if they are inserted in the middle of the series of descriptions of that embodiment. Therefore, modifications will be described collectively after the series of descriptions of a single embodiment.

[0010] (Overall system configuration) Referring to Figure 1, the in-vehicle system 1 is configured to be installed in a vehicle such as an automobile traveling on a road, and to control the operation of the vehicle. Hereinafter, the vehicle equipped with the in-vehicle system 1 will be referred to as "the vehicle." "Vehicle operation" here refers to, for example, driving control operations, information presentation operations or warning operations to the occupants, etc. Specifically, the in-vehicle system 1 is configured to detect various targets, including at least other vehicles, within a detection area that is at least a portion of the area surrounding the vehicle, and to use the detection results for vehicle control such as warnings to the occupants of the vehicle or driving assistance.

[0011] Specifically, in this embodiment, the in-vehicle system 1 includes a radar sensor 2, a vehicle speed sensor 3, a yaw rate sensor 4, an object recognition device 5, and a driving assistance device 6. That is, the in-vehicle system 1 has a configuration as a so-called driving automation system. The "driving automation system" is a higher-level concept that includes an automatic driving system and a driving assistance system. "Automatic driving" refers to the driving automation level in which the driving automation system corresponding to levels 3 to 5 in the standard "SAE J3016" published by SAE International is responsible for and executes all dynamic driving tasks. The "dynamic driving task" is all operational and tactical functions that need to be performed in real time when operating a vehicle on road traffic, excluding strategic functions. "Strategic functions" include route planning, destination selection, etc., and specifically include determining or selecting "whether to go or not, when, where, and how to go". "Driving assistance" refers to the driving automation level corresponding to levels 1 to 2 in "SAE J3016", in which the driving automation system continuously executes the longitudinal vehicle motion control subtask and / or the lateral vehicle motion control subtask of the dynamic driving tasks in a specific limited area. Such vehicle motion control subtasks include, for example, starting, accelerating, decelerating, braking, stopping, steering, changing the shift range, etc. That is, "driving assistance" includes at least one of, for example, a lane keeping function, a lane change assistance function, an automatic lane change function, a following function for the preceding vehicle, a collision avoidance function, etc.

[0012] The radar sensor 2 has a configuration as a so-called Doppler radar that can obtain the relative moving speed and displacement of the observation target by observing the frequency shift due to the Doppler effect. In addition, the radar sensor 2 is configured to be able to detect the arrival direction of the reflected wave. Specifically, in this embodiment, the radar sensor 2 has a configuration as a laser radar sensor (that is, a LiDAR sensor) capable of acquiring the Doppler speed. LiDAR is an abbreviation for Light Detection and Ranging or Laser Imaging Detection and Ranging.

[0013] The vehicle speed sensor 3 is provided to detect the vehicle speed of the host vehicle. The yaw rate sensor 4 is provided to detect the yaw rate acting on the host vehicle. In addition, the in-vehicle system 1 is equipped with various sensors (not shown), such as a camera, an accelerator position sensor, an acceleration sensor, etc., for detecting information and physical quantities related to the driving operation state and driving behavior of the host vehicle.

[0014] The target recognition device 5 is connected via an in-vehicle communication line to various sensors provided in the in-vehicle system 1, including the radar sensor 2, the vehicle speed sensor 3, and the yaw rate sensor 4. The target recognition device 5 is configured to recognize targets around the host vehicle based on the information or signals acquired by these sensors. That is, the target recognition device 5 as the radar signal processing device in the present invention executes a target recognition operation by processing the radar signal, which is the measurement information output from the radar sensor 2. And the target recognition device 5 is connected to the driving support device 6 via an in-vehicle communication line so as to output the target recognition result to the driving support device 6. The driving support device 6 is configured to execute vehicle control operations, such as a warning operation and a collision avoidance operation, based on the target recognition result received from the target recognition device 5.

[0015] The target recognition device 5 comprises a processor 51 and a memory 52. ​​The processor 51 has a configuration as either a CPU or an MPU. CPU stands for Central Processing Unit. MPU stands for Micro Processing Unit. The memory 52 has a configuration as a non-volatile, non-transitional, tangible storage medium that holds programs executed by the processor 51 and various data such as lookup tables required when executing such programs. Specifically, the memory 52 comprises at least one of the following: ROM, flash memory, magnetic disk, etc. ROM stands for Read Only Memory. The target recognition device 5 is configured such that the processor 51 reads a program from the memory 52 and executes it, thereby performing at least target detection processing.

[0016] Figure 2 shows the functional configuration realized by the target recognition device 5 when the processor 51 reads and executes the target recognition program from the memory 52. ​​Figure 3 shows the detection of a distance measurement point P on a target, including another vehicle V traveling in the same direction as the vehicle while the vehicle is moving forward. Figures 4 and 5 show enlarged views of the detection of a distance measurement point P near the left front wheel of another vehicle V approaching the vehicle. A distance measurement point P is a point on the target where radar waves are presumed to have been reflected, and is also called a "measurement point" or "reflection point". As shown in Figure 2, the target recognition device 5 has a distance measurement point information acquisition unit 53, a clustering processing unit 54, a tracking processing unit 55, and a target output processing unit 56 as functional configurations realized by program execution. The details of each functional configuration in the target recognition device 5 according to this embodiment will be described below with reference to Figures 2 to 5.

[0017] The distance measurement point information acquisition unit 53 is configured to acquire distance measurement point information output from the radar sensor 2. The distance measurement point information includes position information and speed information at the distance measurement point P acquired by radar wave irradiation. The speed information is the relative speed of the distance measurement point P with respect to the vehicle itself, and is expressed as a negative value when approaching and a positive value when moving away. The position information can be expressed in polar coordinates, which specify the position by the distance and direction to the distance measurement point P with respect to the vehicle itself, or in Cartesian coordinates set with respect to the vehicle itself. Specifically, the distance measurement point information acquisition unit 53 is configured to retain the distance measurement point information over time for each measurement cycle.

[0018] The clustering processing unit 54 performs clustering on the distance measurement point information acquired by the distance measurement point information acquisition unit 53. Clustering is a process that groups (i.e., divides) the distance measurement points P detected in a given measurement cycle and defines multiple distance measurement points P belonging to the same group as being reflected by a single target. Details of the clustering process according to this embodiment will be described later. The tracking processing unit 55 performs tracking processing to track the target in a time series using known tracking processing methods such as the Kalman filter method or the α-β filtering method. The target output processing unit 56 outputs the target recognition result, including the processing result by the tracking processing unit 55, to the driver support device 6.

[0019] In this embodiment, the clustering processing unit 54 includes a pre-segment generation unit 541 and a segment generation unit 542. The pre-segment generation unit 541 generates a pre-segment PS as a linear set of distance measurement points P by grouping multiple distance measurement points P based on distance measurement point information acquired by the distance measurement point information acquisition unit 53. Specifically, the pre-segment generation unit 541 generates the pre-segment PS using the grouping conditions of proximity between distance measurement points P and small speed difference, which are conventional clustering methods. The segment generation unit 542 generates a segment SG that is the target of tracking processing by the tracking processing unit 55 based on the pre-segment PS generated by the pre-segment generation unit 541.

[0020] In this embodiment, the segment generation unit 542 generates a segment SG as a set of distance measurement points P included in a plurality of pre-segments PS when a predetermined relationship is satisfied that determines that a plurality of pre-segments PS belong to the same target. A segment SG that includes all the distance measurement points P included in a plurality of pre-segments PS that satisfy such predetermined relationship, that is, a segment SG consisting of such a plurality of pre-segments PS, will be hereinafter referred to as a "composite segment". On the other hand, if a single pre-segment PS does not satisfy the conditions for generating a composite segment with other pre-segments PS, the segment generation unit 542 will use that single pre-segment PS as the segment SG. Hereinafter, in determining whether or not to generate a composite segment, two pre-segments PS will be considered for the sake of simplicity in the explanation. One of these two pre-segments PS will be referred to as the "pre-segment of interest," and the other as the "pre-segment of reference." The "pre-segment of interest" may also be referred to as the "first pre-segment." The "pre-segment of reference" may also be referred to as the "second pre-segment."

[0021] Specifically, the “predetermined relationship” referred to here includes, for example, the positional relationship between the pre-segment of interest and the reference pre-segment. More specifically, the segment generation unit 542 generates a composite segment from the pre-segment of interest and the reference pre-segment, provided that the pre-segment of interest and the reference pre-segment satisfy all four of the following conditions. • The distance between the pre-segment of interest and the reference pre-segment must be within the threshold. The distance measurement point P included in the pre-segment of interest and the distance measurement point P included in the reference pre-segment are in a hierarchical relationship, or the pre-segment of interest surrounds the reference pre-segment. • The focus presegment consists of distance measurement points P corresponding to the moving target. • The size of the reference presegment must be within the threshold.

[0022] (Operation overview) The following describes the general operation of the target recognition device 5 according to this embodiment, as well as the general methods and programs executed by the target recognition device 5, along with the effects achieved therefrom. In the following description, the target recognition device 5 having the above configuration, and the methods (i.e., radar signal processing methods) and programs (i.e., radar signal processing programs) executed thereby, may be collectively referred to simply as "this embodiment."

[0023] As shown in Figures 3 and 4, when detecting another vehicle V in motion using radar, many distance measurement points P are detected from the entirety of the other vehicle V. Here, there are parts that move differently from the movement of the vehicle body Vb, such as the wheels Vt. At the distance measurement points P of such parts, a different velocity is detected than at the distance measurement points P of the vehicle body Vb. Distance measurement points P that have a velocity component that is partially different from the surroundings in this way are called micro-Doppler points. For more information on micro-Doppler points, please refer to Japanese Patent Publication No. 2021-124422 and Japanese Patent Publication No. 2021-188922, etc. Such micro-Doppler points have a velocity that is far removed from the overall average velocity of the other vehicle V. For this reason, according to the prior art (i.e., the radar signal processing device described in Patent Document 1), such micro-Doppler points may be mistakenly processed as independent targets. Specifically, for example, according to the prior art, the vehicle body Vb and the wheels Vt may be judged as separate targets. In this regard, even with conventional technology, it is possible to determine that the vehicle body Vb and the wheels Vt are the same target by relaxing the speed threshold in grouping. However, this can lead to problems such as the other vehicle V and the rubber pole R being mistakenly identified as the same target when another vehicle V is passing very close to a rubber pole R which is a stop target, as shown in Figure 3.

[0024] Therefore, the inventor focused on the following points. Specifically, referring to Figure 3, for example, the vehicle body Vb is usually located above the wheel Vt. For this reason, there is a high probability that a distance measuring point P or a collection of distance measuring points P corresponding to the vehicle body Vb is located above a distance measuring point P or a collection of distance measuring points P corresponding to the wheel Vt. Conversely, there should be no distance measuring point P or a collection of distance measuring points P corresponding to the rubber pole R. Also, referring to Figure 4, the side of a distance measuring point P or a collection of distance measuring points P corresponding to the wheel Vt is surrounded by a distance measuring point P or a collection of distance measuring points P corresponding to the vehicle body Vb.

[0025] Therefore, for parts such as wheels Vt that are included in another vehicle V but are detected at a different speed from the vehicle body Vb, a pre-segment PS or distance measuring point P corresponding to the vehicle body Vb exists above the pre-segment PS corresponding to that part. Alternatively, the pre-segment PS corresponding to that part is surrounded by the pre-segment PS or distance measuring point P corresponding to the vehicle body Vb. In contrast, in the case of a separate marker such as a rubber pole R that is close to another vehicle V, there is no distance measuring point P or pre-segment PS above it, and there are no distance measuring points P or pre-segment PS surrounding such a separate marker.

[0026] Therefore, in this embodiment, when multiple pre-segments PS satisfy a predetermined relationship that should be determined to belong to the same target, a segment SG is generated as a set of distance measurement points P included in them. That is, this embodiment integrates, combines, synthesizes, or merges these multiple pre-segments PS. Alternatively, this embodiment connects a pre-segment of interest to a reference pre-segment. Specifically, this embodiment generates a composite segment based on the positional relationship between multiple pre-segments PS. For example, this embodiment generates a composite segment on the condition that the distance between the pre-segment of interest and the reference pre-segment is within a threshold and the distance measurement points P included in the pre-segment of interest and the distance measurement points P included in the reference pre-segment are in a vertical relationship. This embodiment also generates a composite segment on the condition that the pre-segment of interest surrounds the reference pre-segment. Furthermore, this embodiment generates a composite segment on the condition that the pre-segment of interest and the reference pre-segment consist of distance measurement points P corresponding to a moving target. This makes it possible to effectively suppress misrecognition of different targets as the same target while effectively suppressing over-subdivision of targets. Specifically, in the scenario shown in Figure 3, it becomes possible to distinguish between the rubber pole R and other vehicles V, which have different relative speeds to the vehicle itself, while suppressing over-dividing between the set of distance measuring points P corresponding to the wheel Vt and the set of distance measuring points P corresponding to the vehicle body Vb.

[0027] Specific examples of composite segment generation are explained using Figures 4 and 5. In these figures, velocity information at each of the multiple distance measurement points P is indicated by the density of hatching. Specifically, the denser the hatching, the higher the approach speed to the vehicle. For example, as shown in Figure 4, the approximate center of the wheel Vt in the height direction has a Doppler velocity similar to that of the vehicle body Vb. In contrast, the upper part of the wheel Vt in the height direction has a larger Doppler velocity than the vehicle body Vb. On the other hand, the lower part of the wheel Vt in the height direction has a smaller Doppler velocity than the vehicle body Vb. Therefore, in the situation shown in Figure 4, pre-segment generation using a clustering method similar to that of the conventional technology generates pre-segment PS corresponding to the upper part of the wheel Vt and pre-segment PS corresponding to the lower part of the wheel Vt separately from the pre-segment PS corresponding to the vehicle body Vb. Note that the distance measurement point P corresponding to the approximate center of the wheel Vt may be a separate pre-segment PS from the pre-segment PS corresponding to the vehicle body Vb, but it may be integrated with the pre-segment PS corresponding to the vehicle body Vb. In contrast, as shown in Figure 5, the pre-segment PS corresponding to the vehicle body Vb and each pre-segment PS corresponding to the wheel Vt are integrated into a single segment SG, or composite segment.

[0028] However, Doppler velocity may be observed in trees, for example. Therefore, a misrecognition scenario is conceivable, such as mistakenly connecting a pedestrian below a tree with the tree. To address this, this embodiment generates a composite segment on the condition that the size of the reference presegment is within a threshold. Specifically, for example, the height of an adult pedestrian is approximately 1.8m, and a child is approximately 1.15m. On the other hand, the outer diameter of a bus or truck wheel Vt is approximately 1m. Therefore, in this embodiment, the size threshold of the reference presegment for connecting the reference presegment to the segment of interest is set to a dimension corresponding to the outer diameter of a bus or truck wheel Vt (for example, a predetermined dimension of 1m square or less). This makes it possible to effectively suppress the coupling of trees and pedestrians when incorrect velocity information is obtained from trees.

[0029] Thus, in this embodiment, when grouping objects as distance measurement points P for the same target, instead of simply grouping those with similar speeds or distances, if the surrounding relationship of the distance measurement point P suggests that they are the same target, grouping is performed even if the speeds are not similar. Such surrounding relationships refer to situations where objects exist in an overhead relationship or are surrounded horizontally, even if there is a difference in speed. Note that the upper side or surrounding side must be determined to be a moving object (for example, in the case of a vehicle, this corresponds to the vehicle body Vb).

[0030] Figure 6 is a flowchart illustrating a specific example of the processing in the pre-segment generation unit 541, i.e., the pre-segment generation process. Figure 7 is a flowchart illustrating a specific example of the processing in the segment generation unit 542, i.e., the segment generation process. In these figures, "S" is an abbreviation for "step". Below, specific examples of the processing in the clustering processing unit 54, i.e., the clustering process, will be explained using the flowcharts shown in Figures 6 and 7.

[0031] The processor 51 reads the target recognition program (i.e., a program including the radar signal processing program) according to this embodiment from the memory 52 and executes it to perform the pre-segment generation process shown in Figure 6. In the pre-segment generation process, first, in step 101, the processor 51 determines whether or not connection comparisons have been performed for all combinations of distance measurement points P. "Connection comparison" refers to comparing the distance measurement point information of two distance measurement points P in order to determine whether or not to group them, that is, whether or not to form a single pre-segment PS. If there are combinations of distance measurement points P for which connection comparisons have not been completed, that is, if the determination in step 101 is "NO", the processor 51 proceeds to step 102.

[0032] In step 102, the processor 51 determines whether the distance and speed difference between the two distance measurement points P selected this time are within a threshold. If the two distance measurement points P are close together and the determination in step 102 is "YES", the processor 51 executes the process in step 103 and then returns to step 101. In step 103, the processor 51 assigns the same label to the two distance measurement points P selected this time and updates the lookup table. On the other hand, if the determination in step 102 is "NO", the processor 51 returns to step 101. If the determination in step 101 is "NO" for a different combination of two distance measurement points P than last time, and the process proceeds from step 102 to step 103 again, a different label is assigned in step 103.

[0033] If the determination in step 101 is "YES", the processor 51 executes the processes in steps 104 and 105 and then terminates the presegment generation process. In step 104, the processor 51 performs labeling using a general lookup table. In step 105, the processor 51 generates presegment information. That is, one presegment PS is generated from multiple distance measurement points P that are assigned the same label. Then, information such as position, size, and velocity is assigned to each presegment PS. The presegment generation process described above is almost the same as conventional clustering or grouping methods based on position information and velocity information. For this reason, further details about such presegment generation process are omitted in this specification.

[0034] The processor 51 reads the target recognition program (i.e., the program including the radar signal processing program) according to this embodiment from the memory 52 and executes it to perform the segment generation process shown in Figure 7. In the segment generation process, first, in step 201, the processor 51 determines whether all pre-segments PS have already been selected as focus pre-segments. If the determination in step 201 is "NO", the processor 51 selects the pre-segments PS that have not yet been selected as focus pre-segments as the focus pre-segments for the current process, and then proceeds to step 202.

[0035] In step 202, the processor 51 determines whether the presegment of interest is in a moving state (i.e., whether it corresponds to a moving target). If the determination in step 202 is "NO", the processor 51 returns to step 201. If the determination in step 202 is "YES", the processor 51 proceeds to step 203. In step 203, the processor 51 determines whether all presegments PS other than the one selected as the presegment of interest have already been selected as reference segments. If the determination in step 203 is "YES", the processor 51 returns to step 201. If the determination in step 203 is "NO", the processor 51 selects a presegment PS that has not yet been selected as a reference presegment as the reference presegment for the current process, and then proceeds to step 204.

[0036] In step 204, the processor 51 determines whether the connection conditions are met. "Connection conditions" means that all of the following conditions 1 to 3 are met. First condition: The size of the reference presegment is within the threshold. Second condition: The pre-segment of interest and the reference pre-segment are in close proximity (i.e., the distance is within a threshold). Third condition: A distance measurement point P of a reference presegment exists below the distance measurement point P that constitutes the presegment of interest.

[0037] If the determination in step 204 is "YES", the processor 51 proceeds to step 205. In step 205, the processor 51 assigns the same label to the pre-segment of interest and the pre-segment of reference and updates the lookup table. In other words, the processor 51 connects the pre-segment of interest and the pre-segment of reference. On the other hand, if the determination in step 204 is "NO", the processor 51 returns to step 203. In this case, the processor 51 does not connect the pre-segment of interest and the pre-segment of reference.

[0038] If the determination in step 201 is "YES", the processor 51 executes the processes in steps 206 and 207, and then terminates the pre-segment generation process. In step 206, the processor 51 performs labeling using a general lookup table. In step 207, the processor 51 generates segment information. That is, one segment SG is generated from multiple distance measurement points P included in pre-segment PS that are assigned the same label. Then, information such as position, size, and speed is assigned to each segment SG.

[0039] According to this specific example, for instance, the connection of the pre-segment of interest and the reference pre-segment of another vehicle V as a moving target or a rubber pole R as a stationary target is determined as follows. In the following determination example, it is assumed that two pre-segments PS are recognized for the wheel Vt: the upper part above the center and the lower part below the center. <1> Focus pre-segment = vehicle body Vb: movement Reference presegment = Top of wheel Vt: Move ...Since the distance measurement point P that constitutes the pre-segment of interest is located directly below the distance measurement point P that constitutes the reference pre-segment, the two are connected. <2> Focus pre-segment = vehicle body Vb: movement Reference presegment: Lower part of wheel Vt: stationary ...Since there is no distance measurement point P that constitutes the reference presegment directly below the distance measurement point P that constitutes the presegment of interest, the two are not connected. (However, see below) <3> As shown, the lower part of wheel Vt is connected to the upper part of wheel Vt located directly above it, and as a result, it can also be integrated with the vehicle body Vb via the upper part of wheel Vt. <3> Attention pre-segment = Top of wheel Vt: movement Reference presegment = lower part of wheel Vt: stationary ...Since the distance measurement point P that constitutes the pre-segment of interest is located directly below the distance measurement point P that constitutes the reference pre-segment, the two are connected. <4> ) Note the pre-segment = upper part of wheel Vt: movement Reference presegment = Rubber pole R: stationary ...Since there is no distance measurement point P that constitutes the reference presegment directly below the distance measurement point P that constitutes the presegment of interest, the two are not connected.

[0040] (modified version) The present invention is not limited to the embodiments and examples described above. Therefore, the above embodiments, etc. can be modified as appropriate. Representative modifications are described below. In the description of the modifications below, the differences from the above embodiments, etc. will be mainly described. In addition, the same reference numerals are used for parts that are the same or equivalent to each other in the above embodiments, etc. and the modifications below. Therefore, in the description of the modifications below, with respect to components that have the same reference numerals as in the above embodiments, etc., the descriptions in the above embodiments, etc. can be appropriately referenced unless there is a technical contradiction or special additional explanation.

[0041] The present invention is not limited to the specific device configurations shown in the embodiments described above. For example, the application of the present invention is not limited to automobiles traveling on roads. Furthermore, the radar sensor 2 may have a configuration other than that of a laser radar sensor. That is, for example, the radar sensor 2 may be a millimeter-wave radar sensor.

[0042] The functional components shown in Figure 2 are merely for convenience to simplify the explanation of one embodiment of the present invention. Therefore, the illustration in Figure 2 does not mean that these functional components must be implemented as some kind of module or hardware in the target recognition device 5.

[0043] The program according to the present invention, which enables the execution of various operations, procedures, or processes as described in the above embodiments, can be downloaded or upgraded via V2X communication. V2X stands for Vehicle to X. Alternatively, such a program can be downloaded or upgraded via terminal equipment installed at the vehicle's manufacturing plant, repair shop, dealership, etc. The storage location for such a program may be a memory card, optical disk, magnetic disk, etc.

[0044] Thus, each of the above functional configurations and processes may be realized by a dedicated computer provided by configuring a processor and memory programmed to execute one or more functions embodied by a computer program. Alternatively, each of the above functional configurations and processes may be realized by a dedicated computer provided by configuring a processor by one or more dedicated hardware logic circuits. Alternatively, each of the above functional configurations and processes may be realized by one or more dedicated computers configured by a combination of a processor and memory programmed to execute one or more functions and a processor configured by one or more hardware logic circuits. Furthermore, the computer program may be stored in a computer-readable non-transitional substantial storage medium as instructions to be executed by the computer. That is, each of the above functional configurations and processes can also be represented as a computer program including procedures for realizing it, or as a non-transitional substantial storage medium storing said program.

[0045] The present invention is not limited to the specific operating modes shown in the above embodiments. That is, for example, "within the threshold" and "less than the threshold" are interchangeable. The same applies to "greater than or equal to the threshold" and "greater than the threshold". Also, in Figure 5, the multiple pre-segments PS included in the composite segment SG may be eliminated. That is, the composite segment may be formed by connecting or integrating multiple pre-segments PS. Furthermore, by not considering the velocity information of the reference pre-segment when adding the information of the reference pre-segment to the pre-segment of interest, micro-Doppler points can be accurately excluded when calculating the velocity information of the target, thereby improving the accuracy of the velocity information.

[0046] In the above embodiment, the condition for generating a composite segment from a pre-segment of interest and a reference pre-segment included the condition that the pre-segment of interest consists of a distance measurement point P corresponding to a moving target. This can be changed. That is, the condition may include, for example, that both the pre-segment of interest and the reference pre-segment consist of a distance measurement point P corresponding to a moving target. In other words, the condition that the reference pre-segment consists of a distance measurement point P corresponding to a moving target may be added as a connection condition. In this case, in Figure 7, a step is added between step 203 and step 204 to determine whether the reference pre-segment is in a moving state (i.e., whether it corresponds to a moving target). If the determination is "YES", the process proceeds to step 204; if it is "NO", the process returns to step 203. This effectively suppresses the erroneous recognition of a stationary target and a moving target as a single entity.

[0047] As shown in Figure 8, there may be cases where the vehicle body Vb does not exist above the rear wheel Vt. In such cases, since there is no pre-segment PS corresponding to the vehicle body Vb or distance measuring point P above the pre-segment PS corresponding to the rear wheel Vt, it may not be possible to suppress over-segmentation in the above embodiment.

[0048] Therefore, in such cases, it is possible to connect the wheel segments SGt with the vehicle body segment SGb using the positional relationship between the wheel segments SGt in the bird's-eye view shown in Figure 9. That is, in the bird's-eye view, if the positions of the wheels Vt are connected by straight lines in the case of a four-wheeled vehicle, it should always form a rectangle. Therefore, referring to Figure 9, when the wheel segments SGt captured by the radar sensor 2 are connected by straight lines as shown by the dashed line in the figure, they should form a right angle. Using this right-angle relationship, a connection is made between the wheel segment SGt corresponding to the front wheel Vt, where the distance measurement point P corresponding to the vehicle body Vb is located above, and the wheel segment SGt corresponding to the rear wheel Vt. As a result, the wheel segment SGt corresponding to the rear wheel Vt is also connected to the vehicle body segment SGb, thereby suppressing over-subdivision. In this case, the wheel segments SGt that are connected to each other can be interpreted as pre-segments PS.

[0049] Modifications are not limited to the examples given above. Furthermore, multiple modifications can be combined with each other. In addition, all or part of the above embodiments and all or part of the modifications can be combined with each other.

[0050] (Perspective) As will be apparent from the descriptions of embodiments and modifications above, the disclosure herein includes at least the following aspects: [Perspective 1] Radar signal processing device (5), A distance measurement point information acquisition unit (53) acquires distance measurement point information, including position information and velocity information at each of the multiple distance measurement points acquired by radar wave irradiation, A pre-segment generation unit (541) generates a pre-segment (PS) as a set of distance points by grouping a plurality of distance points based on the distance point information acquired by the distance point information acquisition unit, A segment generation unit (542) generates a composite segment as a set of distance measurement points included in the first presegment and the second presegment, based on the positional relationship between a first presegment, which is one of the multiple presegments generated by the presegment generation unit, and a second presegment, which is another of the multiple presegments. Equipped with, Radar signal processing device. [Perspective 2] The segment generation unit generates the composite segment on the condition that the first pre-segment consists of the distance measurement point corresponding to the moving target. A radar signal processing device as described in Perspective 1. [Perspective 3] The segment generation unit generates the composite segment on the condition that the distance between the first pre-segment and the second pre-segment is within a threshold and that the distance measurement point included in the first pre-segment and the distance measurement point included in the second pre-segment are in a vertical relationship. A radar signal processing device according to viewpoint 1 or 2. [Perspective 4] The segment generation unit generates the composite segment on the condition that the first pre-segment surrounds the second pre-segment. A radar signal processing device described in any one of the following three points. [Perspective 5] The segment generation unit generates the composite segment on the condition that the size of the second pre-segment is within a threshold. A radar signal processing device described in any one of the viewpoints 1 to 4. [Perspective 6] A radar signal processing method performed by a radar signal processing device (5), By irradiating with radar waves, the system acquires distance measurement point information, including position information and velocity information for each of the multiple distance measurement points. By grouping multiple distance measurement points based on the acquired distance measurement point information, a pre-segment (PS) is generated as a set of distance measurement points. Based on the positional relationship between a first pre-segment, which is one of the multiple pre-segments generated, and a second pre-segment, which is another pre-segment, a composite segment is generated as a set of distance measurement points included in the first pre-segment and the second pre-segment. Radar signal processing method. [perspective 7] The composite segment is generated on the condition that the first pre-segment consists of the distance measurement point corresponding to the moving target. The radar signal processing method described in perspective 6. [Perspective 8] The composite segment is generated under the conditions that the distance between the first pre-segment and the second pre-segment is within a threshold and the distance measurement point included in the first pre-segment and the distance measurement point included in the second pre-segment are in a vertical relationship. A radar signal processing method as described in viewpoint 6 or 7. [Perspective 9] The composite segment is generated on the condition that the first pre-segment surrounds the second pre-segment. A radar signal processing method described in any one of viewpoints 6 to 8. [Perspective 10] The composite segment is generated on the condition that the size of the second pre-segment is within a threshold. A radar signal processing method described in any one of viewpoints 6 to 9. [Perspective 11] A radar signal processing program executed by the radar signal processing device (5), A process for acquiring distance measurement point information, including position information and velocity information, for each of the multiple distance measurement points acquired by radar wave irradiation, A process to generate a presegment (PS) as a set of distance points by grouping multiple distance points based on the acquired distance point information, A process to generate a composite segment as a set of distance measurement points included in the first presegment and the second presegment, based on the positional relationship between a first presegment, which is one of the multiple presegments generated, and a second presegment, which is another one; including, Radar signal processing program. [Perspective 12] The composite segment is generated on the condition that the first pre-segment consists of the distance measurement point corresponding to the moving target. The radar signal processing program described in perspective 11. [Perspective 13] The composite segment is generated under the conditions that the distance between the first pre-segment and the second pre-segment is within a threshold and the distance measurement point included in the first pre-segment and the distance measurement point included in the second pre-segment are in a vertical relationship. A radar signal processing program as described in perspective 11 or 12. [Perspective 14] The composite segment is generated on the condition that the first pre-segment surrounds the second pre-segment. A radar signal processing program described in any one of the following perspectives 11-13. [Perspective 15] The composite segment is generated on the condition that the size of the second pre-segment is within a threshold. A radar signal processing program described in any one of the following perspectives 11-14. [Explanation of Symbols]

[0051] 1. In-vehicle systems 2 Radar sensors 3. Vehicle speed sensor 5. Target Recognition Device (Radar Signal Processing Device) 51 processors 52 memory 53 Focus point information acquisition section 54 Clustering Processing Unit 541 Pre-segment generation unit 542 Segment generation unit

Claims

1. Radar signal processing device (5), A distance measurement point information acquisition unit (53) acquires distance measurement point information, including position information and velocity information at each of the multiple distance measurement points acquired by radar wave irradiation, A pre-segment generation unit (541) generates a pre-segment (PS) as a set of distance points by grouping a plurality of distance points based on the distance point information acquired by the distance point information acquisition unit, A segment generation unit (542) generates a composite segment as a set of distance measurement points included in the first presegment and the second presegment, based on the positional relationship between a first presegment, which is one of the plurality of presegments generated by the presegment generation unit, and a second presegment, which is another of the plurality of presegments. Equipped with, The segment generation unit generates the composite segment on the condition that the distance between the first pre-segment and the second pre-segment is within a threshold and that one of the distance measurement points included in the first pre-segment and the distance measurement point included in the second pre-segment is located above the other. Radar signal processing device.

2. The segment generation unit generates the composite segment on the condition that the first pre-segment consists of the distance measurement point corresponding to the moving target. The radar signal processing device according to claim 1.

3. The segment generation unit generates the composite segment on the condition that the size of the second pre-segment is within a threshold. The radar signal processing device according to claim 1 or 2.

4. A radar signal processing program executed by the radar signal processing device (5), A process for acquiring distance measurement point information, including position information and velocity information, for each of the multiple distance measurement points acquired by radar wave irradiation, A process to generate a presegment (PS) as a set of distance points by grouping a plurality of distance points based on the acquired distance point information, A process to generate a composite segment as a set of distance measurement points included in the first presegment and the second presegment, based on the positional relationship between a first presegment, which is one of the multiple presegments generated, and a second presegment, which is another one; Includes, The composite segment is generated under the condition that the distance between the first pre-segment and the second pre-segment is within a threshold and that one of the distance measurement points included in the first pre-segment and the distance measurement point included in the second pre-segment is located above the other. Radar signal processing program.

5. The composite segment is generated on the condition that the first pre-segment consists of the distance measurement point corresponding to the moving target. The radar signal processing program according to claim 4.

6. The composite segment is generated on the condition that the size of the second pre-segment is within a threshold. The radar signal processing program according to claim 4 or 5.

Images