Radio wave sensor, management terminal, sensing method, and computer program

Abstract

The radio wave sensor of the present disclosure performs sensing using radio waves. This radio wave sensor is provided with: a transmission / reception unit that transmits radio waves and receives radio waves; and a processor that, on the basis of the transmitted radio waves and the received radio waves, generates sensing results that include the position and the velocity of a target and outputs communication frames that include a storage field for the sensing results. The storage field includes a field that stores reliability data indicating the probability of the target being a pedestrian crossing a crosswalk.

Description

Radio wave sensor, management terminal, detection method, and computer program

[0001] The present disclosure relates to a radio wave sensor, a management terminal, a detection method, and a computer program. This application claims priority based on Japanese Application No. 2024-163461 filed on September 20, 2024, and incorporates all the descriptions described in the above Japanese application.

[0002] Patent Document 1 describes a radio wave sensor including a transmission unit, a reception unit, a calculation unit, and a setting unit. The transmission unit transmits radio waves to a target area including a crosswalk. The reception unit receives the reflected wave of the radio wave. The calculation unit calculates the direction from the radio wave sensor to an object and the distance between the radio wave sensor and the object based on the transmitted radio wave and the received reflected wave. The setting unit sets a plurality of sub-areas in the target area based on the calculated direction and distance.

[0003] Japanese Unexamined Patent Application Publication No. 2017-090078

[0004] The radio wave sensor of the present disclosure is a radio wave sensor that senses using radio waves. The radio wave sensor of the present disclosure includes a transmission / reception unit that transmits and receives the radio waves, and a processor that generates a detection result including the position and speed of a target based on the transmitted radio wave and the received radio wave, and outputs a communication frame including a storage field for the detection result. The storage field includes a field for storing reliability data representing the accuracy that the target is a pedestrian passing through a crosswalk.

[0005] Figure 1 is a perspective view showing an example of an intersection where radio wave sensors are installed. Figure 2 is a road plan showing an example of the detection area of ​​the radio wave sensors. Figure 3 is a block diagram showing an example of the hardware of the radio wave sensors. Figure 4 is a block diagram showing an example of the hardware of the management terminal. Figure 5 is a block diagram showing an example of the hardware of the signal controller. Figure 6 is a flowchart showing an example of the detection process by the radio wave sensors. Figure 7 is a flowchart showing an example of the first generation process of confidence data. Figure 8 is a flowchart showing an example of the second generation process of confidence data. Figure 9 is a flowchart showing an example of the third generation process of confidence data. Figure 10 is an explanatory diagram showing an example of the data structure of a communication frame. Figure 11 is a table showing an example of the contents of target data (TLV2).

[0006] The infrastructure-type radio wave sensor described in Patent Document 1 detects objects based on the reflection intensity of radio waves. In Patent Document 1, for example, a target moving inside a crosswalk does not notify an external device whether or not it is a pedestrian crossing the crosswalk. In view of the above problems, this disclosure aims to provide a radio wave sensor that can notify an external device whether or not the detected target is a pedestrian crossing the crosswalk. In this disclosure, pedestrians include people walking alone or with others, and people walking while pushing a stroller, and further include people moving on bicycles, kick scooters or other ride-on mobility devices, and people moving in wheelchairs.

[0007] The radio wave sensor of this disclosure can notify an external device whether or not the detected target is a pedestrian crossing a crosswalk.

[0008] The embodiments of this disclosure are outlined below.

[0009] (1) The radio wave sensor of this disclosure is a radio wave sensor that senses using radio waves. The radio wave sensor comprises a transmitting and receiving unit that transmits and receives radio waves, and a processor that generates a detection result including the position and speed of a target based on the transmitted radio waves and the received radio waves, and outputs a communication frame including a storage field for the detection result. The storage field includes a field for storing confidence data that represents the degree of certainty that the target is a pedestrian crossing a crosswalk.

[0010] In the radio wave sensor of this disclosure, the storage field included in the communication frame includes a field that stores confidence data representing the degree of certainty that the target is a pedestrian crossing a crosswalk. Therefore, the radio wave sensor can notify an external device (e.g., a management terminal described later) whether or not the detected target is a pedestrian crossing a crosswalk.

[0011] (2) In the radio wave sensor described in (1) above, the processor may determine the accuracy based on the crossing distance of the target. In this way, the possibility of missing pedestrians crossing the crosswalk can be reduced compared to when both the crossing distance and the crossing time are used.

[0012] (3) In the radio wave sensor described in (1) above, the processor may determine the accuracy based on the crossing distance and crossing time of the target. In this way, the possibility of false detection can be reduced compared to using only the crossing distance, and the reliability of the accuracy determination result can be increased.

[0013] (4) In the radio wave sensors described in (1) to (3) above, the processor may determine the accuracy based on the direction of movement of the target. This improves the accuracy of distinguishing between pedestrians and vehicles crossing a crosswalk.

[0014] (5) The management terminal of the present disclosure is a management terminal that is communicatively connected to the radio wave sensors of (1) to (4) above. The management terminal of the present disclosure comprises a communication interface for receiving the communication frame, a display device that displays icons representing the crossing area and the target on the screen, and a graphics controller that causes the display device to output the icons based on the detection results included in the communication frame. The graphics controller determines the display format of the icons based on the reliability data.

[0015] According to this management terminal, the display format of the icon representing the target is determined based on the reliability data. Therefore, users such as traffic managers can recognize the credibility of the reliability data in accordance with changes in the display format of the icon.

[0016] (6) The management terminal described in (5) above may further include a processor capable of setting the reliability data generation logic to be executed by the radio wave sensor by communicating with the radio wave sensor. In this way, users such as traffic managers can use the management terminal to switch the reliability data generation logic to be executed by the radio wave sensor.

[0017] (7) The detection method of the present disclosure is a detection method performed by the radio wave sensors described in (1) to (4) above. The detection method of the present disclosure includes the steps of generating the detection result based on the transmitted radio waves and the received radio waves, and outputting the communication frame. This detection method has the same effects as the radio wave sensors described in (1) to (4) above.

[0018] (8) The computer program of this disclosure is a computer program that causes a computer to function as the processor provided in the radio wave sensors described in (1) to (4) above. This computer program has the same effects as the radio wave sensors described in (1) to (4) above.

[0019] This disclosure is also applicable to semiconductor integrated circuits that constitute part or all of the system and apparatus.

[0020] <Details of Embodiments in This Disclosure> Hereinafter, details of embodiments of the present invention will be described with reference to the drawings. At least some of the embodiments described below can be combined with other embodiments.

[0021] [Installation of radio wave sensor] As shown in Figures 1 and 2, intersection 70 is a four-way intersection where roadway 60 and roadway 65 intersect. In this embodiment, left-hand traffic roadways 60 and 65 (for example, roadways in Japan) are used as examples, but the technology disclosed in this embodiment is also applicable to right-hand traffic roadways.

[0022] The radio wave sensor 10 of this embodiment is a sensor that senses objects using radio waves. Specifically, the radio wave sensor 10 is a millimeter-wave radar. The radio wave sensor 10 may be remotely controlled. The frequency of the radio waves is, for example, 24 GHz, 60 GHz, 76 GHz, or 79 GHz. The radio wave sensor 10 may be a "mobile" radio wave sensor mounted on a moving object such as a vehicle, or it may be an "infrastructure" radio wave sensor installed on a road structure 50.

[0023] The radio wave sensor 10 is a radio wave radar that detects objects (e.g., pedestrians or vehicles) located in the detection area 30. The radio wave sensor 10 may also be a radio wave radar for traffic monitoring. The detection area 30 is an area on a road. In this disclosure, “road” includes roadways and sidewalks. The radio wave sensor 10 is mounted on a structure 50. Therefore, in this embodiment, the radio wave sensor 10 is an infrastructure-type radio wave sensor.

[0024] The structure 50 includes a pole 51 and an arm 52 protruding from the top of the pole 51. A radio wave sensor 10 is attached to the arm 52. The radio wave sensor 10 is installed at a height of several meters above the ground. The radio wave sensor 10 emits radio waves (millimeter waves) from a height of several meters above the ground toward the crosswalk 20 and detects pedestrians on the crosswalk 20 by receiving the reflected waves.

[0025] Specifically, the radio wave sensor 10 detects the distance to an object, the horizontal angle of the object, and the velocity of the object. The distance to the object is the distance from the antenna of the radio wave sensor 10 to the object. The horizontal angle of the object is the horizontal angle formed by the direction from the antenna of the radio wave sensor 10 toward the object and a predetermined reference direction. The horizontal angle is also called the "azimuth angle." The predetermined reference direction is, for example, the normal direction of the radio wave irradiation surface of the radio wave sensor 10. The radio wave irradiation surface is the surface from which radio waves are generated.

[0026] In this embodiment, a detection area 30 is defined. The detection area 30 is an area on the road where the radio wave sensor 10 can detect objects. The detection area 30 is included in the radio wave irradiation area 40. In other words, the radio wave irradiation area 40 covers the entire detection area 30. To monitor traffic conditions at the pedestrian crossing 20, the detection area 30 typically includes the pedestrian crossing 20.

[0027] The radio wave sensor 10 emits radio waves, which are reflected by an object. The radio wave sensor 10 then detects the object based on the reflected waves from the object. In this embodiment, the radio wave sensor 10 can detect objects located within the radio wave irradiation area 40, and the radio wave irradiation area 40 does not include any area where the radio wave sensor 10 cannot detect an object. The radio wave irradiation area 40 may be the entire area to which the radio wave sensor 10 can emit radio waves. In other words, the radio wave irradiation area 40 may include areas where the radio wave sensor 10 can detect an object and areas where the radio wave sensor 10 cannot detect an object. The detection area 30 is included in the area where the radio wave sensor 10 can detect an object.

[0028] The pedestrian crossing 20 is located on the roadway 60 near the intersection 70. Intersection 70 in Figure 1 is the point where roadway 60 and roadway 65 intersect. Sidewalks 63a and 63b are provided on both sides of roadway 60, and sidewalks 63a and 63b are adjacent to roadway 60. Roadway 60 includes on-road lanes 61a and 61b through which vehicles enter intersection 70, and off-road lanes 62a and 62b through which vehicles exit intersection 70.

[0029] The entry lane 61a is for going straight and turning left. Vehicles traveling in the entry lane 61a in the x1 direction shown in Figure 1 can either go straight through intersection 70 or turn left (changing their direction of travel to the y1 direction shown in Figure 1) to enter the roadway 65. The entry lane 61b is for going straight and turning right. Vehicles traveling in the entry lane 61b in the x1 direction shown in Figure 1 can either go straight through intersection 70 or turn right (changing their direction of travel to the y2 direction shown in Figure 1) to enter the roadway 65.

[0030] Vehicles traveling straight along the roadway 60 in the x2 direction shown in Figure 1 and passing through intersection 70, vehicles traveling along the roadway 65 in the y1 direction shown in Figure 1 and turning left at intersection 70, and vehicles traveling along the roadway 65 in the y2 direction and turning right at intersection 70 enter exit lane 62a. Vehicles traveling straight along the roadway 60 in the x2 direction shown in Figure 1 and passing through intersection 70, vehicles traveling along the roadway 65 in the y2 direction shown in Figure 1 and turning right at intersection 70, and vehicles traveling along the roadway 65 in direction y1 and turning left in direction x2 enter exit lane 62b.

[0031] As shown in Figure 1, a vehicle signal light 1 and a pedestrian signal light 2 are installed at intersection 70. The vehicle signal light 1 indicates to vehicles traveling on roadways 60 and 65 whether they are permitted to pass through intersection 70. The pedestrian signal light 2 indicates to pedestrians whether they are permitted to cross the crosswalk 20. A signal controller 300 is also installed at intersection 70. The signal controller 300 supplies power to the vehicle signal light 1 and the pedestrian signal light 2 and determines the timing for changing the light colors of the vehicle signal light 1 and the pedestrian signal light 2. The hardware of the signal controller 300 will be described later.

[0032] [Radio wave sensor detection area] As shown in Figure 2, the detection area 30 includes the zebra area 31 and the waiting areas 32a and 32b. The zebra area 31 is the area where pedestrians pass, and includes the crosswalk. The zebra area 31 is the area enclosed by the dotted line in Figure 2. In Figure 2, the crosswalk has a zebra pattern, but the crosswalk does not have to have a zebra pattern. The waiting areas 32a and 32b are areas where pedestrians wait to pass, and are provided at both ends of the detection area 30 along the longitudinal axis. In Figure 2, the waiting area 32a is located within the sidewalk 63a, and the waiting area 32b is located within the sidewalk 63b.

[0033] At intersection 70, arc-shaped corner cuts 61c and 62c are provided at the connection points between roadway 60 and roadway 65. Specifically, corner cut 61c is provided at the connection point between the incoming lane 61a and roadway 65, and corner cut 62c is provided at the connection point between the outgoing lane 62a and roadway 65.

[0034] [Coordinate System of Radio Wave Sensor] In this embodiment, the position of an object is specified in both a "polar coordinate system" and a "plane coordinate system". In the polar coordinate system, the position of an object is expressed by the distance from the antenna 106a of the radio wave sensor 10 and the azimuth angle of the object as seen from the antenna 106a of the radio wave sensor 10. The reference line for the azimuth angle (the line corresponding to an angle of 0°) is the line of intersection between the vertical plane containing the radio wave irradiation axis of the radio wave sensor 10 (the normal to the radio wave irradiation surface of the radio wave sensor 10) and the ground. The vertical plane is a plane perpendicular to the ground. Hereinafter, the position specified by the distance and azimuth angle in the polar coordinate system will be referred to as the "polar position".

[0035] In a planar coordinate system, the position of an object is represented by the coordinates formed by two mutually orthogonal horizontal axes (X-axis and Y-axis) of the ground (earth surface). The origin P of the planar coordinate system is the position vertically below the radio wave sensor 10, that is, the installation position of the radio wave sensor 10. The Y-axis is the line of intersection between the vertical plane containing the radio wave irradiation axis of the radio wave sensor 10 (the normal to the radio wave irradiation surface of the radio wave sensor 10) and the ground. The Y-axis is the same as the reference line described above. Hereinafter, the position specified by the X and Y coordinate values ​​of the planar coordinate system will be referred to as the "planar position".

[0036] The radio wave sensor 10 is installed so that its reference line (Y-axis) is parallel to the direction of travel of the pedestrian crossing 20. The outer edge data 111 of the detection area 30 and the outer edge data 112 of the zebra area 31 are pre-registered in the radio wave sensor 10. The outer edge data 111 and outer edge data 112 are defined in planar position. The position of the detected object is output in planar position data format. For example, the detection area 30 is set by a traffic manager using a management terminal 200 such as a notebook PC that is connected to the radio wave sensor 10 in a communicative manner.

[0037] [Radio Wave Sensor Hardware] As shown in Figure 3, the radio wave sensor 10 includes, for example, a processor 101, a non-volatile memory 102, a volatile memory 103, a transmitting / receiving unit 104, and a communication interface (I / F) 107.

[0038] The volatile memory 103 is a semiconductor memory such as SRAM (Static Random Access Memory) or DRAM (Dynamic Random Access Memory). The non-volatile memory 102 is, for example, flash memory, a hard disk, or ROM (Read Only Memory). The non-volatile memory 102 stores the outer edge data 111 and the outer edge data 112.

[0039] Outer edge data 111 represents the planar position of the outer edge of the detection area 30. For example, if the detection area 30 is a rectangle, the planar positions of the four vertices of the rectangle are the outer edge data 111. Outer edge data 112 represents the planar position of the outer edge of the zebra area 31. For example, if the zebra area 31 is a rectangle, the planar positions of the four vertices of the rectangle are the outer edge data 112.

[0040] The non-volatile memory 102 stores the control program 110 and the data used to execute it. The radio wave sensor 10 functions when the processor 101 executes the control program 110. The control program 110 is stored in a recording medium such as flash memory, ROM, or CD-ROM. The control program 110 includes a computer program that causes the processor 101 to execute the detection process described later.

[0041] The processor 101 is, for example, a CPU (Central Processing Unit). However, the processor 101 is not limited to a CPU. The processor 101 may also be a GPU (Graphics Processing Unit). The processor 101 may also be, for example, an ASIC (Application Specific Integrated Circuit), or a programmable logic device such as a gate array or FPGA (Field Programmable Gate Array).

[0042] The transmitting / receiving unit 104 includes a transmitting circuit 105 and a receiving circuit 106. The transmitting circuit 105 includes a transmitting antenna 105a. In Figure 3, the transmitting circuit 105 includes one transmitting antenna 105a, but the transmitting circuit 105 may include two or more transmitting antennas 105a. The transmitting circuit 105 generates a modulated wave (radio wave) of a predetermined frequency and transmits the modulated wave from the transmitting antenna 105a. In this embodiment, the radio wave radar is an FMCW radar (Frequency Modulated Continuous Wave radar), and the modulated wave is generated based on a chirp signal. When the transmitted modulated wave strikes an object (e.g., a pedestrian or a vehicle), a portion of the modulated wave is reflected and becomes a reflected wave. The chirp signal is considered a modulated wave signal, and an intermediate frequency signal is generated by the interaction between the modulated wave and the reflected wave. Hereinafter, the intermediate frequency signal will be referred to as the "IF signal".

[0043] The receiving circuit 106 includes two or more receiving antennas 106a to detect the azimuth angle of an object. In Figure 3, the receiving circuit 106 is equipped with four receiving antennas 106a. The receiving circuit 106 performs signal processing on the received reflected wave to generate reflected wave data. The reflected wave data is transmitted to the processor 101. The processor 101 analyzes the reflected wave data and detects the position and velocity of the object. The position of the object is expressed by the distance to the object and the azimuth angle.

[0044] The communication interface 107 is a communication module for communicating with an external device. The external device is, for example, at least one of the management terminal 200 and the signal controller 300. The communication method between the communication interface 107 and the external device may be either wired or wireless, or may be a method via a network. The communication interface 107 transmits, for example, data on the detection result to the management terminal 200 and the signal controller 300. The communication interface 107 receives the outer edge data 111 generated by the management terminal 200 from the management terminal 200.

[0045] [Hardware of the Management Terminal] The management terminal 200 is a terminal device used, for example, for setting the detection area 30 and displaying the detection result. As shown in FIG. 4, the management terminal 200 includes a processor 201, a non-volatile memory 202, a volatile memory 203, an input / output interface (I / F) 204, a graphic controller 205, a communication interface (I / F) 206, an input device 211, and a display device 212.

[0046] The input device 211 and the display device 212 may be external devices that can be connected to a dedicated port attached to the housing of the management terminal 200. The volatile memory 203 is a semiconductor memory such as SRAM or DRAM, for example. The non-volatile memory 202 is a flash memory, a hard disk, or a ROM, for example.

[0047] The non-volatile memory 202 stores the control program 210 and the data used for its execution. By the processor 201 executing the control program 210, the management terminal 200 functions. The control program 210 is stored in a recording medium such as a flash memory, a ROM, or a CD-ROM. The control program 210 includes a computer program. The computer program causes the processor 101 or the graphic controller 205 to execute, for example, the following processes.

[0048] "Position setting" is a process for setting the planar positions of areas 30 and 31. The position setting is executed by the processor 101. The planar positions of areas 30 and 31 are represented by outer edge data 111 and 112 respectively. "Reliability setting" is a process for setting the generation logic and threshold values of reliability data. Details of the reliability data will be described later. The reliability setting is executed by the processor 101. "Image processing" is an image processing for superimposing the detection result of the radio wave sensor 10 on a digital video. The detection result is, for example, the position of an object. The image processing is executed by the graphic controller 205.

[0049] The processor 201 is, for example, a CPU. The processor 201 is not limited to a CPU. The processor 201 may be a GPU. The processor 201 may be, for example, an ASIC, or a programmable logic device such as a gate array or an FPGA.

[0050] The input device 211 includes pointing devices such as a keyboard and a mouse. The input device 211 may be a capacitive or pressure-sensitive touch pad superimposed on the screen of the display device 212. The input device 211 is used for input operations to the management terminal 200. The input / output interface 204 is connected to the input device 211. The input / output interface 204 receives input data from the input device 211 and transmits the received data to the processor 201.

[0051] The display device 212 includes, for example, a liquid crystal panel or an OEL (organic electroluminescence) panel. The display device 212 can display characters, graphics, or digital videos. The graphic controller 205 is connected to the display device 212 and controls the display on the display device 212. The graphic controller 205 includes, for example, a GPU and VRAM (Video RAM). The graphic controller 205 holds the data to be displayed on the display device 212 in VRAM, periodically reads out video data for one frame from VRAM, and generates a video signal.

[0052] The video signal is output to the display device 212, and the video is displayed on the display device 212. The processor 201 may also have the functionality of a graphics controller 205. A portion of the volatile memory 203 may be used as VRAM. The graphics controller 205 can synthesize digital images. The graphics controller 205 superimposes predetermined icons onto the captured video, for example, the pedestrian crossing 20. The captured video is captured by a surveillance camera (not shown). The display device 212 outputs the generated composite image.

[0053] The communication interface 206 is a communication module for communicating with an external device (e.g., a radio wave sensor 10). The communication method between the communication interface 206 and the external device may be wired, wireless, or via a network. The communication interface 206 transmits the outer edge data 111 and 112 generated by the processor 101 during the setup process to the radio wave sensor 10. The communication interface 206 receives detection result data from the radio wave sensor 10.

[0054] [Signal Controller Hardware] As shown in Figure 5, the signal controller 300 comprises a control unit 301, a storage unit 302, a communication interface (I / F) 303, and a lamp drive unit 304. The control unit 301 is connected to the storage unit 302, the communication interface 303, and the lamp drive unit 304 via an internal bus. The control unit 301 controls the operation of these units.

[0055] The control unit 301 is an arithmetic processing unit that includes a processor such as a CPU and main memory, which is volatile memory. The control unit 301 loads the control program 305 stored in the storage unit 302 into the memory and performs information processing according to the control program 305. The storage unit 302 is composed of flash memory and non-volatile memory such as a hard disk, and stores control data for signal control and the control program 305. The control data is, for example, a display table that defines the lighting time of the vehicle signal light 1 and the lighting time of the pedestrian signal light 2 for each stage.

[0056] The communication interface 303 is a communication module for communicating with roadside sensors such as the radio wave sensor 10. The communication method between the communication interface 303 and the roadside sensors may be either wireless or wired. If the signal controller 300 is remotely controlled by a central unit at a traffic control center, the communication interface 303 is also equipped with a communication module for communicating with the central unit.

[0057] The control program 305 includes a computer program for signal control that determines the timing of turning on and off the vehicle signal lamp 1 and the pedestrian signal lamp 2. The control unit 301 determines the timing of switching the signal lamp color in one cycle based on predefined control data, such as the indication table described above, and outputs a switching signal to the lamp drive unit 304 at the determined timing.

[0058] The lamp drive unit 304 includes a semiconductor relay (not shown). The semiconductor relay of the lamp drive unit 304 turns on or off the power supplied to the lights included in the vehicle signal lamp 1 and the pedestrian signal lamp 2 according to a switching signal input from the control unit 301.

[0059] [Detection processing by radio wave sensor] The detection processing shown in Figure 6 is performed by the processor 101 of the radio wave sensor 10 at predetermined control cycles (for example, 100 milliseconds).

[0060] As shown in Figure 6, the processor 101 executes the "return wave data generation process" (step S101). This generation process includes the following processes 1 to 3.

[0061] In process 1, the modulated wave signal input from the transmitting circuit 105 and the reflected wave signal input from the receiving circuit 106 are combined to generate an IF signal. In process 2, the IF signal is subjected to a Fast Fourier Transform (FFT) to calculate the polar position (distance and azimuth angle) of the reflected wave. In process 3, reflected wave data is generated based on the calculated polar position. The reflected wave data includes waveform data related to distance and waveform data related to azimuth angle.

[0062] The processor 101 performs the "object position and velocity determination process" (step S102). This determination process includes the following processes 4 to 6.

[0063] In process 4, points in the reflected wave waveform data where the waveform height exceeds a predetermined value are identified as specific points corresponding to an object. In this disclosure, specific points may be considered as objects. For this reason, below, for example, "position of the object" may be written as "position of the specific point," and "velocity of the object" may be written as "velocity of the specific point." In process 5, the planar position (X coordinate value and Y coordinate value) is calculated based on the polar position of the specific point. The calculated planar position is the position of the specific point. In process 6, the velocity of the specific point is calculated based on multiple IF signals. Each IF signal corresponds to each of the multiple chirp signals.

[0064] The processor 101 performs the "object tracking process" (step S103). This tracking process includes the following processes 7 and 8.

[0065] In process 7, if a specific point that appeared in the current cycle was not detected in the previous cycle, identification data (ID) is assigned to that specific point in the current cycle. Hereafter, a specific point (object) that has been assigned an ID and is being tracked will also be called a "target". In process 8, if the specific point that appeared in the current cycle had its position identified in the previous cycle, the specific point that appeared in the current cycle will carry over the identification data from the previous cycle. Whether or not the specific point in the current cycle is the same as the specific point in the previous cycle is determined by an estimation process using the direction of movement and velocity.

[0066] The processor 101 performs the "reliability data generation process" (step S104). The "reliability data" represents the degree of certainty that the target is a pedestrian crossing the crosswalk using predetermined identification data. Hereinafter, a pedestrian crossing the crosswalk will be referred to as a "crosswalk pedestrian," and the degree of certainty that the target is a pedestrian crossing the crosswalk will also be simply referred to as "certainty." In this embodiment, two numerical values ​​(1 and 0) are used as the identification data for certainty. "Reliability data = 1" indicates a high degree of certainty, and "reliability data = 0" indicates a low degree of certainty or a certainty of zero. Certainty may be represented by three or more values.

[0067] In the following, "certainty" may be expressed as "reliability." High certainty means "reliable," and low certainty means "unreliable."

[0068] The processor 101 performs "output processing of detection results" (step S105). In this output processing, the processor 101 generates a communication frame containing the detection results and has the generated communication frame sent to the communication interface 107. The data structure of the communication frame will be described later. The destination of the communication frame includes, for example, at least one of the management terminal 200 and the signal controller 300.

[0069] The detection result of the radio wave sensor 10 includes "target data". In the target data, specific points are represented as points. In this embodiment, the target data includes, for example, the following data 1 to data 5.

[0070] Data 1 is the target's position (e.g., X and Y coordinate values). Data 2 is the target's speed on the road. The unit of speed is, for example, "m / s". Data 3 is the target's identification data (e.g., identification number or identification value). Data 4 is the time the target was identified, i.e., the time the ID was assigned. The time can be expressed as absolute or relative time. Data 5 is the target's confidence level data (e.g., "1" or "0"). Speed ​​can be calculated by dividing the distance between the positions at two measurement times by the difference between the two measurement times, so either Data 2 or Data 4 may be omitted.

[0071] [First Generation Process for Confidence Data] Hereinafter, the first generation process for confidence data will be abbreviated as "Generation Process 1". The meanings of the reference numerals and parameters in Figure 7 are as follows.

[0072] TG is a specific point, i.e., the target, to which an ID has been assigned and which is the target of tracking. CD is the cross-sectional distance of the target. The cross-sectional distance CD is the distance the target has moved along the Y-axis from the start time of target tracking to the measurement time. In this embodiment, the start time of target tracking is t0. ThD is the distance threshold for accuracy determination. In this embodiment, ThD is 3m.

[0073] RD is confidence data. In this embodiment, RD = 1 represents "reliable" and RD = 0 represents "unreliable". AR is the pedestrian crossing area. The crossing area AR is, for example, the area inside the zebra area 31.

[0074] (Contents of generation process 1) As shown in Figure 7, the processor 101 determines whether the target TG is located within the crossing area AR (step S201). If the target TG is located within the crossing area AR, the processor 101 calculates the crossing distance CD at the measurement time (step S202). If the tracking start time of the target TG is "t0" and the measurement time is "t1", the difference between the Y coordinate value at time t0 and the Y coordinate value at time t1 is the crossing distance CD.

[0075] The processor 101 determines whether the inequality "CD ≥ ThD" holds true (step S203). If the above inequality holds true, the processor 101 determines the value of the confidence data RD to be "1" (step S204), and if the above inequality does not hold true, it determines the value of the confidence data RD to be "0" (S205).

[0076] (Display format of display screen example 1) The lower part of Figure 7 is an example of a display screen for the target TG including the confidence data RD determined by the generation process 1 (hereinafter referred to as "display screen example 1"). Display screen example 1 is a planar image of the XY coordinate system and is displayed on the display device 212 of the management terminal 200. The planar image includes a rectangular icon representing the outer edge shape of the cross-sectional area AR and a circular dot icon representing the planar position of the target TG.

[0077] The graphics controller 205 receives a communication frame from the radio wave sensor 10 and extracts target data from the communication frame. The graphics controller 205 controls the display device 212 so that a dot icon is displayed at the pixel position corresponding to the planar position of the target data. Display screen example 1 shows the position of the target TG at each time. The tracking start time of the target TG is t0, and the elapsed time is in the order of times t0, t1, t2, t3, and t4.

[0078] The graphics controller 205 changes the display format of the dot icon of the target TG according to the content of the confidence data RD, specifically whether the confidence data RD is 1 or 0. For example, the graphics controller 205 controls the display device 212 so that when "RD = 0", the dot icon becomes a black dot icon, and when "RD = 1", the dot icon becomes a white dot icon.

[0079] The graphics controller 205 connects an arrow icon to the dot icon of the target TG. The direction of the arrow in the arrow icon represents the direction of movement of the target TG at the measurement time, and the length of the arrow icon represents the speed of movement of the target TG at the measurement time.

[0080] (Temporal changes in display screen example 1) In display screen example 1, at time t1, the crossing distance CD is 1m, i.e., crossing distance CD < ThD, so RD = 0 and the target TG is displayed as a black dot icon. At time t2, the crossing distance CD is 3m, i.e., crossing distance CD ≥ ThD, so RD = 1 and the target TG is displayed as a white dot icon. At times t3 and t4, the crossing distance CD ≥ ThD, so RD = 1 and the target TG is displayed as a white dot icon.

[0081] [Second Generation Process for Confidence Data] Hereinafter, the second generation process for confidence data will be abbreviated as "Generation Process 2". The meanings of the reference symbols and parameters in Figure 8 are as follows (excluding those already defined in Figure 7).

[0082] CT is the crossing time of the target TG. The crossing time CT is the time elapsed from the start time of tracking the target TG (for example, t0 in Figure 8). ThT is the time threshold for accuracy determination. In this embodiment, ThT is 3 seconds.

[0083] (Contents of generation process 2) As shown in Figure 8, the processor 101 of the radio wave sensor 10 determines whether the target TG is located within the crossing area AR (step S301). If the target TG is located within the crossing area AR, the crossing distance CD and crossing time CT at the measurement time are calculated (step S302). If the tracking start time of the target TG is "t0" and the measurement time is "t1", the distance between the Y coordinate value at time t0 and the Y coordinate value at time t1 is the crossing distance CD, and t1 - t0 is the crossing time CT.

[0084] The processor 101 determines whether the inequalities "CD≧ThD" and "CT≧ThT" are true (step S303). If both of the above two inequalities are true, the processor 101 determines the value of the confidence data RD to be "1" (step S304). If neither of the above two inequalities is true, the processor 101 determines the value of the confidence data RD to be "0" (S305).

[0085] (Display format of display screen example 2) The lower part of Figure 8 is an example of the display screen of the target TG (hereinafter referred to as "display screen example 2"). Display screen example 2 includes confidence data RD determined by generation process 2. The representation format of display screen example 2 is the same as the display format of display screen example 1, so a detailed explanation of display screen example 2 is omitted. In display screen example 2, time t1 is 1 second after time t0, time t2 is 2 seconds after time t0, time t3 is 3 seconds after time t0, and time t4 is 4 seconds after time t0.

[0086] (Temporal changes in display screen example 2) In display screen example 2, at time t1, the crossing distance CD is 1m, i.e., crossing distance CD < ThD, so RD = 0 and the target TG is displayed as a black dot icon. At time t2, the crossing distance CD is 3m, i.e., crossing distance CD ≥ ThD. However, the crossing time T is 2 seconds, i.e., crossing time T < ThT, so RD = 0 and the target TG is displayed as a black dot icon.

[0087] At time t3, the crossing distance CD is 4m, i.e., crossing distance CD ≥ ThD, and the crossing time CT is 3 seconds, i.e., crossing distance CD ≥ ThT, so RD = 1 is determined, and the target TG is displayed as a white dot icon. At time t4, CD ≥ ThD and CT ≥ ThT, so RD = 1 is determined, and the target TG is displayed as a white dot icon.

[0088] [Third Generation Process for Confidence Data] Hereinafter, the third generation process for confidence data will be abbreviated as "generation process 3". The meanings of the reference symbols and parameters in Figure 9 are as follows (excluding those already defined in Figure 7).

[0089] VS is a vector representing the direction of movement of the target TG. The length of vector VS is not limited. In this embodiment, vector VS is a unit vector. VY is a vector representing the Y-axis direction. The length of vector VY is not limited. In this embodiment, vector VY is a unit vector. ThI is the dot product threshold for accuracy determination.

[0090] (Contents of generation process 3) As shown in Figure 9, the processor 101 determines whether the target TG being tracked is located within the cross-sectional area AR (step S401). If the target TG is located within the cross-sectional area AR, the processor 101 calculates the ABS "VS・VY" at the measurement time (step S402). "ABS()" is a function that returns the absolute value of the number in parentheses ( ). "VS・VY" is the dot product of vector VS and vector VY. The larger ABS(VS・VY) is, the more the direction of VS is aligned with the Y axis.

[0091] The processor 101 determines whether the inequality "ABS(VS・VY)≧ThI" holds true (step S203). If the above inequality holds true, the processor 101 determines the value of the confidence data RD to be "1" (step S404). If the above inequality does not hold true, the processor 101 determines the value of the confidence data RD to be "0" (S405).

[0092] (Display format of display screen example 3) The lower part of Figure 9 is an example of the display screen of the target TG (hereinafter referred to as "display screen example 3"). Display screen example 3 includes confidence data RD determined by generation process 3. The representation format of display screen example 3 is the same as the display format of display screen example 1, so a detailed explanation of display screen example 3 is omitted.

[0093] In display screen example 3, at time t1 and time t2, ABS(VS・VY) < ThI. At time t3 and time t4, ABS(VS・VY) ≥ ThI.

[0094] (Temporal changes in display screen example 3) In display screen example 3, at times t1 and t2, ABS(VS・VY) < ThI, so RD = 0, and the target TG is displayed as a black dot icon. At time t3, ABS(VS・VY) ≥ ThI, so RD = 1, and the target TG is displayed as a white dot icon. At time t4, vector VS coincides with vector VY, meaning the angle between vector VS and vector VY is 0°. At time t4 as well, ABS(VS・VY) ≥ ThI, so RD = 1, and the target TG is displayed as a white dot icon.

[0095] [Reliability Setting] The control program 110 includes a computer program for reliability setting. In reliability setting, the generation logic and thresholds for reliability data RD are set. Reliability setting includes selecting the generation logic for reliability data RD and setting the thresholds ThD, ThT, and ThI used in the generation logic. The generation logic for reliability data RD is, for example, one of generation processes 1 to 3.

[0096] Specifically, for example, when a traffic manager operates the input device 211 to call up the reliability setting tool, the setting screen of the setting tool is displayed on the display device 212. This enables the management terminal 200 to communicate with the radio wave sensor 10. The setting screen includes a tab for selecting the generation logic. When one of generation processes 1 to 3 is entered into the selection tab, the processor 101 switches the generation logic of the reliability data RD in the control program 110 for the detection process to the entered logic.

[0097] The settings screen includes input tabs for thresholds ThD, ThT, and ThI. When numerical values ​​are entered into the input tabs, the processor 101 switches the values ​​of the thresholds ThD, ThT, and ThI for determining the confidence data RD to the entered numerical values.

[0098] In generation process 1 (see Figure 7), the accuracy (confidence level) is determined based solely on the cross-sectional distance CD, that is, based solely on the comparison result between the cross-sectional distance CD and the distance threshold ThD. In generation process 2 (see Figure 8), the accuracy (confidence level) is determined based on the cross-sectional distance CD and the cross-sectional time CT, that is, in addition to the comparison result between the cross-sectional distance CD and the distance threshold ThD, the comparison result between the cross-sectional time CT and the time threshold ThT. Generation processes 1 and 2 have the following advantages and disadvantages.

[0099] In generation process 1, the reliability is more likely to be "reliable" than in generation process 2, and pedestrians crossing the street are less likely to be missed than in generation process 2 (advantages of generation process 1). However, in generation process 1, the possibility of false detection is higher than in generation process 2, and the reliability of the accuracy judgment result in generation process 1 is lower than in generation process 2 (disadvantages of generation process 1).

[0100] In generation process 2, the reliability is more likely to be "unreliable" than in generation process 1, and pedestrians crossing the road are more likely to be missed than in generation process 1 (disadvantage of generation process 2). In generation process 2, the possibility of false detection is lower than in generation process 1, and the reliability of the accuracy judgment result in generation process 2 is higher than in generation process 1 (advantage of generation process 2).

[0101] Traffic managers may choose either generation process 1 or generation process 2 depending on the situation in which the radio wave sensor 10 is used. For example, if the green light duration of the pedestrian signal light 2 is extended in response to the detection of a pedestrian crossing, generation process 2 may be adopted. This is because if there are many false detections of pedestrians crossing, the green light duration of the vehicle signal light 1 will become unnecessarily short. If the system is to notify vehicles attempting to pass through intersection 70 that a pedestrian is located at intersection 70, generation process 1 may be adopted. This is to make it less likely to miss a pedestrian crossing and to prevent accidents.

[0102] In generation process 3, the confidence level is determined using the vector VS. Therefore, the accuracy of generation process 3 in distinguishing between pedestrians and vehicles is higher than that of generation processes 1 and 2. Consequently, generation process 3 may be used alone. Generation processes 1 and 3 may be used in combination, and generation processes 2 and 3 may be used in combination.

[0103] When using both generation process 1 and generation process 3, a generation logic may be adopted in which RD is determined to be 1 if the inequalities "CD≧ThD" and "ABS(VS・VY)≧ThI" are true. When using both generation process 2 and generation process 3, a generation logic may be adopted in which RD is determined to be 1 if all of the following are true: "CD≧ThD", "CT≧ThT", and "ABS(VS・VY)≧ThI".

[0104] [Data structure of the communication frame] The processor 101 outputs the communication frame to the communication interface 107, and the communication frame is transmitted to an external device. As shown in Figure 10, the communication frame includes a fixed-size frame header and a body in TLV (Type Length Value) format.

[0105] For example, if the detection process stops due to an abnormality in the radio wave sensor 10, only the frame header containing an identification value indicating the equipment abnormality is sent to the external device.

[0106] The body section is composed of, for example, at least one of storage fields TLV1 and TLV2. TLV1 is a field where "static data" is stored. TLV2 is a field where "target data" is stored.

[0107] TLV1 contains a header that lists the field name and its length, and a value that lists the data value. The field name represents the data stored. The field name of TLV1 is "static data". Static data includes, for example, the identification data (ID) of the radio wave sensor 10, and the latitude and longitude of the origin of the plane coordinate system. The communication frame containing TLV1 is transmitted to the external device when the radio wave sensor 10 is started up or when it receives an information request command from the external device.

[0108] A TLV2 contains a header that lists the field name and its length, and a value that lists the data value. The field name in the TLV2 is "Target Data". The Target Data is dynamic data about the target's attributes, such as the target's location, velocity, and type. The Target Data may also be the probability that the target is a pedestrian crossing the street. A communication frame containing the TLV2 is sent to an external device each time a target is detected.

[0109] [Contents of Target Data] As shown in Figure 11, the target data includes "Target ID", "Coordinate 1", "Coordinate 2", "Speed", "Direction of Movement", "Type", "Inside / Outside Flag", "Stop Flag", "Reliability" (reliability data), and "Estimated Time of Arrival".

[0110] The "Target ID" field contains the identification value of the target TG. The "Coordinate 1" field contains the X-coordinate value of the target TG. The "Coordinate 2" field contains the Y-coordinate value of the target TG. The "Velocity" field contains the velocity of the target TG. The velocity of the target TG is, for example, the velocity at a specific moment in the current period.

[0111] The "Direction of Movement" field contains a value representing the direction of movement of the target TG. The direction of movement is expressed, for example, as the angle between the direction of movement and the Y-axis. This angle is "θ" as shown in Figure 11. The direction of movement of the target TG is, for example, the direction of movement at a specific moment in the current period.

[0112] The "Type" field contains the identification value for the type of target TG. The type can be, for example, a pedestrian or a vehicle. The type of target TG is determined, for example, from the target TG's movement speed and direction of movement (value of θ). For example, a target TG whose speed along the X-axis is greater than a predetermined speed is determined to be a vehicle, and a target TG whose speed along the X-axis is approximately zero and whose speed along the Y-axis is within a predetermined range is determined to be a pedestrian. For example, an identification value of "1" for the type indicates that the target TG is a pedestrian, an identification value of "2" indicates that the target TG is a vehicle, and an identification value of "3" indicates that the target TG is something else, that is, the target TG is neither a pedestrian nor a vehicle.

[0113] The "inside / outside flag" contains an identification value indicating whether the target TG is located inside or outside the pedestrian crossing 20. An identification value of "1" for the inside / outside flag indicates that the target TG is located inside the pedestrian crossing 20, and an identification value of "0" indicates that the target TG is located outside the pedestrian crossing 20. For example, by determining whether the planar position of the target TG is located inside the zebra area 31, it can be determined whether the target TG is located inside the pedestrian crossing 20.

[0114] The "Stop Flag" contains an identification value that indicates whether the target TG is stopped or moving. An identification value of "1" for the Stop Flag indicates that the target TG is stopped, and an identification value of "0" indicates that the target TG is moving.

[0115] The "Reliability" field displays the value of the reliability data RD. The reliability data RD indicates whether or not the target TG is trusted as a pedestrian at crosswalk 20. A reliability identifier of "1" indicates "reliable," and a reliability identifier of "0" indicates "unreliable." If "reliable," the reliability of the pedestrian determination is high, meaning there is a high probability that the target TG is a pedestrian crossing. If "unreliable," the reliability of the pedestrian determination is low, meaning there is a low probability that the target TG is a pedestrian crossing.

[0116] The "Estimated Arrival Time" indicates the estimated time from the measurement time until the target TG has crossed pedestrian crossing 20.

[0117] The embodiments disclosed herein are illustrative in all respects and are not restrictive. The scope of the present invention is indicated by the claims rather than by the embodiments described above, and includes the meaning of equivalents of the claims and all modifications within that scope.

[0118] Each process (each function) of the above-described embodiment may be executed by a processing circuit (Circuitry) including one or more processors. The processing circuit may consist of an integrated circuit that combines one or more processors, one or more memories, various analog circuits, and various digital circuits. One or more memories store programs (instructions) that cause one or more processors to execute each process. One or more processors may execute each process according to the programs read from one or more memories. They may also execute each process according to logic circuits that have been pre-designed to execute each process. One or more processors may be various processors suitable for computer control, such as a CPU, GPU, DSP (Digital Signal Processor), FPGA (Field Programmable Gate Array), ASIC (Application Specific Integrated Circuit), etc. Multiple physically separated processors may cooperate with each other to perform their respective tasks. For example, processors installed in multiple physically separated computers may cooperate with each other to perform their respective tasks via a network such as a LAN (Local Area Network), WAN (Wide Area Network), or the Internet.

[0119] [Other Modifications] In the above embodiment, the display format for representing the accuracy of the target TG is a display format that switches the brightness of the dot icon, that is, a display format that switches between a black dot icon and a white dot icon. The display format for representing the accuracy of the target TG may be any other display format, as long as the user can identify the accuracy. Other display formats include, for example, a display format that switches the saturation of the dot icon, a display format that switches between the dot icon being lit and blinking, and a display format that switches the shape of the dot icon.

[0120] In the embodiment described above, the radio wave sensor 10 may consist of two physically separated devices. For example, the radio wave sensor 10 may consist of a housing including a transmitting / receiving unit 104 and a housing including a processor 101 and a communication interface 107, and these two housings may be separated.

[0121] In the above-described embodiment, the processor 101 of the radio wave sensor 10 may determine the accuracy (reliability) based on the crossing time CT of the target TG. That is, the processor 101 may determine the accuracy by determining whether or not the inequality "CT ≥ ThT" holds. For example, the processor 101 may determine the accuracy based only on the comparison result of the crossing time CT and the time threshold ThT. In this case, if the inequality "CT ≥ ThT" holds, the processor 101 determines the value of the reliability data RD to "1", and if the inequality "CT ≥ ThT" does not hold, the processor 101 determines the value of the reliability data RD to "0". This reduces the possibility of missing a pedestrian crossing.

[0122] 1 Vehicle signal light 2 Pedestrian signal light 10 Radio wave sensor 20 Crosswalk 30 Detection area 31 Zebra area 32a, 32b Standby area 40 Radio wave irradiation area 50 Structure 51 Pole 52 Arm 63a, 63b Sidewalk 60, 65 Roadway 61a, 61b Inbound lane 62a, 62b Outbound lane 61c, 62c Corner cut 70 Intersection 101 Processor 102 Non-volatile memory 103 Volatile memory 104 Transmitting / receiving unit 105 Transmitting circuit 106 Receiving circuit 105a Transmitting antenna 106a Receiving antenna 107 Communication interface (communication I / F) 110 Control program 111 Outline data 112 Outline data 200 Management terminal (terminal device) 201 Processor 202 Non-volatile memory 203 Volatile memory 204 Input / Output Interface (Input / Output I / F) 205 Graphics controller 206 Communication Interface (Communication I / F) 210 Control program 211 Input device 212 Display device 300 Signal controller 301 Control unit 302 Memory unit 303 Communication Interface (Communication I / F) 304 Light drive unit 305 Control program P Origin of the plane coordinate system TG Target (or its icon) AR Crossing area (or its icon) VS Vector representing the direction of movement of TG VY Vector representing the Y-axis direction TLV1 Field where static data is stored TLV2 Field where target data is stored

Claims

1. A radio wave sensor that senses using radio waves, comprising: a transmitting and receiving unit that transmits and receives radio waves; and a processor that generates a detection result including the position and speed of a target based on the transmitted and received radio waves, and outputs a communication frame including a storage field for the detection result, wherein the storage field includes a field for storing confidence data representing the degree of certainty that the target is a pedestrian crossing a crosswalk.

2. The radio wave sensor according to claim 1, wherein the processor determines the accuracy based on the transverse distance of the target.

3. The radio wave sensor according to claim 1, wherein the processor determines the accuracy based on the crossing distance and crossing time of the target.

4. The radio wave sensor according to any one of claims 1 to 3, wherein the processor determines the accuracy based on the direction of movement of the target.

5. A management terminal that is communicatively connected to a radio wave sensor according to any one of claims 1 to 4, comprising: a communication interface for receiving the communication frame; a display device for displaying icons representing the crossing area and the target on a screen; and a graphics controller for causing the display device to output the icons based on the detection results included in the communication frame, wherein the graphics controller determines the display format of the icons based on the reliability data.

6. The management terminal according to claim 5, further comprising a processor capable of setting the reliability data generation logic to be executed by the radio wave sensor by communicating with the radio wave sensor.

7. A detection method performed by a radio wave sensor according to any one of claims 1 to 4, comprising the steps of: generating a detection result based on transmitted radio waves and received radio waves; and outputting a communication frame.

8. A computer program that causes a computer to function as the processor of the radio wave sensor described in any one of claims 1 to 4.

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