WO2020100401A1

WO2020100401A1 - Radio wave sensor and safe-driving assistance system

Info

Publication number: WO2020100401A1
Application number: PCT/JP2019/035903
Authority: WO
Inventors: 東田宣男; 白永英晃
Original assignee: 住友電気工業株式会社
Priority date: 2018-11-12
Filing date: 2019-09-12
Publication date: 2020-05-22

Abstract

This radio wave sensor comprises a transmission unit for transmitting radio waves, a reception unit for receiving radio waves, a sensing unit for performing sensing processing for sensing an object on the basis of received radio waves which are radio waves received by the reception unit, a determination unit for making a determination relating to the periodicity of the received radio waves, and an adjustment unit for adjusting the timing of radio wave transmission by the transmission unit on the basis of the result of determination by the determination unit.

Description

Radio wave sensor and safe driving support system

The present invention relates to a radio wave sensor and a safe driving support system.
This application claims the priority on the basis of Japanese application Japanese Patent Application No. 2018-211984 for which it applied on November 12, 2018, and takes in those the indications of all here.

Japanese Patent Laying-Open No. 2018-004508 (Patent Document 1) discloses the following technique. That is, the radio wave sensor includes a transmitter that repeatedly transmits a radio wave having a predetermined pattern, a receiver that receives the radio wave, a frequency component of the radio wave transmitted by the transmitter, and a frequency component of the radio wave received by the receiver. And a pattern signal acquisition unit that generates a difference signal for each pattern having a frequency component of a difference between and, and an addition unit that adds the difference signals at the corresponding timings in a plurality of patterns with respect to a plurality of timings in the pattern. And a detection unit that detects an object based on the difference signals at the plurality of timings that are respectively added by the addition unit.

JP, 2008-004508, A JP, 2011-199689, A

(1) A radio wave sensor according to the present disclosure includes a transmitting unit that transmits a radio wave, a receiving unit that receives a radio wave including a reflected wave of the radio wave transmitted by the transmitting unit, and a radio wave received by the receiving unit. A detection unit that performs detection processing for detecting an object based on radio waves, a determination unit that determines the periodicity of the received radio waves, and a transmission timing of radio waves by the transmission unit based on the determination result of the determination unit. And an adjusting unit for adjusting.

(6) The safe driving support system of the present disclosure includes a radio wave sensor, a signal control device that creates and transmits information related to safe driving support based on a detection result of the radio wave sensor, and the signal control device that receives the signal control device. A radio transmitter for transmitting radio waves containing information, wherein the radio wave sensor includes a transmitter for transmitting radio waves, a receiver for receiving radio waves including reflected waves of the radio waves transmitted by the transmitter, and the receiver Based on the received radio wave that is a radio wave received by the unit, a detection unit that performs a detection process to detect an object, a determination unit that determines the periodicity of the received radio wave, and based on the determination result of the determination unit And an adjusting unit that adjusts the transmission timing of the radio wave by the transmitting unit.

One aspect of the present disclosure may be realized not only as a radio wave sensor including such a characteristic processing unit but also as a method having such characteristic processing as a step, or causing a computer to execute the step. Can be realized as a program for. Further, one embodiment of the present disclosure can be realized as a semiconductor integrated circuit which realizes part or all of a radio wave sensor.

FIG. 1 is a diagram showing a configuration of a safe driving support system according to an embodiment of the present invention. FIG. 2 is a diagram showing a state in which an installation example at the intersection of the safe driving support system according to the exemplary embodiment of the present invention is viewed obliquely from above. FIG. 3 is a diagram showing the configuration of the radio wave sensor in the safe driving support system according to the embodiment of the present invention. FIG. 4 is a diagram showing an example of the detection period and each sequence set by the control unit in the radio wave sensor according to the embodiment of the present invention. FIG. 5 is a diagram showing an example of respective waveforms of the trigger signal and the divided clock signal generated by the control unit and the clock generation circuit in the radio wave sensor according to the embodiment of the present invention. FIG. 6 is a diagram showing an example of respective waveforms of a transmission wave and a difference signal generated by the transmission unit and the difference signal generation unit in the radio wave sensor according to the embodiment of the present invention. FIG. 7 is a diagram showing a configuration of a signal processing unit in the radio wave sensor according to the embodiment of the present invention. FIG. 8 is a diagram showing an example of a processing spectrum generated by the FMCW processing unit in the radio wave sensor according to the embodiment of the present invention. FIG. 9 is a diagram showing an example of respective waveforms of a reception radio wave and a differential signal received by the receiving unit in the radio wave sensor according to the embodiment of the present invention. FIG. 10 is a diagram showing an example of the waveform of the differential signal stored in the memory of the radio wave sensor according to the embodiment of the present invention. FIG. 11 is a diagram showing an example of correlation values calculated in the radio wave sensor according to the embodiment of the present invention. FIG. 12 is a diagram showing another example of each waveform of the received radio wave and the differential signal in the radio wave sensor according to the embodiment of the present invention. FIG. 13 is a diagram showing another example of the correlation value calculated in the radio wave sensor according to the embodiment of the present invention. FIG. 14 is a diagram showing an example of each waveform of a received radio wave and a differential signal in the radio wave sensor according to the embodiment of the present invention. FIG. 15 is a diagram showing an example of a period that can be changed as a new transmission timing in the radio wave sensor according to the embodiment of the present invention. FIG. 16 is a diagram showing an example of how the radio wave transmission timing is changed in the radio wave sensor according to the embodiment of the present invention. FIG. 17 is a diagram showing an example of the target reflected wave and the interference wave after the transmission timing of the radio wave is changed in the radio wave sensor according to the embodiment of the present invention. FIG. 18 is a diagram showing an example of each waveform of a received radio wave and a differential signal in the radio wave sensor according to the embodiment of the present invention. FIG. 19 is a flowchart that defines an operation procedure when the radio wave sensor according to the embodiment of the present invention determines the periodicity of the received radio wave and adjusts the transmission timing of its own radio wave. FIG. 20 is a flowchart that defines an operation procedure when the determination unit in the radio wave sensor according to the embodiment of the present invention makes a determination regarding the periodicity of received radio waves.

[Problems to be solved by the present disclosure]
Beyond the technique described in Patent Document 1, there is a demand for a technique capable of avoiding radio wave interference and detecting a target object better.

The present disclosure has been made to solve the above problems, and an object thereof is to provide a radio wave sensor and a safe driving support system capable of avoiding radio wave interference and detecting a target object better. That is.

[Effect of the present disclosure]
According to the present disclosure, it is possible to avoid radio wave interference and detect a target object better.

[Description of Embodiments of the Present Invention]
First, the contents of the embodiments of the present invention will be listed and described.

(1) A radio wave sensor according to an embodiment of the present invention includes a transmitter that transmits radio waves, a receiver that receives radio waves including reflected waves of the radio waves transmitted by the transmitter, and a receiver that receives the radio waves. Based on a received radio wave that is a received radio wave, a detection unit that performs detection processing for detecting an object, a determination unit that determines the periodicity of the received radio wave, and the transmission unit based on the determination result of the determination unit. And an adjusting unit that adjusts the transmission timing of the radio wave.

In this way, with the configuration that determines the periodicity of received radio waves, when there is another device that transmits radio waves, the device that is the source of the received radio waves is fixed Since it is possible to judge whether or not the device is installed in the same place, more accurate transmission timing control is performed without being affected by the temporary radio waves from unfixed devices such as in-vehicle devices. be able to. Therefore, it is possible to avoid the interference of radio waves and detect the object better. Further, the periodicity of the received radio wave can be determined without demodulating the signal included in the received radio wave.

(2) Preferably, the transmission unit intermittently transmits radio waves, and the determination unit determines the periodicity of the received radio waves during the non-transmission period of radio waves by the transmission unit.

With such a configuration, it is possible to easily detect radio waves from other devices during the non-transmission period while performing the normal operation of detecting an object. Further, it is possible to easily obtain the correct change destination of the transmission timing.

(3) Preferably, the radio wave sensor further includes a setting unit that sets a detection period in which the detection process is performed and a non-detection period in which the detection unit is not performed and radio waves are not transmitted from the transmission unit, and the determination is performed. The unit determines the periodicity of the received radio wave in the non-detection period.

As described above, by providing the non-detection period, it is difficult to detect a radio wave from another device that is difficult to detect during the detection period, for example, the radio wave from another device that receives the radio wave when its own transmitted radio wave is reflected by the object. , Can be easily detected.

(4) Preferably, the determination unit calculates a correlation between the radio wave transmitted by the transmission unit and the received radio wave, and makes a determination regarding the periodicity based on the calculated correlation.

With this configuration, it is possible to easily determine the periodicity based on the waveform of the received radio wave.

(5) Preferably, the determination unit determines the periodicity based on whether or not the received radio wave satisfies a predetermined condition regarding another device that transmits a radio wave that becomes an interference wave with respect to the radio wave transmitted by the transmission unit. Make decisions about.

In this way, for example, the radio wave sensor may have periodicity based on characteristics other than the waveform of the received radio wave, such as the transmission timing of the radio wave of another device that transmits an electric wave that becomes an interference wave of the received radio wave and the distance to the device. With the configuration for determining, the periodicity of the received radio wave can be determined by using the measurement result of the received radio wave that is received less frequently. Thereby, the periodicity of the received radio wave can be determined in a shorter time.

(6) A safe driving assistance system according to an embodiment of the present invention includes a radio wave sensor, a signal control device that creates and transmits information regarding safe driving assistance based on a detection result of the radio wave sensor, and the signal control. A radio transmission device for transmitting a radio wave containing the information received from the device, wherein the radio wave sensor receives a radio wave including a transmission part for transmitting the radio wave and a reflected wave of the radio wave transmitted by the transmission part. Section, a detection section that performs detection processing for detecting an object based on a received radio wave that is a radio wave received by the reception section, a determination section that determines the periodicity of the received radio wave, and a determination section of the determination section. An adjusting unit that adjusts the transmission timing of the radio wave by the transmitting unit based on the determination result.

Embodiments of the present invention will be described below with reference to the drawings. It should be noted that the same or corresponding parts in the drawings are designated by the same reference numerals and the description thereof will not be repeated. Further, at least a part of the embodiments described below may be arbitrarily combined.

[Configuration and basic operation]
FIG. 1 is a diagram showing a configuration of a safe driving support system according to an embodiment of the present invention. FIG. 2 is a diagram showing a state in which an installation example at the intersection of the safe driving support system according to the exemplary embodiment of the present invention is viewed obliquely from above.

1 and 2, the safe driving support system 301 includes a radio wave sensor 101, a relay device 141, a signal control device 151, a wireless transmission device 152, an antenna 153, and a pedestrian signal light device 161. Equipped with. The signal control device 151 and the pedestrian signal light device 161 in the safe driving support system 301 constitute a traffic signal and are installed, for example, near the intersection CS1.

[About the intersection]
For example, as shown in FIG. 2, a pedestrian crossing PC1 is provided near the intersection CS1. Here, the road provided with the pedestrian crossing PC1 is defined as the target road Rd1. The target road Rd1 forms an intersection CS1. Further, a road that intersects with the target road Rd1 at the intersection CS1 is defined as an intersection road Rd2.

That is, the intersection of the target road Rd1 and the intersection road Rd2 is the intersection CS1. In other words, the intersection CS1 overlaps with the target road Rd1 and also overlaps with the intersection road Rd2. At the intersection CS1, more roads may intersect.

The target road Rd1 includes an outflow road Rde, which is driven by an unillustrated automobile Tgt1 flowing out of the intersection CS1, and an inflow road Rdi, which is driven by the automobile Tgt1 flowing into the intersection CS1. A lane TrL is provided between the outflow road Rde and the inflow road Rdi.

A sidewalk Pv1 is provided at the opposite end of the inflow road Rdi with respect to the outflow road Rde so as to extend along the target road Rd1. The sidewalk Pv1 changes its extension direction from the direction along the target road Rd1 to the direction along the intersection road Rd2 by extending along the arcuate corner cut CCe in the vicinity of the intersection CS1.

A sidewalk Pv2 is provided at the opposite end of the outflow road Rde to the inflow road Rdi so as to extend along the target road Rd1. The sidewalk Pv2 extends along the arcuate corner cut CCi near the intersection CS1 to change the extension direction from the direction along the target road Rd1 to the direction along the intersection road Rd2.

The target area A1 is at least a part of the irradiation range of the radio wave transmitted from the radio wave sensor 101, and is an area including, for example, all of the pedestrian crossing PC1.

The radio wave sensor 101 can detect an object in the target area A1. More specifically, the radio wave sensor 101 detects a pedestrian Tgt2 crossing the road using the pedestrian crossing PC1 as the target Tgt in the target area A1. Here, the pedestrian Tgt2 is not limited to a walking person, and includes a bicycle and the like. In addition to the pedestrian Tgt2, the target Tgt may include an automobile Tgt1 that runs along the target road Rd1 and passes through the pedestrian crossing PC1.

[Radio sensor installation position]
The radio wave sensor 101 is installed, for example, near the target road Rd1. Specifically, the radio wave sensor 101 is fixed to a pillar PW installed on the side opposite to the target road Rd1 with respect to the sidewalk Pv1. More specifically, the radio wave sensor 101 is provided on an extension of the pedestrian crossing PC1 toward the sidewalk Pv1.

The relay device 141 is fixed to the support PW. Although not shown in FIG. 2, the radio wave sensor 101 and the relay device 141 are connected by, for example, a signal line. The relay device 141 performs a relay process of transmitting the information received from the radio wave sensor 101 to the signal control device 151. The safe driving support system 301 may not have the relay device 141 and may be configured such that the radio wave sensor 101 and the signal control device 151 are directly connected by a signal line or the like.

The signal control device 151 and the wireless transmission device 152 are fixed to a pillar PV installed on the sidewalk Pv2. The antenna 153 is fixed to the top of the pillar PV.

The two pedestrian signal lights 161 are fixed to the columns PW and PV, respectively. Although not shown in FIG. 2, the signal control device 151, the wireless transmission device 152, the relay device 141, and the two pedestrian signal light devices 161 are connected by signal lines. Although not shown in FIG. 2, the wireless transmission device 152 and the antenna 153 are connected by a signal line.

The radio wave sensor 101 transmits a radio wave to the target area A1. Objects located in the target area A1, such as the automobile Tgt1, the pedestrian Tgt2, and the pillar PV, reflect the radio waves transmitted from the radio wave sensor 101. The radio wave sensor 101 receives a radio wave reflected by an object.

The radio wave sensor 101 detects the pedestrian Tgt2 on the pedestrian crossing PC1 based on the received radio wave, and transmits the detection result to the signal control device 151 via the relay device 141.

According to the control of the signal control device 151, the pedestrian signal light device 161 lights up and displays “recommendation” or “remarkable” for the pedestrian Tgt2 crossing the pedestrian crossing PC1.

For example, the signal control device 151 extends the remaining time when the detection result indicates that the pedestrian Tgt2 is detected at the pedestrian crossing PC1 in the case where the remaining time for turning on “Recommendation” in the pedestrian signal light device 161 is small. I do. Note that the signal control device 151 may notify the pedestrian Tgt2 by voice that the remaining time for lighting “Recommendation” is short.

Further, when the signal control device 151 lights “Tomare” in the pedestrian signal light device 161, when the detection result indicates that the pedestrian Tgt2 is detected at the pedestrian crossing PC1, the signal control device 151 walks to the effect that it is dangerous. The person Tgt2 is warned by voice.

The signal control device 151 creates information regarding safe driving support based on the detection result received from the radio wave sensor 101, and transmits the information to the wireless transmission device 152.

The wireless transmission device 152 transmits a radio wave including the information received from the signal control device 151.

As an example, the signal control device 151 provides a service to the automobile Tgt1 based on the detection result received from the radio wave sensor 101.

Specifically, when the detection result indicates that the pedestrian Tgt2 exists at the pedestrian crossing PC1, the signal control device 151 creates pedestrian warning information indicating that the pedestrian Tgt2 at the pedestrian crossing PC1 should be noted. , And transmits the created pedestrian warning information to the wireless transmission device 152.

When the wireless transmission device 152 receives the pedestrian warning information from the signal control device 151, the wireless transmission device 152 generates a radio wave including the received pedestrian warning information, and transmits the generated radio wave via the antenna 153. The pedestrian warning information is notified to the automobile Tgt1.

For example, when the vehicle Tgt1 (not shown) turning right or left from the intersection road Rd2 and trying to pass the pedestrian crossing PC1 receives the radio wave transmitted from the wireless transmission device 152, it acquires the pedestrian warning information included in the received radio wave. Then, based on the acquired pedestrian warning information, the driver of the automobile Tgt1 is notified that the crossing target on the pedestrian crossing PC1 should be noted.

[Task]
For example, when a plurality of radio wave sensors are installed in a short distance and the radio wave sensors transmit radio waves at the same timing, radio wave interference may occur and the detection accuracy may deteriorate.

As an example of a technique for avoiding radio wave interference, Japanese Patent Laying-Open No. 2011-199689 (Patent Document 2) discloses that a transmitting side transmits its own transmission timing and the like to a receiving side as follows. A wireless communication system for synchronizing a receiving side and a receiving side is disclosed.

That is, the wireless communication system is a wireless communication system including a transmitter and a receiver, and the transmitter modulates a carrier wave by the PDU generation unit that generates a PDU with a time stamp. A modulation transmitting unit that transmits a radio wave from a transmitting antenna, and a transmission delay time of the following "transmission delay time from the time of setting the time stamp to the time of transmitting the radio wave" is added to its own local time to obtain the time stamp. A time correction unit, and the receiver includes a demodulation reception unit that extracts the PDU from a radio signal that reaches a reception antenna, an SDU reproduction unit that reproduces the SDU and the time stamp from the PDU, The following "Reception delay time from reception of radio wave to arrival of preamble to SDU playback unit" and "Reception delay time from arrival of preamble to SDU playback unit to acquisition of time stamp" And a second time correction unit for adding the reproduction delay time to the time stamp to obtain a correction time value.

However, radio wave sensors such as radar sensors that use millimeter waves often do not have the function of demodulating signals based on received radio waves. Therefore, the method described in Patent Document 2 is difficult to realize, for example, in a radar sensor using a millimeter wave.

On the other hand, the radio wave sensor according to the embodiment of the present invention solves the above problem by the following configuration and operation.

[Radio sensor configuration]
FIG. 3 is a diagram showing the configuration of the radio wave sensor in the safe driving support system according to the embodiment of the present invention.

Referring to FIG. 3, a radio wave sensor 101 includes a transmitter 1, a receiver 2, a difference signal generator 3, a controller (adjustment unit and setting unit) 4, a signal processor 5, and a clock generator. 6 and a detection processing unit (detection unit) 7. The radio wave sensor 101 does not have a function of modulating / demodulating radio waves.

The transmitting unit 1 includes a transmitting antenna 21, a power amplifier 22, a directional coupler 23, a VCO (Voltage-Controlled Oscillator) 24, a voltage generating unit 25, and a switch 26. The reception unit 2 includes a reception antenna 31 and a low noise amplifier 32.

The differential signal generator 3 includes a mixer 33, an IF (Intermediate Frequency) amplifier 34, a low-pass filter 35, and an A / D converter (ADC) 36.

The radio wave sensor 101 is, for example, Non-Patent Document 1 (Koji Yoichi, 2 persons, “Expanding application of millimeter wave technology”, [online], [search on May 22, 2016], Internet <URL: http: //Www.spc.co.jp/spc/pdf/giho21_09.pdf>) and Non-Patent Document 2 (Takayuki Inaba, Tetsuro Kirimoto, "In-vehicle millimeter-wave radar", Automotive Technology, February 2010, 64th) Vol. 2, No. 2, p. 74-79), which is a radar for detecting an object Tgt using the FM-CW method.

FIG. 4 is a diagram showing an example of the detection period and each sequence set by the control unit in the radio wave sensor according to the embodiment of the present invention. In addition, in FIG. 4, the horizontal axis represents time.

The detection processing unit 7 performs a detection process of detecting an object based on the received radio wave that is the radio wave received by the reception unit 2.

Specifically, with reference to FIG. 4, the control unit 4 in the radio wave sensor 101 sets a detection period in which the radio wave sensor 101 of its own outputs the detection result of the target Tgt once, for example.

More specifically, the control unit 4 sets the detection period having the length Pm, for example, based on the moving speed of the object Tgt. The length Pm is variable, for example. Details of the setting method of the detection period length Pm will be described later.

The detection period includes, for example, M sequences of Seq1 to SeqM. Here, M is an integer of 2 or more. In one sequence, one pattern of radio waves or one sub-pattern of radio waves is transmitted from the transmission unit 1.

FIG. 5 is a diagram showing an example of each waveform of a trigger signal and a divided clock signal generated by the control unit and the clock generation circuit in the radio wave sensor according to the embodiment of the present invention. In FIG. 5, the horizontal axis represents time and the vertical axis represents the level of each signal.

The clock generation circuit 6 generates, for example, a clock signal and a divided clock signal. Specifically, the clock generation circuit 6 generates, for example, a rectangular wave clock signal CLK having a cycle Tck. Further, the clock generation circuit 6 generates the divided clock signal CS having the cycle Tc by dividing the generated clock signal CLK by, for example, 10.

Then, the clock generation circuit 6 outputs the generated clock signal CLK to the differential signal generation unit 3, and outputs the generated divided clock signal CS to the control unit 4 and the differential signal generation unit 3.

The control unit 4 sets each sequence. More specifically, the control unit 4 generates the trigger signal TS at each start timing of each sequence, and outputs the generated trigger signal TS to the transmission unit 1 and the signal processing unit 5.

Specifically, for example, the control unit 4 counts the number of rising edges of the divided clock signal CS received from the clock generation circuit 6 and generates and outputs the trigger signal TS every Ns of the edges. .. Here, Ns is an integer of 2 or more, and may be a predetermined value or may be variable. A value obtained by multiplying the cycle Tc by Ns is the cycle Tt of one sequence. In this example, the value of Ns is set so that the cycle Tt is, for example, 0.1 ms to 100 ms.

FIG. 6 is a diagram showing an example of respective waveforms of a transmission wave and a difference signal generated by the transmission unit and the difference signal generation unit in the radio wave sensor according to the embodiment of the present invention. In FIG. 6, the horizontal axis represents time, and the vertical axis represents the frequencies Ft and Fr of the transmitted and received radio waves, the frequency Fb of the differential signal, and the amplitude Ab of the differential signal in order from the top of the paper. The frequency Ft of the transmitted radio wave is represented by the solid line, and the frequency Fr of the received radio wave is represented by the broken line. In FIG. 6, the delay of the received radio wave with respect to the transmitted radio wave is shown.

With reference to FIGS. 3 and 6, the transmission unit 1 intermittently transmits radio waves of a predetermined pattern. Specifically, the transmission unit 1 repeatedly transmits, for example, a radio wave generated using the FM-CW modulation method to the target area A1. More specifically, for example, as shown in FIG. 6, the transmission unit 1 repeatedly transmits a radio wave of a pattern Pt1 in which the frequency Ft increases by a predetermined amount per unit time to the target area A1. The transmitting unit 1 is not limited to the configuration that periodically transmits radio waves, but may have a configuration that irregularly transmits radio waves.

Note that the transmitter 1 may transmit radio waves in a pattern in which the frequency Ft decreases by a predetermined amount per unit time. The pattern of the radio wave transmitted by the transmitter 1 is not limited to the configuration determined by the time change of the frequency as shown in FIG. 6, but may be the configuration determined by the time change of the amplitude.

The control unit 4 outputs the transmission parameters used in the FM-CW method to the transmission unit 1, the signal processing unit 5, and the detection processing unit 7, for example, for each detection period. Here, the transmission parameters include the sweep start frequency F2, the frequency sweep direction, the frequency sweep width Δf, the period Tt which is the length of one sequence, the sweep time Ts, the period Tc of the divided clock signal CS, and the length of the detection period. Pm is included.

Further, the control unit 4 generates the guard signal GS indicating the start timing of the guard period Gp in which the radio wave is not transmitted from the transmission unit 1 at the timing when the sweep time Ts has elapsed after the generation of the trigger signal TS, and transmits the guard signal GS to the transmission unit 1. Output.

The guard signal GS is synchronized with the divided clock signal CS. The guard period Gp is provided, for example, at the rear of each sequence, and continues after the guard signal GS is output until the trigger signal TS indicating the start timing of the next sequence is output. The guard period Gp may be provided in the front part of each sequence.

Upon receiving the trigger signal TS from the control unit 4, the voltage generation unit 25 in the transmission unit 1 uses the sweep start frequency F2, the frequency sweep direction, the frequency sweep width Δf, and the sweep time Ts received from the control unit 4 in advance as transmission parameters. Then, in the transmission period Tp, a voltage whose magnitude increases at a constant rate (hereinafter, also referred to as FM modulation voltage) is generated and output to the VCO 24.

The transmission period Tp is a period during which a radio wave is transmitted from the transmission unit 1. Specifically, the sweep time Ts elapses after the voltage generation unit 25 receives the trigger signal TS from the control unit 4, and the guard signal GS is transmitted. It is the period until receiving.

The VCO 24 generates a transmission wave RFt having a frequency according to the magnitude of the voltage received from the voltage generator 25.

More specifically, the VCO 24 generates a transmission wave RFt in the 24 GHz band having a frequency sweep width of Δf and outputs it to the directional coupler 23 in accordance with the FM modulation voltage received from the voltage generator 25.

The directional coupler 23 distributes the transmission wave RFt received from the VCO 24 to the switch 26 and the differential signal generator 3.

The switch 26 has a first end connected to the directional coupler 23 and a second end connected to the power amplifier 22. When the switch 26 receives the trigger signal TS from the control unit 4, the switch 26 transitions to the ON state and electrically connects the first end and the second end. On the other hand, when the switch 26 receives the guard signal GS from the control unit 4, the switch 26 transitions to the off state and electrically insulates the first end and the second end. As a result, the transmission wave RFt output by the VCO 24 is not transmitted to the power amplifier 22 in the guard period Gp, but is transmitted to the power amplifier 22 in the transmission period Tp that is a period different from the guard period Gp.

The power amplifier 22 amplifies the transmission wave RFt received from the switch 26 and transmits the amplified transmission wave RFt to the target area A1 via the transmission antenna 21.

The receiving unit 2 receives an electric wave from the target area A1 or the like, that is, an electric wave including a reflected wave of the electric wave transmitted by the transmitting unit 1. More specifically, the receiving antenna 31 in the receiving unit 2 stops the target object Tgt in the target area A1, specifically, a movable object such as a pedestrian Tgt2 and an automobile Tgt1, and a guardrail and a pillar PV. It is possible to receive the radio waves reflected by an object that is present. Hereinafter, the operation of the radio wave sensor 101, which is suitable when the target Tgt is a movable object, will be described.

Also, the receiving antenna 31 may receive a radio wave transmitted by an interfering object that transmits an interference wave. The interfering object is, for example, an electronic scanning type millimeter-wave radar device mounted on the automobile Tgt1 located in the target area A1 or outside the target area A1.

The low noise amplifier 32 amplifies the received radio wave, which is the radio wave received by the reception antenna 31, and outputs the amplified radio wave to the difference signal generation unit 3.

The difference signal generation unit 3 generates a difference signal having a frequency component that is the difference between the frequency component of the radio wave transmitted by the transmission unit 1 and the frequency component of the radio wave received by the reception unit 2.

More specifically, the mixer 33 in the difference signal generation unit 3 generates an analog difference signal Ba1 having a frequency component of the difference between the transmission wave RFt received from the transmission unit 1 and the reception radio wave received from the low noise amplifier 32.

The time change of the frequency Fb and the amplitude Ab of the differential signal Ba1 is shown in FIG. The mixer 33 outputs the generated difference signal Ba1 to the IF amplifier 34.

The IF amplifier 34 amplifies the differential signal Ba1 received from the mixer 33 and outputs it to the low-pass filter 35.

The low-pass filter 35 attenuates a frequency component of a predetermined frequency or higher among the frequency components of the differential signal Ba1 amplified by the IF amplifier 34.

The A / D converter 36 performs sampling processing of the differential signal Ba1 at the cycle Tck of the clock signal CLK, for example. More specifically, the A / D converter 36 sets the difference signal Ba1 that has passed through the low-pass filter 35 by q bits (q is 2 or more) every sampling cycle Tck in accordance with the timing of the rising edge of the clock signal CLK received from the clock generation circuit 6. To the digital difference signal Bd1.

In FIG. 6, among the sampling timings in the sequences Seq1 and Seq2, the sampling timings for each cycle Tc of the divided clock signal CS are indicated by white circles. Sampling numbers 1 to 12 indicating the sampling order are assigned to the sampling timing for each cycle Tc in each sequence. The A / D converter 36 outputs the converted differential signal Bd1 to the signal processing unit 5.

FIG. 7 is a diagram showing a configuration of a signal processing unit in the radio wave sensor according to the embodiment of the present invention.

With reference to FIG. 7, the signal processing unit 5 includes a memory 41, an FFT (Fast Fourier Transform) processing unit 42, an FMCW processing unit 43, a pattern signal acquisition unit 44, an addition unit 45, and a determination unit 46. including.

The memory 41 in the signal processing unit 5 stores the differential signal Bd1 received from the A / D converter 36.

The pattern signal acquisition unit 44 generates a set of difference signals Bd1 for each cycle Tc (hereinafter, also referred to as pattern signal) corresponding to the pattern Pt1 based on the cycle Tc received from the control unit 4. More specifically, the pattern signal acquisition unit 44 recognizes the start timing and the end timing of one sequence based on the trigger signal TS received from the control unit 4.

Then, the pattern signal acquisition unit 44 stores the difference signal Bd1 for each cycle Tc, that is, the pattern signal, among the time-series difference signals Bd1 sampled at the sampling cycle Tck in the sequence, for example, every time a sequence ends. Take out from 41. The pattern signal acquisition unit 44 outputs the extracted pattern signal to the addition unit 45.

The adding unit 45 adds the difference signals at the corresponding timings in the plurality of patterns Pt1 with respect to the plurality of timings in the pattern Pt1. Specifically, the addition unit 45 adds the differential signals having the same sampling number in the plurality of patterns Pt1 at each sampling timing indicated by the sampling numbers 1 to 12 in the pattern Pt1.

More specifically, the adding unit 45 determines the number M of a plurality of patterns to be added, for example, for each detection period.

For example, the addition unit 45 determines the number M based on the detection period length Pm and the cycle Tt included in the transmission parameter received from the control unit 4.

Specifically, the addition unit 45 determines the value obtained by dividing the length Pm of the detection period by the cycle Tt as the number M.

The addition unit 45 repeatedly receives the pattern signal from the pattern signal acquisition unit 44. Specifically, for example, when the addition unit 45 receives the pattern signal from the pattern signal acquisition unit 44 at the timing when the sequence Seq1 shown in FIG. 6 has expired, the addition unit 45 accumulates the received pattern signal as the target pattern signal. The pattern signal includes the amplitude Ab sampled at each sampling timing indicated by the sampling numbers 1 to 12.

Then, when the pattern signal is received from the pattern signal acquisition unit 44 at the timing when the sequence Seq2 is completed, the addition unit 45 performs the following processing.

That is, the addition unit 45 updates the target pattern signal by adding the amplitudes Ab included in the target pattern signal and the amplitudes Ab included in the pattern signal of the sequence Seq2 between the amplitudes Ab having the same sampling number.

The adding unit 45 similarly updates the target pattern signal at the timing when each of the sequences Seq3 to SeqM expires. The addition unit 45 outputs the updated target pattern signal to the FFT processing unit 42.

When the FFT processing unit 42 receives the target pattern signal from the adding unit 45, the FFT processing unit 42 performs the FFT process on the received target pattern signal to generate the power spectrum FS1 and the phase spectrum PS1. Here, the power spectrum FS1 indicates the amplitude of each frequency component included in the difference signal Bd1 accumulated in the detection period. In addition, the phase spectrum PS1 indicates the phase of each frequency component included in the difference signal Bd1 accumulated in the detection period.

The FFT processing unit 42 outputs the generated power spectrum FS1 and phase spectrum PS1 to the FMCW processing unit 43.

FIG. 8 is a diagram showing an example of a processing spectrum generated by the FMCW processing unit in the radio wave sensor according to the embodiment of the present invention. In FIG. 8, the vertical axis represents intensity and the horizontal axis represents the distance from the radio wave sensor 101 to the object.

The FMCW processing unit 43 determines whether or not an object is present based on the radio wave received by the receiving unit 2.

Specifically, the FMCW processing unit 43 holds a background spectrum that is a power spectrum in a state where there are no movable objects such as a pedestrian Tgt2 and a car Tgt1 in the target area A1, for example.

Upon receiving the power spectrum FS1 and the phase spectrum PS1 from the FFT processing unit 42, the FMCW processing unit 43 generates a processed spectrum by subtracting each frequency component of the background spectrum from each frequency component of the received power spectrum FS1.

Further, the FMCW processing unit 43 converts the frequency Fb of the generated processing spectrum and the frequency Fb of the phase spectrum PS1 into the distance L.

More specifically, the relationship between the frequency Fb and the distance L is expressed by the following expression (1) based on the expression (1) in Non-Patent Document 1.

Where c is the speed of light. vr is a moving speed of the object along a direction approaching or moving away from the radio wave sensor 101 (hereinafter, also referred to as a detection target speed). f0 is an average of the sweep start frequency F2 and the sweep end frequency F1 obtained by adding the frequency sweep width Δf to the sweep start frequency F2.

For example, in the equation (1), when the frequency sweep width Δf is large with respect to the length of the period in which the radio wave is transmitted in one sequence, that is, the sweep time Ts, the distance L is approximated by the following equation (2). Can be expressed as

The FMCW processing unit 43 sets the frequency Fb on the horizontal axis of the processing spectrum and the phase spectrum PS1 to the distance L by using the frequency sweep width Δf and the sweep time Ts included in the transmission parameter received from the control unit 4 and the equation (2). Convert. FIG. 8 shows a processed spectrum in which the horizontal axis is converted from frequency to distance.

The FMCW processing unit 43 performs peak detection processing on the generated processing spectrum. More specifically, the FMCW processing unit 43 analyzes the processed spectrum and tries to detect a peak having an intensity equal to or higher than a predetermined threshold value Thfm.

The FMCW processing unit 43 determines that an object exists when a peak having an intensity equal to or higher than the threshold Thfm can be detected. In this example, the FMCW processing unit 43 detects one peak Pn1 and determines that an object exists. On the other hand, when the FMCW processing unit 43 cannot detect a peak having an intensity equal to or higher than the threshold Thfm, the FMCW processing unit 43 determines that there is no object.

The FMCW processing unit 43 outputs result information indicating the determination result, the intensity of the detected peak Pn1 and the distance L corresponding to the peak Pn1 to the detection processing unit 7.

Referring again to FIG. 3, the detection processing unit 7 detects the target Tgt based on the difference signals of the plurality of timings added by the adding unit 45.

Specifically, the detection processing unit 7 detects the target Tgt based on the result information received from the FMCW processing unit 43.

More specifically, the detection processing unit 7 determines that the target Tgt does not exist, for example, when the determination result indicated by the result information indicates the absence of the object.

On the other hand, for example, when the determination result indicated by the result information indicates the presence of an object, the detection processing unit 7 selects the pedestrian Tgt2 or the automobile Tgt1 as the type of the object Tgt based on the magnitude of the peak intensity indicated by the result information. Identify. Specifically, the detection processing unit 7 determines that the type of the target object Tgt is the automobile Tgt1 when the peak intensity is large, and determines the type of the target object is the pedestrian Tgt2 when the peak intensity is small.

Referring again to FIG. 7, the determination unit 46 determines the periodicity of received radio waves. For example, the determination unit 46 determines the periodicity of the radio wave received by the reception unit 2 during the non-transmission period of the radio wave by the transmission unit 1, that is, the guard period Gp.

FIG. 9 is a diagram showing an example of respective waveforms of a reception radio wave and a differential signal received by the receiving unit in the radio wave sensor according to the embodiment of the present invention. In FIG. 9, the horizontal axis represents time, and the vertical axis represents the frequencies Ft and Fr of the transmission radio wave and the reception radio wave and the frequency Fb of the differential signal in order from the upper side of the paper. The frequency Ft of the transmitted radio wave is represented by the solid line, and the frequency Fr of the received radio wave is represented by the broken line.

Further, in FIG. 9, among the sampling timings of each sequence, the digital difference signal Bd1 at the sampling timing for each cycle Tc of the divided clock signal CS is indicated by a white circle. The sampling timing for each cycle Tc in each sequence is represented by sampling numbers 1 to 12 indicating the sampling order.

FIG. 9 shows the frequencies Ft and Fr of the transmission radio wave and the reception radio wave when the reception radio wave includes a radio wave other than the target reflected wave, which is the radio wave in which the self transmission radio wave is reflected, in the guard period Gp in the radio wave sensor 101. And the frequency Fb of the difference signal.

For example, the determination unit 46 calculates the correlation between the radio wave transmitted by the transmission unit 1 and the received radio wave, and determines the periodicity of the radio wave included in the received radio wave based on the calculated correlation.

Specifically, the determination unit 46 detects the target reflected wave included in the radio wave received by the reception unit 2 based on the difference signal Bd1.

More specifically, the determination unit 46 determines, for example, the difference signal Bd1 for each cycle Tck in the period of the sampling numbers 12 to 5 including the difference signal Bd1 having the sampling numbers 1 to 4 corresponding to the sweep time Ts, It is acquired from the memory 41.

Then, the determination unit 46, for example, among the acquired difference signals Bd1, for each difference signal Bd1 corresponding to the sampling numbers 1 to 4, the difference signal Bd1 and ten difference signals before and after the difference signal Bd1. By performing FFT processing on Bd1, a spectrum FS0 corresponding to the differential signal Bd1 of the sampling number is generated. Then, the determination unit 46 obtains the value of the frequency component included in each corresponding difference signal Bd1 based on the generated spectrum FS0 for each sampling number.

Referring again to FIG. 6, the determination unit 46 determines that, for example, among the acquired difference signals Bd1, the value of the frequency component of the difference signal Bd1 having the sampling number 1 is zero, and the sampling numbers are 2 to 4. When the values of the frequency components of a certain difference signal Bd1 are all less than a predetermined positive threshold value F3, and the magnitudes thereof are the same, for example, the difference between the maximum value and the minimum value is less than the predetermined threshold value, each difference It is determined that the signal Bd1 is a differential signal based on the target reflected wave.

The determination unit 46 also determines whether the radio wave received by the reception unit 2 includes an interference wave that is a radio wave other than the target reflected wave, based on the difference signal Bd1.

In the guard period Gp, the value of the frequency component of the differential signal Bd1 indicates that the transmission wave from the transmission unit 1 is present when the radio wave received by the reception unit 2 includes an interference wave that is a radio wave other than the target reflected wave. Not doing so will result in a negative value. Therefore, the determination unit 46 confirms the sign of the differential signal Bd1 during the guard period Gp to determine whether the radio wave received by the reception unit 2 includes an interference wave that is a radio wave other than the target reflected wave. To judge.

More specifically, the determination unit 46 acquires, for example, a set of a plurality of continuous difference signals Bd1 corresponding to the guard period from the memory 41, and the difference signal Bd1 in the acquired set includes a difference signal Bd1 having a negative value. If the radio wave is received, it is determined that the radio wave received by the receiving unit 2 includes an interference wave. That is, the determination unit 46 detects the presence of a device that transmits a radio wave, other than its own radio wave sensor 101.

The determination unit 46 performs an interference wave detection process, for example, when it detects the presence of a device that transmits a radio wave other than its own radio wave sensor 101.

[Interference wave detection processing 1]
For example, when a radio wave sensor 101B, which is another radio wave sensor 101, is further installed on the pole PV shown in FIG. 2, the radio wave sensor 101A, which is the radio wave sensor 101 installed on the pole PW, transmits the radio wave transmitted from the radio wave sensor 101B. To receive.

For example, the administrator of the radio wave sensor 101A and the radio wave sensor 101B estimates the waveform of the differential signal Pd2 based on the received radio wave when the radio wave sensor 101A receives the transmission radio wave from the radio wave sensor 101B, and uses the estimated waveform. It can be registered in the memory 41 of the radio wave sensor 101A.

FIG. 10 is a diagram showing an example of the waveform of the differential signal stored in the memory of the radio wave sensor according to the embodiment of the present invention. In FIG. 10, the vertical axis represents the frequency Fb of the difference signal Pd2, and the horizontal axis represents time.

With reference to FIG. 10, in the memory 41 of the radio wave sensor 101A, for example, in accordance with the operation of the administrator, as the waveform of the difference signal Pd2, the difference analog-digital converted at four consecutive sampling timings at intervals of the cycle Tc. A set of signals Pd2 (hereinafter, also referred to as comparison waveform Wd2) is stored.

The determination unit 46 calculates the correlation between the comparison waveform Wd2 and the waveform of the difference signal Bd1, and determines whether the transmission timing of the interference wave is periodic based on the calculated correlation.

More specifically, the determination unit 46 acquires the comparison waveform Wd2 from the memory 41, for example. Further, the determination unit 46 acquires from the memory 41, for example, a set of difference signals Bd1 having sampling numbers 1 to 4 in a certain sequence.

Then, the determination unit 46 calculates the correlation between the acquired comparison waveform Wd2 and the pair of difference signals Bd1.

Next, the determination unit 46 acquires a set of difference signals Bd1 having sampling numbers 2 to 5 from the memory 41, and calculates a correlation between the acquired set of difference signals Bd1 and the comparison waveform Wd2.

Similarly, the determination unit 46 similarly acquires the set of difference signals Bd1 from the memory 41 while shifting the sampling number by 1, and calculates the correlation between the acquired set of difference signals Bd1 and the comparison waveform Wd2. When the first sampling number is any of 10 to 12, the determination unit 46 acquires four differential signals Bd1 that are continuous over the next sequence.

When the calculated correlation value is larger than the predetermined threshold value Y1, the determination unit 46 determines that the corresponding pair is a differential signal based on the radio wave transmitted from the radio wave sensor 101B, and the first sampling in the pair of the differential signal Bd1. A number (hereinafter, also referred to as a start number) and a sampling number at the end (hereinafter, also referred to as an end number) are stored.

Then, when a plurality of sets of start numbers and end numbers stored in the interference wave detection process 1 match in each of a plurality of sequences, the determination unit 46 receives its own radio wave from the radio wave sensor 101B. And outputs the determination result including the information indicating the existence of the radio wave and each stored sampling number to the control unit 4.

FIG. 11 is a diagram showing an example of correlation values calculated in the radio wave sensor according to the embodiment of the present invention. In FIG. 11, the horizontal axis represents the last sampling number, and the vertical axis represents the frequency Fb and the correlation value of the differential signal in order from the top of the paper.

With reference to FIG. 11, the determination unit 46 determines that there is a radio wave from the radio wave sensor 101B because the correlation value of the pair of difference signals Bd1 having the end number of 10 is larger than the predetermined threshold value Y1 in the plurality of sequences. The judgment result including the information and the start number 7 and the end number 10 is output to the control unit 4.

When the correlation value larger than the threshold value Y1 is calculated in each sequence, the determination unit 46 is not limited to the configuration in which the transmission timing of the interference wave is periodic, and the correlation value larger than the threshold value Y1 is one or more. A configuration may be used in which the transmission timing of the interference wave is determined to be periodic when it is calculated for every sequence or once for every one or more detection periods.

In this way, the determination unit 46 determines whether or not the transmission timing of the interference wave is periodic, thereby determining whether or not the device that is the transmission source of the interference wave is a device that is fixedly grounded. Can be judged.

[Modification of interference wave detection processing 1]
For example, the determination unit 46 determines the cycle of the radio wave included in the received radio wave based on whether the received radio wave satisfies a predetermined condition regarding another device that transmits the radio wave that is the interference wave with respect to the radio wave transmitted by the transmission unit 1. Make sex decisions.

Specifically, for example, the administrator registers information such as the timing of the radio wave transmitted from the radio wave sensor 101B and the distance between the radio wave sensor 101A and the radio wave sensor 101B in the memory 41 in advance.

The judgment unit 46 judges the periodicity of the radio waves included in the received radio waves, based on the information registered in the memory 41, for example.

The determination unit 46 determines the reception timing of the radio wave transmitted from the radio wave sensor 101B in its own radio wave sensor 101A based on the timing of the radio wave transmitted from the radio wave sensor 101B and the distance between the radio wave sensor 101A and the radio wave sensor 101B. presume.

The judgment unit 46 acquires from the memory 41, for example, a set of difference signals Bd1 having sampling numbers 1 to 12 corresponding to a certain sequence.

When the value of the frequency component of the difference signal Bd1 of the sampling number corresponding to the estimated reception timing is negative among the acquired difference signals Bd1, the determination unit 46 transmits the difference signal Bd1 from the radio wave sensor 101B. It is determined that the difference signal is based on the radio wave.

In addition, when the value of the frequency component of the difference signal Bd1 having a sampling number different from the sampling number corresponding to the estimated reception timing is a negative value among the acquired difference signals Bd1, the determination unit 46 has its own clock signal CS. Information indicating that the frequency error is large may be output to the control unit 4.

The control unit 4 creates an adjustment instruction for adjusting the frequency of the clock signal CS according to the information received from the determination unit 46, and outputs the adjustment instruction to the clock generation circuit 6.

The clock generation circuit 6 adjusts the frequency of the clock signal CS according to the adjustment instruction received from the control unit 4.

Further, the control unit 4 is not limited to the above-described timing, distance, and the like, and is configured to make a determination regarding the periodicity of the radio wave included in the received radio wave based on the characteristics of the received radio wave such as the frequency sweep direction and the frequency sweep width. May be.

[Interference wave detection processing 2]
FIG. 12 is a diagram showing another example of each waveform of the received radio wave and the differential signal in the radio wave sensor according to the embodiment of the present invention. In FIG. 12, the horizontal axis represents time, and the vertical axis represents the frequencies Ft and Fr of the transmission radio wave and the reception radio wave and the frequency Fb of the differential signal in order from the upper side of the paper. The frequency Ft of the transmitted radio wave is represented by the solid line, and the frequency Fr of the received radio wave is represented by the broken line.

Further, in FIG. 12, among the sampling timings of each sequence, the digital difference signal Bd1 at the sampling timing for each cycle Tc of the divided clock signal CS is indicated by a white circle. The sampling timing for each cycle Tc in each sequence is represented by sampling numbers 1 to 12 indicating the sampling order.

FIG. 12 shows the frequencies Ft and Fr of the transmission radio wave and the reception radio wave and the frequency Fb of the differential signal when the reception radio wave contains an interference wave in the guard period in the radio wave sensor 101.

With reference to FIG. 12, the radio wave sensor 101 receives, for example, a radio wave having a waveform that is not registered with itself during the guard period Gp.

The determining unit 46 performs the interference wave detection process 2 when the calculated correlation value of each set in the interference wave detection process 1 is less than or equal to a predetermined threshold value Y1, for example.

That is, for example, the determination unit 46 compares, in the sequence Seq1, a set of differential signals Bd1 having consecutive negative frequency component values included in a set of a plurality of consecutive differential signals Bd1 corresponding to the acquired guard period with a comparison waveform. It is saved in the memory 41 as Wd3.

Specifically, the determination unit 46 stores the set of differential signals Bd1 with sampling numbers 7 to 10 shown in FIG. 12, for example, in the memory 41 to register each set of differential signals Bd1 as the comparison waveform Wd3. To do.

Then, the determination unit 46 uses the registered comparison waveform Wd3 to calculate the correlation with the waveform of the differential signal Bd1 in the set of differential signals Bd1 after the sequence Seq2, and the correlation is included in the received radio wave based on the calculated correlation. Determines the periodicity of radio waves.

Specifically, for example, the determination unit 46 acquires a set of four consecutive differential signals Bd1 from the memory 41 while shifting the sampling number by 1, and correlates the acquired set of differential signals Bd1 with the comparison waveform Wd3. To calculate.

FIG. 13 is a diagram showing another example of the correlation value calculated by the radio wave sensor according to the embodiment of the present invention. In FIG. 13, the horizontal axis represents the last sampling number, and the vertical axis represents the frequency Fb and the correlation value of the differential signal in order from the top of the paper.

With reference to FIG. 13, the determination unit 46 determines that there is an interference wave because the correlation value of the waveform of the difference signal Bd1 having the end number of 10 is larger than the predetermined threshold value Y2 in a plurality of sequences after the sequence Seq2. The judgment result including the information and the start number 7 and the end number 10 is output to the control unit 4.

[Modification of interference wave detection processing 2]
FIG. 14 is a diagram showing an example of each waveform of a received radio wave and a differential signal in the radio wave sensor according to the embodiment of the present invention. In FIG. 14, the horizontal axis represents time, and the vertical axis represents the frequencies Ft and Fr of the transmission radio wave and the reception radio wave and the frequency Fb of the differential signal in order from the upper side of the paper. The frequency Ft of the transmitted radio wave is represented by the solid line, and the frequency Fr of the received radio wave is represented by the broken line.

Also, in FIG. 14, among the sampling timings of each sequence, the digital difference signal Bd1 at the sampling timing for each cycle Tc of the divided clock signal CS is shown by a white circle. The sampling timing for each cycle Tc in each sequence is represented by sampling numbers 1 to 12 indicating the sampling order.

Referring to FIG. 14, the radio wave sensor 101 receives the target reflected wave and the interference wave in the transmission period Tp.

In FIG. 14, since the target reflected wave and the interference wave are received at the same timing, two frequency components are obtained for the differential signal Bd1 having one sampling number.

The determination unit 46, for example, because the value of the frequency component of the difference signal Bd1 whose sampling number is 1 in each difference signal Bd1 acquired from the memory 41 is not zero, the target reflected wave is included in the radio wave received by the reception unit 2. It is determined that an interference wave that is a radio wave other than the above is included, and, for example, interference wave detection processing 2 is performed.

More specifically, the determining unit 46 determines that the interference signal is included in the period of the sampling numbers 12 to 3 because the value of the frequency component of the differential signal Bd1 having the sampling numbers of 1 to 3 is negative. to decide.

The determining unit 46 stores the difference signal Bd1 having the sampling number 12 to the difference signal Bd1 having the sampling number 3 in the next sequence in the memory 41, thereby registering the set of the difference signals Bd1 as the comparison waveform Wd4. Then, the registered comparison waveform Wd4 is used to calculate the correlation with the set of difference signals Bd1 of the next sequence and thereafter.

Specifically, for example, the determination unit 46 acquires a set of five consecutive difference signals Bd1 from the memory 41 while shifting the sampling number by 1, and correlates the acquired set of difference signals Bd1 with the comparison waveform Wd4. To calculate.

When the determination unit 46 determines that the radio waves included in the received radio waves have periodicity based on the calculated correlation, the information indicating the existence of the interference wave and the stored sampling number, that is, the start number 12 and the end number 4 are stored. The determination result including and is output to the control unit 4.

Note that the determination unit 46 may be configured to perform the interference wave detection processing 1 when it determines that the radio wave received by the reception unit 2 includes an interference wave that is a radio wave other than the target reflected wave.

The determination unit 46 may be configured not to perform the interference wave detection process 1 and the interference wave detection process 2. More specifically, for example, when the signal strength indicated by the value of the difference signal Bd1 acquired from the memory 41 is smaller than a predetermined threshold value, the determination unit 46 does not have to perform the interference wave detection process 1 and the interference wave detection process 2. Good.

[Adjustment of transmission timing]
The control unit 4 adjusts the transmission timing of radio waves by the transmission unit 1 based on the determination result of the determination unit 46. For example, the control unit 4 adjusts the transmission timing so that the radio wave is transmitted from the transmission unit 1 at a timing different from the transmission period of the interference wave.

More specifically, the control unit 4 acquires the start number and the end number included in the determination result received from the determination unit 46.

As an example, it is assumed that the control unit 4 receives the determination result including the start number 12 and the end number 3 from the determination unit 46.

Then, the control unit 4 determines whether to change the transmission timing of the radio wave by the transmission unit 1 based on the acquired start number and end number.

The control unit 4 determines that the transmission period Tp is the period from the start number 12 to the end number 3 because the transmission period Tp corresponding to the sampling numbers 1 to 4 includes the periods of the start number 12 and the end number 3, for example. It is decided to be a period that does not overlap with.

FIG. 15 is a diagram showing an example of a period that can be changed as a new transmission timing in the radio wave sensor according to the embodiment of the present invention. In FIG. 15, the horizontal axis represents time, and the vertical axis represents the frequencies Ft and Fr of the transmission radio wave and the reception radio wave and the frequency Fb of the differential signal in order from the upper side of the paper. The frequency Ft of the transmitted radio wave is represented by the solid line, and the frequency Fr of the received radio wave is represented by the broken line.

Further, in FIG. 15, the digital difference signal Bd1 at each sampling timing of each sequence in a certain sequence is indicated by a white circle. Each sampling timing is represented by a sampling number of 1 to 12 indicating the sampling order.

Referring to FIG. 15, in order that the transmission period Tp does not overlap with the period from the start number 12 to the end number 3, the sweep start of the changed transmission radio wave is performed at any timing of the sampling numbers 4 to 9. Just set it.

The control unit 4, for example, changes the start of the sweep of the transmitted radio wave to the timing of the

sampling number

5 or 9.

Specifically, the control unit 4 delays the transmission timing of the radio wave by the transmission unit 1 by 4 pulses or 8 pulses of the clock signal CS.

FIG. 16 is a diagram showing an example of how the radio wave transmission timing is changed in the radio wave sensor according to the embodiment of the present invention. In FIG. 16, the horizontal axis represents time and the vertical axis represents the level of each signal.

With reference to FIG. 16, the control unit 4 does not generate the trigger signal TS indicating the start of the next detection period after the end of the last sequence SeqM in a certain detection period, and then outputs the clock signal after the end of the sequence SeqM. After counting the rising edges of CS four times, the trigger signal TS is generated, and the generated trigger signal TS is output to the transmission unit 1 and the signal processing unit 5. As a result, the start timing of the next detection period is shifted to 5 cycles later.

FIG. 17 is a diagram showing an example of a target reflected wave and an interference wave after changing the transmission timing of the radio wave in the radio wave sensor according to the embodiment of the present invention. In FIG. 17, the horizontal axis represents time, and the vertical axis represents the frequencies Ft and Fr of the transmission radio wave and the reception radio wave and the frequency Fb of the differential signal in order from the upper side of the paper. The frequency Ft of the transmitted radio wave is represented by the solid line, and the frequency Fr of the received radio wave is represented by the broken line.

Also, in FIG. 17, the digital difference signal Bd1 at each sampling timing of each sequence is indicated by a white circle. The sampling timing in each sequence is represented by sampling numbers 1 to 12 indicating the sampling order.

Referring to FIG. 17, in the radio sensor 101, the timing of receiving the interference wave is changed from the period of sampling numbers 12 to 3 to the period of sampling numbers 8 to 11 by changing the transmission timing of the transmission radio wave.

As another example, the control unit 4 determines the determination result including the start number 12 and the end number 4 that overlap with the transmission period Tp and the determination result indicating the start number 8 and the end number 11 included in the guard period Gp. , The transmission period Tp is set to a period that does not overlap the period from the start number 12 to the end number 4 and the period from the start number 8 to the end number 11.

Specifically, for example, the control unit 4 changes the start of sweeping the transmission radio wave to a period in which the sampling number is 5 to 7.

Further, the control unit 4 is not limited to the configuration of changing the sweep start timing as the adjustment of the radio wave transmission timing, and may change the transmission period Tp by shortening the sweep time Ts, for example.

[Non-detection period]
For example, the control unit 4 further sets one or a plurality of detection periods in which the detection process is performed and a non-detection period in which the detection process is not performed and radio waves are not transmitted from the transmission unit 1.

More specifically, for example, the control unit 4 sets a non-detection period Tn in which no detection process is performed and no radio wave is transmitted from the transmission unit 1 after the end of one or more detection periods.

With this, the determination unit 46 can easily detect an interference wave that is difficult to detect, an interference wave received at the same timing as the target reflected wave in the detection period, an interference wave with low power, and the like.

Specifically, after repeating the detection period a predetermined number of times, the control unit 4 outputs the trigger signal TS generated at the start timing of the next sequence to the signal processing unit 5. That is, the controller 4 does not output the generated trigger signal TS to the transmitter 1. As a result, the transmission of the radio wave from the transmitter 1 is stopped, so that the radio wave sensor 101 can more efficiently detect the interference wave without receiving the target reflected wave.

Then, the control unit 4 restarts the output of the generated trigger signal TS to the transmission unit 1 after the non-detection period Tn has elapsed.

The judgment unit 46 judges the periodicity of the radio wave received by the reception unit 2 in the non-detection period Tn.

More specifically, the determination unit 46 performs at least one of the interference wave detection process 1 and the interference wave detection process 2 in the non-detection period Tn, and determines that the radio wave included in the received radio wave has periodicity. , And outputs the determination result to the control unit 4.

FIG. 18 is a diagram showing an example of each waveform of a received radio wave and a differential signal in the radio wave sensor according to the embodiment of the present invention. 18, the horizontal axis represents time, and the vertical axis represents the frequency Fr of the received radio wave and the frequency Fb of the differential signal in order from the upper side of the paper.

Further, in FIG. 18, the digital difference signal Bd1 at each sampling timing of each sequence is indicated by a white circle. The sampling timing in each sequence is represented by sampling numbers 1 to 12 indicating the sampling order.

Referring to FIG. 18, the radio wave sensor 101 receives the interference wave during the non-detection period Tn during the period of sampling numbers 1 to 4 corresponding to the transmission period Tp. The determining unit 46 determines that the radio wave received during the period includes an interference wave, for example, by calculating the correlation between the waveform of the above-described difference signal Pd2 and the waveform of the difference signal Bd1 based on the interference wave. You can

The control unit 4 adjusts the transmission timing of the radio wave by the transmission unit 1 based on the determination result received from the determination unit 46 in the non-detection period Tn.

[Operation flow]
Each device in the safe driving support system 301 includes a computer including a memory, and an arithmetic processing unit such as a CPU in the computer reads and executes a program including some or all of the steps of the following flowchart from the memory. To do. The programs of these plural devices can be installed from the outside. The programs of these plural devices are distributed in a state of being stored in a recording medium.

FIG. 19 is a flowchart that defines an operation procedure when the radio wave sensor according to the embodiment of the present invention determines the periodicity of received radio waves and adjusts the transmission timing of its own radio waves.

Referring to FIG. 19, first, the radio wave sensor 101 transits to the detection period (step S101) and determines whether or not an interference wave is received (step S102).

When the radio wave sensor 101 does not receive the interference wave (NO in step S102), it waits until the next detection period (step S105).

On the other hand, when the radio wave sensor 101 determines that the interference wave is received (YES in step S102), the radio wave sensor 101 determines whether or not the interference wave is received in the transmission period Tp of its own transmission radio wave (step S103). ).

When the radio wave sensor 101 receives an interference wave at a timing different from the transmission period Tp (NO in step S103), the radio wave sensor 101 waits until the next detection period (step S105).

On the other hand, when the radio wave sensor 101 receives the interference wave in the transmission period Tp (YES in step S103), it adjusts the transmission timing of its own transmission radio wave (step S104) and waits until the next detection period (step S104). S105).

The radio wave sensor 101 waits until the next detection period (NO in step S105) until the predetermined number of detection periods elapses (step S105).

On the other hand, the radio wave sensor 101 transitions to the non-detection period Tn (step S106) when a predetermined number of detection periods have passed (YES in step S105).

Next, the radio wave sensor 101 determines whether or not an interference wave is received in the non-detection period Tn (step S107).

When the interference wave is not received (NO in step S107), the radio wave sensor 101 continues to monitor the interference wave (step S110).

On the other hand, when the radio wave sensor 101 determines that the interference wave is received (YES in step S107), the radio wave sensor 101 determines whether the interference wave is received at the transmission timing of its own radio wave (step S108).

The radio wave sensor 101 continues to monitor the interference wave when the interference wave is received at a timing different from the transmission period Tp (NO in step S108) (step S110).

On the other hand, when the radio wave sensor 101 is receiving the interference wave in the period corresponding to the transmission period Tp (YES in step S108), the radio wave sensor 101 adjusts the transmission timing of its own radio wave (step S109) and continues to monitor the interference wave. (Step S110).

Then, when the non-detection period Tn ends (YES in step S110), the radio wave sensor 101 transitions to the detection period (step S101).

FIG. 20 is a flow chart that defines an operation procedure when the determination unit in the radio wave sensor according to the embodiment of the present invention determines the periodicity of the received radio wave. FIG. 20 shows in detail the operation of steps S102 and S107 of FIG.

Referring to FIG. 20, first, the determination unit 46 acquires a set of each differential signal Bd1 from the memory 41 (step S201), and determines whether the acquired set includes the differential signal Bd1 based on the interference wave. Yes (step S202).

When the determination unit 46 determines that the acquired pair includes the differential signal based on the interference wave (YES in step S202), the correlation between the comparative waveform registered in the memory 41 and the waveform of the differential signal Bd1 is determined. It is calculated (step S203).

Next, when the calculated correlation value is less than or equal to the predetermined threshold value (NO in step S204), the determination unit 46 registers the waveform of the difference signal Bd1 as a comparison waveform in the memory 41 (step S208).

On the other hand, when the calculated correlation value is larger than the predetermined threshold value (YES in step S204) and the state of calculating the correlation value larger than the threshold value periodically occurs (YES in step S205), the determination unit 46 acquires It is determined that the set of difference signals Bd1 includes the difference signal based on the interference wave (step S206).

Further, when the state of calculating the correlation value larger than the threshold value does not occur periodically (NO in step S205), the determination unit 46 determines that the differential signal Bd1 does not include the differential signal based on the interference wave (step S205). Step S207).

In the radio wave sensor according to the embodiment of the invention, the control unit 4 is configured to set the non-detection period Tn, but the configuration is not limited to this. The control unit 4 may have a configuration in which the non-detection period Tn is not provided.

In the radio wave sensor according to the embodiment of the invention, the determination unit 46 is configured to determine whether the transmission timing of the radio wave included in the received radio wave is periodic, but the configuration is not limited to this. is not. The determination unit 46 may be configured to determine the possibility that the transmission timing of the radio waves included in the received radio waves is periodic.

Further, in the radio wave sensor according to the embodiment of the present invention, the determination unit 46 is configured to make a determination regarding the periodicity of the radio wave received in the guard period Gp, but the configuration is not limited to this. The determination unit 46 may be configured to make a determination regarding the periodicity of only the radio waves received in the transmission period Tp.

By the way, beyond the technology described in Patent Document 1, a technology capable of avoiding radio wave interference and detecting a target object better is desired.

Therefore, in the radio wave sensor according to the embodiment of the present invention, the transmission unit 1 transmits a radio wave. The receiver 2 receives a radio wave including a reflected wave of the radio wave transmitted by the transmitter 1. The detection processing unit 7 detects an object based on the received radio wave that is the radio wave received by the reception unit 2. The determination unit 46 determines the periodicity of received radio waves. The control unit 4 adjusts the transmission timing of radio waves by the transmission unit 1 based on the determination result of the determination unit 46.

Further, in the safe driving support system according to the embodiment of the present invention, the signal control device 151 creates information regarding safe driving support based on the detection result received from the radio wave sensor 101, and transmits the information to the wireless transmission device 152. .. The wireless transmission device 152 transmits a radio wave including the information received from the signal control device 151.

In this way, by the configuration that makes the determination regarding the periodicity of the received radio wave, it is possible to determine whether or not the device that is the transmission source of the received radio wave is a device that is fixedly installed. The influence of radio waves from non-fixed devices can be suppressed, and more accurate transmission timing control can be performed. Further, the periodicity of the received radio wave can be determined without demodulating the signal included in the received radio wave.

Therefore, the radio wave sensor and the safe driving support system according to the embodiment of the present invention can avoid the radio wave interference and detect the object better. Specifically, when another radio wave sensor or the like is present near its own radio wave sensor, it is possible to avoid the interference of the radio waves transmitted by the both radio wave sensors and detect the target object better.

Moreover, in the radio wave sensor according to the embodiment of the present invention, the transmission unit 1 transmits radio waves intermittently. The determination unit 46 determines the periodicity of the radio wave received by the reception unit 2 during the non-transmission period of the radio wave by the transmission unit 1.

Further, in the radio wave sensor according to the embodiment of the present invention, the control unit 4 sets a detection period in which the detection process is performed and a non-detection period in which the transmission unit 1 does not transmit the radio wave. The determination unit 46 determines the periodicity of the radio wave received by the reception unit 2 during the non-detection period.

As described above, due to the configuration in which the non-detection period Tn is provided, it is difficult to detect in the detection period, for example, radio waves from other devices that receive at the timing when the radio wave reflected by the target object is received. Can be easily detected.

Further, in the radio wave sensor according to the embodiment of the present invention, the determination unit 46 calculates the correlation between the radio wave transmitted by the transmission unit 1 and the received radio wave, and makes the determination regarding the periodicity based on the calculated correlation. ..

Further, in the radio wave sensor according to the embodiment of the present invention, the determination unit 46 determines whether the received radio wave satisfies a predetermined condition regarding another device that transmits a radio wave that becomes an interference wave with respect to the radio wave transmitted by the transmission unit 1. Based on the above, the judgment regarding the periodicity is made.

As described above, for example, the radio wave sensor 101 performs a cycle based on characteristics other than the waveform of the received radio wave, such as the transmission timing of the radio wave of another device that transmits an electric wave that becomes an interference wave of the received radio wave and the distance to the device. With the configuration for determining the sex, it is possible to determine the periodicity of the received radio waves by using the measurement results of the received radio waves that are received less frequently. Thereby, the periodicity of the received radio wave can be determined in a shorter time.

The above embodiments should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and is intended to include meanings equivalent to the claims and all modifications within the scope.

The above description includes the following additional features.
[Appendix 1]
A transmitter that transmits radio waves,
A receiver that receives radio waves,
A detection unit that performs a detection process of detecting an object based on a received radio wave that is a radio wave received by the reception unit,
A determination unit that determines the periodicity of the received radio wave,
An adjusting unit that adjusts the transmission timing of the radio wave by the transmitting unit based on the determination result of the determining unit,
The determination unit determines whether the transmission timing of the received radio wave is periodic,
The adjustment unit adjusts the transmission timing so that the radio wave is transmitted from the transmission unit at a timing different from the transmission period of the reception radio wave,
The radio wave sensor does not have a function of modulating and demodulating radio waves.

1 transmitter 2 receiver 3 differential signal generator 4 controller (adjustment unit and setting unit)
5 signal processing unit 6 clock generation circuit 7 detection processing unit (detection unit and moving speed acquisition unit)
21 transmitting antenna 22 power amplifier 23 directional coupler 24 VCO
25 voltage generator 26 switch 31 receiving antenna 32 low noise amplifier 33 mixer 34 IF amplifier 35 low pass filter 36 A / D converter (ADC)
41 memory 42 FFT processing unit 43 FMCW processing unit 44 pattern signal acquisition unit 45 addition unit 46 judgment unit 101 radio wave sensor 141 relay device 151 signal control device 152 wireless transmission device 153 antenna 161 pedestrian traffic light 301 safe driving support system

Claims

A transmitter that transmits radio waves,
A receiver for receiving radio waves including reflected waves of the radio waves transmitted by the transmitter,
A detection unit that performs a detection process of detecting an object based on a received radio wave that is a radio wave received by the reception unit,
A determination unit that determines the periodicity of the received radio wave,
A radio wave sensor, comprising: an adjustment unit that adjusts the transmission timing of the radio wave by the transmission unit based on the determination result of the determination unit.
The transmitting unit transmits radio waves intermittently,
The radio wave sensor according to claim 1, wherein the determination unit makes a determination regarding periodicity of the received radio wave in a non-transmission period of the radio wave by the transmission unit.
The radio wave sensor further includes
A detection period for performing the detection process, and a setting unit for setting a non-detection period in which the detection unit is not performed and radio waves are not transmitted from the transmission unit,
The radio wave sensor according to claim 1, wherein the determination unit makes a determination regarding periodicity of the received radio wave in the non-detection period.
The determination unit calculates the correlation between the radio wave transmitted by the transmission unit and the reception radio wave, and makes a determination regarding the periodicity based on the calculated correlation. The radio wave sensor according to item 1.
The determination unit determines the periodicity based on whether or not the received radio wave satisfies a predetermined condition regarding another device that transmits a radio wave that becomes an interference wave with respect to the radio wave transmitted by the transmission unit, The radio wave sensor according to any one of claims 1 to 4.
Radio sensor,
Based on the detection result of the radio wave sensor, a signal control device that creates and transmits information regarding safe driving support,
A wireless transmission device that transmits a radio wave including the information received from the signal control device,
The radio wave sensor is
A transmitter that transmits radio waves,
A receiver for receiving radio waves including reflected waves of the radio waves transmitted by the transmitter,
A detection unit that performs a detection process of detecting an object based on a received radio wave that is a radio wave received by the reception unit,
A determination unit that determines the periodicity of the received radio wave,
A safe driving support system, comprising: an adjusting unit that adjusts the transmission timing of radio waves by the transmitting unit based on the determination result of the determining unit.