JP2019219215A - Moving object detection sensor - Google Patents

Abstract

To provide a moving object detection sensor with which it is possible to detect a moving object with high sensitivity by a simple configuration.SOLUTION: A moving object detection sensor 10 comprises a distributor 12 for distributing a reference signal as two signals, a receive antenna for receiving one of reference signals via a cable 13 that are distributed by the distributor 12, level adjustment means 14, and a phase shifter 15 for cyclically changing the phase of the reference signal. The other of the reference signals distributed by the distributor 12 is radiated toward an external detection space. The level adjustment means 14 and the phase shifter 15 are adjusted in advance by a computer 22 so that a minimum level signal cyclically formed as the two signals distributed while no moving object exists in the detection space and an ambient environment does not change cancel out each other, is obtained as a steady signal pattern by a received level detector 17. A disturbance pattern signal synthesized from a reflected signal temporally caused to occur by entry of a moving object into the external detection space and the reference signal routed via cable by a synthesizer 16 is compared with the steady signal pattern by the computer 22, and the moving object having entered the detection space is detected.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a moving object detection sensor that detects movement of a moving object.

  Conventionally, detection sensors for detecting moving objects such as pedestrians and bicycles have been developed. An example of such a sensor is disclosed on the Internet as an eco-counter ("Non-Patent Document 1").

  According to Patent Literature 1, an eco-counter is installed on a lane dedicated to a moving body or the like on a road where many moving bodies pass. Here, the number of passages of the moving body is counted by analyzing a pyrosensor that detects heat radiated from a human body and a magnetic signal generated by a wheel of a bicycle.

Eco Counter (http://www.eco-counter.com/)

  A conventional sensor for detecting a moving object has been configured as described above. However, in such a sensor, it was necessary to provide the sensor in a lane dedicated to the moving object. Further, in such a sensor, it is generally considered that a detection coil or the like is embedded in a road. However, because of this, digging the road is troublesome and expensive, and has no merit.

  The present invention has been made in view of the above-described problems, and has as its object to provide a moving object detection sensor that can detect a moving object with a simple configuration at low cost.

  A moving object detection sensor according to the present invention includes a reference signal generation unit that generates a reference signal, a distributor that distributes the reference signal as two signals, and one of the reference signals distributed by the distributor, which is connected to an external device. A transmitting antenna that radiates toward the detection space, a receiving antenna that is placed at a position distant from the transmitting antenna, receives a reference signal transmitted from the transmitting antenna, and that has passed through the detection space, and a reference signal distributed by the distributor. A phase shifter for periodically changing the other phase, level adjusting means connected to the phase shifter for attenuating to a level of a reference signal passing through a detection space received by the receiving antenna, and detecting the signal received by the receiving antenna. A reference signal that has passed through the space, a combiner that combines the signal that has passed through the phase shifter and the level adjustment unit, and a detection unit that detects the level of the signal combined by the combiner, The phaser and the level adjustment means are such that the moving object does not exist in the detection space and the surrounding environment does not change, and the synthesized signal in the synthesizer cancels out when the phases of the signals are relatively opposite to each other, and becomes minimum. The detection means is adjusted so as to periodically detect a waveform having a dip indicating the minimum level, and the waveform having the dip is repeatedly observed as a steady state detection waveform when no moving object is present in the detection space, The signal radiated into the detection space by the external moving body that has entered the receiver receives a change in phase and level and is received by the receiving antenna. The phase and level of the signal detected by the means are affected by an external moving body, and the level and phase of the dip change from the steady state detection waveform. Based on a comparison between the waveform and the steady state detected waveform, for detecting a moving object has entered the detection space.

  Preferably, a plurality of receiving antennas are provided in the traveling direction of the moving body or in the direction that traverses the space.

  More preferably, the receiving antenna is provided on a curb constituting a road on which the moving object moves.

  The type of the moving object may be determined based on a comparison between the changed waveform detected by the detection means and the steady state detection waveform.

  A signal radiated into the detection space by an external moving body that has entered the detection space is received by a receiving antenna after receiving a change in phase and level, and is synthesized by a synthesizer with a reference signal passed through a phase shifter and the level adjusting means. The phase and level of the signal detected by the detecting means are affected by the external moving body, and the level and phase of the dip change from the steady state detection waveform. A moving body that has entered the detection space is detected based on a comparison with the state detection waveform.

  As a result, it is possible to provide a moving object detection sensor capable of detecting various types of moving objects with high sensitivity, simple configuration, and high sensitivity in multiple directions.

FIG. 2 is a block diagram illustrating the principle of the present invention. FIG. 1 is a block diagram showing an overall configuration of an embodiment of the present invention. It is a figure which shows the concrete waveform of the dip point which attenuated deeply. FIG. 4 is a diagram illustrating a waveform measured by a measurement unit. It is a figure showing an example of installation of a mobile object detection sensor.

  Hereinafter, an embodiment of a moving object detection sensor according to the present invention will be described with reference to the drawings.

  The basic configuration of the present invention will be described with reference to FIG. FIG. 1 is a block diagram illustrating a basic configuration of the present invention.

  A moving object detecting unit 10 which is a basic configuration of the moving object detecting sensor 10 according to the present invention includes a reference signal generating unit 11 for generating a reference signal, and a distribution for dividing the signal generated by the reference signal generating unit 11 into two paths. Level adjuster 14, phase shifter 15, and combiner 16 connected to distributor 12 via cable 13; receive level detector 17 connected to combiner 16; And a receiving antenna 19 connected to the combiner 16 and receiving a signal from the outside. The mobile antenna detecting unit 10 is configured by these components. I do.

  One of the signals distributed by the distributor 12 is sent to a level adjusting means 14 via a cable, where the signal is adjusted in level and sent to a phase shifter 15, where a signal having a predetermined phase changed in a predetermined time is converted. It is prepared and output to the synthesizer 16.

  The other signal distributed by the distributor 12 is output from the transmitting antenna 18 to the detection space as it is. The reference signal output from the transmitting antenna 18 is reflected by a moving object 30 such as a pedestrian or a bicycle, and the amplitude and phase are modulated and input to the receiving antenna 19.

  In this embodiment, first, a case where only a direct wave from the transmitting antenna and a reflected signal from a building or the like from the surrounding environment are used in a state where the moving object is not present in the detection space, which is a premise for detecting the moving object. Prepare the traffic light. This preparation method will be described later.

  As will be described later, the level is adjusted by the level adjusting means 14 and the phase shifter 15 so that a deeply attenuated point (dip) is always generated in a state where there is nothing around the receiving antenna 19 in the time range in one phase sweep. I do. This dip indicates that the signals on the two paths have substantially the same level and cancel each other at the timing of the opposite phase of the phase shifter 15.

  Here, a specific waveform will be described for easy understanding. FIG. 3 is a waveform showing this state. For example, when no moving object is present in the detection space, dip data as indicated by a solid line 52 is obtained. The horizontal axis is the phase and the vertical axis is the signal of the detector, which is represented by an exponential scale level. Assuming that -10 at the top of the vertical axis is signal intensity 1, -60 below five graduations is equivalent to 1 / 100,000. The ratio between the level of the high level portion of the waveform and the level of the dip position is 10,000 or more. Originally, a clear dip as shown here may not occur due to circuit noise and spatial noise, but the waveform data when noise is also considered is slightly higher due to the noise, as indicated by a dotted line 52. It is calculated to move. Normally, the influence of noise in the circuit must be designed to be lower than required for the sensor.

  In this state, when the moving body 30 enters the detection space and a signal due to the reflection of the moving body having a higher noise level is generated, the signal is input to the receiving antenna 19 and is synthesized by the synthesizer 16, and the level and phase relationship changes, The signal representing the dip shifts in the time direction and becomes smaller (represented by a signal 53), or the level rises without being displaced in the time direction (represented by a signal 54), and the position of the dip changes. Can be detected. The signal 51 shows a waveform in a space without noise.

  Next, a moving object detection sensor according to this embodiment will be described. FIG. 2 is a block diagram showing the overall configuration of the moving object detection sensor according to the present embodiment. Referring to FIG. 2, moving object detection sensor 20 includes two sets of moving object detection units 10 described above.

  Specifically, the moving object detection sensor 20 includes a control unit 21 that controls the entire moving object detection sensor 20, a first moving object detecting unit 10a, and a second moving object detecting unit 10b.

  The first path and the second path have exactly the same mechanism, and differ only in the positional relationship between the receiving antennas 19a and 19b with respect to the transmitting antenna 18 on the front side or the rear side in the moving direction of the mobile unit 30. The reference signal generator 11 and the transmitting antenna 18 are common and have a configuration in which the number of distributions of the distributor 12 is increased.

  Referring to FIG. 2, control unit 21 includes a computer (PC) 22, a measuring unit 23 connected to computer 22, a controller 24 connected to measuring unit 23, and a phase shifter connected to controller 24. It includes a control signal generator 25, a transmitting unit 11 connected to the controller 24 for outputting a reference signal, a distributor 12, and a transmitting antenna 18 connected to the distributor 12.

  The first mobile unit detector 10a is connected to the first level adjuster 14a, the first phase shifter 15a, the first combiner 16a, and the first combiner 16a, which are connected to the distributor 12 via a cable. And a first reception antenna 19a and a first reception level detector 17a.

  The second mobile unit detector 10b is connected to the second level adjuster 14b, the second phase shifter 15b, the second combiner 16b, and the second combiner 16b connected to the distributor 12 via a cable. And a second reception antenna 19b and a second reception level detector 17b.

  The phase shifters 15a and 15b are composed of a semi-fixed phase shifter having a variable range of 180 degrees or more and two types of phase shifters that receive a signal from the phase shifter control signal generator 25 and change by 180 degrees or more. As described above, the phase is changed. The level is adjusted to substantially the same level as that of the signals received by the receiving antennas 19a and 19b by the level adjusting means 14a and 14b, and the phases are always reversed in the time change range of the phase shifter control signal generator 25. Offset each other and cancel each other out. For example, the phase shifter control signal is a signal whose voltage changes over time, such as a triangular wave or a sawtooth wave, and changes back from -90 degrees to +90 degrees and from +90 degrees to -90 degrees. The signal of the level change including the dip is treated as horizontal axis = phase position = time position (see FIG. 4).

  The calculation logic for obtaining this waveform is as follows. An airborne signal of the receiving antenna 19 when the moving object is at infinity from the transmitting antenna 18 and the receiving antenna 19, and a reference signal whose phase is temporally changed so as to balance the signal and cancel to zero. Are synthesized. The composite value periodically changes from twice to zero. The level is treated as a logarithm, and the doubling of the composite value is +6 dB, the attenuation point of the cancellation point 0 is -∞dB in theory, which is the detection sensitivity limit or the noise level. In this state, a reflected signal from the moving object is added when the moving object enters nearby. The strength of the signal reflected by the moving object is affected by the amount of return of the reflected signal of the moving object and the amount of phase shift related to the ratio of wavelength to distance and the amount of attenuation due to the square of the signal path distance.

  When the moving object is at infinity, the combiners 16a and 16b receive the signal via the external detection space, and the other of the reference signals distributed by the distributor 12 is received via the detection space. The signal is phase-shifted to a phase of (0 to 180) ± 90 degrees or more and attenuated to substantially the same level by the synthesizers 16a and 16b, and the level of the signal is detected. The waveform is output as a waveform having the above-mentioned dip whose level is attenuated. This waveform is made to be understood by the steady state data (steady state detection waveform) and the judgment system mounted on the computer 22. The computer 22, which understands this, reflects a part of the reference signal transmitted through the space due to the invasion of the moving object from the infinity to the vicinity of the external space, and the slight level and phase of the signal passing through the previous space are changed. Since the data of the disturbed and distorted dip levels and positions of the waveforms of the signals synthesized by the synthesizers 16a and 16b are obtained, it is possible to detect that the moving object has entered. It is easily understood that the waveform has a different level of change depending on the magnitude of the reflected signal. The change in the waveform of only the portion corresponding to the dip is a change that always occurs minutely due to noise, but the approaching level of the moving object can be estimated by increasing the level of change even a little. A change in a high level part means that the reflected signal is strong.

  The receiving antenna 19a receives a signal on the left side when viewed from the transmitting antenna 18. The receiving antenna 19b receives the right signal. This means that if the mobile object 30 such as a bicycle moves from left to right, it passes in front of the receiving antenna 19a → the transmitting antenna 18 → the receiving antenna 19b. The reception antenna 19a divides the reference signal of the transmitter 11 into the transmission antenna 18 and the reception antennas 19a and 19b, and the output signal is transmitted from the transmission antenna 18 and a part of the reference signal passing through the space is received. At the same time, the signal of the transmitter 11 is distributed, and is combined with the signal received by the receiving antenna 19a by the combiner 16a via the level adjusting means 14a and the phase shifter 15a, and is transmitted to the reception level detector 17a. Is entered. The same applies to the right side.

  When a moving object such as a bicycle enters from a distance on the left, the bicycle reflects radio waves and changes the normal state. This change results in a change in the phase and the level of the synthesized signal, and the dip that has been made in a normal state swings left and right, the dip becomes shallow, and the dip becomes deep. This change also occurs with a delay on the right receiving antenna, and the change is observed to propagate from left to right. If the bicycle moves in reverse, it will change from right to left.

  Next, the waveform measured by the measurement unit 23 will be described. FIG. 4 is a diagram showing a waveform actually measured, wherein the horizontal axis represents time and the vertical axis represents amplitude, and basically shows the same contents as FIG. In the figure, a range surrounded by a center frame 40 is a single phase sweep range, and a time range thereof corresponds to a phase of 0 to 180 degrees. The other range is the same alias signal. This is displayed because the output signal of the phase shifter control signal generator 25 is a triangular wave. This is due to the difference between the rising time zone and the falling time zone of the triangular wave. Either signal or both may be adopted as the signal. In the case of a sawtooth wave, the waveform period can be shortened as a whole by using a waveform portion having a gentle slope.

  Here, a signal 41 received by the first mobile unit detection unit 10a and a signal 42 received by the second mobile unit detection unit 10b are displayed.

  Next, the detection operation will be described. When a moving object such as a person or a bicycle enters a measurement range (a range surrounded by the first moving object detecting unit 10a and the second moving object detecting unit 10b) within the frame 40, the dip moves right and left or becomes shallow. Or become. The two synthesized signals 41 and 42 react alternately in the order in which a moving object or a person enters the measurement range. This reaction is determined by the computer 21 as data, and a moving body or a person is determined.

  Specifically, a moving object, a person, or both are distinguished by learning the waveform of a signal when a moving object or a person having different electrical properties enters. The method of changing the waveform by the moving object is accumulated as big data, and the difference in the change depending on the components of the moving object is learned by deep learning, so that it is possible to discriminate a person, a bicycle, and the like, to estimate a plurality of passes, a speed, and the like.

  This phase sweep is preferably repeated several times or more while the moving object passes through the detection space of the moving object detection sensor 10. This is because, by repeating in several tens of milliseconds, the moving object moving at high speed enters the detection space of the moving object detection sensor 10, and it can be detected that the change in the phase due to the change in the level of the reflected wave and the change in the distance further disturbs the balance. .

  It should be noted that a level change with respect to a single 180-degree phase change is repeatedly observed. The result changes depending on how much information on the level change resulting from the phase shift corresponding to FIG. 3 can be observed when a bicycle or the like passes. If the bicycle is traveling too fast, a single change may include both approach and separation. If you pass slowly, you can observe many changes when you are far, when you approach the most, when you leave. As a result, the speed can be observed.

  Next, a specific example of the arrangement of the moving object detection sensor will be described. FIG. 5 is a schematic diagram of a case where an element such as the control unit 21 of the moving object detection sensor 10 is provided inside a curb of a road as one example of a specific arrangement of the device of the moving object detection sensor 10. FIG. 5A is a perspective view showing three curbs 61 to 63, and FIG. 5B shows a roadway 56 and a sidewalk 57 separated from each other in FIG. 5A. In addition, here, the dimension of the curb is provided by arranging a standard length x width x height of 0.6 m x 0.2 m x 0.2 m and a length of 0.6 m continuously in the traveling direction. Is preferred.

  The curb 61 accommodates the element 58a, the curb 62 accommodates the element 59, and the curb 63 accommodates the element 58b. Here, the elements 58a and 58b house the first moving body detecting unit 10a and the second moving body detecting unit 10b, respectively, and the element 59 is the control unit 21.

  When the elements 58a, 58b, and 59 of the moving object detection sensor 10 are provided in such a configuration, the elements of the moving object detection system 10 can be installed only by replacing the curb without digging over the road.

  Note that this is merely an example of an installation method, and that any number of arbitrary methods can be used at any position near the moving body, such as the horizontal direction of the wall of the passage, the upper and lower sandwiches, and both sides of the passage, in any vicinity. Can be installed in the direction of In addition, an element of the control unit 21 for displaying a result or outputting an alarm or the like may be built in, or may be provided in a monitoring room (not shown). The connection between the control unit 21 and the element provided on the curb is made by wire or wirelessly.

  In addition, the frequency of the radio wave used here can be changed depending on the detection target, and in the case of a bicycle, 100 MHz to 300 MHz where metal interferes with most of the wheels, preferably a breakpoint of a weak signal in Japan. 320 MHz or less is appropriate. In addition, a plurality of frequencies can be configured at the same time, and can be added according to the target of the moving object. In addition, since the transmission frequency is a single frequency, the signal detection bandwidth can be narrowed to about the phase change speed, so that the sensitivity can be greatly increased. This system can use a medium whose signal phase can be controlled, and radio waves, magnetic fields, electric fields, or acoustic waves in any frequency band.

  In the above embodiment, a specific frequency of 100 MHz to 300 MHz affecting the wheels of the bicycle is radiated into the space, and the reflected radio wave and the phase sweep signal of the component (direct wave) hardly affected by the reflection are used. The fixed-frequency phase sweep method was used to create a phenomenon in which the synthesized wave strongly cancels out at a certain phase of the signal passing through the cable.However, the invention is not limited to this, and a frequency sweep type receiver with a tracking generator radiated into space with radio waves. A similar dip can be obtained by using a system in which the strength of the signal and the signal passing through the cable are adjusted. Here, the tracking generator refers to a transmitter that generates a signal that exactly matches the reception frequency at which the reception frequency is swept.

  In the above-described embodiment, the case where one signal distributed by the distributor is sent to the level adjusting means by a cable is described. However, the present invention is not limited to this. May be transmitted to the level adjusting means by any method including transmission and reception of the information.

  The embodiments of the present invention have been described with reference to the drawings. However, the present invention is not limited to the illustrated embodiments. Various modifications and variations can be made to the illustrated embodiment within the same range as the present invention or within an equivalent range.

  DESCRIPTION OF SYMBOLS 10 Moving body detection part, 11 Reference signal generation part, 12 distributor, 13 cable, 14 level adjustment means, 15 phase shifter, 16 synthesizer, 17 reception level detector, 18 transmission antenna, 19 reception antenna, 20 mobile Detection sensor, 21 control unit, 22 computer, 23 measuring unit, 24 controller, 25 phase shifter control signal generator, 30 moving body, 58, 59 elements, 61, 62, 63 curb.

Claims (4)

A reference signal generator for generating a reference signal;
A distributor that distributes the reference signal as two signals;
A transmitting antenna for radiating one of the reference signals distributed by the distributor toward an external detection space;
A receiving antenna that is located at a position distant from the transmitting antenna, receives a reference signal transmitted from the transmitting antenna and passing through the detection space,
A phase shifter that periodically changes the other phase of the reference signal distributed by the distributor;
Level adjusting means connected to the phase shifter and attenuating to a level of a reference signal that has passed through the detection space and received by the receiving antenna,
A combiner that combines the reference signal received by the receiving antenna and passed through the detection space with a signal that has passed through the phase shifter and a level adjusting unit.
Detecting means for detecting the level of the signal synthesized by the synthesizer,
The phase shifter and the level adjusting unit cancel out a synthesized signal in the synthesizer when the phases of the signals are relatively opposite in a state where no moving object exists in the detection space and the surrounding environment does not change. It is adjusted to periodically detect a waveform having a dip indicating a minimum level by the detection means,
The waveform having the dip is repeatedly observed as a steady state detection waveform when no moving object is present in the detection space,
A signal radiated into the detection space by an external moving body that has entered the detection space is received by the reception antenna after receiving a change in phase and level, and the reference signal is transmitted through the phase shifter and the level adjustment unit. The phase and level of the signal synthesized by the synthesizer and detected by the detection means are affected by an external moving body, and the level and phase of the dip change from the steady state detection waveform. A moving object detection sensor that detects a moving object that has entered the detection space based on a comparison between the detected changed waveform and the steady state detection waveform. The moving object detection sensor according to claim 1, wherein a plurality of the receiving antennas are provided in a moving direction of the moving object or a direction that traverses a space. The moving object detection sensor according to claim 1, wherein the antenna is provided on a curb configuring a road on which the moving object moves. The moving object detection sensor according to claim 1, wherein the type of the moving object is determined based on a comparison between the changed waveform detected by the detection unit and the steady state detection waveform.

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