JP2008133585A - Automatic door sensor using radar, and its object detection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely identify only an approaching person, when the approaching person moving in the direction of approaching an automatic door, and a receding person moving in the direction of getting away from the automatic door exist in an automatic-door monitoring area. <P>SOLUTION: Radar 11 is used as a transceiver for the monitoring area which is set near the automatic door. The radar 11 comprises a transmission portion which sends out a microwave with predetermined frequencies, and a reception portion which receives a reflected wave from an object existing in the monitoring area. In the radar, first and second cymoscopes 121 and 122 are arranged in the reception portion in such a manner as to be isolated by λ/4 in a longitudinal direction when λ represents the wavelength of the microwave. An opening/closing control signal is output to the automatic door by detecting the object in the monitoring area, according to an Ich signal which is output from the front cymoscope 121, and a Qch signal which is output from the rear cymoscope 122. In this case, after a phase shifter 21 makes the phase of either of the Ich signal and the Qch signal deviate by +90° or -90° from that of the other signal, the Ich signal and the Qch signal are added or subtracted, so that only the approaching person can be surely identified. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an automatic door sensor using radar and an object detection method thereof, and more specifically, an approaching person who moves to a monitoring area of the automatic door in a direction approaching the automatic door and a leaving person who moves in a direction away from the automatic door. In the present invention, it is preferable that the approaching side can be identified.

  In many cases, the infrared method is adopted for the automatic door sensor, but in the infrared method, the movement of a person (object to be detected), that is, whether moving toward the door or moving away from the door Even patterns cannot be identified.

  Therefore, in recent years, an automatic door sensor using a radar capable of identifying a moving object pattern has been put into practical use. An example of the configuration will be described with reference to FIGS.

  First, as shown in FIG. 9, this type of automatic door sensor 10 has, as a basic configuration, a control unit including a radar (microwave transceiver) 11, a low-pass filter 12, an A / D converter 13, a microcomputer, and the like. 14 is provided.

  For example, the radar 11 transmits a microwave of several GHz to several tens of GHz and receives a reflected wave (Doppler frequency) from an object. Therefore, as shown in FIG. 10, for example, a dielectric oscillator 110 using a Gunn diode 111 as an oscillation source and a receiving unit 120 provided in the waveguide are provided.

  In this case, as the receiving unit 120, first and second detectors 121 and 122 each including, for example, a Schottky diode are used. The two detectors 121 and 122 are λ / 4 or λ / 4 + λ / 2n in the longitudinal direction in the waveguide, where λ is the wavelength of the microwave transmitted from the dielectric oscillator 110 (n is an arbitrary positive integer) ; 0, 1, 2,...) Spaced apart.

  Therefore, the rear second detector 122 outputs a signal that is 90 ° out of phase with respect to the front first detector 121. Here, the output signal of the front first detector 121 is an Ich (I channel) signal, and the output signal of the rear second detector 122 is a Qch (Q channel) signal. Incidentally, I of the Ich signal is an abbreviation for In-phase (in-phase), and Q of Qch is an abbreviation for Quadrature-phase (quadrature phase).

  A moving object pattern of a person (detected object) can be identified by the two channel signals of the Ich signal and the Qch signal. FIG. 11A shows waveform diagrams of the Ich signal and the Qch signal by the approaching person HA moving in the direction approaching the automatic door, and FIG. 11B shows the Ich signal by the leaving person HB moving in the direction away from the automatic door. Each waveform diagram of the Qch signal is shown.

  According to this, on the basis of the time when the Ich signal turns in the positive direction at the zero cross point, the time difference (phase difference) when the Qch signal similarly turns in the positive direction at the zero cross point is measured, and the time difference is 180 °. When the angle is smaller than 180 °, it can be determined that the person is an approaching person HA, and when it is larger than 180 °, the person is a leaving person HB.

  Alternatively, in the case of the approaching person HA, the direction at the zero crossing point of the Qch signal that appears first after the Ich signal turns to the positive direction at the zero crossing point is the positive direction, whereas the leaving person HB In this case, the direction at the zero-cross point of the Qch signal that appears first after the Ich signal turns to the positive direction at the zero-cross point is the negative direction, and this also distinguishes the approaching person HA and the leaving person HB. Can do.

  In any case, when detecting the approaching person HA, the control unit 14 outputs a door opening signal to the drive system of the automatic door 1 (see FIG. 12), and does not output the door opening signal in the case of the leaving person HB. . In an automatic door sensor using a radar, the door closing control is usually controlled in consideration of the output of a presence sensor such as a separate timer or a safety beam.

  As described above, according to the automatic door sensor using the radar, the approaching person HA and the leaving person HB can be identified by the moving body pattern.

  However, as shown in FIG. 12, when the approaching person HA and the leaving person HB exist within the monitoring area of the automatic door 1, particularly when the leaving person HB is near the automatic door 1 and the approaching person HA is far away. However, there is a problem that the signal level of the reflected wave is higher in the nearby leaving person HB, so that it does not react to the approaching person HA in the distance.

  Therefore, an object of the present invention is to be able to reliably identify only an approaching person when there are an approaching person moving in a direction approaching the automatic door and a leaving person moving in a direction away from the automatic door in the monitoring area of the automatic door. Is to make it.

  In order to solve the above-mentioned problem, an object detection method for an automatic door sensor using a radar according to the present invention provides a predetermined frequency as a transmitter / receiver for a monitoring area set in the vicinity of an automatic door as described in claim 1. An oscillating unit for transmitting a microwave and a receiving unit for receiving a reflected wave from an object existing in the monitoring region, wherein the first and second detectors have a wavelength of the microwave in the receiving unit. A radar is used that is spaced apart by λ / 4 in the front-rear direction as λ, and is based on the Ich signal output from the first detector ahead and the Qch signal output from the second detector behind. In an object detection method of an automatic door sensor using a radar that detects an object in the monitoring area and outputs an open / close control signal to the automatic door, any of the Ich signal and the Qch signal is detected by a phase shifter. One phase is shifted by + 90 ° or −90 ° with respect to the other, and then the Ich signal and the Qch signal are added or subtracted.

  In the automatic door sensor object detection method using the radar according to claim 1, when the phase of the Ich signal is shifted by + 90 ° with respect to the Qch signal as described in claim 2, a phase shift is performed. When the subsequent Ich signal and the Qch signal are subtracted and the phase of the Ich signal is shifted by −90 ° with respect to the Qch signal, the Ich signal after the phase shift and the Qch signal are added.

  An automatic door sensor using a radar according to the present invention includes an oscillating unit for transmitting a microwave of a predetermined frequency as a transmitter / receiver for a monitoring area set in the vicinity of the automatic door, as described in claim 3. A receiving unit that receives a reflected wave from an object existing in the monitoring region, and the first and second detectors are separated by λ / 4 in the front-rear direction, where the wavelength of the microwave is λ. Are used to detect an object in the monitoring area from the Ich signal output from the first detector ahead and the Qch signal output from the second detector behind. In an automatic door sensor using a radar that outputs an open / close control signal to the automatic door, the phase of one of the Ich signal and the Qch signal is shifted by + 90 ° or −90 ° with respect to the other. A phase shift means, a calculation means for adding or subtracting the Ich signal and the Qch signal after the phase shift by the phase shift means, and a direction approaching the automatic door based on a calculation value of the calculation means. And a judging means for detecting a reflected wave by a moving approaching object or a moving away object.

  The automatic door sensor using the radar according to claim 3, further comprising an A / D converter for converting the Ich signal and the Qch signal into digital signals, respectively, as described in claim 4, Even with digital signal processing software using a Hilbert transformer as the phase shift means, it is possible to realize identification of an approaching object moving in a direction approaching or moving away from the automatic door.

  An automatic door sensor using a radar according to the present invention includes an oscillating unit for transmitting a microwave of a predetermined frequency as a transmitter / receiver for a monitoring area set in the vicinity of the automatic door, as described in claim 5. A receiving unit that receives a reflected wave from an object existing in the monitoring area, and the first and second detectors in the receiving unit correspond to λ / 4 in the front-rear direction, where the wavelength of the microwave is λ. Radars that are spaced apart are used, and an object in the monitoring area is detected by the Ich signal output from the first detector at the front and the Qch signal output from the second detector at the rear. Then, in an automatic door sensor using a radar that outputs an open / close control signal to the automatic door, the phase of one of the Ich signal and the Qch signal is + 90 ° or −90 ° with respect to the other. Phase shifting means for shifting, a local oscillator that oscillates at a frequency substantially equal to or less than the maximum frequency of the reflected wave (Doppler frequency), and the Ich signal and the Qch signal after the phase shifting by the phase shifting means are the local oscillator. A frequency conversion means for performing orthogonal modulation at an output frequency of the output frequency, an approaching object that moves in a direction approaching the automatic door, or a direction away from the Ich signal and the Qch signal frequency-converted by the frequency conversion means. And a filter for detecting a reflected wave by a moving away object.

  An automatic door sensor using a radar according to the present invention includes an oscillating unit for transmitting a microwave of a predetermined frequency as a transmitter / receiver for a monitoring area set in the vicinity of an automatic door, as described in claim 6. A receiving unit that receives a reflected wave from an object existing in the monitoring area, and the first and second detectors in the receiving unit correspond to λ / 4 in the front-rear direction, where the wavelength of the microwave is λ. Radars that are spaced apart are used, and an object in the monitoring area is detected by the Ich signal output from the first detector at the front and the Qch signal output from the second detector at the rear. In an automatic door sensor using a radar that outputs an open / close control signal to the automatic door, an A / D converter that converts the Ich signal and the Qch signal into digital signals, respectively, and after the A / D conversion And the complex signal converting means for converting the Ich signal and the Qch signal into complex signals of the real part and the imaginary part, respectively, and reversing the sign of the imaginary part, and substantially the maximum frequency of the reflected wave (Doppler frequency) or lower. A complex local oscillator for generating a corresponding frequency; frequency converting means for orthogonally converting the complex signal at an output frequency of the complex local oscillator; and the complex signal converted by the frequency converting means to the automatic door. A digital filter that separates and detects reflected waves from an approaching object that moves in a direction approaching or a leaving object that moves away from the object is provided.

  An automatic door sensor using a radar according to the present invention includes an oscillating unit for transmitting a microwave of a predetermined frequency as a transmitter / receiver for a monitoring area set in the vicinity of the automatic door, as described in claim 7. A receiving unit that receives a reflected wave from an object existing in the monitoring area, and the first and second detectors in the receiving unit correspond to λ / 4 in the front-rear direction, where the wavelength of the microwave is λ. Radars that are spaced apart are used, and an object in the monitoring area is detected by the Ich signal output from the first detector at the front and the Qch signal output from the second detector at the rear. In an automatic door sensor using a radar that outputs an open / close control signal to the automatic door, an A / D converter that converts the Ich signal and the Qch signal into digital signals, respectively, and after the A / D conversion The Ich signal and the Qch signal as real and imaginary complex signals, which are subjected to Fourier transform or DCT transform (discrete cosine transform) to obtain a frequency spectrum of the complex signal; And an identification means for identifying an object moving in a direction toward or away from the automatic door by extracting and separating a positive or negative frequency from the automatic door.

  When both an approaching person and a leaving person exist in the monitoring area of the automatic door, the reflected wave (Doppler frequency) received by the radar includes a reflected wave by the approaching person and a reflected wave by the leaving person. Further, each reflected wave includes an Ich signal and a Qch signal that are 90 ° out of phase. Therefore, when the Ich signal is converted into a complex signal using the real part and the Qch signal as an imaginary part, the reflected wave received by the radar includes the real part Ia and the imaginary part Qa of the approaching person, and the real part Ib and the imaginary part of the leaving person. Qb is included. The real part Ia of the approaching person and the real part Ib of the leaving person are in phase, but the imaginary part Qa of the approaching person and the imaginary part Qb of the leaving person are inversion waveforms whose phases are different by 180 ° (see FIG. ) (B)).

  For example, if the phase of the real part Ia of the approaching person and the phase of the real part Ib of the leaving person are shifted by + 90 ° with respect to the imaginary part Qa of the approaching person and the imaginary part Qb of the leaving person, respectively, The imaginary part Qa of Ia and the approaching person has an inverted waveform with a phase difference of 180 °, and the real part Ib of the leaving person and the imaginary part Qb of the leaving person are in phase.

  Accordingly, by subtracting the real part Ia of the approaching person and the imaginary part Qa of the approaching person, and subtracting the real part Ib of the leaving person and the imaginary part Qb of the leaving person, the level of the reflected wave of the leaving person is almost It becomes 0, and only the reflected wave of the approaching person is left. On the other hand, if the sum is added, the reflected wave level of the approaching person becomes almost 0, and only the reflected wave on the leaving person side is detected.

  If the phase of the real part Ia of the approaching person and the phase of the real part Ib of the leaving person are shifted in a direction that is delayed by −90 ° with respect to the imaginary part Qa of the approaching person and the imaginary part Qb of the leaving person, respectively. Since the part Ia and the imaginary part Qa of the approaching person are in phase, and the real part Ib of the leaving person and the imaginary part Qb of the leaving person have an inverted waveform that is 180 degrees out of phase, the approaching part Ia and the approaching person's imaginary part Qb The part Qa may be added, and the real part Ib of the leaver and the imaginary part Qb of the leaver may be added. On the contrary, if the subtraction is performed, only the reflected wave on the side of the leaver is detected.

  For this reason, according to the invention described in claims 1 to 4, there are both an approaching person and a leaving person in the monitoring area of the automatic door, and the leaving person is near the automatic door. Even in the distance, it is possible to reliably detect a reflected wave by an approaching person who needs to open the door.

  According to the fifth and sixth aspects of the invention, the phase of either the Ich signal or the Qch signal is shifted by + 90 ° or −90 ° with respect to the other, and the Ich signal and the Qch signal are Since the quadrature modulation is performed by the local oscillator, the subsequent processing can be simplified. That is, it is possible to reliably extract only the reflected wave of either the approaching person or the leaving person with a normal filter.

  According to the seventh aspect of the present invention, after the Ich signal and the Qch signal are A / D converted, the complex signal converting means converts the Ich signal into a real signal and the Qch signal as an imaginary signal. , By obtaining a frequency spectrum of a complex signal by Fourier transform or DCT transform and extracting a positive frequency from the frequency spectrum, the main part is a simple configuration having a Fourier transform means, Only an approaching object that moves in a direction approaching the automatic door can be reliably identified. Similarly, if a negative frequency component is extracted, it is possible to separate and identify only the side of the leaver.

  Next, several embodiments of the present invention will be described with reference to FIGS. In this embodiment, it is assumed that an object approaching the automatic door is exclusively detected, but the present invention is not limited to this.

  First, a first embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, also in the automatic door sensor 10A according to the first embodiment, as described with reference to FIG. 10, the wavelength of the microwave transmitted from the dielectric oscillator 110 is λ, and the front and rear in the waveguide. A first detector 121 in front and a second detector in the rear are spaced apart by λ / 4 in the direction (λ / 4 + λ / 2n (n is an arbitrary positive integer; 0, 1, 2,...)). And a radar 11 (micro is a transceiver) 11 is used.

  Therefore, the radar 11 outputs an Ich signal and a Qch signal whose phase is shifted by 90 ° from the Ich signal in the delay direction. The automatic door sensor 10A according to the first embodiment receives the radar 11 signal. The phase shifter 21 that shifts the phase of either the Ich signal or the Qch signal output from the unit by 90 ° with respect to the other, and the Ich signal after the phase shift by the phase shifter 21 and the Qch signal are added or An adder / subtractor 22 that subtracts, a level detector 23 that detects an output level of the adder / subtractor 22, and a determiner 24 that determines whether the door is open based on the output of the level detector 23. A comparator or the like may be used for the level detector 23, and a microcomputer or the like may be used for the determiner 24.

  As described above with reference to FIG. 12, when there are an approaching person HA moving in the direction approaching the automatic door 1 and a leaving person HB moving in the direction away from the automatic door 1 in the monitoring area of the automatic door 1, The reflected wave (Doppler frequency) received by the radar 11 includes a reflected wave from the approaching person HA and a reflected wave from the leaving person HB.

  Furthermore, an Ich signal and a Qch signal having a phase difference of 90 ° are obtained from each reflected wave in the receiver. Therefore, when the Ich signal is converted into a complex signal with the real part and the Qch signal as an imaginary part, the reflected wave received by the radar 11 includes the real part Ia of the approaching person HA shown in FIG. The imaginary part Qa of the approaching person HA shown in FIG. 3A, the real part Ib of the leaving person HB shown in FIG. 3A and the imaginary part Qb of the leaving person HB shown in FIG.

  The real part Ia of the approaching person HA and the real part Ib of the leaving person HB are in phase, but the imaginary part Qa of the approaching person HA and the imaginary part Qb of the leaving person HB have inverted waveforms whose phases are different by 180 °. Using this phenomenon, only the approaching person HA is detected in the first embodiment. Therefore, in this example, the phase shifter 21 shifts the phase of the Ich signal in the direction of + 90 ° with respect to the Qch signal, and the adder / subtractor 22 is used as a subtractor.

  The approaching person HA will be described. The real part Ia of the approaching person HA shown in FIG. 2A is shifted in the direction in which the phase advances by + 90 ° as shown in FIG. Since the degree of phase shift with respect to the signal is 0 °, the imaginary part Qa of the approaching person HA passes through the phase shifter 21 with the waveform shown in FIG.

  Therefore, as can be seen by comparing FIG. 2 (b) and FIG. 2 (c), the real part Ia of the approaching person HA and the imaginary part Qa of the approaching person HA after the phase shift have inverted waveforms that are 180 ° different in phase. Therefore, by subtracting the real part Ia and the imaginary part Qa by the adder / subtractor 22, as shown in FIG. 2 (d), the level is approximately twice the level of the real part Ia and the imaginary part Qa. A composite waveform is obtained.

  Similarly, the real part Ib of the leaver HB shown in FIG. 3A is shifted in the direction in which the phase advances by + 90 ° as shown in FIG. 3C by the phase shifter 21, while the phase shift for the Qch signal is performed. Since the degree is 0 °, the imaginary part Qb of the leaver HB passes through the phase shifter 21 with the waveform shown in FIG.

  Therefore, as can be seen by comparing FIG. 3B and FIG. 3C, the real part Ib of the leaver HB after the phase shift and the imaginary part Qb of the leaver HB are in phase, so this real part By subtracting the Ib and the imaginary part Qb by the adder / subtractor 22, the level becomes almost zero as shown in FIG.

  As described above, the phase shift degree of the Qch signal is set to 0 and the phase of the Ich signal is shifted in the direction of + 90 °, and then the subtracted Ich signal and Qch signal cancel the reflected wave from the leaver HB. When only the reflected wave from the approaching person HA is taken out and the level is equal to or higher than a predetermined threshold value, the output of the level detector 23 changes from Lo to Hi, for example.

  Upon receiving the Hi output of the level detector 23, the determiner 24 determines that the approaching person HA is in the vicinity of the automatic door 1 and outputs a door open signal. In addition, when the level of the reflected wave by approaching person HA is less than the said threshold value, it determines with the position of approaching person HA being too far from an automatic door, and a door open signal is not output.

  In the above example, the phase of the Ich signal is shifted in the direction of + 90 °, but may be shifted in the direction of −90 °. In this case, the real part Ia of the approaching person HA and the approaching person after the phase shift. The imaginary part Qa of the HA has the same phase. On the other hand, the real part Ib of the leaving person HB after the phase shift and the imaginary part Qb of the leaving person HB have inverted waveforms whose phases are different by 180 °. It can be operated as a container.

  Further, the phase shift degree of the Ich signal may be set to 0, and the phase of the Qch signal may be shifted by + 90 ° or −90 °. In addition, what is necessary is just to reverse said addition / subtraction, when not identifying the approaching person HA side but identifying the leaving person HB side.

  Next, a second embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 12, when there are an approaching person HA moving in the direction approaching the automatic door 1 and a leaving person HB moving in the direction away from the automatic door 1 in the monitoring area of the automatic door 1, The reflected wave (Doppler frequency) received by the radar 11 includes a reflected wave from the approaching person HA and a reflected wave from the leaving person HB, and the Doppler frequency of these reflected waves is well known. Depends on the moving speed of the approaching person HA and the leaving person HB.

Here, the relationship between the movement speed of the person with respect to the radar 11 and the Doppler frequency will be described. The wavelength of the microwave transmitted from the radar 11 is λ, the movement speed of the person is V, and the incident angle of the reflected wave with respect to the radar 11 is θ. When the Doppler frequency f _D is calculated by the following equation.
f _D = (2 × V × cos θ) / λ

Therefore, for example, when the frequency of the microwave transmitted from the radar 11 is 24 GHz (λ = 0.0125 m), the incident angle θ = 0, and the walking speed of the person is 0.06 to 3 m / s, the Doppler frequency f _D is about 10 to 100 Hz.

  By the way, if the moving speeds of the approaching person HA and the leaving person HB are the same, those reflected waves have the same frequency. However, when viewed as a complex signal, the frequency is the vector diagram of FIG. As shown in the spectrum of b), the positive and negative polarities are different. In FIG. 4A, + ω is the approaching direction and −ω is the leaving direction.

  In order to discriminate the sign of the Doppler frequency between the approaching person HA and the leaving person HB, in the second embodiment, each received signal of the approaching person HA and the leaving person HB is subjected to frequency conversion by single-sideband modulation. That is, in the automatic door sensor 10B according to the second embodiment shown in FIG. 5, the Doppler frequency by the approaching person HA and the leaving person HB is moved over the entire spectrum as shown in (a) to (d) of FIG. The moving speed of the target approaching person HA is separated by a filter.

  Specifically, when the Doppler frequency components of the Ich signal and the Qch signal output from the receiving unit of the radar 11 are about 10 to 500 Hz as described above, the complex signal of the Ich signal and the Qch signal is as shown in FIG. As shown in the spectrum, the approaching person HA side has a positive frequency (+10 to +500 Hz), and the leaving person HB side has a negative frequency (−500 to −10 Hz).

  The phase of the Qch signal is shifted by -180 ° phase shifter 31 in the -180 ° delay direction so that the approaching person HA side has a negative frequency and the leaving person HB side has a positive frequency. Thereby, as shown in the spectrum of FIG. 5 (a), the approaching person HA side becomes −500 to −10 Hz, and the leaving person HB side becomes +10 to +500 Hz.

  Separately, the local oscillator 32 creates a frequency corresponding to the highest signal frequency of the Doppler frequency (in this case, 500 Hz), and the Ich signal is frequency-converted by the mixer 33 at the local oscillation frequency. To do.

  On the other hand, for the Qch signal, a complex -90 ° component in which the phase of the local oscillation frequency of the local oscillator 32 is shifted by a -90 ° phase shifter in the -90 ° delay direction is created, and the complex 35 is generated by the mixer 35. The Qch signal is quadrature-modulated by a 90 ° component.

  Then, the Ich signal frequency-converted by the mixer 33 and the Qch signal orthogonally modulated by the mixer 35 are added by the adder 36, and the approaching HA side is 0 as shown in the spectrum of FIG. Frequency conversion is performed so that the side of the vacant HB is 510 Hz to 1 kHz.

  Then, by selecting a frequency of, for example, 490 Hz or less with the low-pass filter 37, only the Doppler frequency by the approaching person HA can be obtained. When the level is equal to or higher than a predetermined threshold, the output of the level detector (comparator) 38 From Lo to Hi, for example, the determination unit 39 determines that the approaching person HA is in the vicinity of the automatic door 1 and outputs a door open signal.

  In the above example, after the phase on the Qch signal side is shifted by -180 ° by the -180 ° phase shifter 31, the output of the local oscillator 32 is shifted by -90 ° by the -90 ° phase shifter. Later, quadrature modulation is performed, but the phase on the Qch signal side is left as it is, and the output of the local oscillator 32 is quadrature modulated on the Ich signal side with a signal shifted by -90 ° or + 90 °, and the entire spectrum is on the positive side. Alternatively, it may be moved to the negative side, and only the spectrum of the approaching person HA may be selected by using a filter. Further, the frequency of the local oscillator 32 can be set to 250 Hz, and the approaching person frequency shown in FIG. 5D can be set to -250 to +250 Hz.

  Next, a third embodiment of the present invention will be described with reference to FIG. 6a. The Doppler frequencies of the approaching person HA and the leaving person HB are complexly converted, the whole spectrum is moved to the positive side or the negative side, and only the Doppler frequency of the approaching person HA is extracted by a filter. In the third embodiment, the processing is performed digitally.

  Therefore, in the automatic door sensor 10C according to the third embodiment shown in FIG. 6A, first, each of the Ich signal and the Qch signal output from the receiving unit of the radar 11 is converted into a digital signal by the A / D converter 41.

  If the Doppler frequency of the Ich signal and Qch signal output from the receiving unit of the radar 11 is about 10 to 500 Hz as in the second embodiment, the complex signal of the Ich signal and the Qch signal is shown in FIG. As shown, the approaching person HA side has a positive frequency and the leaving person HB side has a negative frequency.

  In this example, the maximum frequency after frequency conversion, which will be described later, is 1 kHz, which is twice the Doppler frequency of the Ich signal and the Qch signal, as shown in the spectrum of FIG. The conversion is further doubled by Shannon's sampling theorem (sampling at twice the frequency of the signal band), and sampling is performed at 2 kHz, which is four times the signal band.

  Next, in order to exchange the positive and negative frequencies of the Ich signal and the Qch signal after A / D conversion, the complex signal converting means 42 inverts the Qch signal side to make a complex signal as Sn = I−jQ and approaches it. The Doppler frequency on the HA side is switched to the negative frequency band. As a result, as shown in the spectrum of FIG. 6A (A), the approaching side is −500 to −10 Hz, and the leaving side is 10 to 500 Hz.

  Next, the entire spectrum shown in FIG. 6A (A) is moved to the positive frequency band by the frequency converting means 43. Therefore, the frequency conversion means 43 includes functions of a complex local oscillator 431 and a mixer (multiplier) 432 constructed by software.

  The complex local oscillator 431 generates a frequency corresponding to the highest signal frequency (in this example, +500 Hz). In this case, a complex OSC signal (cos ωt + jsin ωt) having a sampling frequency of 2 kHz and a frequency of +500 Hz is generated, and these values are repetitions of (1 + j0) → (0 + j) → (−1 + j0) → (0−j). Therefore, a complex OSC signal can be easily created.

  For the orthogonal transform, a complex product of the complex signal generated by the complex signal converting means 42 and the complex OSC signal is obtained by a mixer (multiplier) 432, as shown in the spectrum of FIG. In addition, it is possible to obtain a signal whose frequency is converted to 0 to 490 Hz on the approach side and 510 to 1 kHz on the separation side.

  Thereafter, as in the first and second embodiments, by selecting a frequency of, for example, 490 Hz or less by the filter function 44, only the Doppler frequency by the approaching person HA can be obtained, and the level is equal to or higher than a predetermined threshold value. In this case, the output of the level detector (comparator) 45 changes from Lo to Hi, for example, and in response to this, the determiner 46 determines that the approaching person HA is in the vicinity of the automatic door 1 and outputs a door open signal.

  In the above example, the Qch signal side is inverted between positive and negative to convert it into a complex signal as Sn = I−jQ, and frequency conversion is performed. However, as a first modification of the third embodiment, FIG. 6b (a) remains the same (same as the spectrum of FIG. 6a (a)), that is, without changing the frequency on the approaching side and the leaving side, it is converted into a complex signal as Sn = I + jQ and shown in FIG. 6b (a). Instead of obtaining a spectrum after conversion to a complex signal, orthogonal transform may be performed with the frequency of the complex OSC signal set to -500 Hz.

  According to this, as shown in FIG. 6B (c), the entire spectrum is shifted to a negative frequency band, the separation side is −1 kHz to 510 Hz, and the approaching side is −490 to 0 Hz. Thus, by extracting the frequency band of −490 to 0 Hz with the filter 44, only the approaching person HA can be detected.

  In the first modified example, orthogonal transformation is performed with the frequency of the complex OSC signal set to −500 Hz. However, as a second modified example of the third embodiment, orthogonal transformation may be performed with the frequency of the complex OSC signal set to +500 Hz.

  That is, the spectrum shown in FIG. 6c (a) (same as the spectrum of FIG. 6a (a)), that is, without changing the frequencies on the approaching side and the leaving side, is converted into a complex signal as Sn = I + jQ. In the second modified example, the complex OSC signal frequency is +500 Hz and orthogonally transformed.

  According to this, as shown in FIG. 6c (c), the entire spectrum is shifted from the state of FIG. 6c (a) to the positive frequency band, the separation side is 0 to 490 Hz, and the approaching side is 510 Hz to 1 kHz. As shown in 6c (d), by extracting the frequency band of 510 Hz to 1 kHz by the filter 44, only the approaching person HA can be detected.

  Further, as a third modification of the third embodiment, as shown in FIG. 6D (A), the frequency of the complex OSC signal may be orthogonally converted to -250 Hz located substantially in the middle of the close-side frequency band.

  That is, while maintaining the spectrum shown in FIG. 6d (a) (same as the spectrum of FIG. 6a (a)) without changing the frequencies on the approaching side and the leaving side, a complex signal is formed as Sn = I + jQ, and FIG. In the third modified example, the complex OSC signal frequency is -250 Hz and orthogonally transformed.

  According to this, as shown in FIG. 6d (c), the separation side is −750 to −260 Hz, and the approaching side is −240 Hz to +250 Hz. Therefore, as shown in FIG. By extracting the frequency band of 250 Hz, only the approaching person HA can be detected.

  Next, a fourth embodiment of the present invention will be described with reference to FIG. The fourth embodiment is based on the fact that when a complex signal is subjected to frequency analysis, it can be separated into a positive frequency and a negative frequency.

  Therefore, an automatic door sensor 10D according to the fourth embodiment shown in FIG. 7 has an A / D converter 51 that converts an Ich signal and a Qch signal output from the receiving unit of the radar 11 into digital signals, respectively, as a basic configuration. And a complex Fourier transform means 52 for Fourier transforming a complex signal in which the Ich signal after A / D conversion is a real part I and a Qch signal is an imaginary part jQ, and a close-side signal is detected from the frequency spectrum obtained by the Fourier transform And control means 53 for controlling the automatic door.

  FIG. 7A shows a spectrum of a complex signal in which the Ich signal after A / D conversion is a real part I and the Qch signal is an imaginary part jQ. In the spectrum of this complex signal, the separation side is −500 to −10 Hz, and the approaching side is 10 to 500 Hz. When this is Fourier-transformed by the complex Fourier transform means 52, it is shown in the frequency spectrum of FIG. Thus, since the approaching side is aligned with the positive frequency and the leaving side is aligned with the negative frequency, the control means 53 extracts only the positive frequency portion from the frequency spectrum, and when the level is equal to or higher than the predetermined value, the door opening is performed. Output a signal. Note that DCT transform (discrete cosine transform) may be performed instead of Fourier transform.

  Next, a fifth embodiment of the present invention will be described with reference to FIG. In the fifth embodiment, the analog processing in the first embodiment is replaced with digital processing.

  That is, the automatic door sensor 10D according to the fifth embodiment includes an A / D converter 61 that converts an Ich signal and a Qch signal output from the receiving unit of the radar 11 into a digital signal, and any of the Ich signal and the Qch signal. The phase shift means 62 is provided as a phase shifter that shifts one of the phases by + 90 ° or −90 ° with respect to the other, and a Hilbert transformer is used as the phase shift means 62.

  The adder / subtractor 63, the level detector 64, and the determiner 65 connected to the subsequent stage of the phase shift means 62 have the same configuration as the adder / subtracter 22, the level detector 23, and the determiner 24 in the first embodiment. Good.

  Since the configuration of the Hilbert transformer is well known, the description thereof is omitted here. By using the Hilbert transformer, a signal whose phase is constantly changed by 90 ° is obtained even if the frequency is changed only by software calculation. It is possible to separate only the Doppler frequencies on the near side by adding them. This method has the advantage that only the addition / subtraction multiplication is required, and the calculation power required is small because complex multiplication is not used.

  In addition, as described above, according to the radar sensor of the present invention, not only an approaching person but also a leaving person can be identified. For example, it is desired to close an opened automatic door early in response to a request for reducing an air conditioning load. Even in this case, the radar sensor of the present invention can be applied. In that case, other sensors can be used in combination.

The schematic diagram which shows the structure of the automatic door sensor by 1st Embodiment of this invention. (A)-(d) The wave form diagram which shows the signal processing procedure by the side of an approacher in the said 1st Embodiment. (A)-(d) The wave form diagram which shows the signal processing procedure by the left side in the said 1st Embodiment. (A) A vector diagram showing each reflected wave of the approaching person and the leaving person, (b) A schematic diagram showing a frequency spectrum of each reflected wave of the approaching person and the leaving person. The schematic diagram which shows the structure of the automatic door sensor by 2nd Embodiment of this invention, and the transition of the frequency spectrum accompanying the signal processing. The schematic diagram which shows the structure of the automatic door sensor by 3rd Embodiment of this invention, and the transition of the frequency spectrum accompanying the signal processing. The schematic diagram which shows the transition of the frequency spectrum accompanying the signal processing of the 1st modification of the said 3rd Embodiment. The schematic diagram which shows the transition of the frequency spectrum accompanying the signal processing of the 2nd modification of the said 3rd Embodiment. The schematic diagram which shows the transition of the frequency spectrum accompanying the signal processing of the 3rd modification of the said 3rd Embodiment. The schematic diagram which shows the structure of the automatic door sensor by 4th Embodiment of this invention, and the transition of the frequency spectrum accompanying the signal processing. The schematic diagram which shows the structure of the automatic door sensor by 5th Embodiment of this invention. The schematic diagram which shows the structure of the automatic door sensor as a prior art example. The schematic diagram which shows the structure of the radar applied to an automatic door sensor. The wave form diagram which shows the phase relationship of each Ich signal and Qch signal of the approaching person and leaving person output from the receiving part of the said radar. The schematic diagram which shows the monitoring area | region set to the automatic door vicinity.

Explanation of symbols

10A to 10E Automatic door sensor 11 Radar 121 Front first detector that outputs Ich signal 122 Rear second detector that outputs Qch signal 21 Phase shifter 22 Adder / subtractor 23, 38, 45 Level detector 24, 39, 46 Determinator 31 -180 ° phase shifter 32 Local oscillator 33, 35, 432 Mixer (multiplier)
34-90 ° phase shifter 37 Low-pass filter 41, 51 A / D converter 42 Complex signal converting means 43 Frequency converting means 431 Complex local oscillator 44 Filter 52 Complex Fourier transform means 62 Phase shifter (Hilbert transformer)

Claims (7)

As a transmitter / receiver for a monitoring region set in the vicinity of an automatic door, the receiving unit includes an oscillating unit that transmits a microwave having a predetermined frequency and a receiving unit that receives a reflected wave from an object existing in the monitoring region. A radar is used in which the first and second detectors are arranged with the wavelength of the microwave set to be λ / 4 and spaced apart by λ / 4 in the front-rear direction, and the Ich output from the front first detector In an object detection method for an automatic door sensor using a radar that detects an object in the monitoring region and outputs an open / close control signal to the automatic door by using a signal and a Qch signal output from the second detector behind.
A phase shifter shifts the phase of either the Ich signal or the Qch signal by + 90 ° or −90 ° with respect to the other, and then adds or subtracts the Ich signal and the Qch signal. An object detection method of an automatic door sensor using a radar.   When the phase of the Ich signal is shifted by + 90 ° with respect to the Qch signal, the phase-shifted Ich signal and the Qch signal are subtracted, and the phase of the Ich signal is shifted by −90 ° with respect to the Qch signal. 2. The object detection method for an automatic door sensor using a radar according to claim 1, wherein the Ich signal after the phase shift and the Qch signal are added. 3. As a transmitter / receiver for a monitoring region set in the vicinity of an automatic door, the receiving unit includes an oscillating unit that transmits a microwave having a predetermined frequency and a receiving unit that receives a reflected wave from an object existing in the monitoring region. A radar is used in which the first and second detectors are arranged with the wavelength of the microwave set to be λ / 4 and spaced apart by λ / 4 in the front-rear direction, and the Ich output from the front first detector In an automatic door sensor using a radar that detects an object in the monitoring region and outputs an open / close control signal to the automatic door by a signal and a Qch signal output from the second detector behind,
Phase shifting means for shifting either the Ich signal or the Qch signal by + 90 ° or −90 ° with respect to the other, the Ich signal after the phase shifting by the phase shifting means, and the Qch signal A calculating means for adding or subtracting; and a determining means for separating and detecting a reflected wave from an approaching object moving in a direction approaching the automatic door or a moving away object moving away from the automatic door based on a calculation value of the calculation means; An automatic door sensor using a radar characterized by comprising:   4. An A / D converter for converting the Ich signal and the Qch signal into digital signals, respectively, and performing digital processing by software using a Hilbert converter as the phase shift means. Automatic door sensor using the radar described in 1. As a transmitter / receiver for a monitoring region set in the vicinity of an automatic door, the receiving unit includes an oscillating unit that transmits a microwave having a predetermined frequency and a receiving unit that receives a reflected wave from an object existing in the monitoring region. A radar is used in which the first and second detectors are arranged with the wavelength of the microwave set to be λ / 4 and spaced apart by λ / 4 in the front-rear direction, and the Ich output from the front first detector In an automatic door sensor using a radar that detects an object in the monitoring region and outputs an open / close control signal to the automatic door by a signal and a Qch signal output from the second detector behind,
Phase shifting means for shifting the phase of one of the Ich signal and the Qch signal by + 90 ° or −90 ° with respect to the other, and a frequency corresponding to substantially the maximum frequency or less of the reflected wave (Doppler frequency) A local oscillator that oscillates the frequency, a frequency conversion means that quadrature modulates the Ich signal and the Qch signal after the phase shift by the phase shift means at the output frequency of the local oscillator, and the frequency converter that is converted by the frequency converter And a filter that separates and detects a reflected wave from an approaching object that moves in the direction approaching the automatic door or a leaving object that moves away from the Ich signal and the Qch signal. Automatic door sensor using radar. As a transmitter / receiver for a monitoring region set in the vicinity of an automatic door, the receiving unit includes an oscillating unit that transmits a microwave having a predetermined frequency and a receiving unit that receives a reflected wave from an object existing in the monitoring region. A radar is used in which the first and second detectors are arranged with the wavelength of the microwave set to be λ / 4 and spaced apart by λ / 4 in the front-rear direction, and the Ich output from the front first detector In an automatic door sensor using a radar that detects an object in the monitoring region and outputs an open / close control signal to the automatic door by a signal and a Qch signal output from the second detector behind,
An A / D converter that converts each of the Ich signal and the Qch signal into a digital signal, and after the A / D conversion, the Ich signal and the Qch signal are converted into complex signals of a real part and an imaginary part, respectively, and the imaginary part Complex signal generating means for inverting the sign of the part, a complex local oscillator that generates a frequency corresponding to substantially the maximum frequency of the reflected wave (Doppler frequency) or less, and the complex signal as an output frequency of the complex local oscillator The reflected wave from the frequency conversion means for orthogonal transformation and the approaching object moving in the direction approaching or moving away from the automatic door is separated from the complex signal converted by the frequency conversion means. An automatic door sensor using a radar, characterized by comprising a digital filter for detection. As a transmitter / receiver for a monitoring region set in the vicinity of an automatic door, the receiving unit includes an oscillating unit that transmits a microwave having a predetermined frequency and a receiving unit that receives a reflected wave from an object existing in the monitoring region. A radar is used in which the first and second detectors are arranged with the wavelength of the microwave set to be λ / 4 and spaced apart by λ / 4 in the front-rear direction, and the Ich output from the front first detector In an automatic door sensor using a radar that detects an object in the monitoring region and outputs an open / close control signal to the automatic door by a signal and a Qch signal output from the second detector behind,
An A / D converter that converts each of the Ich signal and the Qch signal into a digital signal, and after the A / D conversion, the Ich signal and the Qch signal are converted into complex signals of a real part and an imaginary part, and this is subjected to Fourier transform Alternatively, conversion means for obtaining the frequency spectrum of the complex signal by DCT conversion (discrete cosine transform), and a direction in which a positive or negative frequency is extracted from the frequency spectrum and separated to approach or move away from the automatic door. An automatic door sensor using a radar, comprising: an identification means for identifying an object that moves.

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