JP2020165784A - Target detector, system, program, and method - Google Patents

Abstract

To distinguish a moving target from a stationary target in detecting the moving target, and reduce a calculation load, a storage load, and a consumption load.SOLUTION: A target detector 1 includes: a beat signal acquisition unit 11 for acquiring a beat signal between sending-receiving signals of an FMCW radar; a differential signal calculation unit 12 for calculating a differential signal between beat signals with different sending-receiving cycles; and a moving target detection unit 13 for detecting the presence of a moving target in a detection distance range when the intensity of the differential signal is at least a predetermined signal intensity, and detecting the absence of a moving target in the detection distance range when the intensity of the differential signal is lower than the predetermined signal intensity.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a technique for detecting a moving object using an FMCW radar.

A technique for detecting a target using an FMCW radar is disclosed in Patent Document 1 and the like. The lower / higher the frequency of the beat signal between the frequency-swept transmission signal and the reception signal reflected from the target, the shorter / longer the target distance is measured.

JP-A-11-271429

In Patent Document 1, in order to detect a moving target, beat signals are frequency-converted in different transmission / reception cycles, and the spectrum of the target distance is compared. However, when a moving target is present and a stationary target is also present, it is difficult to distinguish the moving target from the stationary target because the stationary target is superimposed on the moving target in the spectrum of the target distance. Is. Further, even when there is no moving target but only a stationary target, it is difficult to reduce the calculation load, the storage capacity, and the power consumption because the beat signal is frequency-converted in each transmission / reception cycle. ..

Therefore, in order to solve the above-mentioned problems, it is an object of the present disclosure to distinguish a moving object from a stationary object and reduce a calculation load, a storage capacity and a power consumption in detecting a moving object.

In order to solve the above problem, it was decided to calculate the difference signal between the beat signals of different transmission / reception cycles and detect the presence / absence of the moving object target based on the strength of the difference signal. It is not necessary to dare to frequency-convert beat signals having different transmission / reception cycles and detect the presence / absence of a moving target based on the spectrum of the target distance. Here, for the moving object, the strength of the difference signal becomes a finite value because the beat signals of different transmission / reception cycles change with time. However, for the stationary object target, the strength of the difference signal becomes almost 0 because the beat signals of different transmission / reception cycles do not change with time.

Specifically, the present disclosure discloses a beat signal acquisition unit that acquires beat signals between transmission and reception signals of an FMCW radar, a difference signal calculation unit that calculates a difference signal between the beat signals having different transmission and reception cycles, and the difference signal. When the intensity of is equal to or greater than the predetermined signal intensity, it is detected that a moving object is present within the detection distance range, and when the intensity of the difference signal is lower than the predetermined signal intensity, the said is within the detection distance range. The target detection device is provided with a moving target detection unit for detecting the absence of a moving target.

Further, the present disclosure is a target detection system including the target detection device described above and the radar transmission / reception device of the FMCW radar.

Further, in the present disclosure, the beat signal acquisition step of acquiring the beat signal between the transmission / reception signals of the FMCW radar, the difference signal calculation step of calculating the difference signal between the beat signals of different transmission / reception cycles, and the strength of the difference signal are described. When the signal strength is equal to or higher than the predetermined signal strength, it is detected that a moving target is present within the detection distance range, and when the strength of the difference signal is lower than the predetermined signal strength, the moving target is within the detection distance range. This is a target detection program for causing a computer to execute a moving target detection step for detecting the absence of a signal.

Further, in the present disclosure, the beat signal acquisition step of acquiring the beat signal between the transmission / reception signals of the FMCW radar, the difference signal calculation step of calculating the difference signal between the beat signals of different transmission / reception cycles, and the strength of the difference signal are described. When the signal strength is equal to or higher than the predetermined signal strength, it is detected that a moving target is present within the detection distance range, and when the strength of the difference signal is lower than the predetermined signal strength, the moving target is within the detection distance range. This is a target detection method characterized in that a moving target detection step for detecting the absence of is provided in order.

According to these configurations, when detecting a moving object, the moving object can be distinguished from the stationary object, and the calculation load, the storage capacity, and the power consumption can be reduced.

Further, in the present disclosure, the moving object detection unit rotates without moving within the detection distance range when the beat frequencies are the same and the beat phases are different between the beat signals having different transmission / reception cycles. Alternatively, it is a target detection device characterized in that it detects the presence of a vibrating rotation / vibration target.

Even for a rotation / vibration target in which the target distance does not change, the strength of the difference signal becomes a finite value because the beat signals of different transmission / reception cycles change with time. Therefore, it is not possible to distinguish a rotating / vibrating target from a moving target based only on the strength of the difference signal. However, according to this configuration, the rotation / vibration target can be distinguished from the moving target based on the fact that the beat frequencies of different transmission / reception cycles are the same before the frequency conversion of the difference signal or the beat signal.

Further, in the present disclosure, when the moving object detection unit detects that the moving object exists within the detection distance range, the moving object target detects the difference signal or the beat signal by frequency conversion, and the moving object target. When the moving object target distance, which is the distance to the moving object, is measured and it is detected that the moving object target does not exist within the detection distance range, the frequency conversion of the difference signal or the beat signal is stopped, and the moving object is stopped. It is a target detection device characterized by stopping the measurement of the target distance.

According to this configuration, since the difference signal or the beat signal is frequency-converted only when a moving object is detected, the calculation load, the storage capacity, and the power consumption can be reduced.

Further, in the present disclosure, the moving object detection unit rotates or vibrates without moving within the detection distance range when the moving object target distances in the different transmission / reception cycles are the same. It is characterized in that it detects the existence of a target and detects the existence of the moving target moving within the detection distance range when the moving target distances in the different transmission / reception cycles are different. It is a target detection device.

Even for a rotation / vibration target in which the target distance does not change, the strength of the difference signal becomes a finite value because the beat signals of different transmission / reception cycles change with time. Therefore, it is not possible to distinguish a rotating / oscillating target from a moving target based solely on the strength of the difference signal. However, according to this configuration, after frequency conversion of the difference signal or the beat signal, the rotation / vibration target can be distinguished from the moving target based on the fact that the moving object distances of different transmission / reception cycles are the same. ..

Further, the present disclosure is characterized in that the moving object detection unit adjusts the sampling frequency and the modulation frequency for the difference signal or the beat signal, and adjusts the measurement resolution and the measurement range for the moving object distance. It is a target detection device.

According to this configuration, by setting the sampling frequency of the difference signal or the beat signal to a low frequency, the measurement resolution is improved at a short distance and a long distance without increasing the order of frequency conversion of the difference signal or the beat signal. Can be made to. Then, by setting the modulation frequency of the difference signal or beat signal to low frequency / high frequency, that is, by setting the lower limit of the measurement range to short distance / long distance, the order of frequency conversion of the difference signal or beat signal. The measurement resolution can be improved at a short distance / a long distance without increasing the frequency.

Further, in the present disclosure, the moving object target detection unit does not discard and output the moving object target distance that is not included in the predetermined distance range, but adopts the moving object target distance that is included in the predetermined distance range. It is a target detection device characterized by outputting.

According to this configuration, when only a short distance / long distance is to be detected, or when there is a noise source at a long distance / short distance, only the short distance / long distance can be adopted and output.

As described above, in the present disclosure, when detecting a moving object, the moving object can be distinguished from the stationary object, and the calculation load, the storage capacity and the power consumption can be reduced.

It is a figure which shows the structure of the object detection system of this disclosure. It is a figure which shows the procedure of the object detection processing of this disclosure. It is a figure which shows the specific example of the target detection process of this disclosure. It is a figure which shows the specific example of the target detection process of this disclosure. It is a figure which shows the specific example of the target detection process of this disclosure. It is a figure which shows the specific example of the target detection process of this disclosure. It is a figure which shows the structure of the moving object detection part of this disclosure. It is a figure which shows the output of the moving object reference distance of this disclosure.

Embodiments of the present disclosure will be described with reference to the accompanying drawings. The embodiments described below are examples of embodiments of the present disclosure, and the present disclosure is not limited to the following embodiments.

The configuration of the target detection system of the present disclosure is shown in FIG. The target detection system S includes a target detection device 1 and an FMCW radar transmission / reception device 2. The target detection device 1 is composed of a beat signal acquisition unit 11, a difference signal calculation unit 12, and a moving target detection unit 13, and is installed with the target detection program shown in FIG. The FMCW radar transmitter / receiver 2 includes a PLL circuit 21, an oscillator 22, a distributor 23, an amplifier 24, a low-pass filter 25, a transmitting antenna 26, a receiving antenna 27, an amplifier 28, an amplifier 29, a mixer circuit 30, a calibrator 31I, 31Q, A /. It is composed of a D converter 32 and a phase modulator 33.

The PLL circuit 21 controls the oscillator 22 by the control signal of the target detection device 1. The oscillator 22 generates a frequency-swept transmission signal based on the control signal of the PLL circuit 21. The distributor 23 distributes the frequency-swept transmission signal to the amplifier 24 and the amplifier 29. The amplifier 24 amplifies the frequency-swept transmission signal. The low-pass filter 25 passes only the necessary low-frequency components from the frequency-swept transmission signal and removes the unnecessary high-frequency components. The transmitting antenna 26 irradiates the frequency-swept transmission signal.

The receiving antenna 27 receives the reflected signal reflected from the target T. The amplifier 28 amplifies the reflected signal reflected from the target T. The amplifier 29 amplifies the frequency-swept transmission signal. The mixer circuit 30 outputs the I, Q components IF I, and IF Q of the beat signal between the frequency-swept transmission signal LO and the reflected signal RF reflected from the target T. The calibrators 31I and 31Q use the control signal DC CAL of the target detection device 1 to remove frequency components near DC from the I, Q components IF I and IF Q of the beat signal, and the I and Q components CAL I of the beat signal. Keep CAL Q within the dynamic range. The A / D converter 32 A / D-converts the I and Q components CAL I and CAL Q of the beat signal, and outputs the I and Q components A / D I and A / D Q of the beat signal. The phase modulator 33 modulates the phase of the frequency-swept transmission signal and the reflected signal reflected from the target T by the control signal DC CAL of the target detection device 1, and the I, Q component IF I, of the beat signal, The frequency component near the DC is removed from the IF Q, and the I, Q components CAL I, and CAL Q of the beat signal are kept within the dynamic range.

The procedure of the target detection process of the present disclosure is shown in FIG. Specific examples of the target detection process of the present disclosure are shown in FIGS. 3 to 6. The beat signal acquisition unit 11 acquires the I, Q components A / D I, and A / D Q of the beat signal between the transmission / reception signals of the FMCW radar (step S1).

The difference signal calculation unit 12 calculates the I, Q component A / D I of the beat signal of different transmission / reception cycles, and the I, Q component SUB I, and SUB Q of the difference signal between the A / D Q (step S2). Note that step S3 will be described later with reference to FIG. 7. Next, steps S4 to S11 will be described with reference to FIGS. 3 to 6.

In FIG. 3, when the intensities of the I, Q components SUB I, and SUB Q of the difference signal are equal to or higher than the predetermined signal intensities (YES in step S4), the moving object target detecting unit 13 is within the detection distance range. Is detected (step S5). Then, the moving object target detecting unit 13 executes frequency conversion of the difference signal I, Q component SUB I, SUB Q, or the beat signal I, Q component A / DI, A / D Q, and moves the moving object target distance. Is executed (step S6).

On the other hand, when the intensity of the I, Q components SUB I, and SUB Q of the difference signal is lower than the predetermined signal intensity (NO in step S4), the moving object target detecting unit 13 has a moving object indicator within the detection distance range. Detects that it does not (step S7). Then, the moving object target detection unit 13 stops the frequency conversion of the I, Q component SUB I, SUB Q of the difference signal or the I, Q component A / DI, A / D Q of the beat signal, and the moving object target distance. (Step S8). After step S8 is executed, steps S9 to S14 are not executed.

Specifically, the beat signal acquisition unit 11 acquires beat signals from reception start times t _R1 and t _R2 to transmission end times t _T1 and t _T2 for each of the first and second transmission / reception cycles. Here, with respect to the moving object, the beat signals of the first and second transmission / reception cycles change with time. On the other hand, for the stationary object, the beat signals of the first and second transmission / reception cycles do not change with time.

In the lower middle part of FIG. 3, the difference signal calculation unit 12 sets the time corresponding to the reception start time t _R1 and t _R2 to 0 for each beat signal of the first and second transmission / reception cycles, and sets the transmission end time t _T1 and t. _Let t _B be the time corresponding to _T2 . Then, the difference signal calculation unit 12 calculates the difference signal between the beat signals of the first and second transmission / reception cycles after making the time origins corresponding to the reception start times t _R1 and t _{R2 the} same as described above.

In the middle of FIG. 3, a moving object exists within the detection distance range. Here, the beat signals of the first and second transmission / reception cycles are time-varying. Then, the difference signal calculation unit 12 maintains the frequency component corresponding to the moving object target distance in the difference signal between the beat signals of the first and second transmission / reception cycles. Therefore, the moving object detection unit 13 can detect that the intensity of the difference signal between the beat signals of the first and second transmission / reception cycles is equal to or higher than the predetermined signal intensity and the moving object is present within the detection distance range. it can. Then, the moving object target detection unit 13 can execute frequency conversion of the difference signal between the beat signals of the first and second transmission / reception cycles, and can execute the measurement of the moving object target distance d _M1 .

As shown in the middle of FIG. 3, when the moving object target speed is low, the moving object target distances in the first and second transmission / reception cycles are almost equal, and the peak distances of the distance spectra in the first and second transmission / reception cycles are not separated. .. As a modification, when the moving object target speed is high, the moving object target distances in the first and second transmission / reception cycles are significantly different, and the peak distances in the distance spectra of the first and second transmission / reception cycles are separated.

In the lower part of FIG. 3, only a stationary object is present within the detection distance range. Here, the beat signals of the first and second transmission / reception cycles do not change with time. Then, the difference signal calculation unit 12 removes the frequency component corresponding to the stationary object reference distance in the difference signal between the beat signals of the first and second transmission / reception cycles. Therefore, the moving object detection unit 13 can detect that the intensity of the difference signal between the beat signals of the first and second transmission / reception cycles is lower than the predetermined signal intensity and the moving object does not exist within the detection distance range. .. Then, moving target detection unit 13, it is possible to cancel the frequency conversion of the difference signal between the beat signals of the first and second transmitting and receiving cycle, to stop the measurement of the stationary target distance d _S.

In this way, when detecting a moving object, the moving object can be distinguished from the stationary object. Then, since the difference signal or the beat signal is frequency-converted only when the moving object target is detected, the calculation load, the storage capacity, and the power consumption can be reduced.

In FIG. 4, the moving object target detecting unit 13 detects that a moving object target moving within the detection distance range exists when the moving object target distances in different transmission / reception cycles are different (NO in step S9) (NO). Step S10). Here, as a moving object, a human being, a vehicle, or the like can be mentioned.

In FIG. 5, the moving object target detection unit 13 rotates or vibrates without moving within the detection distance range when the moving object target distances in different transmission / reception cycles are the same (YES in step S9). Detects the presence of a vibrating object (step S11). Here, examples of the rotation / vibration target include trees, poles, ventilation fans, walls, and the like. After step S11 is executed, steps S12 to S14 are not executed.

Specifically, the beat signal acquisition unit 11 beats from the reception start times t _R1 , t _R2 , and t _R3 to the transmission end times t _T1 , t _T2 , and t _T3 for each of the first, second, and third transmission / reception cycles. Get the signal. Here, with respect to the rotation / vibration target, the beat signals of the first, second, and third transmission / reception cycles change with time. On the other hand, with respect to the moving object, the beat signals of the first, second, and third transmission / reception cycles change with time.

In this way, even for a rotation / vibration target whose target distance does not change, the beat signals of the first, second, and third transmission / reception cycles change with time, so that the difference signal between the beat signals of the first, second, and third transmission / reception cycles is changed. The intensity of is finite. Therefore, the rotation / vibration target cannot be distinguished from the moving target based only on the strength of the difference signal between the beat signals of the first, second, and third transmission / reception cycles.

In the middle and lower stages of FIGS. 4 and 5, the difference signal calculation unit 12 sets the time corresponding to the reception start times t _R1 , t _R2 , and t _R3 to 0 for each beat signal of the first, second, and third transmission / reception cycles. , The time corresponding to the transmission end time t _T1 , t _T2 , and t _{T 3} is t _B. Then, the difference signal calculation unit 12 sets the same time origin corresponding to the reception start times t _R1 , t _R2 , and t _R3 as described above, and then sets the difference signal between the beat signals of the first and second transmission / reception cycles and The difference signal between the beat signals of the second and third transmission / reception cycles is calculated.

In the lower middle part of FIG. 4, a moving object is present within the detection distance range. Here, the beat signals of the first, second, and third transmission / reception cycles are time-varying. Then, the difference signal calculation unit 12 maintains the frequency component corresponding to the moving object target distance in the difference signal between the beat signals of the first and second transmission / reception cycles and the difference signal between the beat signals of the second and third transmission / reception cycles. ing. Therefore, the moving object detection unit 13 detects that the strength of the difference signal between the beat signals of the first and second transmission / reception cycles and the strength of the difference signal between the beat signals of the second and third transmission / reception cycles are equal to or higher than the predetermined signal strength. It is possible to detect the presence of a moving target or a rotating / vibrating target within the distance range. Then, the moving object target detection unit 13 has a different moving object targeting distance d _{M1 in the first} and second transmission / reception cycles and a moving object targeting distance d _M2 in the second and third transmission / reception cycles, and is within the detection distance range. It is possible to detect the presence of a moving target rather than a rotating / vibrating target.

As shown in the lower middle of FIG. 4, when the moving object target speed is low, the moving object target distances of adjacent transmission / reception cycles are almost equal, and the peak distances of the distance spectra of adjacent transmission / reception cycles are not separated, but slightly. The peak distances of the distance spectra of the distant transmission / reception cycles are separated. As a modification, when the moving object target speed is high, the moving object target distances of adjacent transmission / reception cycles are significantly different, and the peak distances of the distance spectra of adjacent transmission / reception cycles are separated, so that the transmission / reception cycles are slightly separated. It is not necessary to detect the peak distance of the distance spectrum of.

In the lower middle part of FIG. 5, a rotation / vibration target exists within the detection distance range. Here, the beat signals of the first, second, and third transmission / reception cycles are time-varying. Then, the difference signal calculation unit 12 determines the frequency component corresponding to the rotation / vibration object reference distance in the difference signal between the beat signals of the first and second transmission / reception cycles and the difference signal between the beat signals of the second and third transmission / reception cycles. Maintained. Therefore, the moving object detection unit 13 detects that the strength of the difference signal between the beat signals of the first and second transmission / reception cycles and the strength of the difference signal between the beat signals of the second and third transmission / reception cycles are equal to or higher than the predetermined signal strength. It is possible to detect the presence of a rotating / vibrating target or a moving target within a range of distances. Then, moving target detection unit 13, a moving target distance d _R in the first and second transmitting and receiving cycle, the moving target distance d _R in the second and third transmitting and receiving cycle, but the same detection distance range It is possible to detect the presence of a rotating / vibrating target rather than a moving target inside.

In this way, after frequency conversion of the difference signal or the beat signal, the rotation / vibration target can be distinguished from the moving target based on the fact that the moving object distances of different transmission / reception cycles are the same.

From FIG. 3 to FIG. 5, the moving object detection unit 13 executes frequency conversion of the difference signal between the beat signals of the first and second (including the third in FIGS. 4 and 5) transmission / reception cycles. Perform measurement of moving object target distance. As a modification, the moving object detection unit 13 executes frequency conversion of each of the beat signals of the first and second (including the third according to FIGS. 4 and 5) transmission / reception cycle, and the moving object target distance. You may perform the measurement of. From FIG. 3 to FIG. 5, the moving object detection unit 13 can reduce the calculation load, the storage capacity, and the power consumption. In the modified example, the moving object target detecting unit 13 can distinguish in which direction the moving object target distance has changed over time, a long distance or a short distance.

From FIG. 3 to FIG. 5, the difference signal calculation unit 12 calculates the difference signal between the beat signals of the first and second (including the third in FIGS. 4 and 5) transmission / reception cycles, and detects the moving object. The unit 13 detects when the strength of the difference signal between the beat signals of the first and second (including the third in FIGS. 4 and 5) transmission / reception cycle is equal to or higher than the predetermined signal strength / lower than the predetermined signal strength. Detects the presence / absence of a moving target within the distance range. As a modification, the difference signal calculation unit 12 calculates the division signal between the beat signals of the first and second (including the third according to FIGS. 4 and 5) transmission / reception cycle, and the moving object detection unit 13 1st and 2nd (including the 3rd according to FIGS. 4 and 5) moves within the detection distance range when the strength of the division signal between the beat signals of the transmission / reception cycle changes with time / does not change with time. It may be detected that the target exists / does not exist.

In FIG. 6, the moving object detection unit 13 detects when the beat frequencies are the same and the beat phases are different between the I, Q components A / D I, and A / D Q of the beat signals having different transmission / reception cycles. Detects the presence of a rotating / vibrating object that rotates or vibrates without moving within range. Here, examples of the rotation / vibration target include trees, poles, ventilation fans, walls, and the like. After FIG. 6 is executed, steps S12 to S14 are not executed.

Specifically, the beat signal acquisition unit 11 starts transmitting from the reception start times t _R1 , t _R2 , t _R3 , and t _R4 for each of the first, second, third, and fourth transmission / reception cycles, and the transmission end times t _T1 , t _T2 , and t. Acquires beat signals up to _T3 and _tT4 . Here, with respect to the rotation / vibration target, the beat frequencies of the first, second, third, and fourth transmission / reception cycles do not change with time, but the beat phases of the first, second, third, and fourth transmission / reception cycles change with time. On the other hand, for moving objects, the beat frequencies of the first, second, third, and fourth transmission / reception cycles change with time, and the beat phases of the first, second, third, and fourth transmission / reception cycles also change with time.

As described above, even for the rotation / vibration target whose target distance does not change, the beat frequency of the first, second, third, and fourth transmission / reception cycles does not change with time, but the beat signal of the first, second, third, and fourth transmission / reception cycles. Since the time changes with time, the strength of the difference signal between the beat signals of the first, second, third, and fourth transmission / reception cycles becomes a finite value. Therefore, the rotation / vibration target cannot be distinguished from the moving target only based on the strength of the difference signal between the beat signals of the first, second, third, and fourth transmission / reception cycles.

In the lower part of FIG. 6, the difference signal calculation unit 12 sets the time corresponding to the reception start times t _R1 , t _R2 , t _R3 , and t _R4 to 0 for each of the beat signals of the first, second, third, and fourth transmission / reception cycles. _Let t _B be the time corresponding to the transmission end time t _T1 , t _T2 , t _T3 , and t _{T 4} . However, the difference signal calculation unit 12 sets the time origins corresponding to the reception start times t _R1 , t _R2 , t _R3 , and t _R4 to be the same, and then between the beat signals of the first, second, third, and fourth transmission / reception cycles. It does not calculate the difference signal.

In the lower part of FIG. 6, a rotation / vibration target exists within the detection distance range. Here, the beat frequencies of the first, second, third, and fourth transmission / reception cycles do not change with time, but the beat phases of the first, second, third, and fourth transmission / reception cycles change with time. Then, the moving object detection unit 13 detects that the I and Q components at a certain time change with time as shown by the black circles in the beat signals of the first, second, third, and fourth transmission / reception cycles. Therefore, the moving object detection unit 13 can detect that the moving / vibrating object does not exist within the detection distance range but the rotating / vibrating object exists. Further, the moving object detection unit 13 can measure the rotation / vibration velocity of the rotation / vibration object based on the time change of the I and Q components at a certain time in the beat signals having different transmission / reception cycles.

In this way, the rotation / vibration target can be distinguished from the moving target based on the fact that the beat frequencies of different transmission / reception cycles are the same before the frequency conversion of the difference signal or the beat signal.

The configuration of the moving object detection unit of the present disclosure is shown in FIG. The moving object detection unit 13 is a difference signal I, Q component SUB I, SUB Q (shown in FIG. 7) or a beat signal I, Q component A / D I, A / D Q (not shown in FIG. 7). The sampling frequency and the modulation frequency with respect to (.) Are adjusted, and the measurement resolution and the measurement range with respect to the moving object target distance are adjusted (step S3).

Specifically, the moving object detection unit 13 is composed of mixer circuits 131I, 131Q, low-pass filters 132I, 132Q, decimeter / interpolator 133I, 133Q, and frequency converter 134. The mixer circuits 131I and 131Q modulate the I and Q components SUB I and SUB Q of the difference signal at a desired modulation frequency. The low-pass filters 132I and 132Q pass only the necessary low frequency components from the I and Q components MOD I and MOD Q of the difference signal. The decimeter / interpolator 133I and 133Q sample the I and Q components LPF I and LPF Q of the difference signal at a desired sampling frequency. The frequency converter 134 frequency-converts the I and Q components SAM I and SAM Q of the difference signal.

Here, the frequency measurement resolution _{is F S} / FFT (F S is the sampling frequency, FFT is a frequency conversion degree.). Accordingly, distance measurement resolution _{is, ((F S / FFT)} × S T × c 0) / a _{(2 × F W) (S} T sweep duration, _{c 0} is the speed of light, _{F W} sweep frequency width. ). The longest measured distance is _{((F S / 2) ×} S T × c 0) / (2 × F W).

Therefore, if limiting the measurement range at a short distance, it suffices to reduce the sampling frequency F _S in formulas longest measurement distance, it is possible to improve the distance measurement resolution. However, if extending the measurement range to long range, the sampling frequency F _S in formulas longest measured distance may be increased, but it is possible to improve the distance measurement resolution. Therefore, when extending the measurement range to a long distance, in order to improve the distance measurement resolution, after changing the lower limit of the measurement range from 0 to a finite value, the longest measurement distance (from the lower limit of the measurement range) the sampling frequency F _S in the formula may be too large. Then, in order to change the lower limit of the measurement range from 0 to a finite value, the mixer circuits 131I and 131Q modulate the I and Q components SUB I and SUB Q of the difference signal at a desired modulation frequency, and the low-pass filter 132I, The 132Q passes only the necessary low frequency components from the I and Q components MOD I and MOD Q of the difference signal.

By setting the sampling frequency of the difference signal or the beat signal to a low frequency in this way, the measurement resolution can be improved at a short distance and a long distance without increasing the order of frequency conversion of the difference signal or the beat signal. Can be done. Then, by setting the modulation frequency of the difference signal or beat signal to low frequency / high frequency, that is, by setting the lower limit of the measurement range to short distance / long distance, the order of frequency conversion of the difference signal or beat signal. The measurement resolution can be improved at a short distance / a long distance without increasing the frequency.

The output of the moving object target distance of the present disclosure is shown in FIG. The moving object target detection unit 13 discards the moving object target distance not included in the predetermined distance range and does not output it (NO in step S12 and step S13). On the other hand, the moving object target detecting unit 13 adopts and outputs the moving object target distance included in the predetermined distance range (YES in step S12 and step S14).

The left column of FIG. 8 indicates when only a short distance is the detection target (human or vehicle, etc.) or when there is a noise source (tree, pole, ventilation fan, wall, etc.) at a long distance. Here, the moving object target detection unit 13 discards and does not output the moving object target distance d _M2 that is not included in the predetermined distance range that is shorter than the target distance threshold d _Th . On the other hand, the moving object target detection unit 13 adopts and outputs the moving object target distance d _M1 included in a predetermined distance range shorter than the target distance threshold d _Th .

The right column of FIG. 8 indicates when only a long distance is to be detected (human or vehicle, etc.), or when there is a noise source (tree, pole, ventilation fan, wall, etc.) at a short distance. Here, the moving object target detection unit 13 discards and does not output the moving object target distance d _M1 that is not included in the predetermined distance range far from the target distance threshold d _Th . On the other hand, the moving object target detection unit 13 adopts and outputs the moving object target distance d _M2 included in a predetermined distance range far from the target distance threshold d _Th .

In this way, when only a short distance / long distance is to be detected, or when there is a noise source at a long distance / short distance, only the short distance / long distance can be adopted and output.

For example, by distinguishing the rotation of the ventilation fan inside and outside the elevator or the vibration of the wall from the movement of a person inside and outside the elevator, it is possible to prevent the automatic door of the elevator from being erroneously opened and closed. Alternatively, by distinguishing the rotation of the ventilation fan in the emergency stairs or the vibration of the wall from the movement of a human in the emergency stairs, it is possible to prevent the automatic lighting of the emergency stairs from being erroneously turned on.

The target detection device, system, program and method of the present disclosure can be applied in an application of detecting a moving person inside or outside an elevator, a moving person inside an emergency staircase, or the like.

S: Target detection system T: Target 1: Target detection device 2: FMCW radar transmission / reception device 11: Beat signal acquisition unit 12: Difference signal calculation unit 13: Moving target detection unit 21: PLL circuit 22: Oscillator 23: Distributor 24: Amplifier 25: Low-pass filter 26: Transmit antenna 27: Receive antenna 28: Amplifier 29: Amplifier 30: Mixer circuit 31I, 31Q: Calibrator 32: A / D converter 33: Phase modulator 131I, 131Q: Mixer circuit 132I, 132Q: Low-pass filter 133I, 133Q: Decimator / Antenna 134: Frequency converter

Claims (9)

A beat signal acquisition unit that acquires beat signals between transmission and reception signals of the FMCW radar,
A difference signal calculation unit that calculates a difference signal between the beat signals having different transmission / reception cycles,
When the strength of the difference signal is equal to or higher than the predetermined signal strength, it is detected that a moving object is present within the detection distance range, and when the strength of the difference signal is lower than the predetermined signal strength, the detection distance range is detected. A moving object detection unit that detects that the moving object does not exist inside,
A target detection device characterized by being equipped with. The moving object detection unit rotates or vibrates without moving within the detection distance range when the beat frequencies are the same and the beat phases are different between the beat signals having different transmission / reception cycles. The target detection device according to claim 1, further comprising detecting the presence of a target. When the moving object detection unit detects that the moving object exists within the detection distance range, the moving object detecting unit frequency-converts the difference signal or the beat signal, and moves the distance to the moving object. When the target distance is measured and it is detected that the moving target does not exist within the detection distance range, the frequency conversion of the difference signal or the beat signal is stopped, and the measurement of the moving target distance is stopped. The target detection device according to claim 1 or 2, wherein the target detection device is characterized by the above. The moving object detection unit has a rotating / vibrating object that rotates or vibrates without moving within the detection distance range when the moving object target distances in the different transmission / reception cycles are the same. The third aspect of the present invention is characterized in that, when the moving object target distances in different transmission / reception cycles are different, the presence of the moving object target moving within the detection distance range is detected. Target detection device. The moving object target detecting unit adjusts the sampling frequency and the modulation frequency for the difference signal or the beat signal, and adjusts the measurement resolution and the measurement range for the moving object target distance, according to claim 3 or 4. The target detection device described in. The moving object target detection unit is characterized in that the moving object target distance not included in the predetermined distance range is discarded and not output, but the moving object target distance included in the predetermined distance range is adopted and output. The target detection device according to any one of claims 3 to 5. A target detection system comprising the target detection device according to any one of claims 1 to 6 and the radar transmission / reception device of the FMCW radar. The beat signal acquisition step of acquiring the beat signal between the transmission / reception signals of the FMCW radar, and
A difference signal calculation step for calculating a difference signal between the beat signals having different transmission / reception cycles, and
When the strength of the difference signal is equal to or higher than the predetermined signal strength, it is detected that a moving object is present within the detection distance range, and when the strength of the difference signal is lower than the predetermined signal strength, the detection distance range is detected. A moving object detection step that detects that the moving object does not exist inside, and
A target detection program that allows a computer to execute The beat signal acquisition step of acquiring the beat signal between the transmission / reception signals of the FMCW radar, and
A difference signal calculation step for calculating a difference signal between the beat signals having different transmission / reception cycles, and
When the strength of the difference signal is equal to or higher than the predetermined signal strength, it is detected that a moving object is present within the detection distance range, and when the strength of the difference signal is lower than the predetermined signal strength, the detection distance range is detected. A moving object detection step that detects that the moving object does not exist inside, and
A target detection method, characterized in that

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