JP2014126391A - Installation sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that, when the object detection device activated by a number of radio wave irradiation and a device irradiating the similar electric waves other than this detection device are located in the same detection area, the presence determination (distance calculation) of the object is frequently interrupted by the mutual interference of the electric waves, and though means for prevention is available, a prevention method is restricted when the number of devices to be arranged is increased.SOLUTION: An electric wave D is irradiated to a detection area K while being modulated in frequency, and a reflection wave R reflected on an object T in the detection area K is received so that a distance of the object T in the detection area K is calculated. The presence of an interference wave G for interrupting the calculation of the distance up to the object T in the detection area K is determined at the time of stoppage of the irradiation of the electric wave D, and signal processing means 5 in which the distance of the object T is calculated by irradiating the electric wave D when it is determined that the interference wave G is not present and the irradiation stoppage of the electric wave D is suspended when it is determined that the interference wave G is present includes a holding excess part 7 for outputting a holding excess signal H when the irradiation stoppage of the electric wave D exceeds a predetermined time.

Description

  The present invention relates to an object detection device that irradiates a detection area with a radio wave, calculates a distance to an object by a reflected wave from an object that has entered the detection area, and determines its presence. Is an object detection that prevents the object distance calculation from being obstructed in advance by radio wave interference that occurs when radio waves are emitted from multiple object detection devices, or by radio waves from an object that has entered the detection area. It relates to the device.

2. Description of the Related Art Conventionally, as an object detection device, a method using an FMCW radar device or the like is known as a method for irradiating a detection area with a radio wave and detecting an object by a reflected wave from an object that has entered the detection area. .
In the case of using a plurality of object detection devices such as the FMCW radar device, the object detection method uses the reflected wave of the radio wave irradiated by itself as a detection means, so that it interferes with the radio wave irradiated from the other, and enters the detection region. In some cases, it may be mistakenly detected as an intruding object.

As shown in FIG. 10, for example, when one object detection device among a plurality of object detection devices receives a radio wave emitted from another object detection device, or receives a reflected wave from an obstacle, radio wave interference occurs. Be triggered.
When an interference wave is generated due to such radio wave interference, even if no object is present in the detection area, the object is present (in FIG. 10, when the object T ′ does not exist, the radio wave Da is represented by Da ′. Although it penetrates like this, the radio waves Db and Dc from other sources and the reflected wave Rd arrive) and it is erroneously determined.

In the case of an FMCW radar apparatus, even if an object is present in the detection area, a beat signal (irradiation) by an interference wave different from the beat signal (difference signal between the irradiated radio wave and the reflected wave) of the reflected wave of the object. May be erroneously determined as if an object other than the existing object is present in the detection region.
In order to prevent the above misjudgment, conventionally, in order to avoid radio wave interference by multiple object detection devices and similar radio wave irradiation devices, the radio wave band used in the detection area is divided by frequency band or time In order to prevent radio interference, radio waves can be used with horizontal polarization and vertical polarization that do not interfere with each other, or a network can be constructed between multiple radar devices. There has been a method of avoiding interference by sequentially switching the object detection timing of each radar device in the network.

However, radio waves that can be used in the detection area are limited to 24.05 GHz or more and 24.25 GHz or less as mobile object detection sensors for specific low-power radio stations. Even if it is done, there are only a few units that can avoid radio interference, and it is difficult to register settings at the time of network construction, and between the switching of each radar device so that radio waves between sequentially switching radar devices are not suffered. There are problems in installing many object detection devices and similar radio wave irradiation devices, such as the need to provide time during which no radio waves are irradiated (that is, time during which no object is detected).
In this way, it is an object to install a large number of object detection devices. Conventionally, railroad crossings using means detection by radar to prevent erroneous detection when an FMCW radar device or the like receives interference from other radar devices, etc. A blocking intruder detection device is known (Patent Document 1).
This radar intruder detection device switches the transmission / reception switch in reverse phase, detects the relative speed and distance between the target and its own radar, and FMCW radar, and at least one reference reflection cross section reflector installed at a fixed distance by the radar. The interference detection is determined by comparing the means for detecting the radar detection reception level with the signal level and threshold when the transmission / reception switching frequency is such that the reception level is null.

JP 2007-86009 A (Patent No. 4813859)

However, since the distance from the at least one reference reflection cross-sectional area reflector to the radar is a fixed distance, the blocking intruder detection device described in the above-mentioned Patent Document 1 simply switches the transmission / reception switch in the reverse phase, so that the reference It can be recognized that the outgoing wave from the radar-equipped vehicle that cuts off between the reflector and the radar returns faster than the reflected wave from the reference reflector that is a fixed distance away, and only false detection can be prevented.
Therefore, when a radio wave is emitted from a radar-equipped vehicle near the reference reflector, it is erroneously detected.
In addition, the blocking intruder detection device disclosed in Patent Document 1 has a large installation condition such that a radar cannot be installed unless it is a fixed distance away from the reference reflector as premised on installation at a level crossing. There are limitations.

  Therefore, the present invention calculates the distance to an object in an environment in which its own radio wave and other radio waves do not cause radio wave interference even if many object detection devices or multiple similar radio wave irradiation devices are installed in the detection area. It is an object of the present invention to realize an object detection apparatus that performs the above.

The object detection device 1 according to the present invention irradiates the detection region K while frequency-modulating the radio wave D, and receives the reflected wave R reflected by the object T in the detection region K. An object detection device that calculates the distance of the object T at the time when the irradiation of the radio wave D is stopped, the presence of an interference wave G that hinders the calculation of the distance to the object T in the detection region K is determined, and the interference wave G The signal processing means 5 that irradiates the radio wave D to determine the distance of the object T when it is determined that it does not exist, calculates the distance of the object T, and suspends the irradiation stop of the radio wave D when it determines that the interference wave G exists. A first feature is that it includes a hold excess unit 7 that outputs a hold excess signal H when the irradiation stop of D exceeds a predetermined time.
Note that the radio wave D in the present invention refers to an electromagnetic wave having a frequency of 3 THz or less, particularly a microwave having a frequency of 300 MHz to 3 THz, as in the general definition of radio waves. When the object detection apparatus 1 is installed as the moving body detection sensor of the specific low-power radio station described above, the radio wave D having a frequency of 24.05 GHz or more and 24.25 GHz or less is used.

Here, in general, the interference of waves including the radio wave D means that a plurality of waves are overlapped to generate a new wave, and the interference of the waves is between highly correlated waves. It appears prominently, and occurs, for example, when waves having the same generation source or waves having similar values or the same value overlap each other.
Accordingly, in the present invention, only the radio wave D (or reflected wave R) irradiated by the object detection device 1 and the radio wave (jamming wave Z) having a frequency close to or the same value as that of the object detection device 1 cause radio wave interference, and the object detection device 1 It will interfere with the distance calculation.
That is, as shown in FIG. 10, when a plurality of object detection devices 1a to 1d are installed in the same detection region K, for a certain object detection device 1a, radio waves Db and Dc from other object detection devices 1b and 1c, The reflected wave Rd obtained by reflecting the radio wave Dd from the object detection device 1d by the object T can be the interference wave Z.
Therefore, in the present invention, it is only necessary to assume that the jamming wave Z has a frequency F3 of the jamming wave Z that is the same as or close to the frequency band of the radio wave D and the reflected wave R.

  In addition, the interference wave G in the present invention is strictly a wave consisting only of the interference wave Z, or the interference wave Z and the radio wave D irradiated, or the interference wave Z and the radio wave D and the reflection wave thereof. R is a wave that is superimposed due to radio wave interference, which affects the frequency and amplitude of the reflected wave R, and as a result, interferes with the distance calculation to the object T. Incidentally, if the interference wave Z has the same value as or close to the frequency band of the radio wave D or the reflected wave R, in addition to the frequency F3, its amplitude and phase elements also affect the frequency and amplitude of the reflected wave R. give.

  The second feature of the object detection device 1 according to the present invention is that the radio wave D is irradiated to the detection region K while frequency-modulating the radio wave D, and the reflected wave R reflected by the object T in the detection region K is received. An object detection device for calculating the distance of the object T in the detection region K, and determining the presence of an interference wave G that prevents the calculation of the distance to the object T in the detection region K when the irradiation of the radio wave D is stopped; Signal processing means that calculates the distance of the object T by irradiating the radio wave D when it is determined that the interference wave G does not exist, and suspends the irradiation stop of the radio wave D when it is determined that the interference wave G exists. 5 is that an interference prediction unit 8 that predicts a change in the interference wave G from the history of the presence determination of the interference wave G is provided.

  A third feature of the object detection device 1 according to the present invention is that the radio wave D is irradiated to the detection region K while frequency-modulating the radio wave D, and the reflected wave R reflected by the object T in the detection region K is received. An object detection device for calculating the distance of the object T in the detection region K, and determining the presence of an interference wave G that prevents the calculation of the distance to the object T in the detection region K when the irradiation of the radio wave D is stopped; Signal processing means that calculates the distance of the object T by irradiating the radio wave D when it is determined that the interference wave G does not exist, and suspends the irradiation stop of the radio wave D when it is determined that the interference wave G exists. 5 is that the distance to the object T in the detection region K is calculated once for each irradiation of the radio wave D.

With these features, the object detection device 1 according to the present invention determines the interference wave G while stopping the irradiation of the radio wave D, and irradiates the radio wave D that is not necessary for the determination when the presence of the interference wave G is determined. By not doing so, it is possible to reduce the probability of interference by eliminating unnecessary interference due to radio waves D from a plurality of object detection devices 1, and to improve the accuracy of interference wave G determination.
At the same time, there is no restriction such as installation at a fixed distance from the reference reflector, and whether the source of the interference wave G is in the vicinity of the reference reflector as in Patent Document 1 or the like. Regardless, false detection of the interference wave G can be reduced.
In addition, the presence of the interference wave G in the detection region K is determined by the signal processing means 5 when the irradiation of the radio wave D is stopped, and the radio wave D is irradiated when it is determined that the interference wave G is not present. By calculating the distance and deferring the irradiation stop of the radio wave D when it is determined that the interference wave G exists, the network construction at the installation site of the object detection device 1 and the registration setting to the constructed network become completely unnecessary. The irradiation timing of the radio wave D of each object detection device 1 is not restricted by the time required for synchronous communication between the devices 1.
Further, as in the case of constructing a network, there is no need for a time during which no radio wave is irradiated between the switching of each radar device, and if each object detection device 1 has a gap within a period in which no interference wave G exists. This is a state in which the user himself / herself radiates the radio wave D to calculate the distance, and the object detection is performed in a state of competing with each other, so that no time is detected when no object is detected.
When notifying by the hold excess signal H that the irradiation stop of the radio wave D has exceeded a predetermined time, the presence of the object detection apparatus 1 on which the radio wave D is held off is transmitted to the user of the apparatus 1, and this user However, it is possible to check the object T in the detection area K, or to cancel the hold by correcting the installation position of the object detection device 1, and to install a plurality of object detection devices 1 that have been installed with higher reliability. Can be provided.
In addition, by providing the signal processing means 5 with the retention excess section 7 for outputting the retention excess signal H, the object detection device is more effective than the case where the retention excess section 7 is separately provided outside the signal processing means 5. 1 can be made compact, and the signal processing means 5 and the retention excess portion 7 can be manufactured integrally, so that the production efficiency is improved.

Further, when predicting a future change of the interference wave G from the history of the presence determination of the interference wave G, if it is determined that there is no time for irradiation of the radio wave D, the presence determination of the interference wave G As the history is stored, it can be used to determine when the interference wave G comes next, and by combining the prediction of the interference wave G, more reliable object detection can be performed.
In addition, by providing the signal processing means 5 with the interference prediction unit 8 that predicts future changes in the interference wave G, the object detection device 1 can be made compact and the production efficiency can be improved as described above. .

Then, when the distance to the object T is calculated once for each irradiation of the radio wave D (when the radio wave D is not irradiated during a period not necessary for the determination), an extra amount due to the radio waves D from the plurality of object detection devices 1 is calculated. Therefore, the time required for each sweep is shorter than in the prior art, that is, the time for stopping the irradiation of the radio wave D of each object detection device 1 is shortened. The number of detection devices 1 that can be used simultaneously increases significantly.
Conventionally, the calculation speed of the signal processing means 5 may be slower than the time required for one irradiation of the radio wave D.

Incidentally, if the number of devices that can be used simultaneously is illustrated and compared, in the case of a conventional FMCW radar device, in order not to interfere with each other, the frequency band of 24.05 GHz to 24.25 GHz is divided (substantially about two categories), Even when the horizontal polarization and the vertical polarization are used for each division, there are at most four divisions (that is, the maximum number of simultaneous use is four).
However, in the object detection device 1 according to the present invention, assuming that the measurement distance to the object T is 200 m, the frequency of the beat signal of the reflected wave R and the radio wave D is about 250 kHz at the maximum, as will be described later. If this beat margin is doubled and the frequency of the beat signal is 500 kHz or more for each object detection device 1, it does not affect the detection of each other, so the available frequency band is 24.25 GHz-24.05 GHz = 200 MHz. Even if it takes a margin of 10 MHz above and below and is estimated to be 180 MHz, 180 MHz ÷ 500 kHz = 360 units, that is, the number of units that can be used in the 180 MHz frequency band can be calculated as 360 units. It becomes possible to greatly increase.

  The presence of an interference wave in the detection area is determined when radio wave irradiation stops, and the object distance is calculated by irradiating the radio wave when it is determined that there is no interference wave, and radio wave irradiation is performed when it is determined that the interference wave exists. By suspending the stop, it becomes possible to detect an object in an environment free from radio wave interference and prevent erroneous determination.

It is a block diagram which shows the structural example of the object detection apparatus of this invention. It is a figure which shows the example of an object detection pattern when there is no interference wave. It is a figure which shows the difference signal and interference example when there exists an interference wave. It is a figure which shows the example of the structure which performs presence determination of an interference wave. It is a flowchart figure of Example 1 of this invention. It is a time chart figure explaining Example 1 of this invention. It is a flowchart figure of Example 2 of this invention. It is a flowchart figure of Example 3 of this invention. It is a time chart figure explaining Example 3 of this invention. It is the schematic which showed the environment where a radio wave interference generate | occur | produces.

An embodiment of the present invention will be described in detail with reference to FIGS.
<Usage environment, overall configuration>
FIG. 1 is a block diagram showing a configuration of an FMCW radar apparatus that is an example of an object detection apparatus 1 according to the present invention, and is a block diagram that is commonly used.
For example, as shown in FIG. 10, the object detection device 1 of the present invention may cause radio wave interference for a certain object detection device 1a in a predetermined detection region K where a plurality of object devices 1a to 1d are installed. Also used in the environment (environment in which radio waves Db and Dc from other object detection devices 1b and 1c and a reflected wave Rd reflected by the object T from the other object detection device 1d can be incident as an interference wave Z) it can.
The object detection apparatus 1 includes an irradiation unit 2 that irradiates a detection region K with a radio wave D (hereinafter referred to as “irradiation wave D”), a reception unit 3 that receives a reflected wave R or an interference wave G, and a reflected wave R or interference. Difference output means 4 for outputting a difference signal V between the wave G and the irradiation wave D and signal processing means 5 for calculating a distance to the object T based on the difference signal V are provided.

<Irradiation means 2>
As shown in FIG. 1, the irradiation means 2 outputs a basic signal M (a signal having a frequency and amplitude equivalent to the irradiation wave D, or an interference reference signal N described later) capable of modulating the frequency, The basic signal M is used as the irradiation wave D, and the irradiation wave D can be irradiated freely while the frequency is modulated.
Here, “irradiation free” means a case where the irradiation wave D is emitted while outputting the basic signal M, and a case where the irradiation of the irradiation wave D is stopped and only the basic signal M is output.
As described above, the irradiating unit 2 may have any structure as long as it can freely irradiate the irradiation wave D while outputting the basic signal M, but may have the following configuration, for example.
In the present invention, the fundamental signal M whose frequency can be modulated is a signal (signal corresponding to the radio wave D) having the same frequency and amplitude as the radio wave D emitted by the irradiation means 2, or an interference reference signal. N.
Further, the interference reference signal N in the present invention has a frequency capable of interfering with the radio wave D or the reflected wave R. When the difference output means 4 obtains a difference (differential interference signal S) from the interference wave G, the interference reference signal N A signal that serves as a reference for existence determination. Further, the amplitude of the interference reference signal N may be the same value or a value close to the amplitude of the signal corresponding to the reflected wave R.

First, the irradiation means 2 has a modulation signal generator 21 that can generate a signal whose amplitude can be arbitrarily modulated (the amplitude may be constant). A transmission amplifier 22 for amplifying a signal, a transmission switch 23 for opening / closing a path from the transmission amplifier 22 to a transmission antenna 24 described later, and a basis from the transmission amplifier 22 when the transmission switch 23 is closed (ON) A transmission antenna 24 for irradiating the detection area K with the signal M is provided.
A path (path L1) for outputting the basic signal M is provided between the transmission amplifier 22 and the transmission switch 23 (on the downstream side of the transmission amplifier 22 and on the upstream side of the transmission switch 23). It is sufficient that the irradiation wave D can be irradiated while outputting, and the configuration of the transmission switch 23 is not limited, and a cover or the like that closes the transmission antenna 24 and suppresses the irradiation wave D may be used.
Further, the irradiation range / angle of the irradiation wave D is not particularly limited. For example, the irradiation angle is wider than the left / right direction, or vice versa, or vice versa. The irradiation angle may be substantially the same.

<Receiving means 3>
As shown in FIG. 1, the reception unit 3 reflects the reflected wave R reflected from the irradiation wave D irradiated from the transmission antenna 24 of the irradiation unit 2 while modulating the frequency with the object T in the detection region K. Alternatively, the interference wave G that prevents the distance calculation to the object T is received.
For this reason, the receiving means 3 includes a receiving antenna 25 that receives the reflected wave R or the interference wave G and makes a signal corresponding thereto, and a receiving amplifier 26 that amplifies the signal from the receiving antenna 25.
In general, the transmission antenna 24 and the reception antenna 25 may be separated from each other, and the configuration may be simplified as one antenna (patch antenna or the like).

<Difference output means 4>
The difference output means 4 is a mixer 27 that outputs a difference signal V between the wave received by the reception means 3 and the basic signal M from the irradiation means 2.
As shown in FIG. 1, the input to the mixer 27 includes a path L1 for inputting a basic signal M (a signal corresponding to the irradiation wave D or an interference reference signal N) from the irradiation unit 2, and a reception unit 3. There are two paths L2 for inputting a signal (a signal corresponding to the reflected wave R or the interference wave G) from the (reception amplifier 26).
Further, the frequency of the signal in the path L1 from the irradiation unit 2 is F1, and the frequency of the signal in the path L2 from the reception unit 3 is F2.

On the other hand, the output of the mixer 27 which is the difference output means 4 is basically (1) the beat difference signal B between the signal corresponding to the irradiation wave D and the signal corresponding to the reflected wave R (that is, B = D−R). ) And (2) an interference difference signal S (S = NG) between the above-described interference reference signal N and a signal corresponding to the interference wave G.
That is, (1) is a case where B = D−R, the interference wave G is not generated, and the distance to the object T is determined by the beat difference signal B between the irradiation wave D and the original reflected wave R. It is in an environment where it can be calculated.
Further, (2) is a case where S = NG, where an interference wave G is generated, but under an environment where the presence of the interference wave G can be determined by the interference difference signal S with respect to the interference reference signal N. It is.

The circuit forming the mixer 27 inputs (mixes) the basic signal M from the irradiation unit 2 and the signal from the reception unit 3 (a signal corresponding to the reflected wave R or the interference wave G), and the frequency of each signal is determined. This is a circuit in which the difference is the frequency of the output signal.
Specifically, the mixer 27 includes an analog multiplier circuit (a multiplier circuit using a differential amplifier circuit, a multiplier circuit using a logarithmic conversion), a mixer using distortion (an active mixer using a transistor, a passive mixer using a diode). Or any other configuration.
Incidentally, regardless of the configuration, the mixer 27 multiplies the basic signal M and the signal from the receiving means 3 by the product-sum formula of the following equation (1), and then the difference between the frequencies (F1−F2). Only the component is extracted by a filter or the like.

As shown in equation (1), the amplitude of the differential signal V output from the mixer 27 includes the amplitude A ₁ of the basic signal M and the signal (reflected wave R or interference wave G) from the receiving means 3. despite multiplied by the amplitude a ₂ of the corresponding signal) becomes 1/2.
Therefore, for example, when there is no interference wave G, except for noise, the signal from the receiving means 3 (signal corresponding to the interference wave G) has an amplitude A ₂ of 0 (frequency F2 is also 0). Even when the signal M is multiplied, the amplitude of the difference signal V of the mixer 27 becomes 0 (the frequency (F1-F2) is also 0).

<Signal processing means 5>
The signal processing means 5 calculates the distance to the object T in the detection region K based on the difference signal V from the difference output means 4 (mixer 27), and the presence of the interference wave G based on the difference signal V. It is provided with an interference determination unit 6 for determining
In addition, the signal excess means 7 and the interference prediction unit 8 are also provided in the signal processing means 5 (signal processing circuit 32).
As shown in FIG. 1, specifically, the signal processing means 5 includes a distance band-pass filter 28 (hereinafter referred to as “distance BPF 28”) that passes the difference signal V from the mixer 27 only in a predetermined frequency band, An A / D converter 29 that converts a signal (analog signal) from the distance BPF 28 into a digital signal, and an interference bandpass filter 30 that passes the difference signal V from the mixer 27 only in a predetermined frequency band (hereinafter referred to as “interference BPF 30”). ) And an interference wave determination unit 31 that determines the presence of the interference wave G based on the signal from the interference BPF 30, and processes signals from the interference wave determination unit 31 and the A / D converter 29 to generate a modulated signal. And a signal processing circuit 32 for giving a command to the transmitter 21 and the transmission switch 23.
The interference BPF 30 and the interference wave determination unit 31 are combined to form the interference determination unit 6, and the band pass filter is a band pass filter. As shown in FIG. 1, the A / D converter 29 and the interference wave determination unit 31 are provided in the signal processing circuit 32, but may be provided outside the signal processing circuit 32.

Below, the flow of control of the irradiation means 2, the receiving means 3, and the difference output means 4 by the signal processing means 5 is shown.
Based on the instruction signal C1 for generating the frequency modulation signal corresponding to the irradiation wave D by the signal processing circuit 32, the modulation signal generator 21 generates a frequency modulation signal modulated to an arbitrary frequency.
This frequency modulation signal is amplified by the transmission amplifier 22 to become the basic signal M, and this basic signal M is sent to the mixer 27 through the path L1.
The basic signal M is emitted as an irradiation wave D (radio wave D) from the transmission antenna 24 when the transmission switch 23 is closed (ON) by the radio wave irradiation instruction signal C2 from the signal processing circuit 32. On the contrary, when the transmission switch 23 is opened (OFF), only the basic signal M is output without being irradiated with the irradiation wave D.

The irradiation wave D (radio wave D) irradiated from the transmission antenna 24 is reflected by an obstacle such as the object T that has entered the detection region K, and is received by the reception antenna 25 as a reflected wave R.
The reflected wave R is originally reflected by the object T while the irradiated wave D irradiated while being modulated is reflected by the object T while the reflected wave R is also modulated.
A signal corresponding to the reflected wave R received by the receiving antenna 25 is mixed with the basic signal V from the irradiation means 2 by the mixer 27 through the receiving amplifier 26.
Further, as described above, since the frequency of the signal from the irradiation means 2 (transmission amplifier 22) is F1, and the frequency of the signal from the reception means 3 (reception amplifier 26) is F2, it is an output from the mixer 27. The difference signal V is a signal having a frequency (F1-F2).

The output of the mixed mixer 27 (difference output means 4) is guided to the distance BPF 28 and the interference BPF 30, and these output signals are input to the signal processing circuit 32 to calculate the distance to the object T and to calculate the interference wave G. Existence determination is performed.
In the presence determination of the interference wave G, the output signal of the interference BPF 30 is guided to the signal processing circuit 32 through the interference wave determination unit 31 (comparator or the like), and interference wave determination processing is performed.
On the other hand, the output signal of the distance BPF 28 is A / D converted by the A / D converter 29 and guided to the signal processing circuit 32, where the frequency analysis process described below is performed and the object detection process is performed.

<Example of object detection pattern>
FIG. 2 is a diagram illustrating an example of an object detection pattern in a state where there is no interference wave G.
The irradiation wave D emitted from the transmission antenna 24 can be set to a predetermined sweep time and frequency fluctuation width by the modulation signal generator 21 according to an instruction from the signal processing circuit 32. For example, the pattern <1> in FIG. And the irradiation wave D of <2> is a sawtooth wave and linearly decreases by the frequency fluctuation width Δf during the sweep time ΔT.

Pattern <1> is a diagram illustrating a state in which the object T is not present in the detection region K. Since there is no object T, naturally the reflected wave R from the object T cannot be received by the receiving antenna 25, and the differential signal V itself that is the output from the mixer 27 is not generated.
Pattern <2> is a diagram for explaining a state in which the object T is present in the detection region K. The irradiation wave D irradiated from the transmission antenna 24 is reflected by the object T and received by the reception antenna 25 with a delay of time (delay time) Δτ. This delay time Δτ is proportional to the distance to the object T.
In this pattern <2>,

Is established. That is, it can be seen that the frequency (F1-F2) of the beat difference signal B is proportional to the delay time Δτ (that is, the distance to the object T).

Incidentally, if the pass band of the distance BPF 28 provided for the beat difference signal B is mentioned, the farther the distance from the object T is, the farther the beat difference signal B is, the more the irradiation wave D is reflected by the object T and returns. By the time, the reflected wave R is weakened, the S / N ratio is deteriorated (the ratio of the noise component is large), and the frequency analysis processing cannot be performed. Therefore, there is a maximum measurement distance x to the object T, that is, an upper limit value Fr _max of the frequency (F1-F2) of the beat difference signal B.
Further, when the reflected wave R returns immediately after irradiating the irradiation wave D, the frequency (F1-F2) value of the beat difference signal B becomes very small (low frequency), and time is required for frequency analysis processing. In short, since the processing does not end in real time, there is also a lower limit value Fr _min of the frequency (F1-F2) of the beat difference signal B.
Therefore, the pass band of the distance BPF 28 may be from Fr _{min to} Fr _max .

  Here, the calculation from the frequency of the beat difference signal B to the distance to the object T can be more specifically shown. For example, the sweep time is ΔT, the frequency fluctuation width is Δf, and the frequency of the beat difference signal B is (F1). -F2), when the distance to the object T is x and the speed of light is c,

From this, the delay time Δτ and the sweep speed ΔV are obtained.

When substituting Equations (3) and (4) into Equation (5),

It becomes. Solving this for x,

Is a formula for calculating the distance to the object T.
Therefore, for example, if the sweep time ΔT = 1024 μSec, the frequency fluctuation width Δf = 180 MHz, and the frequency of the beat difference signal B (F1−F2) ≈176 kHz, these are substituted into the above equation (7), and the distance is x≈150 m, and even if the sweep time and frequency fluctuation width are changed to ΔT = 512 μSec and frequency fluctuation width Δf = 90 MHz, the frequency of the beat difference signal B is (F1−F2) ≈117 kHz. If so, the distance can be calculated as x≈100 m.

On the other hand, in order to calculate the maximum measurement distance X to the object T and to calculate the frequency width in the beat difference signal B, the above equation (6) may be used. When the object detection device 1 having the maximum measurement distance X = 210 m to the object T is made, the sweep time ΔT = 1024 μSec and the frequency fluctuation width Δf = 180 MHz are substituted into the above equation (6), and the frequency of the beat difference signal B (F1−F2) ≈246 kHz, and about 250 kHz.
That is, this value of about 250 kHz is the frequency width that the object detection apparatus 1 having a measurement range of about 200 m should ensure at least per unit, and only 500 kHz taking a double margin of about 250 kHz, If the irradiation timings of the irradiation waves D of the object detection devices 1 are separated from each other, no interference occurs between the object detection devices 1 having a measurement range of 200 m.

If this is explained in detail, of the plurality of object detection devices 1a to 1d, the radio wave D irradiated by the device 1a to the detection region K continuously moves away from the frequency immediately after irradiation, but immediately after the irradiation. Even if the next device 1b radiates the radio wave D to the same detection area K after a time of 500 kHz, which is twice as much as 250 kHz corresponding to the reciprocal of the measurement range 200 m from the frequency, the previous device 1 doubles the distance calculation. Has already been completed with no margin, and is not affected at all.
Therefore, even if the third device 1c irradiates the same detection area K with the radio wave D after 500 kHz from the radio wave D irradiation of the second device 1b, the distance calculation of the second device 1b is still affected. Not receive. This can also be said for the third device 1c and the fourth device 1d, and the subsequent devices 1, 1, 1,.

If there is a gap, in the case of each object detection device 1 that calculates the distance by competing with each other, a radio wave separated by 500 kHz exists in the same detection region K at the moment when the device 1 tries to irradiate the radio wave D. However, this radio wave is not recognized as an interference wave G that hinders the distance calculation of the object T (no radio wave interference occurs), and a number of object detection devices 1a, 1b, 1c, and 1d installed in the detection region K. 1, 1, 1,... Continue to irradiate the irradiation wave D (radio wave D) continuously at intervals of 500 kHz, if there is a gap.
For example, if the irradiation wave D of each device 1 decreases linearly by the frequency fluctuation width Δf during the sweep time ΔT as in the patterns <1> and <2> in FIG. The frequency immediately after irradiation of the radio wave D irradiated by the device 1d is the highest frequency (eg, 24.24 GHz) within the available frequency band (eg, width of 180 MHz), but the device 1d emits the radio wave D. Even at the “instant”, the radio waves D (eg: 24.2395 GHz, 24.2390 GHz) in the frequency band lower than the highest frequency (eg, 24.24 GHz) from the previous devices 1a, 1b, 1c. 24.2385 GHz) can be irradiated and can exist without affecting each other.
Therefore, even when this usable frequency band is estimated as low as 180 MHz with a margin of 10 MHz above and below of 24.25 GHz-24.05 GHz = 200 MHz, 180 MHz ÷ 500 kHz = 360 units, that is, in the frequency band of 180 MHz. The number of usable units can be calculated as 360 units.
Further, if 250 kHz, which is 10 times as much as 250 kHz corresponding to the reciprocation of the measurement range of the irradiation wave D, is further set as a margin, 180 MHz ÷ 2500 kHz = 72 units can be used simultaneously.

In the object detection device 1, not only the distance calculation but also the reflection of the reflected wave R, the amplitude (the amplitude of the beat difference signal B), etc. It can be determined whether the object is uniform and easily reflected (such as a car), and the object T in the detection region K can be recognized and determined.
In addition, the irradiation wave D may be reflected from a known object T such as a building or a tree and the reflected wave R may be generated even if the object T is not present in the detection region K. As a method for removing such detection by the reflected wave R from the known object T, there is a process of removing the known object T as compared with the stationary reflected wave R, which is normally performed.

Further, since the actual beat difference signal B is a waveform having various frequency components, it is necessary to obtain the value of the frequency that is contained most in the frequency components.
Therefore, in general, the frequency (F1-F2) spectrum of the beat difference signal B is obtained by applying the Fourier transform formula shown in the following formula (8), and the peak of amplitude or energy is obtained in the spectrum. The frequency component shown is the frequency of the beat difference signal B, and the distance x to the object T is calculated.

  In the pattern <3> in FIG. 2, the irradiation wave D irradiated from the transmission antenna with the object T in the detection region K increases linearly by the frequency fluctuation width Δf during the sweep time ΔT by a sawtooth wave. It is the figure which showed that the object T could be discriminate | determined similarly to the pattern <2> even if the irradiation wave D was used.

  In the pattern <4> in FIG. 2, the irradiation wave D irradiated from the transmission antenna increases linearly by the frequency fluctuation width Δf during the sweep time ΔT, and then linearly by the frequency fluctuation width Δf during the sweep time ΔT. It is the figure which showed that the object T could be discriminate | determined similarly to the pattern <2>, even if it uses the irradiation wave D with the triangular wave which decreases continuously.

  As described above, the irradiation wave D irradiated from the transmission antenna 24 used in the present invention is a sawtooth wave even if the irradiation wave D that linearly decreases by the frequency fluctuation width Δf during the sweep time ΔT (pattern < 1> ・ <2>), even if the irradiation wave D linearly increases by the frequency fluctuation width Δf during the sweep time ΔT with a sawtooth wave (pattern <3>), the frequency fluctuation width during the sweep time ΔT Even if the irradiation wave D is used in the form of a triangular wave that increases linearly by Δf and then decreases linearly by the frequency fluctuation width Δf during the sweep time ΔT (pattern <4>), similar results can be obtained.

<Interference determination unit 6>
Next, the interference determination unit 6 that is a part of the signal processing means 5 will be described.
As shown in FIG. 1, the interference determination unit 6 includes an interference BPF 30 and an interference wave determination unit 31.
As shown by the pattern <5> in FIG. 3, the object T does not exist in the detection region K, but the interference wave Z (such as the radio wave D emitted from another object detection device 1 in FIG. 10). When present, the reception antenna 25 receives the interference wave Z as the interference wave G.
As shown in FIG. 4, the signal corresponding to the interference wave G is amplified by the receiving amplifier 26 and then input to the mixer 27 as a signal of frequency F2, and the interference reference signal N of frequency F1 output from the irradiation means 2 is output. And mixing.
The interference difference signal S, which is the output of the mixer 27 and has the frequency (F1-F2), is input to the interference BPF 30, and then is guided to the interference wave determination unit 31 in the signal processing circuit 32 as an output signal of the interference BPF 30. Then, interference wave determination processing is performed.

In this processing, the signal processing circuit 32 causes the modulation signal generator 21 to generate a signal of a predetermined frequency with the instruction signal C3 for generating the interference reference signal N, and amplifies the signal by the transmission amplifier 22. Therefore, an interference reference signal N that is a reference for determining the presence of the interference wave G is output.
The interference reference signal N has a frequency that can interfere with the radio wave D or the reflected wave R (a frequency close to or the same value as the frequency of the radio wave D or the reflected wave R). It is a signal that serves as a criterion for determination. This interference reference signal N is input from the irradiation unit 2 to the difference output unit 4 (mixer 27) via the path L1. Further, the amplitude of the interference reference signal N may be the same value or a value close to the amplitude of the reflected wave R.
Further, in this process, the transmission switch 23 is opened (OFF) by the signal processing circuit 32 to stop the irradiation of the radio wave D, and control is performed so that the irradiation wave D is not irradiated from the transmission antenna 24.

Here, the interference differential signal S obtained by mixing the interference reference signal N and the signal corresponding to the interference wave G passes only the frequency component in the band set by the interference BPF 30 and is input to the signal processing circuit 32.
That is, unless the passband in the interference BPF 30 is set well, it cannot be correctly recognized whether radio wave interference has occurred.
Therefore, the pass band of the interference BPF 30 will be described below.

When the interference reference signal N exists within the frequency of the irradiation wave D that is actually irradiated and modulated (for object detection by the object detection device 1 itself) as the band of the interference BPF 30 (that is, the frequency is For the irradiation wave D that linearly decreases by the frequency fluctuation width Δf, for example, the signal having the highest and constant frequency immediately after the irradiation of the irradiation wave D is set as the interference reference signal N. The case where the signal having the frequency “is used as the interference reference signal N) will be described.
In this case, since the interference reference signal N has any frequency within the frequency fluctuation range Δf in the radio wave D, if the passband of the interference BPF 30 is set to Fg _min or more and Fg _max or less, the lower limit value Fg _min is

Fg _max which is the upper limit value can be set as

It is sufficient if the interference BPF 30 has such a pass band.
In the above-described example, the frequency immediately after irradiation in the irradiation wave D in which the frequency linearly decreases by the frequency fluctuation width Δf is the frequency of the interference reference signal N. However, the lowest frequency immediately before the irradiation wave D ends irradiation. May be the frequency of the interference reference signal N.
The frequency of the interference reference signal N can also be set at a value that is in the middle of a decrease within the frequency fluctuation range Δf (a value at which the frequency of the interference difference signal S can be 0 while the irradiation wave D is decreasing). .
The interference reference signal N is not limited to a signal having a constant frequency, but may be a signal that is modulated like a sawtooth wave or a triangular wave in FIG.

On the other hand, when the interference reference signal N exists “outside” the frequency of the irradiation wave D that is actually irradiated (that is, a signal having a frequency other than the frequency fluctuation width Δf of the irradiation wave D is defined as the interference reference signal N). Case).
However, if the interference reference signal N is too far from the frequency fluctuation width Δf of the irradiation wave D, even if it is other than the frequency fluctuation width Δf of the irradiation wave D, it is also away from the interference wave G that should be determined to exist. Therefore, the interference reference signal N is set in a range that is a reference for the presence determination of interference.
The lower limit value Fg _{min of the} passband of the interference BPF 30 when the interference reference signal N is present “outside” the frequency of the irradiation wave D is:

And the upper limit Fg _max is

It is sufficient if the interference BPF 30 has such a pass band.
With these settings, the interference difference signal S reflecting the interference wave G reliably passes through the interference BPF 30, and the output signal of the interference BPF 30 is input to the interference wave determination unit 31.

  The interference wave determination unit 31 may have any configuration as long as it can determine whether the amplitude of the output signal of the interference BPF 30 exceeds a predetermined value. For example, the interference wave determination unit 31 outputs the output signal (AC signal) of the interference BPF 30. A configuration may be adopted in which it is determined whether the amplitude of the output signal of the interference BPF 30 has become a certain level or more by converting to direct current and comparing the value with a comparator.

More specifically, the interference wave determination unit 31 includes a converter circuit (forward conversion circuit) that converts an AC signal into a DC signal, and a comparator circuit (comparison circuit) that receives the signal from the converter circuit as one input. Yes.
The interference wave determination unit 31 first converts an output signal (AC signal) from the interference BPF 30 into a DC signal by a converter circuit. The DC signal is used as one input of the comparator circuit, and a threshold DC signal for determining whether the interference wave G exists is input to the other input of the comparator circuit. In addition, an H level signal indicating that the value has been exceeded is output from the comparator circuit.

This threshold DC signal can be determined in view of the interference difference signal S input to the interference wave determiner 31.
The interference difference signal S from the mixer 27 is input to the converter circuit of the interference wave determination unit 31 via the interference BPF 30.
Here, the amplitude in the interference differential signal S is ½ of the product of the amplitude A ₁ of the basic signal M and the amplitude A ₂ of the signal corresponding to the interference wave G, as shown in the above equation (1). In particular, when there is no interference wave G, the amplitude A _{2 of} the signal corresponding to the interference wave G is 0 and the amplitude of the interference differential signal S is also 0 except for noise.
Therefore, if the threshold DC signal is set to the same value or a slightly larger value than the voltage value corresponding to the amplitude of the noise, it can be seen that the interference wave G has been received exceeding the original noise amount. The presence of the interference wave G (radio wave interference) in the region K can be determined.

Note that the converter circuit determines the amplitude represented by each DC signal using a comparator circuit, even if only the diode circuit is used to rectify both forward and reverse, without rectifying either the forward or reverse of the AC signal. It is possible to do. Further, the signal processing circuit 32 can process the amplitude of the output signal of the interference BPF 30 by converting the output signal of the interference BPF 30 by an A / D converter provided separately.
On the other hand, when attention is paid to the frequency of the interference differential signal S, when the interference wave G does not exist, the amplitude A _{2 of} the signal corresponding to the interference wave G becomes 0 except for noise, but this A ₂ = 0 is When substituting into the above equation (1), the interference difference signal S not only has an amplitude of 0, but also does not show a frequency as an AC signal, and becomes 0.
Therefore, in the interference difference signal S output from the mixer 27, the interference difference signal S is obtained by applying the Fourier transform formula shown in the above equation (8) to the value of the most frequently contained frequency component. Frequency spectrum (F1-F2) is obtained, and it is determined whether or not the frequency component indicating the peak of amplitude or energy in the spectrum exceeds the frequency component corresponding to the noise. The interference determination unit 6 may be configured to determine the presence of G (radio wave interference).

As another example of the interference wave determination process, the interference wave G can be determined without using the interference BPF 30 and the interference wave determination unit 31 shown in FIG.
In this case, the interference determination unit 6 is configured by the distance BPF 28 and the A / D converter 29.
Further, in this case, the basic signal M serving as a reference for the presence determination of the interference wave G is preferably a signal corresponding to the irradiation wave D in view of the frequency pass band of the distance BPF 28, but a signal corresponding to the distance BPF 28 (for example, As described above, when the signal having the highest and constant frequency immediately after irradiation of the irradiation wave D is used, the interference reference signal N may be used as described above.
The interference difference signal S obtained by mixing the signals corresponding to the basic signal M and the interference wave G is input to the distance BPF 28, and the output from the distance BPF 28 is converted by the A / D converter 29. Can be processed by the signal processing circuit 32.
As a result, the presence of the interference wave G can be determined based on whether or not the amplitude of the interference difference signal S has reached a certain level.

Here, further consideration will be given. When the interference reference signal N having a frequency within the frequency fluctuation range Δf “inside” or the signal corresponding to the irradiation wave D is the basic signal M, the difference input to the interference BPF 30. The signal V can be input to the distance BPF 28 at the same time.
That is, as shown by the pattern <6> in FIG. 3, if the object detection device 1 itself also calculates the distance to the object T by emitting the irradiation wave D, the distance from the object T to the distance BPF 28 is calculated. A difference signal V between a signal corresponding to the interference wave G including the reflected wave and the interference wave Z and a basic signal M (a signal corresponding to the irradiation wave D) is input.
Therefore, as will be described later in Examples 1 to 3 below, when the signal processing circuit 32 stops the irradiation of the irradiation wave D and only determines the interference wave G, and the interference wave G does not exist, By performing object detection processing by irradiating the irradiation wave D again, object detection is performed in an environment where the interference wave G does not exist, avoiding erroneously recognizing the interference wave G including the interference wave Z as the reflected wave R. You can also.

[Example 1]
Details of the first embodiment will be described based on the flowchart of the first embodiment of the present invention in FIG. 5 and the time chart of the first embodiment of the present invention in FIG.
Case <1> in FIG. 6 is a time chart when the interference wave G is received and there is an interference signal indicating the presence of the interference wave G.

According to the flowchart of FIG. 5, the signal processing circuit 32 periodically generates the sweep control signal. The interference signal is observed for the time determined in the interference wave determination process by the sweep control signal, and the presence or absence of the interference signal is determined. If it is determined that there is an interference signal, nothing is done and the next sweep control signal is awaited.
Case <2> in FIG. 6 is a time chart when the interference wave G is received and there is no interference signal.

According to the flowchart of FIG. 5, the signal processing circuit 32 periodically generates the sweep control signal. The interference signal is observed for the time determined in the interference wave determination process by the sweep control signal, and the presence or absence of the interference signal is determined.
When it is determined in the interference wave determination process that there is no interference signal, the object detection process is started, a modulation signal waveform is generated, the transmission switch 23 is closed (ON), and the irradiation wave D is irradiated from the transmission antenna.

When the object T exists in the detection region K, the receiving antenna 25 receives the reflected wave R of the object T, and digitally passes through the receiving amplifier 26, the mixer 27, the distance BPF 28, and the A / D converter 29. The signal is guided to the signal processing circuit 32 and frequency analysis processing is performed.
As a result of the frequency analysis, in the object detection process, the presence / absence of detection of the object T and the distance to the object T are determined, and as a result, an object detection signal is sent to the outside.

Then, the transmission switch 23 is opened (OFF), the irradiation of the irradiation wave D is stopped, and a series of operations for waiting for the next sweep control signal is repeated.
If it is determined in the above processing that there is an interference signal, the same effect can be obtained even if the interference wave determination processing is performed until it is determined that there is no interference wave G.

As an effect of the operation described above, it is confirmed that there is no interference wave G, and the irradiation wave D is radiated from the transmission antenna 24 by itself. Since R can be received, the object T can be detected without erroneous determination in the object detection process.
Moreover, since the irradiation wave D is irradiated from the transmitting antenna 24 only when necessary, the chance of inducing interference in the other object detection device 1 is reduced.

In other words, as shown in FIG. 5, the processing for calculating the distance to the object T while avoiding radio wave interference is started (step S0). Next, the sweep control signal (C3) is sent from the signal processing circuit 32. , C4) to the irradiating means 2 (step S1), and the irradiating means 2 outputs the interference reference signal N in a state where the irradiation of the irradiation wave D (radio wave D) is stopped for the time set in the interference wave determination process. Then, the presence determination of the interference wave G is started (step S2).
The presence of the interference wave G is determined (step S3). If it is determined that the interference wave G is present, the process returns to step S1 for issuing the sweep control signal. If it is determined that the interference wave G does not exist, the distance to the object T is actually measured. The process proceeds to the calculation process (step S4).
In step S4 for calculating the distance to the object T, the radio wave D is irradiated while being modulated, and from the beat difference signal B of the signal corresponding to the reflected wave R and the signal corresponding to the radio wave D to the object T through frequency analysis. The distance is calculated.
If the distance to the object T within the detection region K can be calculated, a signal indicating that the distance or the object T has been detected is output. Note that the reflection intensity, amplitude (the amplitude of the beat difference signal B) of the reflected wave R, and the like may be output. If the object T is not detected, the signal indicating that it has been detected is not output (step S4).
When the object detection process in step S4 is completed, a signal (C4) for stopping the irradiation of the radio wave D is output to the irradiation unit 2 (step S5).

Here, the object detection apparatus 1 may calculate the distance to the object T once for each irradiation of the radio wave D, and there are a plurality when the radio wave D is not irradiated in a period that is not necessary for the determination. Since the unnecessary interference due to the radio wave D from the object detection device 1 is eliminated and the probability of mutual interference can be further reduced, the time taken for each sweep is shorter than before, that is, the irradiation of the radio wave D of each object detection device 1 is stopped. The time is shortened, and as a result, the number of simultaneously usable object detection devices 1 is greatly increased.
Conventionally, the calculation speed of the signal processing means 5 may be slower than the time required for one irradiation of the radio wave D.

[Example 2]
Next, details of the second embodiment will be described with reference to the flowchart of the abnormal signal generation example of the present invention in FIG.
FIG. 7 is a flowchart showing an abnormality process based on the example of the flowchart for avoiding interference of the present invention shown in FIG. Assuming a situation in which an interference signal indicating that the interference wave G exists in the detection region K continues for a long time and the original object detection process cannot be performed. It is a flowchart figure which gave the measure which outputs an abnormal signal (holding excess signal H) from reservation excess part 7, and urges to perform setting etc. again.
Note that the hold excess signal H is set when the number of times the interference signal is output exceeds a predetermined value or the like, but based on other than the number of times the interference signal is output. The hold excess signal H may be output to the user of the device 1 or the manager of the plurality of devices 1 through output means such as a display, a lamp, or a buzzer.

For example, the object detection device 1 detects the interference wave G due to the influence of the device irradiated with the irradiation wave D emitted from another object detection device 1 or a similar radio wave irradiation device for a certain period of time, and detects the object. When the processing cannot be performed, the hold excess signal H may be output.
In this way, by performing a procedure for outputting the hold excess signal H, an irradiation wave D emitted from another object detection device 1 in the detection region K, an interference wave Z emitted from the object T in the detection region K, or the like. Even when the interference wave G continues to be generated, it is possible to recognize that the arrangement of the object detection devices 1 is inadequate, or to inform the detection region K that there is an object T that continues to emit the interference wave Z. It is possible to provide a more reliable device.

In other words, as shown in FIG. 7, in the second embodiment, from the start of the process until the object detection process is terminated and the irradiation of the radio wave D is stopped, the steps of the first embodiment are performed. It is the same as S0 to Step S5.
The difference between the second embodiment and the first embodiment is the presence or absence of processing (step S6) for outputting the excess hold signal H when the interference signal continues for a long time and the original object detection processing cannot be performed.

[Example 3]
Next, details of the third embodiment will be described based on the flowchart of the third embodiment of the present invention shown in FIG. 8 and the time chart of the third embodiment of the present invention shown in FIG.
First, referring to FIG. 9, in the case <3>, the object detection device 1a irradiates the irradiation wave D from the transmission antenna 24 after confirming that there is no interference signal based on the sweep control signal. 1b is a time chart when an interference signal is generated by the irradiation wave D irradiated from the object detection device 1a.
In this case <3>, the object detection device 1b has no past interference signal history (history of presence of the interference wave G) in the signal processing circuit 32 (interference prediction unit 8), and generates an interference signal. Therefore, the irradiation wave D is not irradiated from the transmission antenna 24.

  On the other hand, in the case <4> of FIG. 9, the object detection device 1a confirms that there is no interference signal based on the sweep control signal and irradiates the irradiation wave D from the transmission antenna. FIG. 11 is a time chart when the interference signal is generated by the irradiation wave D irradiated from the object detection device 1a, but the signal processing circuit 32 (interference prediction unit 8) has a history of past interference signals. The basic operation of Example 3 will be described.

In the third embodiment of the present invention, when there is an interference signal in the determination of the presence / absence of the interference signal after the interference wave determination processing in the flowchart of FIG. 8, the time when the interference signal is present is recorded, and the past reception history is recorded. It is characteristic that the signal processing circuit 32 includes an interference prediction unit 8 that predicts the interference wave G to be received next from the past interference signal history when the interference signal disappears.
If the operation of the interference prediction unit 8 is shown using FIG. 9, in case <3>, there is no history of interference signals in the interference prediction unit 8 of the object detection device 1b, and the object detection device 1b receives an irradiation wave D. However, the interference signal history (occurrence time, etc.) generated in this case <3> is stored in the interference prediction unit 8 of the object detection device 1b.
A predetermined time from the interference signal in the case <3> stored in the interference prediction unit 8 to the interference signal generated in the next case <4> is measured, and this predetermined time is also stored in the interference prediction unit 8. deep.
That is, in case <4>, it is predicted that the next interference signal will occur after this predetermined time (predicted interference time in case <4> in FIG. 9).
In this case <4>, the object detection device 1b determines that it has time to irradiate the irradiation wave D by the predicted interference time when the next interference signal is generated, and the next sweep control signal is Irradiation wave D is radiated without waiting for the time (timing) to occur.
As a result, the devices 1a and 1b contend for each other and calculate the distance at a shorter time interval than the time interval at which the object detection devices 1a and 1b generate the sweep control signal. At the same time, by predicting an irradiation wave D (interference wave G) emitted from another object detection device 1 installed in the same detection region K, more reliable object detection can be performed.

When the object detection device 1b determines that it does not have time to irradiate the irradiation wave D by the predicted interference time when the next interference signal is generated, as shown in the flowchart of FIG. A history is recorded as a time record with a signal and used for the next irradiation judgment.
Further, the processing of the third embodiment is higher than that of the second embodiment to supplement the basic operation, and can be omitted.

In other words, as shown in FIG. 9, in the third embodiment, from the start of the process until the presence determination of the interference wave G is performed, the steps S0 to S3 of the first and second embodiments It is the same.
In the third embodiment, when the interference signal continues for a long time and the original object detection process cannot be performed, the step S6 ′ for outputting the hold excess signal H is the same as the second embodiment. Step S6 is explained in detail.
Specifically, first, the time with the interference signal is recorded (step S61).
Next, it is determined whether or not the time when the interference signal is present exceeds a certain value (step S62). If the time is not exceeded, the process returns to step S3. The process proceeds to a process of outputting H (step S63), and the hold excess signal H is output in step S63.
The difference between the third embodiment and the first and second embodiments is in the presence or absence of the following steps S9 and S10. When it is determined in step S3 in the third embodiment that there is no interference signal, a time for the next occurrence of interference is predicted (step S7).
It is determined whether or not there is a time allowance for irradiation with respect to the interference prediction time (step S8). As a result, when it is determined that there is a time allowance, object detection is performed as in the first and second embodiments. Steps S4 and S5 are performed, and when it is determined that there is no time margin, the history is recorded as a time record with an interference signal, and the procedure proceeds to Step S61.

The present invention is not limited to the embodiment described above. Each configuration or overall structure, design shape, size, weight, and the like of the object detection device 1 can be changed as appropriate in accordance with the spirit of the present invention.
The object detection device 1 of the present invention is not limited to the FMCW radar device as long as the existence (presence / absence and distance to the device 1) of the object T in the detection region K can be determined, and other sensors using radio waves. It may be.
As described above, the reserve excess unit 7 and the interference prediction unit 8 may be provided in the signal processing unit 5, but the processing unit including the reserve excess unit 7 and the interference prediction unit 8 in addition to the signal processing unit 5. May be provided separately.

  The present invention can be applied to an application in which a plurality of object detection devices and similar radio wave irradiation devices are installed in the vicinity, and each device reliably detects detection of an object without causing interference. It is also useful when the distance calculation of an object is disturbed by radio waves from the object that has entered the detection area.

DESCRIPTION OF SYMBOLS 1 Object detection apparatus 2 Irradiation means 3 Reception means 4 Difference output means 5 Signal processing means 6 Interference determination part 7 Retention excess part 8 Interference prediction part 21 Modulation signal generator 22 Transmission amplifier 23 Transmission switch 24 Transmission antenna 25 Reception antenna 26 Reception amplifier 27 Mixer 28 Distance bandpass filter (distance BPF)
29 A / D converter 30 Interference bandpass filter (interference BPF)
31 Interference wave determination device 32 Signal processing circuit D Radio wave (irradiation wave)
K detection area T object M fundamental signal R reflected wave G interference wave V differential signal H hold excess signal Z interference wave N interference reference signal B beat differential signal S interference differential signal

The object detection device 1 according to the present invention irradiates the detection region K while frequency-modulating the radio wave D, and receives the reflected wave R reflected by the object T in the detection region K. An object detection device for calculating the distance to the object T at the time of stopping the irradiation of the radio wave D, and determining the presence of the interference wave G that hinders the distance calculation to the object T in the detection region K, and the interference wave G The signal processing means 5 that irradiates the radio wave D and calculates the distance to the object T when it is determined that the interference wave G exists, and suspends the irradiation stop of the radio wave D when it is determined that the interference wave G exists. An irradiating means 2 for irradiating the radio wave D to the detection region K, including an on-hold excess unit 7 for outputting an over-hold signal H when the irradiation stop of the radio wave D exceeds a predetermined time; and the reflected wave Receiving R or interference wave G At the same time, the signal processing means 5 has only one means 3 and one signal processing means 5, and the signal processing means 5 is only in the inside and asynchronous with the outside, and either the reflected wave R or the interference wave G is used. Based on a beat signal output by multiplying a signal corresponding to a received wave by a signal corresponding to the radio wave D, a distance calculation to the object T in the detection region K and an interference wave in the detection region K are performed. presence and determination of G, the first feature that you have the output of the hold excess signal H.
Note that the radio wave D in the present invention refers to an electromagnetic wave having a frequency of 3 THz or less, particularly a microwave having a frequency of 300 MHz to 3 THz, as in the general definition of radio waves. When the object detection apparatus 1 is installed as the moving body detection sensor of the specific low-power radio station described above, the radio wave D having a frequency of 24.05 GHz or more and 24.25 GHz or less is used.

A second feature of the object detection device 1 according to the present invention is that, in addition to the first feature, the signal processing means 5 is configured to generate an interference wave G in the detection region K based on the amplitude or frequency of the beat signal. Is in the presence of

A third feature of the object detection device 1 according to the present invention is that, in addition to the first or second feature, the signal processing unit 5 predicts a change in the interference wave G from the history of the presence determination of the interference wave G. And at least one of calculating the distance to the object T in the detection region K once for each irradiation of the radio wave D.

With these features, the object detection device 1 according to the present invention determines the interference wave G while stopping the irradiation of the radio wave D, and irradiates the radio wave D that is not necessary for the determination when the presence of the interference wave G is determined. By not doing so, it is possible to reduce the probability of interference by eliminating unnecessary interference due to radio waves D from a plurality of object detection devices 1, and to improve the accuracy of interference wave G determination.
At the same time, there is no restriction such as installation at a fixed distance from the reference reflector, and whether the source of the interference wave G is in the vicinity of the reference reflector as in Patent Document 1 or the like. Regardless, false detection of the interference wave G can be reduced.
In addition, the signal processing unit 5, to determine the presence of interference waves G in the irradiation stop in the detection area K of the radio wave D, the wave D to the object T by irradiated during the determination of the interference wave G is not present By suspending the irradiation stop of the radio wave D when it is determined that the interference wave G is present, the network construction at the installation site of the object detection device 1 and the registration setting to the constructed network become completely unnecessary. The irradiation timing of the radio wave D of each object detection device 1 is not constrained by the time required for synchronous communication between the devices 1.
Further, as in the case of constructing a network, there is no need for a time during which no radio wave is irradiated between the switching of each radar device, and if each object detection device 1 has a gap within a period in which no interference wave G exists. This is a state in which the user himself / herself radiates the radio wave D to calculate the distance, and the object detection is performed in a state of competing with each other, so that no time is detected when no object is detected.
When notifying by the hold excess signal H that the irradiation stop of the radio wave D has exceeded a predetermined time, the presence of the object detection apparatus 1 on which the radio wave D is held off is transmitted to the user of the apparatus 1, and this user However, it is possible to check the object T in the detection area K, or to cancel the hold by correcting the installation position of the object detection device 1, and to install a plurality of object detection devices 1 that have been installed with higher reliability. Can be provided.
In addition, by providing the signal processing means 5 with the retention excess section 7 for outputting the retention excess signal H, the object detection device is more effective than the case where the retention excess section 7 is separately provided outside the signal processing means 5. 1 can be made compact, and the signal processing means 5 and the retention excess portion 7 can be manufactured integrally, so that the production efficiency is improved.

With determining the presence of interference waves in the radio wave irradiation stop in the detection area, the interference wave does not exist by irradiating a radio wave to calculate the distance to the object at the time of determination, radio waves upon determination that interference waves exist By suspending the irradiation stop, it becomes possible to detect an object in an environment free from radio wave interference and prevent erroneous determination.

If there is a gap, in the case of each object detection device 1 that calculates the distance by competing with each other, a radio wave separated by 500 kHz exists in the same detection region K at the moment when the device 1 tries to irradiate the radio wave D. However, this radio wave is not recognized as an interference wave G that hinders calculation of the distance to the object T (no radio wave interference occurs), and a large number of object detection devices 1a, 1b, 1c, 1d, 1, 1, 1,... Continue to irradiate the irradiation wave D (radio wave D) continuously in 500 kHz increments, competing with each other if there is a gap.
For example, if the irradiation wave D of each device 1 decreases linearly by the frequency fluctuation width Δf during the sweep time ΔT as in the patterns <1> and <2> in FIG. The frequency immediately after irradiation of the radio wave D irradiated by the device 1d is the highest frequency (eg, 24.24 GHz) within the available frequency band (eg, width of 180 MHz), but the device 1d emits the radio wave D. Even at the “instant”, the radio waves D (eg: 24.2395 GHz, 24.2390 GHz) in the frequency band lower than the highest frequency (eg, 24.24 GHz) from the previous devices 1a, 1b, 1c. 24.2385 GHz) can be irradiated and can exist without affecting each other.
Therefore, even when this usable frequency band is estimated as low as 180 MHz with a margin of 10 MHz above and below of 24.25 GHz-24.05 GHz = 200 MHz, 180 MHz ÷ 500 kHz = 360 units, that is, in the frequency band of 180 MHz. The number of usable units can be calculated as 360 units.
Further, if 250 kHz, which is 10 times as much as 250 kHz corresponding to the reciprocation of the measurement range of the irradiation wave D, is further set as a margin, 180 MHz ÷ 2500 kHz = 72 units can be used simultaneously.

The present invention is not limited to the embodiment described above. Each configuration or overall structure, design shape, size, weight, and the like of the object detection device 1 can be changed as appropriate in accordance with the spirit of the present invention.
The object detection device 1 of the present invention is not limited to the FMCW radar device as long as the existence (presence / absence and distance to the device 1) of the object T in the detection region K can be determined, and other sensors using radio waves. It may be.
Pending excess portion 7, the interference prediction unit 8 may be provided in the signal processing unit 5 as described above, but outside the signal processing unit 5, is provided separately processing means having a interference prediction unit 8 It doesn't matter.

The present invention can be applied to an application in which a plurality of object detection devices and similar radio wave irradiation devices are installed in the vicinity, and each device reliably detects detection of an object without causing interference. Further, the radio wave from the entering the detection area the object is also useful in distance calculation to the object is impeded.

The present invention relates to an installation sensor provided with a plurality of object detection devices that irradiate a detection area with a radio wave, calculate a distance to an object by a reflected wave from an object that has entered the detection area, and determine the presence of the distance. More specifically, the object distance calculation is hindered by radio wave interference that occurs when radio waves are emitted from a plurality of object detection devices, or radio waves from an object that has entered the detection area. This relates to a sensor for installation to prevent in advance.

Therefore, the present invention calculates the distance to an object in an environment in which its own radio wave and other radio waves do not cause radio wave interference even if many object detection devices or multiple similar radio wave irradiation devices are installed in the detection area. An object of the present invention is to realize an installation sensor provided with a plurality of object detection devices for performing the above-described operation.

The installation sensor according to the present invention irradiates the detection region K while modulating the frequency of the radio wave D, and receives the reflected wave R reflected by the object T in the detection region K. a plurality of object detection apparatus which calculates a distance to an object T, a set up for a sensor installed at a position where the plurality of object detecting device detects an object T in one and the same the detection region K, the object each sensing device, the irradiation means 2 freely radiated to the radio wave D the detection region K, a receiving unit 3 for receiving the reflected wave R or interference wave G, the detection area K when irradiation stop of the radio wave D The presence of an interference wave G that hinders the calculation of the distance to the object T at the same time is determined, and when it is determined that the interference wave G does not exist, the radio wave D is irradiated to calculate the distance to the object T, and the interference wave If G exists And signal processing means 5 for holding the irradiation stop of the radio wave D when was boss has one, the signal processing means 5 in each of the object detecting apparatus, the inside only and without communication with the outside in and without communication between the plurality of object detecting device, it is outputted by multiplying the signal corresponding signal corresponding to the waves received at one of the reflected wave R or interference wave G with the electric wave D Based on the beat signal, the distance to the object T in the detection area K is calculated, the presence of the interference wave G in the detection area K is determined, and when the irradiation stop of the radio wave D exceeds a predetermined time Is provided with a hold excess unit 7 for outputting a hold excess signal H to notify the position deficiency between the plurality of object detection devices, and the signal processing means 5 in each of the object detection devices is an irradiation hand in the object detection device. 2 irradiates the detection region K with the radio wave D while linearly reducing the frequency of the radio wave D by a frequency fluctuation width Δf, and determines whether the interference wave G is present or not by a signal corresponding to the interference wave G. And a signal corresponding to the radio wave D based on a beat signal output by multiplying the signal having the same value as the highest frequency immediately after irradiation within the frequency fluctuation range Δf of the radio wave D with a constant frequency. The signal processing means 5 in each of the object detection devices executes first to sixth steps S1 to S6 for calculating the distance to the object T, determining the presence of the interference wave G, and outputting the hold excess signal H. The first step S1 is a step in which the signal processing means 5 outputs a sweep control signal for stopping the irradiation means 2 from irradiating the radio wave D, and the process proceeds to the second step S2. In the second step S2, the signal processing means 5 determines the presence of the interference wave G in a state where the irradiation means 2 stops the irradiation of the radio wave D, and the signal processing means 5 determines that the interference wave G exists. In the case where an interference signal indicating the presence of the interference wave G in the detection region K is output, the process proceeds to the third step S3, and the signal processing means 5 determines that the interference wave G does not exist. Similarly, the process proceeds to the third step S3 without outputting an interference signal, and the third step S3 proceeds to the sixth step S6 if there is an interference signal output in the second step S2. If there is no interference signal output in the second step S2, the process proceeds to the fourth step S4. The fourth step S4 is performed while the irradiation means 2 irradiates the radio wave D once. The distance to the object T The signal processing means 5 calculates once and moves to the fifth step S5. In the fifth step S5, after the distance calculation to the object T is calculated, the signal processing means 5 sends the irradiation means 2 to the irradiation means 2. The step of stopping the irradiation of the radio wave D and proceeding to the first step S1, and the sixth step S6 is a step of stopping the irradiation of the radio wave D if the interference signal has been output a predetermined number of times or more. as exceeded time, the signal processing unit 5 is the first feature step der Rukoto move by outputting the hold excess signal H to the first step S1.
Note that the radio wave D in the present invention refers to an electromagnetic wave having a frequency of 3 THz or less, particularly a microwave having a frequency of 300 MHz to 3 THz, as in the general definition of radio waves. For installing the object detecting device 1 as moving body detection sensors specified low power radio station as described above, so that the frequency to use 24.25GHz following wave D above 24.05GHz.

A second feature of the installation sensor according to the present invention is that, in addition to the first feature, the signal processing means 5 in each of the object detection devices is configured to detect the interference wave next from the history of the presence determination of the interference wave G. The interference prediction unit 8 for obtaining a predicted interference time at which G is predicted to be generated is provided, and when it is determined that the interference wave G exists, the radio wave D is emitted before the predicted interference time by the interference prediction unit 8 determining whether the time, when it is determined that the time for the irradiation is present, then without waiting the time when the sweep control signal is generated, Ru is irradiated with radio waves D to the irradiation unit 2 in the object detecting device In the point.

Due to these characteristics, the installation sensor including a plurality of object detection devices 1 according to the present invention determines the interference wave G while stopping the irradiation of the radio wave D, and determines when the presence of the interference wave G is present. By not irradiating unnecessary radio waves D, unnecessary interference due to radio waves D from a plurality of object detection devices 1 can be eliminated and the probability of interference can be reduced, and the accuracy of interference wave G determination can be improved.
At the same time, there is no restriction such as installation at a fixed distance from the reference reflector, and whether the source of the interference wave G is in the vicinity of the reference reflector as in Patent Document 1 or the like. Regardless, false detection of the interference wave G can be reduced.
In addition, the signal processing means 5 determines the presence of the interference wave G in the detection region K when the irradiation of the radio wave D is stopped, and irradiates the radio wave D to the object T when determining that the interference wave G does not exist. By suspending the irradiation stop of the radio wave D when it is determined that the interference wave G is present, the network construction at the installation site of the object detection device 1 and the registration setting to the constructed network become completely unnecessary. The irradiation timing of the radio wave D of each object detection device 1 is not constrained by the time required for synchronous communication between the devices 1.
Further, as in the case of constructing a network, there is no need for a time during which no radio wave is irradiated between the switching of each radar device, and if each object detection device 1 has a gap within a period in which no interference wave G exists. This is a state in which the user himself / herself radiates the radio wave D to calculate the distance, and the object detection is performed in a state of competing with each other, so that no time is detected when no object is detected.
When notifying by the hold excess signal H that the irradiation stop of the radio wave D has exceeded a predetermined time, the presence of the object detection apparatus 1 on which the radio wave D is held off is transmitted to the user of the apparatus 1, and this user However, it is possible to check the object T in the detection area K, or to cancel the hold by correcting the installation position of the object detection device 1, and to install a plurality of object detection devices 1 that have been installed with higher reliability. Can be provided.
In addition, by providing the signal processing means 5 with the retention excess section 7 for outputting the retention excess signal H, the object detection device is more effective than the case where the retention excess section 7 is separately provided outside the signal processing means 5. 1 can be made compact, and the signal processing means 5 and the retention excess portion 7 can be manufactured integrally, so that the production efficiency is improved.

Incidentally, if the number of devices that can be used simultaneously is illustrated and compared, in the case of a conventional FMCW radar device, in order not to interfere with each other, the frequency band of 24.05 GHz to 24.25 GHz is divided (substantially about two categories), Even when the horizontal polarization and the vertical polarization are used for each division, there are at most four divisions (that is, the maximum number of simultaneous use is four).
However, in the installation sensor provided with a plurality of object detection devices 1 according to the present invention, assuming that the measurement distance to the object T is 200 m, the frequency of the beat signal of the reflected wave R and the radio wave D is as described later. If the frequency of the beat signal is 500 kHz or more for each object detection device 1 with a margin of twice this, the frequency band that can be used is 24. Even if it takes a margin of 10 MHz up and down and 25 MHz-24.05 GHz = 200 MHz and estimates it as small as 180 MHz, 180 MHz ÷ 500 kHz = 360 units, that is, 360 units can be calculated as 360 units, and simultaneous use The number of possible units can be greatly increased from four.

An embodiment of the present invention will be described in detail with reference to FIGS.
<Usage environment, overall configuration>
Figure 1 is a block diagram showing the configuration of the FMCW radar device which is an example of an object body detecting device 1 is a block diagram generally are well utilized.
Object body sensing device 1 may, for example, as shown in FIG. 10, the environment in which the predetermined detection region K in which a plurality of object apparatuses 1a~1d is installed, taking a certain object detection apparatus 1a, radio interference may occur ( It can also be used in environments in which the radio waves Db and Dc from the other object detection devices 1b and 1c and the reflected wave Rd reflected from the object T by the radio wave Dd from the other object detection device 1d can be incident as an interference wave Z).
The object detection apparatus 1 includes an irradiation unit 2 that irradiates a detection region K with a radio wave D (hereinafter referred to as “irradiation wave D”), a reception unit 3 that receives a reflected wave R or an interference wave G, and a reflected wave R or interference. Difference output means 4 for outputting a difference signal V between the wave G and the irradiation wave D and signal processing means 5 for calculating a distance to the object T based on the difference signal V are provided.

The present invention is not limited to the embodiment described above. Each configuration or overall structure, design shape, size, weight, and the like of the installation sensor can be appropriately changed in accordance with the spirit of the present invention .
Pending excess portion 7, the interference prediction unit 8 may be provided in the signal processing unit 5 as described above, but outside the signal processing unit 5, is separately provided with a processing unit with an interference prediction unit 8 It doesn't matter.

Claims (3)

By irradiating the detection area (K) while frequency-modulating the radio wave (D) and receiving the reflected wave (R) reflected by the object (T) in the detection area (K), the detection area (K) ) For detecting the distance of the object (T) in
The presence of an interference wave (G) that hinders calculation of the distance to the object (T) in the detection region (K) when the irradiation of the radio wave (D) is stopped is determined, and it is determined that the interference wave (G) does not exist. Signal processing means (5) that irradiates the radio wave (D), calculates the distance of the object (T), and suspends the radio wave (D) irradiation stop when it is determined that the interference wave (G) exists. )
An object detection apparatus comprising: an overholding unit (7) that outputs an overholding signal (H) when the irradiation stop of the radio wave (D) exceeds a predetermined time. By irradiating the detection area (K) while frequency-modulating the radio wave (D) and receiving the reflected wave (R) reflected by the object (T) in the detection area (K), the detection area (K) ) For detecting the distance of the object (T) in
The presence of an interference wave (G) that hinders calculation of the distance to the object (T) in the detection region (K) when the irradiation of the radio wave (D) is stopped is determined, and it is determined that the interference wave (G) does not exist. Signal processing means (5) that irradiates the radio wave (D), calculates the distance of the object (T), and suspends the radio wave (D) irradiation stop when it is determined that the interference wave (G) exists. )
An object detection apparatus comprising: an interference prediction unit (8) that predicts a change in the interference wave (G) from a history of presence determination of the interference wave (G). By irradiating the detection area (K) while frequency-modulating the radio wave (D) and receiving the reflected wave (R) reflected by the object (T) in the detection area (K), the detection area (K) ) For detecting the distance of the object (T) in
The presence of an interference wave (G) that hinders calculation of the distance to the object (T) in the detection region (K) when the irradiation of the radio wave (D) is stopped is determined, and it is determined that the interference wave (G) does not exist. Signal processing means (5) that irradiates the radio wave (D), calculates the distance of the object (T), and suspends the radio wave (D) irradiation stop when it is determined that the interference wave (G) exists. )But,
An object detection apparatus that calculates a distance to an object (T) in the detection region (K) once for each irradiation of the radio wave (D).