JP4797951B2 - Object detection device - Google Patents

Description

  The present invention relates to an object detection device that detects an object embedded in the ground or a structure or an object present on the back side of the structure by electromagnetic waves.

  Conventionally, as a technique for detecting an object embedded in the ground or a structure (for example, a buried pipe) with an electromagnetic wave, an antenna unit that transmits and receives pulsed electromagnetic waves is used as a reference surface made of the ground surface or the structure surface. It is possible to detect an object by moving it to a plurality of antenna positions along the line, receiving the electromagnetic wave transmitted from the antenna unit and reflected by the object at each antenna position, and converting the electromagnetic wave into a received signal that is an electric signal. It is known (see, for example, Patent Document 1).

  By the way, the received signal received by the antenna unit in this type of object detection includes not only the reflected wave component corresponding to the electromagnetic wave reflected by the object but also the unnecessary wave component such as the electromagnetic wave reflected by the reference plane. It is. The unnecessary wave component is normally common to each antenna position, and takes a steady value unless the measurement environment changes greatly.

  Here, the intensity of the received signal received at each antenna position is set as intensity data at each sampling interval of a predetermined interval, and a set of the intensity data for each antenna position is stored in the storage unit as a data string for each position, and a plurality of antennas are stored. It is considered that a set of a plurality of sampling timings of the average value is assumed as an unnecessary wave component by calculating an average value of intensity data at the same sampling timing at the position. In this case, the reflected wave component is calculated by subtracting the calculated unnecessary wave component from the position-specific data string at each antenna position.

In the invention described in Patent Document 1, the average value of the intensity data at all antenna positions is not set as an unnecessary wave component, but the intensity at the antenna position to be calculated of the reflected wave component and the plurality of antenna positions before and after the antenna position. The average value of the data is an unnecessary wave component.
JP-A-10-132950 (page 4-5)

  However, in the above-described conventional technique, since the data stream for each position includes not only the unwanted wave component but also the reflected wave component, the reflected wave is included in the unwanted wave component consisting of the average value of the intensity data of the data stream for each position. If the unnecessary wave component is subtracted from the position-specific data string, the intensity of the reflected wave component after the subtraction may be attenuated more than the actual reflected wave component. In particular, in the invention described in Patent Document 1, since the number of intensity data when extracting unnecessary wave components is small, the ratio of the reflected wave component to the extracted unnecessary wave components is increased, and the position-specific data string is used. When the unnecessary wave component is subtracted, the intensity of the reflected wave component after the subtraction is greatly attenuated.

  As a result, the intensity of the reflected wave component calculated for objects that exist in a medium with a high electromagnetic wave attenuation rate, objects that are far from the reference plane, and objects that have a low electromagnetic wave reflectance. May become too small to detect the object.

  The present invention has been made in view of the above-described reasons, and an object thereof is to provide an object detection apparatus that can suppress the attenuation of the intensity of the calculated reflected wave component to be smaller than that of the conventional configuration.

  In the first aspect of the invention, electromagnetic waves are intermittently transmitted from the antenna portion toward the reference plane at a plurality of antenna positions along the reference plane set in the detection area, and reflected by an object existing in the back of the reference plane. An object detection device that detects an object by receiving an electromagnetic wave received by an antenna unit and converting the received electromagnetic wave into a reception signal that is an electric signal, and the intensity of the reception signal received at each antenna position is determined at a sampling interval of a predetermined interval. And sampling means for storing a set of intensity data for each antenna position in the storage unit as a data string for each position, and unnecessary extraction of unnecessary wave components included in the data string for each position at each antenna position Corresponding to the electromagnetic wave reflected by the object by subtracting the unnecessary wave component from the wave extraction means and the position-specific data string at each antenna position. Unnecessary wave removing means for obtaining reflected wave components and detection for detecting the state of an object based on the intensity of reflected wave components at a plurality of antenna positions and the elapsed time from when an electromagnetic wave is transmitted until the reflected wave component is received And the unnecessary wave extracting means obtains a representative value of the intensity data at the same sampling timing for the data string for each position stored in the storage unit, and temporarily collects a set of the representative values for a plurality of sampling timings. Temporary unnecessary wave extracting means for extracting as a wave component, temporary unnecessary wave removing means for obtaining a temporary reflected wave component by subtracting the temporary unnecessary wave component from each position data string at each antenna position, and stored in the storage unit For each position of the antenna position within a predetermined range including the antenna position where the intensity of the electromagnetic wave reflected by the object in the temporarily reflected wave component is the maximum. Data string classification means for classifying the data string into a strong data string that is a data string and a weak data string other than the strong data string, and obtaining a representative value of the intensity data for each of the same sampling timing with respect to the weak data string. A set of values corresponding to a plurality of sampling timings is used as the unnecessary wave component.

  According to this configuration, the unnecessary wave extracting unit obtains the representative value of the intensity data for each of the same sampling timing with respect to only the weak data string of the data string for each position stored in the storage unit, and a plurality of the representative values are obtained. Therefore, the reflected wave component in the strong data string is not included in the unnecessary wave component extracted by the unnecessary wave extracting means. Here, the strong data string is a data string for each position of the antenna position within a predetermined range including the antenna position where the intensity of the electromagnetic wave reflected by the object in the provisional reflected wave component is maximum. If the reflected wave component is not included in the unnecessary wave component, even if the unnecessary wave component is subtracted from the position-specific data string, the intensity of the reflected wave component after the subtraction is attenuated more than the actual reflected wave component. Absent. In other words, the configuration of claim 1 has an advantage that the attenuation of the intensity of the calculated reflected wave component can be suppressed smaller than that of the conventional configuration. The representative value here means an average value, a median value, a mode value, or the like. In addition, the detection means, as the state of the object, for example, the presence or absence of the object and the distance to the object based on the intensity of the reflected wave component and the elapsed time from when the electromagnetic wave is transmitted until the reflected wave component is received In addition, the size, shape, and material of the object, and the characteristics of the propagation medium (wall material, etc.) existing between the object detection device and the object are detected.

  According to a second aspect of the present invention, in the first aspect of the invention, the data string classification unit detects intensity data that is the maximum value of the provisional reflected wave component at each antenna position as maximum data, and the maximum data is detected. Among the antenna positions that have the maximum intensity when arranged in the same order as the antenna positions, the antenna position whose maximum data is greater than or equal to a predetermined threshold is set as the reference position, and the reference position and the position of the plurality of antenna positions before and after the reference position The position-specific data string at the antenna position where the maximum data is equal to or greater than the value obtained by multiplying the maximum data at the reference position by a predetermined value less than 1 is the strong data string.

  According to this configuration, since the data string for each position is classified into the strong data string and the weak data string based on the magnitude of the maximum data intensity at each antenna position, the data for each position can be obtained by relatively simple calculation processing. Columns can be classified.

  According to a third aspect of the present invention, in the first aspect of the invention, the data string classification unit detects intensity data that is the maximum value of the provisional reflected wave component at each antenna position as maximum data, and the maximum data is detected. Among the antenna positions where the intensity becomes maximum when arranged in the same order as the antenna positions, the antenna position where the maximum data is equal to or more than a predetermined threshold is set as the reference position, and a preset number before and after the reference position and the reference position The position-specific data string at the antenna position is the strong data string.

  According to this configuration, since the data string for each position is classified into the strong data string and the weak data string based on the magnitude of the maximum data intensity at each antenna position, the data for each position can be obtained by relatively simple calculation processing. Columns can be classified. In addition, since the number of data strings for each position, which is a strong data string, is fixed with respect to one reference position, the antenna positions before and after the reference position may be measured at the antenna positions before and after the measurement error due to the malfunction of the object detection device. Even if an abnormal value extremely smaller than the maximum data is detected, it is possible to remove the influence of the abnormal value by making the data string for each position of the antenna position where the abnormal value is detected also a strong data string.

  According to a fourth aspect of the present invention, in the first aspect of the invention, the data string classification unit detects intensity data that is the maximum value of the provisional reflected wave component at each antenna position as maximum data, and the maximum data is The antenna position where the maximum data is equal to or greater than a predetermined threshold among the antenna positions having the maximum intensity when arranged in the same order as the antenna position is set as a reference position, and the data string for each position at the reference position is the strong data string. It is characterized by.

  According to this configuration, since the data string for each position is classified into the strong data string and the weak data string based on the magnitude of the maximum data intensity at each antenna position, the data for each position can be obtained by relatively simple calculation processing. Columns can be classified. In addition, since the data string for each position at the reference position is a strong data string, it is not necessary to perform a calculation process for determining the range of the strong data string after obtaining the reference position, and the calculation process can be further simplified.

  According to a fifth aspect of the present invention, in the first aspect of the invention, the data string classification unit detects intensity data that is a maximum value of the provisional reflected wave component at each antenna position as maximum data, and the plurality of antennas. Among the positions, the position-specific data string at the antenna position where the maximum data is equal to or greater than a predetermined threshold is the intensity data string.

  According to this configuration, since the data string for each position is classified into the strong data string and the weak data string based on the magnitude of the maximum data intensity at each antenna position, the data for each position can be obtained by relatively simple calculation processing. Columns can be classified. In addition, since the data string for each position at the antenna position where the maximum data is equal to or greater than the predetermined threshold is a strong data string, it is not necessary to perform a calculation process for determining the range of the strong data string, and the calculation process can be further simplified.

  According to a sixth aspect of the present invention, in the first aspect of the invention, the data string classification unit detects intensity data that is the maximum value of the provisional reflected wave component at each antenna position as maximum data, and an electromagnetic wave is transmitted. The antenna position where the maximum data is equal to or greater than a predetermined threshold among the antenna positions that are the minimum of the elapsed time when the elapsed time from when the maximum data is received is arranged in the same order as the antenna position And the position-specific data string at the antenna position where the maximum data is not less than a value obtained by multiplying the maximum data at the reference position by a predetermined value less than 1 among the reference position and the plurality of antenna positions before and after the reference position. It is characterized by a strong data string.

  According to this configuration, the data string for each position is classified into the strong data string and the weak data string based on the elapsed time from when the electromagnetic wave at each antenna position is transmitted until the maximum data is received. Even when noise is superimposed on an electromagnetic wave reflected by an object and the intensity of each maximum data does not take an accurate value, the data for each position can be classified.

  According to a seventh aspect of the invention, in the first aspect of the invention, the data string classification unit detects intensity data that is the maximum value of the provisional reflected wave component at each antenna position as maximum data, and electromagnetic waves are transmitted. The antenna position where the maximum data is equal to or greater than a predetermined threshold among the antenna positions that are the minimum of the elapsed time when the elapsed time from when the maximum data is received is arranged in the same order as the antenna position The position data string at each position at a predetermined number of antenna positions before and after the reference position is set as the strong data string.

  According to this configuration, the data string for each position is classified into the strong data string and the weak data string based on the elapsed time from when the electromagnetic wave at each antenna position is transmitted until the maximum data is received. Even when noise is superimposed on an electromagnetic wave reflected by an object and the intensity of each maximum data does not take an accurate value, the data for each position can be classified. In addition, since the number of data strings for each position, which is a strong data string, is fixed with respect to one reference position, the antenna positions before and after the reference position may be measured at the antenna positions before and after the measurement error due to the malfunction of the object detection device. Even if an abnormal value extremely smaller than the maximum data is detected, it is possible to remove the influence of the abnormal value by making the data string for each position of the antenna position where the abnormal value is detected also a strong data string.

  According to an eighth aspect of the present invention, in the first aspect of the invention, the data string classification unit detects intensity data that is the maximum value of the provisional reflected wave component at each antenna position as maximum data, and an electromagnetic wave is transmitted. The antenna position where the maximum data is equal to or greater than a predetermined threshold among the antenna positions that are the minimum of the elapsed time when the elapsed time from when the maximum data is received is arranged in the same order as the antenna position It is a position, and the data string for each position at the reference position is the strong data string.

  According to this configuration, the data string for each position is classified into the strong data string and the weak data string based on the elapsed time from when the electromagnetic wave at each antenna position is transmitted until the maximum data is received. Even when noise is superimposed on an electromagnetic wave reflected by an object and the intensity of each maximum data does not take an accurate value, the data for each position can be classified. In addition, since the data string for each position at the reference position is a strong data string, it is not necessary to perform a calculation process for determining the range of the strong data string after obtaining the reference position, and the calculation process can be simplified.

  A ninth aspect of the present invention provides the method according to any one of the second to eighth aspects, wherein the threshold value is smaller as the elapsed time from when the electromagnetic wave is transmitted until the maximum data is received is longer. It is characterized by being associated with the elapsed time.

  According to this configuration, the threshold value becomes smaller as the elapsed time from when the electromagnetic wave is transmitted until the maximum data is received becomes longer, so that the threshold value becomes smaller as the distance from the reference surface to the object increases. Here, in general, as the distance from the reference plane to the object increases, the maximum data in the position-specific data string attenuates and decreases. That is, in the configuration of claim 9, when the distance from the reference plane to the object is relatively large, the strong data string and the weak data string are surely classified even if the maximum data in the position-specific data string is reduced. can do.

  According to a tenth aspect of the present invention, in any one of the second to eighth aspects, the threshold value is set to a predetermined value in advance.

  According to this configuration, the arithmetic processing for determining the threshold value is unnecessary, and therefore the arithmetic processing can be simplified.

  The invention of claim 11 is the invention according to any one of claims 1 to 10, wherein at least one of the provisional unnecessary wave extraction means and the unnecessary wave extraction means includes a plurality of the sampling times at the same sampling timing. The intensity range in which the intensity data of the antenna position is distributed is divided into intensity intervals of a certain intensity width, and the average value of the intensity data obtained for the intensity interval where the number of intensity data is the largest is the representative value. It is characterized by.

  According to this configuration, at least one of the provisional unnecessary wave extracting unit and the unnecessary wave extracting unit uses the average value of the intensity data obtained for the intensity interval in which the number of intensity data is the largest as the representative value. In general, the intensity data is distributed in the direction of the intensity axis with respect to the temporary unnecessary wave component and the unnecessary wave component. As compared with the case where the unnecessary wave component is obtained, the temporary unnecessary wave component and the unnecessary wave component can be accurately calculated without being affected by the bias of the distribution of the intensity data. Therefore, the reflected wave component can be obtained with high accuracy, and the detection accuracy of the state of the object is improved.

  According to a twelfth aspect of the present invention, in any one of the first to tenth aspects of the present invention, at least one of the temporary unnecessary wave extracting unit and the unnecessary wave extracting unit is a plurality of times determined at the same sampling timing. The median value of the intensity data at the antenna position is set as the representative value.

  According to this configuration, at least one of the temporary unnecessary wave extraction unit and the unnecessary wave extraction unit uses the median value of the intensity data of the plurality of antenna positions obtained at the same sampling timing as a representative value. In general, the intensity data is distributed in the direction of the intensity axis with respect to the temporary unnecessary wave component and the unnecessary wave component. However, in the configuration of claim 12, the temporary unnecessary wave component is calculated from the average value of all intensity data at each sampling timing. As compared with the case where the unnecessary wave component is obtained, the temporary unnecessary wave component and the unnecessary wave component can be accurately calculated without being affected by the bias of the distribution of the intensity data. Therefore, the reflected wave component can be obtained with high accuracy, and the detection accuracy of the state of the object is improved.

  According to a thirteenth aspect of the present invention, in any one of the first to tenth aspects of the present invention, at least one of the provisional unnecessary wave extracting means and the unnecessary wave extracting means is a plurality of times determined at the same sampling timing. An average value of intensity data at the antenna position is set as the representative value.

  According to this configuration, since at least one of the temporary unnecessary wave extraction unit and the unnecessary wave extraction unit uses the average value of the intensity data of a plurality of antenna positions obtained at the same sampling timing as a representative value, it is relatively simple. The temporary unnecessary wave component and the unnecessary wave component can be obtained by simple calculation processing.

  According to the present invention, the unnecessary wave extracting unit obtains a representative value of the intensity data for each of the same sampling timing with respect to only the weak data string among the position-specific data strings stored in the storage unit, and performs a plurality of samplings of the representative value. Since the set for the timing is used as the unnecessary wave component, the reflected wave component in the strong data string is not included in the unnecessary wave component extracted by the unnecessary wave extracting unit. Here, the strong data string is a data string for each position of the antenna position within a predetermined range including the antenna position where the intensity of the electromagnetic wave reflected by the object in the provisional reflected wave component is maximum. If the reflected wave component is not included in the unnecessary wave component, even if the unnecessary wave component is subtracted from the position-specific data string, the intensity of the reflected wave component after the subtraction is attenuated more than the actual reflected wave component. Absent. That is, in the configuration of claim 1, the attenuation of the calculated reflected wave component intensity can be suppressed to be smaller than that of the conventional configuration. As a result, there is an advantage that an object can be detected even with respect to an object existing in a medium with a high electromagnetic wave attenuation rate, an object located far from the reference plane, or an object with a low electromagnetic wave reflectance. is there.

(Embodiment 1)
The object detection device of the present embodiment includes an antenna unit that receives a transmission signal that is an electrical signal with one antenna and transmits an electromagnetic wave, and receives the electromagnetic wave with the antenna and converts it into a reception signal that is an electrical signal. As shown in FIG. 2, electromagnetic waves are intermittently transmitted from the antenna unit 1 toward the reference surface S at a plurality of antenna positions X1 to Xn (here, n locations) along the reference surface S composed of the ground surface or the structure surface. The object B is detected by receiving the electromagnetic wave reflected by the object B existing behind the reference plane S by the antenna unit 1.

  As shown in FIG. 1A, the object detection device generates and outputs a timing signal that determines a reception period after transmission of the transmission signal and the electromagnetic wave, and is output from the signal generation unit 2. A first signal processing unit 3 that performs signal processing on the transmitted signal to transmit a pulsed electromagnetic wave from the antenna unit 1, and receives a reception signal from the antenna unit 1 during the reception period at each antenna position X1 to Xn. And a second signal processing unit 4 that processes each received signal and detects the object B. Furthermore, the memory | storage part 5 which memorize | stores the various data used for the signal processing in the 2nd signal processing part 4, the output part 6 which outputs the detection result in the 2nd signal processing part 4, etc., the signal generation part 2, and Provided are a control unit 7 that controls the signal processing method (including the output contents of the output unit 6) of each signal processing unit 3 and 4, and an input unit 8 that is operated to give various instructions to the control unit 7. It has been.

  Here, the signal generation unit 2 generates a transmission signal and a timing signal based on the control signal from the control unit 7, gives the transmission signal to the first signal processing unit 3, and sends the timing signal to the second signal processing unit. Give to 4. The first signal processing unit 3 performs processing such as amplification on the input transmission signal and transmits electromagnetic waves from the antenna unit 1.

  As shown in FIG. 1B, the second signal processing unit 4 amplifies the reception signal from the antenna unit 1 and the intensity of the reception signal amplified by the amplification unit 9 in the reception period. A / D conversion unit 10 (sampling means) that converts digital intensity data at each sampling timing and stores it in the storage unit 5, and an operation for detecting the object B using the intensity data stored in the storage unit 5 Part 11. In the storage unit 5, each antenna position X1 to Xn and each sampling timing are paired and stored in association with each intensity data, and the intensity data substantially includes the antenna positions X1 to Xn and the sampling timing. Is formed in a two-dimensionally arranged data map. Here, a set for each antenna position X1 to Xn of intensity data in the storage unit 5 is defined as a data string for each position.

  The calculation unit 11 includes an unnecessary wave extraction unit 12 that obtains an unnecessary wave component common to the antenna positions X1 to Xn, and an unnecessary wave removal unit that obtains a reflected wave component by subtracting the unnecessary wave component from the position-specific data string. 13 and detection means 14 for detecting the state of the object B based on the intensity of the reflected wave component at a plurality of antenna positions X1 to Xn.

  The unnecessary wave extracting means 12 of the present embodiment obtains representative values of intensity data at the same sampling timing with respect to the data sequence for each position stored in the storage unit 5, and temporarily sets a set of representative values for a plurality of sampling timings. Temporary unnecessary wave extracting means 16 for extracting as unnecessary wave components, temporary unnecessary wave removing means 17 for obtaining temporary reflected wave components by subtracting the temporary unnecessary wave components from the position-specific data strings at the respective antenna positions X1 to Xn, The position-specific data string stored in the storage unit 5 includes the antenna positions X1 to Xn within a predetermined range including the antenna positions X1 to Xn at which the intensity of the electromagnetic wave reflected by the object B in the temporarily reflected wave component is maximized. Data string classification means 18 for classifying into a strong data string that is a data string for each position and a weak data string other than the strong data string. The unnecessary wave extraction unit 12 obtains a representative value of intensity data for each sampling timing that is the same for the weak data string, and outputs a set of the representative values for a plurality of sampling timings as unnecessary wave components.

  Hereinafter, the operation of the object detection apparatus of the present embodiment will be described with reference to the flowchart of FIG. Here, a case will be described in which signals are received at a plurality of (n) antenna positions X1 to Xn as shown in FIG. Further, each antenna position X1 to Xn is set such that A1 is a data string for each position corresponding to the received signal received at the antenna position X1, and A2 is a data string for each position corresponding to the received signal received at the antenna position X2. The position-specific data strings corresponding to the received signals received in step 1 are referred to as position-specific data strings A1 to An, respectively. FIGS. 2 and 3 show the data string A3 for each position when the antenna unit 1 is at the antenna position X3. Hereinafter, the elapsed time from the time of electromagnetic wave transmission is referred to as propagation time T. In FIG. 3, the horizontal axis is the propagation time T, and the vertical axis is the intensity.

  Step S1 in FIG. 4 is initialization, and various parameters set here (i = 0, setting of a noise component calculation method, setting of classification criteria for the data sequences A1 to An for each position, etc.) are determined in advance. It may be a value captured by the input unit 8.

  Subsequently, in steps S <b> 2 and S <b> 3, the position-specific data strings A <b> 1 to An of the antenna positions X <b> 1 to Xn are individually taken into the storage unit 5. The data strings A1 to An for each position are fetched until the necessary number of data strings (that is, the number n of antenna positions X1 to Xn) is reached (S4, S5). Here, each time the new position-specific data strings A1 to An are captured, the already-acquired position-specific data strings A1 to An are shifted one by one (S2). As a result, after the position-specific data strings A1 to An are once fetched by the number n of data strings and the analysis result is obtained by the detection means 14 described later, each time one new position-specific data string A1 to An is fetched, Only the data strings A1 to An for each position are updated, and the analysis by the detection means 14 can be newly performed. That is, the newest position-specific data strings A1 to An can be replaced with the oldest position-specific data strings A1 to An. Similarly, other signal processing methods that can replace the old and new position-specific data strings A1 to An may be used for capturing the position-specific data strings A1 to An.

  Here, the data strings A1 to An for each position are each represented by a set of a plurality of intensity data by being sampled by the A / D converter 10. Here, by setting the time interval of the sampling timing to Δt [s] as shown in FIG. 3B, each position data string A1 to An is represented by a total of m intensity data (elements). . That is, the data string for each position A1 = [intensity data A1 (1), intensity data A1 (2),..., Intensity data A1 (m)], the data string for each position A2 = [intensity data A2 (1), intensity Data A2 (2),..., Intensity data A2 (m)],..., Position-specific data string An = [intensity data An (1), intensity data An (2),. (M)].

  The intensity data is also stored at the same sampling timing (same propagation time T) in the storage unit 5, and constitutes hourly data strings t1 to tm, respectively. That is, a set of intensity data at the first sampling timing in the received data sequences A1 to An for each position [intensity data A1 (1), intensity data A2 (1),..., Intensity data An (1)] is obtained. The hourly data string t1, and thereafter the hourly data string t2 = [intensity data A1 (2), intensity data A2 (2),..., Intensity data An (2)],. tm = [intensity data A1 (m), intensity data A2 (m),..., intensity data An (m)].

  Incidentally, the position-specific data strings A1 to An shown in FIG. 5C are obtained by synthesizing two components of the unnecessary wave component of FIG. 5A and the reflected wave component of FIG. 5B. In FIG. 5, the horizontal axis is the propagation time T, the vertical axis is the intensity, and the waveforms corresponding to the plurality of antenna positions X1 to Xn are arranged in the vertical axis direction. The unnecessary wave component here means an electromagnetic wave that is not reflected by the object B but reflected by the reference surface S or the surface of the object detection device. When the antenna unit 1 having a transmission antenna that transmits electromagnetic waves and a reception antenna that receives electromagnetic waves is used, a direct wave that directly propagates from the transmission antenna to the reception antenna is also included in the unnecessary wave component. These unnecessary wave components do not change even at different antenna positions X1 to Xn, and take steady values as long as the measurement environment does not change greatly. The reflected wave component means an electromagnetic wave reflected by the object B. In addition, although noise components such as randomly generated thermal noise may be included in the position-specific data strings A1 to An as unnecessary wave components, they are unnecessary if the noise components are ignorable compared to the reflected wave components. The noise component is not included in the wave component.

  The temporary unnecessary wave extracting means 16 first extracts intensity data from the storage unit 5 for each hourly data string t1 to tm in order to extract the temporary unnecessary wave component Y0 from the position-specific data strings A1 to An in step S6 of FIG. Take out. Each hourly data string t1 to tm corresponds to a cross section obtained by cutting the data string A1 to An for each position in FIG. 5C at the same sampling timing (the same propagation time T). When the horizontal axis is the antenna position X1 to Xn, the vertical axis is the intensity, and a plurality of hourly data strings t1,..., TN, tN + 1,. In FIG. 6, since the data sequences for each time are relatively compared, the unwanted wave component that does not change even at different antenna positions X1 to Xn is not reflected, and if there is no noise component, the reflected wave in FIG. This corresponds to a cross section obtained by cutting the components at the same sampling timing (same propagation time T).

  One of the hourly data strings shown in FIG. 6 (hourly data string tk) is shown in FIG. In FIG. 7, the horizontal axis represents antenna positions X1 to Xn, and the vertical axis represents intensity. Here, the temporary unnecessary wave extraction means 16 is an intensity range in which a plurality of intensity data A1 (k), A2 (k),..., An (k) constituting the hourly data string tk is distributed (here Then, the intensity data A1 (k), A2 (k),..., An (k) are grouped into intensity sections obtained by dividing the upper and lower ends in FIG. That is, the intensity range is divided into a plurality of intensity intervals in increments of intensity width ΔV, and each intensity data A1 (k), A2 (k),..., An (k) is applied to any intensity interval. Then, the number of pieces of intensity data (number) is compared for each intensity interval, and for the intensity interval (indicated by “P” in FIG. 7) where the number of data is the largest, all the intensity data included in the intensity interval are compared. The average value Y0 (k) is set as a representative value. Similar processing is repeated for all hourly data strings t1 to tm. The temporary unnecessary wave extracting means 16 temporarily does not need the set [Y0 (1), Y0 (2),..., Y0 (m)] of the average value Y0 (k) calculated in this way for all sampling timings. Output as wave component Y0. FIG. 8 shows an example of the temporary unnecessary wave component Y0 extracted by the temporary unnecessary wave extracting means 16 with the propagation time T on the horizontal axis and the intensity on the vertical axis.

  On the other hand, the temporary unnecessary wave removing unit 17 subtracts the output of the temporary unnecessary wave extracting unit 16 (temporary unnecessary wave component Y0) from the position-specific data strings A1 to An in the storage unit 5 in step S7, thereby performing temporary reflection. A wave component C0 is obtained. However, the data strings A1 to An for each position may include different noise components (such as randomly generated thermal noise) for each of the antenna positions X1 to Xn in addition to the temporary unnecessary wave component Y0. A noise component (high frequency component) may be superimposed on the temporary reflected wave component C0 obtained by the temporary unnecessary wave removing unit 17.

  Therefore, in the object detection device of the present embodiment, the calculation unit 11 includes the filter unit 15 (see FIG. 1B) that removes the noise component included in the received signal, thereby improving the extraction accuracy of the temporary unnecessary wave component Y0. I am letting. As the filter means 15, there are many such as an IIR (Infinite Impulse Response) filter, FIR (Finite Impulse Response) filter, or a window function such as a Hamming Window or a Chebyshev approximation applied thereto. There are options, and these may be adopted as appropriate.

  Here, the filter means 15 sets one of the following two as a target for removing a noise component. The first is a set of intensity data for each antenna position X1 to Xn, that is, each position data string A1 to An. For example, for each position data string A3 in FIG. Noise components are removed from A3 (1), A3 (2),..., A3 (m)). The second is a set of intensity data for each sampling timing, that is, each hourly data string t1 to tm. For example, for the hourly data string tk in FIG. 7, the intensity data (a plurality of antenna positions X1 to Xn ( Noise components are removed from A1 (k), A2 (k),..., An (k)). Both filter processes may be combined, such as removing noise components from the data strings A1 to An for each position and then removing noise components from the data strings t1 to tm for each time.

  On the other hand, before obtaining the data strings A1 to An for each position, a noise measuring means (not shown) for measuring noise components such as thermal noise in advance is provided, and the value of the intensity width ΔV of the intensity section used by the temporary unnecessary wave extracting means 16 May be set larger than the maximum amplitude of the noise component measured by the noise measuring means. As a result, the temporary unnecessary wave component Y0 obtained by the temporary unnecessary wave extracting unit 16 is not changed by the influence of the noise component. Therefore, when the filter unit 15 is not used or the noise unit is completely removed by the filter unit 15. Even if it cannot be removed, the influence of the noise component can be ignored.

  However, when the intensity width ΔV is increased, the signal processing time required for extracting the temporary unnecessary wave component Y0 by the temporary unnecessary wave extracting unit 16 is shortened, but the extraction accuracy of the temporary unnecessary wave component Y0 is lowered. For this reason, it is necessary to set an appropriate intensity width ΔV according to the situation of the measurement environment, for example, a value that is twice the maximum amplitude of the noise component is the intensity width ΔV. The noise component information measured by the noise measuring means is stored in the memory 5 (not shown) in the storage unit 5 or the second signal processing unit 4 before detecting the object B, or When the object B is detected, it can be used by the temporary unnecessary wave extraction means 16 by writing in the memory in the storage unit 5 or the signal processing unit 4.

  In addition, the intensity width ΔV of the intensity interval is not set in advance as described above, but the range between the maximum value and the minimum value of the intensity data for the plurality of antenna positions X1 to Xn is set for each sampling timing. The intensity range of the intensity width ΔV may be set by dividing the intensity range by a predetermined constant. Here, for example, if 8-bit calculation is used, the intensity range may be divided into 256 parts. In this case, if the number of intensity data is compared for all 256 intensity intervals, the processing time becomes relatively long. Therefore, the intensity range of each position data string A1 to An is divided into two variable sections, and the variable section where the number of data of the intensity data is the largest among the divided variable sections is divided into two again. The process of gradually narrowing the variable section, such as one-half, four-quarter, one-eighth,..., Is repeated until the variable section corresponds to the intensity section of the intensity width ΔV. desirable. Thereby, shortening of processing time can be aimed at. However, the method of gradually narrowing the variable section and extracting the temporary unnecessary wave component Y0 may not be used depending on the distribution state of the intensity data. Note that the division when the variable section is gradually narrowed is not limited to two divisions, and may be, for example, three divisions.

  In general, the intensity data is distributed in a direction of the intensity axis with respect to the temporary unnecessary wave component Y0. However, in this embodiment, when extracting the temporary unnecessary wave component Y0, the average of all intensity data at each sampling timing is obtained. The temporary unnecessary wave component Y0 is not calculated from the value, but the temporary unnecessary wave component Y0 is calculated from the average value of the intensity data for the intensity interval in which the number of data of the intensity data is maximum. Thus, the provisional unnecessary wave component Y0 can be accurately calculated. Therefore, the provisional reflected wave component C0 can be obtained with high accuracy.

  By the way, in the present embodiment, as will be described below, the unnecessary wave extraction unit 12 extracts the unnecessary wave component Y1 using the above-described provisional reflected wave component C0, thereby reducing the calculated intensity of the reflected wave component C1. Is smaller than the conventional configuration. In the following description, the position-specific data strings A1 to An in FIG. 9C obtained by combining the two components of the unnecessary wave component in FIG. 9A and the reflected wave component in FIG. 9B were obtained. As an example, the operation of calculating the reflected wave component C1 will be described. In FIG. 9, the horizontal axis is the propagation time T, the vertical axis is the intensity, and the waveforms corresponding to the plurality of antenna positions X1 to Xn are arranged in the vertical axis direction. Here, the reflected wave component in FIG. 5B corresponds to the electromagnetic wave reflected by one object B, whereas the reflected wave component in FIG. This corresponds to the electromagnetic wave reflected by the two objects B located.

  In step S8, the data string classification unit 18 analyzes the temporary reflected wave component C0, and classifies the data strings A1 to An for each position in order to extract the unnecessary wave component Y1 again. Here, first, the data string classification means 18 obtains the intensity data (hereinafter referred to as “maximum data”) that is the maximum value of the provisional reflected wave component C0 and the propagation time T of each maximum data for each antenna position X1 to Xn. To detect. The maximum data here may be intensity data that becomes the maximum when the intensity data is compared among the provisional reflected wave components C0, but in the present embodiment, each temporary reflection with respect to the reference waveform. Correlation of the wave component C0 is taken, and intensity data that maximizes the correlation value is used as the maximum data. The waveform of the electromagnetic wave reflected by the object B may differ depending on the attribute (shape, size, material, etc.) of the object B, and therefore, the intensity data is simply compared among the temporarily reflected wave components C0. In this case, it is difficult to detect the maximum intensity data in each case, but the maximum data can be reliably detected by a method that takes a correlation.

  Here, as shown in FIG. 10, the data string classification means 18 has an antenna position X1 that has the maximum intensity (indicated by “P” in FIG. 10) when the maximum data is arranged in the same order as the antenna positions X1 to Xn. ˜Xn are detected, and the antenna position X1 to Xn having the maximum data intensity equal to or higher than a predetermined threshold value K1 is set as a reference position. In FIG. 10 and FIGS. 11 and 16 used in the following description, the horizontal axis represents antenna positions X1 to Xn, and the vertical axis represents intensity. Here, the threshold value K1 is set smaller than the intensity data of the temporarily reflected wave component C0 corresponding to the electromagnetic wave reflected by the object B. As a result, the reference positions are the antenna positions X1 to Xn at which the intensity of the electromagnetic wave reflected by the object B is maximum, and are generally the antenna positions X1 to X1 having the smallest distance from the object B. Xn.

  Then, as shown in FIG. 11, the data string classification means 18 has a predetermined value L1 (provided that the maximum data is the maximum data CM1 at the reference position among the reference position and several antenna positions X1 to Xn before and after the reference position). The data sequences A1 to An for each position at the antenna positions X1 to Xn (the antenna positions X1 to Xn within the predetermined range d including the reference position in FIG. 11) that are equal to or greater than the value multiplied by L1 <1 are the strong data sequences Aa. The other position-specific data strings A1 to An are defined as weak data strings Ab. As a result, the position-specific data strings A1 to An are classified into the strong data string Aa and the weak data string Ab that is less affected by the electromagnetic wave reflected by the object B than the strong data string Aa.

  The threshold value K1 is associated with the maximum data propagation time T so that the propagation time T, which is the elapsed time from when the electromagnetic wave is transmitted to when the maximum data is received, decreases as the propagation time T increases. Since the electromagnetic wave attenuates with the propagation distance, when detecting each of the objects B that differ only in the depth from the reference plane S, the antenna position increases as the depth from the reference plane S to the object B increases. The distance between X1 to Xn and the object B increases, and the intensity of the received signal received at the antenna positions X1 to Xn decreases. Accordingly, as the maximum data propagation time T is longer (that is, the distance between the antenna positions X1 to Xn and the object B is larger) as in the present embodiment, the threshold K1 is set to be smaller, thereby existing at a relatively deep position. There is an advantage that the antenna positions X1 to Xn that have received the electromagnetic waves reflected by the target B to be extracted can be easily extracted as the reference positions.

  As an example of a method for determining the threshold value K1, as shown in FIG. 12, when the propagation time T of the maximum data is arranged in the same order as the antenna positions X1 to Xn, the maximum is greater than the propagation time T0 with a certain propagation time T0 as a boundary. It is conceivable that the threshold when the data propagation time T is early is K1 (1), and the threshold when the data is propagated is K1 (2) smaller than the threshold K1 (1). In FIG. 12, the horizontal axis represents antenna positions X1 to Xn, and the vertical axis represents propagation time T. However, the determination method of the threshold value K1 is not limited to the example of FIG. 12, and for example, the threshold value K1 is expressed by a mathematical expression using the propagation time T as a variable, or a correspondence table showing the correspondence between the propagation time T and the threshold value K1 is used. The correspondence relationship between the threshold value K1 and the propagation time T may be set more finely.

  Further, the above-described predetermined value L1 and the number of antenna positions X1 to Xn before and after the reference position are not necessarily constant values common to all cases. For example, as a function of the propagation time T as in the threshold value K1. Also good. Here, when two objects B that differ only in the depth from the reference plane S are detected at two adjacent antenna positions X1 to Xn, the object B that is deep from the reference plane S. The difference and ratio of the distance from each antenna position X1 to Xn becomes smaller. Since the electromagnetic wave attenuates with the propagation distance, the smaller the difference and ratio of the distance between each antenna position X1 to Xn and the object B, the difference in the intensity of the received signal received at each antenna position X1 to Xn. Becomes smaller. In short, the intensity of the received signal at the antenna positions X1 to Xn becomes gentler in the reflected wave from the object B far from the reference plane S than in the reflected wave from the object B near the reference plane. As the object B is farther from the reference plane S, it is desirable to set the predetermined value L1 larger. In other words, it is desirable to decrease the predetermined value L1 as the propagation time T is shorter.

  The strong data string Aa and the weak data string Ab classified as described above are used for processing in which the unnecessary wave extraction unit 12 extracts the unnecessary wave component Y1 in step S9. In the present embodiment, the unnecessary wave component Y1 is extracted by the same process as the process of step S6 for extracting the temporary unnecessary wave component Y0. However, when extracting the temporary unnecessary wave component Y0, the temporary unnecessary wave component Y0 is extracted using the position-specific data strings A1 to An of all the antenna positions X1 to Xn, whereas the unnecessary wave component Y1 is extracted. When extracting, the unnecessary wave component Y1 is extracted using only the weak data string Ab among the position-specific data strings A1 to An.

  In short, the unnecessary wave extracting means 12 has an intensity in which a plurality of intensity data A1 (k), A2 (k),..., An (k) are distributed at the same sampling timing with respect to the weak data string Ab. These intensity data A1 (k), A2 (k),..., An (k) are grouped into intensity sections obtained by dividing the range by a certain intensity width ΔV. That is, the intensity range is divided into a plurality of intensity intervals in increments of intensity width ΔV, and each intensity data A1 (k), A2 (k),..., An (k) is applied to any intensity interval. Then, the number of pieces of intensity data (number) is compared for each intensity section, and the average value Y1 (k) of all intensity data included in the intensity section is used as a representative value for the intensity section having the largest number of data. To do. Similar processing is repeated for all sampling timings. The unnecessary wave extracting means 12 uses the set [Y1 (1), Y1 (2),..., Y1 (m)] of the average value Y1 (k) calculated in this way for all sampling timings as unnecessary wave components. Output as Y1. The advantage of the method described in step S6 is that the unnecessary wave component Y1 can be extracted with high accuracy.

  Here, the process of extracting the unnecessary wave component Y1 does not have to be the same as the process of step S6 of extracting the temporary unnecessary wave component Y0. For example, the weak data strings Ab are compared at the same sampling timing, and the intensity data is averaged. The unnecessary wave component Y1 may be extracted using the value or the median as a representative value. When taking the average value of the intensity data, a value obtained by dividing the sum of the intensity data of the weak data strings Ab at the same sampling timing by the number of weak data strings Ab is defined as an average value Y1 (k). The unnecessary wave extracting means 12 repeats the same processing for all sampling timings, and the set of average values Y1 (k) calculated in this way for all sampling timings [Y1 (1), Y1 (2),. , Y1 (m)] is output as an unnecessary wave component Y1. On the other hand, when taking the median value of the intensity data, the intensity data of the weak data string Ab at the same sampling timing is rearranged in order of magnitude, and the intensity data located at the center is set to the median value Y1 (k). The unnecessary wave extracting unit 12 repeats the same processing for all sampling timings, and the set of all the sampling timings of the median value Y1 (k) calculated in this way [Y1 (1), Y1 (2),. , Y1 (m)] is output as an unnecessary wave component Y1.

  Since the method of using the average value of intensity data as a representative value is the simplest, there is an advantage that the signal processing speed is high and the component cost can be suppressed. Depending on the application, it is conceivable that this method cannot be put into practical use due to limitations on the signal processing speed. The method using the median value as the representative value generally increases the accuracy although the signal processing time is longer than the method using the average value. Therefore, an optimal method may be selected according to specifications required for the object detection device. Further, in the process of step S6 for extracting the temporary unnecessary wave component Y0, the average value or the median value of the intensity data may be used as the representative value. Whichever method is used, it is not necessary to use all the intensity data, and it is extremely smaller than the intensity data at the front and rear antenna positions X1 to Xn due to a measurement error or the like due to a malfunction of the object detection device (or As a countermeasure when an abnormal value (large) is detected, intensity data for several pieces from the minimum or maximum value corresponding to the abnormal value may be ignored.

  The unnecessary wave removing unit 13 calculates the reflected wave component C1 by subtracting the unnecessary wave component Y1 extracted as described above from each position data string A1 to An in step S10.

  Here, FIG. 13 shows the actual reflected wave component C3 corresponding to the electromagnetic wave reflected by the object B, FIG. 14 shows the reflected wave component C2 calculated by the conventional method, and FIG. 15 shows the reflected wave component calculated in the present embodiment. Each of the wave components C1 is shown. 13 to 15, the horizontal axis is the propagation time T, the vertical axis is the intensity, and the waveforms corresponding to the plurality of antenna positions X1 to Xn are arranged in the vertical axis direction. Since the reflected wave component C2 calculated by the conventional method of FIG. 14 is calculated by subtracting the unnecessary wave component including the actual reflected wave component C3 from the position-specific data strings A1 to An, the actual reflected wave component C3 is calculated. In this case, a maximum value of extra strength that does not exist appears and the waveform is distorted. On the other hand, the reflected wave component C1 of the present embodiment has an advantage that such an extraordinary intensity maximum value does not appear, and the waveform distortion is less than that of the reflected wave component C2.

  FIG. 16 shows the maximum intensity for each antenna position X1 to Xn for the actual reflected wave component C3, the reflected wave component C2 calculated by the conventional method, and the reflected wave component C1 calculated in the present embodiment. The intensity data (values indicated by black dots in FIGS. 13 to 15) are arranged in the same order as the antenna positions X1 to Xn. Here, the reflected wave component C2 calculated by the conventional method is calculated by subtracting the unnecessary wave component including the actual reflected wave component C3 from the position-specific data strings A1 to An. Therefore, the actual reflected wave component C3 is calculated. The strength is greatly attenuated compared to. On the other hand, the reflected wave component C1 calculated in the present embodiment is not attenuated in intensity compared to the actual reflected wave component C3 corresponding to the electromagnetic wave reflected by the object B. In short, in the present embodiment, the reflected wave component C1 can be calculated without attenuating the intensity.

  The detection unit 14 of the present embodiment analyzes the reflected wave component C1 for the plurality of antenna positions X1 to Xn obtained by the unnecessary wave removing unit 13 as described above in step S11, and the intensity of the reflected wave component C1 is predetermined. The presence or absence of the object B is detected depending on whether or not the threshold value is exceeded. Here, the intensity of the reflected wave component C1 varies depending on the reflectance of the electromagnetic wave on the object B, and the reflectance varies depending on the material of the object B. By setting in accordance with the reflectance, it is possible to detect only the object B made of a specific material while ignoring an object having a smaller electromagnetic wave reflectance than the object B. The detection means 14 may be configured to detect a state other than the presence or absence of the object B based on the reflected wave component C1, for example, the distance to the object B, the size or shape of the object B, or It is conceivable to cause the detection means 14 to detect the material, and also the characteristics (for example, the dielectric constant) of the propagation medium (wall material or the like) existing between the antenna unit 1 and the object B. Actually, since the attenuation amount of the electromagnetic wave varies depending on the propagation distance, the propagation distance is calculated from the time required for the electromagnetic wave to be received by the antenna unit 1 after being transmitted from the antenna unit 1 and the speed of the electromagnetic wave, By considering the attenuation effect, each characteristic can be detected with higher accuracy.

  Here, according to the configuration of the present embodiment, the reflected wave component C1 close to the actual reflected wave component C3 corresponding to the electromagnetic wave reflected by the object B can be calculated as described above. Various analysis results obtained by analyzing the reflected wave component C1 are also accurate.

  Various analysis results obtained by the detection means 14 are output from the output unit 6 in step S12. The output unit 6 includes a display monitor (not shown) for displaying the analysis result in a visually recognizable form. In addition, the output unit 6 stores a device such as a speaker for outputting sound and the analysis result. And a storage device, an arithmetic unit for performing further detailed analysis, and the like may be added to support various output forms. In most applications, not only the process from the process (S2) of fetching the data strings A1 to An for each antenna position X1 to Xn into the storage unit 5 to the output of analysis results (S12) is performed once, Repeat. In this case, the process is repeated again from step S2 (S13).

  Further, in the object detection device of the present embodiment, an ultra wide band (UWB) pulse signal is transmitted as an electromagnetic wave from the antenna unit 1. If a UWB signal is transmitted, an electromagnetic wave having a very narrow pulse width can be transmitted from the antenna unit 1, so that the detection accuracy of the time required to transmit and receive the electromagnetic wave is improved. Detection accuracy such as distance is improved. In addition, the difference in waveform between the unnecessary wave component Y1 and the reflected wave component C1 becomes clear, and the extraction accuracy of the unnecessary wave component Y1 can be improved.

  By the way, in order to detect the object B existing in the back of the reference plane S composed of the ground surface or the structure surface, generally, as described above, electromagnetic waves are transmitted and received at the plurality of antenna positions X1 to Xn. Collect signals. In the present embodiment, in order to transmit and receive electromagnetic waves at a plurality of antenna positions X1 to Xn, moving means for moving the object detection device itself so that the antenna unit 1 moves to each antenna position X1 to Xn (see FIG. 2). (Not shown). As the moving means, a configuration having wheels that roll on the reference plane S is adopted, but the configuration is not limited to this configuration. For example, the object detection device is moved along a rail passing through a plurality of antenna positions X1 to Xn. The structure etc. to be made can be considered. Here, the antenna unit 1 is configured to transmit an electromagnetic wave from one antenna and receive the electromagnetic wave through the antenna, thereby reducing the size of the antenna unit 1.

  Further, the antenna unit 1 may have a configuration including one transmitting antenna that transmits electromagnetic waves and one receiving antenna that receives electromagnetic waves. In this case, the antenna unit 1 is moved to each antenna position X1 to Xn. A moving means is provided. Furthermore, the antenna unit 1 may include a plurality of antennas that transmit and receive electromagnetic waves, or may include a plurality of sets of transmission antennas and reception antennas. Moving means for moving to the antenna positions X1 to Xn is provided.

  Here, when a pair of a transmitting antenna and a receiving antenna is arranged at each antenna position X1 to Xn, or when an antenna for transmitting and receiving electromagnetic waves is arranged at each antenna position X1 to Xn, respectively. By using one set of transmission antennas and one reception antenna (or one antenna each), and sequentially switching the combination of transmission antennas and reception antennas used (or antennas used), Since the antenna positions X1 to Xn can be switched without moving the part 1, the moving means can be omitted.

  Further, the operation of the data string classification unit 18 is not limited to the operation of the above-described embodiment. For example, the data string classification means 18 uses the position-specific data strings A1 to An at the antenna positions X1 to Xn in a predetermined number before and after the reference position as the strong data string Aa, and other position-specific data strings. A1 to An may be the weak data string Ab. In this case, since the number of the position-specific data strings A1 to An as the strong data string Aa is fixed with respect to one reference position, the measurement error due to the malfunction of the object detection device at the antenna positions X1 to Xn before and after the reference position. Even if an abnormal value that is extremely small compared to the maximum data at the front and rear antenna positions X1 to Xn is detected due to the above, the position-specific data strings A1 to An of the antenna positions X1 to Xn where the abnormal values are detected are also strong data strings. By setting Aa, it becomes possible to remove the influence of the abnormal value. In this case, although the influence of the abnormal value appears in the calculated reflected wave component C1, an appropriate process may be performed at that stage.

  Alternatively, the data string classification unit 18 may use the position-specific data strings A1 to An as the strong data string Aa and the other position-specific data strings A1 to An as the weak data string Ab. Since the amount can be reduced, this method is effective for applications that require high-speed processing, and leads to cost reduction by simplifying the second signal processing unit 4.

  Furthermore, the data string classification means 18 can classify the data strings A1 to An for each position into the strong data string Aa and the weak data string Ab without detecting the reference position. In this case, the data string classification unit 18 sets all the position-specific data strings A1 to An at the antenna positions X1 to Xn at which the maximum data is equal to or greater than the threshold value K1 among all the antenna positions X1 to Xn as intensity data strings Aa. The position-specific data strings A1 to An are classified by setting the position-specific data strings A1 to An as weak data strings Ab. This method can also reduce the amount of calculation processing, and thus is effective for applications that require high-speed processing, and also leads to cost reduction by simplifying the second signal processing unit 4.

  When these processes different from the above-described embodiment are adopted as the operation of the data string classification unit 18, the threshold value K1 used when the data string classification unit 18 determines the reference position in step S8 in FIG. The threshold value is not limited to the same value as in the above-described embodiment, and is set as appropriate.

(Embodiment 2)
The object detection apparatus according to the present embodiment is different from the object detection apparatus according to the first embodiment in the threshold value K1 setting method used when the data string classification unit 18 determines the reference position in step S8 in FIG. Other configurations and functions are the same as those of the first embodiment.

  In the present embodiment, the threshold value K1 is set to a predetermined value in advance at the time of initialization (S1), and this threshold value K1 does not vary with the propagation time T of the maximum data. In general, in an application in which the object B to be measured is limited to a region that is relatively close (shallow) from the reference surface S, the threshold value K1 does not need to be set finely as in the first embodiment. That is, even if the constant threshold value K1 is set as in the present embodiment, the reflected wave component C1 is calculated with the same accuracy as in the first embodiment if an appropriate threshold value K1 is set according to the measurement target. can do. Note that the threshold value K1 may be set in consideration of the depth of the object B to be measured from the reference plane S as well as the reflectance of the object B to be measured.

  According to this configuration, compared to the configuration of the first embodiment, the calculation processing speed is greatly improved and the second signal processing unit 4 is increased by the amount that the calculation processing for determining the threshold value K1 according to the propagation time T is unnecessary. In some cases, the cost can be reduced by simplifying the system. Note that the threshold value K1 may be set in advance at the time of manufacturing the object detection device, and the value set by the input unit 8 may be set as the threshold value K1.

(Embodiment 3)
In the object detection device of this embodiment, in step S8 of FIG. 4, when the data sequence classification unit 18 arranges the propagation time T of the maximum data in the same order as the antenna positions X1 to Xn (see FIG. 12), the propagation time T The antenna positions X1 to Xn that are the minimum (indicated by “Q” in FIG. 12) are detected, and the point where the maximum data intensity among the antenna positions X1 to Xn is the threshold value K1 or more is the reference position. This is different from the object detection device according to the first embodiment. Other configurations and functions are the same as those of the first embodiment.

  According to this configuration, even when noise is superimposed on the electromagnetic wave reflected by the object B and the intensity of each maximum data does not take an accurate value, the reference position is detected from the maximum data that minimizes the propagation time T. Therefore, the influence of noise can be reduced. Further, the antenna positions X1 to Xn at which the intensity is maximized as described in the first embodiment are also detected, and may be comprehensively determined together with the antenna positions X1 to Xn at which the propagation time T is minimized. The reference position detection accuracy is further improved, and the calculation accuracy of the reflected wave component C1 is improved.

  In this embodiment, the threshold K1 used when the data string classification unit 18 determines the reference position is associated with the maximum data propagation time T so as to increase as the maximum data propagation time T decreases. However, like the second embodiment, the threshold value K1 may be set to a constant value in advance.

1 shows Embodiment 1 of the present invention, in which (a) is a block diagram and (b) is a block diagram of a main part. It is operation | movement explanatory drawing same as the above. (A) is explanatory drawing which shows the data string for every position same as the above, (b) is explanatory drawing to which a part Z of (a) was expanded. It is a flowchart which shows operation | movement same as the above. It is operation | movement explanatory drawing same as the above, (a) is explanatory drawing which shows an unnecessary wave component, (b) is explanatory drawing which shows a reflected wave component, (c) is explanatory drawing which shows the data string for every position. It is operation | movement explanatory drawing same as the above. It is operation | movement explanatory drawing same as the above. It is explanatory drawing which shows an example of an unnecessary wave component same as the above. It is operation | movement explanatory drawing same as the above, (a) is explanatory drawing which shows an unnecessary wave component, (b) is explanatory drawing which shows a reflected wave component, (c) is explanatory drawing which shows the data string for every position. It is operation | movement explanatory drawing same as the above. It is operation | movement explanatory drawing same as the above. It is operation | movement explanatory drawing same as the above. It is explanatory drawing which shows an actual reflected wave component. (A) is explanatory drawing which shows the reflected wave component calculated by the conventional method, (b) is explanatory drawing to which a part Z of (a) was expanded. (A) is explanatory drawing which shows the reflected wave component calculated in Embodiment 1 of this invention, (b) is explanatory drawing to which a part Z of (a) was expanded. It is operation | movement explanatory drawing same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Antenna part 5 Memory | storage part 10 A / D conversion part (sampling means)
DESCRIPTION OF SYMBOLS 12 Unwanted wave extraction means 13 Unwanted wave removal means 14 Detection means 16 Temporary unnecessary wave extraction means 17 Temporary unnecessary wave removal means 18 Data string classification means A1-An Data string for every position Aa Strong data string Ab Ab weak data string B Object C0 Temporary Reflected wave component C1 Reflected wave component K1 Threshold value L1 Predetermined value S Reference plane X1 to Xn Antenna position Y0 Temporary unnecessary wave component Y1 Unwanted wave component

Claims (13)

  Electromagnetic waves are intermittently transmitted from the antenna section toward the reference plane at a plurality of antenna positions along the reference plane set in the detection area, and the electromagnetic waves reflected by the object existing behind the reference plane are transmitted by the antenna section. An object detection device that detects an object by receiving and converting it into a received signal that is an electrical signal, and uses the intensity of the received signal received at each antenna position as intensity data at each sampling interval of a predetermined interval. Sampling means for storing a set of data for each antenna position in the storage unit as a data string for each position, unnecessary wave extracting means for extracting unnecessary wave components commonly included in the data string for each position at each antenna position, and each antenna The reflected wave component corresponding to the electromagnetic wave reflected by the object is obtained by subtracting the unnecessary wave component from the position-specific data string at the position. A required wave removing means, and a detecting means for detecting the state of the object based on the intensity of the reflected wave components at a plurality of antenna positions and the elapsed time from when the electromagnetic wave is transmitted until the reflected wave component is received, The unnecessary wave extraction means obtains a representative value of the intensity data for each sampling timing that is the same for the data string for each position stored in the storage unit, and extracts a set of a plurality of sampling timings of the representative value as temporary unnecessary wave components. Temporary unnecessary wave extracting means, temporary unnecessary wave removing means for obtaining temporary reflected wave components by subtracting temporary unnecessary wave components from the position-specific data string at each antenna position, and position-specific data string stored in the storage unit Is a strong data that is a data string for each position of the antenna position within a predetermined range including the antenna position where the intensity of the electromagnetic wave reflected by the object in the temporarily reflected wave component is the maximum. Data string classification means for classifying the data into a weak data string other than the strong data string, and obtaining a representative value of the intensity data for each of the same sampling timing with respect to the weak data string. An object detection apparatus characterized in that the set of unnecessary waves is used as the set of unnecessary waves.   The data string classification unit detects intensity data that is the maximum value of the provisional reflected wave component at each antenna position as maximum data, and the maximum intensity is obtained when the maximum data is arranged in the same order as the antenna position. Among the antenna positions, the antenna position where the maximum data is greater than or equal to a predetermined threshold is used as a reference position, and the maximum data is less than 1 in the reference position and the plurality of antenna positions before and after the reference position. The object detection device according to claim 1, wherein the data string for each position at an antenna position that is equal to or greater than a value obtained by multiplying the predetermined value is the strong data string.   The data string classification unit detects intensity data that is the maximum value of the provisional reflected wave component at each antenna position as maximum data, and the maximum intensity is obtained when the maximum data is arranged in the same order as the antenna position. Among the antenna positions, the antenna position where the maximum data is equal to or greater than a predetermined threshold is set as a reference position, and the strong position data string is the reference position and the position-specific data string at a preset number of antenna positions before and after the reference position. The object detection device according to claim 1, wherein:   The data string classification unit detects intensity data that is the maximum value of the provisional reflected wave component at each antenna position as maximum data, and the maximum intensity is obtained when the maximum data is arranged in the same order as the antenna position. 2. The object detection according to claim 1, wherein among the antenna positions, the antenna position where the maximum data is equal to or greater than a predetermined threshold is set as a reference position, and the data string for each position at the reference position is set as the strong data string. apparatus.   The data string classification unit detects, as maximum data, intensity data that is the maximum value of the provisional reflected wave component at each antenna position, and the maximum data is equal to or greater than a predetermined threshold among the plurality of antenna positions. The object detection apparatus according to claim 1, wherein the position-specific data string at the antenna position is the intensity data string.   The data string classification means detects the intensity data that is the maximum value of the provisional reflected wave component at each antenna position as maximum data, and determines the elapsed time from when the electromagnetic wave is transmitted until the maximum data is received. Among the antenna positions that are the minimum of the elapsed time when arranged in the same order as the antenna positions, the antenna position whose maximum data is equal to or greater than a predetermined threshold is set as a reference position, and the reference position and a plurality of antenna positions before and after the reference position 2. The data string for each position at an antenna position where the maximum data is equal to or greater than a value obtained by multiplying the maximum data at the reference position by a predetermined value less than 1 is defined as the strong data string. Object detection device.   The data string classification means detects the intensity data that is the maximum value of the provisional reflected wave component at each antenna position as maximum data, and determines the elapsed time from when the electromagnetic wave is transmitted until the maximum data is received. Among the antenna positions that have the minimum elapsed time when arranged in the same order as the antenna positions, the antenna position whose maximum data is equal to or greater than a predetermined threshold is set as a reference position, and the reference position and the reference position are set in advance before and after the reference position. 2. The object detection device according to claim 1, wherein the strong data string is the data string for each position at a number of antenna positions.   The data string classification means detects the intensity data that is the maximum value of the provisional reflected wave component at each antenna position as maximum data, and determines the elapsed time from when the electromagnetic wave is transmitted until the maximum data is received. Among the antenna positions that have the minimum elapsed time when arranged in the same order as the antenna positions, the antenna position whose maximum data is equal to or greater than a predetermined threshold is set as a reference position, and the data string for each position at the reference position is set as the strong position. The object detection device according to claim 1, wherein the object detection device is a data string.   9. The threshold value according to claim 2, wherein the threshold value is associated with the elapsed time such that the longer the elapsed time from when the electromagnetic wave is transmitted until the maximum data is received, the smaller the threshold value is. The object detection apparatus of any one of Claims.   The object detection device according to claim 2, wherein the threshold value is set to a predetermined value in advance.   At least one of the provisional unnecessary wave extraction means and the unnecessary wave extraction means has an intensity range in which intensity data of a plurality of the antenna positions is distributed as an intensity section having a certain intensity width at the same sampling timing. 11. The object detection according to claim 1, wherein the representative value is an average value of intensity data obtained by dividing and obtaining an intensity interval in which the number of intensity data is the largest. apparatus.   At least one of the provisional unnecessary wave extracting unit and the unnecessary wave extracting unit uses a median value of intensity data of a plurality of the antenna positions obtained at the same sampling timing as the representative value. The object detection device according to any one of claims 1 to 10. At least one of the temporary unnecessary wave extracting unit and the unnecessary wave extracting unit uses an average value of intensity data of the plurality of antenna positions obtained at the same sampling timing as the representative value. The object detection device according to any one of claims 1 to 10.

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