Obstacle detection device and obstacle detection method

Abstract

To enable an obstacle detection device designed to improve detection accuracy to be realized by a simple device composition.SOLUTION: An obstacle detection device 1 for transmitting / receiving wireless signals and detecting obstacles in a detection target range on a trajectory comprises: a transmitter 10 that transmits a prescribed transmit signal from a prescribed transmit position; a receiver 20 that receives at a prescribed receive position; a propagation path transfer function calculation unit 34 that calculates, on the basis of the analysis result of having analyzed the frequencies of transmitted and received signals, a propagation path transfer function including a frequency response component that pertains to a reflected wave propagation path from being transmitted from the transmit position to being received at the receive position; and an obstacle presence determination unit 35 that determines, on the basis of a reference propagation path transfer function and the propagation path transfer function, the presence of obstacles in a detection target range.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an obstacle detection device for detecting obstacles on a track and the like.

Background Art

[0002] In railway, for the introduction of automatic train operation control, in order to prevent accidents, a technology for detecting obstacles on the track and stopping the train as necessary is required. As a technology for detecting obstacles on the track, for example, a technology of installing a detection device in which a radar device and a reflector (reflective member) are integrated on the ground (see, for example, Patent Document 1), or a technology of mounting a millimeter-wave radar on the front part (on the vehicle) of a train (see, for example, Patent Document 2) is known.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] From the viewpoint of safety, further improvement in detection accuracy is required for an obstacle detection device. In addition, since the track is long and there are many trains running on the track, a large number of detection devices are required, and in order to reduce the costs required for installation and maintenance of the detection devices, it is also required to have a simple device configuration.

[0005] The problem to be solved by the present invention is to make it possible to realize an obstacle detection device with improved detection accuracy by a simple device configuration.

Means for Solving the Problems

[0006] A first invention for solving the above problems is An obstacle detection device that transmits and receives wireless signals to detect obstacles within a detection range on the orbit, A transmitting means (for example, the transmitter 10 in Figure 1) that transmits a predetermined transmission signal from a predetermined transmission position, A receiving means that receives at a predetermined receiving position (for example, the receiver 20 in Figure 1), A calculation means (for example, the propagation path transfer function calculation unit 34 in Figure 1) calculates a propagation path transfer function that includes the frequency response component related to the propagation path of the reflected wave from the time it is transmitted at the transmission position until it is received at the reception position, based on the analysis results obtained by frequency analysis of the transmitted signal and the received signal of the receiving means, A determination means (for example, the obstacle presence / absence determination unit 35 in Figure 1) determines the presence or absence of the obstacle within the detection target range based on the reference propagation path transfer function which serves as a comparison standard for the propagation path transfer function and the propagation path transfer function, This is an obstacle detection device equipped with [a specific feature / feature].

[0007] Other inventions include, An obstacle detection method that detects obstacles within a detection range on an orbit by transmitting and receiving wireless signals, Based on the analysis results obtained by frequency analysis of a predetermined transmitted signal transmitted from a predetermined transmitting position and a predetermined received signal received at a predetermined receiving position, a propagation path transfer function including the frequency response component related to the propagation path of the reflected wave from the time it is transmitted at the transmitting position to the time it is received at the receiving position is calculated (for example, step S3 in Figure 4). Based on the reference path transfer function that serves as the comparison standard for the aforementioned path transfer function and the aforementioned path transfer function, the presence or absence of the obstacle within the detection target range is determined (for example, steps S5 to S9, S11 in Figure 4), An obstacle detection method including this may be configured.

[0008] According to the first invention, an obstacle detection device with improved detection accuracy can be realized with a simple device configuration. Specifically, it detects obstacles within the detection range on the orbit by transmitting and receiving wireless signals, but the presence or absence of obstacles is determined based on a propagation path transfer function calculated from the analysis results of frequency analysis of the transmitted and received signals, and a reference propagation path transfer function that serves as a comparison standard. The propagation path transfer function includes the frequency response component related to the propagation path of the reflected wave from the transmission position to the reception position. The reference propagation path transfer function can be, for example, a propagation path transfer function that can be used as a standard for determining the presence or absence of obstacles, such as the propagation path transfer function when there are no obstacles within the detection range. This makes it possible to accurately determine the presence or absence of obstacles within the detection range. Furthermore, since the propagation path transfer function is based on the analysis results of frequency analysis of the transmitted and received signals, it is less affected by fluctuations in the transmitted signal. This further improves the accuracy of determining obstacles within the detection range on the orbit. As described above, according to the first invention, it is possible to accurately determine the presence or absence of obstacles within the detection range on the orbit, even with a simple configuration that involves signal processing of the transmitted signal and the received signal.

[0009] The second invention is, in the first invention, The calculation means calculates the propagation path transfer function as the ratio of the frequency components of the transmitted signal and the frequency components of the received signal. An estimation means (for example, the obstacle position estimation unit 36 ​​in Figure 1) that estimates the position of the obstacle based on the difference between the reference propagation path transfer function and the propagation path transfer function, This obstacle detection device is further equipped with the following features.

[0010] According to the second invention, the position of an obstacle can be estimated based on the difference between a reference path transfer function and a propagation path transfer function. The reference path transfer function is a propagation path transfer function that can be used as a criterion for determining the presence or absence of an obstacle, such as the propagation path transfer function when there are no obstacles within the detection range. Therefore, the difference between the reference path transfer function and the propagation path transfer function can be determined to correspond to the frequency components of the reflected wave from the obstacle within the detection range. In this way, the position of an obstacle can be estimated with high accuracy based on the difference between the reference path transfer function and the propagation path transfer function.

[0011] The third invention is, in the second invention, The estimation means estimates the direction of arrival of the reflected wave from the obstacle based on frequency components that satisfy a predetermined relative amplitude difference condition with respect to the reference propagation path transfer function included in the propagation path transfer function. It is an obstacle detection device.

[0012] According to the third invention, the direction of arrival of a reflected wave from an obstacle can be estimated based on frequency components that satisfy a predetermined relative amplitude difference condition with respect to a reference propagation path transfer function included in the propagation path transfer function. By using frequency components that satisfy a predetermined relative amplitude difference condition with respect to a reference propagation path transfer function included in the propagation path transfer function, it becomes possible to extract, for example, only the frequency components of the reflected signal from the obstacle, and based on these frequency components, it becomes possible to accurately estimate the direction of arrival of the reflected wave from the obstacle, that is, the direction of the obstacle. Furthermore, the propagation path transfer function includes frequency response components related to the propagation path of the reflected wave. Therefore, from the magnitude of the amplitude (received intensity) related to the reflected wave, the distance from the transmission position to the obstacle to the receiving position, which is the propagation path of the radio signal related to the reflected wave, can be determined. Consequently, it is also possible to estimate the position of the obstacle from these.

[0013] The fourth invention is, in any of the first to third inventions, An update means (for example, the reference path transfer function update unit 37 in Figure 1) updates the reference path transfer function using the propagation path transfer function determined to be free of obstacles by the determination means. It is an obstacle detection device further comprising

[0014] According to the fourth invention, it is possible to further improve the detection accuracy of obstacles. That is, since the environment along the line may change over time, even if there are no obstacles within the detection target range, the received signal may change, and as a result, the propagation path transfer function may also change. Therefore, by updating the reference propagation path transfer function using the propagation path transfer function determined to have no obstacles, it is possible to obtain a reference propagation path transfer function that reflects the latest environment, and it becomes possible to improve the detection accuracy of obstacles.

Brief Description of the Drawings

[0015] [Figure 1] An application example of the obstacle detection device. [Figure 2] An explanatory diagram of the detection of obstacles. [Figure 3] An explanatory diagram of the detection target range. [Figure 4] A flowchart of the obstacle detection process.

Embodiments for Carrying Out the Invention

[0016] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. Note that the form to which the present invention is applicable is not limited to the following embodiments. Also, in the description of the drawings, the same reference numerals are assigned to the same elements.

[0017] [Overall Configuration] FIG. 1 is an application example of the obstacle detection device in the present embodiment. The obstacle detection device 1 is a device that transmits and receives wireless signals to detect obstacles within the detection target range on the track, and includes a transmitter 10, a receiver 20, and a signal processing unit 30. As the detection target range, for example, a range including a level crossing can be set as the target range, a range including the track beside the platform can be set as the target range, or a range including the track in the mountainous area where rockfalls and avalanches may occur can be set as the target range.

[0018] The transmitter 10 is installed near the orbit and transmits a radio signal from its directional antenna towards the detection target range on the orbit. Specifically, it converts the transmitted OFDM (Orthogonal Frequency Division Multiplexing) signal input from the transmitted OFDM signal generation unit 32 of the signal processing unit 30 into a radio frequency signal (radio signal) by performing orthogonal modulation processing using the oscillation signal input from the oscillation unit 31 of the signal processing unit 30, and then transmits it.

[0019] The receiver 20 is installed along the track and receives radio signals, including reflected signals, from the detection target range on the track using a directional antenna. In other words, the received radio signal (received signal) is converted into a received OFDM signal by quadrature demodulation processing using the oscillation signal input from the oscillation unit 31 of the signal processing unit 30, and output to the signal processing unit 30.

[0020] The signal processing unit 30 determines whether there are any obstacles within the detection range on the orbit based on the transmitted signal (wireless signal) sent by the transmitter 10 and the received signal (wireless signal) received by the receiver 20, and if it determines that there are obstacles, it estimates the location of those obstacles.

[0021] The detection of obstacles by the signal processing unit 30 (determination of the presence or absence of obstacles and estimation of the location of obstacles) will be explained below. Obstacle detection is performed using a propagation path transfer function based on the analysis results obtained by frequency analysis of the transmitted signal and the received signal. The propagation path transfer function includes the frequency response components related to the propagation path of the reflected wave from the transmission position (installation position of the transmitter 10) to the reception position (installation position of the receiver 20), and is calculated as the ratio of the frequency components of the transmitted signal and the frequency components of the received signal. In this embodiment, FFT (Fast Fourier Transformation) is performed as the frequency analysis. Therefore, the propagation path transfer function relating to the propagation path of the radio signal from the transmission position (installation position of the transmitter 10) to the reception position (installation position of the receiver 20) is expressed by the following equation (1). A×exp(-i×2π×(D / λ))···(1) In equation (1), "D" is the distance of the propagation path, and "λ" is the wavelength (=speed of light C / f) determined by the subcarrier frequency f. Since the propagation path transfer function is a signal in the frequency domain, a peak appears in the frequency spectrum (amplitude spectrum) representing this propagation path transfer function at a frequency F (=distance D / wavelength λ) corresponding to the propagation path distance D. Furthermore, the value of this peak is the amplitude A in equation (1) of the propagation path transfer function. The distance D can include, for example, the distance D1 of the direct wave in Figure 1, as well as the distances D2 and D3 of the reflected wave (indirect wave) reflected by some object.

[0022] The presence or absence of obstacles is determined based on this propagation path transfer function and a reference propagation path transfer function used as a comparison standard. The reference propagation path transfer function is the propagation path transfer function when there are no obstacles within the detection range. However, the propagation path from the transmission position to the reception position of a wireless signal includes not only the path of receiving the direct wave from the transmission position at the reception position, but also the path of receiving reflected waves (indirect waves) reflected by some object, including the ground. Therefore, even though the reference propagation path transfer function is said to be the propagation path transfer function when there are no obstacles within the detection range, it may include some indirect waves in addition to the direct wave. Accordingly, in this embodiment, a correlation value is calculated as the similarity between the propagation path transfer function and the reference propagation path transfer function to determine the presence or absence of obstacles. If the calculated correlation value is above a predetermined threshold, it is determined to be "no obstacles," and if it is below the threshold, it is determined to be "obstacles present."

[0023] Alternatively, the propagation path transfer function and similarity may be calculated repeatedly at predetermined time intervals, and if the similarity remains above a predetermined threshold for a predetermined number of times (e.g., 3 times) or for a predetermined time (e.g., 5 seconds) or longer, it may be determined that there are "no obstacles," and if the similarity remains below the threshold for a predetermined number of times or for a predetermined time or longer, it may be determined that there are "obstacles." Alternatively, for calculating similarity, machine learning may be performed to calculate similarity using a reference propagation path transfer function as training data, and the obtained new propagation path transfer function may be input to calculate similarity.

[0024] If an "obstacle present" is detected, the location of the obstacle is then estimated based on the difference between the propagation path transfer function and the reference propagation path transfer function. The reference propagation path transfer function is the propagation path transfer function when there are no obstacles within the detection range. Therefore, the difference between the propagation path transfer function and the reference propagation path transfer function can be said to be the frequency response component for the reflected wave from the obstacle within the detection range. Accordingly, the propagation path distance D of the radio signal (indirect wave) related to the reflected wave from the transmission position (installation position of transmitter 10) to the obstacle and then to the reception position (installation position of receiver 20) is determined based on the frequency F at which a peak occurs in the frequency spectrum (amplitude spectrum) representing the difference between this propagation path transfer function and the reference propagation path transfer function. Therefore, the direction of arrival of the reflected wave from the obstacle is estimated using the MUSIC algorithm or the ESPRIT algorithm, which are direction-of-arrival estimation algorithms. From the distance D and direction of arrival obtained above, the relative positions of the obstacles to the transmission position (installation position of transmitter 10) and the reception position (installation position of receiver 20) are estimated.

[0025] Furthermore, since the environment along the track, including objects surrounding the track, can change over time, the received signal can also change, and as a result, the propagation path transfer function can also change. For this reason, the direction of arrival of reflected waves from obstacles is estimated based on frequency components that satisfy a predetermined relative amplitude difference condition with respect to the reference propagation path transfer function included in the propagation path transfer function. In other words, the direction of arrival of reflected waves from obstacles is estimated based on frequency components in the difference between the propagation path transfer function and the reference propagation path transfer function where the relative amplitude difference is greater than or equal to a predetermined value.

[0026] Figure 2 shows an example of obstacle detection based on the propagation path transfer function. In Figure 2, for the sake of clarity, it is explained that three signals are received: the direct wave from the transmission position to the reception position, the reflected wave from a non-obstacle object (an object that is not an obstacle) that is within the detectable range but outside the target detection range, and the reflected wave from an obstacle that is both within the detectable range and within the target detection range.

[0027] Here, the detectable range and the detection target range will be explained with reference to Figure 3. Figure 3 is a diagram illustrating the detection target range of the obstacle detection device 1. Figure 3 shows a schematic top view of the railway track as seen from above. The detection target range is the range in which obstacles are to be detected in advance, and is defined as a predetermined range on the track. The detection target range can be set arbitrarily, and by setting it to the building clearance range, objects detected within the detection target range can be recognized as obstacles.

[0028] The detectable range is the range in which the presence of any object can be detected by the wireless signals transmitted and received by the directional antennas of the transmitter 10 and receiver 20, and is determined by the installation position and orientation of the transmitter 10 and receiver 20, communication performance, etc. The transmitter 10 and receiver 20 are designed, configured, and installed so that the detectable range includes the detection target range. Note that in Figure 3, the detection target range and the detectable range are shown as two-dimensional ranges, but in reality, they are three-dimensional spaces with height. Also, in Figure 3, the detection target range is shown as the building clearance range, so objects detected within the detection target range are obstacles.

[0029] Returning to Figure 2, let D1 be the distance D related to the direct wave from the transmitting position to the receiving position, D2 be the distance D related to the propagation path of the reflected wave without obstacles, and D3 be the distance D related to the propagation path of the reflected wave with obstacles (see Figure 1). Then, as the propagation path transfer function in this situation, Figure 2 shows the frequency spectra (amplitude spectra) for each of the following, from top to bottom: (1) the reference propagation path transfer function, (2) the propagation path transfer function based on the received signal, and (3) the difference between the above propagation path transfer function (2) and the reference propagation path transfer function (1). Furthermore, each propagation path transfer function is shown focusing on one subcarrier frequency f in OFDM.

[0030] As shown in Figure 2(1), the reference path transfer function is the path transfer function when there are no obstacles within the detection range. In this case, since both the direct wave and the reflected wave from the non-obstructed object are received, peaks appear in the frequency spectrum (amplitude spectrum) of the reference path transfer function at frequencies F1 and F2 corresponding to the distances D1 and D2.

[0031] As shown in Figure 2(2), the path transfer function based on the received signal is the path transfer function when an obstacle is present within the detection range. In this case, in addition to the direct wave and the reflected wave from an unobstructed area, the reflected wave from the obstacle within the detection range is also received, so peaks appear in the frequency spectrum (amplitude spectrum) of the path transfer function at frequencies F1, F2, and F3 corresponding to the distances D1, D2, and D3.

[0032] As shown in Figure 2(3), the difference between the propagation path transfer function based on the received signal (2) and the reference propagation path transfer function (1) is obtained by removing the frequency response component for the direct wave and the frequency response component for the reflected wave at an obstacle, which are included in both the propagation path transfer function and the reference propagation path transfer function, from the propagation path transfer function based on the received signal. As a result, the propagation path transfer function consists only of the frequency response component for the reflected wave at an obstacle. Therefore, in the frequency spectrum (amplitude spectrum) of this propagation path transfer function, a peak is observed only at frequency F3, which corresponds to the propagation distance D3, which is the propagation distance of the reflected wave at the obstacle. This peak allows for the detection of the presence of an obstacle.

[0033] Furthermore, the detection range can also be defined as the railway site area including the building clearance (for example, the tracks for both directions) and a certain area above it, thus encompassing a relatively wide area as the detection range for obstacles. In this case, non-obstacles installed at fixed positions, such as signs, will be present within the detection range. However, information (frequency components) regarding reflected waves from these non-obstacles is included in both (1) the reference propagation path transfer function and (2) the propagation path transfer function based on the received signal, and can be removed by calculating the difference.

[0034] Next, consider a situation where a moving object, such as a car, is temporarily within the detectable range but outside the detection range. The reference path transfer function is the path transfer function when there are no obstacles within the detection range. However, since it is pre-prepared comparison criterion data before being used for obstacle detection, it is not data for situations where an object that does not normally exist is present within the detectable range. Therefore, the reference path transfer function is not data for situations where a moving object, such as a car, is temporarily within the detectable range but outside the detection range.

[0035] Therefore, the difference between the propagation path transfer function based on the received signal (corresponding to (2) in Figure 2) and the reference propagation path transfer function (corresponding to (1) in Figure 2) (corresponding to (3) in Figure 2) may include information (frequency components) about reflected waves from non-obstacles outside the detection range but within the detectable range (e.g., moving objects such as automobiles), in addition to obstacles within the detection range, and it is necessary to distinguish between these. This distinction can be made by the estimated relative positions with respect to the transmission position (installation position of transmitter 10) and the reception position (installation position of receiver 20).

[0036] To realize such obstacle detection functions, the signal processing unit 30, as shown in Figure 1, includes an oscillation unit 31, a transmit OFDM signal generation unit 32, an FFT unit 33, a propagation path transfer function calculation unit 34, an obstacle presence / absence determination unit 35, an obstacle position estimation unit 36, and a reference propagation path transfer function update unit 37.

[0037] The oscillator unit 31 is an oscillator that generates an oscillation signal of a predetermined frequency, and outputs the generated oscillation signal to the transmitter 10 and the receiver 20 as a common local oscillation signal (local signal).

[0038] The transmission OFDM signal generation unit 32 generates a transmission OFDM signal by performing OFDM modulation processing, such as IFFT (Inverse Fast Fourier Transform), on arbitrary transmission data and outputs it to the transmitter 10.

[0039] The FFT unit 33 performs frequency analysis on the transmitted signal sent by the transmitter 10 and the received signal received by the receiver 20. In other words, it performs FFT processing, which is a frequency analysis process, on the transmitted OFDM signal (transmitted signal) and the received OFDM signal (received signal) to convert them from time-domain signals to frequency-domain signals.

[0040] The propagation path transfer function calculation unit 34 calculates the propagation path transfer function, which includes the frequency response component related to the propagation path of the reflected wave from the transmitting position to the receiving position, based on the analysis results obtained by frequency analysis of the transmitted signal and the received signal, as the ratio of the frequency components of the transmitted signal and the frequency components of the received signal. In other words, the ratio of the signal obtained by Fourier transform of the received OFDM signal, which is the result of the frequency analysis of the received signal, to the signal obtained by Fourier transform of the transmitted OFDM signal, which is the result of the frequency analysis of the transmitted signal, is calculated as the propagation path transfer function, which is the transfer function of the propagation path from the transmitting position to the receiving position (see Figure 2).

[0041] The obstacle presence / absence determination unit 35 determines the presence or absence of obstacles within the detection range based on the reference propagation path transfer function, which is a comparison criterion for propagation path transfer functions, and the propagation path transfer function. The reference propagation path transfer function is the propagation path transfer function when there are no obstacles within the detection range (see Figure 2).

[0042] The obstacle position estimation unit 36 ​​estimates the position of the obstacle based on the difference between the reference propagation path transfer function and the propagation path transfer function. The position of the obstacle is estimated based on the propagation path distance D and the direction of arrival of the reflected wave from the obstacle. The direction of arrival of the reflected wave from the obstacle is estimated based on frequency components included in the propagation path transfer function that satisfy a predetermined relative amplitude difference condition with respect to the reference propagation path transfer function (see Figure 2).

[0043] The reference propagation path transfer function update unit 37 updates the reference propagation path transfer function using the propagation path transfer function determined by the obstacle presence / absence determination unit 35 to be free of obstacles. The update of the reference propagation path transfer function may be performed, for example, by replacing the existing reference propagation path transfer function with the propagation path transfer function determined to be free of obstacles, by replacing the existing reference propagation path transfer function with the average of multiple propagation path transfer functions determined to be free of obstacles, or by replacing the existing reference propagation path transfer function with the average of the propagation path transfer function determined to be free of obstacles and the existing reference propagation path transfer function.

[0044] [Process Flow] Figure 4 is a flowchart illustrating the flow of the obstacle detection process performed by the signal processing unit 30.

[0045] First, as an initial state, the reference propagation path transfer function update unit 37 performs initial setup of the reference propagation path transfer function (step S1). After that, it transitions to the measurement state. That is, the propagation path transfer function calculation unit 34 calculates the propagation path transfer function based on the transmitted signal and the received signal (step S3). Next, the obstacle presence / absence determination unit 35 determines the presence or absence of obstacles within the detection target range on the trajectory based on the calculated propagation path transfer function. In other words, it calculates the similarity (e.g., correlation value) between the calculated propagation path transfer function and the reference propagation path transfer function (step S5), and if the calculated similarity is above a predetermined threshold (step S7: YES), it determines that there are "no obstacles" (step S9). Then, the reference propagation path transfer function update unit 37 updates the reference propagation path transfer function (step S11).

[0046] On the other hand, if the similarity is below the threshold (step S7: NO), the obstacle presence determination unit 35 determines that there is an obstacle (step S13). Next, the obstacle position estimation unit 36 ​​estimates the position of the obstacle. That is, it calculates the difference between the calculated propagation path transfer function and the reference propagation path transfer function (step S15), and estimates the position of the obstacle based on the calculated difference (step S17).

[0047] After that, it is determined whether or not to terminate obstacle detection. If not to terminate (step S19: NO), the process returns to step S3. If to terminate (step S19: YES), this process is terminated.

[0048] [Effects and Effects] Thus, according to this embodiment, an obstacle detection device 1 with improved detection accuracy can be realized with a simple device configuration. Specifically, it detects obstacles within the detection range on the orbit by transmitting and receiving wireless signals, but the presence or absence of obstacles is determined based on a propagation path transfer function calculated from the analysis results obtained by frequency analysis of the transmitted and received signals, and a reference propagation path transfer function that serves as a comparison standard. The propagation path transfer function includes the frequency response component related to the propagation path of the reflected wave from the transmission position to the reception position. The reference propagation path transfer function is the propagation path transfer function when there are no obstacles within the detection range, and is a propagation path transfer function that can be used as a standard for determining the presence or absence of obstacles. This makes it possible to accurately determine the presence or absence of obstacles within the detection range. Furthermore, since the propagation path transfer function is based on the analysis results obtained by frequency analysis of the transmitted and received signals, the influence of fluctuations in the transmitted signal is small. This further improves the accuracy of determining obstacles within the detection range on the orbit. As described above, it is possible to realize an obstacle detection device that can accurately determine the presence or absence of obstacles within the detection range on the orbit, despite having a simple configuration that involves signal processing of transmitted and received signals.

[0049] It should be noted that the applicable embodiments of the present invention are not limited to those described above, and can be modified as appropriate without departing from the spirit of the invention.

[0050] For example, in the above-described embodiment, the obstacle presence / absence determination unit 35 determines the presence or absence of an obstacle by calculating the similarity between the reference propagation path transfer function and the propagation path transfer function. Alternatively, the presence or absence of an obstacle may be determined using the difference between the reference propagation path transfer function and the propagation path transfer function. In this case, for example, if the difference includes a frequency spectrum with an amplitude greater than or equal to a predetermined amplitude threshold, it is determined that an obstacle is present. [Explanation of symbols]

[0051] 1… Obstacle detection device 10…Transmitter 20... Receiver 30... Signal Processing Unit 31...Oscillator 32...Transmit OFDM signal generation unit 33...FFT section 34…Propagation path transfer function calculation unit 35... Obstacle presence / absence detection unit 36... Obstacle position estimation unit 37…Reference propagation path transfer function update section

Claims

1. An obstacle detection device that detects obstacles by transmitting and receiving wireless signals, A transmission means for transmitting a predetermined transmission signal from a predetermined transmission position, A receiving means that receives at a predetermined receiving location, A calculation means calculates a propagation path transfer function, which includes frequency response components related to the propagation path of the reflected wave from the transmission position to the reception position, based on the analysis results obtained by frequency analysis of the transmission signal and the reception signal of the receiving means. An estimation means for estimating the relative position of the obstacle with respect to the transmitting position and the receiving position, using: 1) the path distance of the reflected wave at the obstacle, based on the peak frequency of the frequency spectrum representing the difference between a reference path transfer function that serves as a comparison standard for the path transfer function and the path transfer function; and 2) the direction of arrival of the reflected wave from the obstacle, based on frequency components included in the path transfer function that satisfy a predetermined relative amplitude difference condition with respect to the reference path transfer function. A determination means that determines whether the obstacle is within the detection range on the trajectory based on the position estimated by the estimation means, An obstacle detection device equipped with [a specific feature].

2. An update means that updates the reference propagation path transfer function using the propagation path transfer function determined by the determination means to be free of obstacles within the detection target range, The obstacle detection device according to claim 1, further comprising:

3. An obstacle detection method that detects obstacles by transmitting and receiving wireless signals, Based on the analysis results obtained by frequency analysis of a predetermined transmitted signal transmitted from a predetermined transmitting position and a predetermined received signal received at a predetermined receiving position, a propagation path transfer function including the frequency response component related to the propagation path of the reflected wave from the time it is transmitted at the transmitting position to the time it is received at the receiving position is calculated. 1) The path distance of the reflected wave at the obstacle, based on the peak frequency of the frequency spectrum representing the difference between the reference path transfer function, which serves as a comparison standard for the path transfer function, and the path transfer function; and 2) The direction of arrival of the reflected wave from the obstacle, based on the frequency components included in the path transfer function that satisfy a predetermined relative amplitude difference condition with respect to the reference path transfer function; and the relative position of the obstacle with respect to the transmission position and the reception position, respectively. Based on the estimated position, it is determined whether the obstacle is within the detection range on the trajectory. An obstacle detection method including the following.

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