JP2023160504A - Obstacle detection device and obstacle detection method - Google Patents

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

The present invention relates to an obstacle detection device and the like that detect obstacles on a track.

In railways, the introduction of automatic train operation control requires technology to detect obstacles on the tracks and stop trains as necessary to prevent accidents. Technologies for detecting obstacles on tracks include, for example, a technology that installs a detection device that integrates a radar device and a reflector on the ground (for example, see Patent Document 1), and a technology that installs a detection device that integrates a radar device and a reflector (reflector) on the ground, There is a known technology (for example, see Patent Document 2) in which a millimeter wave radar is mounted on a device (above).

Japanese Patent Application Publication No. 2018-144505 Japanese Patent Application Publication No. 2015-034793

From the viewpoint of safety, obstacle detection devices are required to further improve their detection accuracy. In addition, since the track is long and there are many trains running on the track, a large number of detection devices are required.In order to reduce the cost of installing and maintaining the detection device, a simple device configuration is required. It is also required.

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

The first invention for solving the above problem is:
An obstacle detection device that transmits and receives radio signals to detect obstacles within a detection target range on orbit,
Transmitting means (for example, transmitter 10 in FIG. 1) that transmits a predetermined transmission signal from a predetermined transmission position;
Receiving means for receiving at a predetermined receiving position (for example, receiver 20 in FIG. 1);
Based on the analysis results of frequency analysis of the transmitted signal and the received signal of the receiving means, the propagation includes a frequency response component related to the propagation path of the reflected wave from being transmitted at the transmitting position to being received at the receiving position. a calculation means for calculating a channel transfer function (for example, the channel transfer function calculation unit 34 in FIG. 1);
Judgment means (for example, the obstacle shown in FIG. Presence/absence determination section 35);
This is an obstacle detection device equipped with.

Other inventions include
An obstacle detection method for detecting obstacles within a detection target range on orbit by transmitting and receiving radio signals, the method comprising:
Based on the results of frequency analysis of a predetermined transmission signal transmitted from a predetermined transmission position and a reception signal received at a predetermined reception position, the signal is transmitted at the transmission position and then received at the reception position. calculating a propagation path transfer function including a frequency response component related to the propagation path of the reflected wave up to (for example, step S3 in FIG. 4);
Determining the presence or absence of the obstacle within the detection target range based on the propagation path transfer function and a reference propagation path transfer function that is a comparison standard for the propagation path transfer function (for example, from step S5 in FIG. 4). S9, S11) and
An obstacle detection method including:

According to the first aspect of the invention, an obstacle detection device with improved detection accuracy can be realized with a simple device configuration. In other words, obstacles within the detection range on the orbit are detected by transmitting and receiving radio signals, but the propagation path transfer is calculated based on the analysis results of frequency analysis of the transmitted and received signals. This is performed based on the function and a reference propagation path transfer function that serves as a comparison standard. The propagation path transfer function includes a frequency response component related to the propagation path of the reflected wave from transmission at the transmission position to reception at the reception position. The reference propagation path transfer function can be, for example, a propagation path transfer function that can be used as a reference for determining the presence or absence of an obstacle, such as a propagation path transfer function in a situation where there is no obstacle within the detection target range. This makes it possible to accurately determine the presence or absence of an obstacle within the detection target range. Furthermore, since the propagation path transfer function is based on the analysis results of frequency analysis of the transmitted signal and the received signal, the influence of fluctuations in the transmitted signal is small. This point further improves the accuracy of determining obstacles within the detection target range on the orbit. As described above, according to the first invention, etc., it is possible to accurately determine the presence or absence of an obstacle within the detection target range on the orbit, even though it has a simple configuration in which the transmitted signal and the received signal are processed. becomes.

The second invention is, in the first invention,
The calculating means calculates the propagation path transfer function as a ratio of a frequency component of the transmitted signal and a frequency component of the received signal,
Estimating means for estimating the position of the obstacle based on the difference between the reference propagation path transfer function and the propagation path transfer function (for example, the obstacle position estimating unit 36 in FIG. 1);
An obstacle detection device further comprising:

According to the second invention, the position of the obstacle can be estimated based on the difference between the reference channel transfer function and the channel transfer function. The reference propagation path transfer function is a propagation path transfer function that can be used as a standard for determining the presence or absence of an obstacle, such as a propagation path transfer function in a situation where there is no obstacle within the detection target range. It can be determined that the difference between and the propagation path transfer function corresponds to the frequency component of the reflected wave from the obstacle within the detection target range. In this way, based on the difference between the reference propagation path transfer function and the propagation path transfer function, it is possible to accurately estimate the position of the obstacle.

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

According to the third invention, the direction of arrival of the reflected wave from the obstacle is estimated based on a frequency component that satisfies a predetermined amplitude relative difference condition with respect to a reference propagation path transfer function included in the propagation path transfer function. I can do it. By using the frequency component that satisfies a predetermined amplitude relative difference condition with respect to the reference propagation path transfer function included in the propagation path transfer function, it becomes possible, for example, to extract only the frequency component of the reflected signal from an obstacle. Based on the frequency components, it is possible to accurately estimate the arrival direction of the reflected wave from the obstacle, that is, the direction of the obstacle. Further, the propagation path transfer function includes a frequency response component related to the propagation path of the reflected wave. Therefore, from the magnitude of the amplitude (reception intensity) of the reflected wave, it is possible to determine the distance from the transmission position to the obstacle to the reception position, which is the propagation path of the radio signal related to the reflected wave. Therefore, it is also possible to estimate the position of the obstacle from these.

The fourth invention is any one of the first to third inventions,
updating means for updating the reference propagation path transfer function using the propagation path transfer function determined to be free of obstacles by the determination means (for example, the reference propagation path transfer function updating unit 37 in FIG. 1);
An obstacle detection device further comprising:

According to the fourth invention, it is possible to further improve the accuracy of detecting obstacles. That is, since the environment along the railway can change over time, the received signal can change even if there are no obstacles within the detection target range, and as a result, the propagation path transfer function can also change. Therefore, by updating the standard propagation path transfer function using the propagation path transfer function that has been determined to be free of obstacles, the standard propagation path transfer function can be made to reflect the latest environment, and the obstacle detection accuracy can be improved. This makes it possible to improve the

Application example of obstacle detection device. An explanatory diagram of obstacle detection. An explanatory diagram of a detection target range. Flowchart of obstacle detection processing.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. Note that the form to which the present invention can be applied is not limited to the following embodiments. In addition, in the description of the drawings, the same elements are given the same reference numerals.

[overall structure]
FIG. 1 is an example of application of the obstacle detection device in this embodiment. The obstacle detection device 1 is a device that transmits and receives wireless signals to detect obstacles within a detection target range on an orbit, and includes a transmitter 10, a receiver 20, and a signal processing section 30. For example, the detection target range may include a railroad crossing, a track beside a platform, or a track in a mountainous area where falling rocks or avalanches may occur. can do.

The transmitter 10 is installed near the orbit, and transmits a radio signal from a directional antenna toward a detection target range on the orbit. That is, the transmission OFDM (Orthogonal Frequency Division Multiplexing) signal input from the transmission OFDM signal generation section 32 of the signal processing section 30 is used as the oscillation signal input from the oscillation section 31 of the signal processing section 30. By performing orthogonal modulation processing, it is converted into a radio frequency signal (radio signal) and transmitted.

The receiver 20 is installed along the orbit, and receives radio signals including reflected signals from the detection target range on the orbit using a directional antenna. That is, a received radio signal (received signal) is converted into a received OFDM signal by performing orthogonal demodulation processing using an oscillation signal input from the oscillation unit 31 of the signal processing unit 30, and output to the signal processing unit 30. do.

The signal processing unit 30 determines the presence or absence of obstacles within the detection target range on the orbit based on the transmission signal (radio signal) transmitted by the transmitter 10 and the reception signal (radio signal) received by the receiver 20. If it is determined that there is an obstacle, the location of the obstacle is estimated.

Detection of an obstacle by the signal processing unit 30 (determining the presence or absence of an obstacle and estimating the position of the obstacle) will be described. Obstacle detection is performed using a propagation path transfer function based on the results of frequency analysis of the transmitted signal and the received signal. The propagation path transfer function includes a frequency response component related to the propagation path of the reflected wave from when it is transmitted at the transmission position (the installation position of the transmitter 10) until it is received at the reception position (the installation position of the receiver 20). It is calculated as the ratio of the frequency component of the transmitted signal and the frequency component of the received signal. In this embodiment, FFT (Fast Fourier Transformation) is performed as frequency analysis. Therefore, the propagation path transfer function regarding the propagation path of the radio signal from the transmission position (the installation position of the transmitter 10) to the reception position (the 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, in the frequency spectrum (amplitude spectrum) representing this propagation path transfer function, there is a peak at the frequency F (=distance D/wavelength λ) corresponding to the distance D of the propagation path. arise. Further, the peak value becomes the amplitude A in equation (1) of the propagation path transfer function. The distance D includes, for example, the distance D1 of a direct wave in FIG. 1, and the distances D2 and D3 of reflected waves (indirect waves) reflected by some object.

The presence or absence of an obstacle is determined based on this propagation path transfer function and a reference propagation path transfer function serving as a comparison standard. The reference propagation path transfer function is a propagation path transfer function in a situation where there is no obstacle within the detection target range. However, as a propagation path from the transmitting position to the receiving position of the wireless signal, in addition to the path in which the direct wave from the transmitting position is received at the receiving position, there is also a path in which reflected waves (indirect waves) reflected from some object including the ground are received. Includes routes to Therefore, even if the reference propagation path transfer function is a propagation path transfer function in a situation where there is no obstacle within the detection target range, it may include some indirect waves in addition to the direct waves. Therefore, in order to determine the presence or absence of an obstacle, in this embodiment, a correlation value is obtained as the degree of similarity between the propagation path transfer function and the reference propagation path transfer function, and if the obtained correlation value is equal to or greater than a predetermined threshold, it is determined that there is no obstacle. ”, and if it is less than the threshold, it is determined that “an obstacle is present”.

Note that the propagation path transfer function and the similarity are repeatedly calculated at predetermined time intervals, and the state in which the similarity is greater than or equal to a predetermined threshold continues for a predetermined number of times (for example, 3 times) or for a predetermined time (for example, 5 seconds) or more. In this case, it may be determined that there is no obstacle, and when the state where the value is less than the threshold continues for a predetermined number of times or for a predetermined period of time, it may be determined that there is an obstacle. Alternatively, to calculate the similarity, machine learning may be performed to calculate the similarity using a reference channel transfer function as training data, and the obtained new channel transfer function may be input to calculate the similarity. .

If it is determined that "an obstacle is present", the position of the obstacle is further estimated based on the difference between the propagation path transfer function and the reference propagation path transfer function. Since the reference propagation path transfer function is the propagation path transfer function in a situation where there is no obstacle within the detection target range, the difference between the propagation path transfer function and the reference propagation path transfer function is the one in which there is an obstacle within the detection target range. It can be said that this is the frequency response component of the reflected wave from the Therefore, 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, - Find the distance D of the propagation path of the radio signal (indirect wave) related to the reflected wave up to the reception position (installation position of the receiver 20). The distance D at this time is the distance D3 in FIG. Further, the difference between the propagation path transfer function and the reference propagation path transfer function is based on the result of FFT processing of the transmitted signal and the received signal as frequency analysis processing, and includes information on the amplitude and phase of each frequency. Therefore, the direction of arrival of the reflected wave from the obstacle is estimated by using the direction of arrival estimation algorithm, such as the MUSIC algorithm or the ESPRIT algorithm. From the distance D and arrival direction determined above, the position of the obstacle relative to the transmission position (installation position of the transmitter 10) and reception position (installation position of the receiver 20) is estimated.

Note that since the environment along the track, including objects around the orbit, may change over time, the received signal may also change, and as a result, the propagation path transfer function may also change. Therefore, the arrival direction of the reflected wave from the obstacle is estimated based on the frequency component that satisfies a predetermined amplitude relative difference condition with respect to the reference channel transfer function included in the channel transfer function. That is, the direction of arrival of the reflected wave from the obstacle is estimated based on the frequency component whose amplitude relative difference is greater than or equal to a predetermined value in the difference between the propagation path transfer function and the reference propagation path transfer function.

FIG. 2 is a diagram illustrating an example of obstacle detection based on a propagation path transfer function. In order to make the explanation easier to understand, Figure 2 shows a direct wave from the transmitting position to the receiving position, and a reflected wave from a non-obstacle (an object that is not an obstacle) that is within the detectable range but outside the detection target range. The following description will be made assuming that three signals are received: a wave reflected from an obstacle within the detectable range, and a reflected wave from an obstacle within the detection target range.

Here, the detectable range and the detection target range will be explained with reference to FIG. 3. FIG. 3 is a diagram illustrating the detection target range of the obstacle detection device 1. FIG. 3 shows a schematic top view of the track looking down from above. The detection target range is a preset range in which obstacles are to be detected, and is defined as a predetermined range on the orbit. The detection range can be arbitrarily set, and by setting it as the building limit range, objects detected within the detection range can be recognized as obstacles.

The detectable range is the range in which the presence of some object can be detected by radio signals sent and received by the directional antennas of the transmitter 10 and the receiver 20, and the detectable range is the range where the presence of some object can be detected. This range is determined by attitude, communication performance, etc. The transmitter 10 and the receiver 20 are designed, set, and installed so that the detectable range includes the detection target range. Although the detection target range and the detectable range are shown as two-dimensional ranges in FIG. 3, they are actually three-dimensional spaces with height. Moreover, in FIG. 3, since the detection target range is shown as a building limit range, the object detected in the detection target range is an obstacle.

Returning to Figure 2, the distance D related to the direct wave from the transmitting position to the receiving position is D1, the distance D related to the propagation path of the reflected wave at non-obstacles is D2, and the distance related to the propagation path of the reflected wave at obstacles Let D be D3 (see Figure 1). The propagation path transfer functions in this situation are, in order from the top of FIG. The frequency spectrum (amplitude spectrum) for each of the functions and (1) the difference from the reference propagation path transfer function is shown. Moreover, each propagation path transfer function is shown focusing on one subcarrier frequency f in OFDM.

As shown in (1) of FIG. 2, the reference propagation path transfer function is a propagation path transfer function in a situation where no obstacle exists within the detection target range. In this case, since direct waves and reflected waves from non-obstacles are received, peaks occur at frequencies F1 and F2 corresponding to distances D1 and D2 in the frequency spectrum (amplitude spectrum) of the reference channel transfer function. ing.

As shown in (2) of FIG. 2, the propagation path transfer function based on the received signal is a propagation path transfer function in a situation where an obstacle exists within the detection target range. In this case, in addition to the direct wave and the reflected wave from non-obstacles, reflected waves from obstacles within the detection target range are received, so in the frequency spectrum (amplitude spectrum) of the propagation path transfer function, the distance D1 , D2, and D3, peaks occur at frequencies F1, F2, and F3.

As shown in (3) of FIG. 2, the difference between the above (2) channel transfer function based on the received signal and (1) the reference channel transfer function is calculated from the channel transfer function based on the received signal. The frequency response components for direct waves and the frequency response components for reflected waves at non-obstacles, which are commonly included in the propagation path transfer function and the reference propagation path transfer function, are deleted, and the frequency response components for reflected waves at obstacles are deleted. It becomes the propagation path transfer function of only the frequency response component of . Therefore, in the frequency spectrum (amplitude spectrum) of this propagation path transfer function, a peak occurs only at the frequency F3 corresponding to the distance D3, which is the propagation distance of the wave reflected by the obstacle. This peak allows the presence of an obstacle to be detected.

Note that the detection target range may be a railway site range including the building limit range (for example, up and down tracks) and a certain area above the railway site, and a somewhat wide range can be collectively set as the obstacle detection target range. In this case, a non-obstructive object installed at a fixed position such as a sign exists within the detection target range, but the information (frequency component) regarding the reflected wave from this non-obstructive object is based on (1) the standard Since it is included in both the propagation path transfer function and (2) the propagation path transfer function based on the received signal, it is deleted by calculating the difference.

Next, consider a situation in which a moving object, such as a car, is outside the detection target range but temporarily within the detectable range. The reference propagation path transfer function is a propagation path transfer function in a situation where there are no obstacles within the detection target range, but it is comparison standard data that is prepared in advance before being used for detecting obstacles. , it is not data when an object that does not normally exist exists within the detectable range. Therefore, the reference propagation path transfer function is not data for a situation where a moving object such as a car is outside the detection target range but temporarily exists within the detectable range.

Therefore, the difference (corresponding to (3) in FIG. 2) between the propagation path transfer function based on the received signal (corresponding to (2) in FIG. 2) and the reference propagation path transfer function (corresponding to (1) in FIG. 2) In addition to obstacles within the detection target range, information (frequency components) regarding reflected waves from non-obstacles (for example, moving objects such as cars) outside the detection target range and within the detectable range is included. It is necessary to distinguish between This distinction can be made based on the estimated relative position to the transmitting position (installation position of the transmitter 10) and the receiving position (installation position of the receiver 20).

In order to realize the function related to detecting such an obstacle, the signal processing section 30 includes an oscillation section 31, a transmission OFDM signal generation section 32, an FFT section 33, and a propagation path transfer function, as shown in FIG. It has a function calculation section 34, an obstacle presence/absence determination section 35, an obstacle position estimation section 36, and a reference propagation path transfer function updating section 37.

The oscillator 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).

The transmission OFDM signal generation unit 32 generates a transmission OFDM signal by performing IFFT (Inverse fast Fourier transform) processing, which is OFDM modulation processing, on arbitrary transmission data, and outputs it to the transmitter 10. do.

The FFT unit 33 performs frequency analysis on the transmission signal transmitted by the transmitter 10 and the reception signal received by the receiver 20. That is, FFT processing, which is frequency analysis processing, is performed on the transmission OFDM signal, which is a transmission signal, and the reception OFDM signal, which is a reception signal, to convert a time domain signal into a frequency domain signal.

The propagation path transfer function calculation unit 34 calculates a frequency response component related to the propagation path of the reflected wave from being transmitted at the transmitting position to being received at the receiving position, based on the analysis results of frequency analysis of the transmitted signal and the received signal. The included propagation path transfer function is calculated as a ratio between the frequency component of the transmitted signal and the frequency component of the received signal. In other words, the ratio of the Fourier-transformed signal of the received OFDM signal, which is the analysis result of the frequency analysis of the received signal, to the Fourier-transformed signal of the transmitted OFDM signal, which is the analysis result of the frequency analysis of the transmitted signal, from the transmitting position to the receiving position. It is calculated as a propagation path transfer function, which is a transfer function of the propagation path (see FIG. 2).

The obstacle presence/absence determination unit 35 determines the presence or absence of an obstacle within the detection target range based on a reference propagation path transfer function and a propagation path transfer function that are comparison standards for propagation path transfer functions. The reference propagation path transfer function is a propagation path transfer function when there is no obstacle within the detection target range (see FIG. 2).

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

The reference propagation path transfer function updating section 37 updates the reference propagation path transfer function using the propagation path transfer function determined by the obstacle presence/absence determining section 35 to be free of obstacles. The reference propagation path transfer function may be updated, for example, by replacing the propagation path transfer function when it is determined that there is no obstacle with the existing reference propagation path transfer function, or by replacing the propagation path transfer function when it is determined that there is no obstacle, or by replacing the propagation path transfer function when it is determined that there is no obstacle. This can be done by replacing the average of the propagation path transfer functions of This may be done by replacing the existing reference propagation path transfer function.

[Processing flow]
FIG. 4 is a flowchart illustrating the flow of obstacle detection processing performed by the signal processing unit 30.

First, as an initial state, the reference channel transfer function updating unit 37 initializes the reference channel transfer function (step S1). After that, the state shifts 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 determining unit 35 determines the presence/absence of an obstacle within the detection target range on the orbit based on the calculated propagation path transfer function. That is, the similarity (for example, correlation value) between the calculated propagation path transfer function and the reference propagation path transfer function is calculated (step S5), and if the calculated similarity is greater than or equal to a predetermined threshold (step S7: YES). , it is determined that there is no obstacle (step S9). Then, the reference channel transfer function updating unit 37 updates the reference channel transfer function (step S11).

On the other hand, if the similarity is less than the threshold (step S7: NO), the obstacle presence/absence determining unit 35 determines that "an obstacle is present" (step S13). Next, the obstacle position estimation unit 36 estimates the position of the obstacle. That is, the difference between the calculated propagation path transfer function and the reference propagation path transfer function is calculated (step S15), and the position of the obstacle is estimated based on the calculated difference (step S17).

Thereafter, it is determined whether or not to end the obstacle detection, and if it is not ended (step S19: NO), the process returns to step S3. If it ends (step S19: YES), this process ends.

[Effect]
In this way, according to the present embodiment, the obstacle detection device 1 with improved detection accuracy can be realized with a simple device configuration. In other words, obstacles within the detection range on the orbit are detected by transmitting and receiving radio signals, but the propagation path transfer is calculated based on the analysis results of frequency analysis of the transmitted and received signals. This is performed based on the function and a reference propagation path transfer function that serves as a comparison standard. The propagation path transfer function includes a frequency response component related to the propagation path of the reflected wave from transmission at the transmission position to reception at the reception position. The reference propagation path transfer function is a propagation path transfer function in a situation where there is no obstacle within the detection target range, and is a propagation path transfer function that can be used as a reference for determining the presence or absence of an obstacle. This makes it possible to accurately determine the presence or absence of an obstacle within the detection target range. Furthermore, since the propagation path transfer function is based on the analysis results of frequency analysis of the transmitted signal and the received signal, the influence of fluctuations in the transmitted signal is small. This point further improves the accuracy of determining obstacles within the detection target range on the orbit. As described above, it is possible to realize an obstacle detection device that accurately determines the presence or absence of an obstacle within the detection target range on orbit, even though it has a simple configuration that processes transmitted signals and received signals. .

Note that the applicable embodiments of the present invention are not limited to the above-described embodiments, and of course can be modified as appropriate without departing from the spirit of the present invention.

For example, in the embodiment described above, the obstacle presence/absence determining unit 35 determines the presence or absence of an obstacle by calculating the degree of similarity between the reference propagation path transfer function and the propagation path transfer function. This may be done by determining the presence or absence of an obstacle 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 having an amplitude greater than or equal to a predetermined amplitude threshold, it is determined that an obstacle is present.

1...Obstacle detection device 10...Transmitter 20...Receiver 30...Signal processing section 31...Oscillation section 32...Transmission OFDM signal generation section 33...FFT section 34...Propagation path transfer function calculation section 35...Obstacle presence/absence determination section 36 ...Obstacle position estimation unit 37...Reference propagation path transfer function update unit

Claims (5)

An obstacle detection device that transmits and receives radio signals to detect obstacles within a detection target range on orbit,
Transmitting means for transmitting a predetermined transmission signal from a predetermined transmission position;
a receiving means for receiving at a predetermined receiving position;
Based on the analysis result of frequency analysis of the transmitted signal and the received signal of the receiving means, the propagation includes a frequency response component related to the propagation path of the reflected wave from being transmitted at the transmitting position to being received at the receiving position. calculation means for calculating a path transfer function;
determining means for determining the presence or absence of the obstacle within the detection target range based on the propagation path transfer function and a reference propagation path transfer function that is a comparison standard for the propagation path transfer function;
Obstacle detection device equipped with. The calculating means calculates the propagation path transfer function as a ratio of a frequency component of the transmitted signal and a frequency component of the received signal,
Estimating means for estimating the position of the obstacle based on the difference between the reference propagation path transfer function and the propagation path transfer function;
The obstacle detection device according to claim 1, further comprising: The estimating means estimates the arrival direction of the reflected wave from the obstacle based on a frequency component that satisfies a predetermined amplitude relative difference condition with respect to the reference propagation path transfer function included in the propagation path transfer function.
The obstacle detection device according to claim 2. updating means for updating the reference propagation path transfer function using the propagation path transfer function determined to be free of obstacles by the determination means;
The obstacle detection device according to any one of claims 1 to 3, further comprising: An obstacle detection method for detecting obstacles within a detection target range on orbit by transmitting and receiving radio signals, the method comprising:
Based on the results of frequency analysis of a predetermined transmission signal transmitted from a predetermined transmission position and a reception signal received at a predetermined reception position, the signal is transmitted at the transmission position and then received at the reception position. calculating a propagation path transfer function including a frequency response component related to the propagation path of the reflected wave up to;
Determining the presence or absence of the obstacle within the detection target range based on a reference propagation path transfer function and the propagation path transfer function that serve as a comparison standard for the propagation path transfer function;
Obstacle detection method including.

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