An animal detection system for cable trenches based on FMCW radar

Abstract

The present invention relates to an animal detection system for cable trenches based on an FMCW radar, comprising a microprocessor, an FMCW radar, a display screen and a button; the microprocessor controls the FMCW radar to transmit a transmission wave and receive a reflected wave, and analyzes the reflected wave to obtain an animal detection result in the cable trench; the transmission wave is a triangular wave; the display screen is used to display the animal detection result; the button is used to control the microprocessor to perform a specific operation; the FMCW radar is closely attached above the cable trench cover. The present invention detects the objects in the cable trench through continuous triangular radar waves, and obtains the number of animals in the cable trench through low-pass filtering and numerical screening.

Description

Technical Field

[0001] The present invention relates to a cable trench animal detection system based on an FMCW radar, belonging to the technical field of cable trench animal detection. Background Art

[0002] In a substation, electrical equipment such as cables is laid in a cable trench. The cable trench is often dozens or even hundreds of meters long and covered with a cover plate on top. Due to the complex environment, small animals are likely to gnaw on the cables, causing cable damage and unstable power supply. Therefore, it is necessary to periodically detect and remove small animals in the cable trench. The existing operation method is to manually lift the cover plate one by one for inspection. The workload is huge and time-consuming. Although radar can obtain information about animals in the cable trench, the radar signal will be weakened by the front cover plate and cabinets, blocked by obstacles in the space, with large interference and weak reflected waves. It is difficult to obtain information about small animals in the cable trench. Summary of the Invention

[0003] In order to overcome the above problems, the present invention provides a cable trench animal detection system based on an FMCW radar. The animal detection system detects objects in the cable trench through continuous triangular radar waves, and obtains the number of animals in the cable trench through low-pass filtering and numerical screening.

[0004] The technical solution of the present invention is as follows:

[0005] A cable trench animal detection system based on an FMCW radar includes a microprocessor, an FMCW radar, a display screen, and a key; the microprocessor controls the FMCW radar to emit a transmitted wave and receive a reflected wave, and analyzes the reflected wave to obtain an animal detection result in the cable trench; the transmitted wave is a triangular wave; the display screen is used to display the animal detection result; the key is used to control the microprocessor to perform specific operations; the FMCW radar is closely attached above the cable trench cover.

[0006] Further, the analysis includes the following steps:

[0007] Establish a time-frequency diagram of the transmitted wave and the reflected wave according to the transmitted wave and the reflected wave, and mark the triangular vertex of the transmitted wave as N (0)1 , mark n - 1 points on the transmitted wave at intervals of time T1, N (0)2 - N (0)n ; mark the triangular vertex of the k-th reflected wave as N (k)1 , mark n - 1 points on the reflected wave at intervals of time T1, N (k)2 - N (k)n ;

[0008] Obtain the coordinates (X of the m-th point N (k)m of the k-th reflected wave(k)m , Y (k)m );

[0009] Calculate N (k)m The moment M of the point N corresponding to the transmitted wave (0)m is km =(X (k)m - X (0)m ) 2 +(Y (k)m - Y (0)m ) 2 ;

[0010] Construct a matrix

[0011] where j is the number of reflected waves;

[0012] Perform a fast Fourier transform on the matrix M to obtain the matrix

[0013] Perform low-pass filtering on the matrix F to obtain a set of elements F1, F2, F3,..., F P , where p is the number of elements;

[0014] Determine the moments corresponding to the elements F1, F2, F3,..., F P in the matrix M to obtain a set of moments M1, M2, M3,..., M P ;

[0015] Screen out the moments in M1, M2, M3,..., M P that are less than S to obtain another set of moments M'1, M'2, M'3,..., M' q , where q is the number of moments, i.e., the number of animals in the cable trench.

[0016] Furthermore, the duration of the transmitted wave is not less than 5 seconds, each frame of radar wave contains 20 triangular waves, and the interval between two frames is 100 milliseconds.

[0017] Furthermore, the low-pass filtering specifically means screening out the elements in the matrix F that are greater than the threshold K, and the K is the maximum value of the periodic vibration frequency of the animal to be detected.

[0018] Furthermore, the K is 8 - 10.

[0019] Furthermore, the S is determined through experiments. Description of the Drawings

[0020] Figure 1 It is a schematic diagram of the module of the present invention.

[0021] Figure 2 It is a schematic diagram of the working state of the present invention.

[0022] Figure 3 It is the time-frequency diagram of the transmitted wave and the reflected wave of the embodiment of the present invention.

[0023] The reference signs in the figure are represented as:

[0024] 1. Microprocessor; 2. FMCW radar; 3. Display screen; 4. Button. Specific embodiments

[0025] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] Embodiment 1

[0027] Refer to Figure 1 and 2 , a cable trench animal detection system based on an FMCW radar, comprising a microprocessor 1, an FMCW radar 2, a display screen 3 and a button 4; the microprocessor 1 controls the FMCW radar 2 to transmit a transmitted wave and receive a reflected wave, and analyzes the reflected wave to obtain an animal detection result in the cable trench; the transmitted wave is a triangular wave; the display screen 3 is used to display the animal detection result; the button 4 is used to control the microprocessor 1 to perform a specific operation; the FMCW radar 2 is closely attached above the cable trench cover.

[0028] Embodiment 2

[0029] Refer to Figure 3 , for the cable trench animal detection system based on the FMCW radar, on the basis of Embodiment 1, the analysis includes the following steps:

[0030] Establish a time-frequency diagram of the transmitted wave and the reflected wave according to the transmitted wave and the reflected wave, and calibrate the triangular vertex of the transmitted wave as N (0)1 , calibrate n-1 points on the transmitted wave at intervals of time T1, N (0)2 -N (0)n ; calibrate the triangular vertex of the kth reflected wave as N (k)1 , calibrate n-1 points on the reflected wave at intervals of time T1, N (k)2 -N (k)n ;

[0031] Obtain the coordinates (X (k)m , Y (k)m ) of the mth point N (k)m of the kth reflected wave;

[0032] Calculate the moment M (k)m of N (0)m and the corresponding point N km of the transmitted wave = (X (k)m -X (0)m )2 +(Y (k)m -Y (0)m ) 2 ;

[0033] Construct a matrix

[0034] where j is the number of reflected waves;

[0035] Perform a fast Fourier transform on the matrix M to obtain the matrix After the fast Fourier transform, the matrix changes the time-domain signal to a frequency-domain signal;

[0036] Perform low-pass filtering on the matrix F to obtain a set of elements F1, F2, F3, ……, F P , where p is the number of elements; low-pass filtering can remove elements with higher frequencies to prevent being misidentified as animals due to some disturbances in the actual scenario.

[0037] Determine the moments corresponding to the elements F1, F2, F3, ……, F P in the matrix M to obtain a set of moments M1, M2, M3, ……, M P ;

[0038] Screen out the moments in M1, M2, M3, ……, M P that are less than S to obtain another set of moments M'1, M'2, M'3, ……, M' q , where q is the number of moments, that is, the number of animals in the cable trench.

[0039] Furthermore, the duration of the transmitted wave is not less than 5 seconds, each frame of radar wave contains 20 triangular waves, and the interval between two frames is 100 milliseconds.

[0040] Furthermore, the low-pass filtering specifically means screening out the elements in the matrix F that are greater than the threshold K, and the K is the maximum value of the periodic vibration frequency of the animal to be detected. In order to avoid disturbances in the scenario being misidentified as animals, when screening out the disturbance elements, the maximum value of the periodic vibration frequency of the animal to be detected is used as the threshold. This value can be obtained through experiments.

[0041] Furthermore, the K is 8 - 10. The animals in the cable trench are generally mice, and the maximum value of the periodic vibration frequency of mice is the mouse's heartbeat. The mouse's heartbeat is between 8 - 10.

[0042] Furthermore, the value of S is determined through experiments. S is the sum of the squares of the Doppler effect Δf generated by the minimum value of the animal's movement speed in the average state on the radar wave frequency and the minimum value of the movement amplitude Δl within a triangular wave frequency modulation period. Due to the uncertainty of the animal's movement speed, the value of S in different animal movement states can be determined through experiments. And this value of S is stored in the system to detect animals in different movement states.

[0043] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structures made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, are similarly included in the patent protection scope of the present invention.

Claims

1. A cable trench animal detection system based on FMCW radar, characterized in that, It includes a microprocessor (1), an FMCW radar (2), a display screen (3), and a button (4); the microprocessor (1) controls the FMCW radar (2) to emit transmitted waves and receive reflected waves, and analyzes the reflected waves to obtain the animal detection result in the cable trench; the transmitted wave is a triangular wave; the display screen (3) is used to display the animal detection result; the button (4) is used to control the microprocessor (1) to perform specific operations; the FMCW radar (2) is closely attached above the cable trench cover; The analysis includes the following steps: Establish a time-frequency diagram of the transmitted wave and the reflected wave based on the transmitted wave and the reflected wave, and mark the triangular vertex of the transmitted wave as N (0)1 , mark n - 1 points on the transmitted wave at intervals of time T1, N (0)2 -N (0)n ; mark the triangular vertex of the k-th reflected wave as N (k)1 , mark n - 1 points on the reflected wave at intervals of time T1, N (k)2 -N (k)n ; Obtain the coordinates (X (k)m , Y (k)m , (k)m ) of the m-th point N of the k-th reflected wave; Calculate N (k)m The moment M of the point N corresponding to the emission wave (0)m is km =(X (k)m - X (0)m ) 2 +(Y (k)m - Y (0)m ) 2 ; Construct a matrix where j is the number of reflected waves; Perform a fast Fourier transform on the matrix M to obtain the matrix Perform low-pass filtering on the matrix F to obtain a set of elements F1, F2, F3, ……, F P , where p is the number of elements; Determine elements F1, F2, F3, ……, F P Obtain corresponding moments in the matrix M, resulting in a set of moments M1, M2, M3, ……, M P ; Screen out moments M1, M2, M3, ……, M P in P that are less than S to obtain another set of moments M'1, M'2, M'3, ……, M' q , where q is the number of moments, i.e., the number of animals in the cable trench, and S is the sum of the squares of the Doppler effect generated by the minimum animal movement speed in the average state on the radar wave frequency and the minimum movement amplitude within a triangular wave frequency modulation period.

2. The cable trench animal detection system based on the FMCW radar according to claim 1, wherein The duration of the transmitted wave is not less than 5 seconds, each frame of radar wave contains 20 triangular waves, and the interval between two frames is 100 milliseconds.

3. The cable trench animal detection system based on the FMCW radar according to claim 1, characterized in that The low-pass filtering specifically screens out the elements in matrix F that are greater than the threshold K, and K is the maximum value of the periodic vibration frequency of the animal to be detected.

4. The cable trench animal detection system based on FMCW radar according to claim 1, characterized in that, K is 8 - 10.

5. The cable trench animal detection system based on the FMCW radar according to claim 1, characterized in that S is determined through experiments.

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