Rockfall monitoring and early warning method based on millimeter wave radar

Abstract

The application discloses a rockfall monitoring and early warning method based on a millimeter wave radar, which comprises the following steps: S1, measuring the position information of an object at three points A, B and C through the millimeter wave radar; S2, calculating the horizontal speed of the object from the point A to the point B and the horizontal speed of the object from the point B to the point C through the position information, and if the horizontal speed of the object from the point A to the point B is equal to the horizontal speed of the object from the point B to the point C, executing step S3; S3, calculating the initial vertical speed of the object from the point A to the point B and the initial vertical speed of the object from the point A to the point C through the position information, and if the initial vertical speed of the object from the point A to the point B is equal to the initial vertical speed of the object from the point A to the point C, judging that the object is a rockfall and issuing a warning. Compared with the prior art, the application can quickly identify the rockfall.

Description

Technical Field

[0001] This invention relates to the field of highway early warning technology, and in particular to a method for monitoring and warning of falling rocks based on millimeter-wave radar. Background Technology

[0002] Millimeter-wave radar, with its active microwave detection physical characteristics, demonstrates significant technological advantages in slope deformation monitoring. Its operating frequency band (typically 24 GHz, 77 GHz, or higher) provides millimeter-level or even sub-millimeter-level displacement measurement accuracy, enabling it to keenly capture phase difference changes at reflection points on the slope surface. This allows it to provide high temporal resolution and high spatial density deformation field data during the early stages of slope deformation—the creep acceleration period. However, when the monitoring scenario shifts from "large-area overall slope displacement" to "local rockfall projection," the applicability of millimeter-wave radar faces severe challenges. The core difficulty in rockfall monitoring lies in target detection and trajectory tracking, rather than static deformation accumulation. This scenario shift exposes radar to strong interference from "non-cooperative targets."

[0003] First, the strong clutter effect caused by vegetation cover. Slope surfaces are usually covered with shrubs, trees, or herbaceous plants. Under the influence of wind, the branches and leaves will sway randomly at the centimeter or even decimeter level. This swaying has spectral overlap with the vibration frequency and micro-Doppler characteristics of the initial stage of rockfall, which can easily be misidentified by radar as a moving target, thus triggering a large number of false alarms.

[0004] Second, the Doppler similarity of biological targets such as birds and insects. When rocks fall freely or roll and impact a slope, their velocity, acceleration, and radar cross-section (RCS) curves overlap in parameter space with the behavior of birds in flight and large insects crossing beams. Existing constant false alarm rate (CFAR) detection algorithms and short-time Fourier transform (STFT) time-frequency analysis methods are still insufficient to construct an effective feature separation hyperplane, leading to frequent false alarms triggered when birds fly overhead. Summary of the Invention

[0005] This invention provides a method for monitoring and warning of falling rocks based on millimeter-wave radar, in order to solve the problem that millimeter-wave radar is easily misled by vegetation and birds when monitoring falling rocks.

[0006] This invention provides a method for monitoring and warning of falling rocks based on millimeter-wave radar, comprising the following steps:

[0007] S1: The position information of the object in the monitoring area at three points A, B, and C is measured by millimeter-wave radar. The position information includes: horizontal position, height position, and time point.

[0008] S2: Calculate the horizontal velocity of the object from point A to point B using the location information. Calculate the horizontal velocity of the object from point B to point C. If horizontal speed equal to horizontal speed If the object is not a falling rock, then proceed to step S3; otherwise, determine that the object is not a falling rock and do not issue a warning.

[0009] S3: Calculate the initial vertical velocity of the object when it reaches point B from point A using the position information. Calculate the initial vertical velocity of the object when it reaches point C from point A. ,if and If the values ​​are equal, the object is identified as a falling rock, and a warning is issued; otherwise, the object is identified as something else, and no warning is issued.

[0010] Preferably, in step S3, after the warning is issued, step S4 is further included, which includes: turning on the vehicle detection radar, and turning on the warning light if a vehicle is detected approaching.

[0011] Preferably, in step S1, the millimeter-wave radar measures the position information of the object at three points A, B, and C using an equal time difference method.

[0012] Preferably, in step S2, the horizontal velocity It is calculated using the following formula:

[0013]

[0014] in, and These represent the horizontal positions of the object at points A and B, respectively. and These are the time points when the object is at point A and point B, respectively.

[0015] Preferably, in step S2, the horizontal velocity It is calculated using the following formula:

[0016]

[0017] in, Let C be the horizontal position of the object. The time point is when the object is at point C.

[0018] Preferably, in step S3, It is calculated using the following formula:

[0019] =

[0020] in, and These represent the height positions of the object at points A and B, respectively. The acceleration due to gravity (approximately 9.8 m / s²) 2 );

[0021] It is calculated using the following formula:

[0022] =

[0023] in, Let C be the height of the object at point C.

[0024] Preferably, in step S2, if > ,and and If the difference is within the predetermined range, the object is judged to be a falling rock, and step S3 is executed; otherwise, the object is judged not to be a falling rock, and no warning is issued.

[0025] Preferably, in step S1, the location information is obtained through the following steps:

[0026] The x, y, and z coordinates of an object at time t are measured and calculated using millimeter-wave radar. The z coordinate represents the object's height, while the x and y coordinates represent the object's horizontal position.

[0027] Preferably, in step S2, the horizontal position of the object at point A The coordinates are (X1, Y1), and the horizontal position of the object at point B is... The coordinates are (X2, Y2), and the horizontal position of the object at point C is... If the coordinates are (X3, Y3), then

[0028] =

[0029] = .

[0030] Preferably, the millimeter-wave radar, vehicle detection radar, and warning light are mounted on the tower.

[0031] Compared with existing technologies, this invention selects the positional information of three points when an object is moving from the collected data. Then, it initially determines whether it is a falling rock based on the horizontal velocity, and confirms that the rock did not reach the ground when the three positional information points were collected. Based on this, it further determines whether it is a falling rock by using the initial vertical velocity. This invention utilizes the characteristic that falling rocks are only affected by gravity during their movement and the small time difference of millimeter-wave radar acquisition, which minimizes the impact of external forces on the horizontal velocity of the falling rock, to monitor falling rocks. The overall structure is simple, it can quickly identify and warn of falling rocks, has good monitoring performance, effectively filters interference from birds, vehicles, pedestrians, and vegetation, and is unaffected by weather and optical conditions, providing safety assurance for traffic and production activities. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0033] Figure 1 This is a flowchart of the process of the present invention;

[0034] Figure 2 This is a schematic diagram of millimeter-wave radar monitoring according to the present invention;

[0035] Figure 3 This is a schematic diagram showing the positions of three points on an object collected by the present invention;

[0036] Figure 4 This is a schematic diagram of the early warning system of the present invention.

[0037] Figure label:

[0038] 1. Vehicle detection radar, 2. Millimeter-wave radar, 3. Warning lights. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0040] See attached document Figure 1 This embodiment provides a rockfall monitoring and early warning method based on millimeter-wave radar, including the following steps:

[0041] See attached document Figure 2 The millimeter-wave radar 2 is installed in a stable position on the opposite side of the monitored slope. The millimeter-wave radar 2 is adjusted to a horizontal position, and the monitoring area is the slope within its horizontal field of view ∠HFOV and vertical field of view ∠VFOV.

[0042] S1: Millimeter-wave radar 2 high-frequency scanning monitors objects in the area, see attached... Figure 3 The high-frequency scanning results select the position information of the object at three points A, B, and C. The position information includes: horizontal position, height position, and time point. The millimeter-wave radar 2 scans the monitored object at high frequency. When the object moves, the millimeter-wave radar 2 scans and obtains the position information of three points A, B, and C on the object's movement trajectory, which provides support for subsequent calculation of the object's horizontal velocity and initial vertical velocity.

[0043] S2: Calculate the horizontal velocity of the object from point A to point B using the position information. Calculate the horizontal velocity of the object from point B to point C. If horizontal speed equal to horizontal speed If the object is not a falling rock, proceed to step S3; otherwise, determine that the object is not a falling rock and do not issue a warning. Before its next impact, a falling rock will generate horizontal velocity. During the high-frequency acquisition process of the millimeter-wave radar 2, the time difference is very small, and the reduction in horizontal velocity caused by air resistance is negligible. Therefore, when the object's horizontal velocity... With horizontal speed If the horizontal velocities are the same, it indicates that the object's horizontal velocity from point A to point C remains essentially unchanged, consistent with the horizontal motion characteristics of a falling rock. Furthermore, the rock did not touch the ground during its journey from point A to point C, providing a basis for further comparison of the initial vertical velocities. However, if the horizontal velocities are the same, the object could also be vegetation or a bird, thus requiring further judgment in step S3. If the horizontal velocity of the object changes from point A to point C, it indicates that it is not a falling rock, but rather possibly swaying vegetation or a bird flying over the monitoring area, requiring no further judgment.

[0044] S3: Calculate the initial vertical velocity of the object when it travels from point A to point B using its position information. Calculate the initial vertical velocity of the object when it reaches point C from point A. ,if and If the values ​​are equal, the object is identified as a falling rock, and a warning is issued; otherwise, the object is identified as something else, and no warning is issued. Falling rocks only experience vertical falling motion under the influence of gravity. and If the initial vertical velocities are equal and the objects do not touch the ground when moving from point A to point C, then the objects are only subject to gravity in the vertical direction, which is consistent with the vertical motion characteristics of falling rocks, but not consistent with the vertical motion characteristics of vegetation and birds. This is because vegetation and birds are less affected by gravity when moving vertically, and are mainly affected by external forces, so their acceleration is irregular.

[0045] This invention selects the positional information of three points when an object is moving from the collected data. Then, it initially determines whether it is a falling rock based on the horizontal velocity, and confirms that the rock did not reach the ground when the three positional information points were collected. Based on this, it further determines whether it is a falling rock by using the initial vertical velocity. This invention utilizes the characteristic that falling rocks are only affected by gravity during their movement and the small time difference of high-frequency acquisition by millimeter-wave radar 2, which minimizes the influence of external forces on the horizontal velocity of the falling rock, to monitor falling rocks. The overall structure is simple, it can quickly identify and warn of falling rocks, has good monitoring performance, effectively filters interference from birds, vehicles, pedestrians, and vegetation, and is unaffected by weather and optical conditions, providing safety assurance for traffic and production activities.

[0046] As another embodiment of the present invention: refer to the appendix Figure 4 In step S3, after the warning is issued, step S4 is also included. Step S4 includes: turning on the vehicle detection radar 1, and if a vehicle is detected approaching, turning on the warning light 3, such as turning on the high beam.

[0047] In step S1, the millimeter-wave radar 2 measures the position information of the object at points A, B, and C using a time-difference method. Of course, the millimeter-wave radar 2 can also measure the position information of the object at points A, B, and C using other methods.

[0048] As another embodiment of the present invention: In step S2, the horizontal velocity of the object... It is calculated using the following formula:

[0049]

[0050] in, and These represent the horizontal positions of the object at points A and B, respectively. and These are the time points when the object is at point A and point B, respectively.

[0051] As another embodiment of the present invention: In step S2, the horizontal velocity of the object... It is calculated using the following formula:

[0052]

[0053] in, Let C be the horizontal position of the object. This is the time point when the object is at point C.

[0054] As another embodiment of the present invention: in step S3... It is calculated using the following formula:

[0055] =

[0056] in, and These represent the height positions of the object at points A and B, respectively. The acceleration due to gravity (approximately 9.8 m / s²) 2 );

[0057] It is calculated using the following formula:

[0058] =

[0059] in, Let C be the height of the object at point C.

[0060] As another embodiment of the present invention: in step S2, if > ,and and If the difference between the two horizontal velocities is within a predetermined range, the object is judged to be a falling rock, and step S3 is executed; otherwise, the object is judged not to be a falling rock, and no warning is issued. This design takes air resistance into account. Falling rocks are affected by air resistance, causing their horizontal speed to decrease. However, the time difference during high-frequency acquisition by the millimeter-wave radar 2 is very small, limiting the impact of air resistance. Therefore, as long as the difference between the two horizontal velocities is within a certain range, it can be judged that the object is likely a falling rock. This judgment method further improves the monitoring effect.

[0061] In another embodiment of the present invention: in step S1, the location information is obtained through the following steps:

[0062] The millimeter-wave radar 2 measures and calculates the x, y, and z coordinates of the object at time point t, where the z coordinate represents the object's height, and the x and y coordinates represent the object's horizontal position.

[0063] In another embodiment of the present invention: in step S2, the three-dimensional coordinates (X1, Y1, Z1) of the object at time point t1 are obtained by the millimeter-wave radar 2, and the horizontal position of the object at point A is obtained. The coordinates of the object are (X1, Y1); the three-dimensional coordinates of the object at time t2 are (X2, Y2, Z2) obtained by millimeter-wave radar 2, and the horizontal position of the object at point B is... The coordinates are (X2, Y2); the three-dimensional coordinates (X3, Y3, Z3) of the object at time point t3 are obtained by millimeter-wave radar 2, and the horizontal position of the object at point C is... If the coordinates are (X3, Y3), then

[0064] =

[0065] =

[0066] Then calculate and That is, the horizontal velocity of an object and .

[0067] In another embodiment of the present invention: the millimeter-wave radar 2, the vehicle detection radar 1, and the warning light 3 are mounted on a tower, which is positioned opposite or beside the monitoring area. The millimeter-wave radar 2, the vehicle detection radar 1, and the warning light 3 constitute the early warning system of the present invention.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for monitoring and early warning of falling rocks based on millimeter-wave radar, characterized in that, Includes the following steps: S1: The position information of the object in the monitoring area at three points A, B, and C is measured by millimeter-wave radar. The position information includes: horizontal position, height position, and time point. S2: Calculate the horizontal velocity of the object from point A to point B using the location information. Calculate the horizontal velocity of the object from point B to point C. If horizontal speed equal to horizontal speed If the object is not a falling rock, then proceed to step S3; otherwise, determine that the object is not a falling rock and do not issue a warning. S3: Calculate the initial vertical velocity of the object when it reaches point B from point A using the position information. Calculate the initial vertical velocity of the object when it reaches point C from point A. ,if and If the values ​​are equal, the object is identified as a falling rock, and a warning is issued; otherwise, the object is identified as something else, and no warning is issued.

2. The rockfall monitoring and early warning method based on millimeter-wave radar according to claim 1, characterized in that, In step S3, after the warning is issued, step S4 is also included, which includes: turning on the vehicle detection radar, and turning on the warning light if a vehicle is detected approaching.

3. The rockfall monitoring and early warning method based on millimeter-wave radar according to claim 2, characterized in that, In step S1, the millimeter-wave radar measures the position information of the object at three points A, B, and C using an equal time difference method.

4. The rockfall monitoring and early warning method based on millimeter-wave radar according to claim 3, characterized in that, In step S2, the horizontal velocity It is calculated using the following formula: in, and These represent the horizontal positions of the object at points A and B, respectively. and These are the time points when the object is at point A and point B, respectively.

5. The rockfall monitoring and early warning method based on millimeter-wave radar according to claim 4, characterized in that, In step S2, the horizontal velocity It is calculated using the following formula: in, Let C be the horizontal position of the object. The time point is when the object is at point C.

6. The rockfall monitoring and early warning method based on millimeter-wave radar according to claim 5, characterized in that, In step S3, It is calculated using the following formula: = in, and These represent the height positions of the object at points A and B, respectively. The acceleration due to gravity (approximately 9.8 m / s²) 2 ); It is calculated using the following formula: = in, Let C be the height of the object at point C.

7. The rockfall monitoring and early warning method based on millimeter-wave radar according to claim 6, characterized in that, In step S2, if > ,and and If the difference is within the predetermined range, the object is judged to be a falling rock, and step S3 is executed; otherwise, the object is judged not to be a falling rock, and no warning is issued.

8. The rockfall monitoring and early warning method based on millimeter-wave radar according to claim 7, characterized in that, In step S1, the location information is obtained through the following steps: The x, y, and z coordinates of an object at time t are measured and calculated using millimeter-wave radar. The z coordinate represents the object's height, while the x and y coordinates represent the object's horizontal position.

9. The rockfall monitoring and early warning method based on millimeter-wave radar according to claim 8, characterized in that, In step S2, the horizontal position of the object at point A The coordinates are (X1, Y1), and the horizontal position of the object at point B is... The coordinates are (X2, Y2), and the horizontal position of the object at point C is... If the coordinates are (X3, Y3), then = = 。 10. The rockfall monitoring and early warning method based on millimeter-wave radar according to claim 9, characterized in that, The millimeter-wave radar, vehicle detection radar, and warning lights are mounted on the tower.

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