Sensor arrangement method for monitoring displacement of straight tunnel vault based on digital image displacement

Abstract

The present invention provides a method for arranging sensors for monitoring displacement of a straight tunnel vault based on digital image displacement, and relates to the field of engineering monitoring technology. According to actual monitoring requirements, a target is arranged on the vault at a certain distance l, and a single sensor can monitor multiple targets. First, the horizontal distance b and vertical distance c between the sensor and the target are preliminarily set. According to the two forms of single-row and double-row target arrangements, vertical field of view angle verification formulas, horizontal field of view angle verification formulas, and vertical and horizontal occlusion verification formulas are established respectively. The distance a between the sensor and the first target and the number of monitoring sections n are respectively verified to determine whether there is a solution or whether it does not conform to the actual situation. If there is no solution or it does not conform to the actual situation, the values ​​of b and c need to be reset. Finally, by comparing the monitoring lengths nl of the two forms, the parameters of the longer one are selected as the arrangement scheme. The present invention can quickly verify the feasibility of the arrangement and can also simulate multiple arrangement schemes according to actual needs to meet the monitoring requirements of the entire straight tunnel.

Description

Technical Field

[0001] The present invention relates to the technical field of engineering monitoring, and in particular to a method for arranging sensors for monitoring displacement of a straight-segment tunnel vault based on digital image displacement. Background Art

[0002] Vault vertical deformation monitoring is an important component of tunnel structure deformation monitoring. Due to problems in the early stages of tunnel design, construction, and later operations and management, a certain amount of structural deformation can lead to cracking and even collapse of the tunnel or structure. To ensure tunnel structural safety, promptly identify potential hazards during construction and operation, understand tunnel structural deformation, provide timely safety warnings, and prevent dangerous situations, it is necessary to monitor tunnel structural deformation.

[0003] Machine vision-based tunnel structure deformation monitoring technology uses sensors to analyze the three-dimensional spatial relationships between targets to determine the horizontal and vertical displacements between each target point, enabling two-dimensional monitoring of the tunnel structure. This technology offers advantages such as long monitoring range, high accuracy, and automation. In recent years, this monitoring method has begun to be applied to bridge deflection and building deformation monitoring, achieving relatively good results. However, its application in tunnel structure deformation is relatively limited, as a comprehensive sensor placement method is still lacking. Therefore, improving sensor placement methods will have a positive impact on promoting the application of this technology and controlling monitoring costs. Summary of the Invention

[0004] Purpose of the invention: The present invention proposes a method for arranging sensors for monitoring displacement of straight-line tunnel vaults based on digital image displacement, aiming to effectively solve the above-mentioned problems existing in the prior art.

[0005] As a first aspect of the present invention, a method for arranging sensors for monitoring displacement of a straight tunnel vault based on digital image displacement is proposed, comprising the following steps:

[0006] Step 1: Preliminarily determine the horizontal distance b and vertical distance c between the sensor and the target based on the tunnel cross-sectional dimensions;

[0007] Step 2: Substitute the horizontal distance b and vertical distance c into the single-row target verification formula to find the range of integers n that can solve the distance a between the sensor and the first target. Select an appropriate value of a based on the range of a.

[0008] Step 3. Substitute the horizontal distance b and vertical distance c into the double-row target verification formula to find the range of integers n that can solve the distance a between the sensor and the first target. Select an appropriate value of a based on the range of a.

[0009] Step 4. If there is no solution in steps 2 and 3, adjust the values ​​of horizontal distance b and vertical distance c, repeat steps 2 and 3, and obtain the corresponding value of n;

[0010] Step 5: Select the most appropriate n value obtained in step 4. nl is the monitoring distance of a single sensor, so the sensor spacing is (n-1)l;

[0011] Step 6: Arrange displacement monitoring sensors on the straight tunnel vault according to the sensor spacing (n-1)l.

[0012] In a further embodiment of the first aspect, the values ​​of the horizontal distance b and the vertical distance c between the sensor and the target to be preliminarily set in step 1 should be based on a reasonable assumption that the sensor is arranged on the inner wall of the tunnel or on the horizontal ground.

[0013] In a further embodiment of the first aspect, step 2 includes a single-row target verification formula derivation process:

[0014] (1) Verification of the horizontal field of view angle is used to verify whether the measured targets are all within the horizontal field of view angle range of the sensor. The specific situation is:

[0015]

[0016] in, is the lateral field of view of the sensor; n is the number of monitoring segments; l is the distance between monitoring points; a is the distance from the sensor to the first target.

[0017] (2) Verification of vertical field of view angle: used to verify whether the measured targets are all within the vertical field of view angle range of the sensor. The specific situation is:

[0018]

[0019] in, is the vertical field of view of the sensor.

[0020] (3) Horizontal occlusion verification is used to verify whether the second monitoring target will block the signal of the last target in the horizontal direction. The specific situation is:

[0021]

[0022] Where t is the size of the target, and the subscripts x, y, and z are the width, height, and length of the target, respectively.

[0023] (4) Vertical occlusion verification is used to verify whether the second monitoring target will block the signal of the last target in the vertical direction. The specific situation is:

[0024]

[0025] (5) In summary, the formula for the value range of a is derived, in which the field of view angle verification must meet the requirements, while the line of sight occlusion verification only needs to meet one of the horizontal or vertical requirements. The specific situation is:

[0026]

[0027] (6) Find the range of integer n that makes a solvable. Select the appropriate n based on the long-distance monitoring performance of the sensor, which must satisfy a+nl max , and select the appropriate value of a according to the value range of a. max It is the maximum monitoring distance within a certain error of the sensor.

[0028] In a further embodiment of the first aspect, step 3 includes a double-row target verification formula derivation process:

[0029] (1) Verification of the horizontal field of view angle is used to verify whether the measured targets are all within the horizontal field of view angle range of the sensor. The specific situation is:

[0030]

[0031] Where d is the offset between the target and the longitudinal centerline of the tunnel + 0.5t x .

[0032] (2) Verification of vertical field of view angle: used to verify whether the measured targets are all within the vertical field of view angle range of the sensor. The specific situation is:

[0033]

[0034] in, is the vertical field of view of the sensor.

[0035] (3) Different-row occlusion verification is used to verify whether there will be occlusion between targets that are not in the same row. The specific situation is:

[0036] Establish a spatial coordinate system, where the x-axis is the direction from the tunnel center to the arch edge, the y-axis is the direction of the tunnel extension, and the z-axis is the direction from the tunnel center to the arch top. Let the sensor location coordinates be , the center of the first target is located at , the coordinates of the center point of the nth target are , the coordinates of the center point of the n+1th target are , so the equation of the straight line connecting the nth target and the sensor is:

[0037]

[0038] When y=nl, that is, in the n+1th target plane, the straight line intersects at point​ :

[0039]

[0040] and The absolute value of the x-coordinate difference needs to be greater than , the absolute value of the z coordinate difference needs to be greater than ;

[0041] in, is the magnified width of the previous target projected onto the next target surface along the sensor’s line of sight. ;

[0042] in, is the magnified height of the previous target projected onto the next target surface along the sensor’s line of sight. ;

[0043] Therefore, the calculation formula for different row occlusion is obtained:

[0044]

[0045] Where t is the size of the target, and the subscripts x, y, and z are the width, height, and length of the target, respectively; is the lateral field of view angle of the sensor; is the vertical field of view of the sensor; n is the number of monitoring segments; l is the distance between monitoring points; a is the distance from the sensor to the first target.

[0046] (4) Verification of horizontal occlusion in the same row: to verify whether there is horizontal occlusion between targets in the same row. The specific situation is:

[0047]

[0048] (5) Same-row vertical occlusion verification is used to verify whether there is vertical occlusion between targets in the same row. The specific situation is:

[0049]

[0050] (6) Combining the four verification formulas, the formula for the value range of a is derived. The field of view verification must meet the requirements, while the line of sight occlusion verification only needs to meet one of them. The specific situation is:

[0051]

[0052] (7) Find the range of integer n that makes a solvable. Select the appropriate n based on the long-distance monitoring performance of the sensor, which must satisfy , and select the appropriate value of a according to the value range of a.

[0053] In a further embodiment of the first aspect, in step 4, if the lateral field of view angle verification or the lateral occlusion verification fails or the calculated a value is large, the b value can be increased and the single-row target verification and double-row target verification can be performed again. The vertical verification is the same, but the adjusted value is not allowed to exceed the tunnel size.

[0054] In a further embodiment of the first aspect, in step 5, longer tunnels often require multiple sensors to monitor targets on multiple straight segments. For the continuity of monitoring, it is necessary to ensure that the two front and rear sensors have at least one common monitoring target to facilitate the front and rear connection of the tunnel vault data. Therefore, the distance between the sensors is (n-1)l.

[0055] As a second aspect of the present invention, a computer-readable storage medium is proposed, which stores at least one executable instruction. When the executable instruction is run on an electronic device, the electronic device executes the method for arranging sensors for monitoring the displacement of a straight-line tunnel vault based on digital image displacement as disclosed in the first aspect and its further embodiments.

[0056] Beneficial effects: The method adopted by the present invention can quickly and accurately determine the layout parameters and number of sensors in the tunnel, effectively reducing the trial and error costs in the field; the reasonable layout plan of the sensors ensures that the minimum number of sensors can monitor the entire tunnel, reducing the monitoring cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 This is a schematic diagram of the transverse verification of sensors when a single row of targets is arranged according to an embodiment of the present invention.

[0058] Figure 2 This is a schematic diagram of the vertical verification of sensors when single-row or double-row targets are arranged according to an embodiment of the present invention.

[0059] Figure 3 This is a schematic diagram of the transverse verification of sensors when double-row targets are arranged according to an embodiment of the present invention.

[0060] Figure 4 It is a schematic diagram of the arrangement of tunnel cross-section sensors provided by an embodiment of the present invention.

[0061] Figure 5 This is a schematic diagram of the distribution of tunnel sensor layout points provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0062] In the following description, numerous specific details are provided to provide a more thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without one or more of these details. In other instances, certain technical features well known in the art have not been described to avoid confusion with the present invention.

[0063] Example 1:

[0064] For a 4km straight section highway tunnel with an inner diameter of R=6m, the required tunnel crown settlement monitoring points are arranged every 10m, i.e. l=10m. The target size installed on the crown is 0.12m×0.12m×0.25m, i.e. , , , sensor lateral field of view , vertical field of view The maximum monitoring distance for the sensor to ensure that the monitoring results are within 1mm error is 400m. The following uses this technology to determine the layout parameters of the sensor.

[0065] Step 1: Preliminarily determine the horizontal distance b and vertical distance c between the sensor and the target based on the tunnel cross-sectional dimensions;

[0066] Assuming the length of the sensor mounting bracket is 0.5m,

[0067] Pick ,but

[0068] Step 2: Substitute b and c into the single-row target verification formula to find the range of integer n that makes a solvable, and select the appropriate value of a based on the range of a values;

[0069] The targets that the sensor can monitor must meet two conditions. First, all targets must be within the sensor's field of view. Second, there must be no line of sight obstructions during monitoring. The derivation process of the verification formula is given below:

[0070] (1) Verify the horizontal field of view angle. The layout diagram is as follows: Figure 1 , used to verify whether the measured targets are all within the sensor's lateral field of view. The specific situation is:

[0071]

[0072] in, is the lateral field of view of the sensor; n is the number of monitoring segments; l is the distance between monitoring points; a is the distance from the sensor to the first target.

[0073] (2) Verify the vertical field of view angle. The layout diagram is as follows: Figure 2 , used to verify whether the measured targets are all within the vertical field of view of the sensor. The specific situation is:

[0074]

[0075] in, is the vertical field of view of the sensor.

[0076] (3) Verification of lateral obstruction, the layout diagram is as follows Figure 1 , used to verify whether the second monitoring target will block the signal of the last target in the horizontal direction. The specific situation is:

[0077]

[0078] Where t is the size of the target, and the subscripts x, y, and z are the width, height, and length of the target, respectively.

[0079] (4) Verification of vertical occlusion, layout diagram as shown Figure 2 , used to verify whether the second monitoring target will block the signal of the last target in the vertical direction. The specific situation is:

[0080]

[0081] (5) In summary, the formula for the value range of a is derived, in which the field of view angle verification must meet the requirements, while the line of sight occlusion verification only needs to meet one of the horizontal or vertical requirements. The specific situation is:

[0082] (1)

[0083] (6) Find the range of integer n that makes a solvable. Select the appropriate n based on the long-distance monitoring performance of the sensor, which must satisfy a+nl max , and select the appropriate value of a according to the value range of a.

[0084] Assuming n=25, substitute all parameters into (1) to obtain the value range of a:

[0085]

[0086] Take a=120m, , which is consistent with the accuracy verification.

[0087] Step 3: Substitute b and c into the double-row target verification formula, find the range of integer n that makes a solvable, and select the appropriate value of a based on the value range of a.

[0088] (1) Verify the horizontal field of view angle. The layout diagram is as follows: Figure 3 , used to verify whether the measured targets are all within the sensor's lateral field of view. The specific situation is:

[0089]

[0090] Where d is the offset between the target and the longitudinal centerline of the tunnel + 0.5t x .

[0091] (2) Verify the vertical field of view angle. The layout diagram is as follows: Figure 2 ​, used to verify whether the measured targets are all within the vertical field of view of the sensor. The specific situation is:

[0092]

[0093] in, is the vertical field of view of the sensor.

[0094] (3) Different-row occlusion verification is used to verify whether there will be occlusion between targets that are not in the same row. The specific situation is:

[0095] Establish a spatial coordinate system, where the x-axis is the direction from the tunnel center to the arch edge, the y-axis is the direction of the tunnel extension, and the z-axis is the direction from the tunnel center to the arch top. Let the sensor location coordinates be , the center of the first target is located at , the coordinates of the center point of the nth target are , the coordinates of the center point of the n+1th target are , so the equation of the straight line connecting the nth target and the sensor is:

[0096]

[0097] When y=nl, that is, in the n+1th target plane, the straight line intersects at point :

[0098]

[0099] and The absolute value of the x-coordinate difference needs to be greater than , the absolute value of the z coordinate difference needs to be greater than .

[0100] in, It is the magnified width of the previous target projected onto the next target surface along the sensor's line of sight:

[0101]

[0102] in, It is the magnified height of the previous target projected onto the next target surface along the sensor's line of sight:

[0103]

[0104] Therefore, the calculation formula for different row occlusion is obtained:

[0105]

[0106] (4) Verification of horizontal occlusion in the same row: to verify whether there will be horizontal occlusion between targets in the same row. The layout diagram is as follows: Figure 1 , where the distance between targets becomes 2l, specifically:

[0107]

[0108] (5) Verification of vertical occlusion in the same row: to verify whether there will be vertical occlusion between targets in the same row. The layout diagram is as follows: Figure 2 , where the distance between targets becomes 2l, specifically:

[0109]

[0110] (6) Combining the four verification formulas, the formula for the value range of a is derived. The field of view verification must meet the requirements, while the line of sight occlusion verification only needs to meet one of them. The specific situation is:

[0111]

[0112] (7) Find the range of integer n that makes a solvable. Select the appropriate n based on the long-distance monitoring performance of the sensor, which must satisfy a+nl max , and select the appropriate value of a according to the value range of a.

[0113] Assuming n=25, substitute all parameters into (1) to obtain the value range of a:

[0114]

[0115] Take a=130m, , which is consistent with the accuracy verification

[0116] Step 4: If there is no solution in steps 2 and 3, adjust the values ​​of b and c, repeat steps 2 and 3, and obtain the corresponding value of n;

[0117] Since steps 2 and 3 have solutions, there is no need to adjust the values ​​of b and c.

[0118] Step 5: Select the most appropriate value of n obtained in step 4. nl is the monitoring distance of a single sensor, so the sensor spacing is (n-1)l.

[0119] Because the results of single-row arrangement are better than those of double-row arrangement, single-row arrangement is adopted.

[0120] Monitoring segments , , a single sensor monitors distance m, sensor spacing m.

[0121] Total number of sensors =​ Take 17, the first sensor in the tunnel starts from m starts to be arranged, and the cross-sectional sensor arrangement diagram is as follows Figure 4 The tunnel sensor layout diagram is shown in Figure 5 shown.

[0122] The method adopted by the present invention can quickly and accurately determine the layout parameters and number of sensors in the tunnel, effectively reducing the trial and error cost in the field space; the reasonable layout plan of the sensors ensures that the minimum number of sensors can monitor the entire tunnel, reducing the monitoring cost.

[0123] As described above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the present invention itself. Various changes may be made to it in form and detail without departing from the spirit and scope of the present invention as defined in the appended claims.

Claims

1. A method for arranging sensors for monitoring displacement of straight tunnel vaults based on digital image displacement, characterized in that: The steps include: Step 1: Preliminarily determine the horizontal distance b and vertical distance c between the sensor and the target based on the tunnel cross-sectional dimensions; Step 2: Substitute the horizontal distance b and vertical distance c into the single-row target verification formula to find the range of integers n that allow the distance a between the sensor and the first target to be solved. Based on the range of a, select an appropriate value of a, specifically: Field of view angle verification: Verify whether the measured targets are within the sensor's horizontal field of view angle range and vertical field of view angle range respectively. The expressions are as follows: Where, is the lateral field of view angle of the sensor; is the vertical field of view of the sensor; n is the number of monitoring segments; l is the distance between monitoring points; a is the distance between the sensor and the first target; Line of sight obstruction verification: Verify whether the second-to-last monitoring target will block the signal of the last target in the horizontal and vertical directions. The expression is as follows: Where t is the size of the target, and the subscripts x, y, and z are the width, height, and length of the target, respectively; Calculate the range of the distance a between the sensor and the first target, and select an appropriate value of a based on the range of a; Step 3: Substitute the horizontal distance b and vertical distance c into the double-row target verification formula to find the range of integers n that allow the distance a between the sensor and the first target to be solved. Based on the range of a, select an appropriate value of a, specifically: Step 3-1, Horizontal Field of View Angle Verification: Verify whether the measured targets are within the sensor's horizontal field of view angle range: Where d is the offset between the target and the longitudinal centerline of the tunnel + 0.5t x ; Step 3-2: Verify vertical field of view: Verify whether all measured targets are within the vertical field of view of the sensor: Where, is the vertical field of view of the sensor; Step 3-3, different row occlusion check: check whether there is occlusion between targets that are not in the same row; Step 3-4: Verify whether there is lateral obstruction between targets in the same row: Step 3-5: Verify vertical occlusion between targets in the same row: Verify whether there is vertical occlusion between targets in the same row: Step 3-6: Combine the calculation results from steps 3-1 to 3-4 to calculate the range of the distance a between the sensor and the first target; Step 4. If there is no solution in steps 2 and 3, adjust the values ​​of horizontal distance b and vertical distance c, repeat steps 2 and 3, and obtain the corresponding value of n; Step 5: Select the appropriate n value obtained in step 2, step 3, or step 4. nl is the monitoring distance of a single sensor, so the sensor spacing is (n-1)l; Step 6: Arrange displacement monitoring sensors on the straight tunnel vault according to the sensor spacing (n-1)l.

2. The method for arranging sensors for monitoring displacement of straight tunnel vaults based on digital image displacement according to claim 1 is characterized in that: The calculated distance a from the sensor to the first target satisfies the following conditions: The value range of the distance a between the sensor and the first target satisfies both the horizontal field of view angle range and the vertical field of view angle range, and the value range of the distance a between the sensor and the first target satisfies the horizontal or vertical conditions in the line of sight occlusion verification. The expression is as follows: Where t is the size of the target, and the subscripts x, y, and z are the width, height, and length of the target, respectively; is the lateral field of view angle of the sensor; is the vertical field of view of the sensor; n is the number of monitoring segments; l is the distance between monitoring points; a is the distance from the sensor to the first target.

3. The method for arranging sensors for monitoring displacement of straight tunnel vaults based on digital image displacement according to claim 2 is characterized in that: The method of selecting a suitable value of a according to the value range of a includes: Find the range of integers n that can solve the distance a between the sensor and the first target. Select the appropriate n based on the long-distance monitoring performance of the sensor, and it must satisfy a+nl max , and select the appropriate value of a according to the value range of a;​ Among them, S max The maximum monitoring distance within the predetermined error of the sensor.

4. The method for arranging sensors for monitoring displacement of straight tunnel vaults based on digital image displacement according to claim 1 is characterized in that: Step 3 also includes: Step 3-6: Combine the verification results of steps 3-1 to 3-4 to calculate the value range of the distance a between the sensor and the first target. The value range of the distance a between the sensor and the first target satisfies both the horizontal field of view angle range and the vertical field of view angle range. The value range of the distance a between the sensor and the first target satisfies the different-row occlusion verification or the same-row horizontal occlusion verification or the same-row horizontal occlusion verification. The expression is as follows: Step 3-7, find the range of integer n that makes a solvable. Select the appropriate n based on the long-distance monitoring performance of the sensor, which must satisfy a+nl max , and select the appropriate value of a according to the value range of a;​ Among them, S max The maximum monitoring distance within the predetermined error of the sensor.

5. The method for arranging sensors for monitoring displacement of straight tunnel vaults based on digital image displacement according to claim 4 is characterized in that: Step 3-3 further includes: Establish a spatial coordinate system, where the x-axis is the direction from the tunnel center to the arch edge, the y-axis is the direction of tunnel extension, and the z-axis is the direction from the tunnel center to the arch top; Let the sensor location coordinates be , the center of the first target is located at , the coordinates of the center point of the nth target are , the coordinates of the center point of the n+1th target are , so the equation of the straight line connecting the nth target and the sensor is: When y=nl, that is, in the n+1th target plane, the straight line intersects at point : and The absolute value of the x-coordinate difference needs to be greater than , the absolute value of the z coordinate difference needs to be greater than ; in, is the magnified width of the previous target projected onto the next target surface along the sensor’s line of sight. ; in, is the magnified height of the previous target projected onto the next target surface along the sensor’s line of sight. ; Therefore, the calculation formula for different row occlusion is obtained: Where t is the size of the target, and the subscripts x, y, and z are the width, height, and length of the target, respectively; is the lateral field of view angle of the sensor; is the vertical field of view of the sensor; n is the number of monitoring segments; l is the distance between monitoring points; a is the distance from the sensor to the first target.

6. The method for arranging sensors for monitoring displacement of straight tunnel vaults based on digital image displacement according to claim 1 is characterized in that: In step 4, if the lateral field of view angle verification or the lateral occlusion verification fails or the calculated a value is greater than the preset value, the b value is increased and the single-row target verification and double-row target verification are performed again. The vertical verification is similar, but the adjusted value is not allowed to exceed the tunnel size. In step 6, tunnels with a length exceeding a predetermined value require multiple sensors to monitor targets on multiple straight segments. For the sake of monitoring continuity, it is necessary to ensure that the two front and rear sensors have at least one common monitoring target to facilitate the front and rear connection of the tunnel vault data. Therefore, the distance between sensors is (n-1)l.

7. A computer-readable storage medium, characterized in that The storage medium stores at least one executable instruction. When the executable instruction is executed on the electronic device, the electronic device executes the method for arranging sensors for monitoring displacement of straight-segment tunnel vaults based on digital image displacement according to any one of claims 1 to 6.

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