An underwater inspection robot wireless autonomous positioning device for foundation pit construction and a positioning method thereof

Abstract

To address the difficulty of positioning inspection instruments during underwater excavation quality inspection of foundation pits, this invention provides a wireless autonomous positioning device for an underwater inspection robot in foundation pit construction. The device includes a set of reference point power supply arrays and an inspection instrument. For small foundation pits, the inspection instrument calculates the distance between itself and each reference point power supply by detecting the electric field frequency and intensity emitted by different reference point power supplies, thereby calculating its coordinate position. For large foundation pits, where the signal strength of the reference point power supplies at the pit edge is insufficient, a set of surface buoys is added. The reference point array is equipped with a laser rangefinder, which can perform more than three distance measurements on each buoy to locate it. Subsequently, through the surface buoy array, the power supplies are activated one by one to form an electric field in the muddy water layer within the pit. Each power supply uses a different frequency range, and the underwater inspection instrument, equipped with an electric field strength detector, calculates the distance between the buoys by detecting the electric field frequency and intensity.

Description

Technical Field

[0001] This invention belongs to the field of underwater excavation technology for foundation pits, and specifically relates to a wireless autonomous positioning device and positioning method for an underwater inspection robot for foundation pit construction. Background Technology

[0002] The development of ultra-deep underground spaces in soft soil and water-rich areas faces safety risks caused by confined water. Conventional dry excavation methods are prone to adverse situations such as seepage in the retaining walls and sudden water inrush at the bottom of the pit. In recent years, a foundation pit construction method using underwater excavation has been gradually developed. This method first constructs the retaining walls, then effectively reduces or even balances the water and soil pressure difference between the inside and outside of the pit by filling the pit with water. Underwater soil is then extracted using specialized equipment such as grab buckets or cutter suction hoppers, thus effectively protecting the foundation pit from the impact of sudden water inrush during the excavation stage. Subsequently, the bottom is sealed by underwater concrete pouring, and finally the water in the pit is pumped out for structural construction.

[0003] Underwater concrete pouring is a concealed construction process, making quality control relatively difficult. If problems arise during the bottom sealing concrete construction, the bottom slab is prone to leakage, sudden surges, or even cracking under the influence of groundwater after the water in the pit is drained. Therefore, before draining the pit after underwater concrete pouring, a comprehensive inspection of the bottom sealing concrete for leakage must be conducted. If leakage points are found, key information such as the location and scale of the leakage needs to be determined to provide a reference for subsequent remediation and treatment measures.

[0004] When inspecting for leakage in the bottom slab of an underwater excavation pit, most of the work is done manually, with divers diving in to check point by point. This is risky and difficult. Some projects use underwater robots, but these are usually equipped with umbilical cables to transmit location data. For underwater excavation pits, there is a relatively complex multi-layered and multi-channel support structure system, which is extremely inconvenient for underwater operations with cables. Summary of the Invention

[0005] In order to accurately and effectively detect leakage in the excavated bottom slab, this invention provides a wireless autonomous positioning device and positioning method for an underwater inspection robot in foundation pit construction.

[0006] The technical solution of the wireless autonomous positioning device for an underwater inspection robot in foundation pit construction according to the present invention is as follows: A wireless autonomous positioning device for an underwater inspection robot in foundation pit construction, characterized in that it includes: A foundation pit is excavated on the ground. A retaining wall is set around the foundation pit. A mud-water layer and a mud slurry layer are distributed from top to bottom in the foundation pit. The mud slurry layer is located on the upper side of the bottom of the foundation pit. A reference point power supply array, comprising three or more reference point power supplies respectively set at positions around the perimeter of the underwater excavation pit above the water surface, to construct a reference coordinate system, and capable of transmitting point power supply electric field signals of different electric field frequencies into the pit one by one, with a laser rangefinder configured on one side of the reference point power supply to form a laser rangefinder array. A buoy array distributed on the water surface, the buoy array comprising buoys capable of constructing a planar rectangular coordinate system and arranged on the surface of the muddy water layer, wherein the laser rangefinder can measure the distance of each buoy in the water surface buoy array, thereby locating each buoy; A survey instrument, which calculates the distance between power sources in a power source array relative to different reference points by detecting the electric field frequency and electric field strength; the survey instrument also calculates the distance between different buoys by detecting the electric field frequency and electric field strength.

[0007] Furthermore, the buoy includes a shell capable of floating on the surface of the muddy water layer. Inside the shell, there is an electric field strength detector, a buoy controller, and a power module. On the outside of the shell, there is an electric propeller multi-directional thruster and a buoy point power supply capable of moving the buoy to the required position. The buoy controller is communicatively connected to the electric field strength detector and the electric propeller multi-directional thruster, respectively. The power module is electrically connected to the electric field strength detector, the buoy controller, the buoy point power supply, and the electric propeller multi-directional thruster, respectively.

[0008] Furthermore, the inspection device includes a head cover, a central rod, and a base with an overall cross-shaped structure, with the central rod positioned between the head cover and the base.

[0009] Furthermore, the helmet is equipped with a top electric field strength detector, a hydraulic detector, a buoyancy control module, a ballast water tank, a thruster, a control processing host, a power supply module, and an electric field signal control module. The ballast water tank is located at the upper end of the helmet, the hydraulic detector and the buoyancy control module are located inside the ballast water tank, the top electric field strength detector is located at the top of the ballast water tank, and the thrusters are symmetrically located on both sides of the helmet. The control processing host, power supply module, and electric field signal control module are all located inside the helmet. The control processing host is communicatively connected to the top electric field strength detector, hydraulic detector, buoyancy control module, ballast water tank, thruster, and electric field signal control module, respectively. The power supply module is electrically connected to the top electric field strength detector, hydraulic detector, buoyancy control module, thruster, control processing host, and electric field signal control module, respectively.

[0010] This invention also discloses a positioning method for a wireless autonomous positioning device for an underwater inspection robot in foundation pit construction. Specifically targeting foundation pits with limited area, this positioning method is based on the wireless autonomous positioning device for an underwater inspection robot in foundation pit construction as described in any one of claims 1-4, and is characterized by comprising: First step: Set up three reference power sources. The electrical signals emitted by the three power sources O, A, and B have frequencies of freq1, freq2, and freq3, respectively. Assume that they are directly arranged to form a rectangular coordinate system with the origin at O ​​and three orthogonal coordinate axes OX, OY, and OZ, where point O is at coordinates (0, 0, 0), point A is at coordinates (a, 0, 0), and point B is at coordinates (0, b, 0). The second step: The underwater inspection device is equipped with an electric field frequency detector and an electric field strength detector. The frequency of the electric signal, freq1, freq2, and freq3, is measured by the electric field frequency detector to identify which point power source, O, A, or B, the signal originates from. The electric field strength detector can measure the electric field strength E(r) at this point. For a point power source in a uniform medium, its electric field strength distribution is directly proportional to the resistivity ρ and the current I, and inversely proportional to the square of the distance, d^2. Where ρ is the resistivity of the liquid, I is the total current flowing from the point source, r is the distance to the point source, and E(d) is the magnitude of the electric field intensity; the formula can be used to calculate: Based on the above method for calculating distance r and the method for distributing the electric field source, the distances from the underwater inspection instrument P to points O, A, and B are d_op, d_ap, and d_bp, respectively. Then, based on geometric knowledge, the coordinates of point P in a given coordinate system can be calculated as follows: Thus, the method for locating the inspection instrument in the relatively homogeneous upper mud and water layer (approximately tens of meters high) can be determined.

[0011] This invention also discloses a positioning method for a wireless autonomous positioning device for an underwater inspection robot in foundation pit construction, specifically for large-area foundation pits, characterized by including... First step: Set up three reference power sources. The electrical signals emitted by the three power sources O, A, and B have frequencies of freq1, freq2, and freq3, respectively. Assume that they are directly arranged to form a rectangular coordinate system with the origin at O ​​and three orthogonal coordinate axes OX, OY, and OZ, where point O is at coordinates (0, 0, 0), point A is at coordinates (a, 0, 0), and point B is at coordinates (0, b, 0). Buoys P1, P2, and P3 are scattered on the water surface at a certain distance. The angle difference of the triangle formed by the three buoys should not be too large. Set up laser rangefinders at the positions of the three power sources O, A, and B to obtain the absolute distance D = dop,i,dap,i,dbp,i (i=1,2,3). Second step: The first layer (reference coordinate system) is the OAB plane, which serves as the XY plane (i.e., z=0). The formula for the coordinates of the buoy point in the reference coordinate system is the same as in Case 1 above. ) Third step: with Construct a local coordinate system (with With the origin, (x-axis) Fourth step: The inspection instrument T determines the relationship with the electric field strength using the above-mentioned electric field strength measurement method. Distance between the three buoy points ( ), in the Constructing coordinates in a local coordinate system ,in: in: in: Step 5: Using the coordinate transformation formula, the coordinates of the inspection instrument T in the reference coordinate system are: : Sixth step: At the same time, the inspection instrument is also equipped with a power transmitter to build an electric field in the water environment of the foundation pit. The water surface buoy is also equipped with an electric field strength detector and an electric propeller multi-directional thruster. Once the electric field strength is too weak, it will autonomously cruise in four directions to find a position where the electric field strength meets the detection strength of the equipment. Step 7: At the same time, the water surface buoy array is also based on the reference point, and the coordinate position of each buoy is calculated in real time using a laser rangefinder to keep the angle difference of the triangle formed by the buoy array as little as possible to less than 30°. Step 8: At this point, a buoy array is used to enhance the local electric field, thereby automatically adapting to the position of the underwater inspection instrument and accurately capturing the coordinate position of the inspection instrument in real time.

[0012] This invention discloses a wireless autonomous positioning device and method for an underwater inspection robot in foundation pit construction. The device features a reasonable overall design, simple structure, and convenient operation. Multiple reference point arrays are set around the perimeter of the foundation pit. A laser rangefinder is configured to perform at least three distance measurements on each buoy in the surface buoy array, thus locating the buoy. Subsequently, through the surface buoy array, power supplies are activated one by one to form an electric field in the muddy water layer within the pit. Each power supply uses a different frequency range. The underwater inspection robot, equipped with an electric field strength detector, calculates the distances between different buoys based on the detected electric field frequency and intensity. Finally, based on the measured distances, a coordinate conversion formula for the underwater inspection robot is provided, offering an effective solution to the positioning challenges of underwater inspection. Attached Figure Description

[0013] Figure 1 This is a coordinate diagram of a wireless autonomous positioning device and positioning method for an underwater inspection robot in foundation pit construction according to the present invention.

[0014] Figure 2 This is a schematic diagram of the inspection instrument structure of a wireless autonomous positioning device and positioning method for an underwater inspection robot in foundation pit construction according to the present invention. Detailed Implementation

[0015] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer from the following description and claims. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.

[0016] Example 1 refer to Figures 1 to 2 This embodiment of a wireless autonomous positioning device for an underwater inspection robot in foundation pit construction includes a foundation pit, a reference point power array, a buoy array, and an inspection instrument.

[0017] The foundation pit is excavated on the stratum and surrounded by retaining walls. Inside the foundation pit, from top to bottom, there are layers of mud and water and layers of mud slurry, with the mud slurry layer located on the upper side of the bottom of the foundation pit.

[0018] The reference point power supply array includes three or more reference point power supplies respectively set at positions around the underwater excavation pit above the water surface to construct a reference coordinate system. It can transmit point power supply electric field signals of different electric field frequencies into the pit one by one. A laser rangefinder is configured on one side of the reference point power supply to form a laser rangefinder array.

[0019] Buoy arrays are used to distribute on the water surface. A buoy array consists of buoys that can construct a planar rectangular coordinate system and are arranged on the surface of the muddy water layer. A laser rangefinder can measure the distance of each buoy in the buoy array, thereby locating each buoy.

[0020] The inspection instrument 100 calculates the distance between power sources in the power source array relative to different reference points by detecting the electric field frequency and electric field strength, and calculates the distance between different buoys by detecting the electric field frequency and electric field strength.

[0021] The buoy includes a shell capable of floating on the surface of the muddy water layer. Inside the shell are an electric field strength detector, a buoy controller, and a power module. On the outside of the shell are an electric propeller multi-directional thruster and a buoy point power supply that can move the buoy to the required position. The buoy controller is communicatively connected to the electric field strength detector and the electric propeller multi-directional thruster. The power module is electrically connected to the electric field strength detector, the buoy controller, the buoy point power supply, and the electric propeller multi-directional thruster.

[0022] The inspection device 100 includes a head cover 110, a central rod 120, and a base 130 with an overall cross-shaped structure. The central rod 120 is located between the head cover 110 and the base 130.

[0023] The helmet 110 is equipped with a top electric field strength detector 111, a hydraulic detector 112, a buoyancy control module 113, a ballast water tank 114, a thruster 116, a control processing host 115, a power supply module 118, and an electric field signal control module 119. The ballast water tank 114 is located at the upper end of the helmet 110. The hydraulic detector 112 and the buoyancy control module 113 are located inside the ballast water tank 114. The top electric field strength detector 111 is located at the top of the ballast water tank 114. The thrusters 116 are symmetrically arranged on both sides of the helmet 110.

[0024] The control processing host 115, the power supply module 118, and the electric field signal control module 119 are all located inside the head cover 110. The control processing host 115 is communicatively connected to the top electric field strength detector 111, the hydraulic detector 112, the buoyancy control module 113, the ballast water tank 114, the thruster 116, and the electric field signal control module 119, respectively. The power supply module 118 is electrically connected to the top electric field strength detector 111, the hydraulic detector 112, the buoyancy control module 113, the thruster 116, the control processing host 115, and the electric field signal control module 119, respectively.

[0025] Example 2 A positioning method for a wireless autonomous positioning device for an underwater inspection robot in foundation pit construction, specifically for foundation pits with limited area, is based on the wireless autonomous positioning device for an underwater inspection robot in foundation pit construction as described in any one of claims 1-4, and is characterized by comprising: First step: Set up three reference power sources. The electrical signals emitted by the three power sources O, A, and B have frequencies of freq1, freq2, and freq3, respectively. Assume that they are directly arranged to form a rectangular coordinate system with the origin at O ​​and three orthogonal coordinate axes OX, OY, and OZ, where point O is at coordinates (0, 0, 0), point A is at coordinates (a, 0, 0), and point B is at coordinates (0, b, 0). The second step: The underwater inspection device is equipped with an electric field frequency detector and an electric field strength detector. The frequency of the electric signal, freq1, freq2, and freq3, is measured by the electric field frequency detector to identify which point power source, O, A, or B, the signal originates from. The electric field strength detector can measure the electric field strength E(r) at this point. For a point power source in a uniform medium, its electric field strength distribution is directly proportional to the resistivity ρ and the current I, and inversely proportional to the square of the distance, d^2. Where ρ is the resistivity of the liquid, I is the total current flowing from the point source, r is the distance to the point source, and E(d) is the magnitude of the electric field intensity; the formula can be used to calculate: Based on the above method for calculating distance r and the method for distributing the electric field source, the distances from the underwater inspection instrument P to points O, A, and B are d_op, d_ap, and d_bp, respectively. Then, based on geometric knowledge, the coordinates of point P in a given coordinate system can be calculated as follows: Thus, the method for locating the inspection instrument in the relatively homogeneous upper mud and water layer (approximately tens of meters high) can be determined.

[0026] Example 3 This invention also discloses a positioning method for a wireless autonomous positioning device of an underwater inspection robot for foundation pit construction, specifically for large-area foundation pits, including... First step: Set up three reference power sources. The electrical signals emitted by the three power sources O, A, and B have frequencies of freq1, freq2, and freq3, respectively. Assume that they are directly arranged to form a rectangular coordinate system with the origin at O ​​and three orthogonal coordinate axes OX, OY, and OZ, where point O is at coordinates (0, 0, 0), point A is at coordinates (a, 0, 0), and point B is at coordinates (0, b, 0). Buoys P1, P2, and P3 are scattered on the water surface at a certain distance. The angle difference of the triangle formed by the three buoys should not be too large. Set up laser rangefinders at the positions of the three power sources O, A, and B to obtain the absolute distance D = dop,i,dap,i,dbp,i (i=1,2,3). Second step: The first layer (reference coordinate system) is the OAB plane, which serves as the XY plane (i.e., z=0). The formula for the coordinates of the buoy point in the reference coordinate system is the same as in Case 1 above. ) Third step: with Construct a local coordinate system (with With the origin, (x-axis) Fourth step: The inspection instrument T determines the relationship with the electric field strength using the above-mentioned electric field strength measurement method. Distance between the three buoy points ( ), in the Constructing coordinates in a local coordinate system ,in: in: in: Step 5: Using the coordinate transformation formula, the coordinates of the inspection instrument T in the reference coordinate system are: : Sixth step: At the same time, the inspection instrument is also equipped with a power transmitter to build an electric field in the water environment of the foundation pit. The water surface buoy is also equipped with an electric field strength detector and an electric propeller multi-directional thruster. Once the electric field strength is too weak, it will autonomously cruise in four directions to find a position where the electric field strength meets the detection strength of the equipment. Step 7: At the same time, the water surface buoy array is also based on the reference point, and the coordinate position of each buoy is calculated in real time using a laser rangefinder to keep the angle difference of the triangle formed by the buoy array as little as possible to less than 30°. Step 8: At this point, a buoy array is used to enhance the local electric field, thereby automatically adapting to the position of the underwater inspection instrument and accurately capturing the coordinate position of the inspection instrument in real time.

[0027] This embodiment presents a wireless interactive and adaptive inspection instrument for underwater excavation of foundation pits and its operation method. The wireless interactive and adaptive inspection instrument has a reasonable overall design, simple structure, and convenient operation. The instrument body can acquire the attitude of the bottom marker and calculate the highest vertex and the midpoint of the highest edge. It activates the electric field strength detector and the point power transmitter at these two points. The interaction between the inspection instrument body and the bottom marker is realized through the electric field frequency of the point power. The instrument body activates the nearest bottom marker, acquires the coordinate position of the bottom marker, puts the bottom marker at the current position into a dormant state, moves the inspection position by one interval, and activates the bottom marker at the previous position to start the floating mechanism to complete the bottom marker retrieval. The cycle is repeated to complete the full coverage inspection of the entire bottom surface of the pit, realizing the adaptive placement, wireless interaction, and dynamic retrieval and reuse of the bottom marker.

[0028] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. A wireless autonomous positioning device for an underwater inspection robot in foundation pit construction, characterized in that, include A foundation pit is excavated on the ground. A retaining wall is set around the foundation pit. A mud-water layer and a mud slurry layer are distributed from top to bottom in the foundation pit. The mud slurry layer is located on the upper side of the bottom of the foundation pit. A reference point power supply array, comprising three or more reference point power supplies respectively set at positions around the perimeter of the underwater excavation pit above the water surface, to construct a reference coordinate system, and capable of transmitting point power supply electric field signals of different electric field frequencies into the pit one by one, with a laser rangefinder configured on one side of the reference point power supply to form a laser rangefinder array. A buoy array distributed on the water surface, the buoy array comprising buoys capable of constructing a planar rectangular coordinate system and arranged on the surface of the muddy water layer, wherein the laser rangefinder can measure the distance of each buoy in the water surface buoy array, thereby locating each buoy; An inspection instrument (100) is provided, which calculates the distance between power sources in the power source array relative to different reference points by detecting the electric field frequency and electric field strength; the inspection instrument (100) calculates the distance between different buoys by detecting the electric field frequency and electric field strength.

2. The wireless autonomous positioning device for underwater inspection robot in foundation pit construction as described in claim 1, characterized in that, The buoy includes a shell capable of floating on the surface of the muddy water layer. Inside the shell are an electric field strength detector, a buoy controller, and a power module. On the outside of the shell are an electric propeller multi-directional thruster and a buoy point power supply capable of moving the buoy to the required position. The buoy controller is communicatively connected to the electric field strength detector and the electric propeller multi-directional thruster, respectively. The power module is electrically connected to the electric field strength detector, the buoy controller, the buoy point power supply, and the electric propeller multi-directional thruster, respectively.

3. The wireless autonomous positioning device for underwater inspection robot in foundation pit construction as described in claim 1, characterized in that, The inspection device (100) includes a head cover (110), a central rod (120), and a base (130) with an overall cross structure. The central rod (120) is located between the head cover (110) and the base (130).

4. The wireless autonomous positioning device for underwater inspection robot in foundation pit construction as described in claim 3, characterized in that, The helmet (110) is equipped with a top electric field strength detector (111), a hydraulic detector (112), a buoyancy control module (113), a ballast water tank (114), a thruster (116), a control processing host (115), a power supply module (118), and an electric field signal control module (119). The ballast water tank (114) is located at the upper end of the helmet (110). The hydraulic detector (112) and the buoyancy control module (113) are located inside the ballast water tank (114). The top electric field strength detector (111) is located at the top of the ballast water tank (114). The thrusters (116) are symmetrically arranged on both sides of the helmet (110). The control processing host (115), power supply module (118), and electric field signal control module (119) are all located inside the head cover (110). The control processing host (115) is communicatively connected to the top electric field strength detector (111), hydraulic detector (112), buoyancy control module (113), ballast water tank (114), thruster (116), and electric field signal control module (119), respectively. The power supply module (118) is electrically connected to the top electric field strength detector (111), hydraulic detector (112), buoyancy control module (113), thruster (116), control processing host (115), and electric field signal control module (119), respectively.

5. A positioning method for a wireless autonomous positioning device for an underwater inspection robot in foundation pit construction, specifically for foundation pits with limited area, wherein the positioning method is based on the wireless autonomous positioning device for an underwater inspection robot in foundation pit construction as described in any one of claims 1-4, characterized in that... include: First step: Set up three reference power sources. The electrical signals emitted by the three power sources O, A, and B have frequencies of freq1, freq2, and freq3, respectively. Assume that they are directly arranged to form a rectangular coordinate system with the origin at O ​​and three orthogonal coordinate axes OX, OY, and OZ, where point O is at coordinates (0, 0, 0), point A is at coordinates (a, 0, 0), and point B is at coordinates (0, b, 0). The second step: The underwater inspection device is equipped with an electric field frequency detector and an electric field strength detector. The frequency of the electric signal, freq1, freq2, and freq3, is measured by the electric field frequency detector to identify which point power source, O, A, or B, the signal originates from. The electric field strength detector can measure the electric field strength E(r) at this point. For a point power source in a uniform medium, its electric field strength distribution is directly proportional to the resistivity ρ and the current I, and inversely proportional to the square of the distance, d^2. Where ρ is the resistivity of the liquid, I is the total current flowing from the point source, r is the distance to the point source, and E(d) is the magnitude of the electric field intensity; the formula can be used to calculate: Based on the above method for calculating the distance r and the method for distributing the electric field source, it can be known that the distances between the underwater inspection instrument P and points O, A, and B are d_op, d_ap, and d_bp, respectively. Then, based on geometric principles, the coordinates of point P in a given coordinate system can be calculated: Thus, the method for locating the inspection instrument in the relatively homogeneous upper mud and water layer (approximately tens of meters high) can be determined.

6. A positioning method for a wireless autonomous positioning device for an underwater inspection robot in foundation pit construction, targeting large-area foundation pits, wherein the positioning method is based on the wireless autonomous positioning device for an underwater inspection robot in foundation pit construction as described in any one of claims 1-4, characterized in that... include First step: Set up three reference power sources. The electrical signals emitted by the three power sources O, A, and B have frequencies of freq1, freq2, and freq3, respectively. Assume that they are directly arranged to form a rectangular coordinate system with the origin at O ​​and three orthogonal coordinate axes OX, OY, and OZ, where point O is at coordinates (0, 0, 0), point A is at coordinates (a, 0, 0), and point B is at coordinates (0, b, 0). Buoys P1, P2, and P3 are scattered on the water surface at a certain distance. The angle difference of the triangle formed by the three buoys should not be too large. Set up laser rangefinders at the positions of the three power sources O, A, and B to obtain the absolute distance D = dop,i, dap,i, dbp,i (i = 1, 2, 3) between the three power sources and the three buoys. Second step: The first layer (reference coordinate system) OAB plane, this plane is used as the XY plane (i.e., z = 0), P i The formula for the coordinates of the buoy point in the reference coordinate system is the same as in Case 1 above. Third step: Construct a local coordinate system with P1, P2, and P3 (with P1 as the origin and P1 and P2 as the x-axis): Fourth step: The inspection instrument T determines the distance d between itself and the three buoy points P1, P2, and P3 using the electric field strength measurement method described above. tp,i (i = 1, 2, 3), in the local coordinate system constructed with P1, P2, P3, the coordinates T loc =[x loc ,y loc ,z loc ] T ,in: in: in: Step 5: Using the coordinate transformation formula, the coordinates of the inspection instrument T in the reference coordinate system are T = [x, y, z]. T : Sixth step: At the same time, the inspection instrument is also equipped with a power transmitter to build an electric field in the water environment of the foundation pit. The water surface buoy is also equipped with an electric field strength detector and an electric propeller multi-directional thruster. Once the electric field strength is too weak, it will autonomously cruise in four directions to find a position where the electric field strength meets the detection strength of the equipment. Step 7: At the same time, the water surface buoy array is also based on the reference point, and the coordinate position of each buoy is calculated in real time using a laser rangefinder to keep the angle difference of the triangle formed by the buoy array as little as possible to less than 30°. Step 8: At this point, a buoy array is used to enhance the local electric field, thereby automatically adapting to the position of the underwater inspection instrument and accurately capturing the coordinate position of the inspection instrument in real time.

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