Dam underwater defect detection robot positioning method based on single beacon distance measurement

Abstract

The invention discloses a dam underwater defect detection robot positioning method based on single beacon distance measurement, and belongs to the technical field of underwater robot navigation positioning. According to the method, the problem that an underwater defect detection method in the existing marine environment is not suitable any more due to the particularity of a detection mode and a detection path when an underwater dam body detection robot carries out vertical dam surface detection is solved. According to the method, the characteristics of a detection mode and a detection path when the detection robot carries out vertical dam surface detection are fully considered, the method for realizing underwater positioning of the robot through the detection robot and the single beacon is designed, and due to the fact that only one acoustic beacon is needed, the complexity and the application cost of a positioning system are reduced. And the course information and the speed information of the detection robot and the position information of the detection robot at the previous moment do not need to be acquired, so that the data calculation amount is reduced, and the position calculation of the detection robot at each moment has high independence. The method can be applied to underwater robot positioning.

Description

Technical Field

[0001] The invention belongs to the technical field of underwater robot navigation and positioning, and in particular relates to a dam underwater defect detection robot positioning method based on single beacon ranging. Background Art

[0002] Domestic design specifications stipulate that dams with a height of 70m or more are high dams, dams with a height of 200m or more are extra-high dams, and dams with a height of 300m or more are mostly super-high dams. According to statistics, my country has 588 dams with a height of more than 70m, 223 dams with a height of more than 100m, and 23 extra-high dams with a height of more than 200m. It is the country with the most high dams and reservoirs in the world and the fastest development. Underwater defect detection of dam bodies is of great significance for the long-term safe operation and management of high dams and reservoirs. With the widespread application of underwater robots in various civil and military fields, underwater unmanned detection technology using underwater robots as carriers has gradually become one of the most effective ways in the field of dam body detection in addition to diver diving detection. At present, underwater unmanned detection technology mainly uses unmanned remote-controlled underwater robots (ROVs) as carriers, and comb-scans the underwater dam surface by carrying relevant equipment to achieve underwater environment construction and dam body defect detection. In this process, the first problem to be solved is the navigation and positioning of underwater robots.

[0003] Due to the strong absorption and shielding effect of water on electromagnetic waves, the underwater propagation distance of electromagnetic waves is very limited, and the global navigation satellite system (GNSS) is no longer suitable for underwater navigation. Sound waves have become the main way to transmit underwater information, and underwater acoustic positioning technology has also become an important means of underwater navigation and positioning.

[0004] Traditional underwater acoustic positioning systems mainly include long baseline (LBL) systems and ultra-short baseline (USBL) systems. Traditional long baseline and ultra-short baseline underwater acoustic positioning systems have the characteristics of relatively complex structure, large number of beacons, small coverage area, low utilization efficiency, etc., which cannot meet the needs of long-term positioning; positioning technology based on single beacon ranging can simplify the positioning system structure, reduce the number of beacon calibrations, quantity and recycling costs, and improve the utilization efficiency of beacon nodes. It is the development trend of underwater navigation.

[0005] Due to the special requirements of underwater dam inspection robots when conducting vertical dam surface inspection, the application environment of underwater dam defect inspection in water conservancy projects is very different from that in marine engineering. Therefore, it is not feasible to simply transplant underwater technology in the marine environment to the dam environment. It is necessary to develop new technologies to adapt to the special water environment of reservoir dams in a unique way. Summary of the invention

[0006] The purpose of the present invention is to solve the problem that the existing underwater inspection robot positioning method in the marine environment is no longer applicable due to the special needs of the underwater dam body inspection robot when performing vertical dam surface inspection, and proposes a dam underwater defect inspection robot positioning method based on single beacon ranging.

[0007] The technical solution adopted by the present invention to solve the above technical problems is:

[0008] A dam underwater defect detection robot positioning method based on single beacon ranging, the method specifically comprises the following steps:

[0009] Step 1: After placing the beacon on the water surface, establish a navigation coordinate system with the beacon center as the origin O, and obtain the position information of the beacon in the geodetic coordinate system (L0, λ0, d0) by calibrating the beacon, where L0 is the latitude of the beacon, λ0 is the longitude of the beacon, and d0 is the depth of the beacon;

[0010] Step 2: After the detection robot navigates into the range of the beacon, the detection robot establishes acoustic communication with the beacon, obtains the distance information between the detection robot and the beacon, and controls the detection robot to navigate toward the beacon according to the obtained distance information;

[0011] Draw a vertical line from the beacon center to the dam surface to be inspected, and then control the inspection robot to sail from the beacon along the drawn vertical line to the dam surface to be inspected. When the inspection robot sails to position P, obtain and record the distance information R0 between the inspection robot and the beacon;

[0012] The position P satisfies: the vertical distance from the position P to the dam surface to be inspected is equal to the detection distance of the inspection robot;

[0013] Step 3: The detection robot performs comb scanning detection on the vertical dam surface at a fixed distance from the vertical dam surface. At time t1 during the comb scanning detection process, the position information of the detection robot at time t1 is calculated based on the position information of the beacon in the geodetic coordinate system, the distance information R0, the azimuth angle information of the dam surface, the depth information of the detection robot at time t1, and the distance information between the detection robot and the beacon at time t1;

[0014] Step 4: Fuse the detection robot position information calculated in step 3 with the detection robot position information output by the inertial navigation system to obtain the final positioning information of the detection robot at time t1.

[0015] The beneficial effects of the present invention are:

[0016] (1) The present invention is aimed at the application environment of the underwater dam body inspection robot, fully considers the special needs of the inspection robot when performing vertical dam surface inspection, designs the inspection method and inspection path of the present invention, and designs a method for realizing underwater positioning of the robot by using the inspection robot and a single beacon based on the inspection method and inspection path. Compared with the traditional acoustic positioning system, only one acoustic beacon is needed in the method of the present invention, which reduces the complexity and application cost of the entire positioning system.

[0017] (2) Compared with the traditional single beacon positioning method, the method of the present invention does not need to obtain the heading information, speed information and the position information of the robot detected at the previous moment, which reduces the amount of data calculation. At the same time, since the position information of the robot detected at the previous moment is not required, the position calculation output of the robot detected at each moment in the method of the present invention maintains a high degree of independence. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a flow chart of a positioning method of a dam underwater defect detection robot based on single beacon ranging of the present invention;

[0019] Figure 2 is a schematic diagram of a two-dimensional coordinate system;

[0020] Figure 3 This is a schematic diagram of the minimum distance between the beacon and the comb scanning path;

[0021] Figure 4 It is a schematic diagram of the comb scanning detection process;

[0022] Figure 5 Schematic diagram of coordinate transformation;

[0023] Figure 6 Schematic diagram of the two-dimensional coordinate system solution method. DETAILED DESCRIPTION

[0024] Specific implementation method 1: Combination Figure 1 This embodiment describes a method for positioning a robot for underwater defect detection of dams based on single beacon ranging, and the method specifically includes the following steps:

[0025] Step 1: After placing the beacon on the water surface, establish a navigation coordinate system with the beacon center as the origin O, and obtain the position information of the beacon in the geodetic coordinate system (L0, λ0, d0) by calibrating the beacon, where L0 is the latitude of the beacon, λ0 is the longitude of the beacon, and d0 is the depth of the beacon;

[0026] In the present invention, it is necessary to wait until the state of the surface beacon is stable, and then use the USBL system carried by the mother ship to calibrate the beacon;

[0027] Step 2: After the detection robot navigates into the range of the beacon, the detection robot establishes acoustic communication with the beacon, obtains the distance information between the detection robot and the beacon, and controls the detection robot to navigate toward the beacon according to the obtained distance information;

[0028] Draw a vertical line from the beacon center to the dam surface to be inspected (the dam surface itself is vertical), and then control the inspection robot to navigate from the beacon (i.e. the origin of the navigation coordinate system) along the drawn vertical line to the dam surface to be inspected, such as Figure 3 As shown, when the detection robot navigates to position P, the distance information R0 between the detection robot and the beacon is obtained and recorded;

[0029] The position P satisfies: the vertical distance from the position P to the dam surface to be inspected is equal to the detection distance of the inspection robot;

[0030] Step 3: Figure 4 As shown, the detection robot performs comb scanning detection on the vertical dam surface at a fixed distance from the vertical dam surface (the fixed distance here is the detection distance of the detection robot). At time t1 in the comb scanning detection process, the position information of the detection robot at time t1 is calculated based on the position information of the beacon in the geodetic coordinate system, the distance information R0, the azimuth angle information of the dam surface, the depth information of the detection robot at time t1, and the distance information between the detection robot and the beacon at time t1;

[0031] Step 4: Fuse the detection robot position information calculated in step 3 with the detection robot position information output by the inertial navigation system to obtain the final positioning information of the detection robot at time t1.

[0032] The method of the present invention can be used to obtain positioning information at each moment in the comb scanning detection process, and the single beacon positioning system ends its work when the detection robot completes its task and floats up or leaves the action range of the current beacon.

[0033] In order to cope with the special requirements of the underwater dam body inspection robot in vertical dam surface inspection, the present invention designs corresponding inspection methods and inspection paths.

[0034] In terms of detection method design, the present invention fully considers the complexity of the underwater environment and the limitations of sound wave propagation, especially when detecting vertical dam surfaces, a comb scanning detection mode is adopted. This mode can ensure that the robot covers a larger detection area within a fixed detection distance, ensure that possible defects are not missed, and improve the accuracy and efficiency of the overall detection.

[0035] In terms of detection path design, the present invention plans the shortest path from the beacon to the dam surface for the detection robot. At the same time, during the detection process, the robot maintains a motion trajectory parallel to the dam surface along a fixed detection distance. This path design helps to ensure that the robot always maintains an appropriate distance from the dam surface to avoid affecting the detection accuracy due to distance fluctuations. At the same time, the positioning algorithm is simplified through path planning, making the positioning solution at each moment more accurate and stable.

[0036] This design combines the particularities of the underwater environment and the needs of dam inspection, ensuring the accuracy and efficiency of the inspection.

[0037] Specific implementation method 2: This implementation method is different from the specific implementation method 1 in that the navigation coordinate system takes the north direction as x n The positive direction of the axis, with the east direction as y n The positive direction of the axis, with the earth direction as z n Positive axis direction.

[0038] The other steps and parameters are the same as those in the first embodiment.

[0039] Specific implementation method three: This implementation method is different from specific implementation methods one or two in that the specific process of step three is as follows:

[0040] Step 31: The distance between the detection robot and the beacon at time t1 is recorded as L1, and the depth of the detection robot at time t1 is recorded as d1. The depth d1 is obtained by the depth meter. The depth difference Δh between the detection robot and the beacon at time t1 is calculated based on d0 and d1;

[0041] Step 32: Calculate the projection distance R1 of the distance L1 in the two-dimensional coordinate system xoy according to the depth difference Δh;

[0042] The origin of the two-dimensional coordinate system xoy is the beacon center, and the x-axis direction is the same as the x-axis direction of the navigation coordinate system. n The y-axis direction is the same as the x-axis direction of the navigation coordinate system. n The axis directions are the same;

[0043] Step 3: Calculate the angle α1 between the vertical line from the beacon to the dam surface and the line connecting the beacon and the detection robot at time t1 according to the projection distance R1 and the distance information R0;

[0044] Step 3 and 4: Calculate the position (x1, y1) of the detection robot in the two-dimensional coordinate system xoy at time t1 according to the projection distance R1, the dam surface azimuth and the angle α1. The two-dimensional coordinate system is as follows: Figure 2 shown.

[0045] The other steps and parameters are the same as those in the first or second embodiment.

[0046] Specific implementation method 4: This implementation method is different from any one of the specific implementation methods 1 to 3 in that at time t1, the depth difference between the detection robot and the beacon is:

[0047] Δh=d1-d0

[0048] The other steps and parameters are the same as those in Specific Embodiments 1 to 3.

[0049] Specific implementation method five: Combination Figure 5 This embodiment is different from the first to fourth embodiments in that the specific process of step three-two is as follows:

[0050]

[0051] The other steps and parameters are the same as those in Specific Embodiments 1 to 4.

[0052] Specific implementation method six: This implementation method is different from any one of specific implementation methods one to five in that the dam surface azimuth information is the angle between the vertical line of the dam surface and the north direction, and the dam surface azimuth is recorded as θ.

[0053] The other steps and parameters are the same as those in Specific Implementation Methods 1 to 5.

[0054] In the present invention, the dam surface azimuth information can be obtained by the dam operation and management office.

[0055] Specific implementation method 7: This implementation method is different from specific implementation methods 1 to 6 in that the specific process of step 33 is as follows:

[0056] α1=arccos(R0 / R1)

[0057] The other steps and parameters are the same as those in Specific Embodiments 1 to 6.

[0058] Specific implementation method eight: Combination Figure 6 This embodiment is different from the first to seventh embodiments in that the specific process of steps three and four is as follows:

[0059]

[0060] The other steps and parameters are the same as those in Specific Embodiments 1 to 7.

[0061] Specific implementation method 9: This implementation method is different from specific implementation methods 1 to 8 in that the specific process of step 4 is as follows:

[0062] Process the position information of the detection robot at time t1:

[0063]

[0064] Among them, R M is the meridian curvature radius, R N is the radius of curvature of the Maoyou circle;

[0065] The position information (L1, λ1, d1) of the detection robot in the geodetic coordinate system at time t1 is taken as the observation quantity, and the position information of the detection robot output by the inertial navigation system at time t1 is taken as the state quantity. The observation quantity and the state quantity are fused using the nonlinear filtering method, and the fusion result is taken as the corrected position information of the detection robot at time t1, that is, the final positioning information of the detection robot is obtained.

[0066] The other steps and parameters are the same as those in Specific Embodiments 1 to 8.

[0067] Specific implementation method ten: This implementation method is different from any one of specific implementation methods one to nine in that the nonlinear filtering method is a Kalman filtering method or a particle filtering method.

[0068] The other steps and parameters are the same as those in Specific Embodiments 1 to 9.

[0069] The nonlinear filtering method adopted in this embodiment includes but is not limited to Kalman filtering or particle filtering method.

[0070] Example

[0071] like Figure 1 As shown, this embodiment proposes a dam underwater defect detection robot positioning method based on single beacon ranging, which specifically includes the following steps 1 to 4. The following steps 1 to 4 are described as follows:

[0072] Step 1: After placing the beacon on the water surface, establish a navigation coordinate system with the beacon center as the origin O, and the navigation coordinate system takes the north direction as x n The positive direction of the axis, with the east direction as y n The positive direction of the axis, with the earth direction as z n Axis positive direction;

[0073] After the surface beacon is stable, the USBL system on the mother ship is used to calibrate the beacon; the position information (L0, λ0, d0) of the beacon in the geodetic coordinate system is determined by taking the average value, where L0 is the latitude of the beacon, λ0 is the longitude of the beacon, and d0 is the depth of the beacon;

[0074] Step 2: When the detection robot sails into the range of the beacon, the detection robot establishes acoustic communication with the beacon, obtains the distance information between the detection robot and the beacon, and controls the detection robot to sail toward the beacon according to the obtained distance information;

[0075] Draw a vertical line from the beacon center to the dam surface to be inspected, and then control the inspection robot to navigate from the beacon (i.e. the origin of the navigation coordinate system) along the drawn vertical line to the dam surface to be inspected. Figure 3 As shown, when the vertical distance from the detection robot to the vertical dam surface to be detected is equal to the detection distance of the detection robot, the distance information R0 between the detection robot and the beacon is obtained and recorded;

[0076] Step 3: Figure 4 As shown in the figure, the detection robot performs comb scanning detection on the vertical dam surface at a fixed distance from the vertical dam surface (the fixed distance here is the detection distance of the detection robot), the distance between the detection robot and the beacon at time t1 is recorded as L1, the depth of the detection robot at time t1 is recorded as d1, the depth d1 is obtained by the depth meter, and the depth difference Δh between the detection robot and the beacon at time t1 is calculated based on d0 and d1:

[0077] Δh=d1-d0

[0078] like Figure 2 As shown, establish the x-axis direction and navigation coordinate system with the beacon center as the origin n The y-axis direction is the same as the x-axis direction of the navigation coordinate system. n The two-dimensional coordinate system xoy with the same axial direction, the projection distance R1 of the distance L1 in the two-dimensional coordinate system xoy is calculated according to the depth difference Δh;

[0079]

[0080] According to the projection distance R1 and the distance information R0, the included angle α1 between the vertical line from the beacon to the dam surface and the line connecting the beacon and the detection robot at time t1 is calculated;

[0081] α1=arccos(R0 / R1)

[0082] According to the projection distance R1, the dam surface azimuth and the angle α1, the position (x1, y1) of the detection robot in the two-dimensional coordinate system xoy at time t1 is calculated;

[0083]

[0084] Step 4: Process the detection robot position information calculated in step 3:

[0085]

[0086] Among them, R M is the meridian curvature radius, R N is the radius of curvature of the Maoyou circle;

[0087] The position information (L1, λ1, d1) of the detection robot in the geodetic coordinate system at time t1 is taken as the observation quantity, and the position information of the detection robot output by the inertial navigation system at time t1 is taken as the state quantity. The observation quantity and the state quantity are fused using nonlinear filtering methods such as Kalman filtering or particle filtering methods, and the fusion result is taken as the corrected position information of the detection robot at time t1, so as to obtain the final positioning information of the detection robot.

[0088] The method of this embodiment can be used to obtain positioning information at each moment in the detection process. When the detection robot completes the task and floats up or leaves the range of the current beacon, the single beacon positioning system ends its work.

[0089] The above calculation examples of the present invention are only used to explain the calculation model and calculation process of the present invention in detail, and are not intended to limit the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A dam underwater defect detection robot positioning method based on single beacon ranging, characterized in that: The method specifically comprises the following steps: Step 1: After placing the beacon on the water surface, establish a navigation coordinate system with the beacon center as the origin O, and obtain the position information of the beacon in the geodetic coordinate system (L0, λ0, d0) by calibrating the beacon, where L0 is the latitude of the beacon, λ0 is the longitude of the beacon, and d0 is the depth of the beacon; Step 2: After the detection robot navigates into the range of the beacon, the detection robot establishes acoustic communication with the beacon, obtains the distance information between the detection robot and the beacon, and controls the detection robot to navigate toward the beacon according to the obtained distance information; Draw a vertical line from the beacon center to the dam surface to be inspected, and then control the inspection robot to sail from the beacon along the drawn vertical line to the dam surface to be inspected. When the inspection robot sails to position P, obtain and record the distance information R0 between the inspection robot and the beacon; The position P satisfies: the vertical distance from the position P to the dam surface to be inspected is equal to the detection distance of the inspection robot; Step 3: The detection robot performs comb scanning detection on the vertical dam surface at a fixed distance from the vertical dam surface. At time t1 during the comb scanning detection process, the position information of the detection robot at time t1 is calculated based on the position information of the beacon in the geodetic coordinate system, the distance information R0, the azimuth angle information of the dam surface, the depth information of the detection robot at time t1, and the distance information between the detection robot and the beacon at time t1; Step 4: Fuse the detection robot position information calculated in step 3 with the detection robot position information output by the inertial navigation system to obtain the final positioning information of the detection robot at time t1.

2. The method for positioning a dam underwater defect detection robot based on single beacon ranging according to claim 1 is characterized in that: The navigation coordinate system takes north as x n The positive direction of the axis, with the east direction as y n The positive direction of the axis, with the earth direction as z n Positive axis direction.

3. The method for positioning a dam underwater defect detection robot based on single beacon ranging according to claim 1 is characterized in that: The specific process of step three is: Step 31: record the distance between the detection robot and the beacon at time t1 as L1, record the depth of the detection robot at time t1 as d1, and calculate the depth difference Δh between the detection robot and the beacon at time t1 based on d0 and d1; Step 32: Calculate the projection distance R1 of the distance L1 in the two-dimensional coordinate system xoy according to the depth difference Δh; The origin of the two-dimensional coordinate system xoy is the beacon center, and the x-axis direction is the same as the x-axis direction of the navigation coordinate system. n The y-axis direction is the same as the x-axis direction of the navigation coordinate system. n The axis directions are the same; Step 3: Calculate the angle α1 between the vertical line from the beacon to the dam surface and the line connecting the beacon and the detection robot at time t1 according to the projection distance R1 and the distance information R0; Step 34: Calculate the position (x1, y1) of the detection robot in the two-dimensional coordinate system xoy at time t1 based on the projection distance R1, the dam surface azimuth and the angle α1.

4. The method for positioning a dam underwater defect detection robot based on single beacon ranging according to claim 3 is characterized in that: At time t1, the depth difference between the detection robot and the beacon is: Δh=d1-d0.

5. The method for positioning a dam underwater defect detection robot based on single beacon ranging according to claim 3 is characterized in that: The specific process of step 32 is as follows:

6. The method for positioning a dam underwater defect detection robot based on single beacon ranging according to claim 3 is characterized in that: The dam surface azimuth information is the angle between the vertical line of the dam surface and the north direction, and the dam surface azimuth is recorded as θ.

7. The method for positioning a dam underwater defect detection robot based on single beacon ranging according to claim 1, characterized in that: The specific process of step 33 is as follows: α1=arccos(R0 / R1).

8. The method for positioning a dam underwater defect detection robot based on single beacon ranging according to claim 6 is characterized in that: The specific process of steps three and four is as follows:

9. The method for positioning a dam underwater defect detection robot based on single beacon ranging according to claim 3 is characterized in that: The specific process of step 4 is as follows: Process the position information of the detection robot at time t1: Among them, R M is the meridian curvature radius, R N is the radius of curvature of the Maoyou circle; The position information (L1, λ1, d1) of the detection robot in the geodetic coordinate system at time t1 is taken as the observation quantity, and the position information of the detection robot output by the inertial navigation system at time t1 is taken as the state quantity. The observation quantity and the state quantity are fused using the nonlinear filtering method, and the fusion result is taken as the corrected position information of the detection robot at time t1, that is, the final positioning information of the detection robot is obtained.

10. A dam underwater defect detection robot positioning method based on single beacon ranging according to claim 9, characterized in that: The nonlinear filtering method is a Kalman filtering method or a particle filtering method.

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