Acousto-optic combined detection method for multi-angle inclined surface damage of underwater facility

Abstract

The invention provides an acousto-optic combined detection method for multi-angle inclined surface damage of an underwater facility, and belongs to the technical field of tests and tests. The method has the advantages that the problems that the influence of water quality on multi-angle inclined surface damage of underwater facilities is large when an optical means is adopted, the detection efficiency is low, and the detection resolution is low when a traditional image sonar means is adopted are solved. An acousto-optic combined detection module composed of a side-scan sonar, a ranging sonar and an underwater optical camera is carried in the detection direction of an underwater carrier, and a rotation steering engine in the pitching direction controls the overturning angle of the detection module, so that the detection direction of acousto-optic detection equipment is perpendicular to surfaces to be detected at different inclination angles. And the rotation of the side-scan sonar array is controlled by a rotary steering engine in the rolling direction relative to the pitching angle, so that the installation direction of the array is consistent with the maneuvering direction of the underwater carrier, and the maneuvering state of the carrier is controlled according to the data of the distance measurement sonar to keep the consistent distance from the detection mechanism to the surface of the facility, so as to obtain a high-resolution acoustic image. A suspected area where the damage is located is judged through an acoustic image, and after the carrier approaches, an optical camera and an underwater light source are adopted for sequentially photographing and judging suspected positions, so that the surface damage condition of the underwater facility is determined.

Description

Technical Field

[0001] The present invention specifically designs a method for combining acoustic and optical detection of multi-angle inclined surface damage of underwater facilities, which involves underwater target acoustic detection and underwater optical detection technology and belongs to the field of experiment and testing technology. Background Art

[0002] Major facilities in my country, such as reservoirs, dams, ports and terminals, are affected by human factors such as design and construction, as well as natural influences such as biological and seawater corrosion, water erosion, and temperature changes during long-term use, resulting in cracks, dissolution, leakage and other phenomena, thus forming a series of structural damages. If the damage is not repaired in time, it will expand and pose a serious threat to major underwater facilities.

[0003] Manual inspection and underwater optical inspection equipment are commonly used methods for dam surface flaw detection. Usually, divers are equipped with optical cameras or underwater platforms are equipped with equipment such as underwater cameras to record the damage of local areas of underwater facilities. However, the manual inspection area is limited by the water depth. Under actual hydrological conditions, the working distance of optical inspection equipment varies greatly due to the clarity of the water area, and the low detection efficiency makes the robustness of the overall detection system not guaranteed. In recent years, underwater image sonar systems have also been used to obtain cracks on the surface of underwater facilities. Image sonar uses sound waves to detect underwater targets, which can greatly reduce the impact of water clarity. However, the detection distance of traditional image sonar is limited, and the acoustic resolution is not high enough, resulting in insufficient data required for subsequent recognition and processing.

[0004] When detecting surface damage of underwater facilities, a method for detecting surface damage of underwater facilities based on an underwater moving carrier equipped with underwater high-resolution acoustic detection equipment and optical detection equipment and combined with a rotating servo can be designed. The rotating servo controls the direction of the acoustic and optical detection equipment to meet the detection conditions of the high-resolution acoustic detection equipment and the optical detection equipment, obtains the acoustic image of the surface of the underwater facility and determines the approximate location of the damage, and then obtains the optical image information of the damage after the subsequent carrier approaches. Summary of the invention

[0005] The purpose of the present invention is to provide a method for combining acoustic and optical detection of multi-angle inclined surface damage of underwater facilities, which solves the problem of low efficiency and insufficient robustness of traditional optical means for detecting multi-angle inclined surface damage of underwater facilities.

[0006] In order to solve the above technical problems, the technical solution of the present invention is:

[0007] Firstly, an underwater robot is selected as an underwater mobile carrier for acoustic and optical detection of surface damage on inclined dam surface. An acoustic and optical detection module for underwater facility surface composed of side scan sonar, ranging sonar and underwater optical camera is installed at the front end of the carrier. The detection module is controlled by a rotating servo in the pitch direction (defined by Euler angle) and the roll direction relative to the pitch angle. The two arrays of the side scan sonar are installed in parallel on both sides of the rotating platform in the roll direction ( Figure 1 ), and the roll direction is controlled by the rotation servo in the roll direction relative to the pitch angle ( Figure 2 ), underwater optical cameras and ranging sonars are installed on the upper and lower sides near the center of the detection module ( Figure 1 ), does not rotate the platform in the rolling direction ( Figure 2 ), but at the same time as the platform is rotating in the rolling direction, it is also controlled by the pitch servo to rotate the pitch angle ( Figure 3 ), the underwater light source irradiation direction is divided into two directions: the front and the bottom of the underwater robot ( Figure 1 ).

[0008] When detecting damage on the inclined surface of underwater facilities, the high-precision acoustic detection equipment selects the side-scan sonar and ranging sonar with higher acoustic resolution, and controls the detection module to pitch to the same inclination angle as the surface to be tested through the pitch servo, so that the beams of the side-scan sonar array and the ranging sonar are vertically irradiated to the detection target surface ( Figure 4 ), through the vertical distance from the detection module to the inclined surface of the underwater facility, the underwater robot is controlled to keep the distance from the side scan sonar to the surface to be tested consistent during movement. The rotary servo in the rolling direction controls the rotation of the rotating platform to make the direction of the side scan sonar array consistent with the maneuvering direction of the underwater robot, so as to meet the high-precision detection conditions of the side scan sonar on the surface of the underwater facility distributed in this direction. The underwater robot keeps moving to carry out acoustic detection. According to the principle of side scan sonar, there will be strong echoes at concave and convex positions. Look for strong bright spot areas on the acquired acoustic image, analyze and determine the approximate location of the facility surface where the bright spot area is located, and after the underwater robot approaches, use the underwater optical camera to obtain optical images to carry out damage determination detection.

[0009] The effects and benefits of the present invention are that the acoustic signal has strong penetration in water and is less disturbed by floating materials in the water. The side-scan sonar detection has the advantages of wide area, fast speed, high resolution, high efficiency, etc., and the detection direction of the equipment can be changed by rotating the servo to obtain acoustic images of the surface of the underwater facility at different inclination angles, and the approximate location of the surface damage of the facility can be quickly determined. After the robot quickly approaches the damaged area, optical means are used to obtain image information of the damaged part to detect the damaged part of the underwater facility. The method improves the detection efficiency, accuracy and resistance to water quality interference of the surface damage of the underwater facility at different inclination angles, and after flipping down 90°, the bottom target of the water area near the underwater facility can be detected by combining sound and light, which increases the applicability of underwater detection targets. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Attached Figure 1 It is a schematic diagram of the structure of the acoustic-optical combined detection module device carried by the underwater robot in the present invention;

[0011] Attached Figure 2 This is a schematic diagram of the steering gear controlling the combined sound and light detection module in the rolling direction of the present invention rotating 90°;

[0012] Attached Figure 3 It is a schematic diagram of a 90° pitch flip of the steering gear control sound and light combined detection module in the pitch direction of the present invention;

[0013] Attached Figure 4 It is a schematic diagram of the method for combining sound and light to detect damage on the multi-angle inclined surface of underwater facilities in the present invention;

[0014] The reference numerals in the figure are as follows: 1-rotating platform; 2-side scan sonar array; 3-ranging sonar; 4-underwater optical camera; 5-underwater light source; 6-rotating servo in the rolling direction; 7-rolling rotation direction; 8-pitch flip; A is the center position of the acoustic-optical combined detection module; B is the vertical surface damage of the underwater facility; C is the inclined surface damage of the underwater facility; d is the installation spacing of the side scan sonar array; d1 is the vertical distance from the center of the side scan sonar to the vertical surface damage of the underwater facility; d2 is the vertical distance from the center of the side scan sonar to the inclined surface damage of the underwater facility; DETAILED DESCRIPTION

[0015] The specific implementation of the present invention is described in detail below in conjunction with the technical scheme and the accompanying drawings.

[0016] Step 1:

[0017] An underwater robot is used as an underwater mobile carrier for acoustic and optical detection of surface damage on inclined dams. The acoustic and optical detection module is installed in front of the robot. The two side-scan sonar arrays are installed in parallel on both sides of the rotating platform in the rolling direction. The distance d between the two side-scan acoustic arrays must meet the performance indicators of the normal operation of the side-scan sonar. The underwater optical camera and the ranging sonar are installed on the upper and lower sides of the center of the detection module, respectively, and form an acoustic and optical detection module with the rotating platform equipped with the side-scan sonar. The servo is installed to control the rotation of the platform carrying the side-scan sonar array, and the servo is installed to control the flipping of the acoustic and optical detection module in the pitch direction.

[0018] Step 2:

[0019] When detecting surface damage at different inclination angles of underwater facilities, after determining the surface to be detected of the facility, the detection module is controlled by the roll steering gear to flip the pitch angle, and the detection direction is controlled to be toward the surface to be detected, so that the side scan sonar array is parallel to the surface to be detected. The rotation angle can be determined by the facility construction drawings mastered in advance or roughly judged by the echo intensity at the same distance on the left and right sides displayed in the side scan sonar display and control software. When the echo intensity at the same distance on both sides is similar, it can be roughly determined that the sonar array is parallel to the surface to be detected. Then, the vertical distance d1 or d2 from the center A of the side scan sonar to the damage point B or C on the surface to be detected is obtained by the ranging sonar. The vertical distance d1 or d2 is kept as unchanged as possible during the acoustic side scan detection by controlling the underwater carrier maneuvering mode to achieve the best side scan detection effect.

[0020] Step 3:

[0021] According to the size of the surface to be inspected of the underwater facility, a suitable inspection path is set. Usually, two uniform speed maneuvers are adopted: along the vertical direction or the horizontal direction parallel to the surface to be inspected. According to the inspection maneuvering method and the side-scan sonar detection principle, the side-scan sonar has high acoustic wave resolution in the direction of the acoustic array distribution, and is consistent with the sonar side-scan inspection maneuvering direction. Therefore, the rotating platform on which the side-scan sonar is installed is rotated by controlling the rotation of the rotating servo in the roll direction relative to the pitch angle, so that the installation direction of the side-scan sonar acoustic array and the maneuvering direction of the underwater carrier parallel to the surface to be inspected are consistent, so that a high-resolution acoustic image distributed in this direction can be obtained. Subsequently, the detection platform direction can be changed by rotating the servo to be consistent with the changed maneuvering direction of the underwater carrier, so as to obtain high-resolution acoustic images in different directions.

[0022] Step 4:

[0023] After rapid maneuvering to detect the acoustic image of the surface to be detected, the acoustic image result is obtained through side scanning. According to the principle of side scanning, there will be strong reflection echoes at uneven positions, and they will be displayed on the interface in the form of strong bright spots. In the acoustic image, the left and right positions of the target area on the carrier's maneuvering route and the approximate position of the detection area can be judged based on the strong bright spot area. After determining that the suspected damage is located in the approximate area of ​​the surface to be detected, the underwater carrier will make an approaching maneuver. After reaching the target area, the brightness of the underwater light source is adjusted according to the clarity of the optical image of the facility surface fed back from the underwater optical camera vertically facing the surface to be detected, and an optical image with high clarity and contrast is obtained. The suspected area is checked and detected based on the image, and the surface damage of the underwater facility is finally determined.

Claims

1. The method of combining acoustic and optical detection of multi-angle inclined surface damage of underwater facilities is to use an underwater motion platform equipped with underwater high-resolution acoustic and optical detection equipment, and two steering gears with different rotation directions jointly control the direction of the acoustic and optical detection equipment to efficiently detect surface damage at different inclined angles of underwater facilities. This method combines the acoustic detection equipment composed of side-scan sonar and ranging sonar with the optical detection equipment composed of underwater optical camera and underwater light source. The side arrays of the side-scan sonar are distributed in parallel on both sides of the detection module, and the optical camera and ranging sonar are installed on the upper and lower sides near the center of the detection module. The pitch direction rotating servo controls the detection module to rotate in the pitch direction, so that the detection directions of the acoustic detection equipment and the optical detection equipment are perpendicular to the surface of the underwater facility with different inclination degrees. The underwater motion platform maneuvers at a constant speed parallel to the surface to be measured along the direction of the side scan sonar array while maintaining a stable distance from the surface to be measured. The side scan sonar is controlled to rotate in the roll direction relative to the pitch angle by the roll direction rotating servo to obtain the acoustic image of the surface to be measured, and the approximate location of the damage is quickly identified and determined based on the acoustic image. When the underwater platform moves close to the damage location, the optical detection equipment is used to obtain optical image information of the damaged part on the surface of the underwater facility.

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