Multibeam sonar-based method for positioning and surveying underwater robot

Abstract

A multibeam sonar-based method for positioning and surveying an underwater robot. The method comprises: establishing a sonar coordinate system after an underwater robot equipped with a multibeam sonar enters a confined space (S1); performing scanning and ranging on a contour of the confined space by the underwater robot using the multibeam sonar, and representing a surveyed contour of the confined space using coordinate values of the sonar coordinate system (S2); in the confined space defined by the surveyed contour, performing real-time positioning of the underwater robot on the basis of coordinate values of the sonar coordinate system determined in real time by the multibeam sonar, so as to obtain positioning coordinate values (S3); and when the underwater robot uses captured images to perform end-surface surveying of the confined space, calibrating the images by using real-time positioning coordinate values of positions at which the images are captured; and stitching images captured for a same end surface by using calibration information, so as to complete surveying of end-surface information in its entirety (S4).

Description

underwater robot localization and surveying methods based on multibeam sonar

[0001] This application claims priority to Chinese Patent Application No. 202411907209.6, filed with the Chinese Patent Office on December 24, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application belongs to the fields of underwater robot technology and sonar positioning technology, for example, it relates to an underwater robot positioning and surveying method based on multibeam sonar. Background Technology

[0003] Currently, underwater robots employ sonar ranging-based positioning technology for water location. This involves establishing a three-dimensional base station by deploying multiple sonar transceivers underwater. This base station receives sonar waves emitted by the underwater robot and calculates the distances between the robot and each sonar transceiver to determine the robot's position relative to the base station. The base station connects to a ground-based communication satellite, and the robot's actual position is calculated by using the satellite's location to pinpoint the base station.

[0004] It is evident that this underwater positioning method is only suitable for locating underwater robots in open waters where satellite signals can be connected. However, when underwater robots are conducting surveys in enclosed, confined spaces, the transmission of sound waves underwater is interfered with by echoes, making it difficult for satellite communication positioning signals to reach the confined water space. This causes the underwater robot to be difficult to locate in confined water spaces, making it impossible for operators to promptly grasp the underwater robot's position in the confined water space and affecting the survey of the confined space. Summary of the Invention

[0005] This application discloses a method for underwater robot localization and surveying based on multibeam sonar, which solves the problem of positioning underwater robots in confined water spaces.

[0006] This application discloses a method for underwater robot localization and surveying based on multibeam sonar, including:

[0007] Establish a sonar coordinate system after the underwater robot equipped with a multibeam sonar enters a confined space; the sonar coordinate system takes the end face of one of the ranging sonars in the multibeam sonar as the origin, and uses the distances from the end faces of each wall in the confined space measured by the ranging sonar with the same orientation as the coordinate system to mark the coordinate values ​​of each axis.

[0008] The underwater robot scans and measures the contours of a limited space using multibeam sonar, and uses the coordinate values ​​of the sonar coordinate system to represent the survey contours of the limited space.

[0009] Within the limited space of the surveyed contour, the underwater robot is located in real time based on the coordinate values ​​of the sonar coordinate system determined in real time by the multibeam sonar, and the positioning coordinate values ​​are obtained.

[0010] When an underwater robot uses captured images to survey a confined space, the images are calibrated using real-time positioning coordinates. The calibration information is then used to stitch together images captured on the same end face to complete the survey of the entire end face.

[0011] In some embodiments, the multibeam sonar is a six-beam ranging sonar mounted on the bottom of the underwater robot, which, after mounting, forms five horizontal component ranging sonars parallel to the underwater robot body and one vertical component ranging sonar perpendicular to the underwater robot body.

[0012] Among them, the five horizontal component ranging sonars are the left front, right front, right, rear, and left ranging sonars; among them,

[0013] The left and right front ranging sonars are set on a plane parallel to the body of the underwater robot, facing the front of the underwater robot. The ranging positions of the left and right front ranging sonars are symmetrical to the front and rear central axes of the underwater robot, and are used to measure the distance from the underwater robot to the boundary of the confined space at their respective ranging positions.

[0014] The left, rear, and right ranging sonars are set on a plane parallel to the underwater robot body, facing the left, rear, and right sides of the underwater robot respectively, with ranging azimuths differing by 90 degrees; the left, rear, and right ranging sonars are used to measure the distance from the underwater robot to the boundary of the confined space at their respective ranging azimuths.

[0015] The vertical component ranging sonar is perpendicular to the underwater robot's body and faces the bottom of the confined space. It is used to measure the distance from the bottom of the underwater robot to the bottom of the confined space.

[0016] In some embodiments, the established sonar coordinate system is a four-axis coordinate system, in which the measurement end face of the rear ranging sonar is taken as the origin of the coordinate system, and the distance measurement axes of the left, rear, and right ranging sonars and the vertical component ranging sonar are used as the coordinate axes of the coordinate system.

[0017] In this context, the distance measurement axis of the ranging sonar will be the x-axis, and the distance measurement values ​​will be coordinates. With the distance measurement axis of the left ranging sonar as the positive y-axis, the distance measurement values ​​are on the coordinate system. With the distance measurement axis of the right ranging sonar as the negative y-axis, the distance measurement value is the coordinate... The distance measurement axis of the vertical component ranging sonar is taken as the z-axis, and the distance measurement value is the coordinate system. ;

[0018] The sonar coordinates of the underwater robot, marked by distance measurements from the rear, left, and right ranging sonars and the vertical component ranging sonar, are as follows: .

[0019] In some embodiments, the process of establishing a sonar coordinate system includes:

[0020] After the underwater robot enters the confined space, adjust the underwater robot's pitch attitude so that the underwater robot's pitch angle is the same as the axis tilt angle of the confined space, including the cable well; ensure that the rear, left, and right ranging sonars and the vertical component ranging sonar used for coordinate value marking are perpendicular to the sound wave reflecting wall of the confined space in the pitch direction.

[0021] The underwater robot's orientation and attitude are adjusted by using the ranging values ​​from the front wall of the confined space it faces, measured by the left and right front-range sonars; when the ranging values ​​of the left and right front-range sonars... , When they are equal, the underwater robot is perpendicular to the front wall of the limited space directly opposite its front end in the dimensional direction;

[0022] according to , When the values ​​are equal, the data returned by the underwater robot's attitude sensor marks the underwater robot's orientation and attitude at this time as the zero-point attitude.

[0023] Maintaining the zero-point attitude, the underwater robot is controlled to move left and right and rise and fall up and down by feedback from the ranging data of the rear, left and right ranging sonar and the vertical component ranging sonar until the fluctuation amplitude of the ranging data of the rear, left and right ranging sonar and the vertical component ranging sonar is less than the preset threshold, so as to avoid other objects in the limited space from obstructing the ranging process.

[0024] The sonar coordinates of the underwater robot are marked with distance measurements from the stable rear, left, and right ranging sonar and the vertical component ranging sonar. .

[0025] In some embodiments, the process of conducting contour surveying includes:

[0026] After establishing the sonar coordinate system, the underwater robot is translated to the first end face of the confined space while maintaining the zero-point attitude, so that the rear ranging sonar approaches the first end face as the starting position for contour surveying. The distance measurements of the rear, left, and right ranging sonars are recorded, where the distance measurement of the rear ranging sonar is the x-coordinate of the starting position of the contour surveying. The distance measurements from the left and right ranging sonars are the positive and negative y-coordinates of the starting position of the contour survey, respectively. , ;

[0027] Maintain the zero-point attitude, control the underwater robot to move forward along the positive x-axis of the sonar coordinate system, and record the distance measurements of the rear, left, and right ranging sonars until the underwater robot translates to the second end face opposite the first end face in a limited space;

[0028] Establish a Cartesian coordinate system, where the origin is the starting position of the contour survey, the horizontal axis is the x-axis of the sonar coordinate system, and the positive and negative half-axis of the vertical axis are the positive and negative y-axis of the sonar coordinate system. Mark the distance measurements of the left and right ranging sonars in the Cartesian coordinate system to form the boundary curves of the left and right contours of the finite space formed by the distance measurements of the left and right ranging sonars from the first end face to the second end face. Based on the boundary curves of the left and right contours, superimpose the first end face and the second end face to complete the survey of the finite space contour.

[0029] In some embodiments, within the limited space of the surveyed contour, the underwater robot is positioned in real time based on the coordinate values ​​of the sonar coordinate system determined in real time by multibeam sonar, to obtain positioning coordinate values, including:

[0030] Within the limited space of the survey profile, the coordinates of the underwater robot in the sonar coordinate system are determined in real time based on the ranging results of the multibeam sonar. ;

[0031] Measure the deflection angle B of the underwater robot relative to the zero-point attitude in terms of orientation;

[0032] Based on the deflection angle B and the coordinates in the sonar coordinate system To determine the position of the underwater robot within a confined space;

[0033] The underwater robot's position within a confined space satisfies:

[0034] Distance from the rear wall: ;

[0035] Distance from left wall: ;

[0036] Distance from the right wall: ;

[0037] Distance from bottom: ;

[0038] according to To achieve real-time positioning of underwater robots.

[0039] In some embodiments, the deflection angle B is calculated using trigonometric functions based on the ranging values ​​of the left front and right front ranging sonars to the front wall of the confined space, combined with the ranging azimuth of the left front or right front ranging sonar and the angle A between the front and rear central axis.

[0040] When the underwater robot deflects to the right relative to its zero-point attitude, the trigonometric function relationship satisfies:

[0041] ;

[0042] ;

[0043] When the underwater robot deflects to the left relative to its zero-point attitude, the trigonometric function relationship satisfies:

[0044] ;

[0045] .

[0046] In some embodiments, when an underwater robot uses captured images to conduct a limited-space end-face survey, the images are calibrated using real-time positioning coordinates of the captured image locations; the calibration information is then used to stitch together images captured from the same end-face to complete the survey of the entire end-face information, including:

[0047] During the survey of the confined space end face, the shooting position of the underwater robot is calibrated for each captured image; the shooting position is based on the coordinates of the sonar coordinate system at the time of shooting. The position of the underwater robot within a limited space is obtained by combining the deflection angle of the shooting position. ;

[0048] Calibration coordinates of multiple images taken from the same end face Image stitching is performed, where the value of i ranges from 1 to the total number of images captured on that end face; during the stitching process, multiple images are compared... Determine the field of view size for each image, through multiple images. , Determine the left-right relationships and overlaps between the images, using multiple images... Determine the vertical relationship between the images;

[0049] Multiple images taken from the same end face are stitched together to form a complete image of the end face, which is used for surveying the information of the entire end face.

[0050] In some embodiments, the underwater robot localization and surveying method based on multibeam sonar further includes:

[0051] Based on the underwater robot's location, control the underwater robot to cruise along a set trajectory and survey the internal conditions of the entire confined space.

[0052] In some embodiments, during directional navigation, the process includes:

[0053] Cruise trajectory planning is carried out based on the surveyed limited space outline and the equipment layout within the limited space, including the cables arranged on both sides of the cable well.

[0054] Based on the real-time positioning process, the underwater robot is positioned so that its positioning coordinates are consistent with the planned cruise trajectory, thereby enabling the underwater robot to navigate in a directional manner and complete the survey of the internal state of a confined space. Attached Figure Description

[0055] Figure 1 is a flowchart of the underwater robot localization and surveying method based on multibeam sonar in an embodiment of this application.

[0056] Figure 2 is a schematic diagram of the sonar coordinate system in an embodiment of this application;

[0057] Figure 3 is a schematic diagram of an underwater robot conducting surveys inside a cable well according to an embodiment of this application.

[0058] Figure 4 is a schematic diagram of the outline survey results of a cable well with two ear chambers in an embodiment of this application;

[0059] Figure 5 is a schematic diagram of the underwater robot's sonar coordinate system and the positional relationship of the underwater robot in a limited space under the deflection angle B in the embodiment of this application.

[0060] Figure 6 is a schematic diagram of the image stitching process of the cable well borehole resource exploration process in an embodiment of this application.

[0061] Figure 7 is a schematic diagram of directional cruise in an embodiment of this application;

[0062] Figure 8 is a schematic diagram of the internal structure of the six-beam ranging sonar in the embodiment of this application;

[0063] Figure 9 is a schematic diagram showing the positional relationship between the left front ranging sonar and the right front ranging sonar in the embodiments of this application. Detailed Implementation

[0064] Example 1

[0065] This application discloses an underwater robot localization and surveying method based on multibeam sonar, as shown in Figure 1, including:

[0066] Step S1: Establish the sonar coordinate system after the underwater robot carrying the multibeam sonar enters the confined space; the sonar coordinate system takes the end face of one of the ranging sonars in the multibeam sonar as the origin, and marks the coordinate values ​​of each axis by measuring the distance from each wall end face of the confined space by the ranging sonar that is aligned with the orientation of each axis of the coordinate system.

[0067] Step S2: The underwater robot scans and measures the contour of the limited space using a multibeam sonar, and uses the coordinate values ​​of the sonar coordinate system to represent the survey contour of the limited space.

[0068] Step S3: In the limited space of the surveyed contour, the underwater robot is located in real time according to the coordinate values ​​of the sonar coordinate system determined in real time by the multibeam sonar, and the positioning coordinate values ​​are obtained.

[0069] Step S4: When the underwater robot uses the captured images to conduct a limited space end face survey, the images are calibrated by the real-time positioning coordinates of the captured image positions; the calibration information is used to stitch together images captured on the same end face to complete the survey of the entire end face information.

[0070] For example, the multibeam sonar is a six-beam ranging sonar mounted on the bottom of the underwater robot. After mounting, it forms five horizontal component ranging sonars parallel to the underwater robot body and one vertical component ranging sonar perpendicular to the underwater robot body.

[0071] Among them, the five horizontal component ranging sonars are the left front, right front, right, rear, and left ranging sonars; among them,

[0072] The left and right front ranging sonars are set on a plane parallel to the body of the underwater robot, facing the front of the underwater robot. The ranging positions of the left and right front ranging sonars are symmetrical to the front and rear central axes of the underwater robot, and are used to measure the distance from the underwater robot to the boundary of the confined space at their respective ranging positions.

[0073] When the finite space boundary on the front side of the underwater robot is defined as the front wall, the left front and right front ranging sonars measure the distance to the front wall of the finite space at their respective ranging azimuths.

[0074] The left, rear, and right ranging sonars are set on a plane parallel to the underwater robot body, facing the left, rear, and right sides of the underwater robot respectively, with ranging azimuths differing by 90 degrees; the left, rear, and right ranging sonars are used to measure the distance from the underwater robot to the boundary of the confined space at their respective ranging azimuths.

[0075] When the finite space boundary at the front of the underwater robot is defined as the front wall, the left, rear, and right ranging sonars measure the distance to the left, rear, and right walls of the finite space, respectively.

[0076] The vertical component ranging sonar is perpendicular to the underwater robot's body and faces the bottom of the confined space. It is used to measure the distance from the bottom of the underwater robot to the bottom of the confined space.

[0077] For example, in step S1, the established sonar coordinate system is a four-axis coordinate system, in which the measurement end face of the rear ranging sonar is the origin of the coordinate system, and the distance measurement axes of the left, rear, and right ranging sonars and the vertical component ranging sonar are used as the coordinate axes of the coordinate system.

[0078] In this context, the distance measurement axis of the ranging sonar will be the x-axis, and the distance measurement values ​​will be coordinates. With the distance measurement axis of the left ranging sonar as the positive y-axis, the distance measurement values ​​are on the coordinate system. With the distance measurement axis of the right ranging sonar as the negative y-axis, the distance measurement value is the coordinate... The distance measurement axis of the vertical component ranging sonar is taken as the z-axis, and the distance measurement value is the coordinate system. ;

[0079] The sonar coordinates of the underwater robot, marked by distance measurements from the rear, left, and right ranging sonars and the vertical component ranging sonar, are as follows: .

[0080] Figure 2 shows a schematic diagram of the sonar coordinate system in an embodiment of this application.

[0081] The four-axis sonar coordinate system in this embodiment is specifically designed for ranging in a limited space using multibeam sonar, for example, to adapt to the positioning of underwater robots surveying regular-shaped cable wells.

[0082] Figure 3 is a schematic diagram of the underwater robot's survey inside a cable well. Cable wells are typically rectangular or similar structures with a horizontal cross-section. The underwater robot, equipped with the six-beam ranging sonar of this embodiment, is positioned inside the cable well with its body parallel to the well's horizontal cross-section. It uses the rear, left, and right ranging sonars and the vertical component ranging sonar of the six-beam ranging sonar to measure the distances to the rear, left, and right walls and the bottom of the cable well, respectively, obtaining the sonar coordinate system coordinates. This allows for the marking of the underwater robot's position inside the cable well.

[0083] When using a sonar coordinate system for location marking, it is necessary to keep the ranging axis of the multibeam sonar perpendicular to the walls of each cable well. For underwater robots conducting surveys in typically horizontal cable wells, the process of establishing a sonar coordinate system includes:

[0084] 1) After the underwater robot enters the confined space, adjust the underwater robot's pitch attitude so that the underwater robot's pitch angle is the same as the tilt angle of the axis of the confined space, including the cable well; ensure that the rear, left, and right ranging sonars and the vertical component ranging sonar used for coordinate value marking are perpendicular to the sound wave reflecting wall of the confined space in the pitch direction.

[0085] 2) Use the left and right front ranging sonars to measure the distance to the front wall of the confined space in which the underwater robot is facing, and adjust the underwater robot's orientation and attitude accordingly; when the ranging values ​​of the left and right front ranging sonars... , When they are equal, the underwater robot is perpendicular to the front wall of the limited space directly opposite its front end in the dimensional direction;

[0086] 3) According to , When the values ​​are equal, the data returned by the underwater robot's attitude sensor marks the underwater robot's orientation and attitude at this time as the zero-point attitude.

[0087] 4) Keep the zero-point attitude unchanged, and control the underwater robot to move left and right and rise and fall up and down by feedback of ranging data from the rear, left and right ranging sonar and vertical component ranging sonar until the fluctuation amplitude of the ranging data from the rear, left and right ranging sonar and vertical component ranging sonar is less than the preset threshold (i.e. the ranging data is stable), so as to avoid other objects in the limited space from obstructing the ranging process.

[0088] 5) The sonar coordinate system coordinates of the underwater robot, marked by distance measurements from the stable rear, left, and right ranging sonars and the vertical component ranging sonar, are as follows: .

[0089] For example, the contour surveying process in step S2 includes:

[0090] 1) Determine the starting point for contour surveying; after establishing the sonar coordinate system, maintain the zero-point attitude and translate the underwater robot to the first end face of the confined space, so that the rear ranging sonar is close to this first end face, which serves as the starting position for contour surveying. Record the distance measurements of the rear, left, and right ranging sonars, where the distance measurement of the rear ranging sonar is the x-coordinate of the starting position for contour surveying. The distance measurements from the left and right ranging sonars are the positive and negative y-coordinates of the starting position of the contour survey, respectively. , ;

[0091] 2) Conduct contour survey; maintain the zero-point attitude, control the underwater robot to move forward along the positive x-axis of the sonar coordinate system, and record the distance measurement values ​​of the rear, left, and right ranging sonars until the underwater robot translates to the second end face opposite the first end face in a limited space;

[0092] 3) Establish contour curves; establish a plane rectangular coordinate system, where the origin is the starting position of the contour survey, the horizontal axis is the x-axis of the sonar coordinate system, and the positive and negative half-axis of the vertical axis are the positive and negative y-axis of the sonar coordinate system; mark the distance measurements of the left and right ranging sonars in the plane rectangular coordinate system to form the boundary curves of the left and right contours of the finite space formed by the distance measurements of the left and right ranging sonars from the first end face to the second end face; on the boundary curves of the left and right contours, superimpose the first end face and the second end face to complete the survey of the finite space contour.

[0093] When surveying the outline of a cable well, the first and second end faces are the cable entry and exit faces of the cable well, both of which are planes. During the survey, the boundary curves of the surveyed left and right outlines are superimposed with the straight lines of the first and second end faces to form the outline of the cable well.

[0094] Figure 4 shows a schematic diagram of the outline survey results of a cable well with two side chambers.

[0095] For example, step S3 includes:

[0096] 1) Within the limited space of the surveyed contour, the coordinates of the underwater robot in the sonar coordinate system are determined in real time based on the ranging results of the multibeam sonar. ;

[0097] 2) Measure the deflection angle B of the underwater robot relative to the zero-point attitude in terms of orientation during operation;

[0098] The deflection angle B is calculated using trigonometric functions based on the ranging values ​​of the left and right front ranging sonars to the front wall of the confined space, combined with the ranging azimuth of the left or right front ranging sonar and the angle A between the front and rear central axis.

[0099] When the underwater robot deflects to the right relative to its zero-point attitude, the trigonometric function relationship satisfies:

[0100] ;

[0101] ;

[0102] When the underwater robot deflects to the left relative to its zero-point attitude, the trigonometric function relationship satisfies:

[0103] ;

[0104] .

[0105] 3) Based on the deflection angle B and the coordinates in the sonar coordinate system To determine the position of the underwater robot within a confined space;

[0106] The underwater robot's position within a confined space satisfies:

[0107] Distance from the rear wall: ;

[0108] Distance from left wall: ;

[0109] Distance from the right wall: ;

[0110] Distance from bottom: ;

[0111] according to To achieve real-time positioning of underwater robots.

[0112] Figure 5 shows a schematic diagram of the sonar coordinate system of the underwater robot and the positional relationship of the underwater robot in a limited space under deflection angle B.

[0113] For example, step S4 includes:

[0114] 1) When surveying the end face in a confined space, mark the shooting position of the underwater robot for each captured image;

[0115] The shooting position is based on the sonar coordinate system coordinates at the time of shooting. The underwater robot's position within a limited space is obtained by combining the deflection angle of the shooting position. ;

[0116] 2) Calibration coordinates based on multiple images taken from the same end face Image stitching is performed; among which, The value range is from 1 to the total number of images captured on that end face;

[0117] During the stitching process, multiple images are used... Determine the field of view size for each image, through multiple images. , Determine the left-right relationships and overlaps between the images, using multiple images... Determine the vertical relationship between the images;

[0118] 3) Multiple images taken from the same end face are stitched together to form a complete image of the end face, which is used for surveying the information of the entire end face.

[0119] Figure 6 shows a schematic diagram of the image stitching process during the exploration of cable well borehole resources.

[0120] During the survey process, in order to determine the size of the wellbore in the image, this embodiment uses laser dot marking to determine the size of objects in the image, including:

[0121] Two parallel laser beams are emitted in parallel within the camera's field of view. The lasers illuminate the object being photographed and then reflect back into the camera to form an image. The distance between the two parallel laser beams is known. Therefore, there are two laser spots in the captured image. Since the actual distance between the two laser beams is known, and the pixel distance between the two laser spots in the image can be measured, the size of the object, including the well hole, in the captured image can be calculated by combining the ratio of the distance between the two pixels of the object to the pixel distance between the two laser spots in the image with the actual distance between the two laser beams.

[0122] The survey scheme of this embodiment, the underwater robot positioning and surveying method based on multibeam sonar, further includes:

[0123] Step S5: Based on the underwater robot's location, control the underwater robot to cruise along the set cruise trajectory to survey the state of the entire confined space.

[0124] During directional navigation, the following are included:

[0125] 1) Plan the cruise trajectory; Based on the outline of the limited space surveyed in step S2, and the equipment layout within the limited space, including the cables arranged on both sides of the cable well, the cruise trajectory is planned; The planned cruise trajectory includes the locations to be surveyed within the limited space.

[0126] 2) Position the underwater robot according to the real-time positioning process in step S3, control the positioning coordinates of the underwater robot to be consistent with the planned cruise trajectory, realize the directional cruise of the underwater robot, and complete the survey of the internal state of the limited space.

[0127] Figure 7 shows a schematic diagram of directional cruise.

[0128] In summary, the embodiments of this application can achieve the following effects:

[0129] 1. When an underwater robot moves within a confined space, the distance between the underwater robot and the boundary of the confined space is measured in real time by a multibeam sonar mounted on the underwater robot. Combined with the survey contour of the confined space, the position of the underwater robot in the confined space is located.

[0130] 2. During the underwater robot's survey of a confined space end face (such as cable well borehole resources), the shooting position (the position of the underwater robot) of each captured image is marked. Based on the image shooting position, the images of the same end face are stitched together to complete the survey of the entire end face information.

[0131] 3. Based on the outline of the surveyed confined space and the layout of the equipment within the confined space (such as cables laid out on both sides of a cable well), plan the cruise trajectory of the underwater robot. By controlling the positioning coordinates of the underwater robot to be consistent with the cruise trajectory, automatic cruise can be achieved, thus completing the survey of the internal state of the confined space.

[0132] Example 2

[0133] This embodiment discloses a method for locating and surveying an underwater robot in a cable well; wherein the cable well is a rectangular or square finite space; and the underwater robot is placed in the water in the cable well.

[0134] For example, an underwater robot can be a vector-distributed multi-thrust underwater robot. By controlling the multi-thrust of the underwater robot, the underwater robot can have a full-space motion capability of 6 degrees of freedom, including forward and backward movement, surfacing and diving, left and right translation, left and right turning, forward and backward pitching and left and right flipping. It can also achieve stable directional navigation and constant-depth navigation.

[0135] In some embodiments, the underwater robot is also equipped with a gyroscope, accelerometer, 9-axis attitude sensor, magnetometer, depth gauge, water leakage sensor, internal barometer or other functional sensors to measure information such as the underwater robot's attitude, depth position and sealing status.

[0136] In some embodiments, the underwater robot is also equipped with a camera system and a lighting assistance system required for underwater surveying;

[0137] The camera system includes four sets of cameras located on the bow, left and right sides of the midship, and bottom of the underwater robot; it conducts optical surveys of the pipe resources, cable layout, and the arrangement of other equipment within the cable well.

[0138] The lighting assistance system includes lights corresponding to four cameras to provide auxiliary illumination for the cameras' optical surveying. The brightness of the lights can be automatically adjusted according to the ambient light level to obtain clearer and more effective optical survey images.

[0139] In some embodiments, the underwater robot is also fixedly equipped with a six-beam ranging sonar.

[0140] The six-beam ranging sonar is fixed to the bottom of the underwater robot and is generally cylindrical in shape. As shown in Figure 8, the six-beam ranging sonar 811 includes a sonar housing 8111, a mounting plate 8112, a left front ranging sonar 8113, a right front ranging sonar 8114, a rear ranging sonar 8115, a left ranging sonar 8116, a right ranging sonar 8117, and a vertical component ranging sonar 8118. The coordinate system in the figure is the body coordinate system of the underwater robot. In the body coordinate system, the length direction of the underwater robot body is the X-axis direction, the width direction is the Y-axis direction, and the height direction is the Z-axis direction.

[0141] Among them, the sonar housing 8111 is a sealed housing, the mounting plate 8112 is fixed inside the sonar housing 8111 and is parallel to the XY plane of the body coordinate system, the left front ranging sonar 8113, the right front ranging sonar 8114, the rear ranging sonar 8115, the left ranging sonar 8116 and the right ranging sonar 8117 are all fixed on the mounting plate 8112, and the acoustic axes are all located on the XY plane;

[0142] The left front ranging sonar 8113 and the right front ranging sonar 8114 are fixed to the front end of the mounting plate 8112 and are symmetrically arranged on both sides of the XZ plane of the body coordinate system. The angle between the acoustic axis (the axis of the ranging direction) and the X axis is A.

[0143] The left ranging sonar 8116 and the right ranging sonar 8117 are symmetrically fixed on both sides of the mounting plate 8112, and the acoustic axes of the left ranging sonar 8116 and the right ranging sonar 8117 are perpendicular to the XZ plane of the body coordinate system.

[0144] The rear ranging sonar 8115 is fixed to the rear end of the mounting plate 8112 and located on the XZ plane of the body coordinate system;

[0145] The vertical component ranging sonar 8118 is fixed inside the sonar housing 8111 by a mounting plate 8112 or other components, and the vertical component ranging sonar 8118 is arranged perpendicular to the mounting plate 8112.

[0146] In some embodiments, to avoid potential signal interference between the left front ranging sonar 8113 and the right front ranging sonar 8114, as shown in Figure 9, the included angle A is greater than or equal to the horizontal beam angle of the left front ranging sonar 8113 and the right front ranging sonar 8114. This ensures that even when the included angle A is at its minimum, it is equal to the horizontal beam angle of the sonar, and that the two opposing beam edges of the left front ranging sonar 8113 and the right front ranging sonar 8114 are parallel, effectively avoiding signal interference and improving the reliability of the measurement data.

[0147] In some embodiments, a calibration laser is also installed on the underwater robot; the calibration laser is used to calibrate the size of the wellbore hole in the image; the calibration laser is fixed to the bow of the underwater robot and includes two laser emitters, the beam directions of the two laser emitters being consistent with the refraction direction of the camera located at the bow.

[0148] In some embodiments, the line connecting the two laser emitters is perpendicular to the XZ plane of the body coordinate system. The image captured by the camera at the bow includes light spots reflected from the object illuminated by the two laser emitters. Since the actual distance between the two laser beams emitted by the two laser emitters is known, and the pixel distance between the two laser light spots in the image can be measured, the size of the object, including the wellhead hole, in the captured image can be calculated by combining the ratio of the distance between the two pixels of the measured object to the pixel distance between the two laser light spots in the image with the actual distance between the two laser beams.

[0149] In some embodiments, the underwater robot may also be equipped with a multibeam imaging sonar; the multibeam imaging sonar is fixed to the bow of the underwater robot and can achieve three-dimensional imaging of the internal condition of the cable well by using multiple beams, thereby obtaining richer and more comprehensive survey information.

[0150] The positioning and surveying method based on multibeam sonar used in this embodiment for underwater robots to perform tasks in cable wells, and the effects that can be achieved, are the same as in Embodiment 1.

Claims

1. A method for underwater robot localization and surveying based on multibeam sonar, comprising: Establish a sonar coordinate system after the underwater robot equipped with a multibeam sonar enters a confined space; the sonar coordinate system takes the end face of one of the ranging sonars in the multibeam sonar as the origin, and marks the coordinate values ​​of each axis by the distances from the end faces of each wall in the confined space measured by the ranging sonar with the same orientation as each axis of the coordinate system. The underwater robot scans and measures the contours of a limited space using multibeam sonar, and uses the coordinate values ​​of the sonar coordinate system to represent the survey contours of the limited space. Within the limited space of the surveyed contour, the underwater robot is located in real time based on the coordinate values ​​of the sonar coordinate system determined in real time by the multibeam sonar, and the positioning coordinate values ​​are obtained. When an underwater robot uses captured images to survey a confined space, the images are calibrated using real-time positioning coordinates. The calibration information is then used to stitch together images captured on the same end face to complete the survey of the entire end face.

2. The multi-beam sonar based underwater robotic positioning and surveying method of claim 1, wherein, The multibeam sonar is a six-beam ranging sonar mounted on the bottom of the underwater robot. After mounting, it forms five horizontal component ranging sonars parallel to the underwater robot body and one vertical component ranging sonar perpendicular to the underwater robot body. Among them, the five horizontal component ranging sonars are the left front, right front, right, rear, and left ranging sonars; among them, The left and right front ranging sonars are set on a plane parallel to the body of the underwater robot, facing the front of the underwater robot. The ranging positions of the left and right front ranging sonars are symmetrical to the front and rear central axes of the underwater robot, and are used to measure the distance from the underwater robot to the boundary of the confined space at their respective ranging positions. The left, rear, and right ranging sonars are set on a plane parallel to the underwater robot body, facing the left, rear, and right sides of the underwater robot respectively, with ranging azimuths differing by 90 degrees; the left, rear, and right ranging sonars are used to measure the distance from the underwater robot to the boundary of the confined space at their respective ranging azimuths. The vertical component ranging sonar is perpendicular to the underwater robot's body and faces the bottom of the confined space. It is used to measure the distance from the bottom of the underwater robot to the bottom of the confined space.

3. The multi-beam sonar based underwater robotic positioning and surveying method of claim 2, wherein, The established sonar coordinate system is a four-axis coordinate system. The measurement end face of the rear ranging sonar is the origin of the coordinate system, and the distance measurement axes of the left, rear, right ranging sonar and the vertical component ranging sonar are used as the coordinate axes of the coordinate system. wherein the distance measurement axis of the post-sonar is the x-axis and the distance measurement value is the coordinate ; the distance measurement axis of the left ranging sonar as the positive y-axis, and the distance measurement value as the coordinate ; the distance measurement axis of the right ranging sonar as the negative y-axis, and the distance measurement value as the coordinate ; the distance measurement axis of the vertical component measuring sonar is the z axis, and the distance measurement value is the coordinate ； The coordinates of the underwater robot in the sonar coordinate system marked by the distance measurement values of the rear, left, and right distance measuring sonars and the vertical component distance measuring sonar are 。 4. The multi-beam sonar based underwater robotic positioning and surveying method of claim 3, wherein, The process of establishing a sonar coordinate system includes: After the underwater robot enters the confined space, adjust the underwater robot's pitch attitude so that the underwater robot's pitch angle is the same as the axis tilt angle of the confined space, including the cable well, to ensure that the rear, left, and right ranging sonars and the vertical component ranging sonar used for coordinate value marking are perpendicular to the sound wave reflecting wall of the confined space in the pitch direction. The left front and right front distance measuring sonars are used to measure the distance value of the underwater robot towards the limited space front wall, and the orientation and posture of the underwater robot is adjusted; when the distance measuring value of the left front and right front distance measuring sonars is less than a preset value, the underwater robot is controlled to stop and the left front and right front distance measuring sonars are controlled to stop working 、 When they are equal, the underwater robot is perpendicular to the front wall end face of the limited space directly opposite its front end in the dimensional direction; According to 、 When the values ​​are equal, the data returned by the underwater robot's attitude sensor marks the underwater robot's orientation and attitude at this time as the zero-point attitude. Maintaining the zero-point attitude, the underwater robot is controlled to move left and right and rise and fall up and down by feedback from the ranging data of the rear, left and right ranging sonar and the vertical component ranging sonar until the fluctuation amplitude of the ranging data of the rear, left and right ranging sonar and the vertical component ranging sonar is less than the preset threshold, so as to avoid other objects in the limited space from obstructing the ranging process. The coordinates of the underwater robot's sonar coordinate system marked by the distance measurement values of the stable rear, left, right distance measuring sonar and the vertical component distance measuring sonar are 。 5. The multi-beam sonar based underwater robotic positioning and surveying method of claim 4, wherein, The process of conducting a contour survey includes: After the sonar coordinate system is established, the underwater robot is moved to the first end face of the limited space in a zero-point posture, the rear ranging sonar is made close to the first end face as a starting position of the profile survey, and the distance measurement values of the rear, left and right ranging sonars are recorded, wherein the distance measurement value of the rear ranging sonar is the x coordinate of the starting position of the profile survey , the distance measurement values of the left and right distance sounders are the positive and negative y coordinates of the profile survey starting position 、 ； Maintain the zero-point attitude, control the underwater robot to move forward along the positive x-axis of the sonar coordinate system, and record the distance measurements of the rear, left, and right ranging sonars until the underwater robot translates to the second end face opposite the first end face in a limited space; Establish a Cartesian coordinate system, where the origin is the starting position of the contour survey, the horizontal axis is the x-axis of the sonar coordinate system, and the positive and negative half-axis of the vertical axis are the positive and negative y-axis of the sonar coordinate system. Mark the distance measurements of the left and right ranging sonars in the Cartesian coordinate system to form the boundary curves of the left and right contours of the finite space formed by the distance measurements of the left and right ranging sonars from the first end face to the second end face. Based on the boundary curves of the left and right contours, superimpose the first end face and the second end face to complete the survey of the finite space contour.

6. The multi-beam sonar based underwater robotic positioning and surveying method of claim 5, wherein, Within the limited space of the surveyed contour, the underwater robot is positioned in real time based on the coordinate values ​​of the sonar coordinate system determined in real time by multibeam sonar, resulting in positioning coordinate values, including: In the limited space of the survey profile, the coordinates of the underwater robot in the sonar coordinate system are determined in real time according to the ranging results of the multi-beam sonar ； Measure the deflection angle B of the underwater robot relative to the zero-point attitude in terms of orientation; According to the deflection angle B and the coordinates in the sonar coordinate system Determine the position of the underwater robot within a confined space; the position of the underwater robot within the confined space satisfies: Distance from back wall: ； Distance to left wall: ； Distance to right wall: ； Distance from bottom: ； According to To achieve real-time positioning of underwater robots.

7. The multi-beam sonar based underwater robotic positioning and surveying method of claim 6, wherein, The deflection angle B is calculated using trigonometric functions based on the ranging values ​​of the left front and right front ranging sonars to the front wall of the confined space, combined with the ranging azimuth of the left front or right front ranging sonar and the angle A between the front and rear central axis. When the underwater robot deflects to the right relative to its zero-point attitude, the trigonometric function relationship satisfies: ； ； When the underwater robot deflects to the left relative to its zero-point attitude, the trigonometric function relationship satisfies: ； 。 8. The multi-beam sonar based underwater robotic positioning and surveying method of claim 6, wherein, When the underwater robot performs a limited-space end-face survey using captured images, the images are calibrated using real-time positioning coordinates of the captured image locations; the calibration information is then used to stitch together images captured from the same end-face to complete the survey of the entire end-face information, including: In the limited space end face surveying, the shooting position of the underwater robot is marked for each image; the shooting position is the coordinate of the sonar coordinate system at the time of shooting , in combination with the deflection angle of the shooting position, to obtain the position of the underwater robot in the limited space ； Calibration coordinates of multiple images taken with the same end face performing image stitching, wherein i ranges from 1 to the total number of the end face shot images; in the process of stitching, the image stitching is performed by using the image stitching method of the present application determining a field of view size for each image, by a plurality of images ， determining the left-right relationship between the images and the overlapping relationship of the left and right, by a plurality of images Determine the vertical relationship between the images; Multiple images taken from the same end face are stitched together to form a complete image of the end face, which is used for surveying the information of the entire end face.

9. The underwater robot localization and surveying method based on multibeam sonar according to claim 6, the method further includes: Based on the underwater robot's location, control the underwater robot to cruise along a set trajectory and survey the internal conditions of the entire confined space.

10. The multi-beam sonar based underwater robotic positioning and surveying method of claim 9, wherein, The directional cruise process includes: Cruise trajectory planning is carried out based on the surveyed limited space outline and the equipment layout within the limited space, including the cables arranged on both sides of the cable well. Based on the real-time positioning process, the underwater robot is positioned so that its positioning coordinates are consistent with the planned cruise trajectory, thereby enabling the underwater robot to navigate in a directional manner and complete the survey of the internal state of a confined space.

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