An autonomous hole-passing method for an underwater submersible

Abstract

The present invention provides an autonomous through-hole method for an underwater submersible, which includes a main body of the submersible device and sensors and ranging sonars arranged on the main body of the submersible device. The sensors and the ranging sonars are signal-connected to the main body of the submersible device. The sensors are used to obtain the attitude data of the main body of the submersible device. The ranging sonar is provided with a first ranging sonar and a second ranging sonar. The autonomous through-hole method for an underwater submersible provided by the present invention uses a data fusion algorithm to adjust the attitude of the ROV so that its sailing direction is almost consistent with the axis of the narrow channel (through-hole) ahead, and by adjusting the attitude and heading in real time, the main body of the ROV submersible device can be maintained near the central axis of the narrow channel (through-hole) during the driving process, ensuring that the ROV can smoothly pass through the narrow channel (through-hole) and realizing the function of the main body of the underwater operation submersible device to autonomously pass through the hole with real-time attitude adjustment.

Description

Technical Field

[0001] The present invention relates to the field of underwater submersible equipment, and particularly to an autonomous hole-passing method for an underwater submersible equipment. Background Art

[0002] As is well known, the hole-passing technology of remotely operated underwater vehicles (ROVs) is one of the key technologies in the fields of underwater engineering, ocean exploration, underwater archaeology, etc. Currently, when underwater diving equipment passes through an underwater narrow space, that is, a hole, it mainly relies on remote manual operation modes such as remote control and remote instructions. Since the underwater environment, especially the internal structure of the narrow space, is relatively complex, it is difficult to directly obtain the equipment state and environmental parameters. During construction, it depends on various sensors carried by the equipment, such as sonar positioning, positioning systems (GPS), etc., and is also easily affected by factors such as signal interference or signal interruption. If the operator observes the driving situation of the equipment and limited image information, and then manually adjusts the equipment's traveling speed and direction, the accuracy of controlling the jetting action is not high. If manual operation is carried out for a long time, situations such as operator fatigue and inattention will occur, resulting in a series of unexpected situations that affect construction, such as equipment failures. Therefore, factors such as low visibility, high pressure, temperature changes, and water flow in the underwater environment pose challenges to the hole-passing technology of underwater equipment. Coupled with the fact that the propagation speed and attenuation characteristics of underwater sound waves in water are different from those in air, which affects the performance of sonar, a method can be provided to combine the feedback data of sonar and the attitude data of IMU, and use a data fusion algorithm to adjust the attitude of the ROV so that its sailing direction is consistent with the axis of the hole. By adjusting the attitude and heading in real time, the entire ROV can be maintained near the central axis of the hole during the driving process, and a method for the ROV to autonomously pass through the hole by adjusting the attitude in real time. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a method that combines the feedback data of sonar and the attitude data of sensors, and uses a data fusion algorithm to adjust the attitude, so as to realize the real-time adjustment of the attitude and heading of an underwater submersible and perform autonomous hole-passing.

[0004] To achieve the purpose of the present invention, the present invention provides an autonomous hole-passing method for an underwater submersible, including a main body of the submersible equipment and sensors and ranging sonars arranged on the main body of the submersible equipment. The sensors and the ranging sonars are signal-connected to the main body of the submersible equipment. The sensors are used to obtain the attitude data of the main body of the submersible equipment. The ranging sonar is provided with a first ranging sonar and a second ranging sonar. The first ranging sonar is used for short-distance measurement, and the second ranging sonar is used for long-distance measurement. The method specifically includes the following steps:

[0005] S1. Enable the ranging sonar to detect the surrounding environment;

[0006] S2. Decelerate or stop the forward movement of the main body of the submersible device according to the minimum distance value obtained by the second ranging sonar;

[0007] S3. Switch the main body of the submersible device to enter the attitude adjustment mode for autonomous hole passing;

[0008] S4. Detect the distance between the sonar and the surrounding environment, and judge whether the main body of the submersible device has passed through the hole;

[0009] S5. Adjust the driving mode of the main body of the submersible device to end the hole passing process;

[0010] The first ranging sonar is a front sonar, and there is at least one set of front sonars;

[0011] The second ranging sonar is a side sonar, and there are at least four sets of side sonars;

[0012] When performing step S3, combine the data of the sensors and the ranging sonars, and adjust the attitude and heading of the main body of the submersible device according to the data fusion algorithm.

[0013] Preferably, the front sonar is arranged on the central axis of the front end of the ROV, and can be exposed or hidden inside the anti-collision bar. The central plane of the sonar beam is basically parallel to the ROV body frame. After the load of the ROV changes, it is necessary to ensure that the maximum deviation range of the angle with the ROV body frame is 3° - 5°.

[0014] Preferably, the side sonars are arranged at the four corner positions of the ROV main body and are symmetrically arranged left and right. The sonars form a 30° angle with the ROV driving direction, and the maximum deviation range of the angle is 3° - 5°.

[0015] Preferably, the sensor is an attitude sensor, and the attitude sensor is arranged at the central position on the upper surface of the ROV main body. When installed, it is parallel to the horizontal plane, and the x-axis direction is consistent with the forward direction of the ROV.

[0016] Preferably, step S3 includes the following sub-steps:

[0017] S31. Initialize the state vector of the unscented Kalman filter, including position and speed;

[0018] S32. Define a non-linear observation model, and map the state vector to the observable sonar distance and the attitude data of the attitude sensor;

[0019] S33. According to the mean and covariance matrix of the state vector, select a set of σ points through the transformation of the unscented Kalman filter, propagate each σ point through the non-linear state transition model, obtain the predicted σ points, and calculate the mean and covariance of the predicted σ points as the predicted state estimate and its uncertainty;

[0020] S34. Use the distance data from the sonar and the attitude data from the IMU, apply the observation model to the predicted sigma points, obtain the predicted observation values, calculate the mean and covariance of the observation values, and use them for the update step;

[0021] S35. Use the covariance of the predicted observation values and the observation noise covariance to calculate the Kalman gain, and repeat the prediction and update steps at each time step to achieve continuous estimation of the ROV's spatial position;

[0022] S36. Detect the distance between the sonar and the surrounding environment space. When there is no return result from the front sonar and the results of both sets of side sonars are less than 0.5 m, it is considered that there is a narrow passage ahead, enter the attitude adjustment mode, and prepare to pass through the hole;

[0023] S37. Customize the size of the area through which the ROV can safely pass according to the cross-sectional area of the ROV fuselage, and then combine the installation angles of the side sonars and the set safe passage area to calculate the minimum distance measurement result of the four sets of side sonars when the ROV is allowed to safely pass through this section;

[0024] S38. According to the position and speed output in step S36, first reduce the forward speed of the ROV or even stop moving forward, and then adjust the attitude of the ROV so that the distance values D measured by the four sets of side sonars are not less than Dm, and start passing through the hole. During the process of passing through the hole, repeat this step and adjust the attitude of the ROV in real time to keep the distance value D not less than Dm;

[0025] S39. Detect the distance between the sonar and the surrounding environment space. When there is no return result from the front sonar and the result of one or more side sonars is greater than or equal to 0.5 m, it is considered that the narrow passage has been passed through and the ROV has entered an open environment, and the ROV enters the normal driving mode to end the process of passing through the hole.

[0026] Preferably, step S1 includes the following sub-steps:

[0027] S11. According to the distance values returned by the first ranging sonar and the second ranging sonar, judge whether there are obstacles or narrow passages in the environment in the forward direction of the ROV body;

[0028] S12. When driving normally in an open space, when there is no return result from the front sonar and the return results of the side sonars are all greater than or equal to 0.5 m, it is considered that the front can continue to pass;

[0029] S13. When driving normally in an open space, when there is a return result from the front sonar, it is considered that there is an obstacle ahead. At this time, make corresponding obstacle avoidance adjustments according to the results measured by each sonar;

[0030] S14. Under normal driving in an open space, when there is no return result from the forward sonar and when the return result of one or more side sonars is less than 0.5 m, it is considered that there is a narrow channel ahead, and step S2 is entered.

[0031] Preferably, in sub-step S32, when obtaining the attitude data returned by the attitude sensor, the unscented Kalman filter first defines a non-linear state equation and an observation model for estimating the current attitude, tilt angle and relative motion trend of the main body of the underwater submersible device.

[0032] Preferably, in sub-step S37, the set safe passing area is set according to the cross-sectional area of the fuselage and the minimum cross-sectional area of the narrow channel.

[0033] Preferably, in sub-step S33, the predicted σ points are the sampling points sigma.

[0034] The beneficial effects of the present invention are as follows: The present invention provides an autonomous hole-passing method for an underwater submersible. By setting sensors and ranging sonars on the main body of the submersible device, the sensors are used to obtain the attitude data of the main body of the submersible device. The ranging sonars include a first ranging sonar and a second ranging sonar. The first ranging sonar is used for short-distance measurement, and the second ranging sonar is used for long-distance measurement. The feedback data of the sonars and the attitude data of the attitude sensor IMU are combined, and a data fusion algorithm is used to adjust the attitude of the ROV so that its navigation direction is almost the same as the axis of the narrow channel (hole-passing) ahead. And by adjusting the attitude and heading in real time, the main body of the ROV submersible device can be maintained near the central axis of the narrow channel (hole-passing) during driving, ensuring that the ROV can smoothly pass through the narrow channel (hole-passing), and realizing the function of real-time adjusting the attitude and autonomous hole-passing of the main body of the underwater operation submersible device. Description of the Drawings

[0035] More specifically illustrated by the preferred embodiments of the present invention shown in the drawings, the above and other objects, features and advantages of the present invention will become clearer. The same reference numerals indicate the same parts in all the drawings, and the drawings are not deliberately drawn to scale in actual size, with the emphasis on showing the gist of the present invention.

[0036] Figure 1 It is a schematic diagram of the equipment for an autonomous hole-passing method for an underwater submersible of the present invention;

[0037] Figure 2 It is a schematic diagram of the basic process for an autonomous hole-passing method for an underwater submersible of the present invention;

[0038] Figure 3 It is a schematic diagram of a specific embodiment of an autonomous hole-passing method for an underwater submersible of the present invention;

[0039] Figure 4 Schematic diagram of a preferred embodiment of an autonomous hole-passing method for an underwater submersible according to the present invention.

[0040] In the figure: 1. Main body of the submersible device; 2. Sensor; 3. Front sonar; 4-7. Side sonars. Detailed implementation manners

[0041] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings.

[0042] It should be noted that when an element is considered to be "connected" to another element, it can be directly connected to the other element and integrated therewith, or there may be an intermediate element at the same time. The terms "installed", "one end", "the other end" and similar expressions used herein are only for the purpose of illustration.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this invention belongs. The terms used in the description of the present invention herein are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0044] As Figures 1-4 shown, the preferred embodiment of the present invention provides an autonomous hole-passing method for an underwater submersible, including a main body 1 of the submersible device and a sensor 2 and a ranging sonar disposed on the main body of the submersible device. The sensor 2 and the ranging sonar are signal-connected to the main body of the submersible device. The sensor 2 is used to obtain the attitude data of the main body of the submersible device. The ranging sonar is provided with a first ranging sonar and a second ranging sonar. The first ranging sonar is used for short-distance measurement, and the second ranging sonar is used for long-distance measurement. In this embodiment, the main body of the submersible device is also abbreviated as ROV. The ROV passing through a hole is to pass through a narrow channel, and specifically includes the following steps:

[0045] S1. Enable the ranging sonar to detect the surrounding environment;

[0046] S2. Decelerate or stop the forward movement of the main body of the submersible device according to the minimum distance value obtained by the second ranging sonar;

[0047] S3. Switch the main body of the submersible device to enter the attitude adjustment mode for autonomous hole-passing;

[0048] S4. Detect the distance between the sonar and the surrounding environment, and judge whether the main body of the submersible device has passed through the hole;

[0049] S5. Adjust the driving mode of the main body of the submersible device to end the hole-passing process;

[0050] The first ranging sonar is the front sonar 3, and there is at least one set of front sonar 3;

[0051] The second ranging sonar is the side sonar 4, and there are at least four sets of side sonars 4;

[0052] When performing step S3, the data of the sensor 2 and the ranging sonar are combined, and the attitude and heading of the main body 1 of the submersible device are adjusted according to the data fusion algorithm, so that the whole ROV can maintain near the central axis of the narrow channel (through hole) during driving, ensuring that the ROV can smoothly pass through the narrow channel (through hole), and realizing the function of the ROV for underwater operation to autonomously pass through the hole with real-time attitude adjustment.

[0053] Reference Figures 1-4 As shown, in a further preferred embodiment, the front sonar 3 is arranged on the central axis of the front end of the ROV, and can be exposed or hidden inside the anti-collision bar. The central plane of the sonar beam is basically parallel to the frame of the ROV body. After the load of the ROV changes, it is necessary to ensure that the maximum deviation range of the angle with the frame of the ROV body is 3° - 5°. Specifically, in this embodiment, the maximum deviation value of the angle with the frame of the ROV body is 5°.

[0054] Reference Figures 1-4 As shown, in a further preferred embodiment, the side sonars 4 are arranged at the four corner positions of the ROV main body and are arranged symmetrically left and right. The sonar forms an angle of 30° with the driving direction of the ROV, and the maximum deviation range of the angle is 3° - 5°. Specifically, in this embodiment, the maximum deviation value of the angle is 5°.

[0055] Reference Figures 1-4 As shown, in the preferred embodiment, the sensor 2 is an attitude sensor, and the attitude sensor 2 is arranged at the central position on the upper surface of the ROV main body. When installed, it is parallel to the horizontal plane, and the x-axis direction is consistent with the forward direction of the ROV.

[0056] Reference Figures 1-4 As shown, in the preferred embodiment, during the attitude adjustment stage, when the ROV determines that there is a narrow space ahead, the program will switch the ROV mode from the normal driving mode to the attitude adjustment mode to perform the attitude adjustment before passing through the hole;

[0057] Step S3 includes the following sub-steps:

[0058] S31. Initialize the state vector of the unscented Kalman filter (UKF), including position and velocity;

[0059] S32. Define a non - linear observation model to map the state vector to the observable sonar distance and the attitude data of the attitude sensor. Since the ROV motion is non - linear, when obtaining the attitude data returned by the IMU, the UKF (Unscented Kalman Filter) first defines a non - linear state equation and an observation model to estimate the current attitude, tilt angle, relative motion trend, etc. of the ROV;

[0060] S33. According to the mean and covariance matrix of the state vector, select a set of σ - points through the transformation of the Unscented Kalman Filter, propagate each σ - point through the non - linear state transition model to obtain the predicted σ - points, and calculate the mean and covariance of the predicted σ - points as the predicted state estimate and its uncertainty;

[0061] S34. Use the distance data of the sonar and the attitude data of the IMU, apply the observation model to the predicted σ - points to obtain the predicted observation values, and calculate the mean and covariance of the observation values for the update step;

[0062] S35. Utilize the covariance of the predicted observation values and the observation noise covariance to calculate the Kalman gain, and repeat the prediction and update steps at each time step to achieve continuous estimation of the ROV's spatial position;

[0063] S36. Detect the distance between the sonar and the surrounding environment space. When there is no return result from the front sonar 3 and the results of both sets of side - mounted sonars 4 are less than 0.5 m, it is considered that there is a narrow channel ahead, and enter the attitude adjustment mode to prepare for passing through the hole;

[0064] S37. Customize the size of the area where the ROV can safely pass according to the cross - sectional area of the ROV fuselage, and then combine the installation angle of the side - mounted sonar 4 and the set safe - passing area to calculate the minimum ranging result Dm of the four sets of side - mounted sonars 4 when the ROV can safely pass through the cross - section;

[0065] S38. According to the position and speed output in step S36, first reduce the forward speed of the ROV or even stop moving forward, and then adjust the attitude of the ROV so that the distance values D measured by the four sets of side - mounted sonars 4 are not less than Dm, and start passing through the hole. During the process of passing through the hole, repeat this step and adjust the attitude of the ROV in real - time to keep the distance value D not less than Dm; collect the distance data of the surrounding space through the sonar matrix, calculate the four target distances through the feedback data of the side - mounted sonar 4 matrix, and then combine the installation angle and installation position to calculate a passage space (with an approximately rectangular cross - section) in front of the ROV that is nearly parallel to the ROV body frame (the included angle ≤ 5°). Adjust the attitude until this passage cross - section is slightly wider than the cross - section of the ROV, and it is considered that the current state can move forward safely and start passing through the narrow channel (passing through the hole);

[0066] S39. Detect the distance between the detection sonar and the surrounding environment space. When there is no return result from the front sonar 3 and the result of one or more side sonars is greater than or equal to 0.5 m, it is considered that the narrow channel has been passed and the ROV has entered the open environment, and the ROV enters the normal driving mode to end the process of passing through the hole.

[0067] The embodiment of the present invention provides a more efficient solution. By collecting the data of the sonar matrix and the attitude data of the attitude measurement unit (IMU), including acceleration, angular velocity and possible magnetic field data, data fusion is carried out.

[0068] Reference Figures 1-4 As shown, in the preferred embodiment, step S1 includes the following sub-steps:

[0069] S11. According to the distance values returned by the first ranging sonar and the second ranging sonar, judge whether there are obstacles or narrow channels in the environment in the forward direction of the ROV body.

[0070] S12. When driving normally in an open space, if there is no return result from the front sonar 3 and the return results of the side sonars 4 are all greater than or equal to 0.5 m, it is considered that the front can continue to pass.

[0071] S13. When driving normally in an open space, if there is a return result from the front sonar 3, it is considered that there is an obstacle in the front. At this time, according to the results measured by each sonar, corresponding obstacle avoidance adjustments are made.

[0072] S14. When driving normally in an open space, if there is no return result from the front sonar 3 and when the return result of one or more of the side sonars 4 is less than 0.5 m, it is considered that there is a narrow channel in the front, and step S2 is entered.

[0073] The present invention provides a more efficient solution. By collecting the data of the sonar matrix and the attitude data of the attitude measurement unit (IMU), including acceleration, angular velocity and possible magnetic field data, data fusion is carried out. Before fusion, it is necessary to filter the sonar data to remove noise and multipath effects, and calibrate the IMU data to eliminate sensor biases and errors. First, use the sonar data for preliminary positioning to determine the relative position of the ROV and the surrounding environment, and judge whether there is a narrow channel in the front.

[0074] Reference Figures 1-4 As shown, in a further preferred embodiment, in sub-step S32, when obtaining the attitude data returned by the attitude sensor, the unscented Kalman filter first defines the nonlinear state equation and the observation model for estimating the current attitude, tilt angle and relative motion trend of the main body of the underwater submersible equipment.

[0075] Reference Figures 1-4, in a preferred embodiment, in the sub-step S37, the set safe passage area is set according to the cross-sectional area of the fuselage and the minimum cross-sectional area of the narrow passage.

[0076] Reference Figures 1-4 , in a preferred embodiment, in sub-step S33, the predicted σ point is the sampling point sigma.

[0077] The present invention also provides an embodiment of sub-step S37:

[0078] Specifically, referring to Figure 4 , the cross-sectional area is represented by length and width, with the unit of centimeter. Assume the cross-sectional area of the ROV fuselage is (L, W) (unit: centimeter), and then define the size of the area where the ROV can safely pass as (L + 2, W + 2). Since the installation angle is 30°, according to sin(30°)=Δd / Dm, and Δd =((L + 2)-L) / 2, where Δd is a passing distance reserved according to the length and width of the device cross-section. According to the formula calculation, the minimum value Dm of the ranging result of the side-mounted sonar when the ROV can safely pass through the narrow passage can be obtained.

[0079] Embodiment 1:

[0080] Specifically, when the cross-sectional area of the ROV fuselage is (49.9, 29.6), the size of the area where the ROV can safely pass is (51.9, 31.6); substituting into the formula sin(30)=Δd / Dm, Δd=(49.9 + 2)-49.9) / 2 for calculation, Δd = 1 is obtained, and the minimum value Dm of the ranging result is Dm = 2.

[0081] Embodiment 2:

[0082] When the cross-sectional area of the ROV fuselage is (38, 30), the size of the area where the ROV can safely pass is (40, 32); substituting into the formula sin(30)=Δd / Dm, Δd=((38 + 2)-L) / 2 for calculation, Δd = 1 is obtained, and the minimum value Dm of the ranging result is Dm = 2.

[0083] Embodiment 3:

[0084] When the cross-sectional area of the ROV fuselage is (45, 40), the size of the area where the ROV can safely pass is (47, 42); substituting into the formula sin(30)=Δd / Dm, Δd =((L + 2)-L) / 2 for calculation, Δd = 1 is obtained, and the minimum value Dm of the ranging result is Dm = 2.

[0085] Through the above three embodiments, it can be obtained that when the ROV main body of various different sizes passes through the narrow passage, if the length-width ratio of the current environmental space exceeds the length-width of the cross-section of the device main body by 1 cm, it is considered that the narrow passage can be safely passed.

[0086] The beneficial effects of the present invention are as follows: The present invention provides an autonomous through-hole method for an underwater submersible. By providing sensors and ranging sonars on the main body of the submersible device, the sensors are used to obtain the attitude data of the main body of the submersible device. The ranging sonars include a first ranging sonar and a second ranging sonar. The first ranging sonar is used for short-distance measurement, and the second ranging sonar is used for long-distance measurement. The feedback data of the sonars and the attitude data of the attitude sensor IMU are combined, and a data fusion algorithm is used to adjust the attitude of the ROV so that its navigation direction is almost consistent with the axis of the narrow channel (through-hole) ahead. Moreover, by adjusting the attitude and heading in real time, the main body of the ROV submersible device can be maintained near the central axis of the narrow channel (through-hole) during the driving process, ensuring that the ROV can smoothly pass through the narrow channel (through-hole), and realizing the function of the main body of the underwater operation submersible device to autonomously pass through the hole by real-time attitude adjustment.

[0087] In this application, unless otherwise clearly specified and limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "below" and "beneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0088] In the description of this specification, the description with reference to terms such as "preferred embodiment", "another embodiment", "other embodiments" or "specific examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0089] The above embodiments only represent several implementation manners of the invention, and the description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the inventive concept, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent should be subject to the appended claims.

Claims

1. An autonomous through-hole method for an underwater submersible, comprising a main body of the submersible device and sensors and ranging sonars arranged on the main body of the submersible device, wherein the sensors and ranging sonars are signal-connected to the main body of the submersible device, the sensors are used to obtain the attitude data of the main body of the submersible device, the ranging sonars are provided with a first ranging sonar and a second ranging sonar, the first ranging sonar is used for short-distance measurement, and the second ranging sonar is used for long-distance measurement, characterized in that: Specifically, it includes the following steps: S1. Enable the ranging sonar to detect the surrounding environment; S2. Decelerate or stop the forward movement of the main body of the submersible device according to the minimum distance value obtained by the second ranging sonar; S3. Switch the main body of the submersible device to the attitude adjustment mode to pass through the hole autonomously; S4. Detect the distance between the sonar and the surrounding environment, and judge whether the main body of the submersible device has passed through the hole; S5. Adjust the driving mode of the main body of the submersible device to end the process of passing through the hole; The step S3 includes the following sub-steps: S37. Customize the size of a safely passable area for the ROV according to the cross-sectional area of the ROV fuselage. Then, combine the installation angle of the side-mounted sonar and the set safely passable area to calculate the minimum ranging result of the four sets of side-mounted sonars when the ROV is allowed to safely pass through this cross-section. Use length and width to represent the cross-sectional area, with the unit of centimeter. Set the cross-sectional area of the ROV fuselage as (L, W), with the unit of centimeter. Then define the size of the safely passable area for the ROV as (L + 2, W + 2). Since the installation angle is 30°, according to sin(30°)=Δd / Dm, and Δd =((L + 2)-L) / 2, where Δd is a passing distance reserved according to the length and width of the device cross-section. Through formula operation, the minimum value Dm of the ranging result of the side-mounted sonar when the ROV can safely pass through the narrow channel can be obtained; S38. Collect the distance data of the surrounding space through the sonar matrix. Calculate four target distances through the feedback data of the side-mounted sonar matrix, and then combine the installation angle and installation position to calculate a cross-section of the passing space parallel to the ROV body frame in front of the ROV. Adjust the attitude until the cross-section of this passing space is wider than the cross-section of the ROV, and it is considered that the current state can safely move forward through the hole; According to the position and speed output by step S36, first reduce the forward speed of the ROV or even stop moving forward, and then adjust the attitude of the ROV so that the distance values D measured by the four sets of side-mounted sonars are not less than Dm, and start passing through the hole. During the process of passing through the hole, repeat this step and adjust the attitude of the ROV in real time to keep the distance value D not less than Dm; S39. Detect the distance between the sonar and the surrounding environment space. When there is no return result from the front sonar and the result of one or more side-mounted sonars is greater than or equal to 0.5 m, it is considered that the narrow channel has been passed through and the ROV has entered the open environment, and the ROV enters the normal driving mode to end the process of passing through the hole.

2. The autonomous through-hole method for an underwater submersible according to claim 1, wherein The front sonar is set on the central axis at the front end of the ROV, and can be exposed or hidden inside the anti-collision bar. The central plane of the sonar beam is basically parallel to the ROV body frame. After the load of the ROV changes, the maximum deviation range of the included angle with the ROV body frame needs to be 3° - 5°.

3. The autonomous through-hole method for an underwater submersible according to claim 1, wherein, The side-mounted sonars are set at the four corner positions on the main body of the ROV and are arranged symmetrically left and right. The sonar forms a 30° angle with the ROV driving direction, and the maximum deviation range of the angle is 3° - 5°.

4. The autonomous through-hole method for an underwater submersible according to claim 1, wherein In the sub-step S33, the predicted σ point is the sampling point sigma.

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