Underwater device, distance observation method thereof, and computer readable storage medium

Abstract

The application discloses an underwater device, a distance-keeping observation method thereof and a computer readable storage medium. The underwater device is provided with at least a forward DVL. The method comprises the following steps: in response to a manual pitch angle adjustment instruction in an automatic distance-keeping observation mode, and during the pitch angle adjustment process, a preset vertical distance between the underwater device and a current observation surface of a measured object is maintained based on multi-beam slant distance data collected by the forward DVL; when the pitch angle of the underwater device exceeds a preset threshold value and the observation surface of the measured object is confirmed to be switched in combination with the multi-beam slant distance data, the spatial coordinates of a preset navigation path are converted according to the spatial posture of the observation surface after the switching, so that the underwater device continues to perform the automatic distance-keeping observation along the converted navigation path. The application can keep the distance-keeping uninterrupted when the pitch posture is manually adjusted, accurately identify the observation surface switching and adaptively adjust the navigation path, and ensure the continuous and smooth observation of the underwater device.

Description

Technical Field

[0001] This application relates to the field of marine observation technology, and in particular to an underwater device and its distance observation method, as well as a computer-readable storage medium. Background Technology

[0002] Existing underwater equipment, such as underwater robots, generally suffers from the following problems when performing fixed-distance observations of underwater structures: In automatic distance control mode, the system maintains a stable distance and a fixed pitch angle with the object being measured to achieve continuous and autonomous observation. Once the user manually intervenes in the pitch angle adjustment for temporary needs (such as avoiding obstructions or checking local details), the system will immediately exit the automatic operation mode completely, including the distance control function, and the user needs to re-establish a stable observation. In pure manual mode, it is difficult to maintain distance and pitch angle at the same time, and it is easy to collide with structures or lose the observation target. When the object being measured has multiple continuous planes with different orientations (such as the corner of a bridge pier or the corner of a ship hull), the traditional fixed navigation path cannot adapt to the new observation orientation after the pitch angle changes, resulting in discontinuous observation or missing data. Summary of the Invention

[0003] The main purpose of this application is to provide an underwater device and its fixed-distance observation method, as well as a computer-readable storage medium, which aims to solve the problems in the prior art where, during underwater device observation operations, the automatic mode of adjusting the pitch angle is prone to deviating from the fixed-distance control, the pure manual mode is difficult to balance distance and viewing angle, and the traditional fixed path cannot adapt to the changing viewing angle of multi-plane structures, which easily leads to collisions, target loss, and gaps in observation data.

[0004] To address the aforementioned technical problems, this application proposes a distance-fixed observation method for underwater equipment. The underwater equipment is equipped with at least a forward DVL (Directional Variation) system. The method includes: responding to a manual pitch angle adjustment command in automatic distance-fixed observation mode; during pitch angle adjustment, maintaining a preset vertical distance between the underwater equipment and the current observation surface of the object under test based on multibeam slant range data acquired by the forward DVL; when the pitch angle of the underwater equipment exceeds a preset threshold, and the observation surface of the object under test is confirmed to have switched based on the multibeam slant range data, performing a spatial coordinate transformation on a preset navigation path according to the spatial attitude of the switched observation surface, so that the underwater equipment continues to perform automatic distance-fixed observation along the transformed navigation path.

[0005] In one embodiment of this application, confirming that the observation surface of the object under test has switched includes: when the pitch angle of the underwater device exceeds a preset threshold, performing a synchronous lateral comparison and a time-series longitudinal comparison on the multibeam slant range data; when at least two sets of beams simultaneously exhibit lateral and longitudinal anomalies, confirming that the observation surface of the object under test has switched.

[0006] In one embodiment of this application, the simultaneous lateral comparison and temporal longitudinal comparison of the multi-beam slant range data includes: calculating the relative deviation between the slant range of each beam and its average value at the same time; when the relative deviation exceeds a preset lateral threshold, it is identified as a laterally abnormal beam; and determining the temporal change rate based on the slant range data of the same beam at different acquisition times; when the temporal change rate exceeds a preset longitudinal threshold, it is identified as a longitudinally abnormal beam.

[0007] In one embodiment of this application, when the observation surface of the object under test does not change, maintaining a preset vertical distance between the underwater device and the current observation surface of the object under test based on the multibeam slant range data acquired by the forward DVL includes: fitting the multibeam slant range data to obtain the plane equation of the current observation surface; calculating the actual vertical distance from the center of the underwater device to the current observation surface based on the plane equation; and adjusting the position of the underwater device in real time based on the difference between the actual vertical distance and the preset vertical distance to maintain the preset vertical distance unchanged.

[0008] In one embodiment of this application, when in a transitional state of observation surface switching, maintaining a preset vertical distance between the underwater device and the object under test based on the multi-beam slant range data acquired by the forward DVL includes: constructing a temporary reference plane based on effective beam slant range data and historical attitude normal vectors; calculating the actual vertical distance from the center of the underwater device to the temporary reference plane based on the temporary reference plane; and adjusting the position of the underwater device in real time based on the difference between the actual vertical distance and the preset vertical distance to maintain the preset vertical distance unchanged; wherein, the effective beam slant range data is the beam slant range data projected onto the observation surface after switching, and the historical attitude normal vector is the attitude normal vector corresponding to the original observation surface retained before the observation surface switching.

[0009] In one embodiment of this application, before performing spatial coordinate transformation on the preset navigation path based on the spatial attitude of the switched observation surface, the method further includes: correcting the pitch attitude of the underwater device based on the multibeam slant range data so that the underwater device faces the switched observation surface; and using the angle formed by the underwater device relative to the horizontal reference attitude as the final pitch angle.

[0010] In one embodiment of this application, the step of transforming the spatial coordinates of the preset navigation path according to the spatial attitude of the observation surface after switching includes: constructing a rotation matrix based on the final pitch angle; performing a spatial rotation transformation on the coordinates in the preset navigation path based on the rotation matrix to obtain the transformed navigation path; wherein the transformed navigation path at least retains some of the operating parameters of the preset navigation path unchanged.

[0011] In one embodiment of this application, the step of enabling the underwater device to continue performing automatic distance observation along the switched navigation path includes: fitting the multibeam slant range data to obtain the plane equation of the switched observation surface; calculating the actual vertical distance from the center of the underwater device to the switched observation surface based on the plane equation; and adjusting the position of the underwater device in real time based on the difference between the actual vertical distance and the preset vertical distance to maintain the preset vertical distance unchanged.

[0012] To address the aforementioned technical problems, this application also proposes an underwater device, comprising: a memory, a processor, and a control program for the underwater device stored in the memory and executable on the processor, wherein the control program is configured to implement the steps of the distance observation method for the underwater device as described above.

[0013] To address the aforementioned technical problems, this application also provides a computer-readable storage medium storing a control program for an underwater device. When executed by a processor, the control program for the underwater device implements the steps of the distance observation method for the underwater device as described above.

[0014] This application provides an underwater device and its distance-fixed observation method, as well as a computer-readable storage medium. By responding to manual pitch angle adjustment commands in automatic distance-fixed observation mode, and relying on slant range data collected by forward multibeam sonar to maintain a preset distance between the device and the observation surface in real time, and completing the spatial coordinate transformation of the navigation path after the pitch angle reaches the standard and the observation surface is confirmed to be switched, this technical means can flexibly adjust the observation pitch angle of the underwater device while maintaining the normal operation of the distance-fixed observation function without interruption. It can also automatically adapt to changes in the observation surface of the measured object and adjust the navigation trajectory to ensure that the underwater device can continuously and stably carry out automatic distance-fixed observation operations, taking into account both the flexibility of manual perspective adjustment and the stability of automatic observation operation. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein: Figure 1 A flowchart illustrating one embodiment of the distance observation method for underwater equipment provided in this application; Figure 2 A schematic diagram illustrating one implementation method of the underwater equipment's distance observation and cruise state provided in this application; Figure 3 This is a flowchart illustrating one implementation method for switching the observation surface of the object under test in this application. Figure 4 This is a flowchart illustrating one embodiment of step S220 of this application; Figure 5 This is a flowchart illustrating one embodiment of the automatic distance determination method for underwater equipment when the observation surface changes according to this application; Figure 6 This is a flowchart illustrating another embodiment of step S100 of this application; Figure 7 This is a schematic diagram of another implementation of the underwater equipment's distance observation cruise status provided in this application; Figure 8 This is a schematic diagram of the attitude adjustment stage in the underwater equipment of this application; Figure 9 This is a flowchart illustrating one implementation method of the present application for spatial coordinate transformation of a preset navigation path based on the spatial attitude of the observation surface after switching; Figure 10 This is a flowchart illustrating one implementation method of the underwater equipment continuing to perform automatic distance observation along the converted navigation path in this application; Figure 11 A schematic diagram of the underwater equipment provided in this application. Detailed Implementation

[0016] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0017] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0018] "A and / or B" includes the following three combinations: A only, B only, and a combination of A and B.

[0019] The use of "applies to" or "configured to" in this application implies open and inclusive language, which does not exclude the applicability to or configuration to devices performing additional tasks or steps. Additionally, the use of "based on" implies openness and inclusivity, because processes, steps, calculations, or other actions "based on" one or more of the stated conditions or values ​​may in practice be based on additional conditions or values ​​beyond those stated.

[0020] In this application, the term "exemplary" is used to mean "serving as an example, illustration, or description." Any embodiment described as "exemplary" in this application is not necessarily to be construed as being more preferred or advantageous than other embodiments. The following description is provided to enable any person skilled in the art to make and use this application. Details are set forth in the following description for purposes of explanation. It should be understood that those skilled in the art will recognize that this application can be made without using these specific details. In other embodiments, well-known structures and processes are not described in detail to avoid obscuring the description of this application with unnecessary detail. Therefore, this application is not intended to be limited to the embodiments shown, but is consistent with the broadest scope of the principles and features disclosed in this application.

[0021] It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0022] The fixed-range observation method of this application can be applied to underwater equipment. In this embodiment, the underwater equipment is equipped with at least a forward-facing multibeam sonar device and a depth sensor, enabling the underwater equipment to detect multiple parameters such as speed, distance, and depth. The underwater equipment is also equipped with a camera device to provide users with comprehensive visual observation. The forward-facing multibeam sonar device can be understood as a multibeam sonar device fixedly installed on the underwater equipment and aligned with the camera device; or a multibeam sonar device movably installed on the underwater equipment via an auxiliary device (such as a gimbal, bracket, etc.), which, after angle adjustment, can be aligned with the camera device. In a specific embodiment, the multibeam sonar device can be a Doppler Velocity Log (DVL). It is understood that in other embodiments, the underwater equipment may also be equipped with a lateral DVL and a downward DVL.

[0023] Furthermore, the underwater equipment includes, but is not limited to, underwater robots of the types such as remotely operated vehicles (ROVs) and autonomous remotely controlled vehicles (ARVs), and may also be underwater detection equipment, underwater submarine equipment or other underwater operation equipment. This application does not limit this.

[0024] For ease of understanding, this application uses a tethered remotely operated underwater vehicle (ROV) as an example to detail the specific implementation process. To ensure that the ROV can smoothly perform pitch angle adjustment and control observation tasks, achieve seamless integration between automatic distance cruise and manual pitch intervention, and avoid problems such as observation interruption, collision, and data loss, before the formal implementation of this application, it is necessary to complete the full parameter preset configuration of the ROV's automatic operation mode. This specifically covers three core modules: operation parameters, hardware configuration, and installation benchmark. All configuration parameters need to be specifically set according to the actual observation scenario, such as the observation of multiple continuous planar structures like ship corners and bridge piers. The specific configuration content is as follows: 1. Preset operation parameters: The ROV can be customized according to the actual underwater observation scenario requirements. Specifically, it can preset the target distance between the ROV and the underwater structure being measured, the observation area range, the navigation direction, the initial navigation path, the operating speed parameters, and the underwater operation safety threshold. At the same time, the ROV's observation start position and initial observation attitude can be dynamically configured according to the observation task requirements to adapt to the observation operation scenarios of different continuous planar structures such as bridge piers and ship hulls.

[0025] The fixed distance is the vertical distance from the center of the ROV (or the center of the main camera) to the surface of the object being measured. For example, if the fixed distance is set to 1 meter, the ROV will always try to maintain a vertical distance of 1 meter from the surface of the object being measured for observation.

[0026] The observation area refers to the specific boundary of the underwater structure that the ROV needs to observe.

[0027] Set the navigation direction or preset navigation path Pi: The preset navigation path consists of a series of three-dimensional spatial coordinate points, and the ROV will travel in the order of these points.

[0028] Set operating speed parameters: including the basic operating speed of ROV in the horizontal and vertical directions (towards / away from the object being measured), and support setting different speeds for different road sections.

[0029] Set safety thresholds: including collision warning distance, triggering a warning when the ROV is less than the distance to an obstacle, maximum pitch angle limit, and the maximum angle at which the ROV can safely tilt.

[0030] Among them, the observation start position and initial observation attitude can be dynamically set: After the ROV is launched into the water, its initial position and attitude can be adjusted according to the actual situation. The default initial attitude is horizontal and facing the surface of the object being measured (pitch angle ≈ 0°).

[0031] 2. Regarding hardware configuration, the ROV used in this application is equipped with at least a forward-facing multibeam sonar device. This forward-facing multibeam sonar device can be used to establish a real-time distance relationship between the ROV and the object being measured, i.e., to measure the vertical distance between the center of the ROV (or the center of the camera) and the surface of the object being measured. In a specific implementation, the multibeam sonar device, an underwater ranging and velocity sensing device operating based on the Doppler acoustic principle, directionally emits sound wave beams through a built-in acoustic transducer. After the sound waves contact the surface of the underwater structure being measured, they form reflected echoes. After receiving the echo signals, the device combines the sound wave propagation time, propagation delay, and Doppler frequency shift changes to calculate the straight-line distance, relative position, and relative motion state between the device and the object being measured.

[0032] Furthermore, in this embodiment, the forward-facing multibeam sonar device of the underwater equipment is equipped with at least three acoustic transducers. The acoustic transducers actively transmit acoustic signals and receive acoustic echo signals reflected by the object being measured, which can accurately calculate the real-time relative distance between the ROV carrier and the target structure being measured, thereby achieving high-precision ranging.

[0033] 3. This application sets a fixed equipment installation benchmark, keeps the detection angle of the forward DVL consistent with the observation angle of the main camera on the ROV, ensures that the ranging angle and the imaging angle are matched, and establishes a vertical distance correlation between the center of the ROV or the center of the camera and the surface of the object being measured in real time. Vertical distance data is collected throughout the process, providing accurate data support for subsequent distance correction after attitude adjustment, cross-surface recognition, and navigation path coordinate transformation.

[0034] Please combine Figure 1 , Figure 1 This is a flowchart illustrating one embodiment of the distance observation method for underwater equipment in this application, as shown below. Figure 1 The distance observation method provided in this application includes the following steps: S100 performs manual pitch angle adjustment in automatic distance observation mode. During pitch angle adjustment, it maintains the preset vertical distance between the underwater equipment and the current observation surface of the object under test based on the multi-beam slant range data collected by the forward multi-beam sonar equipment.

[0035] Please combine further Figure 2 , Figure 2 This is a schematic diagram of the distance observation and cruise status of the underwater equipment provided in this application, such as... Figure 2In one specific application scenario, when an ROV travels along a predetermined path to a corner area formed by the intersection of adjacent planes such as the hull or hull, it can perform specialized and detailed observations of the weld structure, surface attachments, and transition areas within that area. Operators can directly adjust the ROV's pitch angle in the automatic distance observation mode, manually maneuvering it upwards or downwards to precisely align the onboard sensors and camera equipment with the corner area to be measured, thus acquiring high-definition observation images.

[0036] During the ROV's journey from position A to position B, the ROV strictly follows the pre-set navigation path to carry out automatic navigation operations. During this process, the ROV and the object being measured maintain a stable relative observation attitude that is horizontal and facing each other. The distance monitoring during this operation phase is achieved by the onboard forward DVL, thereby defining the relative distance between the ROV and the object being measured in real time.

[0037] In the actual ranging application of this scheme, the ranging method can include two implementation forms. The first is to directly use the detection data collected by the forward DVL to calculate the vertical distance between the forward DVL probe and the surface of the object being measured. The second is to combine the actual installation position and layout coordinates of the forward DVL in the ROV's own coordinate system, and calculate the distance between the ROV observation reference center and the object being measured based on the measured ranging data of the forward DVL. This scheme preferentially adopts the second ranging method as the core ranging strategy. Furthermore, when the ROV sails to position B, the operator manually intervenes to adjust the pitch angle of the ROV according to the actual observation needs. Figure 2 As shown, the ROV's movement from position B to position D is a phase where the operator continuously adjusts its attitude manually. During actual operation, the operator can flexibly change the ROV's pitch angle using the joystick on the remote control. Taking a horizontal initial attitude as an example, this application sets the pitch angle adjustment threshold to ±45°. Of course, in other embodiments, the pitch angle adjustment threshold can be set to other thresholds, such as ±50°, ±55°, ±60°, etc., which are not specifically limited here. During actual adjustment, if the pitch angle is adjusted to near the threshold range, such as 40°, the remote control can simultaneously emit an audible and visual warning signal to remind the operator that the current pitch angle is approaching the maximum adjustment range corresponding to the current observation face.

[0038] Understandably, throughout the entire process of manually adjusting the pitch angle, the equipment always operates in automatic distance observation mode. The system continuously relies on forward DVL to collect multibeam slant range data and maintains the preset vertical distance between the ROV and the current observation surface in real time. The attitude adjustment process will not completely exit the automatic distance control logic, nor will it interrupt the established navigation observation task. The following section details the automatic distance determination method between the ROV and the measured object throughout the entire process of manually adjusting the pitch angle.

[0039] Furthermore, when the operator continuously adjusts the ROV's pitch angle beyond the preset ±45° adjustment threshold, the system automatically determines that the operator's observation intention has changed and is no longer focusing on the original observation plane, thus automatically triggering the observation plane switching and adaptation logic. For example... Figure 2 The ROV attitude corresponding to position D is the critical limit attitude for adjusting the pitch angle upwards to the preset adjustment threshold. This attitude still fits the original observation plane and has not yet triggered the observation plane switching action. It should be noted that the ±45° listed in this scheme is only an exemplary adjustment threshold and is not a limitation on the scope of protection of this application. In actual engineering applications, the pitch angle adjustment limit threshold can be configured to other angle values ​​such as 60° according to the shape characteristics of the underwater structure under test, the corner angle conditions, and the observation operation requirements, while the overall control logic remains unchanged.

[0040] S200: When the pitch angle of the underwater device exceeds the preset threshold and the observation surface of the object being measured is switched based on the multibeam slant range data, the preset navigation path is transformed into spatial coordinates according to the spatial attitude of the observation surface after the switch, so that the underwater device continues to perform automatic distance measurement along the transformed navigation path.

[0041] Furthermore, when the pitch angle of the underwater ROV exceeds the preset threshold after manual adjustment during automatic distance observation, the system will determine that the observation surface of the object being measured has changed based on the multi-beam slant range data collected by the forward multi-beam sonar. For example, it may switch from the original observation surface to an adjacent new observation surface of a continuous structure such as a ship's corner or a bridge pier.

[0042] To adapt to the spatial attitude of the new observation surface, the system will perform spatial coordinate transformation on the pre-planned navigation path, so that the navigation path matches and aligns with the azimuth and angle of the new observation surface. This will then control the underwater equipment to continue operating along the transformed navigation path, ensuring uninterrupted automatic distance observation throughout the entire process, thus guaranteeing the continuity and stability of observation of multi-faceted underwater structures.

[0043] Please combine further Figure 3 , Figure 3 This is a flowchart illustrating one implementation method of switching the observation surface of the object being measured in this application, as shown below. Figure 3In this application, the switching of the observation surface of the object under test is the core sub-step of step S200, which is specifically achieved through the following process: S210: When the pitch angle of the underwater equipment exceeds the preset threshold, perform simultaneous horizontal comparison and time-series vertical comparison of the multibeam slant range data.

[0044] Furthermore, during the process of adjusting the ROV's pitch angle, the three acoustic detection beams emitted forward by the DVL will change their projection orientation as the equipment's attitude deflects, resulting in two different projection states: First, all three detection beams are projected onto the same observation plane of the object being measured. This indicates that the current observation plane has not been switched and the equipment is still conducting detection operations on the original observation plane. Secondly, the three detection beams are projected onto multiple different observation planes of the object under test. This state only indicates that the detection angle of the equipment has entered the corner area where adjacent planes meet, which is a transitional state in which the observation plane is about to switch. At this time, the switching of the observation plane has not yet been officially determined.

[0045] Specifically, for observation scenarios involving two continuous, interconnected planes, such as ship corners, this application requires combining the ROV's real-time pitch angle with a two-way comparison of beam data to comprehensively determine whether the current observation plane has switched. The two-way comparison includes a comparison of lateral differences in beam data at the same moment, and a vertical comparison of the changing trends of single beam data over different time periods. This accurately distinguishes the plane to which the beam's landing point belongs, thus completing the observation plane status determination. The specific determination is as follows: Please combine further Figure 4 , Figure 4 This is a flowchart illustrating an embodiment of step S220 of this application, as shown below. Figure 4 In this application, S220 further includes the following sub-steps: S221, calculate the relative deviation between the slant range of each beam and its average value at the same time. When the relative deviation exceeds the preset lateral threshold, it is identified as a lateral abnormal beam.

[0046] Referring to the temporal beam slant range example in Table 1, the synchronous lateral comparison used in this application involves comparing and analyzing the slant range data of multiple beams at the same acquisition time to identify beams with numerical anomalies at the current time. Specifically, the slant range data of each beam acquired by forward DVL at the same time are obtained, the average value of all beam slant ranges is calculated, the absolute deviation of each beam slant range from the average value is calculated, and the relative deviation percentage is obtained based on the ratio of the absolute deviation to the average value. When the relative deviation percentage of a certain beam exceeds a preset lateral threshold, the beam is identified as a laterally abnormal beam.

[0047] Table 1. Example data of time-series beam slant range Table 1 shows that at time T1, the slant range of beam 1 is 0.9m, the slant range of beam 2 is 0.87m, and the slant range of beam 3 is 0.93m. The slant range values ​​of the three beams are relatively close, and there is no obvious lateral anomaly. Combined with the historical data of each beam, there is no obvious jump in the slant range, which confirms that the three beams are all projected onto the same measured surface A.

[0048] At time T2, the slant range of beam 3 begins to increase. A lateral comparison calculation is performed on the data at this time: First, the average slant range of the three beams is calculated: (0.91+0.89+0.97) / 3≈0.9233m; Furthermore, the absolute deviation of each beam from the average value is calculated: Beam 1 has a wavelength of |0.91 - 0.9233| = 0.0133 m; Beam 2 has a wavelength of 0.0333 m; Beam 3 has a wavelength of 0.0467 m. Finally, the relative deviation percentage of each beam was calculated; beam 1 was 0.0133 / 0.9233×100%≈1.44%; beam 2 was about 3.61%; beam 3 was 5.06%, and the maximum relative deviation at that moment was 5.06%.

[0049] In this application, the lateral anomaly threshold can be preset to 15%. At this point, the relative deviation of beam 3 is at its maximum but does not reach the preset anomaly threshold, and is generally within a reasonable range. Corresponding to the actual operation scenario, this can be understood as the underwater equipment gradually approaching the corner edge. Beam 3 is the first to sense the distance change, but has not left the measured surface A, which is a normal transition state. Combined with the longitudinal comparison results, the temporal change rate of each beam is normal and there are no jumps. It can be determined that the three beams are still projected onto the measured surface A, and beam 3 may be projected onto the transition area of ​​the measured surface A (such as a depression).

[0050] At time T3, the slant range of beam 3 increased significantly. The calculated relative deviation reached 17.7%, exceeding the preset lateral threshold of 15%. At this time, beam 3 was determined to be an abnormal lateral beam.

[0051] At time T4: the slant ranges of the three beams are 0.89m, 0.89m, and 1.18m, respectively, with an average value of ≈0.987m. The relative deviation of beam 3 is ≈19.6% >15%, continuously triggering lateral anomalies. The rate of change of beam 3 is 0.3m / s, and it returns to smoothness, further confirming that beam 3 has stabilized on the measured surface B, while beams 1 and 2 are still hitting the measured surface A.

[0052] S222, the temporal change rate is determined based on the slant range data of the same beam at different acquisition times. When the temporal change rate exceeds the preset longitudinal threshold, it is determined to be a longitudinally abnormal beam.

[0053] Furthermore, the longitudinal temporal comparison is used to perform temporal tracking analysis on the slant range data of the same beam at continuous acquisition times. By calculating the temporal change rate of slant range, it is determined whether a data jump has occurred, thereby identifying whether the beam has deviated from the original observation plane.

[0054] The specific determination rule is as follows: Select the slant range data of the same beam at adjacent acquisition times, and calculate its slant range using the formula: slant range at the current time - slant range at the previous time ÷ sampling interval; combine the mean and standard deviation of the historical slant range to set a longitudinal anomaly threshold. When the slant range exceeds the preset longitudinal anomaly threshold, it is determined that the beam has experienced a data jump and is identified as a longitudinal anomaly beam.

[0055] The specific calculation process for the longitudinal comparison is as follows: Taking a sampling interval of 0.1 seconds as an example, based on the data of T1 and T2, the timing change rate of beam 1 is (0.91-0.9) / 0.1=0.1m / s; the timing change rate of beam 2 is (0.89-0.87) / 0.1=0.2m / s; and the timing change rate of beam 3 is (0.97-0.93) / 0.1=0.5m / s.

[0056] To determine whether the time series change rate is a jump, it is necessary to refer to the historical time series data of each beam: Assuming that in the previous sampling periods before T1, the average change rate of each beam is about 0.3 m / s and the standard deviation is about 0.2 m / s; use twice the standard deviation (0.4 m / s) as the longitudinal anomaly threshold. Of course, other values ​​can be set in other implementations, and no specific limitation is made here.

[0057] Furthermore, the difference between the temporal change rate of each beam and the historical average was calculated: beam 1 differed from the historical average by 0.2 m / s, beam 2 by 0.1 m / s, and beam 3 by 0.2 m / s. None of the three differences exceeded the longitudinal anomaly threshold of 0.4 m / s. Therefore, it can be confirmed that there was no jump in the slant range of each beam from time T1 to T2.

[0058] A comprehensive judgment based on data from various time points: From time T1 to T2: the time change rate of each beam is within the normal range and no jump occurs. Combined with the lateral comparison results, it can be determined that all three beams are projected onto the measured surface A, and only beam 3 is in the transition region of the measured surface A. At time T3: The slant range of beam 3 experiences a step increase, with a temporal change rate reaching 1.8 m / s, far exceeding the preset longitudinal anomaly threshold of 0.4 m / s, triggering a longitudinal anomaly. Simultaneously, combined with the lateral comparison results, the relative deviation of beam 3 at this time reaches 17.7%, exceeding the preset lateral anomaly threshold of 15%, triggering a lateral anomaly. The simultaneous presence of both lateral and longitudinal anomalies pointing towards beam 3 confirms that beam 3 has jumped from the measured surface A to the measured surface B, while beams 1 and 2 are still projected onto the measured surface A.

[0059] At time T4: the temporal change rate of beam 3 dropped back to 0.3 m / s, and the data returned to smoothness after the jump; in the lateral comparison, the relative deviation of beam 3 reached 19.6%, which continued to exceed the lateral anomaly threshold, further confirming that beam 3 had stably jumped to the measured surface B, while beams 1 and 2 were still projected onto the measured surface A.

[0060] In the above embodiments, by combining simultaneous horizontal comparison and temporal longitudinal comparison, beam anomaly status can be accurately identified from two dimensions: the difference in multi-beam data at the same time and the temporal change trend of single beam. This effectively avoids the misjudgment and omission problems that are prone to occur in single-dimensional comparison, and greatly improves the accuracy and reliability of observation surface switching determination. It can quickly adapt to complex folding surface scenarios such as underwater bridge piers and ship corners, ensuring timely identification of beam jumps during observation surface transition and switching, ensuring the continuity and stability of underwater equipment's distance observation, and effectively reducing the risk of target loss and collision.

[0061] S220: When at least two sets of beams simultaneously exhibit lateral and longitudinal anomalies, it is confirmed that the observation surface of the measured object has switched.

[0062] Furthermore, after completing the two-dimensional data comparison and beam anomaly determination, if two or more beams are identified on site, and both the horizontal anomaly determination condition and the vertical anomaly determination condition are met at the same time period, and the pitch angle of the underwater equipment exceeds the preset threshold, such as the pitch angle exceeding 45°, it can be accurately determined that the observation surface corresponding to the measured object has been switched, which can be used as the preliminary determination basis for adjusting the navigation path.

[0063] The automatic distance determination process of underwater equipment is described in detail below for the following situations: when the observation surface has not been switched, when the observation surface is in the transitional state of switching, and after the observation surface has been switched. I. The observation plane did not change. Please combine further Figure 5 , Figure 5 This is a flowchart illustrating one embodiment of the automatic distance determination method for underwater equipment when the observation surface changes. It is understood that in this embodiment, after the user manually adjusts the pitch angle, the observation surface of the measured object does not change, and the multiple beams emitted by the forward DVL are all projected onto the same observation surface. At this time, the plane fitting calculation can be completed using the geometric principle that three non-collinear points in space can uniquely determine a plane, thereby completing distance measurement and position control. The specific description is as follows: Figure 5 Step S100 includes the following sub-steps: S110, the plane equation of the current observation surface is obtained by fitting the multibeam slant range data.

[0064] For example, by using forward DVL to obtain the slant range values ​​L1, L2, and L3 corresponding to the three detection beams in real time, and then retrieving the precise installation position parameters of the three acoustic transducers in the ROV's own coordinate system after factory calibration, and combining the beam detection azimuth and the measured slant range, the three-dimensional coordinates P1(x1,y1,z1), P2(x2,y2,z2), and P3(x3,y3,z3) corresponding to the reflection points of the three beams on the measured surface are calculated.

[0065] Finally, mathematical operations are performed using three sets of spatial coordinates to derive the mathematical expression of the spatial plane corresponding to the currently measured observation surface, that is, to obtain the standard plane equation of the observation surface in the form of Ax+By+Cz+D=0, thus completing the plane fitting operation.

[0066] S120, the actual vertical distance from the center of the underwater equipment to the current observation surface is calculated based on the plane equation.

[0067] This application sets the origin of the ROV's own coordinate system as the central reference position of the underwater equipment. After obtaining the plane equation of the observed surface, the distance calculation formula from a spatial point to a spatial plane is applied. The central reference coordinates of the equipment and the plane equation parameters are substituted to accurately calculate the actual vertical distance between the center of the underwater equipment and the current observed surface.

[0068] S130 adjusts the position of the underwater equipment in real time based on the difference between the actual vertical distance and the preset vertical distance to maintain the preset vertical distance unchanged.

[0069] Furthermore, the calculated actual vertical distance is compared with the preset standard observation vertical distance in the system to solve the distance difference between the two. Based on the difference, the position of the underwater equipment in the depth direction is adjusted in real time to offset the distance deviation caused by water flow interference and attitude fine-tuning. This ensures that the distance between the underwater ROV and the observed surface remains stable at the preset vertical distance value, achieving uninterrupted and continuous automatic distance control during manual adjustment of pitch attitude.

[0070] In the above embodiments, by using the three-point fixed-plane geometry principle to achieve accurate fitting of the observation surface, the true vertical distance from the center of the equipment to the observation surface can be accurately calculated, effectively avoiding the measurement deviation caused by single slant range measurement. It can quickly compare the difference between the actual distance and the preset distance and complete the position adaptive adjustment. Even when manually adjusting the pitch angle to change the detection angle, the standard observation distance can be stably maintained, greatly improving the distance control accuracy and operational stability, and ensuring the continuous and stable operation of underwater observation.

[0071] II. In the transitional state of observation surface switching Please combine further Figure 6 , Figure 6This is a flowchart illustrating another implementation of step S100 of this application. It can be understood that in this embodiment, the three detection beams emitted by the forward-facing DVL are dispersed and projected onto multiple different observation planes of the object being measured. This state only indicates that the underwater vehicle's (ROV) detection perspective has entered the corner area where adjacent planes meet, representing a transitional state where the observation plane is about to switch. At this time, the system has not yet formally determined that the observation plane switch has been completed. For example... Figure 2 During the artificial pitch angle adjustment phase from position B to position D, the underwater equipment is in a transitional state of observation surface switching. Multiple probe beams have been dispersed and projected onto different observation planes of the object being measured, and the conditions for formally switching observation surfaces have not yet been met. In this condition, the distance is no longer calculated using a three-point fitting method to complete the observation surface. Instead, a temporary reference plane is used to maintain the distance during the pitch angle adjustment process. Based on this transitional condition, to ensure uninterrupted distance control and maintenance of the preset vertical distance during pitch angle adjustment, the following steps are followed to achieve distance maintenance: First, let's clarify the core premise: In this transitional state, the system will not initiate the observation surface switching process, but will only maintain the distance through a temporary reference plane. The specific steps are as follows: When the underwater equipment is determined to be in a transitional observation plane switching condition, multiple sets of detection beams have been dispersed and projected onto adjacent different observation planes, but the complete set of formal switching judgment conditions, such as angle thresholds and beam verification, have not yet been met. Therefore, the conventional three-point coplanar fitting method cannot be used to construct a standard observation plane. Under this condition, a preset temporary benchmark is used to adapt to the transitional detection scenario, achieving a closed-loop maintenance of the preset vertical distance between the underwater equipment and the area to be measured, without interrupting the original automatic distance-fixing observation operation link. The specific step-by-step implementation method is as follows: S101, a temporary reference plane is constructed based on the effective beam slant range data and the historical attitude normal vector.

[0072] Based on the results of previous two-way comparison and verification of multi-beam data, all real-time transmitted raw beam slant range data were precisely screened and categorized. Valid detection data accurately projected onto the new observation surface to be switched was extracted separately; this compliant detection data was uniformly defined as valid beam slant range data. Simultaneously, the reference parameters stored in the local cache of the control system were retrieved, and the dedicated attitude normal vectors corresponding to the original complete observation surface, which had not undergone deflection switching and were retained and solidified during the initial steady-state observation phase, were called to ensure that the spatial orientation of the original observation reference remained unchanged. The valid beam slant range data refers to the beam slant range data projected onto the observation surface after the switch.

[0073] Furthermore, based on the measured slant range values ​​corresponding to the effective beam, the fixed installation points of each acoustic transducer, after factory calibration and verification within the ROV's body coordinate system, are matched to accurately calculate and fit the three-dimensional coordinates of the actual reflection point of the effective beam on the observation surface to be switched. This, combined with the retained historical attitude normal vector constraining the overall spatial orientation reference, is used to complete the calculation in a coordinated and coupled manner, constructing a dedicated temporary reference plane adapted to complex detection scenarios involving corner transitions. This plane serves as the sole reliable ranging reference carrier during the transition period. The historical attitude normal vector is the attitude normal vector corresponding to the original observation surface retained before the observation surface switch.

[0074] S102, calculate the actual vertical distance from the center of the underwater equipment to the temporary reference plane based on the temporary reference plane.

[0075] In this embodiment, the unified and fixed ranging benchmark standard of this underwater observation scheme is used throughout the entire process. The origin of the ROV's own coordinate system is always calibrated as the core center benchmark point of the underwater equipment, without any additional changes to the ranging reference coordinates. After the temporary reference plane is constructed, the corresponding standardized spatial plane mathematical expression is generated simultaneously. The industry-standard and compliant formula for calculating the vertical distance from a spatial point to a spatial plane is applied. The fixed benchmark coordinates of the underwater equipment center and the complete set of calculation parameters of the temporary reference plane are then substituted into the formula. The actual measured vertical distance between the underwater equipment center and the temporary reference plane under real-time operating conditions is calculated with high precision, providing accurate and reliable raw ranging data support for subsequent closed-loop distance control.

[0076] S103, based on the difference between the actual vertical distance and the preset vertical distance, adjust the position of the underwater device in real time to maintain the preset vertical distance unchanged.

[0077] Furthermore, the actual vertical distance parameters calculated in real time during the transition period are precisely compared and calibrated with the pre-set standard observation vertical distance parameters that the system had previously fixed. This allows for rapid calculation of the precise deviation between the two sets of distance parameters, while simultaneously determining the specific directional trend of the distance offset. Based on this precise distance deviation, the underwater equipment's main control system quickly generates closed-loop position fine-tuning control commands adapted to the current pitch fine-tuning conditions. This real-time adjustment of the underwater equipment's working points in the depth direction precisely compensates for small distance offset errors caused by attitude fine-tuning and corner current disturbances. This ensures that throughout the entire manual pitch adjustment process from B to D, the ROV maintains a constant preset vertical distance and stably maintains normal operation in the automatic distance observation mode.

[0078] Understandably, the transition from B to C is a mild initial stage. At point B, the pitch angle is manually adjusted by manipulating the joystick, but the adjustment angle is too small and far from reaching the preset threshold. During this stage, most beams remain on the original observation plane, with only a few beams slowly approaching the corner edge. The slant range data changes gradually without significant jumps, large-scale beam separation, or both lateral and longitudinal anomalies. The system does not determine that a plane change is imminent. Therefore, the ranging method in this stage still mainly uses the three-point plane fitting algorithm, with only minor adaptive distance corrections. There is no need to remove beams or build a dedicated temporary reference plane for the time being.

[0079] In the above embodiments, by constructing a temporary reference plane based on effective beam slant range data and historical attitude normal vectors during the observation plane switching transition phase, and then calculating the actual vertical distance from the equipment center to the plane and adjusting the equipment position in real time according to the distance difference, the technical solution can achieve uninterrupted range control under beam cross-plane projection conditions, smoothly connect the observation plane switching process, ensure uninterrupted range observation throughout the pitch angle adjustment process, and improve the continuity and operational stability of underwater observation operations in complex corner areas.

[0080] III. Distance determination based on the new observation surface after switching Furthermore, before performing spatial coordinate transformation on the preset navigation path based on the spatial attitude of the observed surface after the switch, the following is also included: The pitch attitude of the underwater equipment is corrected based on multibeam slant range data so that the underwater equipment is facing the switched observation surface; the angle formed by the underwater equipment relative to the horizontal reference attitude is taken as the final pitch angle.

[0081] Understandably, after determining that the observation surface has officially switched over, the system no longer directly uses the pitch adjustment angle obtained by the operator's manual control. Instead, it uses the spatial azimuth and normal orientation of the switched observation surface, calculated from multibeam slant range data, as a calibration benchmark to autonomously and accurately correct the current actual pitch attitude of the underwater equipment. The pitch angle obtained by the operator through the remote control is only a preliminary adjustment angle, representing only the attitude adjustment command angle issued by human intervention, and is not equivalent to the standard angle at which the underwater equipment's observation view is precisely aligned with the switched observation surface.

[0082] For example, when the operator manually adjusts the underwater equipment downwards to a 55° pitch angle, although the observation surface switching determination has been completed, this 55° is only a manually controlled angle and cannot ensure that the underwater equipment's detection center and camera observation angle are perpendicularly aligned with the measured surface B. At this time, the system uses the spatial orientation of the switched observation surface as a reference benchmark and autonomously performs a secondary fine-tuning correction on the equipment's pitch attitude, gradually adjusting the equipment's tilt angle until the overall observation orientation of the underwater equipment is completely perpendicularly aligned with the measured surface B. Once the equipment reaches a precise alignment state, the actual tilt angle formed by the underwater equipment relative to the horizontal reference attitude is collected, and this actual angle after attitude correction is determined as the final pitch angle θ. This final pitch angle θ is the effective attitude angle for the equipment to accurately adapt to the new observation surface. When performing spatial coordinate transformation calculations for the navigation path, this corrected final pitch angle is used as the core angle parameter, rather than directly using the initial pitch angle manually adjusted by the user.

[0083] Combination Figure 7 , Figure 7 This is a schematic diagram of another implementation of the fixed-distance observation cruise state of the underwater equipment provided in this application. When the underwater ROV is at position C, the pitch angle adjusted by the user exceeds 45° and at least two beams in the forward DVL (Directional Vehicle Range) hit the observation surface B. At this time, the observation surface changes, and an adjusted navigation path needs to be formed by combining the original navigation path and the pitch angle of the ROV facing the observation surface B. During the pitch angle adjustment process, no user intervention is required; confirmation can be achieved by combining the slant range analysis of the three beams. The ROV faces the observation surface B at position D, maintains the set fixed distance, and then automatically performs observations of the observation surface B according to the adjusted navigation path.

[0084] Combination Figure 8 , Figure 8 This is a schematic diagram of the attitude adjustment stage in the underwater equipment of this application. Position s1 is the moment when the user intervention disappears, that is, the node when the operator stops manually adjusting the pitch angle and no longer makes manual intervention.

[0085] During the s1–s3 phase, the ROV's travel plan is based on two criteria: first, it follows the original preset navigation path in a horizontal direction to ensure that the travel trajectory does not deviate from the overall observation area; second, it automatically adjusts its position in the depth direction (towards or away from the measured surface B) based on the multi-beam slant range data collected in real time by forward DVL. During this phase, the distances d2 and d3 between the ROV and the measured surface B can be consistent with the preset distance d1, or there can be slight deviations depending on the attitude adjustment requirements, all of which are normal transition states.

[0086] When the ROV reaches position s3, its pitch attitude has been autonomously corrected and it is completely facing the measured surface B. The system then generates an adjusted navigation path adapted to the new observation surface B, preparing the path for subsequent routine observations.

[0087] After entering the s3–s4 phase, the ROV switches its travel reference, taking the horizontal running direction of the adjusted navigation path as the core, and continues to make fine adjustments to the distance in the depth direction in conjunction with the real-time distance measurement data obtained by forward DVL, until the distance between the center of the ROV and the measured surface B accurately reaches the preset distance value d1.

[0088] Once the ROV reaches position s4, it officially enters the stable observation phase, and performs automatic distance observation operations on the measured surface B according to the adjusted navigation path throughout the entire process.

[0089] Further integration Figure 9 , Figure 9 This is a flowchart illustrating one implementation method of spatial coordinate transformation of a preset navigation path based on the spatial attitude of the switched observation surface, as described in this application. It is understood that after identifying the switched observation surface B, the system recalculates the vertical distance from the ROV to the switched observation surface B and maintains the preset distance; simultaneously, using the actual pitch angle of the ROV directly facing the switched observation surface B as the rotation angle, a rotation matrix is ​​used to perform an overall coordinate transformation on the original preset navigation path, generating a new navigation path adapted to the current attitude. The entire process runs automatically without interruption, and retains the original path's operating parameters. Specifically: S201, construct the rotation matrix based on the final pitch angle.

[0090] Furthermore, using the initial attitude coordinate system of the underwater ROV as a reference, the final pitch angle θ corresponding to the observation surface after autonomous attitude correction and precise switching of the device is used as the core angle parameter to construct a spatial rotation matrix R(θ) around the device's own Y-axis.

[0091] S202, based on the rotation matrix, perform spatial rotation transformation on the coordinates in the preset navigation path to obtain the transformed navigation path; wherein, the transformed navigation path retains at least some of the operating parameters of the preset navigation path unchanged.

[0092] Furthermore, the system calls the original preset navigation path point set Pi stored inside the device, and relies on the spatial coordinate transformation calculation formula Pi′=R(θ)⋅Pi. Using the completed rotation matrix around the Y-axis, it performs a unified spatial rotation transformation on all coordinate points of the original path. The new path point set Pi′ obtained after the transformation is the navigation path after the change of the observation surface attitude.

[0093] During the path coordinate attitude adaptation process, the system does not modify all operating rules. It retains core operating parameters such as travel speed and basic cruise logic from the original preset navigation path, adjusting only the overall direction of travel based on the spatial attitude of the new observation surface. After the coordinate transformation is complete, the underwater equipment directly follows the transformed navigation path and continues automatic navigation and observation. It smoothly transitions from the original observation mode to the new observation surface cruise mode. The entire path switching and attitude adaptation process is seamlessly connected, with no operational interruptions or navigation pauses, continuously completing the automatic distance observation task.

[0094] The above implementation method, by building a rotation matrix based on the corrected standard pitch angle and performing spatial rotation transformation on the original navigation path, can quickly complete the adaptive matching of the navigation path and the attitude of the new observation surface without changing the original core operating parameters, perfectly connect multiple continuous plane observation scenarios, and ensure the smooth and continuous operation of underwater cruise observation operations throughout the entire process.

[0095] Please refer to further information. Figure 10 , Figure 10 This is a flowchart illustrating an implementation method of automatic distance observation performed by the underwater equipment along the converted navigation path, and this embodiment is a further extension of step S200, which further includes the following sub-steps: S210a, the plane equation of the observation surface after switching is obtained by fitting the multibeam slant range data.

[0096] During normal cruising along the switched navigation path, the forward DVL continuously collects slant range data of the three beams projected onto the switched observation surface. Combined with the factory-calibrated installation positions of each acoustic transducer within the underwater equipment's own coordinate system and the beam detection azimuth, the three-dimensional coordinates of the reflection points of the three beams on the switched observation surface are calculated. Using these three sets of spatial coordinates for fitting calculations, the standard spatial plane equation corresponding to the switched observation surface is obtained, serving as the reference plane for distance measurement under the new observation surface.

[0097] S220a, the actual vertical distance from the center of the underwater equipment to the observation surface after switching is calculated based on the plane equation.

[0098] Furthermore, using the origin of the underwater equipment's own coordinate system as the reference position of the equipment center, the plane equation parameters of the switched observation surface and the reference coordinates of the equipment center are substituted into the formula for calculating the vertical distance from a spatial point to a plane, so as to accurately calculate the real-time actual vertical distance between the center of the underwater equipment and the switched observation surface.

[0099] S230a adjusts the position of the underwater equipment in real time based on the difference between the actual vertical distance and the preset vertical distance to maintain the preset vertical distance unchanged.

[0100] The actual vertical distance measured in real time is compared with the preset vertical distance stored in the system to calculate the distance deviation value and offset direction. The equipment adjusts its position in the depth direction based on the deviation and corrects the distance error generated during navigation in real time. This ensures that the underwater equipment maintains a fixed preset vertical distance with the switched observation surface throughout the entire observation process along the switched navigation path, and stably completes the routine automatic distance measurement observation task.

[0101] The underwater equipment pitch angle adjustment control observation scheme proposed in this application allows operators to manually adjust the equipment's pitch attitude in real time without exiting the automatic distance observation mode. It adapts to different working conditions such as conventional observation, mild and critical transitions by relying on three-point plane fitting and temporary reference plane distance setting. At the same time, it accurately identifies the beam status and observation surface switching timing by simultaneously comparing multi-beam data in the horizontal and temporal longitudinal directions. Combined with attitude autonomous correction to eliminate manual adjustment angle deviations, and with the help of a rotation matrix to complete the adaptive transformation of navigation path spatial coordinates while retaining the original core operating parameters, it achieves seamless adaptation between the observation perspective and the navigation trajectory. The entire navigation is uninterrupted and the observation is uninterrupted. It effectively solves the problems of easy disconnection of distance setting during attitude adjustment, discontinuous observation in multi-faceted scenarios, and inability to adaptively adjust the path in traditional methods. It significantly reduces the risk of underwater collisions and the probability of losing observation targets. It takes into account the stability of automatic cruise operation and the flexibility of manual attitude adjustment. It can be well adapted to the fine observation scenarios of multi-continuous planar underwater structures such as hulls and bridge piers, and comprehensively improves the continuity, accuracy and overall practicality of underwater distance observation operations.

[0102] Those skilled in the art will understand that, in the above-described method of the specific implementation, the order in which each step is written does not imply a strict execution order and does not constitute any limitation on the implementation process. The specific execution order of each step should be determined by its function and possible internal logic.

[0103] Reference Figure 11 The diagram below provides a structural schematic of the underwater equipment for the embodiments of this application.

[0104] The underwater device may include: a processor 1001, such as a central processing unit (CPU), a communication bus 1002, a user interface 1003, a network interface 1004, and a memory 1005. The communication bus 1002 is used to enable communication between these components. The user interface 1003 may include a display screen or an input unit such as a keyboard; optionally, the user interface 1003 may also include a standard wired interface or a wireless interface. The network interface 1004 may optionally include a standard wired interface or a wireless interface (such as a Wi-Fi interface). The memory 1005 may be a high-speed random access memory (RAM) or a stable non-volatile memory (NVM), such as a disk drive. Optionally, the memory 1005 may also be a storage device independent of the aforementioned processor 1001.

[0105] Those skilled in the art will understand that Figure 11 The structure shown does not constitute a limitation on the underwater equipment and may include more or fewer components than shown, or combine certain components, or have different component arrangements.

[0106] like Figure 11 As shown, the memory 1005, which serves as a storage medium, may include an operating system, a network communication module, a user interface module, and a control program for underwater equipment.

[0107] exist Figure 11 In the underwater device shown, the network interface 1004 is mainly used for data communication with other devices; the user interface 1003 is mainly used for data interaction with the user; the processor 1001 and memory 1005 in the underwater device of this application can be set in the underwater device. The underwater device calls the control program of the underwater device stored in the memory 1005 through the processor 1001 and executes the above-mentioned fixed-distance observation method.

[0108] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0109] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0110] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes several instructions to cause a terminal device (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods of the various embodiments of this application.

[0111] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A method for fixed-range observation of an underwater device, wherein the underwater device is equipped with at least a forward-facing multibeam sonar device, characterized in that, The method includes: In response to the manual pitch angle adjustment command in the automatic distance observation mode, and during the pitch angle adjustment process, based on the multi-beam slant range data collected by the forward multi-beam sonar device, the preset vertical distance between the underwater device and the current observation surface of the object under test is maintained. When the pitch angle of the underwater device exceeds a preset threshold and the observation surface of the measured object is switched based on the multibeam slant range data, the preset navigation path is transformed into spatial coordinates according to the spatial attitude of the observation surface after the switch, so that the underwater device continues to perform automatic distance observation along the transformed navigation path.

2. The method according to claim 1, characterized in that, The confirmation that the observation plane of the object under test has switched includes: When the pitch angle of the underwater device exceeds a preset threshold, the multibeam slant range data is compared simultaneously in the horizontal direction and in the longitudinal direction over time. When at least two sets of beams simultaneously exhibit lateral and longitudinal anomalies, it is confirmed that the observation surface of the object under test has switched.

3. The method according to claim 2, characterized in that, The process of performing simultaneous horizontal comparison and time-series vertical comparison of the multi-beam slant range data includes: Calculate the relative deviation between the slant range of each beam and its average value at the same time. When the relative deviation exceeds a preset lateral threshold, it is determined to be a laterally abnormal beam. The temporal change rate is determined based on the slant range data of the same beam at different acquisition times. When the temporal change rate exceeds a preset longitudinal threshold, it is determined to be a longitudinally abnormal beam.

4. The method according to claim 1, characterized in that, When the observation surface of the object being measured does not change, maintaining a preset vertical distance between the underwater device and the current observation surface of the object being measured, based on the multibeam slant range data collected by the forward multibeam sonar device, includes: The plane equation of the current observation surface is obtained by fitting the multibeam slant range data; The actual vertical distance from the center of the underwater equipment to the current observation surface is calculated based on the plane equation. Based on the difference between the actual vertical distance and the preset vertical distance, the position of the underwater device is adjusted in real time to maintain the preset vertical distance unchanged.

5. The method according to claim 1, characterized in that, When in the observation surface switching transition state, maintaining the preset vertical distance between the underwater equipment and the object under test based on the multibeam slant range data collected by the forward multibeam sonar equipment includes: A temporary reference plane is constructed based on effective beam slant range data and historical attitude normal vectors; Calculate the actual vertical distance from the center of the underwater equipment to the temporary reference plane based on the temporary reference plane; Based on the difference between the actual vertical distance and the preset vertical distance, the position of the underwater equipment is adjusted in real time to maintain the preset vertical distance unchanged; The effective beam slant range data refers to the beam slant range data projected onto the observation surface after the switch, and the historical attitude normal vector refers to the attitude normal vector corresponding to the original observation surface retained before the observation surface switch.

6. The method according to claim 1, characterized in that, Before performing spatial coordinate transformation on the preset navigation path based on the spatial attitude of the switched observation surface, the method further includes: The pitch attitude of the underwater device is corrected based on the multibeam slant range data so that the underwater device is facing the switched observation surface. The angle formed by the underwater device relative to the horizontal reference attitude is taken as the final pitch angle.

7. The method according to claim 6, characterized in that, The step of performing spatial coordinate transformation on the preset navigation path based on the spatial attitude of the observed surface after switching includes: Construct a rotation matrix based on the final pitch angle; Based on the rotation matrix, the coordinates in the preset navigation path are spatially rotated and transformed to obtain the transformed navigation path; The converted navigation path retains at least some of the operating parameters of the preset navigation path unchanged.

8. The method according to claim 1, characterized in that, The step of enabling the underwater equipment to continue performing automatic ranging observations along the converted navigation path includes: The plane equation of the observation surface after switching is obtained by fitting the multibeam slant range data; The actual vertical distance from the center of the underwater equipment to the switched observation surface is calculated based on the plane equation. Based on the difference between the actual vertical distance and the preset vertical distance, the position of the underwater device is adjusted in real time to maintain the preset vertical distance unchanged.

9. An underwater device, characterized in that, The underwater device includes: a memory, a processor, and a control program for the underwater device stored in the memory and executable on the processor, the control program being configured to implement the steps of the distance observation method as described in any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a control program for an underwater device, which, when executed by a processor, implements the steps of the distance observation method as described in any one of claims 1 to 8.

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