Method for analyzing flow field during underwater robot arm movement

Abstract

The application provides a flow field analysis method in underwater mechanical arm movement process, the method comprises the following steps: determining the simulation movement parameter sequence of the mechanical arm in the underwater space, the simulation movement parameter sequence comprises a plurality of simulation movement parameters arranged in time sequence; based on the simulation movement parameter sequence, determining the first coordinate parameter sequence of the target part of the mechanical arm and the second coordinate parameter sequence of the dynamic plane slice corresponding to the target part of the mechanical arm, the dynamic plane slice matches the cross section where the target part is located, the first coordinate parameter sequence comprises a plurality of first coordinate parameters arranged in time sequence, the first coordinate parameter comprises the position point coordinates of a plurality of position points on the outer surface of the target part, and the second coordinate parameter sequence comprises a plurality of second coordinate parameters arranged in time sequence; based on the first coordinate parameter sequence, the second coordinate parameter sequence and the flow field data of the underwater space, the target part of the mechanical arm is subjected to flow field analysis, and the flow field analysis result of the target part is obtained.

Description

Technical Field

[0001] This application relates to the field of underwater robot fluid dynamics analysis and simulation post-processing technology, and in particular to a flow field analysis method for the movement of an underwater robotic arm. Background Technology

[0002] Underwater robotic arms are subjected to complex hydrodynamic forces during operation, including drag, additional mass forces, and unsteady forces caused by vortex shedding. Composed of multiple links and joints, the movement of a robotic arm involves a combination of relative rotation and translation between adjacent links, resulting in multi-mode fluid flow phenomena. Multiple arms interfere with each other at different attitudes, and the constantly changing attitude of the underwater robotic arm during operation causes significant variations in the instantaneous hydrodynamic coefficients over time. When vortex shedding occurs during underwater movement, its wake region becomes unstable. These factors all increase the difficulty of force analysis and control during the movement of the underwater robotic arm.

[0003] In the hydrodynamic analysis of underwater robotic arms, computer simulations are currently commonly used to obtain hydrodynamic parameters for various postures of the robotic arm. However, post-processing of the simulation results still faces many challenges. On the one hand, the amount of data output by the simulation is large, and existing post-processing tools struggle to directly extract certain key information; on the other hand, if the robotic arm or blunt body is in motion, its reference frame changes continuously relative to the flow field, making it difficult for traditional post-processing to easily obtain the flow field characteristics relative to the moving object. Currently, there is no perfect solution for efficient post-processing of the flow field of such underwater multi-motion-mode robotic arms, making it difficult to meet the need for rapid analysis of flow field characteristics under complex working conditions. Summary of the Invention

[0004] In view of this, this application provides a flow field analysis method during the movement of a robotic arm.

[0005] The flow field analysis method for the underwater robotic arm movement process provided in this application includes: determining a simulated motion parameter sequence of the robotic arm in underwater space, wherein the simulated motion parameter sequence includes multiple simulated motion parameters arranged in time sequence; based on the simulated motion parameter sequence, determining a first coordinate parameter sequence of the target part of the robotic arm and a second coordinate parameter sequence of a dynamic planar slice corresponding to the target part of the robotic arm, wherein the dynamic planar slice matches the cross section where the target part is located, the first coordinate parameter sequence includes multiple first coordinate parameters arranged in time sequence, the first coordinate parameters include the coordinates of multiple position points on the outer surface of the target part, the second coordinate parameter sequence includes multiple second coordinate parameters arranged in time sequence, the second coordinate parameters include the coordinates of multiple position points on the dynamic planar slice; and performing flow field analysis on the target part of the robotic arm based on the first coordinate parameter sequence, the second coordinate parameter sequence, and the flow field data of the underwater space to obtain the flow field analysis result of the target part.

[0006] According to an embodiment of this application, determining the second coordinate parameter sequence of a dynamic planar slice corresponding to a target part of a robotic arm based on a simulated motion parameter sequence includes: determining a control function for the pose of the dynamic planar slice changing over time based on the simulated motion parameter sequence, wherein the pose includes at least one of the position and angle of the dynamic planar slice; determining the second coordinate parameters of the pose of the dynamic planar slice at any time step based on the control function; and determining the second coordinate parameter sequence based on the second coordinate parameters of the poses of the dynamic planar slice at multiple time steps.

[0007] According to an embodiment of this application, determining a first coordinate parameter sequence of a target part of a robotic arm and a second coordinate parameter sequence of a dynamic planar slice corresponding to the target part of the robotic arm based on a simulated motion parameter sequence includes: determining a first coordinate parameter sequence of a target part of the robotic arm based on a simulated motion parameter sequence; determining the initial second coordinate parameters of the dynamic planar slice when the robotic arm is in the initial motion position, and the relative positional relationship between the dynamic planar slice and the target part at the initial motion position; and updating the initial second coordinate parameters at multiple time steps based on the first coordinate parameter sequence and the relative positional relationship to obtain the second coordinate parameter sequence.

[0008] According to an embodiment of this application, flow field analysis is performed on the target part of the robotic arm based on a first coordinate parameter sequence, a second coordinate parameter sequence, and flow field data of the underwater space to obtain the flow field analysis result of the target part. This includes: determining the flow field data of the target space from the flow field data of the underwater space based on the first coordinate parameter sequence and the second coordinate parameter sequence, wherein the target space is the space between the outer surface of the target part and the edge of the dynamic planar slice; and performing flow field analysis on the target part of the robotic arm based on the flow field data of the target space to obtain the flow field analysis result of the target part.

[0009] According to an embodiment of this application, the flow field data includes pressure field data and velocity field data; based on the flow field data of the target space, flow field analysis is performed on the target part of the robotic arm to obtain the flow field analysis result of the target part, including: based on the pressure field data and velocity field data of the target space, the resultant force of the pressure and the additional mass force on the target part is integrated to obtain the total resultant force of the target part; based on the total resultant force, the flow field analysis result of the target part is obtained.

[0010] According to an embodiment of this application, the flow field data further includes vorticity field data; based on the total resultant force, the flow field analysis results of the target part are obtained, including: based on the vorticity field data of the target space, calculating the unsteady force caused by vortex shedding generated by the underwater simulated motion of the robotic arm at the target part, and obtaining the unsteady force at the target part; based on the total resultant force and the unsteady force, the flow field analysis results of the target part are obtained.

[0011] According to an embodiment of this application, one end of the robotic arm is fixed to a base, and the robotic arm can move around the base. Multiple dynamic planar slices divide the robotic arm into multiple robotic arm segments. The method further includes: determining the total resultant force of each of the multiple robotic arm segments based on the flow field data of the space where each of the multiple robotic arm segments is located; and determining the torque of each of the multiple robotic arm segments relative to the base based on the total resultant force of each of the multiple robotic arm segments and the distances of each of the multiple robotic arm segments from the base.

[0012] According to an embodiment of this application, the method further includes: the robotic arm includes a first arm connected to a base and a second arm connected to the first arm via a joint; the method further includes: determining the relative position information of the joint relative to the base; based on the torques of the multiple robotic arm segments of the second arm relative to the base and the relative position information of the joint relative to the base, converting the torques of the multiple robotic arm segments of the second arm relative to the base into torques of the multiple robotic arm segments of the second arm relative to the joint.

[0013] According to an embodiment of this application, the method further includes: determining a first space for characterizing the wake region formed by the robotic arm during underwater simulated motion based on the range of motion of the robotic arm; dividing the first space into a grid using a first grid size to obtain a grid of a first size; dividing the second space into a grid using a second grid size to obtain a grid of a second size, wherein the second space is the space in the underwater space other than the first space, the first grid size is smaller than the second grid size, and the grid is used to calculate the flow field data at the corresponding position during the simulated motion of the robotic arm in the underwater space.

[0014] Another aspect of this application provides an electronic device, comprising: one or more processors; and a memory for storing one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors cause the one or more processors to implement the method described above.

[0015] According to the embodiments of this application, the first coordinate parameter sequence of the target part and the second coordinate parameter sequence of the dynamic planar slice are determined by the simulated motion parameter sequence of the robotic arm in the underwater space. The flow field analysis of the target part is then performed in combination with the flow field data. Since the dynamic planar slice and the cross section of the target part of the robotic arm are always matched, the interaction interface between the robotic arm and the flow field under different motion postures can be accurately characterized by the dynamic planar slice. This allows for convenient and accurate capture of the local flow field characteristics of the target part at any time step, which facilitates efficient and rapid flow field analysis processing of the robotic arm in the future. Attached Figure Description

[0016] The above-mentioned contents, other objects, features and advantages of this application will become clearer from the following description of embodiments of this application with reference to the accompanying drawings.

[0017] Figure 1 A flowchart of a flow field analysis method for an underwater robotic arm during its movement, according to an embodiment of this application, is shown.

[0018] Figure 2 A schematic diagram showing the effect of meshing the first and second regions according to an embodiment of this application is provided.

[0019] Figure 3 A schematic diagram of the flow field distribution around the robotic arm during its motion, according to an embodiment of this application, is shown.

[0020] Figure 4 A dynamic planar slice of the robotic arm during its movement according to an embodiment of this application is shown.

[0021] Figure 5 The diagram shows the effect of multiple dynamic planar flow field distributions according to embodiments of this application.

[0022] Figure 6 A block diagram of an electronic device suitable for implementing a flow field analysis method for underwater robotic arm movement, according to an embodiment of this application, is shown. Detailed Implementation

[0023] The embodiments of this application will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of this application. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of this application for ease of explanation. However, it will be apparent that one or more embodiments may be implemented without these specific details. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this application.

[0024] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The terms “comprising,” “including,” etc., as used herein indicate the presence of features, steps, operations, and / or first components, but do not exclude the presence or addition of one or more other features, steps, operations, or first components.

[0025] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0026] When using expressions such as "at least one of A, B and C", they should generally be interpreted in accordance with the meaning that is commonly understood by those skilled in the art (e.g., "a system having at least one of A, B and C" should include, but is not limited to, a system having A alone, a system having B alone, a system having C alone, a system having A and B, a system having A and C, a system having B and C, and / or a system having A, B and C, etc.).

[0027] Figure 1 A flowchart of a flow field analysis method for an underwater robotic arm during its movement, according to an embodiment of this application, is shown.

[0028] like Figure 1 As shown, the method includes steps S110 to S130.

[0029] In step S110, the sequence of simulated motion parameters of the robotic arm in the underwater space is determined, wherein the sequence of simulated motion parameters includes multiple simulated motion parameters arranged in time sequence.

[0030] In step S120, based on the simulated motion parameter sequence, the first coordinate parameter sequence of the target part of the robotic arm and the second coordinate parameter sequence of the dynamic planar slice corresponding to the target part of the robotic arm are determined.

[0031] The dynamic plane slice is matched with the cross section where the target part is located. The first coordinate parameter sequence includes multiple first coordinate parameters arranged in time sequence. The first coordinate parameters include the coordinates of multiple position points on the outer surface of the target part. The second coordinate parameter sequence includes multiple second coordinate parameters arranged in time sequence. The second coordinate parameters include the coordinates of multiple position points on the dynamic plane slice.

[0032] In step S130, based on the first coordinate parameter sequence, the second coordinate parameter sequence, and the flow field data of the underwater space, the flow field analysis of the target part of the robotic arm is performed to obtain the flow field analysis results of the target part.

[0033] Multiple simulation motion parameters include the robot arm's velocity, acceleration, angular velocity, and direction of motion at any given time step. Based on these simulation motion parameters, the robot arm's position at any given time step can be determined.

[0034] For example, to perform flow field analysis on different motion modes of a robotic arm, the acceleration, constant speed, and deceleration motions of the robotic arm can be simulated separately. For instance, starting from rest, the upper and lower arms can swing to a target angle with a certain angular acceleration (acceleration phase), then maintain a constant angular velocity for a period of time (constant speed phase), and finally decelerate to a stop with reverse acceleration (deceleration phase). The flow field data for each time step under each motion state can then be calculated using computer simulation software.

[0035] Flow field data reflects the distribution and changes of physical quantities such as velocity, pressure, and vorticity under the interaction between the fluid and the robotic arm. Computational Fluid Dynamics (CFD) can be used to numerically simulate the motion of the robotic arm underwater and obtain flow field data.

[0036] For example, a dynamic planar slice perpendicular to the robotic arm can be set at the target location of the robotic arm. Based on the simulated motion parameter sequence of the robotic arm, the dynamic planar slice can move synchronously with the robotic arm. Specifically, the center position of the cross-section where the target location is located can be aligned with the dynamic planar slice, and the position and angle of the cross-section where the target location is located can be aligned with the position and angle of the dynamic slice, thereby matching the position of the cross-section where the target location of the robotic arm is located with that of the dynamic planar slice. Because the dynamic planar slice matches the cross-section where the target location of the robotic arm in real time, the evolution of the flow field around the target location as it moves can be dynamically extracted using the dynamic planar slice.

[0037] The first set of coordinate parameters provides the surface position of the target area of ​​the robotic arm, defining the boundary of the force application. The second set of coordinate parameters provides the spatial information of the flow field corresponding to the target area of ​​the robotic arm.

[0038] Based on the first coordinate parameter sequence, the second coordinate parameter sequence, and the flow field data in the underwater space, the force on the target part can be integrated to obtain the flow field analysis results of the target part.

[0039] According to the embodiments of this application, the first coordinate parameter sequence of the target part and the second coordinate parameter sequence of the dynamic planar slice are determined by the simulated motion parameter sequence of the robotic arm in the underwater space. The flow field analysis of the target part is then performed in combination with the flow field data. Since the dynamic planar slice and the cross section of the target part of the robotic arm are always matched, the interaction interface between the robotic arm and the flow field under different motion postures can be accurately characterized by the dynamic planar slice. This allows for convenient and accurate capture of the local flow field characteristics of the target part at any time step, which facilitates efficient and rapid flow field analysis processing of the robotic arm in the future.

[0040] According to an embodiment of this application, before performing underwater simulation motion on the robotic arm, the method may further include: determining a first space formed by the robotic arm during the underwater simulation motion to characterize the wake region, based on the range of motion of the robotic arm; dividing the first space into a grid using a first grid size to obtain a grid of a first size; dividing a second space into a grid using a second grid size to obtain a grid of a second size, wherein the second space is the underwater space excluding the first space, the first grid size is smaller than the second grid size, and the grid is used to calculate the flow field data at corresponding positions during the simulated motion of the robotic arm in the underwater space.

[0041] Because of the wake region formed by the robotic arm during its movement, this application can cover the expected wake region by pre-designing an irregularly shaped computational domain to obtain a first region. Specifically, the shape of the computational domain containing the complete wake development region can be sculpted according to the robotic arm's motion trajectory using 3D modeling software, and combined with a standard flow field domain, enabling mesh generation software to recognize and generate a mesh of this complex shape.

[0042] The first region, which contains the critical wake region, can be locally refined using the first grid size, and the second region can be coarsely divided using the second grid size. Then, the fine grid region and the coarser grid region can be merged to ensure a smooth grid transition and avoid possible parsing errors when dividing directly on the overall complex region.

[0043] Figure 2 A schematic diagram showing the effect of meshing the first and second regions according to an embodiment of this application is provided.

[0044] like Figure 2 As shown, the first region 201 is divided into smaller, more detailed grids to allow for more accurate calculations of the flow field data in the wake region. The second region 202 is divided into larger grids to reduce computational load.

[0045] According to embodiments of this application, by applying a fine mesh to the wake region of the joint and a coarse mesh to the remaining region, the number of invalid mesh elements can be reduced while ensuring the capture of vortex shedding and wake details, thereby reducing the computational load. Thus, the simulation can run more efficiently while maintaining accuracy.

[0046] According to embodiments of this application, determining the second coordinate parameter sequence of a dynamic planar slice corresponding to a target part of a robotic arm based on a simulated motion parameter sequence may include: determining a control function for the pose of the dynamic planar slice changing over time based on the simulated motion parameter sequence, wherein the pose includes at least one of the position and angle of the dynamic planar slice; determining the second coordinate parameters of the pose of the dynamic planar slice at any time step based on the control function; and determining a second coordinate parameter sequence based on the second coordinate parameters of the poses of the dynamic planar slice at multiple time steps.

[0047] For example, when the robotic arm performs translational motion, a control function for the position of the dynamic planar slice changing over time can be determined based on the simulated motion parameter sequence of the robotic arm. When the robotic arm rotates, a control function for the rotation angle of the dynamic planar slice changing over time can be determined. When the robotic arm performs both translational and rotational motions simultaneously, control functions for the position and angle of the dynamic planar slice changing over time can be determined.

[0048] Specifically, the instantaneous rotation angle or position of the robotic arm at each time step can be read, the angle of the dynamic plane slice can be set to that rotation angle value, the center of the dynamic plane slice can be located at the geometric center of the target part section, and the position coordinates of multiple current position points of the dynamic plane slice can be read to obtain the second coordinate parameter.

[0049] It can traverse all time steps of the simulation process, and arrange and combine the slice poses obtained at each time step in chronological order to obtain a complete sequence of second coordinate parameters.

[0050] By establishing a pose control function for dynamic planar slices, continuous and precise parametric control of the slice pose over time was achieved. This ensures that the dynamic planar slices always maintain synchronous matching with the cross-sectional motion of the target part of the robotic arm, thereby efficiently generating a temporally continuous and spatially accurate sequence of second coordinate parameters. This not only improves the computational efficiency and stability of the flow field coupling simulation but also guarantees the spatiotemporal consistency of the geometric representation in the flow field analysis, providing a reliable geometric motion foundation for subsequent refined flow field analysis.

[0051] According to an embodiment of this application, determining a first coordinate parameter sequence of the target part of the robotic arm and a second coordinate parameter sequence of the dynamic planar slice corresponding to the target part of the robotic arm based on a simulated motion parameter sequence may include: determining a first coordinate parameter sequence of the target part of the robotic arm based on a simulated motion parameter sequence; determining the initial second coordinate parameters of the dynamic planar slice when the robotic arm is in the initial motion position, and the relative positional relationship between the dynamic planar slice and the target part at the initial motion position; and updating the initial second coordinate parameters at multiple time steps based on the first coordinate parameter sequence and the relative positional relationship to obtain the second coordinate parameter sequence.

[0052] For example, a global coordinate system can be established in the underwater space, the first coordinate parameters of the target part in the global coordinate system at any time step can be read, and the first coordinate parameter sequence can be obtained based on the first coordinate parameters of all time steps in the global coordinate system.

[0053] For example, an initial second coordinate parameter can be determined based on the first coordinate parameter of the robotic arm at the starting position, and the relative position of the first coordinate parameter and the second coordinate parameter can be determined.

[0054] For example, a local coordinate system containing the target part can be defined, in which the third coordinate parameter of the target part and the fourth coordinate parameter of the dynamic planar slice can be determined, and the local coordinate system can be made to move synchronously with the robotic arm. The relative positional relationship between the dynamic planar slice and the target part can be determined based on the third and fourth coordinate parameters.

[0055] For example, the initial second coordinate parameters can be transformed at multiple time steps based on the first coordinate parameter sequence and the relative position relationship to obtain the second coordinate parameter sequence.

[0056] Dynamic planar slice tracking can be used to observe the flow field around the cross section of the robotic arm itself, and also to study the influence of the robotic arm's motion on specific regions of the surrounding flow field.

[0057] Based on the second coordinate parameter sequence, a series of multiple slice images can be derived. Based on the multiple slice images, a slice animation can be synthesized. Thus, based on the distribution of flow field data on the multiple slice images, the formation, shedding, and evolution of the wake vortex street behind the robotic arm during the motion process can be obtained.

[0058] Figure 3 A schematic diagram of the flow field distribution around the robotic arm during its motion, according to an embodiment of this application, is shown.

[0059] like Figure 3 As shown, during the simulated underwater motion of the robotic arm, the flow field distribution around the robotic arm can be simulated through simulation calculation. A dynamic plane slice perpendicular to the robotic arm can be set at the target part 301 of the robotic arm, and the flow field data around the target part 301 can be obtained by using the dynamic plane slice.

[0060] According to an embodiment of this application, based on a first coordinate parameter sequence, a second coordinate parameter sequence, and underwater flow field data, flow field analysis is performed on the target part of the robotic arm to obtain the flow field analysis result of the target part. This can include: determining the flow field data of the target space from the underwater flow field data based on the first coordinate parameter sequence and the second coordinate parameter sequence, wherein the target space is the space between the outer surface of the target part and the edge of the dynamic planar slice; and performing flow field analysis on the target part of the robotic arm based on the flow field data of the target space to obtain the flow field analysis result of the target part.

[0061] For example, the edge of the dynamic planar slice characterizes the boundary of the flow field, and the target space from the outer surface of the target part to the flow field boundary can be determined based on the first coordinate parameter sequence and the second coordinate parameter sequence.

[0062] The flow field data at each location in the target space can be determined based on the grid corresponding to each location. Based on the flow field data at each location in the target space, flow field analysis is performed on the target area to obtain the flow field analysis results.

[0063] Figure 4 A dynamic planar slice of the robotic arm during its movement according to an embodiment of this application is shown.

[0064] like Figure 4As shown, flow field data at corresponding locations can be read from each grid of a dynamic planar slice. By utilizing the flow field data at each location, flow field analysis can be performed on the target area to obtain the flow field analysis results for the target area.

[0065] According to embodiments of this application, the flow field data includes pressure field data and velocity field data. Based on the flow field data of the target space, flow field analysis is performed on the target part of the robotic arm to obtain the flow field analysis results of the target part, which may include: based on the pressure field data and velocity field data of the target space, the resultant force of the pressure and the additional mass force acting on the target part is integrated to obtain the total resultant force of the target part; based on the total resultant force, the flow field analysis results of the target part are obtained.

[0066] The pressure field data includes the water pressure perpendicular to the surface at various points on the surface of the robotic arm during its movement in water. The velocity field data includes fluid velocity, acceleration, and other data. When the robotic arm accelerates, it needs to push the fluid in front of it to also accelerate. According to Newton's third law, the fluid will exert a reverse inertial drag on the object, which is the additional mass force.

[0067] The resultant force of the pressure and additional mass forces of each grid corresponding to the target space can be multiplied by the tiny area element at that point to obtain the resultant force vector perpendicular to the surface. The total resultant force is obtained by vector integration of all resultant force vectors in the target space.

[0068] According to embodiments of this application, the flow field data further includes vorticity field data. Based on the total resultant force, obtaining the flow field analysis results for the target location may include: calculating the unsteady force caused by vortex shedding generated by the underwater simulated motion of the robotic arm at the target location based on the vorticity field data of the target space, thereby obtaining the unsteady force at the target location; and obtaining the flow field analysis results for the target location based on the total resultant force and the unsteady force.

[0069] Eddy field data describes the intensity and direction of the rotation of fluid particles in space. Eddy shedding refers to the phenomenon where, as fluid flows around an object (such as a robotic arm), eddies form on or behind the object and detach with the flow of the fluid. Eddy shedding causes periodic changes in fluid pressure, thereby generating unsteady forces on the target area and affecting its stress state and vibration characteristics.

[0070] For example, based on vorticity field data and the robotic arm's motion parameters (such as velocity and attitude), the unsteady force caused by vortex shedding at the target location can be calculated using fluid dynamics principles or related models. The time history data of the unsteady force can be used, combined with the robotic arm's dynamic model or vibration theory, to calculate the vibration response of the target location. Vibration amplitude information can then be extracted from the vibration response.

[0071] Vibrations caused by unsteady forces can lead to fatigue damage to the materials of robotic arms, reducing their service life. Studies of vibration amplitude can help predict the durability of robotic arms during long-term use, providing a reference for determining maintenance and replacement cycles.

[0072] According to embodiments of this application, the target parts include multiple parts, and each target part corresponds one-to-one with a multiple dynamic planar slice. The method may further include: performing flow field analysis on the multiple target parts of the robotic arm based on a first coordinate parameter sequence for each of the multiple target parts, a second coordinate parameter sequence for each of the multiple dynamic planar slices, and flow field data of the underwater space, to obtain flow field analysis results for each of the multiple target parts.

[0073] For example, multiple target locations can be defined on the surface of the robotic arm at fixed intervals, and dynamic planar slices perpendicular to the robotic arm can be set at each of the multiple target locations to extract local flow field data of the target locations. Each dynamic planar slice corresponds to a target location, and its position and orientation are dynamically adjusted as the robotic arm moves.

[0074] Based on multiple dynamic planar slices, the flow field distribution of different parts of the robotic arm at different time steps can be visualized and observed. It is also possible to observe the impact of the robotic arm's movement on specific areas of the surrounding flow field.

[0075] For example, during the acceleration phase, the rapid start of the robotic arm causes a rapid increase in the vortex volume in the wake region, and the slice shows that the vortex symmetry is broken and the distribution is asymmetrical; during the constant speed phase, the slice shows that the wake vortex shedding frequency tends to stabilize, forming a more regular KAMAN vortex street structure; during the deceleration phase, the vortex street spacing changes and vortex merging occurs.

[0076] By mapping multiple target parts to multiple dynamic planar slices one by one, and using the first coordinate parameter sequence, the second coordinate parameter sequence and underwater flow field data to perform flow field analysis, the flow field distribution characteristics of different parts of the robotic arm in a complex underwater environment can be dynamically captured.

[0077] Figure 5 The diagram shows the effect of multiple dynamic planar flow field distributions according to embodiments of this application.

[0078] like Figure 5 As shown, by setting multiple dynamic planar slices 502 on multiple target parts of the robotic arm 501, the flow field distribution of different parts of the robotic arm during movement can be dynamically observed through these dynamic planar slices 502. This provides great convenience for visually studying the flow field evolution of different parts of the robotic arm during movement.

[0079] According to an embodiment of this application, one end of the robotic arm is fixed to a base, and the robotic arm can move around the base. Multiple dynamic planar slices divide the robotic arm into multiple robotic arm segments. The method may further include: determining the total resultant force of each of the multiple robotic arm segments based on flow field data of the space in which each of the multiple robotic arm segments is located; and determining the torque of each of the multiple robotic arm segments relative to the base based on the total resultant force of each of the multiple robotic arm segments and the distances of each of the multiple robotic arm segments from the base.

[0080] Based on the pressure and velocity field data of the space where the robotic arm segment is located, the resultant force of the pressure and additional mass force received by the robotic arm segment can be integrated to obtain the total resultant force of the robotic arm segment. Then, the torque of the robotic arm segment relative to the base can be obtained by multiplying the total resultant force by the distance between the robotic arm and the base.

[0081] By measuring the torques of multiple robotic arm segments relative to the base, the torque distribution pattern of different parts of the robotic arm can be determined.

[0082] According to an embodiment of this application, when the robotic arm includes a first arm connected to a base and a second arm connected to the first arm via a joint, the method may further include: determining the relative position information of the joint relative to the base; and based on the torques of the multiple robotic arm segments of the second arm relative to the base and the relative position information of the joint relative to the base, converting the torques of the multiple robotic arm segments of the second arm relative to the base into torques of the multiple robotic arm segments of the second arm relative to the joint.

[0083] For example, the torque of the robotic arm segment of the second arm relative to the base is set to M. o The resultant force on the second arm's robotic arm segment is F, the vector distance between the joint and the base is r, and the torque M of the second arm's robotic arm segment relative to the joint is given by formula (1).

[0084] (1).

[0085] In three-dimensional space, the torque can be decomposed into components in three directions: x-axis, y-axis, and z-axis. Each component is summed and then synthesized to obtain the magnitude and direction of the torque of the relatively critical segment of the robotic arm.

[0086] In a robotic arm comprising a first arm connected to a base and a second arm connected to the first arm via joints, by converting the torque of the second arm's robotic arm segment relative to the base into a torque relative to the joints, the coordinated motion control of the robotic arm can be guided based on the torque distribution of the first arm relative to the base and the torque distribution of the second arm relative to the joints. This allows the movements of each arm to be staggered from the most severe fluid disturbance zones, thereby reducing the impact torque on the base and joints.

[0087] For example, multiple arms can be provided that are connected sequentially by joints, and the torque of each arm relative to its respective joint can be determined in the same manner as the second arm.

[0088] In some cases, computer simulation software can directly output the torque of the robotic arm relative to the base, but the resultant force of the robotic arm is unknown. In such cases, it is impossible to directly convert the torque of the robotic arm relative to the base into the torque of the robotic arm relative to the joint. Therefore, the embodiments of this application can convert the torque of the robotic arm relative to the base into the torque at any point in space by setting auxiliary analysis points.

[0089] Specifically, the base can be used as the origin O=(0,0,0), and three additional auxiliary reference points P can be selected on the same surface set and in the same coordinate system. x =(d,0,0), P y =(0,d,0) and P z =(0,0,d), where d is a value greater than 0, and d can represent the distance between the auxiliary reference point and the origin. This obtains the torque of the robotic arm segment relative to the base and the auxiliary reference point at the same moment. For example, the torque at the origin O is set to M. o Auxiliary reference point P x The torque relative to the origin O is M x Auxiliary reference point P y The torque relative to the origin O is M y Auxiliary reference point P z The torque relative to the origin O is M z Then, the torque increment of each auxiliary reference point relative to the base can be calculated, see formula (2):

[0090] , , (2);

[0091] in, Indicates auxiliary reference point P x The torque increment relative to the base, Indicates auxiliary reference point P y The torque increment relative to the base, Indicates auxiliary reference point P z The torque increment relative to the base.

[0092] Therefore, three sets of linear relationship formulas can be obtained, see formulas (3) to (5):

[0093] (3);

[0094] (4);

[0095] (5);

[0096] Where F represents the resultant force, , and This represents the component forces of the resultant force F in the X, Y, and Z axes.

[0097] Treating the nine scalar equations of the three sets of linear relationship formulas above as an overdetermined system, and using a robust closed-form solution with symmetric averaging, we can obtain the components of the resultant force F in the X, Y, and Z axes. , and The expression is given in formulas (6) to (8):

[0098] (6);

[0099] (7);

[0100] (8);

[0101] in,( ) x 、( ) y and( ) z These represent the torque increments of the auxiliary reference point relative to the base. , and Components on the X, Y, and Z axes.

[0102] Set the joint's position coordinates as r=(a,b,c) T Then the torque of the robotic arm segment relative to the joint See formula (9) for the expression:

[0103] (9);

[0104] in, , and The torque of the robotic arm segment relative to the base is... Components on the X, Y, and Z axes.

[0105] Therefore, even when the resultant force of the robotic arm segment is unknown, the resultant force can be deduced by using multiple auxiliary reference points, thereby converting the torque of the robotic arm relative to the base into the torque of the relative joint.

[0106] Figure 6 A block diagram of an electronic device suitable for implementing a flow field analysis method for underwater robotic arm movement, according to an embodiment of this application, is shown.

[0107] Figure 6The electronic device shown is merely an example and should not impose any limitation on the functionality and scope of use of the embodiments of this application.

[0108] Electronic devices are intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. Electronic devices can also represent various forms of mobile devices, such as personal digital processors, cellular phones, smartphones, wearable devices, and other similar computing devices. The first components shown herein, their connections and relationships, and their functions are merely illustrative and are not intended to limit the implementation of the present application described and / or claimed herein.

[0109] like Figure 6 As shown, the electronic device 600 includes a computing unit 601, which can perform various appropriate actions and processes based on a computer program stored in a read-only memory (ROM) 602 or a computer program loaded from a storage unit 608 into a random access memory (RAM) 603. The RAM 603 may also store various programs and data required for the operation of the electronic device 600. The computing unit 601, ROM 602, and RAM 603 are interconnected via a bus 604. An input / output (I / O) interface 605 is also connected to the bus 604.

[0110] Multiple first components in electronic device 600 are connected to I / O interface 605, including: input unit 606, such as keyboard, mouse, etc.; output unit 607, such as various types of displays, speakers, etc.; storage unit 608, such as disk, optical disk, etc.; and communication unit 609, such as network card, modem, wireless transceiver, etc. Communication unit 609 allows electronic device 600 to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks.

[0111] The computing unit 601 can be a variety of general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of the computing unit 601 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various special-purpose artificial intelligence (AI) computing chips, various computing units running machine learning model algorithms, a digital signal processor (DSP), and any suitable processor, controller, microcontroller, etc. The computing unit 601 performs the various methods and processes described above. For example, in some embodiments, the flow field analysis method during the movement of an underwater robotic arm can be implemented as a computer software program, which is tangibly contained in a machine-readable medium, such as storage unit 608. In some embodiments, part or all of the computer program can be loaded and / or installed on the electronic device 600 via ROM 602 and / or communication unit 609. When the computer program is loaded into RAM 603 and executed by the computing unit 601, one or more steps of the methods described above can be performed. Alternatively, in other embodiments, the computing unit 601 can be configured to perform the methods described above by any other suitable means (e.g., by means of firmware).

[0112] Various embodiments of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), systems-on-a-chip (SoCs), complex programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments may include implementations in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which may be a dedicated or general-purpose programmable processor, capable of receiving data and instructions from a storage system, at least one input device, and at least one output device, and transmitting data and instructions to the storage system, the at least one input device, and the at least one output device.

[0113] The program code used to implement the methods of this application may be written in any combination of one or more programming languages. This program code may be provided to the processor or controller of a general-purpose computer, special-purpose computer, or other programmable test apparatus, such that when executed by the processor or controller, the functions / operations specified in the flowcharts and / or block diagrams are implemented. The program code may be executed entirely on a machine, partially on a machine, as a standalone software package partially on a machine and partially on a remote machine, or entirely on a remote machine or server.

[0114] In the context of this application, a machine-readable medium can be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, apparatus, or device. A machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. Machine-readable media can be, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0115] To provide interaction with a user, the systems and techniques described herein can be implemented on a computer having: a display device for displaying information to the user (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor); and a keyboard and pointing device (e.g., a mouse or trackball) through which the user provides input to the computer. Other types of devices can also be used to provide interaction with the user; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including sound input, voice input, or tactile input).

[0116] The systems and technologies described herein can be implemented in computing systems that include a back-end first component (e.g., as a data server), or a computing system that includes a middleware first component (e.g., an application server), or a computing system that includes a front-end first component (e.g., a user computer with a graphical user interface or web browser through which a user can interact with embodiments of the systems and technologies described herein), or any combination of such a back-end first component, middleware first component, or front-end first component. The first components of the system can be interconnected via digital data communication (e.g., a communication network) of any form or medium. Examples of communication networks include local area networks (LANs), wide area networks (WANs), and the Internet.

[0117] Computer systems can include clients and servers. Clients and servers are generally located far apart and typically interact via communication networks. Client-server relationships are created by computer programs running on the respective computers and having a client-server relationship with each other. Servers can be cloud servers, distributed system servers, or servers incorporating blockchain technology.

[0118] Those skilled in the art will understand that the features described in the various embodiments of this application can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in this application. In particular, the features described in the various embodiments of this application can be combined and / or combined in various ways without departing from the spirit and teachings of this application. All such combinations and / or combinations fall within the scope of this application.

[0119] The embodiments of this application have been described above. However, these embodiments are merely illustrative and not intended to limit the scope of this application. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. Without departing from the scope of this application, those skilled in the art can make various substitutions and modifications, all of which should fall within the scope of this application.

Claims

1. A method for analyzing the flow field during the movement of an underwater robotic arm, characterized in that, The method includes: Determine the sequence of simulated motion parameters for the robotic arm in underwater space, wherein the sequence of simulated motion parameters includes multiple simulated motion parameters arranged in chronological order; Based on the simulated motion parameter sequence, a first coordinate parameter sequence of the target part of the robotic arm and a second coordinate parameter sequence of the dynamic planar slice corresponding to the target part of the robotic arm are determined. The dynamic planar slice matches the cross section where the target part is located. The first coordinate parameter sequence includes multiple first coordinate parameters arranged in time sequence. The first coordinate parameters include the coordinates of multiple position points on the outer surface of the target part. The second coordinate parameter sequence includes multiple second coordinate parameters arranged in time sequence. The second coordinate parameters include the coordinates of multiple position points on the dynamic planar slice. Based on the first coordinate parameter sequence, the second coordinate parameter sequence, and the flow field data of the underwater space, flow field analysis is performed on the target part of the robotic arm to obtain the flow field analysis results of the target part.

2. The method according to claim 1, characterized in that, Based on the simulated motion parameter sequence, the second coordinate parameter sequence of the dynamic planar slice corresponding to the target part of the robotic arm is determined, including: Based on the simulated motion parameter sequence, a control function is determined to change the pose of the dynamic planar slice over time, wherein the pose includes at least one of the position and angle of the dynamic planar slice; Based on the control function, the second coordinate parameters of the dynamic planar slice at any time step pose are determined; The second coordinate parameter sequence is determined based on the second coordinate parameters of the pose of the dynamic planar slice at multiple time steps.

3. The method according to claim 1, characterized in that, Based on the simulated motion parameter sequence, the first coordinate parameter sequence of the target part of the robotic arm and the second coordinate parameter sequence of the dynamic planar slice corresponding to the target part of the robotic arm are determined, including: Based on the simulated motion parameter sequence, the first coordinate parameter sequence of the target part of the robotic arm is determined; Determine the initial second coordinate parameters of the dynamic planar slice when the robotic arm is in the initial movement position, and the relative positional relationship between the dynamic planar slice and the target part in the initial movement position; Based on the first coordinate parameter sequence and the relative position relationship, the initial second coordinate parameters are updated at multiple time steps to obtain the second coordinate parameter sequence.

4. The method according to claim 1, characterized in that, Based on the first coordinate parameter sequence, the second coordinate parameter sequence, and the flow field data of the underwater space, a flow field analysis is performed on the target part of the robotic arm to obtain the flow field analysis results of the target part, including: Based on the first coordinate parameter sequence and the second coordinate parameter sequence, the flow field data of the target space is determined from the flow field data of the underwater space, wherein the target space is the space between the outer surface of the target part and the edge of the dynamic plane slice of the dynamic plane slice; Based on the flow field data of the target space, flow field analysis is performed on the target part of the robotic arm to obtain the flow field analysis results of the target part.

5. The method according to claim 4, characterized in that, The flow field data includes pressure field data and velocity field data; Based on the flow field data of the target space, flow field analysis is performed on the target part of the robotic arm to obtain the flow field analysis results of the target part, including: Based on the pressure field data and velocity field data of the target space, the resultant force of the pressure and the additional mass force on the target part is calculated by integration to obtain the total resultant force of the target part; Based on the resultant force, the flow field analysis results of the target location are obtained.

6. The method according to claim 5, characterized in that, The flow field data also includes vorticity field data; Based on the total resultant force, the flow field analysis results of the target location are obtained, including: Based on the vortex field data of the target space, the unsteady force caused by vortex shedding generated by the underwater simulated motion of the robotic arm at the target location is calculated to obtain the unsteady force at the target location. Based on the total resultant force and the unsteady force, the flow field analysis results of the target location are obtained.

7. The method according to any one of claims 1 to 6, characterized in that, The target part includes multiple parts, and each of the multiple target parts corresponds one-to-one with the multiple dynamic planar slices; The method further includes: Based on the first coordinate parameter sequence of each of the multiple target parts, the second coordinate parameter sequence of each of the multiple dynamic planar slices, and the flow field data of the underwater space, flow field analysis is performed on the multiple target parts of the robotic arm to obtain the flow field analysis results of each of the multiple target parts.

8. The method according to claim 7, characterized in that, One end of the robotic arm is fixed to the base, and the robotic arm can move around the base. Multiple dynamic planar slices divide the robotic arm into multiple robotic arm segments. The method further includes: Based on the flow field data of the space where each of the multiple robotic arm segments is located, the total resultant force of each of the multiple robotic arm segments is determined. Based on the total resultant force of each of the multiple robotic arm segments and the distances of each of the multiple robotic arm segments from the base, the torques of each of the multiple robotic arm segments relative to the base are determined.

9. The method according to claim 8, characterized in that, The robotic arm includes a first arm connected to a base and a second arm connected to the first arm via a joint; The method further includes: Determine the position information of the joint relative to the base; Based on the torques of the multiple robotic arm segments of the second arm relative to the base and the position information of the joints relative to the base, the torques of the multiple robotic arm segments of the second arm relative to the base are converted into torques of the multiple robotic arm segments of the second arm relative to the joints.

10. The method according to any one of claims 1 to 6, characterized in that, The method further includes: Based on the range of motion of the robotic arm, a first space for characterizing the wake region is determined during the underwater simulated motion of the robotic arm. The first space is divided into grids using the first grid size to obtain a grid of the first size; The second space is divided into grids using a second grid size to obtain a grid of the second size. The second space is the underwater space excluding the first space. The first grid size is smaller than the second grid size. The grid is used to calculate the flow field data at the corresponding position during the simulated motion of the robotic arm in the underwater space.

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