Closed-loop Motion Control Simulation Method and Device for Underwater Vehicle Integrated with CFD

Abstract

This application belongs to the field of motion control technology, and specifically discloses a closed-loop motion control simulation method and device for an underwater vehicle integrating CFD. According to the pose of the underwater vehicle at the previous moment, this application uses fluid dynamics theories such as the N-S equation to calculate the flow field forces and flow field torques applied to the vehicle at the current moment; combines the control forces and control torques required at the current moment calculated according to the pose deviation by the closed-loop control algorithm, and uses them as inputs to the six-degree-of-freedom motion equation of the vehicle to perform motion control simulation. This causes changes in the pose of the vehicle at the next moment, which will cause changes in the flow field, fluid forces, and pose deviation. Therefore, it is necessary to update the pose and perform iterative calculations until the pose deviation is within the preset range. This method realizes the accurate simulation and real-time feedback of the navigation motion of the underwater vehicle, significantly improves the control accuracy, is closer to the actual operation process, and provides important support for actual parameter tuning, verification of control methods, etc.

Description

Technical Field

[0001] This application belongs to the technical field of motion control, and more specifically, relates to a closed-loop motion control simulation method and device for an underwater vehicle integrating CFD. Background Art

[0002] Traditional motion control simulation methods for underwater vehicles are mostly based on dynamic modeling. Although there have been great advancements in algorithms for motion control, the consideration of fluid forces is not accurate enough. Turbulence effects such as wake vortex shedding, friction, viscous effects such as boundary layers, and flow separation effects are not well considered. Therefore, a more accurate flow field simulation method is needed to calculate fluid forces.

[0003] In recent years, the Computational Fluid Dynamics (CFD) method has been widely used in the design of underwater vehicles, and it can accurately simulate the process of fluid flow and its interaction with underwater vehicles. However, existing CFD-based research generally does not consider control and its effects. Even in a few studies where control is considered, it is open-loop control, which controls according to predetermined input forces and torques in advance, and this is very different from the actual situation. Summary of the Invention

[0004] Aiming at the deficiencies of the existing technology, the purpose of this application is to provide a closed-loop motion control simulation method and device for an underwater vehicle integrating CFD, aiming to solve the problems of low motion control accuracy of underwater vehicles and large differences from the actual situation in existing CFD-based research.

[0005] To achieve the above purpose, in the first aspect, this application provides a closed-loop motion control simulation method for an underwater vehicle integrating CFD, which is applied to simulation software and includes:

[0006] Obtain the required control force and control torque of the underwater vehicle at the current moment according to the deviation between the first pose of the underwater vehicle at the previous moment and the target pose.

[0007] Obtain the second pose of the underwater vehicle at the next moment according to the control force, control torque, flow field force and flow field torque received by the underwater vehicle at the current moment.

[0008] Update the first pose based on the second pose until the deviation between the updated first pose and the target pose is within a preset range.

[0009] Perform control simulation on the underwater vehicle based on the flow field force, flow field force, flow field torque, control force, control torque of the underwater vehicle at each moment and the multi-degree-of-freedom motion equation of the underwater vehicle.

[0010] In some embodiments, the flow field forces and flow field torques acting on the underwater vehicle at the current moment include:

[0011] Calculate the flow field forces and flow field torques based on the following formula;

[0012] f fluid = ∑ f p f a f - ∑ f τ f a f ;

[0013] n fluid = ∑ f [r f × (p f a f )] - ∑ f [r f × (τ f a f )];

[0014] In the formula, f fluid is the flow field force, f is the surface of the underwater vehicle, p f is the local pressure on the surface, a f is the normal vector of the surface, τ f is the shear stress on the surface, n fluid is the flow field torque, r f is the distance vector from the centroid of the underwater vehicle to the center of the surface.

[0015] In some embodiments, the method for obtaining the local pressure on the surface includes:

[0016] Calculate the local pressure based on the following formula;

[0017]

[0018] where df is the infinitesimal surface element on the surface, p is the sum of the static and dynamic pressures of the fluid, and is obtained based on the following formula;

[0019]

[0020]

[0021] In the formula, x, y, and z respectively represent the horizontal axis, vertical axis, and vertical axis of the Cartesian rectangular coordinate system, μ is the dynamic viscosity, ρ is the fluid density, u is the velocity vector field of the fluid, u x 、u y and u zrespectively represent the velocity components of the fluid in the horizontal axis direction, the vertical axis direction, and the vertical axis direction, X, Y, and Z are respectively the mass force components of the fluid in the horizontal axis direction, the vertical axis direction, and the vertical axis direction, and t is the previous moment.

[0022] In some embodiments, according to the deviation between the first pose of the underwater vehicle at the previous moment and the target pose, obtaining the required control force and control moment of the underwater vehicle at the current moment includes:

[0023] Obtaining the control force based on the following formula;

[0024]

[0025] In the formula, τ is the control force, e d (t) is the first deviation between the first position in the first pose at the previous moment t and the target position in the target pose, K p is the proportionality coefficient, T i is the integral time constant, T d is the differential time constant, and t + 1 is the current moment;

[0026] Obtaining the control moment based on the following formula;

[0027]

[0028] In the formula, τ θ is the control moment, e θ (t) is the second deviation between the first attitude in the first pose at the previous moment t and the target attitude in the target pose.

[0029] In some embodiments, according to the control force, the control moment, the flow field force and the flow field moment received by the underwater vehicle at the current moment, obtaining the second pose of the underwater vehicle at the next moment includes:

[0030] Based on the multi-degree-of-freedom motion equation of the underwater vehicle, obtaining the angular velocity and the velocity of the center of mass of the underwater vehicle;

[0031] Based on the angular velocity and the velocity of the center of mass, obtaining the second pose;

[0032] Among them, the multi-degree-of-freedom motion equation of the underwater vehicle is specifically:

[0033]

[0034] In the formula, m is the sum of the mass of the underwater vehicle and the added mass of the underwater vehicle, v is the velocity of the center of mass of the underwater vehicle, f fluid is the flow field force, f cThe external force generated by multi-body constraints or joints, τ is the control force, t + 1 is the current moment, M is the inertia moment tensor, ω is the angular velocity of the underwater vehicle, n fluid is the flow field moment, n c is the external torque generated by multi-body constraints or joints, τ θ is the control torque.

[0035] In some embodiments, based on the angular velocity and the velocity of the center of mass, obtaining the second pose includes:

[0036] Calculating the second pose based on the following formula;

[0037] Z d1 (t + 2) = Z d1 (t + 1) + v x Δt;

[0038] Z d2 (t + 2) = Z d2 (t + 1) + v y Δt;

[0039] Z d3 (t + 2) = Z d3 (t + 1) + v z Δt;

[0040] Z θ1 (t + 2) = Z θ1 (t + 1) + ω x Δt;

[0041] Z θ2 (t + 2) = Z θ2 (t + 1) + ω y Δt;

[0042] Z θ3 (t + 2) = Z θ3 (t + 1) + ω z Δt;

[0043] In the formula, Z d1 、Z d2 and Z d3 are the position components of the second position in the second pose in the horizontal axis direction, vertical axis direction and vertical axis direction respectively, t + 2 is the next moment, t + 1 is the current moment, v x 、v y and v z are the velocity components of the velocity of the center of mass in the horizontal axis direction, vertical axis direction and vertical axis direction respectively, Z θ1 、Z θ2 and Z θ3 are the rotation angle components of the second attitude in the second pose in the horizontal axis direction, vertical axis direction and vertical axis direction respectively, ωx , ω y and ω z are the angular velocity components of the underwater vehicle in the horizontal axis direction, vertical axis direction, and vertical axis direction respectively, and Δt is the interval between the next moment and the current moment.

[0044] In a second aspect, the present application provides a closed-loop motion control simulation device for an underwater vehicle integrating CFD, including:

[0045] A first acquisition module, configured to acquire the required control force and control moment of the underwater vehicle at the current moment according to the deviation between the first pose of the underwater vehicle at the previous moment and the target pose;

[0046] A second acquisition module, configured to acquire the second pose of the underwater vehicle at the next moment according to the control force, control moment, flow field force and flow field moment received by the underwater vehicle at the current moment;

[0047] An update module, configured to update the first pose based on the second pose until the deviation between the updated first pose and the target pose is within a preset range;

[0048] A control module, configured to perform control simulation on the underwater vehicle based on the flow field force, flow field force, flow field moment, control force, control moment of the underwater vehicle at each moment, and the multi-degree-of-freedom motion equation of the underwater vehicle.

[0049] In a third aspect, the present application provides an electronic device, including: at least one memory for storing a program; at least one processor for executing the program stored in the memory, and when the program stored in the memory is executed, the processor is configured to execute the method described in the first aspect or any of the embodiments of the first aspect.

[0050] In a fourth aspect, the present application provides a computer-readable storage medium storing a computer program, and when the computer program runs on a processor, it causes the processor to execute the method described in the first aspect or any of the embodiments of the first aspect.

[0051] In a fifth aspect, the present application provides a computer program product, and when the computer program product runs on a processor, it causes the processor to execute the method described in the first aspect or any of the embodiments of the first aspect.

[0052] Generally speaking, compared with the prior art, the above technical solutions conceived by the present application have the following beneficial effects:

[0053] The closed-loop motion control simulation method and device for an underwater vehicle integrating CFD provided by this application calculate the flow field forces and flow field torques applied to the underwater vehicle at the current moment based on the pose of the underwater vehicle at the previous moment; combine the control forces and control torques required at the current moment to perform control simulation on the underwater vehicle, so that the pose at the next moment changes. Update the pose at the previous moment based on the pose of the underwater vehicle at the next moment, and perform the solution of the next time step. Repeat this process until the deviation between the updated pose and the target pose is within the preset range, so as to achieve accurate simulation and real-time feedback of the navigation motion of the underwater vehicle, significantly improve the control accuracy, be closer to the actual operation process, and provide important support for the parameter adjustment and control method verification of the actual underwater vehicle. Description of the Drawings

[0054] Figure 1 is a schematic flow chart of the closed-loop motion control simulation method for an underwater vehicle integrating CFD provided by an embodiment of this application;

[0055] Figure 2 is a schematic flow chart of the PID control directly embedded with CFD provided by an embodiment of this application;

[0056] Figure 3 is a schematic diagram of the comparison of the heaving responses of an underwater vehicle at different diving depths under a sea state of level 5 under PID control provided by an embodiment of this application;

[0057] Figure 4 is a schematic diagram of the comparison of the heaving responses of an underwater vehicle at different diving depths under a sea state of level 6 under PID control provided by an embodiment of this application;

[0058] Figure 5 is a schematic diagram of the comparison of the pitching responses of an underwater vehicle at different diving depths under a sea state of level 5 under PID control provided by an embodiment of this application;

[0059] Figure 6 is a schematic diagram of the comparison of the pitching responses of an underwater vehicle at different diving depths under a sea state of level 6 under PID control provided by an embodiment of this application;

[0060] Figure 7 is a schematic structural diagram of the closed-loop motion control simulation device for an underwater vehicle integrating CFD provided by an embodiment of this application;

[0061] Figure 8 is a schematic structural diagram of the electronic device provided by an embodiment of this application. Detailed Embodiments

[0062] To make the objectives, technical solutions and advantages of this application more clear and understandable, the following further elaborates on this application in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not used to limit this application.

[0063] The term "and / or" in this document describes the association relationship of associated objects and indicates that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. The symbol " / " in this document indicates that the associated objects are in an "or" relationship. For example, A / B means A or B.

[0064] The terms "first", "second", etc. in the description and claims of this application are used to distinguish different objects, rather than to describe the specific order of the objects. For example, the first pose and the second pose are used to distinguish different poses, rather than to describe the specific order of the poses.

[0065] In the embodiments of this application, words such as "exemplary" or "for example" are used to give examples, illustrations or explanations. Any embodiment or design solution described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Rather, the use of words such as "exemplary" or "for example" is intended to present relevant concepts in a specific manner.

[0066] In the description of the embodiments of this application, unless otherwise specified, the meaning of "a plurality" refers to two or more.

[0067] This application first selects the geometric model of the underwater vehicle and its physical properties such as mass and centroid, and determines the target depth and direction of the underwater vehicle. In the simulation, information exchange occurs among the PID control force, the flow field force and the flow field moment, and the motion equation of the underwater vehicle at each time step. According to the position and attitude of the underwater vehicle model, the flow field is calculated through equations such as the Navier-Stokes equations (N-S equations) to obtain the flow field force and the flow field moment applied to the underwater vehicle; at the same moment, the control force and the control moment of the underwater vehicle are obtained through the PID control equation. After the flow field force and the flow field moment, and the control force and the control moment are transmitted to the six-degree-of-freedom motion equation of the underwater vehicle for calculation, the attitude and position of the underwater vehicle change. Subsequently, the new position and attitude of the underwater vehicle are transmitted to the flow field calculation equation and the PID control equation for the solution of the next time step, and this cycle continues.

[0068] The following describes the embodiments of this application in conjunction with the accompanying drawings in the embodiments of this application.

[0069] See Figure 1, the closed-loop motion control simulation method for an underwater vehicle integrating CFD provided by the embodiments of the present application is applied to simulation software and includes: step 110, step 120, step 130, and step 140.

[0070] In step 110, according to the deviation between the first pose of the underwater vehicle at the previous moment and the target pose, the required control force and control moment of the underwater vehicle at the current moment are obtained.

[0071] In step 120, according to the control force, control moment, flow field force and flow field moment received by the underwater vehicle at the current moment, the second pose of the underwater vehicle at the next moment is obtained.

[0072] In step 130, the first pose is updated based on the second pose until the deviation between the updated first pose and the target pose is within a preset range.

[0073] In step 140, control simulation of the underwater vehicle is performed based on the flow field force, flow field force, flow field moment, control force, control moment and multi-degree-of-freedom motion equation of the underwater vehicle at each moment.

[0074] In the embodiments of the present application, according to the pose of the underwater vehicle at the previous moment (i.e., the first pose, including the first attitude and the first position), the flow field force and flow field moment received by the underwater vehicle at the current moment can be calculated by the N-S equation.

[0075] According to the deviation between the first pose of the underwater vehicle at the previous moment and the target pose (including the target position and the target attitude), the required control force and control moment at the current moment can be calculated by the PID control equation. Among them, the deviation can specifically include the first deviation between the first position and the target position and the second deviation between the first attitude and the target attitude.

[0076] Using the multi-degree-of-freedom motion equation of the underwater vehicle, combined with the above-obtained flow field force, flow field moment, control force and control moment, the pose of the underwater vehicle at the next moment (i.e., the second pose, including the second attitude and the second position) is obtained to simulate the six-degree-of-freedom motion response of the underwater vehicle during navigation. Among them, the six-degree-of-freedom motion response includes heave, surge, sway, roll, pitch and yaw. Subsequently, the second position and the second attitude of the underwater vehicle are transmitted to the N-S equation and the PID control equation for the calculation of the next time step, and this cycle continues. Until the deviation between the updated first pose and the target pose is within a preset range. The preset range can be a reasonable range that enables the underwater vehicle to maintain stable navigation under different sea conditions and diving depths. The six-degree-of-freedom motion equation of the underwater vehicle is adopted in the embodiments of the present application.

[0077] During the control simulation process, according to the motion states of the underwater vehicle under different sea conditions and diving depths, by obtaining the flow field forces, flow field torques, control forces, and control torques applied to the underwater vehicle at each moment, and combining with the six-degree-of-freedom motion equation of the underwater vehicle, PID control is performed on the underwater vehicle to achieve stable navigation of the underwater vehicle.

[0078] The above motion control simulation method is directly embedded into a simulation software (such as CFD software) to form a closed-loop control method, so as to real-time feedback the control force and control torque, enabling the underwater vehicle to maintain stable navigation under different sea conditions and diving depths.

[0079] A closed-loop motion control simulation method for an underwater vehicle integrating CFD provided by an embodiment of the present application calculates the flow field forces and flow field torques applied to the underwater vehicle at the current moment according to the pose of the underwater vehicle at the previous moment; combines the control forces and control torques required at the current moment to perform control simulation on the underwater vehicle, so that the pose of the underwater vehicle at the next moment changes. The pose of the underwater vehicle at the previous moment is updated by the pose of the underwater vehicle at the next moment, and the solution of the next time step is carried out, and so on in a cycle until the deviation between the updated pose and the target pose is within a preset range, so as to achieve accurate simulation and real-time feedback of the navigation motion of the underwater vehicle, significantly improving the control accuracy, being closer to the actual operation process, and providing important support for the parameter adjustment and control method verification of the actual underwater vehicle.

[0080] Further, in some embodiments, in the above steps, the flow field forces and flow field torques received by the underwater vehicle at the current moment may include:

[0081] Calculate the flow field forces and flow field torques based on the following formula;

[0082] f fluid =∑ f p f a f -∑ f τ f a f ;

[0083] n fluid =∑ f [r f ×(p f a f )]-∑ f [r f ×(τ f a f )];

[0084] In the formula, f fluid is the flow field force, f is the surface of the underwater vehicle, p fis the local pressure on the surface, a f is the normal vector of the surface, τ f is the shear stress on the surface, n fluid is the moment of the flow field, r f is the distance vector from the centroid of the underwater vehicle to the center of the surface.

[0085] In the embodiment of the present application, by inputting the first pose and the flow field environment of the underwater vehicle at the previous moment into the N-S equation, the flow field force f fluid and the moment of the flow field n fluid can be obtained, specifically as follows:

[0086] f fluid = ∑ f p f a f - ∑ f τ f a f ;

[0087] n fluid = ∑ f [r f × (p f a f )] - ∑ f [r f × (τ f a f )];

[0088] In the formula, f is the surface of the underwater vehicle, p f is the local pressure on the surface, which can be obtained by integrating the sum of the static and dynamic pressures p of the fluid on the surface of the underwater vehicle, a f is the normal vector of the surface of the underwater vehicle, τ f is the shear stress on the surface of the underwater vehicle, r f is the distance vector from the centroid of the underwater vehicle to the center of the surface, μ is the dynamic viscosity, u is the velocity vector field of the fluid, and y is the longitudinal axis of the Cartesian rectangular coordinate system.

[0089] Furthermore, in some embodiments, in the above steps, the method for obtaining the local pressure on the surface may include:

[0090] Calculating the local pressure based on the following formula;

[0091]

[0092] where df is the infinitesimal surface element on the surface, and p is the sum of the static and dynamic pressures of the fluid, which is obtained based on the following formula;

[0093]

[0094] Wherein, x, y, and z respectively represent the horizontal axis, vertical axis, and vertical axis of the Cartesian rectangular coordinate system, μ is the dynamic viscosity, ρ is the fluid density, u is the velocity vector field of the fluid, u x , u y and u z respectively represent the velocity components of the fluid in the horizontal axis direction, vertical axis direction, and vertical axis direction, X, Y, and Z are respectively the mass force components of the fluid in the horizontal axis direction, vertical axis direction, and vertical axis direction, and t is the previous moment.

[0095] In the embodiment of the present application, the local pressure p on the surface of the underwater vehicle in the above steps f can be calculated by the following formula:

[0096]

[0097] wherein, df is the infinitesimal surface element on the surface, p is the sum of the static and dynamic pressures of the fluid, which can be calculated by the mass conservation equation and the N - S equation:

[0098]

[0099] Wherein, x, y, and z respectively represent the horizontal axis, vertical axis, and vertical axis of the Cartesian rectangular coordinate system, μ is the dynamic viscosity, ρ is the fluid density, u x , u y and u z respectively represent the velocity components of the fluid in the horizontal axis direction, vertical axis direction, and vertical axis direction, X, Y, and Z are respectively the mass force components of the fluid in the horizontal axis direction, vertical axis direction, and vertical axis direction, and t is the previous moment.

[0100] Furthermore, in some embodiments, in step 110, according to the deviation between the first pose of the underwater vehicle at the previous moment and the target pose, the required control force and control moment of the underwater vehicle at the current moment are obtained, including:

[0101] Based on the following formula, the control force is obtained;

[0102]

[0103] Wherein, τ is the control force, e d (t) is the first deviation between the first position in the first pose at the previous moment t and the target position in the target pose, K p is the proportionality coefficient, T i is the integral time constant, T d is the differential time constant, and t + 1 is the current moment;

[0104] Based on the following formula, the control moment is obtained;

[0105]

[0106] Where τ θ is the control torque, and e θ (t) is the second deviation between the first attitude in the first pose at the previous moment t and the target attitude in the target pose.

[0107] In the embodiments of the present application, by calculating the control force and control torque required by the underwater vehicle at the current moment based on the PID control equation, and by adjusting the parameters of the PID control equation in real time, the amplitude of the motion response of the underwater vehicle under different sea conditions and diving depths is kept within an acceptable range to achieve the smooth navigation of the underwater vehicle. Specifically as follows:

[0108] Based on the following formula, calculate the control force τ(t + 1) of the underwater vehicle at the current moment t + 1;

[0109]

[0110] Where e d (t) is the displacement deviation, i.e., the first deviation, between the first position in the first pose at the previous moment t and the target position in the target pose, K p is the proportionality coefficient, T i is the integral time constant, often expressed in the form of an integral coefficient, T is the differential time constant, often expressed in the form of a differential coefficient K d =K d T p T d Both the above-mentioned first position and the target position Z d can be composed of the position components of the underwater vehicle in the horizontal axis direction, the vertical axis direction, and the vertical axis direction.

[0111] Based on the following formula, obtain the control torque;

[0112]

[0113] Where τ θ is the control torque, and e θ (t) is the control deviation, i.e., the second deviation, between the first attitude in the first pose at the previous moment t and the target attitude in the target pose. Wherein, both the above-mentioned first attitude and the target attitude Z θ can be composed of the rotation angle components of the underwater vehicle in the horizontal axis direction, the vertical axis direction, and the vertical axis direction, and this rotation angle is the actual angle θ in the rotation direction.

[0114] Further, in some embodiments, in step 120, obtaining the second pose of the underwater vehicle at the next moment according to the control force, the control moment, the flow field force and the flow field moment received by the underwater vehicle at the current moment may include:

[0115] Based on the multi-degree-of-freedom motion equation of the underwater vehicle, obtain the angular velocity of the underwater vehicle and the velocity of the center of mass;

[0116] Based on the angular velocity and the velocity of the center of mass, obtain the second pose;

[0117] Among them, the multi-degree-of-freedom motion equation of the underwater vehicle is specifically:

[0118]

[0119] In the formula, m is the sum of the mass of the underwater vehicle and the added mass of the underwater vehicle, v is the velocity of the center of mass of the underwater vehicle, f fluid is the flow field force, f c is the external force generated by multi-body constraints or joints, τ is the control force, t + 1 is the current moment, M is the inertia moment tensor, ω is the angular velocity of the underwater vehicle, n fluid is the flow field moment, n c is the external moment generated by multi-body constraints or joints, τ θ is the control moment.

[0120] In the embodiments of the present application, the six-degree-of-freedom motion equation of the underwater vehicle is selected to calculate the angular velocity and the velocity of the center of mass of the underwater vehicle, specifically as follows:

[0121] The specific expression form of the six-degree-of-freedom motion equation of the underwater vehicle is:

[0122]

[0123] In the formula, m is the sum of the mass of the underwater vehicle and the added mass of the underwater vehicle, v is the velocity of the center of mass of the underwater vehicle, f c is the external force generated by multi-body constraints or joints, τ is the control force of the underwater vehicle at the current moment, which may include its control force components τ x 、τ y and τ z in the transverse axis direction, the longitudinal axis direction and the vertical axis direction, t + 1 is the current moment, M is the inertia moment tensor, ω is the angular velocity of the underwater vehicle, which may include its angular velocity components ω x 、ω y and ω z in the transverse axis direction, the longitudinal axis direction and the vertical axis direction, n c is the external moment generated by multi-body constraints or joints, τ θis the control moment of the underwater vehicle at the current moment, which may include its control moment components τ in the transverse axis direction, longitudinal axis direction, and vertical axis direction θx , τ θy and τ θz .

[0124] Calculate the angular velocity of the underwater vehicle and the velocity of the center of mass according to the six-degree-of-freedom motion equation of the underwater vehicle, and calculate the second position and second attitude in the second pose according to the angular velocity and the velocity of the center of mass.

[0125] The closed-loop motion control simulation method of the underwater vehicle integrating computational fluid dynamics provided by the embodiments of the present application calculates the flow field force and flow field moment applied to the underwater vehicle at the current moment according to the pose of the underwater vehicle at the previous moment by using hydrodynamic theories such as the Navier-Stokes equation; combines the closed-loop control algorithm to calculate the required control force and control moment at the current moment according to the pose deviation, and uses them as inputs to the six-degree-of-freedom motion equation of the underwater vehicle to perform motion control simulation, so that its pose changes at the next moment. The change of the vehicle pose will cause changes in the flow field, fluid force, and pose deviation. Therefore, it is necessary to update the pose of the underwater vehicle at the next moment, and calculate the flow field force and flow field moment, control force and control moment at the next time step according to the above process, and cycle in this way to continuously calculate and update the pose until the deviation between the updated pose and the target pose is within the preset range, so as to achieve accurate simulation and real-time feedback of the navigation motion of the underwater vehicle, significantly improve the control accuracy, be closer to the actual operation process, and provide important support for the parameter adjustment and control method verification of the actual underwater vehicle.

[0126] Further, in some embodiments, in the above steps, obtaining the second pose based on the angular velocity and the velocity of the center of mass may include:

[0127] Calculate the second pose based on the following formula;

[0128] Z d1 (t + 2)=Z d1 (t + 1)+v x Δt;

[0129] Z d2 (t + 2)=Z d2 (t + 1)+v y Δt;

[0130] Z d3 (t + 2)=Z d3 (t + 1)+v z Δt;

[0131] Z θ1 (t + 2)=Z θ1(t + 1)+ω x Δt;

[0132] Z θ2 (t + 2)=Z θ2 (t + 1)+ω y Δt;

[0133] Z θ3 (t + 2)=Z θ3 (t + 1)+ω z Δt;

[0134] Wherein, Z d1 , Z d2 and Z d3 are the position components of the second position in the second pose in the horizontal axis direction, vertical axis direction, and vertical axis direction respectively, t + 2 is the next moment, t + 1 is the current moment, v x , v y and v z are the velocity components of the center of mass in the horizontal axis direction, vertical axis direction, and vertical axis direction respectively, Z θ1 , Z θ2 and Z θ3 are the rotation angle components of the second attitude in the second pose in the horizontal axis direction, vertical axis direction, and vertical axis direction respectively, ω x , ω y and ω z are the angular velocity components of the underwater vehicle in the horizontal axis direction, vertical axis direction, and vertical axis direction respectively, and Δt is the interval between the next moment and the current moment.

[0135] In the embodiments of the present application, the second pose of the underwater vehicle at the next moment can be calculated based on the following formula, which can specifically include the second position and the second attitude;

[0136] Z d1 (t + 2)=Z d1 (t + 1)+v x Δt;

[0137] Z d2 (t + 2)=Z d2 (t + 1)+v y Δt;

[0138] Z d3 (t + 2)=Z d3 (t + 1)+v z Δt;

[0139] Z θ1 (t + 2)=Z θ1 (t + 1)+ω x Δt;

[0140] Z θ2 (t + 2)= Z θ2 (t + 1)+ ω y Δt;

[0141] Z θ3 (t + 2)= Z θ3 (t + 1)+ ω z Δt;

[0142] Wherein, Z d1 、Z d2 and Z d3 are the position components of the second position in the horizontal axis direction, vertical axis direction and vertical axis direction respectively, t + 2 is the next moment, v x 、v y and v z are the velocity components of the centroid velocity in the horizontal axis direction, vertical axis direction and vertical axis direction respectively, Z θ1 、Z θ2 and Z θ3 are the rotation angle components of the second attitude in the horizontal axis direction, vertical axis direction and vertical axis direction respectively, ω x 、ω y and ω z are the angular velocity components of the underwater vehicle's angular velocity in the horizontal axis direction, vertical axis direction and vertical axis direction respectively, and Δt is the interval between the next moment and the current moment.

[0143] Exemplarily, the DARPA underwater vehicle model SUBOFF is selected as the research object, and this model is a standard model for verifying the CFD calculation accuracy.

[0144] 1 Establish a numerical model of the flow field. Using the N - S equation, etc., establish the flow field environment under the target working conditions, including the full - appendage geometric model of the underwater vehicle, the flow field calculation domain and boundary condition setting, etc.

[0145] 2 Define the target pose, and clarify the control objectives when the underwater vehicle is navigating near the water surface, such as maintaining a specific depth and stable attitude.

[0146] 3 Design a PID controller. According to the motion response characteristics of the underwater vehicle, design a PID controller, including determining the controller parameters (proportional, integral, differential coefficients) and control strategies.

[0147] 4 Construct the six - degree - of - freedom motion equation of the underwater vehicle. Using the six - degree - of - freedom motion equation of the underwater vehicle, the flow field forces, flow field torques calculated by the N - S equation, and the control forces and control torques calculated by the PID control equation as inputs, calculate the six - degree - of - freedom motion responses such as heave and pitch of the underwater vehicle under different sea conditions (such as different wave heights, periods) and diving depths as outputs.

[0148] 5 Update the position and attitude of the underwater vehicle according to the calculation results of the previous step, and transfer them as inputs to the flow field calculation model established in step 1 and the PID control model established in step 4 to calculate the flow field forces, flow field moments, control forces, and control moments acting on the underwater vehicle at the next moment.

[0149] 6 Implement closed-loop control: Embed the PID control algorithm into the CFD simulation, and adjust the control forces and control moments in real time to make the underwater vehicle reach a stable state. Through repeated iterations, optimize the controller parameters until the underwater vehicle can maintain stable navigation under different working conditions.

[0150] 7 Result verification and analysis: Compare the control effects under different sea conditions and diving depths to verify the feasibility and effectiveness of the closed-loop control method. At the same time, analyze the motion response characteristics and control force requirements of the underwater vehicle under different working conditions to provide guidance for actual operation.

[0151] Among them, the full-appendage model of the SUBOFF underwater vehicle used in this application embodiment includes a rotating bare hull, a conning tower, and four stern rudder wings. The actual total length of the underwater vehicle is 104.5 meters, and a 24:1 scaled-down model is adopted. The specific dimensions are shown in Table 1.

[0152] Table 1

[0153]

[0154]

[0155] According to Froude similarity, set the speed of the underwater vehicle to 4 knots (take 0.42 m / s). The waves are generated in the form of regular waves, and the wave heights are taken as 4 meters, 5 meters, and 6 meters respectively (corresponding to sea states 4, 5, and 6. The actual wave height takes 1 / 24 of the actual sea state value), and the wave period is set according to the actual sea conditions. The diving depths are taken as 20 meters, 30 meters, and 50 meters respectively, and are also scaled down according to the scale.

[0156] The total length of the computational domain is 36 meters, the width is 20 meters, and the height is 27 meters, of which the underwater part is 18.5 meters. The underwater vehicle is located at the center of the computational domain. A hexahedral cut-cell grid is used to refine the grid on the surface of the underwater vehicle, near the wave surface, and in the key flow regions. The thickness of the first layer of the grid is 0.005 meters, and the total number of grids is approximately 4.03 million.

[0157] For the numerical simulation setup of CFD, the compressibility of seawater and the influence of water temperature are ignored. The Reynolds-averaged Navier-Stokes method (RANS) and the VOF (Volume of Fluid) wave model are adopted. The control equations include the mass conservation equation and the N-S equation. The SST k-ω model is selected for the turbulence model to accurately predict the fluid motion states in the near-wall region and the far field.

[0158] Please further refer to Figure 2 to establish the PID control equation, and calculate the required control force and control moment of the underwater vehicle in real time through the PID control equation.

[0159] Establish the six-degree-of-freedom motion equation of the underwater vehicle, and embed the PID control output term and the flow field calculation output term into it.

[0160] During the simulation process, PID closed-loop control is realized. According to the first position and the first attitude of the underwater vehicle at the previous moment, calculate the flow field force, flow field moment, control force and control moment of the underwater vehicle at the current moment through the N-S equation and the PID control equation respectively. Transfer the flow field force, flow field moment, control force and control moment to the six-degree-of-freedom motion equation of the underwater vehicle to simulate the motion response of the underwater vehicle in 6 degrees of freedom during navigation. The motion responses in 6 degrees of freedom include heave, surge, sway, roll, pitch and yaw. Subsequently, transfer the new position and attitude of the underwater vehicle to the N-S equation and the PID control equation for calculation in the next time step, and cycle in this way.

[0161] By comparing the motion responses of the underwater vehicle under no control and PID control, analyze the heave and pitch motion responses of the underwater vehicle under different sea conditions and diving depths, specifically as Figures 3 to 6 shown.

[0162] Please continue to refer to Figures 3 to 6 The simulation results show that PID control significantly reduces the heave and pitch amplitudes of the underwater vehicle when navigating near the water surface, especially more significantly under high sea conditions, as shown in Table 2 specifically.

[0163] Table 2

[0164]

[0165] Through detailed data analysis and simulation results, this application reveals the magnitude of the control force required for the underwater vehicle to maintain stable navigation under different sea conditions and diving depths, providing strong support for the actual operation and performance optimization of the underwater vehicle.

[0166] The closed-loop motion control simulation method for underwater vehicles integrating CFD provided in the embodiments of this application is more accurate than traditional dynamic modeling methods, and can better consider viscous effects such as fluid acting forces, wake vortex shedding, friction, boundary layers and flow separation. Through high-precision mesh generation and numerical simulation verification, the accuracy and stability of the underwater vehicle motion control are improved, providing important support for the PID parameter tuning and control method verification of actual submarines.

[0167] The following describes the underwater vehicle closed-loop motion control simulation device integrating CFD provided by the present application. The underwater vehicle closed-loop motion control simulation device integrating CFD described below can be correspondingly referred to the underwater vehicle closed-loop motion control simulation method integrating CFD described above.

[0168] See Figure 7 , the underwater vehicle closed-loop motion control simulation device integrating CFD provided by the embodiments of the present application may include: a first acquisition module 710, a second acquisition module 720, an update module 730, and a control module 740.

[0169] The first acquisition module 710 is configured to obtain the required control force and control torque of the underwater vehicle at the current moment according to the deviation between the first pose of the underwater vehicle at the previous moment and the target pose.

[0170] The second acquisition module 720 is configured to obtain the second pose of the underwater vehicle at the next moment according to the control force, the control torque, the flow field force and the flow field torque received by the underwater vehicle at the current moment.

[0171] The update module 730 is configured to update the first pose based on the second pose until the deviation between the updated first pose and the target pose is within a preset range.

[0172] The control module 740 is configured to perform control simulation on the underwater vehicle based on the flow field force, the flow field force, the flow field torque, the control force, the control torque of the underwater vehicle at each moment, and the multi-degree-of-freedom motion equation of the underwater vehicle.

[0173] The underwater vehicle closed-loop motion control simulation device integrating CFD provided by the embodiments of the present application calculates the flow field force and the flow field torque applied to the underwater vehicle at the current moment according to the pose of the underwater vehicle at the previous moment; combines the control force and the control torque required at the current moment to perform control simulation on the underwater vehicle, so that the pose of the underwater vehicle at the next moment changes. The pose of the underwater vehicle at the previous moment is updated through the pose of the underwater vehicle at the next moment, and the solution of the next time step is performed, and so on, until the deviation between the updated pose and the target pose is within a preset range, so as to realize the accurate simulation and real-time feedback of the navigation motion of the underwater vehicle, significantly improve the control accuracy, be closer to the actual operation process, and provide important support for the parameter adjustment and control method verification of the actual underwater vehicle.

[0174] It can be understood that the detailed function implementation of the above-mentioned each unit / module can be referred to the introduction in the foregoing method embodiments, and will not be elaborated herein.

[0175] It should be understood that the above device is used to execute the method in the above embodiment. For the corresponding program modules in the device, their implementation principles and technical effects are similar to those described in the above method. The working process of this device can refer to the corresponding process in the above method, and will not be elaborated here.

[0176] Based on the method in the above embodiment, an embodiment of the present application provides an electronic device. Refer to Figure 8 , this electronic device may include: a processor (Processor) 810, a communication interface (Communications Interface) 820, a memory (Memory) 830, and a communication bus 840. Among them, the processor 810, the communication interface 820, and the memory 830 complete mutual communication through the communication bus 840. The processor 810 can call the logical instructions in the memory 830 to execute the method in the above embodiment.

[0177] In addition, when the logical instructions in the above-mentioned memory 830 are implemented in the form of a software functional unit and sold or used as an independent product, they can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, or a part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to enable a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application.

[0178] Based on the method in the above embodiment, an embodiment of the present application provides a computer-readable storage medium. The computer-readable storage medium stores a computer program. When the computer program runs on a processor, it enables the processor to execute the method in the above embodiment.

[0179] Based on the method in the above embodiment, an embodiment of the present application provides a computer program product. When the computer program product runs on a processor, it enables the processor to execute the method in the above embodiment.

[0180] It can be understood that the processor in the embodiments of the present application may be a central processing unit (CPU), or may also be other general-purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. The general-purpose processor may be a microprocessor or any conventional processor.

[0181] The method steps in the embodiments of the present application may be implemented in a hardware manner or by a processor executing software instructions. The software instructions may be composed of corresponding software modules, and the software modules may be stored in a random access memory (RAM), flash memory, read-only memory (ROM), programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), registers, hard disks, removable hard disks, CD-ROMs, or any other form of storage medium well known in the art. An exemplary storage medium is coupled to the processor so that the processor can read information from the storage medium and write information to the storage medium. Of course, the storage medium may also be a component of the processor. The processor and the storage medium may be located in an ASIC.

[0182] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the processes or functions described in the embodiments of the present application are generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium or transmitted through the computer-readable storage medium. The computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center in a wired manner (such as coaxial cable, optical fiber, digital subscriber line (DSL)) or wirelessly (such as infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more integrated available media. The available medium can be a magnetic medium (such as a floppy disk, hard disk, magnetic tape), an optical medium (such as a DVD), or a semiconductor medium (such as a solid state disk (SSD)), etc.

[0183] It can be understood that the various numerical numbers involved in the embodiments of the present application are only for the convenience of description and are not used to limit the scope of the embodiments of the present application.

[0184] Those skilled in the art can easily understand that the above is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A closed-loop motion control simulation method for an underwater vehicle integrating CFD, characterized in that, Applied to simulation software, including: Obtain the required control force and control moment of the underwater vehicle at the current moment according to the deviation between the first pose of the underwater vehicle at the previous moment and the target pose; Obtain the second pose of the underwater vehicle at the next moment according to the control force, the control moment, the flow field force and the flow field moment that the underwater vehicle receives at the current moment; Update the first pose based on the second pose until the deviation between the updated first pose and the target pose is within a preset range; Perform control simulation on the underwater vehicle based on the flow field force, the flow field force, the flow field moment, the control force, the control moment and the multi-degree-of-freedom motion equation of the underwater vehicle at each moment; The obtaining of the second pose of the underwater vehicle at the next moment according to the control force, the control moment, the flow field force and the flow field moment that the underwater vehicle receives at the current moment includes: Obtain the angular velocity of the underwater vehicle and the velocity of the center of mass based on the multi-degree-of-freedom motion equation of the underwater vehicle; Obtain the second pose based on the angular velocity and the velocity of the center of mass; Wherein, the multi-degree-of-freedom motion equation of the underwater vehicle is specifically: ； ； In the formula, is the sum of the mass of the underwater vehicle and the added mass of the underwater vehicle, is the velocity of the center of mass of the underwater vehicle, is the flow field force, is the external force generated by multi-body constraints or joints, is the control force, is the current moment, is the inertia moment tensor, is the angular velocity of the underwater vehicle, is the flow field torque, is the external torque generated by multi-body constraints or joints, is the control torque; The obtaining of the second pose based on the angular velocity and the velocity of the center of mass includes: Calculate the second pose based on the following formula; ； ； ； ； ； ； Wherein, , and are the position components of the second position in the second pose in the horizontal axis direction, vertical axis direction, and vertical axis direction respectively, is the next moment, is the current moment, , and are the velocity components of the centroid velocity in the horizontal axis direction, vertical axis direction, and vertical axis direction respectively, , and are the rotation angle components of the second attitude in the second pose in the horizontal axis direction, vertical axis direction, and vertical axis direction respectively, , and are the angular velocity components of the underwater vehicle's angular velocity in the horizontal axis direction, vertical axis direction, and vertical axis direction respectively, is the interval between the next moment and the current moment.

2. The closed-loop motion control simulation method for an underwater vehicle integrating CFD according to claim 1, wherein, Applied to simulation software, the flow field force and the flow field moment that the underwater vehicle receives at the current moment include: Calculate the flow field force and the flow field moment based on the following formula; ； ； In the formula, is the flow field force, is the surface of the underwater vehicle, is the local pressure on the surface, is the normal vector of the surface, is the shear stress on the surface, is the flow field moment, is the distance vector from the centroid of the underwater vehicle to the center of the surface.

3. The closed-loop motion control simulation method for an underwater vehicle integrating CFD according to claim 2, characterized in that Applied to simulation software, the obtaining method of the local pressure on the surface includes: Calculate the local pressure based on the following formula; ； wherein, is a small surface element on the said surface, is the sum of the static and dynamic pressures of the fluid, and is obtained based on the following formula; ； ； ； ； In the formula, , and respectively represent the horizontal axis, vertical axis and vertical axis of the Cartesian rectangular coordinate system. is the dynamic viscosity. is the fluid density. is the velocity vector field of the fluid. , and respectively represent the velocity components of the fluid in the horizontal axis direction, vertical axis direction and vertical axis direction. , and are respectively the mass force components of the fluid in the horizontal axis direction, vertical axis direction and vertical axis direction. is the previous moment.

4. The closed-loop motion control simulation method for an underwater vehicle integrating CFD according to claim 1, characterized in that Applied to simulation software, the obtaining of the required control force and control moment of the underwater vehicle at the current moment according to the deviation between the first pose of the underwater vehicle at the previous moment and the target pose includes: Obtain the control force based on the following formula; ； Wherein, is the control force, is the first deviation between the first position in the first pose at the previous moment and the target position in the target pose, is the proportionality coefficient, is the integral time constant, is the differential time constant, is the current moment; Obtain the control moment based on the following formula; ； wherein, is the control torque, is the second deviation between the first attitude in the first pose at the previous moment and the target attitude in the target pose.

5. A closed-loop motion control simulation device for an underwater vehicle integrating CFD, characterized in that, Including: A first obtaining module, configured to obtain the required control force and control moment of the underwater vehicle at the current moment according to the deviation between the first pose of the underwater vehicle at the previous moment and the target pose; A second obtaining module, configured to obtain the second pose of the underwater vehicle at the next moment according to the control force, the control moment, the flow field force and the flow field moment that the underwater vehicle receives at the current moment; An updating module, configured to update the first pose based on the second pose until the deviation between the updated first pose and the target pose is within a preset range; A control module, configured to perform control simulation on the underwater vehicle based on the flow field force, the flow field force, the flow field moment, the control force, the control moment and the multi-degree-of-freedom motion equation of the underwater vehicle at each moment; The obtaining of the second pose of the underwater vehicle at the next moment according to the control force, the control moment, the flow field force and the flow field moment that the underwater vehicle receives at the current moment includes: Based on the multi-degree-of-freedom motion equation of the underwater vehicle, obtain the angular velocity of the underwater vehicle and the velocity of the center of mass; Based on the angular velocity and the velocity of the center of mass, obtain the second pose; wherein, the multi-degree-of-freedom motion equation of the underwater vehicle is specifically: ； ； In the formula, is the sum of the mass of the underwater vehicle and the added mass of the underwater vehicle, is the velocity of the center of mass of the underwater vehicle, is the flow field force, is the external force generated by multi-body constraints or joints, is the control force, is the current moment, is the inertia moment tensor, is the angular velocity of the underwater vehicle, is the flow field torque, is the external torque generated by multi-body constraints or joints, is the control torque; The obtaining of the second pose based on the angular velocity and the velocity of the center of mass includes: Calculate the second pose based on the following formula; ； ； ； ； ； ； Wherein, , and are the position components of the second position in the second pose in the horizontal axis direction, vertical axis direction, and vertical axis direction respectively, is the next moment, is the current moment, , and are the velocity components of the centroid velocity in the horizontal axis direction, vertical axis direction, and vertical axis direction respectively, , and are the rotation angle components of the second attitude in the second pose in the horizontal axis direction, vertical axis direction, and vertical axis direction respectively, , and are the angular velocity components of the underwater vehicle's angular velocity in the horizontal axis direction, vertical axis direction, and vertical axis direction respectively, is the interval between the next moment and the current moment.

6. An electronic device, characterized in that, including: At least one memory for storing a computer program; At least one processor for executing the program stored in the memory. When the program stored in the memory is executed, the processor is used to execute the closed-loop motion control simulation method of the underwater vehicle integrating CFD as described in any one of claims 1-4.

7. A computer-readable storage medium storing a computer program, characterized in that, When the computer program runs on the processor, the processor is caused to execute the closed-loop motion control simulation method of the underwater vehicle integrating CFD as described in any one of claims 1-4.

8. A computer program product, characterized in that, When the computer program product runs on the processor, the processor is caused to execute the closed-loop motion control simulation method of the underwater vehicle integrating CFD as described in any one of claims 1-4.

Images