CFD-fused underwater vehicle closed-loop motion control simulation method and device

Abstract

The invention belongs to the technical field of motion control, and particularly discloses a CFD-fused underwater vehicle closed-loop motion control simulation method and device. The method comprises the following steps: calculating a flow field force and a flow field moment applied to the underwater vehicle at the current moment by adopting fluid dynamic theories such as an N-S equation according to the pose of the underwater vehicle at the previous moment; and a control force and a control moment required at the current moment are calculated by combining a closed-loop control algorithm according to the pose deviation and are input to a six-degree-of-freedom motion equation of the aircraft, and motion control simulation is carried out. Therefore, the pose of the aircraft at the next moment changes, and changes of a flow field, fluid acting force and pose deviation can be caused, so that the pose needs to be updated and circularly calculated until the pose deviation is within a preset range. According to the method, accurate simulation and real-time feedback of the navigation motion of the underwater vehicle are realized, the control precision is remarkably improved, the method is closer to an actual control process, and important support is provided for actual parameter adjustment, control method verification and the like.

Description

Technical Field

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

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

[0003] In recent years, computational fluid dynamics (CFD) methods have been widely used in underwater vehicle design, which can accurately simulate the flow of fluid and its interaction with underwater vehicles. However, existing CFD-based research generally does not consider control and its effects. Even if a small number of studies have done control, they are open-loop control, which is controlled according to the predetermined input force and torque in advance, which is very different from the actual situation. Summary of the invention

[0004] In view of the defects of the prior art, the purpose of the present application is to provide a closed-loop motion control simulation method and device for underwater vehicles integrating CFD, aiming to solve the problems existing in the prior art that the motion control accuracy of underwater vehicles based on CFD research is low and differs greatly from the actual situation.

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

[0006] According to the deviation between the first posture of the underwater vehicle at the previous moment and the target posture, the control force and control torque required by the underwater vehicle at the current moment are obtained;

[0007] Obtaining a second posture 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 to which the underwater vehicle is subjected at the current moment;

[0008] 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;

[0009] Based on the flow field force, flow field force, flow field moment, control force, control moment and multi-degree-of-freedom motion equations of the underwater vehicle at each moment, the control simulation of the underwater vehicle is carried out.

[0010] In some embodiments, the flow field force and flow field moment to which the underwater vehicle is subjected at the current moment include:

[0011] The flow field force and flow field moment are calculated based on the following formulas;

[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, and p f is the local pressure on the surface, a f is the surface normal vector, τ f is the shear stress on the surface, n fluid is the flow field torque, r f is the distance vector from the center of mass of the underwater vehicle to the center of the surface.

[0015] In some embodiments, the local pressure on the surface is obtained by:

[0016] The local pressure is calculated based on the following formula;

[0017]

[0018] Where df is a tiny 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:

[0019]

[0020]

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

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

[0023] Based on the following formula, the control force is obtained;

[0024]

[0025] Where 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 integration time constant, T d is the differential time constant, t+1 is the current moment;

[0026] Based on the following formula, the control torque is obtained;

[0027]

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

[0029] In some embodiments, obtaining a second posture 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 to which the underwater vehicle is subjected at the current moment includes:

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

[0031] Based on the angular velocity and the velocity of the center of mass, obtain the second posture;

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

[0033]

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

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

[0036] Based on the following formula, calculate the second pose;

[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 posture in the horizontal, longitudinal and vertical directions, 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, longitudinal and vertical directions, respectively, Z θ1 , Z θ2 and Z θ3 are the rotation angle components of the second posture in the second position in the horizontal, longitudinal and vertical directions, ωx ,ω y and ω z are the angular velocity components of the underwater vehicle in the horizontal, longitudinal and vertical directions 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, comprising:

[0045] A first acquisition module, used for acquiring the control force and control torque required by the underwater vehicle at the current moment according to the deviation between the first posture of the underwater vehicle at the previous moment and the target posture;

[0046] A second acquisition module, used for acquiring a second posture of the underwater vehicle at a next moment according to the control force, the control torque, the flow field force and the flow field torque to which the underwater vehicle is subjected at the current moment;

[0047] An updating module, used for updating 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] The control module is used to perform control simulation on the underwater vehicle based on the flow field force, flow field force, flow field moment, control force, control moment and multi-degree-of-freedom motion equations of the underwater vehicle at each moment.

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

[0050] In a fourth aspect, the present application provides a computer-readable storage medium, which stores a computer program. When the computer program runs on a processor, the processor executes the method described in the first aspect or any embodiments of the first aspect.

[0051] In a fifth aspect, the present application provides a computer program product. When the computer program product runs on a processor, the processor executes the method described in the first aspect or any embodiments of the first aspect.

[0052] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the prior art:

[0053] The closed-loop motion control simulation method and device for underwater vehicles integrated with CFD provided in the present application calculate the flow field force and flow field torque applied to the underwater vehicle at the current moment according to the position and posture of the underwater vehicle at the previous moment; and perform control simulation on the underwater vehicle in combination with the control force and control torque required at the current moment, so that its position and posture at the next moment change. The position and posture of the underwater vehicle at the previous moment are updated by the position and posture of the underwater vehicle at the next moment, and the next time step is solved, and this cycle is repeated until the deviation between the updated position and posture and the target position and posture is within a preset range, so as to realize accurate simulation and real-time feedback of the navigation motion of the underwater vehicle, significantly improve the control accuracy, and be closer to the actual operation process, providing important support for the parameter adjustment and control method verification of the actual underwater vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0055] Figure 2 It is a schematic diagram of the PID control flow directly embedded in CFD provided by an embodiment of the present application;

[0056] Figure 3 It is a schematic diagram comparing the heave responses of underwater vehicles at different diving depths under PID control in five sea conditions provided in an embodiment of the present application;

[0057] Figure 4 It is a schematic diagram comparing the heave responses of underwater vehicles at different diving depths under PID control in six sea conditions provided in an embodiment of the present application;

[0058] Figure 5 It is a schematic diagram comparing the pitch response of underwater vehicles at different diving depths under PID control in five sea conditions provided in an embodiment of the present application;

[0059] Figure 6 It is a schematic diagram comparing the pitch response of underwater vehicles at different diving depths under PID control in six sea conditions provided by an embodiment of the present application;

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

[0061] Figure 8 It is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0062] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0063] The term "and / or" in this article is a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. The symbol " / " in this article indicates that the associated objects are in an or relationship, for example, A / B means A or B.

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

[0065] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0066] In the description of the embodiments of the present application, unless otherwise specified, “plurality” means two or more than two.

[0067] The present application first selects the geometric model of the underwater vehicle and its physical properties such as mass and center of mass to determine the target depth and direction of the underwater vehicle. In the simulation, the PID control force, flow field force and flow field torque, and underwater vehicle motion equation exchange information at each time step. According to the position and attitude of the underwater vehicle model, the flow field is calculated by the Navier-Stokes equations (NS) and the like to obtain the flow field force and flow field torque applied to the underwater vehicle; at the same time, the PID control equation is used to obtain the control force and control torque of the underwater vehicle. After the flow field force and flow field torque, control force and control torque are passed to the six-degree-of-freedom motion equation of the underwater vehicle and settled, the attitude and position of the underwater vehicle change. Subsequently, the new position and attitude of the underwater vehicle are passed to the flow field calculation equation and the PID control equation to solve the next time step, and this cycle is repeated.

[0068] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

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

[0070] Step 110 obtains the control force and control torque required by the underwater vehicle at the current moment according to the deviation between the first posture of the underwater vehicle at the previous moment and the target posture;

[0071] Step 120: obtaining a second posture 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 to which the underwater vehicle is subjected at the current moment;

[0072] Step 130 updates 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;

[0073] Step 140 performs control simulation on the underwater vehicle based on the flow field force, flow field force, flow field moment, control force, control moment and multi-degree-of-freedom motion equations of the underwater vehicle at each moment.

[0074] In the embodiment of the present application, based on the posture of the underwater vehicle at the previous moment (i.e., the first posture, including the first attitude and the first position), the flow field force and flow field torque exerted on the underwater vehicle at the current moment can be calculated by the NS equation.

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

[0076] By using the multi-degree-of-freedom motion equation of the underwater vehicle, combined with the flow field force, flow field moment, control force and control moment obtained above, the position and posture of the underwater vehicle at the next moment (i.e., the second position and the second position) are obtained to simulate the 6-degree-of-freedom motion response of the underwater vehicle during navigation. Among them, the 6-degree-of-freedom motion response includes vertical swing, vertical swing, horizontal swing, pitch, roll and bow swing. Then, the second position and the second posture of the underwater vehicle are passed to the NS equation and the PID control equation, and the calculation of the next time step is performed, and this cycle is repeated. Until the deviation between the updated first posture and the target posture is within a preset range. The preset range can be a reasonable range that allows the underwater vehicle to maintain stable navigation under different sea conditions and diving depths. The embodiment of the present application adopts the six-degree-of-freedom motion equation of the underwater vehicle.

[0077] During the control simulation process, according to the motion state of the underwater vehicle under different sea conditions and diving depths, PID control is performed on the underwater vehicle based on the flow field force, flow field moment, control force, and control moment applied to the underwater vehicle at each moment, and combined with the six-degree-of-freedom motion equation of the underwater vehicle, so as to achieve stable navigation of the underwater vehicle.

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

[0079] The embodiment of the present application provides a closed-loop motion control simulation method for underwater vehicles that integrates CFD. According to the posture of the underwater vehicle at the previous moment, the flow field force and flow field torque applied to the underwater vehicle at the current moment are calculated; combined with the control force and control torque required at the current moment, the underwater vehicle is controlled and simulated so that its posture at the next moment changes. The posture of the underwater vehicle at the previous moment is updated by the posture of the underwater vehicle at the next moment, and the next time step is solved. This cycle is repeated until the deviation between the updated posture and the target posture is within a 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, and be closer to the actual operation process, providing important support for the parameter adjustment and control method verification of actual underwater vehicles.

[0080] Furthermore, in some embodiments, in the above steps, the flow field force and flow field moment to which the underwater vehicle is subjected at the current moment may include:

[0081] The flow field force and flow field moment are calculated based on the following formulas;

[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, and p fis the local pressure on the surface, a f is the surface normal vector, τ f is the shear stress on the surface, n fluid is the flow field torque, r f is the distance vector from the center of mass of the underwater vehicle to the center of the surface.

[0085] In the embodiment of the present application, by inputting the first position of the underwater vehicle at the last moment and the flow field environment into the NS equation, the flow field force f can be obtained. fluid and flow field moment n fluid , 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] Where 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 over 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 center of mass 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 vertical axis of the Cartesian rectangular coordinate system.

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

[0090] The local pressure is calculated based on the following formula;

[0091]

[0092] Where df is a tiny 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] Where x, y and z represent the horizontal, vertical and vertical axes of the Cartesian coordinate system, μ is the dynamic viscosity, ρ is the fluid density, u is the velocity vector field of the fluid, and u x 、u y and u z represent the velocity components of the fluid in the horizontal, vertical and vertical directions respectively, X, Y and Z are the mass force components of the fluid in the horizontal, vertical and vertical directions respectively, 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 is f It can be calculated by the following formula:

[0096]

[0097] Where df is a tiny element on the surface, and p is the sum of the static and dynamic pressures of the fluid, which can be calculated using the mass conservation equation and the NS equation:

[0098]

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

[0100] Further, in some embodiments, in step 110, according to the deviation between the first posture of the underwater vehicle at the previous moment and the target posture, obtaining the control force and control torque required by the underwater vehicle at the current moment includes:

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

[0102]

[0103] Where 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 integration time constant, T d is the differential time constant, t+1 is the current moment;

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

[0105]

[0106] In the formula, τ θ is the control torque, e θ (t) is the second deviation between the first posture in the first posture at the previous time t and the target posture in the target posture.

[0107] In the embodiment of the present application, the control force and control torque required by the underwater vehicle at the current moment are calculated based on the PID control equation, and the parameters of the PID control equation are adjusted in real time to keep the motion response amplitude of the underwater vehicle in different sea conditions and diving depths within an acceptable range, so as to achieve stable navigation of the underwater vehicle. The details are as follows:

[0108] The control force τ(t+1) of the underwater vehicle at the current time t+1 is calculated based on the following formula:

[0109]

[0110] In the formula, e d (t) is the displacement deviation between the first position in the first pose at the previous moment t and the target position in the target pose, that is, the first deviation, K p is the proportionality coefficient, T i is the integration time constant, often expressed as the integration coefficient In the form of T d is the differential time constant, often expressed as the differential coefficient K d =K p T d In the form of. Wherein, the first position and the target position Z d They can all be composed of the position components of the underwater vehicle in the horizontal axis direction, the longitudinal axis direction and the vertical axis direction.

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

[0112]

[0113] In the formula, τ θ is the control torque, e θ (t) is the control deviation between the first posture in the first posture at the previous moment t and the target posture in the target posture, that is, the second deviation. θ They can all be composed of the rotation angle components of the underwater vehicle in the horizontal axis direction, the longitudinal axis direction and the vertical axis direction, and the rotation angle is the actual angle θ of the rotation direction.

[0114] Further, in some embodiments, in step 120, obtaining a second posture 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 to which the underwater vehicle is subjected at the current moment may include:

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

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

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

[0118]

[0119] Where m is the sum of the mass of the underwater vehicle and the additional mass of the underwater vehicle, v is the velocity of the center of mass of the underwater vehicle, and f is 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 moment of inertia tensor, ω is the angular velocity of the underwater vehicle, and n fluid is the flow field torque, n c is the external torque generated by the multibody constraints or joints, τ θ To control the torque.

[0120] In the embodiment 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, as follows:

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

[0122]

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

[0124] The angular velocity and the velocity of the center of mass of the underwater vehicle are calculated according to the above-mentioned six-degree-of-freedom motion equation of the underwater vehicle, and the second position and the second posture in the second position are calculated according to the angular velocity and the velocity of the center of mass.

[0125] The closed-loop motion control simulation method of underwater vehicles integrated with computational fluid dynamics provided in the embodiment of the present application, according to the posture of the underwater vehicle at the previous moment, the fluid dynamics theory such as the Navier-Stokes equation is used to calculate the flow field force and flow field torque applied to the underwater vehicle at the current moment; the control force and control torque required at the current moment are calculated according to the posture deviation in combination with the closed-loop control algorithm, and are given as input to the six-degree-of-freedom motion equation of the underwater vehicle to perform motion control simulation, so that its posture at the next moment changes. The change of the vehicle's posture will cause the change of the flow field, fluid force and posture deviation, so it is necessary to update the posture of the underwater vehicle at the next moment, and solve the flow field force and flow field torque, control force and control torque at the next time step according to the above process, so as to cycle and continuously calculate and update the posture until the deviation between the updated posture and the target posture is within the 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, and 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] Furthermore, in some embodiments, in the above steps, obtaining the second posture based on the angular velocity and the velocity of the center of mass may include:

[0127] Based on the following formula, calculate the second pose;

[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] In the formula, Z d1 , Z d2 and Z d3 are the position components of the second position in the second posture in the horizontal, longitudinal and vertical directions, 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, longitudinal and vertical directions, respectively, Z θ1 , Z θ2 and Z θ3 are the rotation angle components of the second posture in the second position in the horizontal, longitudinal and vertical directions, ω x ,ω y and ω z are the angular velocity components of the underwater vehicle in the horizontal, longitudinal and vertical directions respectively, and Δt is the interval between the next moment and the current moment.

[0135] In the embodiment of the present application, the second posture of the underwater vehicle at the next moment may be calculated based on the following formula, which may specifically include the second position and the second posture;

[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] In the formula, Z d1 , Z d2 and Z d3 are the position components of the second position in the horizontal, vertical and vertical directions respectively, t+2 is the next moment, v x 、v y and v z are the velocity components of the center of mass in the horizontal, longitudinal and vertical directions, respectively, Z θ1 , Z θ2 and Z θ3 are the rotation angle components of the second posture in the horizontal, longitudinal and vertical directions, ω x ,ω y and ω z are the angular velocity components of the underwater vehicle in the horizontal, longitudinal and vertical directions 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, which is a standard model for verifying the accuracy of CFD calculations.

[0144] 1. Establish a numerical model of the flow field, and use the NS equations to establish the flow field environment under the target working conditions, including the full appendage geometry model of the underwater vehicle, the flow field calculation domain, and the boundary condition settings.

[0145] 2. Define the target posture and clarify the control objectives of the underwater vehicle when it is sailing near the water surface, such as maintaining a specific depth and maintaining a stable posture.

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

[0147] 4. Construct the six-degree-of-freedom motion equation of the underwater vehicle. Through the six-degree-of-freedom motion equation of the underwater vehicle, the flow field force and flow field torque calculated by the NS equation, and the control force and control torque calculated by the PID control equation are used as input, and the six-degree-of-freedom motion response of the underwater vehicle such as heave and pitch under different sea conditions (such as different wave heights and periods) and diving depths is calculated as output.

[0148] 5 According to the calculation results of the previous step, the position and attitude of the underwater vehicle are updated and transmitted as input to the flow field calculation model established in step 1 and the PID control model established in step 4 to calculate the flow field force, flow field moment, control force and control moment of 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 force and control torque 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 SUBOFF underwater vehicle full-body model used in the embodiment of the present application includes a rotating bare hull, a command platform and four tail rudder wings. The actual total length of the underwater vehicle is 104.5 meters. 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's method, the speed of the underwater vehicle is set to 4 knots (0.42m / s), the waves are generated in the form of regular waves, the wave heights are 4 meters, 5 meters and 6 meters (corresponding to the fourth, fifth and sixth level sea conditions, the actual wave height is 1 / 24 of the actual value of the sea condition), and the wave period is set according to the actual sea conditions. The diving depths are 20 meters, 30 meters and 50 meters, which are also reduced 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 in the center of the computational domain. The six-faceted cut volume grid is used to encrypt the grids on the surface of the underwater vehicle, near the wave surface, and in the key flow area. The first layer of grid thickness is 0.005 meters, and the total number of grids is about 4.03 million.

[0157] The CFD numerical simulation was built by ignoring the compressibility of seawater and the influence of water temperature, and using the Reynolds-averaged Navier-Stokes method (RANS) and VOF (Volume of Fluid) wave model. The control equations include the mass conservation equation and the NS equation, and the turbulence model uses the SST k-ω model to accurately predict the fluid motion state near the wall and in the far field.

[0158] Please see further Figure 2 , the PID control equation is constructed, and the control force and control torque required by the underwater vehicle are calculated in real time through the PID control equation.

[0159] The six-degree-of-freedom motion equation of the underwater vehicle is constructed, and the PID control output items and flow field calculation output items are embedded in it.

[0160] During the simulation, PID closed-loop control was realized. According to the first position and first attitude of the underwater vehicle at the previous moment, the flow field force, flow field moment, control force and control moment of the underwater vehicle at the current moment were calculated respectively by the NS equation and the PID control equation. The flow field force, flow field moment, control force and control moment were transferred to the six-degree-of-freedom motion equation of the underwater vehicle, and the six-degree-of-freedom motion response of the underwater vehicle during navigation was simulated. The six-degree-of-freedom motion response includes heave, longitudinal sway, lateral sway, pitch, roll and bow sway. Then the new position and attitude of the underwater vehicle were transferred to the NS equation and the PID control equation, and the calculation of the next time step was carried out, and this cycle was repeated.

[0161] By comparing the motion responses of underwater vehicles without control and under PID control, the heave and pitch motion responses of underwater vehicles under different sea conditions and diving depths are analyzed. Figure 3 to Figure 6 shown.

[0162] Please continue to see Figure 3 to Figure 6 The simulation results show that PID control significantly reduces the heave and pitch amplitudes of the underwater vehicle when it is sailing near the water surface, especially in high sea conditions, as shown in Table 2.

[0163] Table 2

[0164]

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

[0166] The underwater vehicle closed-loop motion control simulation method integrated with CFD provided in the embodiment of the present application is more accurate than the traditional dynamic modeling method, and can better consider the viscosity effects such as fluid force, wake vortex shedding, friction, boundary layer and flow separation. Through high-precision meshing and numerical simulation verification, the accuracy and stability of underwater vehicle motion control are improved, providing important support for the PID parameter adjustment and control method verification of actual submersibles.

[0167] The underwater vehicle closed-loop motion control simulation device integrated with CFD provided in the present application is described below. The underwater vehicle closed-loop motion control simulation device integrated with CFD described below and the underwater vehicle closed-loop motion control simulation method integrated with CFD described above can be referenced to each other.

[0168] See also Figure 7 The underwater vehicle closed-loop motion control simulation device integrating CFD provided in an embodiment 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] A first acquisition module 710, for acquiring the control force and control torque required by the underwater vehicle at the current moment according to the deviation between the first posture of the underwater vehicle at the previous moment and the target posture;

[0170] A second acquisition module 720, configured to acquire a second posture of the underwater vehicle at a next moment according to the control force, the control torque, the flow field force and the flow field torque to which the underwater vehicle is subjected at the current moment;

[0171] An updating module 730, configured to update the first posture based on the second posture until the deviation between the updated first posture and the target posture is within a preset range;

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

[0173] The underwater vehicle closed-loop motion control simulation device integrated with CFD provided in the embodiment of the present application calculates the flow field force and flow field torque applied to the underwater vehicle at the current moment according to the position and posture of the underwater vehicle at the previous moment; and performs control simulation on the underwater vehicle in combination with the control force and control torque required at the current moment, so that its position and posture at the next moment change. The position and posture of the underwater vehicle at the previous moment are updated by the position and posture of the underwater vehicle at the next moment, and the next time step is solved, and this cycle is repeated until the deviation between the updated position and the target position and posture is within a preset range, so as to realize accurate simulation and real-time feedback of the navigation motion of the underwater vehicle, significantly improve the control accuracy, and be closer to the actual operation process, providing important support for the parameter adjustment and control method verification of the actual underwater vehicle.

[0174] It can be understood that the detailed functional implementation of each of the above-mentioned units / modules can be found in the introduction of the aforementioned method embodiment, and will not be repeated here.

[0175] It should be understood that the above-mentioned device is used to execute the method in the above-mentioned embodiment. The implementation principle and technical effect of the corresponding program module in the device are similar to those described in the above-mentioned method. The working process of the device can refer to the corresponding process in the above-mentioned method, which will not be repeated here.

[0176] Based on the method in the above embodiment, the present application embodiment provides an electronic device, see Figure 8 The electronic device may include: a processor (Processor) 810, a communication interface (Communications Interface) 820, a memory (Memory) 830 and a communication bus 840, wherein the processor 810, the communication interface 820, and the memory 830 communicate with each other through the communication bus 840. The processor 810 may call the logic instructions in the memory 830 to execute the method in the above embodiment.

[0177] In addition, the logic instructions in the above-mentioned memory 830 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform 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, which stores a computer program. When the computer program runs on a processor, the processor executes 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, the processor executes the method in the above embodiment.

[0180] It is understandable that the processor in the embodiment of the present application may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA) 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 can be implemented by hardware or by a processor executing software instructions. The software instructions can be composed of corresponding software modules, and the software modules can be stored in random access memory (RAM), flash memory, read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), registers, hard disks, mobile hard disks, CD-ROMs, or any other form of storage medium known in the art. An exemplary storage medium is coupled to a processor so that the processor can read information from the storage medium and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and the storage medium can 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 process or function described in the embodiment of the present application is generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium or transmitted through the computer-readable storage medium. The computer instructions may be transmitted from a website site, a computer, a server or a data center to another website site, a computer, a server or a data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium may be any available medium that a computer can access or a data storage device such as a server or a data center that includes one or more available media integrated. The available medium may be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state drive (SSD)), etc.

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

[0184] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A closed-loop motion control simulation method for underwater vehicles integrating CFD, It is characterized in that Applied to simulation software, including: According to the deviation between the first posture of the underwater vehicle at the previous moment and the target posture, the control force and control torque required by the underwater vehicle at the current moment are obtained; Obtaining a second posture of the underwater vehicle at a next moment according to the control force, the control torque, and the flow field force and flow field torque to which the underwater vehicle is subjected at a current moment; Updating the first posture based on the second posture until a deviation between the updated first posture and the target posture is within a preset range; Based on the flow field force, flow field force, flow field moment, control force, control moment and multi-degree-of-freedom motion equations of the underwater vehicle at each moment, control simulation of the underwater vehicle is performed.

2. The underwater vehicle closed-loop motion control simulation method integrating CFD as claimed in claim 1, It is characterized in that Applied to the simulation software, the flow field forces and flow field moments to which the underwater vehicle is subjected at the current moment include: Calculate the flow field force and the flow field moment based on the following formula; f fluid =S f p f a f -S f t f a f ; n fluid =∑ f [r f ×(p f a f )]-∑ f [r f ×(t f a f )]; In the formula, f fluid is the flow field force, f is the surface of the underwater vehicle, and 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 moment, r f is the distance vector from the center of mass of the underwater vehicle to the center of the surface.

3. The underwater vehicle closed-loop motion control simulation method integrating CFD as claimed in claim 2, It is characterized in that Applied to simulation software, the local pressure on the surface is obtained by: The local pressure is calculated based on the following formula: Wherein, df is a tiny face 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: Where x, y and z represent the horizontal, vertical and vertical axes of the Cartesian coordinate system, μ is the dynamic viscosity, ρ is the fluid density, u is the velocity vector field of the fluid, and u x 、u y and u z represent the velocity components of the fluid in the horizontal, vertical and vertical directions respectively, X, Y and Z are the mass force components of the fluid in the horizontal, vertical and vertical directions respectively, and t is the previous moment.

4. The underwater vehicle closed-loop motion control simulation method integrating CFD as claimed in claim 1, It is characterized in that Applied to simulation software, the method of obtaining the required control force and control torque of the underwater vehicle at the current moment according to the deviation between the first posture of the underwater vehicle at the previous moment and the target posture includes: Based on the following formula, the control force is obtained; Where τ is the control force, e d (t) is the first deviation between the first position in the first posture at the previous time t and the target position in the target posture, K p is the proportionality coefficient, T i is the integration time constant, T d is the differential time constant, t+1 is the current moment; Based on the following formula, the control torque is obtained; In the formula, τ θ is the control torque, e θ (t) is a second deviation between the first posture in the first posture at the previous time t and the target posture in the target posture.

5. The underwater vehicle closed-loop motion control simulation method integrating CFD as claimed in claim 1, It is characterized in that Applied to simulation software, the method of obtaining a second posture of the underwater vehicle at a next moment according to the control force, the control torque, the flow field force and the flow field torque to which the underwater vehicle is subjected at the current moment comprises: 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; Based on the angular velocity and the velocity of the center of mass, acquiring the second posture; The multi-degree-of-freedom motion equation of the underwater vehicle is specifically: Wherein, m is the sum of the mass of the underwater vehicle and the additional mass of the underwater vehicle, v is the velocity of the center of mass of the underwater vehicle, and f is fluid is the flow field force, f c is the external force generated by the multi-body constraint or joint, τ is the control force, t+1 is the current moment, M is the moment of inertia tensor, ω is the angular velocity of the underwater vehicle, and n fluid is the flow field moment, n c is the external torque generated by the multibody constraints or joints, τ θ is the control torque.

6. The underwater vehicle closed-loop motion control simulation method integrating CFD as claimed in claim 5, It is characterized in that Applied to simulation software, the step of obtaining the second posture based on the angular velocity and the velocity of the center of mass includes: Based on the following formula, the second posture is calculated; Z d1 (t+2)=Z d1 (t+1)+v x Δt; Z d2 (t+2)=Z d2 (t+1)+v y Δt; Z d3 (t+2)=Z d3 (t+1)+v z Δt; Z θ1 (t+2)=Z θ1 (t+1)+ω x Δt; Z θ2 (t+2)=Z θ2 (t+1)+ω y Δt; Z θ3 (t+2)=Z θ3 (t+1)+ω z Δt; In the formula, Z d1 , Z d2 and Z d3 are the position components of the second position in the second posture in the horizontal, longitudinal and vertical directions 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 mass center in the horizontal, longitudinal and vertical directions, respectively, Z θ1 , Z θ2 and Z θ3 are the rotation angle components of the second posture in the second posture in the horizontal axis direction, the longitudinal axis direction and the vertical axis direction respectively, ω x ,ω y and ω z are the angular velocity components of the underwater vehicle in the horizontal, longitudinal and vertical directions respectively, and Δt is the interval between the next moment and the current moment.

7. A closed-loop motion control simulation device for underwater vehicles integrating CFD, It is characterized in that include: A first acquisition module, used for acquiring the control force and control torque required by the underwater vehicle at the current moment according to the deviation between the first posture of the underwater vehicle at the previous moment and the target posture; A second acquisition module, used for acquiring a second posture of the underwater vehicle at a next moment according to the control force, the control torque, and the flow field force and flow field torque to which the underwater vehicle is subjected at a current moment; An updating module, configured to update the first posture based on the second posture until a deviation between the updated first posture and the target posture is within a preset range; The control module is used to perform control simulation on the underwater vehicle based on the flow field force, flow field force, flow field moment, control force, control moment and multi-degree-of-freedom motion equations of the underwater vehicle at each moment.

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

9. A computer-readable storage medium storing a computer program. It is characterized in that When the computer program runs on a processor, the processor executes the underwater vehicle closed-loop motion control simulation method integrating CFD as described in any one of claims 1 to 6.

10. A computer program product, It is characterized in that When the computer program product runs on a processor, the processor executes the underwater vehicle closed-loop motion control simulation method integrating CFD as described in any one of claims 1 to 6.

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