CN-121997719-A - Amphibious unmanned platform hydrodynamic coefficient identification method based on genetic algorithm

CN121997719ACN 121997719 ACN121997719 ACN 121997719ACN-121997719-A

Abstract

The invention discloses a genetic algorithm-based amphibious unmanned platform hydrodynamic coefficient identification method, which comprises the steps of establishing an amphibious platform hydrodynamic model, determining hydrodynamic coefficients, and carrying out an amphibious platform CFD simulation experiment to obtain data of motion states, received hydrodynamic forces and moments. Constructing an objective function and an adaptability function according to simulation experiment data, and optimizing the objective function by adopting a genetic algorithm. Compared with the traditional dynamics model, the invention carries out quantitative research on the asymmetry of the hydrodynamic coefficient caused by the asymmetry of the geometric shape of the amphibious platform, establishes a novel dynamics model suitable for the amphibious platform, and predicts the motion performance and hydrodynamic performance of the amphibious platform more accurately. In addition, the invention does not need to carry out model experiments, greatly reduces the experiment cost and shortens the experiment period.

Inventors

CHEN CAN
SHI YAN
ZHANG FANSHENG
QIAN MIN
YANG ZI

Assignees

南京理工大学
南京理工大学淮安研究院

Dates

Publication Date: 20260508
Application Date: 20260105

Claims (9)

1. The amphibious unmanned platform hydrodynamic coefficient identification method based on the genetic algorithm is characterized by comprising the following steps of: s1, establishing an amphibious platform hydrodynamic model and determining a hydrodynamic coefficient; S2, performing CFD simulation experiments of the amphibious platform to obtain data of a motion state and received hydrodynamic force and moment; S3, constructing an objective function and an adaptability function according to simulation experiment data; and S4, optimizing the objective function by adopting a genetic algorithm to obtain the hydrodynamic coefficient value.
2. The method for identifying the hydrodynamic coefficient of the amphibious unmanned platform based on the genetic algorithm of claim 1, wherein in the step S1, an inertial coordinate system and a satellite coordinate system are established for the amphibious platform, wherein the satellite coordinate system takes the mass center of the amphibious platform as an origin; the amphibious platform performs six-degree-of-freedom motion during underwater diving, and comprises linear motion along three coordinate axes of a satellite coordinate system and rotation motion around three axes.
3. The method for identifying the hydrodynamic coefficients of the amphibious unmanned platform based on the genetic algorithm according to claim 2, wherein in the step S1, three components of external force applied to the platform on a satellite coordinate system are respectively X, Y and Z, three components of external force moment applied to the platform are K, M and N, and a general equation of the stressed motion of the amphibious platform is obtained according to a rigid motion theorem and an inertia moment theorem: ; Wherein m is the mass of the amphibious platform, I x ,I y ,I z is the moment of inertia of the platform to the three axes of the satellite coordinate system, u, v, w, p, q, r is the six-degree-of-freedom speed in the satellite coordinate system with the mass center of the amphibious platform as the origin, Indicating acceleration.
4. The method for identifying the hydrodynamic coefficients of the amphibious unmanned platform based on the genetic algorithm according to claim 2, wherein in the step S1, the hydrodynamic force F H received by the amphibious platform can be divided into inertial hydrodynamic force related to acceleration and viscous hydrodynamic force related to speed, and the viscous hydrodynamic force model and the inertial hydrodynamic force model of the amphibious platform are: ; 。
5. The method for identifying the hydrodynamic coefficients of the amphibious unmanned platform based on the genetic algorithm of claim 4, wherein the viscous hydrodynamic force is also expressed as: 。
6. The method for identifying the hydrodynamic coefficient of the amphibious unmanned platform based on the genetic algorithm of claim 1, wherein in the step S1, the hydrodynamic force applied to the amphibious unmanned platform can be calculated according to the hydrodynamic model under the condition that the six-degree-of-freedom speed and the acceleration of the amphibious platform are known according to the hydrodynamic model. When the amphibious platform is required to reach a specific motion state, the aim of controlling the motion state of the amphibious platform can be achieved by applying corresponding force and moment to the amphibious platform.
7. The genetic algorithm-based amphibious unmanned platform hydrodynamic coefficient identification method is characterized in that in step S2, simple harmonic motion simulation experiments of the amphibious platform in the directions of direct navigation, oblique navigation and six degrees of freedom are conducted, simulation experiment hydrodynamic force and moment experiment data are obtained, and the simulation experiments are achieved through CFD software STAR CCM+.
8. The method for identifying the hydrodynamic coefficient of the amphibious unmanned platform based on the genetic algorithm according to claim 1, wherein in the step S3, an objective function and an fitness function are constructed according to simulation experiment data, and in N times of simulation experiments, the square sum of residuals between a simulation experiment value Fm and a theoretical calculation value F is expressed as the objective function: ; Wherein J is an objective function, F mi represents an ith simulation experiment value, and F i represents an ith theoretical calculation value; constructing a fitness function according to the objective function J: , Wherein F is the fitness function, In order to prevent the overflow amount from being exceeded, =0.001。
9. The method for identifying the hydrodynamic coefficients of the amphibious unmanned platform based on the genetic algorithm according to claim 1, wherein in the step S4, the method is realized by the following steps: 1) Setting the size M of the population, the upper limit of the iteration times, the crossover probability and the variation probability, establishing an initial gene library of the population, and performing binary coding on all individuals in the population; 2) Calculating the fitness of all individuals, and selecting the individuals according to the fitness as the inherited probability; 3) Determining whether to cross according to the cross probability; 4) Determining whether to mutate according to the mutation probability; 5) Obtaining a new population after cross mutation, and carrying out genetic iteration; 6) Decoding the individual with the maximum adaptability to obtain the optimal individual, namely the hydrodynamic coefficient value.

Description

Amphibious unmanned platform hydrodynamic coefficient identification method based on genetic algorithm Technical Field The invention belongs to the technical field of underwater vehicles, and particularly relates to an amphibious unmanned platform hydrodynamic coefficient identification method based on a genetic algorithm. Background The amphibious unmanned platform is increasingly researched, and relates to the aspects of technical innovation, intelligent development, multifunctional application and the like. The platforms have potential in the fields of ocean scientific research, water area detection, disaster relief and the like. In the research and application fields of the underwater unmanned platform, the accurate dynamic model is not only helpful for deep understanding of the dynamic characteristics of the unmanned platform, but also can provide support for the development process of the control algorithm and help to make an accurate decision. And hydrodynamic coefficients are parameters describing hydrodynamic effects to which an object is subjected when moving in water. These coefficients are typically used to build a hydrodynamic model to predict the motion behavior of an object in water. Hydrodynamic coefficients include viscous hydrodynamic coefficients and inertial hydrodynamic coefficients, which are closely related to factors such as the geometry of the object, fluid properties, motion state, etc. The method for identifying hydrodynamic coefficients is various and comprises restraint model experiments, CFD calculation and system identification methods. The constrained model experiment obtains hydrodynamic coefficients by testing the model in a pool or a water tunnel and measuring the motion parameters of an object under different conditions. CFD calculation is to simulate the action of water flow on an object by using a computational fluid dynamics technology so as to determine a hydrodynamic coefficient. The system identification rule is based on the physical law and the mathematical model, and the estimated value of the hydrodynamic coefficient is obtained through deduction and analysis. The test method is the most reliable way to obtain the hydrodynamic coefficient after the physical design is finished, but the method generally has the limitations of long preparation period, higher cost and the like, so that the method is limited in wide application, and compared with the traditional test method, the method can greatly shorten the test period while ensuring the data precision by utilizing numerical calculation. The CFD method not only can accurately acquire the force and the moment born by the underwater vehicle in the motion process, but also can realize high-fidelity analysis of surrounding flow field structures, thereby providing an important numerical analysis basis for the appearance design, performance evaluation and autonomous control of the underwater vehicle. Disclosure of Invention The invention solves the technical problem of providing a novel dynamic model suitable for an amphibious platform, and the model is more accurate in forecasting the motion performance and hydrodynamic performance of the amphibious platform. The technical scheme adopted by the invention is as follows in order to solve the technical problems: An amphibious unmanned platform hydrodynamic coefficient identification method based on a genetic algorithm comprises the following steps: s1, establishing an amphibious platform hydrodynamic model and determining a hydrodynamic coefficient; and S2, carrying out CFD simulation experiments of the amphibious platform to obtain data of the motion state, the received hydrodynamic force and the received moment. And S3, constructing an objective function and an adaptability function according to simulation experiment data. And S4, optimizing the objective function by adopting a genetic algorithm to obtain the hydrodynamic coefficient value. Further, in step S1, an inertial coordinate system and a satellite coordinate system are established for the amphibious platform, wherein the satellite coordinate system uses the centroid of the amphibious platform as an origin; the amphibious platform performs six-degree-of-freedom motion during underwater diving, and comprises linear motion along three coordinate axes of a satellite coordinate system and rotation motion around three axes. Further, in step S1, a general equation of the stressed motion of the amphibious platform is obtained according to the rigid motion theorem and the moment of inertia theorem: ; wherein m is the mass of the amphibious platform, I x,Iy,Iz is the moment of inertia of the platform to the three axes of the satellite coordinate system, u, v, w, p, q and r are the six-degree-of-freedom speeds of the satellite coordinate system with the mass center of the amphibious platform as the origin. Further, in step S1, the hydrodynamic force F H received by the amphibious platform may be divided into an inertial hyd