CN-116541951-B - Ship thrust distribution method based on improved aigrette algorithm

CN116541951BCN 116541951 BCN116541951 BCN 116541951BCN-116541951-B

Abstract

The invention discloses a ship thrust distribution method based on an improved fish algorithm, which comprises the following steps of establishing a three-degree-of-freedom mathematical model and an interference model of the mathematical model of a ship, obtaining power, torque and thrust models of a ship propeller according to the three-degree-of-freedom mathematical model and the interference model of the mathematical model and by combining hydrodynamic characteristic analysis of a propeller, establishing a ship thrust target distribution function according to energy consumption of the propeller, abrasion of the propeller and instruction errors, optimizing propeller parameters based on a global artificial fish algorithm, obtaining a relative optimal parameter solving domain for enabling the ship thrust target distribution function to be minimum, and re-optimizing the relative optimal parameter solving domain through the Egre algorithm, so as to obtain a final relative optimal solution of the propeller parameters. The method solves the problems that the control precision of the ship is greatly affected by the selection of the existing thrust distribution method, and the abrasion and energy consumption of the propeller cannot be effectively reduced on the basis of ensuring the control precision.

Inventors

WANG SHASHA
LIN JIANLONG
PENG ZHOUHUA
TUO YULONG
LIU YUXIN
LI JIALIANG

Assignees

大连海事大学

Dates

Publication Date: 20260505
Application Date: 20230323

Claims (7)

1. The ship thrust distribution method based on the improved aigrette algorithm is characterized by comprising the following steps of: Step S1, establishing a mathematical model with three degrees of freedom of a ship and an interference model of the mathematical model; the three-degree-of-freedom mathematical model comprises a ship kinematics model and a ship dynamics model; the interference model comprises a sea wind model, a sea wave model and a sea current model; S2, according to the three-degree-of-freedom mathematical model and an interference model of the mathematical model, combining with hydrodynamic characteristic analysis of the propeller to obtain power, torque and thrust models of the ship propeller; Step S3, obtaining the energy consumption of the propeller according to the power, torque and thrust model of the ship propeller; establishing a ship thrust target distribution function according to the energy consumption of the propeller, the abrasion of the propeller and the instruction error; Step S4, optimizing propeller parameters based on a global artificial fish swarm algorithm, and obtaining a plurality of relative optimal parameter solving domains for enabling a ship thrust target distribution function to be minimum; the propeller parameters comprise the azimuth angle of the propeller and the thrust of the propeller; s5, re-optimizing the relative optimal parameter solving domain through an aigrette algorithm to obtain a final relative optimal solution of propeller parameters; the final relative optimal solution is used as the final azimuth angle and thrust of the propeller.
2. The ship thrust distribution method based on the modified aigrette algorithm according to claim 1, wherein the three degrees of freedom mathematical model and the interference model of the mathematical model in step S1 are specifically: the ship kinematic model is that Representing the attitude and position functions of the ship in the north-east coordinate system; representing the attitude angle of the ship in the north-east coordinate system; Representing a three-dimensional Euclidean torus; a function representing the attitude and position of the ship; representing the speed of the ship; a rotation matrix representing the attitude angle of the ship; A zero matrix representing three rows and three columns; Representing an angular velocity rotation matrix; the ship dynamics model is that Wherein: Representing an inertial matrix of the hydrodynamic system, and correlating linear acceleration and angular acceleration of the ship; representing a hydrodynamic coriolis centripetal force matrix and relating to an additional mass of the vessel; representing that the hydrodynamic damping coefficient matrix contains linear damping terms Nonlinear damping term ; Restoring force caused by buoyancy of the ship; Restoring force provided for vessel ballasting; Is an environmental disturbance; Is the theoretical thrust of the propeller.
3. The ship thrust distribution method based on the improved aigrette algorithm according to claim 1, wherein the power, torque and thrust efficiency model of the ship propeller is obtained in step S2, specifically: Step S2.1, the thrust and the torque of the propeller are defined as the following functional forms; wherein: Representing the thrust of the propeller; Representing propeller torque; Indicating the rotation speed; representing a fixed parameter; representing a time-varying parameter; Step S2.2, converting the functional form into a specific propeller thrust and torque expression as follows: wherein: And (3) with Respectively representing a thrust coefficient and a torque coefficient; Represents sea water density; Represents the propeller diameter; step S2.3, according to the torque expression of the propeller, the calculation formula of the consumption power of the propeller is obtained as follows: Step S2.4, obtaining the relation between the consumption power and the thrust of the propeller according to the calculation formulas of the step S2.2 and the step S2.3, wherein the relation is as follows: 。
4. The method for distributing ship thrust based on the modified aigrette algorithm according to claim 1, wherein in step S3, a ship thrust target distribution function is established according to the energy consumption of the propeller, the wear of the propeller and the instruction error, and the calculation formula is Wherein: an energy function representing a ship thrust target distribution function; Representing the thrust of the propeller; representing azimuth angles of each propeller in the current allocation period; Representing the weight coefficient; represent the first Power consumption of the table propeller; representing the correction coefficient; represent the first Thrust of the table propeller; Representing the sum of the power consumption of all the propellers; is a relaxation variable matrix; relaxing the transpose of the variable matrix; And (3) with Representing a positive definite diagonal matrix; indicating the azimuth angle of each propeller in the previous period; a transposition of azimuth differences between each propeller in the current allocation period and each propeller in the previous period is represented; representing a propeller configuration matrix; is the theoretical thrust of the propeller; representing a power change limit term; Representing the actual propeller power rate of change; is the desired rate of change of propeller power; representing a matrix of weight coefficients.
5. The ship thrust distribution method based on the modified aigrette algorithm according to claim 1, wherein in step S4, a plurality of relatively optimal parameter solving domains for minimizing a ship thrust target distribution function are obtained, specifically: S4.1, randomly initializing fish shoals in a relative optimal parameter solving domain based on a global artificial fish shoal algorithm to form a plurality of initial artificial fish shoals, wherein artificial fish individuals in each initial artificial fish shoal represent a ship thrust target distribution function, and a group of solutions of thrust of a propeller and azimuth angle of the propeller are formed; the global artificial fish swarm algorithm initialization parameter comprises the number of artificial fish individuals Initial state of each artificial fish Number of iterations Number of attempts Factor of degree of congestion Preset value of jumping behavior 、 Threshold of swallowing behaviour ; S4.2, calculating a corresponding ship thrust target distribution function value according to the current state of each artificial fish, initializing the artificial fish state corresponding to the minimum value of the ship thrust target distribution function to be the optimal artificial fish state, and recording the maximum moving step length of each artificial fish And vision And outputs the current optimal solution Writing to a bulletin board; step S4.3, judging whether the preset iteration times are met If yes, outputting the current optimal solution on the bulletin board If not, executing the steps S4.4 to S4.6; Step S4.4, initializing the maximum moving step length of each artificial fish in the artificial fish swarm And vision ; S4.5, evaluating the behavior of each artificial fish according to foraging behavior, clustering behavior, rear-end collision behavior and random behavior, and selecting the optimal behavior from the behaviors to execute and update the state of the artificial fish; Step S4.6 current optimal solution Performing an annealing operation to determine whether the temperature is less than a temperature threshold Outputting the solution if yes, otherwise, reducing the temperature and continuing annealing until the temperature is less than the temperature threshold ; Step S4.7, the current optimal solution obtained by each artificial fish swarm is calculated Is set as a relatively optimal parameter solving domain.
6. The method for distributing ship thrust based on the modified aigrette algorithm according to claim 5, wherein said foraging behavior in step S4.5 is specifically set to be the first one The current state of the artificial fish is First, the The strip artificial fish is in the field of view Internal random selection of a new state And (2) and If (1) I.e. state Is superior to The current state of the artificial fish Directional state Moving by one step; If it is The state is reselected Making an attempt to reach a preset attempt Still unable to move after the times, then the artificial fish is further forward at random, and the random behavior formula is as follows: wherein: Representing the status Is provided; Representing the status Is provided; Representation of Artificial fish state at moment; Representation of Artificial fish state at moment; Representing a step size; A random number representing the [0,1] interval; The clustering behavior is specifically that in the first step Current state of artificial fish Visual field In the search for the number of individuals gathering fish shoals With the central position of the gathering fish shoal ; Wherein: Representing the state of the artificial fish; representing a plurality of states of the artificial fish; If the condition is satisfied The current state of the artificial fish Toward the center of the gathering fish shoal Moving by one step: Otherwise, executing foraging behavior; wherein: Representing a congestion degree factor; propeller power consumption representing a center position; Representation of Artificial fish state at moment; Representation of Artificial fish state at moment; Representing a step size; A random number representing the [0,1] interval; The rear-end collision behavior is specifically that in the first step Condition of artificial fish Is searched for optimal artificial fish partner in the field , Representing a minimum value of power consumption of the propeller; If the condition is satisfied The current state of the artificial fish Will face towards Is shifted by one step; wherein: Representation of Artificial fish state at moment; Representation of Artificial fish state at moment; Representing a step size; A random number representing the [0,1] interval; Representing the status Is provided; Representing a congestion degree factor; Indicating the number of individuals gathering the fish school, otherwise, executing foraging behavior.
7. The ship thrust distribution method based on the improved aigrette algorithm according to claim 1, wherein in step S5, the relative optimal parameter solving domain is re-optimized by aigrette algorithm, specifically S5.1, taking the obtained relative optimal parameter solving domain propeller thrust and propeller azimuth as thrust distribution decision variables of a mathematical model of a ship thrust target distribution function; coding the decision variables of the thrust distribution into individuals of an aigrette group to obtain a coded mathematical model, wherein the aigrette group comprises a plurality of aigrette teams consisting of aigrette group individuals; S5.2, constructing an aigrette optimization algorithm taking aigrette sitting and other strategies, aggressive strategies and iteration times as topics; The calculation formula of the sitting strategy is that Wherein: representing the position of the aigrette individual after iteration; Representing the position of the aigrette individual after the last iteration; representing an exponential function; Representing the iteration number; A maximum value representing the number of iterations; A feasible region range representing an argument; Represented as a gradient; The aggressive strategy comprises a random walk and surrounding mechanism, and the aigrette individual updating position formula of the random walk is as follows Wherein: representing the position of the aigrette individual after iteration; Representing the position of the aigrette individual after the last iteration; Representing a random number; Representing the iteration number; A feasible region range representing an argument; the aigrette individual update location formula of the surrounding mechanism is as follows Wherein: representing the difference between the optimal value of the aigrette and the current aigrette individual position; Representing the difference value between the optimal value of the aigrette group and the current aigrette individual position; 、、 Representation of Random numbers in between; representing the optimal value of the aigrette; representing the optimal value of aigrette population; s5.3, updating optimal solutions of the sitting strategy and the aggressive strategy, wherein the optimal solutions are aigrette individual positions which enable the coded mathematical model value to be minimum; s5.4, comparing the fitness of the updated aigrette individual position with the fitness of the aigrette individual position of the last iteration; if the adaptation degree of the updated aigrette individual position is superior to that of the aigrette individual position of the last iteration, adopting the updated aigrette individual position, otherwise, abandoning the updating until the maximum iteration number is reached; S5.5, performing aigrette individual decoding on the aigrette individual position obtained after the maximum iteration number to obtain a thrust distribution decision variable of a mathematical model of a ship thrust target distribution function; and realizing the distribution of the ship thrust by the obtained thrust distribution decision variable.

Description

Ship thrust distribution method based on improved aigrette algorithm Technical Field The invention relates to the field of ship thrust distribution, in particular to a ship thrust distribution method based on an improved aigrette algorithm. Background The sea area with nearly three million square kilometers in China is a coastal country, so that more importance is attached to the development and utilization of the ocean, including the development of offshore oil and natural gas, mineral collection, aquatic fishing and the like. However, the development difficulty of ocean resources is much greater than that of land resources, so that positioning systems are used, and the existing positioning systems are mainly divided into two types, namely a dynamic positioning system and an anchoring positioning system. The traditional anchoring positioning system has simple and reliable structure, and does not need a propeller to resist the interference of external environment, so that the energy consumption can be reduced, and the economical efficiency is good. However, when the submarine space is insufficient to accommodate more anchors and the operation water depth is continuously increased, the dynamic positioning system is the only choice, and has very high positioning precision, so that the whole operation process and the safety of operators can be effectively ensured. Dynamic positioning systems refer to systems that utilize the propulsion unit of the vessel itself and automatically maintain position and heading through the action of a controller. And three equipment levels are defined, the positioning disorder can occur under the single fault condition, the positioning disorder can not occur when the active component has single fault, and the positioning disorder can not occur when any component and system have single fault (including the fault caused by the fire or flood of the isolation cabin). The most important of the dynamic positioning system is a thrust distribution system, wherein the thrust distribution is also an important component of the dynamic positioning control system and is responsible for reasonably distributing the three-degree-of-freedom control force output by the controller to the execution mechanism on the ship according to a certain distribution strategy. However, the existing thrust distribution method has a great influence on the control accuracy of the ship, and the abrasion and energy consumption of the propeller cannot be effectively reduced on the basis of ensuring the control accuracy. Disclosure of Invention The invention provides a ship thrust distribution method based on an improved aigrette algorithm, which aims to solve the problems that the control precision of a ship is greatly influenced by the selection of the existing thrust distribution method, and the abrasion and energy consumption of a propeller cannot be effectively reduced on the basis of ensuring the control precision. In order to achieve the above object, the technical scheme of the present invention is as follows: a ship thrust distribution method based on an improved aigrette algorithm comprises the following steps: Step S1, establishing a mathematical model with three degrees of freedom of a ship and an interference model of the mathematical model; the three-degree-of-freedom mathematical model comprises a ship kinematics model and a ship dynamics model; the interference model comprises a sea wind model, a sea wave model and a sea current model; S2, according to the three-degree-of-freedom mathematical model and an interference model of the mathematical model, combining with hydrodynamic characteristic analysis of the propeller to obtain power, torque and thrust models of the ship propeller; Step S3, obtaining the energy consumption of the propeller according to the power, torque and thrust model of the ship propeller; establishing a ship thrust target distribution function according to the energy consumption of the propeller, the abrasion of the propeller and the instruction error; Step S4, optimizing propeller parameters based on a global artificial fish swarm algorithm, and obtaining a plurality of relative optimal parameter solving domains for enabling a ship thrust target distribution function to be minimum; the propeller parameters comprise the azimuth angle of the propeller and the thrust of the propeller; s5, re-optimizing the relative optimal parameter solving domain through an aigrette algorithm to obtain a final relative optimal solution of propeller parameters; the final relative optimal solution is used as the final azimuth angle and thrust of the propeller. Further, the three degrees of freedom mathematical model and the interference model of the mathematical model in step S1 are specifically: the ship kinematic model is that Representing the attitude and position functions of the ship in the north-east coordinate system, Θ= [ phi theta phi ] T∈S3 representing the attitude angle of the ship in the