A method for optimizing and adjusting degaussing current in a distributed degaussing system

Abstract

The invention discloses a method for optimizing and adjusting the demagnetization current of a distributed demagnetization system. The method comprises the following steps: searching for the flight speed and position of an individual, and calculating the fitness function value of each individual at the current position; for each individual, comparing the fitness function value of the current position with the fitness function value of the current individual historical optimal position, and determining the current individual historical optimal position; for all individuals, comparing the fitness function value of the current individual historical optimal position of each individual with the fitness function value of the current global historical optimal position, and determining the current global historical optimal position; judging whether a termination condition is met according to the current global historical optimal position, and terminating the adjustment of the demagnetization current if the demagnetization current corresponding to the current global historical optimal position reaches a preset value; the invention optimizes the calculation algorithm, simplifies the calculation procedure, and shortens the calculation time, so as to minimize the peak error of the residual magnetic field after the ship is demagnetized.

Description

Technical Field

[0001] The invention belongs to the technical field of ship demagnetization, and in particular relates to a demagnetization current optimization adjustment method for a distributed demagnetization system. Background Art

[0002] Naval ships are generally equipped with active degaussing systems, the purpose of which is to compensate for the ship's magnetic field and reduce the risk of the ship being attacked by underwater weapons. In order to maximize the role of the active degaussing system, the ampere-turns of the degaussing coil must be optimized and adjusted to make the compensated ship's magnetic field as small as possible. The number of turns of the degaussing coils in the distributed degaussing system is fixed, and the vertical magnetic field peak at a certain depth below the ship is reduced to a specified limit mainly by adjusting the current of each degaussing coil.

[0003] In the early days, the ship demagnetization current optimization adjustment method determined the ship's magnetic field characteristics, consulted the coil demagnetization effect manual, selected the coil or coil combination that produced the closest peak value of the ship's existing magnetic field, and adjusted its current and number of turns to compensate for the ship's magnetic field. However, this method is limited to adjusting one or a few coils at a time. As the number of demagnetization coils increases, this method becomes increasingly difficult to implement. In recent decades, another demagnetization current optimization adjustment method has been used in laboratory research work. This method uses a computer to fit the magnetic field characteristics of all demagnetization coils to the magnetic field characteristics of the ship using the least squares algorithm. This method can better compensate for the ship's magnetic field, but this method is limited to minimizing the root mean square error of the residual magnetic field after the ship is demagnetized, and cannot minimize the peak error of the residual magnetic field. In recent years, genetic algorithms have been used in the optimization adjustment of demagnetization current in distributed demagnetization systems, which can minimize the peak error of the ship's residual magnetic field. However, genetic algorithms run slowly, are complex to implement, and require too many parameters to be adjusted, making them difficult to implement. Summary of the invention

[0004] In view of this, the present invention provides a method for optimizing and adjusting the demagnetization current of a distributed demagnetization system to optimize the calculation algorithm, simplify the calculation procedure, shorten the calculation time, and minimize the peak error of the residual magnetic field after ship demagnetization.

[0005] The present invention is achieved through the following technical solutions:

[0006] A distributed degaussing system degaussing current optimization adjustment method, the degaussing current of each degaussing coil is regarded as an individual without mass and volume, and all individuals form a group; each individual has its own flight speed, position and fitness value determined by the fitness function, the flight speed is the step length of the degaussing current change, and the position is the current value of the degaussing current changing with the step length;

[0007] The specific steps of the demagnetization current optimization adjustment method are as follows:

[0008] Step 1: Initialize the position and flight speed of the individual, and use the initial position as the current individual historical optimal position. Then compare the individual historical optimal positions of each individual to find the global historical optimal position at the initial time.

[0009] Step 2: Search the flight speed and position of the individual, and calculate the flight speed of each individual i at the current position X i The fitness function f(X i )value;

[0010] Step 3: For each individual i, the current position X i The fitness function f(X i ) value and the current individual historical optimal position P i The fitness function f(P i ) values, if f(X i )<f(P i ), then the individual's current position X i As the current individual historical optimal position P i ; If f(X i )≥f(P i ), then the individual's current individual historical optimal position P i remain unchanged;

[0011] Step 4: For all individuals, the current individual historical optimal position P of each individual i is i The fitness function f(P i ) values ​​are respectively related to the current global historical optimal position P g The fitness function f(P g ) values, if f(P i )<f(P g ), then the individual's current individual historical optimal position P i As the current global historical optimal position P g ; If f(P i )≥f(P g ), then the current global historical optimal position P g remain unchanged;

[0012] Step 5: According to the current global historical optimal position P obtained in step 4 g , to determine whether the termination condition is reached. If the current global historical optimal position P g The corresponding demagnetization current reaches the preset value, then the adjustment of the demagnetization current ends; if the previous global historical optimal position P g If the corresponding demagnetization current does not reach the preset value, repeat steps 2 to 5 for iterative calculation until the current global historical optimal position P gWhen the corresponding demagnetization current reaches a preset value or reaches a preset maximum number of iterations, the adjustment of the demagnetization current is terminated.

[0013] Furthermore, let the number of individuals in the population be N; the dimension of each individual be D; the current position of individual i be X i =(x i1 , x i2 , ..., x iD ); the current flight speed of individual i is V i =(v i1 , v i2 , ..., v iD );The individual historical optimal position P of individual i i =(p i1 , p i2 , ..., p iD );

[0014] In step 3, the current individual historical optimal position P of individual i in the tth generation i (t) is determined by the following formula:

[0015]

[0016] Furthermore, in step 4, the current global historical optimal position P of the entire population in the tth generation g (t) is determined by the following formula:

[0017] P g (t)={P1(t), P2(t),..., PN(t)}|f(P g (t))=min{f(P1(t)), f(P2(t)),..., f(PN(t))} (2).

[0018] Furthermore, let the number of individuals in the population be N; the dimension of each individual be D; the current position of individual i be X i =(x i1 , x i2 , ..., x iD ); the current flight speed of individual i is V i =(v i1 , v i2 , ..., v iD );The individual historical optimal position P of individual i i =(p i1 , p i 2, ..., p iD );

[0019] In step 2, the search formula v for the flight speed of individual i in the t+1th generation is ij(t+1) and the search formula for the position of individual i x ij (t+1) can be described as:

[0020] v ij (t+1)=v ij (t)+c1×r1 j (t)*(p ij (t)-x ij (t))+c2×r2 j (t)*(pg j (t)-x ij (t))(3)

[0021] x ij (t+1)=x ij (t)+v ij (t+1)(4)

[0022] Among them, the subscript "j" represents the j-th dimension of the individual; r1~U(0,1), r2~U(0,1) are two independent random functions; c1 and c2 are acceleration constants, which take values ​​between 0 and 2.

[0023] Furthermore, the position x of the individual i ij ∈[-x max , x max ], flight speed v ij ∈[-v max , v max ]; then v max =k×x max , k is a coefficient, with a value of 0.1≤k≤1.0, where x max is the maximum position, v max is the maximum speed.

[0024] Furthermore, the value of D is 1, 2, or 3.

[0025] Furthermore, the implementation process of the distributed degaussing system degaussing current optimization adjustment method is as follows:

[0026] The first step is to set the calculation program parameters;

[0027] The second step is to measure the original magnetic field of the ship:

[0028] The third step is to measure the winding efficiency of the degaussing coil;

[0029] The fourth step is to input the original magnetic field of the ship in the second step and the winding efficiency of the demagnetization coil in the third step as parameters into the program, and then start the program. The program will automatically perform optimization iterative calculations until the calculation results meet the termination conditions, and then output the optimal combination of demagnetization currents. The combination is an array, and each element in the array corresponds to the demagnetization current of a demagnetization coil. The demagnetization current value is set to the actual working current of the corresponding demagnetization coil, and the demagnetization system power supply is started. When all demagnetization coils are powered on at the same time, the magnetic field of the demagnetization coil will compensate for the ship's magnetic field, so that the peak error of the compensated ship's residual magnetic field is minimized.

[0030] Beneficial effects:

[0031] (1) The demagnetization current optimization adjustment method of the present invention is an optimization adjustment algorithm based on an iterative mode. The algorithm takes the minimum peak error of the residual magnetic field after ship demagnetization as the fitness function, and can obtain the global optimal solution. In addition, each step and parameter setting of the algorithm is specifically designed according to the characteristics of the demagnetization current adjustment of the ship demagnetization system, making the algorithm intuitive, simple to program, fast in convergence speed, short in calculation time, and can be easily applied to engineering practice.

[0032] (2) The data input of the iterative optimization algorithm in the adjustment method of the present invention adopts full numerical real number input, and the entire calculation process adopts full numerical operation. The calculation output result is more intuitive, and the output result can directly guide the optimization adjustment of the demagnetization current of the distributed demagnetization system.

[0033] (3) The implementation process of the adjustment method of the present invention includes setting calculation program parameters, measuring the original magnetic field of the ship, measuring the winding efficiency of the demagnetization coil and outputting the adjustment results. Through the operation of the above steps, the optimized demagnetization current combination of multiple demagnetization coils can be conveniently and quickly found, which can make the demagnetization current adjustment work faster, simpler and more effective, thereby achieving the purpose of rapid adjustment of the demagnetization current and effective compensation of the ship's magnetic field. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a diagram of the operation steps of the demagnetization current optimization adjustment algorithm of the present invention;

[0035] Figure 2 A flow chart for implementing the degaussing current optimization adjustment method for a distributed degaussing system. DETAILED DESCRIPTION

[0036] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0037] This embodiment provides a method for optimizing and adjusting the demagnetization current of a distributed demagnetization system. The method first sets the maximum adjustment range of the demagnetization current of each demagnetization coil according to the needs of the demagnetization system, and then regards the demagnetization current of each demagnetization coil as an individual without mass and volume in the optimization space, and all individuals form a group; each individual has its own flight speed, position and fitness value determined by the fitness function, and the flight speed and position determine the flight direction and distance of the individual, the flight speed is the step length of the demagnetization current change, and the position is the current value of the demagnetization current changing with the step length; the flight direction of the individual is the increase or decrease of the demagnetization current, and the distance is the current value of the increase or decrease of the demagnetization current; according to the current flight speed, position and fitness value determined by the fitness function of each individual, the current optimal value of each individual is calculated, and each individual memorizes and follows the current optimal value, and finally, the flight speed and final position of each individual are dynamically adjusted according to the comprehensive analysis results of the flight experience of the individual and the group;

[0038] The fitness value of each individual depends on the value of the selected fitness function, and each individual has the following three types of information: ① the current position of the individual; ② the optimal position P that the individual has experienced so far i ; ③ Up to the current position, the optimal position P experienced by all individuals in the entire group g (P g It is in P i The optimal value in the optimal position P i is regarded as the individual's own flight experience; the optimal position P g It can be regarded as the sharing of flight experience by the companions of the entire group; therefore, the flight speed of each individual is affected by the historical motion state information of itself and the group, and the historical optimal position of itself and the group is used to influence the current flight speed and position of the individual, which well coordinates the relationship between the individual's own movement and the group's movement.

[0039] Among them, the optimal position P experienced by all individuals in the entire group g The iterative optimization algorithm is as follows:

[0040] Assume that the number of individuals in the group is N; the dimension of each individual is D (because the ship's magnetic field is divided into fixed magnetic field, induced magnetic field and eddy current magnetic field, the demagnetization current in each demagnetization coil is divided into fixed current, induced current and eddy current. At this time, the individual dimension is three-dimensional, that is, D = 3. Sometimes the eddy current is not considered, and D = 2. Sometimes the fixed magnetic field is not compensated by the coil, that is, the fixed current is not considered, and D = 1. Therefore, the value of D is generally 1, 2, 3). Any individual in the group is individual i, i = 1, 2, 3, ... N; the current position of individual i is X i =(x i1 , xi2 , ..., x iD ); the current flight speed of individual i is V i =(v i1 , v i2 , ..., v iD ); the optimal position P experienced by individual i i =(p i1， p i2， ..., p iD ), that is, the position with the best fitness value experienced by individual i, is called the individual historical optimal position P i The optimal fitness value is determined by the fitness function, that is, the fitness function can minimize the peak error of the residual magnetic field after the ship is demagnetized. Let the fitness function be f(X i ), fitness function f(X i ) is smaller, the corresponding fitness value is better;

[0041] Then the current individual historical optimal position P of individual i in the tth generation is i (t) is determined by the following formula:

[0042]

[0043] Then the optimal position P experienced by all individuals in the entire population in the tth generation is g (t), that is, the global historical optimal position P g (t) is determined by the following formula:

[0044] P g (t)={P1(t), P2(t),...,P N (t)}|f(P g (t))=min{f(P1(t)), f(P2(t)),..., f(P N (t))} (2)

[0045] Then the search formula v for the flight speed of individual i in the t+1th generation is ij (t+1) and the search formula for the position of individual i x ij (t+1) can be described as:

[0046] v ij (t+1)=v ij (t)+c1×r 1j (t)*(p ij (t)-x ij (t))+c2×r 2j (t)*(p gj (t)-x ij (t))(3)

[0047] x ij (t+1)=x ij (t)+v ij (t+1) (4)

[0048] Among them, the subscript "j" represents the jth dimension of the individual; "i" represents individual i; "t" represents the tth generation; r1~U(0,1), r2~U(0,1) are two independent random functions; c1 and c2 are acceleration constants, usually between 0 and 2, c1 is the step length for adjusting the individual to fly to the optimal position, and c2 is the step length for adjusting the individual to fly to the global optimal position;

[0049] The search space of individual i is limited to [-x max , x max ], that is, the position x of individual i ij ∈[-x max , x max ], in order to reduce the possibility of individuals leaving the search space during the evolution process, v ij Usually it is set within a certain range, that is, v ij ∈[-v max , v max ]; then v max =k×x max , k is a coefficient, the value is 0.1≤k≤1.0, x max is the maximum position, v max is the maximum speed;

[0050] The data input of formula (1), formula (2), formula (3) and formula (4) adopts full numerical real number input, so that the whole calculation process adopts full numerical operation and the calculation output result is more intuitive.

[0051] See attached Figure 1 The specific steps of the demagnetization current optimization adjustment method are as follows:

[0052] Step 1: Initialize the group and individuals. The initialization process is as follows: ① Set the group size N, that is, the number of individuals in the group is N; ② Set the position x of individual i ij ∈[-x max , x max ], that is, for any i and j, in [-x max , x max ] follows uniform distribution to generate x ij ; ③ Set v of individual i ij ∈[-v max , v max ], that is, for any i, j, in [-v max , v max ] follows uniform distribution to generate vij ;

[0053] Step 2: According to the initialization process, the position and flight speed of the individual are initially set, and the initial position is used as the current individual historical optimal position, that is, P is set. i =X i ; Then compare the individual historical optimal position P of each individual i , find the initial global historical optimal position P g ;

[0054] Step 3: Search the flight speed and position of the individual according to formula (3) and formula (4), and calculate the fitness function f(X i )value;

[0055] Step 4: For each individual, set the current position X i The fitness function f(X i ) value and the current individual historical optimal position P i The fitness function f(P i ) values, if f(X i )<f(P i ), then the individual's current position X i As the current individual historical optimal position P i ; If f(X i )≥f(P i ), then the individual's current individual historical optimal position P i remain unchanged;

[0056] Step 5: For all individuals, the current individual historical optimal position P of each individual is i The fitness function f(P i ) values ​​are respectively related to the current global historical optimal position P g The fitness function f(P g ) values, if f(Pi)<f(P g ), then the individual's current individual historical optimal position P i As the current global historical optimal position P g ; If f(P i )≥f(P g ), then the current global historical optimal position P g remain unchanged;

[0057] Step 6: According to the current global historical optimal position P obtained in step 5 g , to determine whether the termination condition is reached. If the current global historical optimal position P gWhen the corresponding demagnetization current reaches the preset value, the adjustment of the demagnetization current is terminated, and the optimal adjustment of the demagnetization current is achieved; if the previous global historical optimal position P g If the corresponding demagnetization current does not reach the preset value, repeat steps 3 to 6 for iterative calculation until the current global historical optimal position P g When the corresponding demagnetization current reaches a preset value or reaches a preset maximum number of iterations, the adjustment of the demagnetization current is terminated, and the optimal adjustment of the demagnetization current is achieved.

[0058] See attached Figure 2 The implementation process of the distributed degaussing system degaussing current optimization adjustment method is as follows:

[0059] The first step is to set the calculation program parameters, including acceleration constants c1 and c2, maximum speed v max , group size N, individual dimension D, individual's maximum adjustment range and termination conditions;

[0060] The second step is to measure the original magnetic field of the ship: the demagnetization coil is not working, and the longitudinal passing characteristics of the vertical magnetic field of the ship at a certain depth under the port, keel and starboard side are measured in the four headings of magnetic east, south, west and north. Five quantities are calculated according to the formula. The five quantities are the vertical component of the longitudinal magnetization induction of the ship, the vertical component of the longitudinal magnetization fixed of the ship, the vertical component of the transverse magnetization induction of the ship, the vertical component of the transverse magnetization fixed of the ship and the vertical component of the vertical magnetization of the ship. The data of each quantity are arranged in the order of the stern to the bow of the port side of the ship, the stern to the bow of the keel and the stern to the bow of the starboard side. Finally, the data of the five quantities form five arrays;

[0061] The third step is to measure the winding efficiency of the demagnetization coil; load a current of 5A to each demagnetization coil, measure the magnetic field distribution caused by the demagnetization coil at each measuring point, and the magnetic field minus the original magnetic field of the ship in the same heading is the winding efficiency of the demagnetization coil; and the winding efficiency of the longitudinal demagnetization coil should be measured in the magnetic south or magnetic north heading, the winding efficiency of the transverse demagnetization coil should be measured in the magnetic east or magnetic west direction, and the winding efficiency of the vertical demagnetization coil can be measured in the magnetic east, south, west, and north headings; the winding efficiency of each demagnetization coil is stored as a column of arrays, and the number and position of array elements are the same as the elements of the original magnetic field array of the ship; the longitudinal demagnetization coil is used to compensate for the vertical component of the ship's longitudinal magnetization induction and the fixed vertical component of the ship's longitudinal magnetization, the transverse demagnetization coil is used to compensate for the vertical component of the ship's transverse magnetization induction and the fixed vertical component of the ship's transverse magnetization, and the vertical demagnetization coil is used to compensate for the vertical component of the ship's vertical magnetization.

[0062] The fourth step is to input the original magnetic field of the ship in the second step and the winding efficiency of the demagnetization coil in the third step as parameters into the program, and then start the program. The program will automatically perform optimization iterative calculations until the calculation results meet the termination conditions, and then output the optimal combination of demagnetization currents. The combination is an array, and each element in the array corresponds to the demagnetization current of a demagnetization coil. The demagnetization current value is set to the actual working current of the corresponding demagnetization coil, and the demagnetization system power supply is started. When all demagnetization coils are powered on at the same time, the magnetic field of the demagnetization coil will compensate for the ship's magnetic field, so that the peak error of the compensated ship's residual magnetic field is minimized.

[0063] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for optimizing and adjusting the demagnetization current of a distributed demagnetization system, wherein the demagnetization current of each demagnetization coil is regarded as an individual without mass and volume, and all individuals form a group; each individual has its own flight speed, position and fitness value determined by a fitness function, wherein the flight speed is the step length of the demagnetization current change, and the position is the current value of the demagnetization current changing with the step length; It is characterized in that The specific steps of the demagnetization current optimization adjustment method are as follows: Step 1: Initialize the position and flight speed of the individual, and use the initial position as the current individual historical optimal position. Then compare the individual historical optimal positions of each individual to find the global historical optimal position at the initial time. Step 2: Search the flight speed and position of the individual, and calculate the flight speed of each individual i at the current position X i The fitness function f(X i )value; Step 3: For each individual i, the current position X i The fitness function f(X i ) value and the current individual historical optimal position P i The fitness function f(P i ) values, if f(X i )<f(P i ), then the individual's current position X i As the current individual historical optimal position P i ; If f(X i )≥f(P i ), then the individual's current individual historical optimal position P i remain unchanged; Step 4: For all individuals, the current individual historical optimal position P of each individual i is i The fitness function f(P i ) values ​​are respectively related to the current global historical optimal position P g The fitness function f(P g ) values, if f(P i )<f(P g ), then the individual's current individual historical optimal position P i As the current global historical optimal position P g ; If f(P i )≥f(P g ), then the current global historical optimal position P g remain unchanged; Step 5: According to the current global historical optimal position P obtained in step 4 g , to determine whether the termination condition is reached. If the current global historical optimal position P g The corresponding demagnetization current reaches the preset value, then the adjustment of the demagnetization current ends; if the previous global historical optimal position P g If the corresponding demagnetization current does not reach the preset value, repeat steps 2 to 5 for iterative calculation until the current global historical optimal position P g When the corresponding demagnetization current reaches a preset value or reaches a preset maximum number of iterations, the adjustment of the demagnetization current is terminated.

2. A method for optimizing and adjusting degaussing current of a distributed degaussing system as claimed in claim 1, characterized in that: Assume that the number of individuals in the population is N; the dimension of each individual is D; the current position of individual i is X i =(x i1 , x i2 , ..., x iD ); the current flight speed of individual i is V i =(v i1 , v i2 , ..., v iD ); Individual i’s individual historical optimal position P i =(p i1 , p i2 , ..., p iD ); In step 3, the current individual historical optimal position P of individual i in the tth generation i (t) is determined by the following formula:

3. A method for optimizing and adjusting degaussing current of a distributed degaussing system as claimed in claim 2, characterized in that: In step 4, the current global historical optimal position P of the entire population in the tth generation g (t) is determined by the following formula: P g (t)={P1(t),P2(t),...,P N (t)}|f(P g (t))=min{f(P1(t)),f(P2(t)),...,f(P N (t))}(2)。 4. A method for optimizing and adjusting degaussing current of a distributed degaussing system according to any one of claims 1 to 3, characterized in that: Assume that the number of individuals in the population is N; the dimension of each individual is D; the current position of individual i is X i =(x i1 , x i2 , ..., x iD ); the current flight speed of individual i is V i =(v i1 , v i2 , ..., v iD ); Individual i’s individual historical optimal position P i =(p i1 , p i2 , ..., p iD ); In step 2, the search formula v for the flight speed of individual i in the t+1th generation is ij (t+1) and the search formula for the position of individual i x ij (t+1) can be described as: v ij (t+1)=v ij (t)+c1×r 1j (t)*(p ij (t)-x ij (t))+c2×r 2j (t)*(p gj (t)-x ij (t)) (3) x ij (t+1)=x ij (t)+v ij (t+1) (4) Wherein, the subscript "j" represents the jth dimension of the individual; r1~U(0,1), r2~U(0,1) are two independent random functions; c1 and c2 are acceleration constants, which take values ​​between 0 and 2.

5. A method for optimizing and adjusting degaussing current of a distributed degaussing system as claimed in claim 4, characterized in that: The position x of individual i ij ∈[-x max , x max ], flight speed v ij ∈[-v max , v max ]; then v max =k×x max , k is a coefficient, with a value of 0.1≤k≤1.0, where x max is the maximum position, v max is the maximum speed.

6. A method for optimizing and adjusting degaussing current of a distributed degaussing system as claimed in claim 2 or 3, characterized in that: The value of D is 1, 2, or 3.

7. A method for optimizing and adjusting degaussing current of a distributed degaussing system as claimed in claim 4, characterized in that: The value of D is 1, 2, or 3.

8. The method for optimizing and adjusting the degaussing current of a distributed degaussing system according to claim 1, characterized in that: The implementation process of the distributed degaussing system degaussing current optimization adjustment method is as follows: The first step is to set the calculation program parameters; The second step is to measure the original magnetic field of the ship: The third step is to measure the winding efficiency of the degaussing coil; The fourth step is to input the original magnetic field of the ship in the second step and the winding efficiency of the demagnetization coil in the third step as parameters into the program, and then start the program. The program will automatically perform optimization iterative calculations until the calculation results meet the termination conditions, and then output the optimal combination of demagnetization currents. The combination is an array, and each element in the array corresponds to the demagnetization current of a demagnetization coil. The demagnetization current value is set to the actual working current of the corresponding demagnetization coil, and the demagnetization system power supply is started. When all demagnetization coils are powered on at the same time, the magnetic field of the demagnetization coil will compensate for the ship's magnetic field, so that the peak error of the compensated ship's residual magnetic field is minimized.

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