CN115079995B

CN115079995B - Method and system for sequencing measured sample measuring points of neutron spectrometer

Info

Publication number: CN115079995B
Application number: CN202210859831.9A
Authority: CN
Inventors: 谢敬华; 钟掘; 秦金博; 周汩瑞
Original assignee: Central South University
Current assignee: Central South University
Priority date: 2022-07-22
Filing date: 2022-07-22
Publication date: 2022-11-11
Anticipated expiration: 2042-07-22
Also published as: CN115079995A

Abstract

The application discloses a method and a system for sequencing measured sample measuring points of a neutron spectrometer, wherein the method comprises the following steps: the coordinates of a measured point, a measured vector, the coordinates of a diffraction point and a scattering vector are represented in a base coordinate system; taking the minimum movement time of the sample stage as a target function; taking each measuring point sequencing scheme as a chromosome in a genetic algorithm; iteratively operating the chromosome according to the preset iteration times; calculating the corresponding fitness of each chromosome in each generation according to the fitness function until the fitness corresponding to the optimal individual in the obtained chromosome meets a preset condition; and the measuring point sequencing scheme corresponding to the optimal individual is used for measuring the measured sample. The method and the device solve the problem that the measured sample measuring points of the neutron spectrometer are sequenced manually in the prior art, so that the measuring point sequence planning can be automatically completed on a computer, and the measuring time can be shortened and the measuring efficiency can be improved by moving the sample stage according to the planned measuring point sequence.

Description

Method and system for sequencing measured sample measuring points of neutron spectrometer

Technical Field

The application relates to the field of measurement of residual stress of neutron scattering materials, in particular to a method and a system for sequencing measured points of a measured sample of a neutron spectrometer.

Background

The regulation and measurement of the internal stress of the material are one of factors influencing the level of the manufacturing industry, and the internal stress of the material has great influence on the manufacturing precision and the performance of the product. The method has the advantages of deeply researching the internal stress generation mechanism of the material, analyzing the internal stress distribution rule of the part, improving the internal stress measurement precision and having important significance for improving the development level of the high-precision manufacturing technology.

The neutron spectrometer is a device for detecting deep stress of various metal materials and engineering components, wherein a sample stage is one of important devices of the whole device. The neutron spectrometer sample stage is a device for installing a measured sample and moving a measuring point and a measuring direction on the measured sample to a neutron diffraction point and a scattering vector direction for stress measurement, and each moving pair of the sample stage needs to be combined to act in the process of stress measurement of the sample, so that the measured points are accurately positioned. The sample platform often can occupy too much experimental time at the in-process of fixing a position every measurement station, because neutron beam has the radiativity, the experimental time overlength can influence the experimenter healthy, simultaneously because nuclear reactor can consume a large amount of neutron beams for work for a longer time, causes the energy waste, therefore the time should be shortened as far as possible in the process of neutron spectrometer stress measurement, improves measurement of efficiency.

In order to improve the measurement efficiency, the movement time of the sample stage can be reduced as much as possible by reasonably planning the movement path of the sample stage so as to improve the measurement efficiency, namely, the measured points of the measured sample are reasonably sequenced. At present, before a spectrometer is used for measuring stress, experimenters can carry out full preparation, the sequence of measured points is reasonably arranged manually, and the movement of a sample table is controlled according to the sequence, so that the process usually consumes a great deal of time and energy of the experimenters, and the working efficiency is low; meanwhile, the shortest total moving time of the sample stage is difficult to realize by the sequence of the measured points planned manually.

Disclosure of Invention

The embodiment of the application provides a method and a system for sequencing measured sample measuring points of a neutron spectrometer, which are used for at least solving the problem that the measured sample measuring points of the neutron spectrometer depend on manual sequencing in the prior art.

According to one aspect of the application, a method for sequencing measured sample measuring points of a neutron spectrometer is provided, and comprises the following steps: the coordinates of a measured point, a measured vector, the coordinates of a diffraction point and a scattering vector are represented in a base coordinate system; taking the minimum motion time of the sample stage as an objective function, wherein the objective function is used for indicating the motion time of returning to the initial position after the sample stage traverses and moves to each measuring point from the initial position, and the motion time is calculated according to the coordinates of the measured point, the measured vector, the coordinates of the diffraction point and the scattering vector; taking each measuring point sequencing scheme as a chromosome in a genetic algorithm, wherein each chromosome comprises all measuring points in different sequences, an initial point and an end point, and the initial point and the end point are points corresponding to the initial position; performing iterative operation on chromosomes according to the preset iterative times, wherein each iterative operation is to perform selection operation, crossover operation and mutation operation on the previous generation of chromosomes to obtain the next generation of chromosomes; calculating the corresponding fitness of each chromosome in each generation according to a fitness function until the fitness corresponding to the optimal individual in the obtained chromosome meets a preset condition, wherein the fitness function is established according to the objective function; and the measuring point sequencing scheme corresponding to the optimal individual is used for measuring the measured sample.

Further, the objective function is:

；

wherein p is ₀ Denotes the initial position of the sample stage, R = (p) ₁ ,p ₂ ,…,p _N ) For a set of all measured points, N represents the number of measured points,

representing the sequencing scheme of the final measured points satisfying the objective function in R (a) ₁ ,a ₂ …,a _N ) Denotes a non-repeating number within the range of 1~N,

representing the point to be measured

When the position and the measured vector of (A) are located in the direction of the diffraction point and the scattering vector of (B)

The position of the diffraction point and the time required for the measured vector to move to the direction of the diffraction point and the scattering vector,

indicating the point to be measured when the sample stage is at the initial position

representing the point to be measured

And measuring the time required by the sample platform to return to the initial position after the measurement is finished.

Further, the fitness function is:

wherein, the fitness (i) is the fitness value of the ith individual in the population; t (i) is the measuring time corresponding to the ith individual in the population; minT is the minimum value of the corresponding measurement time of all individuals in the population; maxT is the maximum value of the corresponding measurement time of all individuals in the population; epsilon is a preset value to avoid the fitness function being invalid when maxT-minT =0.

Further, iteratively operating on the chromosome includes: each iteration operation is to perform selection operation, crossover operation and mutation operation on the previous generation of chromosomes to obtain the next generation of chromosomes.

Further, the selecting operation includes: the fitness value of each individual in the population of the current generation is arranged from large to small, wherein a ₁ 、a _n Respectively the maximum and minimum fitness value in the population, and the fitness a ₁ Multiplying by the reward factor omega ₁ (ii) a To fitness a _n Multiplying by a penalty factor omega ₂ (ii) a Wherein, ω is ₁ >1，0<ω ₂ <1。

Further, the interleaving operation comprises: generating a random number for a pair of chromosomes, if the random number is greater than or equal to the crossover probability P _c And performing crossover operation, otherwise, reselecting a pair of chromosomes from the rest chromosomes to continue generating a random number, and judging whether crossover operation can be performed.

Further, the mutation operation comprises: generating a random number for each chromosome if the random number is greater than or equal to the mutation probability P _m Any two locations are swapped for the coordinate number.

Further, the predetermined condition satisfied includes: acquiring a preset maximum iteration number MAX, counting an iteration number Gen in the process of iterative evolution, and if the iteration number Gen is greater than the maximum iteration number MAX, terminating iteration; or, setting the iteration number of which the optimal fitness keeps unchanged as F, acquiring the maximum preset iteration number of which the fitness keeps unchanged as MAX _ F, counting F in the iterative evolution process, and if F is greater than MAX _ F, terminating iteration.

According to another aspect of the application, a sequencing system for measured sample measuring points of a neutron spectrometer is further provided, and comprises: the representing module is used for representing the coordinates of the measured point, the measured vector, the coordinates of the diffraction point and the scattering vector in the base coordinate system; the processing module is used for taking the minimum movement time of the sample stage as an objective function, wherein the objective function is used for indicating the movement time of the sample stage returning to the initial position after traversing and moving from the initial position to each measuring point, and the movement time is calculated according to the coordinates of the measured point, the measured vector, the coordinates of the diffraction point and the scattering vector; the iteration module is used for taking each measuring point sequencing scheme as a chromosome in a genetic algorithm, wherein each chromosome comprises all measuring points in different sequences, an initial point and an end point, and the initial point and the end point are points corresponding to the initial position; performing iterative operation on chromosomes according to the preset iterative times, wherein each iterative operation is to perform selection operation, crossover operation and mutation operation on the previous generation of chromosomes to obtain the next generation of chromosomes; the calculation module is used for calculating the corresponding fitness of each chromosome in each generation according to a fitness function until the fitness corresponding to the optimal individual in the obtained chromosome meets a preset condition, wherein the fitness function is established according to the target function; and the measuring point sequencing scheme corresponding to the optimal individual is used for measuring the measured sample.

According to another aspect of the present application, there is also provided a memory for storing software for performing the above-described method.

According to another aspect of the application, there is also provided a processor for running software for performing the above method.

In the embodiment of the application, the coordinates of a measured point, a measured vector, the coordinates of a diffraction point and a scattering vector are expressed in a base coordinate system; taking the minimum motion time of the sample stage as an objective function, wherein the objective function is used for indicating the motion time of the sample stage returning to the initial position after traversing and moving from the initial position to each measuring point, and the motion time is calculated according to the coordinates of the measured point, the measured vector, the coordinates of the diffraction point and the scattering vector; taking each measuring point sequencing scheme as a chromosome in a genetic algorithm, wherein each chromosome comprises all measuring points in different sequences, an initial point and an end point, and the initial point and the end point are points corresponding to the initial position; performing iterative operation on chromosomes according to the preset iterative times, wherein each iterative operation is to perform selection operation, crossover operation and mutation operation on the previous generation of chromosomes to obtain the next generation of chromosomes; calculating the corresponding fitness of each chromosome in each generation according to a fitness function until the fitness corresponding to the optimal individual in the obtained chromosome meets a preset condition, wherein the fitness function is established according to the objective function; and the measuring point sequencing scheme corresponding to the optimal individual is used for measuring the measured sample. The method and the device solve the problem that the measured sample measuring points of the neutron spectrometer are sequenced manually in the prior art, so that the measuring point sequence planning can be automatically completed on a computer, and the measuring time can be shortened and the measuring efficiency can be improved by moving the sample stage according to the planned measuring point sequence.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, are included to provide a further understanding of the application, and the description of the exemplary embodiments of the application are intended to be illustrative of the application and are not intended to limit the application. In the drawings:

FIG. 1 is a simplified structural diagram of a sample stage of a neutron spectrometer according to an embodiment of the present application;

FIG. 2 is a schematic diagram of neutron diffraction measurement of residual stress according to an embodiment of the present application;

FIG. 3 is a diagram of a roulette selection principle according to an embodiment of the present application;

FIG. 4 is a direct crossover schematic according to an embodiment of the present application;

FIG. 5 is a diagram of an improved crossover operation according to an embodiment of the present application;

FIG. 6 is a schematic diagram of variant operation according to an embodiment of the present application;

FIG. 7 is an overall flowchart of the intelligent sequencing of the measured sample measuring points of the neutron spectrometer according to the embodiment of the application;

FIG. 8 is a simplified diagram of the joint structure of the sample stage and a schematic diagram of the coordinate system of each stage joint and the table top according to the embodiment of the present application;

FIG. 9 is a schematic diagram of a coordinate system of a measured sample and a mounting position of the coordinate system on a table according to an embodiment of the application;

FIG. 10 is a diagram of a relationship between a diffraction coordinate system and a base coordinate system (top view direction) according to an embodiment of the present application;

FIG. 11 is a schematic view of a station sequence according to an embodiment of the present application;

FIG. 12 is a graph of optimal sequencing convergence according to an embodiment of the present application;

FIG. 13 is a schematic diagram of a method for intelligently sequencing measured sample points of a neutron spectrometer according to an embodiment of the application.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.

It should be noted that the steps illustrated in the flowcharts of the figures may be performed in a computer system such as a set of computer-executable instructions and that, although a logical order is illustrated in the flowcharts, in some cases, the steps illustrated or described may be performed in an order different than presented herein.

The structure and the operation principle of the sample stage in the following examples will be explained first. Fig. 1 is a schematic structural diagram of a sample stage of a neutron spectrometer according to an embodiment of the present application, and as shown in fig. 1, the schematic structural diagram of the sample stage of the neutron spectrometer is shown. The whole sample stage of the neutron spectrometer has 4 degrees of freedom, wherein 1 is a rotary joint of the sample stage rotating around a Z axis, 2 is a moving joint of the sample stage in the Z axis direction, 3 is a moving joint of the sample stage in the Y axis direction, 4 is a moving joint of the sample stage in the X axis direction, and 5 is a table top of the sample stage and used for mounting a sample 6 to be measured. When the residual stress of the measured sample is measured, the measured sample is installed on a table board, the measured sample is driven to move through joint actions of the sample table, the measured point position on the measured sample is aligned with a diffraction point, the measured vector is aligned with a scattering vector, and therefore neutron residual stress measurement is performed, the stress principle of neutron diffraction measurement is shown in fig. 2, a single-energy neutron incident beam irradiates the diffraction point of the measured sample through an incident slit to generate a transmitted beam and an emergent beam, the emergent beam reaches a two-dimensional position sensitive detector (PSD for short) through a receiving slit, and the scattering vector shown in fig. 2 can be obtained.

Based on the neutron spectrometer shown in fig. 1 and fig. 2, in this embodiment, a method for sequencing measured points of a measured sample of the neutron spectrometer is provided, where the method includes the following steps:

step S102, representing coordinates of a measured point, a measured vector, coordinates of a diffraction point and a scattering vector in a base coordinate system;

step S104, taking the minimum motion time of the sample stage as an objective function, wherein the objective function is used for indicating the motion time of returning to the initial position after the sample stage traverses and moves to each measuring point from the initial position, and the motion time is calculated according to the coordinates of the measured point, the measured vector, the coordinates of the diffraction point and the scattering vector;

step S106, taking each measuring point sequencing scheme as a chromosome in a genetic algorithm, wherein each chromosome comprises all measuring points in different sequences, an initial point and an end point, and the initial point and the end point are points corresponding to the initial position;

step S108, iteratively operating chromosomes according to preset iteration times, wherein each iterative operation is to perform selection operation, crossover operation and mutation operation on the previous generation of chromosomes to obtain the next generation of chromosomes;

step S110, calculating corresponding fitness for each chromosome in each generation according to a fitness function until the fitness corresponding to the optimal individual in the obtained chromosome meets a preset condition, wherein the fitness function is established according to the objective function; and the measuring point sequencing scheme corresponding to the optimal individual is used for measuring the measured sample.

Through the steps, the problems existing in the prior art that the measured sample measuring points of the neutron spectrometer are sequenced manually are solved, so that the measuring point sequence planning can be automatically completed on a computer, and the measuring time can be shortened and the measuring efficiency can be improved by moving the sample table according to the planned measuring point sequence.

The present embodiment will be described below with reference to the accompanying drawings. The embodiment relates to the field of neutron scattering-material residual stress measurement, in particular to a method for intelligently sequencing measured points of a measured sample of a neutron spectrometer. Fig. 13 is a schematic diagram of a method for intelligently sequencing measured sample points of a neutron spectrometer according to an embodiment of the application, and as shown in fig. 13, the method mainly includes three steps: (1) modeling the kinematics of a sample stage of a neutron spectrometer: establishing a coordinate system for each joint of the sample table; the coordinates of the measured points and the measured vectors are represented in the base coordinate system; diffraction point coordinates and a scattering vector are shown in the base coordinate system. (2) establishing an optimization objective function: and establishing an objective function by taking the minimum motion time of the sample stage as an optimization target. (3) improving a genetic algorithm: the coding, selection, crossing and mutation operations of the basic genetic algorithm are improved in combination with reality; designing a fitness function; and the whole process of the intelligent sequencing of the measured sample measuring points of the neutron spectrometer is provided by combining with an improved genetic algorithm. The above steps are explained below.

Kinematic modeling of sample stage

(1) Method for representing coordinates and vectors of measured points in base coordinate system

In order to show the coordinates and the measured vectors of the measured points in the base coordinate system, firstly establishing a coordinate system of each joint for the structure of the sample platform according to an improved D-H method, which specifically comprises the following steps: base coordinate system X ₀ Y ₀ Z ₀ Z-axis rotary joint coordinate system X ₁ Y ₁ Z ₁ Z-axis moving joint coordinate system X ₂ Y ₂ Z ₂ Y-axis moving joint coordinate system X ₃ Y ₃ Z ₃ X-axis moving joint coordinate system X ₄ Y ₄ Z ₄ Table top coordinate system X ₅ Y ₅ Z ₅ (ii) a And determining an improved D-H parameter table of each joint of the sample table according to the established coordinate system.

According to a homogeneous transformation matrix between the i-1 and i coordinate systems of adjacent joints of the sample table:

in the formula of alpha _i-1 Represents around X _i-1 Axis from Z _i-1 The shaft being rotated to Z _i The angle of the shaft, i.e. the link torsion angle; a is _i-1 Represents along X _i-1 Axis from Z _i-1 Movement of the shaft to Z _i Distance of the shaft, i.e. link length; d _i Represents along Z _i Axis from X _i-1 Movement of the shaftTo X _i Distance of axes, i.e. link distance, theta _i Represents around Z _i Axis from X _i-1 The shaft being rotated to X _i The angle of the shaft, i.e. the link angle.

Substituting the improved D-H parameters of each level of joint of the sample table into the formula, obtaining a transformation matrix among four joint coordinate systems:

、

、

、

。

simultaneously according to the table coordinate system X ₅ Y ₅ Z ₅ And X-axis moving joint coordinate system X ₄ Y ₄ Z ₄ The transformation relation between the two coordinate systems can be obtained

。

Let the coordinate system of the measured sample be X _j Y _j Z _j Coordinate system X ₅ Y ₅ Z ₅ And X _j Y _j Z _j A transformation matrix of

，

The mounting position of the tested sample on the table top is specifically determined.

The position of a measured point in a measured sample coordinate system is (x) _c ,y _c ,z _c ) The measured vector is expressed as (x) under the coordinate system of the measured sample _v ,y _v 0), the homogeneous coordinate C = (x) of the position coordinate of the measured point in the measured sample coordinate system _c ,y _c ,z _c ,1) ^T And the homogeneous coordinate V = (x) of the measured vector in the measured sample coordinate system _v ,y _v ,0,0) ^T 。

According to the transformation matrix among the plurality of coordinate systems:

、

、

、

、

、

and homogeneous coordinates C and V of the position coordinates of the measured point and the measured vector in the coordinate system of the measured sample can obtain a representation method of the coordinates of the measured point and the measured vector in the base coordinate system, which comprises the following steps:

homogeneous coordinate of measured point coordinate under base coordinate

Comprises the following steps:

the coordinates of the measured point are expressed as (X) in the base coordinate system _c ,Y _c ,Z _c )。

Homogeneous coordinate of measured vector under base coordinate

The measured vector is represented as (X) in the base coordinate system _v ,Y _v ,Z _v )。

(2) Method for representing diffraction point coordinates and scattering vectors in basic coordinate system

In order to represent the diffraction point coordinates and the scattering vector in the base coordinate system, a diffraction coordinate system is first established. The establishment method comprises the following steps: with diffraction point as origin and Z in vertical direction _m Axis, incident beam direction X _m Axis, Y determined by right-hand rule _m Axis, can establish a diffraction coordinate system X _m Y _m Z _m 。

According to a base coordinate system X ₀ Y ₀ Z ₀ And a diffraction coordinate system X _m Y _m Z _m The transformation relation between the two can obtain a transformation matrix between the two

。

Let the diffraction point coordinate be (0,0,0) in the diffraction coordinate system, and the scattering vector be (x) in the diffraction coordinate system _q ,y _q 0), then the homogeneous coordinate M = (0,0,0,1) of the diffraction point coordinate in the diffraction coordinate system ^T Homogeneous coordinate Q = (x) of scattering vector in diffraction coordinate system _q ,y _q ,0,0) ^T 。

According to the transformation matrix

And homogeneous coordinates M and Q of the diffraction point coordinates and the scattering vectors in the diffraction coordinate system can obtain a representation method of the diffraction point coordinates and the scattering vectors in the basic coordinate system, which comprises the following steps:

homogeneous coordinate of diffraction point coordinate under base coordinate

：

The diffraction point coordinates are expressed as (X) in the base coordinate system _m ,Y _m ,Z _m )。

Homogeneous coordinate of Q scattering vector under base coordinate

：

The scattering vector is then expressed as (X) in the base coordinate system _q ,Y _q ,Z _q )。

Establishing an objective function

During stress measurement, the position coordinates (X) of the measured point _c ,Y _c ,Z _c ) Co-diffraction point coordinate (X) _m ,Y _m ,Z _m ) Alignment, vector (X) to be measured _v ,Y _v ,Z _v ) Common scattering vector (X) _q ,Y _q ,Z _q ) And aligning, wherein the four joint variables of the sample table are a set of fixed values, when the next measured point is measured, the four joint variables of the sample table are changed, and the absolute value of the change of the four joint variables in the process is the translation or rotation amount of the corresponding joint.

In order to realize the intelligent sequencing of the measured sample measuring points in the neutron spectrometer and improve the measuring efficiency, the invention takes the minimum movement time of the sample stage as an objective function and provides the following objective functions:

is represented by R inFinal measured point ordering scheme satisfying target function (a) ₁ ,a _2, …,a _N ) Denotes a non-repeating number within the range 1~N,

representing the measured point

indicating the point to be measured when the sample stage is in the initial position

representing the measured point

、

、

The specific calculation formula of (2) is as follows:

wherein

、

、

Respectively represent the measured points

When the position and the measured vector of (2) are located in the directions of the diffraction point and the scattering vector

The position and the measured vector of the sample stage are moved to the directions of the diffraction point and the scattering vector, and the X-axis translation amount, the Y-axis translation amount, the Z-axis translation amount and the Z-axis rotation angle of the sample stage are obtained;

、

、

、

respectively shows the measured points when the sample stage is at the initial position

The position and the measured vector of (A) are moved to the diffraction point and the direction of the scattering vectorX-axis translation amount, Y-axis translation amount, Z-axis translation amount and Z-axis rotation angle of the sample stage;

respectively represent the measured points

After the measurement is finished, when the sample platform returns to the initial position, the X-axis translation amount, the Y-axis translation amount, the Z-axis translation amount and the Z-axis rotation angle of the sample platform are measured; v. of _x 、v _y 、v _z Respectively represent the X-axis, Y-axis and Z-axis moving speeds of the sample platform, and omega represents the angular speed of the sample platform rotating around the Z-axis.

Improved genetic algorithm

The genetic algorithm is a method for searching an optimal solution by simulating a natural evolution process, and has the main advantages that a structural object is directly operated, and a target function value is used as searching information, so that complex operations such as derivation and the like are avoided; by adopting a probabilistic optimization method, the optimized search space can be automatically acquired and guided without a determined rule, and the search direction is adaptively adjusted; the system has expandability and is convenient to be mixed with other technologies for use.

The algorithm firstly encodes potential solutions of problems, each individual represents a solution of a genetic algorithm, then processes of selection, crossing, variation and the like of chromosome genes in biological evolution are simulated, new filial generations are continuously generated, and the fitness function is adopted to simulate the advantages and disadvantages of the nature to judge the advantages and disadvantages of the new solutions until the optimal solutions are generated.

In the embodiment, the practical problems in the neutron spectrometer test process are combined, the genetic algorithm is adaptively improved, and the intelligent sequencing method for the measured sample measuring points of the neutron spectrometer based on the genetic algorithm is provided. In the steps, a neutron spectrometer sample table is subjected to kinematic modeling, an optimized objective function for intelligently sequencing measured points of a measured sample of the neutron spectrometer is established, and then the objective function needs to be solved.

The neutron spectrometer mainly has the following characteristics when measuring the stress of a measuring point of a measured workpiece:

(1) The sample table is in the original position when the measurement is started, and the sample table needs to return to the original position after the measurement is finished;

(2) In the stress measurement process, any measuring point on a measured sample is measured once, namely point positions in a measuring path cannot be repeated;

(3) The measured workpiece is a three-dimensional object, and the measuring point positions are widely distributed in the three-dimensional space of the measured workpiece.

The method is characterized in that partial key steps of a genetic algorithm are introduced as follows by combining the characteristics of a neutron spectrometer when measuring the stress of a measuring point of a measured workpiece:

(1) And (5) encoding. The measuring point sequence of the measured sample of the neutron spectrometer is used as a chromosome in a genetic algorithm, and the coding mode is very suitable for the problem of path optimization of measurement. In the chromosome coding process, the initial coding point position and the end coding point position are both assigned to be 0, which means that the position of the sample stage needs to return to the initial point before the measurement starts and after the measurement ends, and except that the head and the tail two chromosome coding point positions are 0, other coding point positions adopt the measuring point numbers to carry out non-repeated coding, so the chromosome length N = the measuring point number +2.

(2) And (6) selecting operation. Selecting operation using the improved roulette strategy: firstly, the fitness value of each individual in the population of the current generation is arranged from large to small, wherein a ₁ 、a _n Respectively the maximum and minimum fitness value in the population, and the fitness a ₁ Multiplying by the reward factor omega ₁ (ω ₁ >1) So that the corresponding individuals can be better reserved in the next generation population; degree of adaptation a _n Multiplying by a penalty factor omega ₂ (0<ω ₂ <1) So that the corresponding individuals are easier to be eliminated, and the convergence of population iteration is improved. See formula:

an improved roulette selection scheme is shown in figure 3.

(3) And (4) performing a crossover operation. Generating a random number for a pair of chromosomes, if the random number is greater than or equal to the crossover probability P _c And performing the following crossover operation, otherwise, reselecting a pair of chromosomes from the rest chromosomes to continuously generate a random number, and judging whether the crossover operation can be performed. As shown in fig. 4, in the chromosome crossing process, both the crossing start point and the crossing length are randomly generated to improve the randomness of the population and avoid the algorithm from falling into local convergence. If the direct crossing is carried out according to the conventional genetic algorithm crossing principle, repeated coding point positions appear on a chromosome after the crossing is finished, the specific expression of the repeated coding point positions is that a certain measuring point of a workpiece is repeatedly measured, while certain measuring points are not measured, and the chromosome of the coding mode does not conform to the process of measuring stress of a neutron spectrometer sample stage.

Therefore, it is necessary to improve the above-mentioned crossing operation to avoid the repeated point locations on the chromosome, and the specific implementation principle is shown in fig. 5, in which the crossing length is exemplified by three point locations. And after determining the starting point position and the crossing length of the crossing, sequentially carrying out crossing operation according to the sequence of the point positions. Firstly, the first point location is crossed, the other point locations are not changed, and corresponding numbers on non-crossed positions are also exchanged in the crossing process, so that repeated numbers do not appear on a crossed chromosome; and by analogy, until the point position in the crossing length is crossed completely, repeated coding cannot occur on the whole chromosome at the moment, and the actual requirement is met.

(4) And (5) performing mutation operation. Generating a random number for each chromosome if the random number is greater than or equal to the mutation probability P _m Any two positions are taken to exchange the coordinate numbers as shown in fig. 6. Thus can ensureNo repeated coding occurs on the chromosome after mutation.

(5) A fitness function. At present, the optimization problem with the minimum time as the optimization target usually selects the reciprocal of the time used by an individual as the fitness value of the individual, but the fitness value obtained in this way is not proportional to the time, which may cause instability in the solution process. For the embodiment of the present invention, a fitness function is designed as shown in the following formula:

wherein, the fitness (i) is the fitness value of the ith individual in the population; t (i) is the measurement time corresponding to the ith individual in the population; minT is the minimum value of the corresponding measurement time of all individuals in the population; maxT is the maximum value of the corresponding measurement time of all individuals in the population; epsilon is a small value to avoid the fitness function being invalid when maxT-minT =0.

(6) And (5) an iteration termination condition. The genetic algorithm needs to specify an iteration termination condition in the iterative evolution process, and the currently commonly used iteration termination condition is as follows: presetting a maximum iteration number MAX in advance, counting an iteration number Gen in the iterative evolution process of the genetic algorithm, and if the iteration number Gen is greater than the maximum iteration number MAX, terminating the iteration; when the genetic algorithm reaches the optimal solution or falls into the local optimal solution in advance in the iterative evolution process, the iterative evolution can be continuously carried out under the limitation of the iterative termination condition, and the calculation efficiency is influenced.

In view of the above-mentioned shortcomings of the iteration termination condition, the embodiment of the present invention improves on the basis of the original iteration termination condition. And setting the iteration frequency of the optimal fitness keeping unchanged as F, and presetting the maximum iteration frequency of the fitness keeping unchanged as MAX _ F. The iteration termination condition provided by the invention is as follows: and F is counted in the iterative evolution process of the genetic algorithm, and if the F is greater than MAX _ F, the iteration is terminated.

In summary, the iteration termination condition of the embodiment of the present invention is: the genetic algorithm can terminate the iteration when the iterative evolution process meets any condition of Gen > MAX and F > MAX _ F.

In view of the above improvement on the genetic algorithm, the overall flowchart of the intelligent sequencing of the measured sample measuring points of the neutron spectrometer provided by this embodiment is shown in fig. 7. For the flowchart, the specific steps of the proposed scheme of the present embodiment are introduced as follows:

step 1, performing kinematic modeling on a sample stage, and constructing an objective function and a fitness function.

And 2, initializing the population. Initializing the parameter settings of the genetic algorithm: population number N, chromosome length M, maximum iteration number MAX _ F with constant optimal fitness, and cross probability P _c Probability of variation P _m (ii) a Importing the position and direction information of a measured point of a workpiece; the chromosomes are encoded and the original population is randomly generated.

And 3, calculating the fitness value of each chromosome in the population.

And 4, updating the iteration times of which the optimal fitness keeps unchanged.

And 5, carrying out selection operation.

And 6, performing cross operation.

And 7, performing mutation operation.

And 8, updating the iteration times.

And 9, judging whether the termination condition is met. If yes, outputting a final measuring point sequence.

The following description is made with reference to an example.

Sample stage structure and working principle

The neutron spectrometer sample platform in the embodiment can bear a large workpiece, can translate in three directions of a X, Y, Z shaft and rotate around a Z-axis direction, and has 4 degrees of freedom in movement. X, Y axial direction translation range is [ -250mm,250mm ], and translation precision is less than 30 μm; the translation range in the Z-axis direction is [0,550mm ], and the precision is 30 mu m; the rotation range is more than 360 degrees around the Z-axis direction, and the rotation precision is less than 0.05 degree; the sample stage can be used for bearing samples and sample environments such as high and low temperature, magnetic field and the like, and adjusting the samples to perform accurate angle control such as translation, rotation and the like. Wherein, the incident height of the neutron beam is 1400mm from the ground.

Kinematic modeling of sample stage

As shown in fig. 8, in order to show the coordinates of the measured point and the measured vector in the base coordinate system, the structure of the sample stage is first simplified, the coordinate systems of the joints are established according to the improved D-H method, and the coordinate system of the table top is established. Wherein X ₀ Y ₀ Z ₀ Is a base coordinate system fixed on the ground, Z ₀ The axis coincides with the central axis of the sample table; x ₁ Y ₁ Z ₁ Is a Z-axis rotary joint coordinate system, Z ₁ The axis coincides with the central axis of the sample table; x ₂ Y ₂ Z ₂ Is a Z-axis moving joint coordinate system, Z ₂ The axis coincides with the central axis of the sample table; x ₃ Y ₃ Z ₃ Is a Y-axis moving joint coordinate system, Z ₃ The axis coincides with the central axis of the ball screw moving along the Y axis; x ₄ Y ₄ Z ₄ Is the X-axis moving joint coordinate system, Z ₄ The axis coincides with the central axis of the ball screw moving along the Z axis; x ₅ Y ₅ Z ₅ Is a table top coordinate system, and the origin of the coordinate system is fixedly connected with the center of the table top.

The table of the modified D-H parameters for each joint of the sample stage is shown in Table 1.

TABLE 1 improved D-H PARAMETERS OF JOINTS OF SAMPLE TABLE

Wherein theta is ₁ The Z-axis rotation angle of the sample stage is represented, a positive value represents reverse rotation, and a negative value represents forward rotation; d ₂ Represents X ₂ Y ₂ The value of the distance between the coordinate plane and the ground changes along with the movement of the Z axis of the sample table, wherein the increase represents the upward movement, and the decrease represents the downward movement; d is a radical of ₃ The Y-axis movement distance of the sample stage is represented, positive values represent movement to the right direction, and negative values represent movement to the left direction; d ₄ The X-axis moving distance of the sample stage is represented, positive values represent forward movement, and negative values represent backward movement; a is ₃ Represents the center distance of the X-axis and Y-axis ball screws of the sample stage, in this example, a ₃ =150mm。

Each joint variable θ in the present embodiment ₁ 、d ₂ 、d ₃ 、d ₄ The ranges of (A) are shown in Table 2.

TABLE 2 Joint variable Range

in the formula of alpha _i-1 Represents around X _i-1 Axis from Z _i-1 The shaft being rotated to Z _i The angle of the shaft, i.e. the link torsion angle; a is _i-1 Represents along X _i-1 Axis from Z _i-1 Movement of the shaft to Z _i Distance of the shaft, i.e. link length; d _i Represents along Z _i Axis from X _i-1 The shaft being moved to X _i Distance of axes, i.e. link distance, theta _i Represents around Z _i Axis from X _i-1 The shaft being rotated to X _i The angle of the shaft, i.e. the link angle.

The improved D-H parameters of each level of joint coordinate system of the sample stage are substituted into the formula to obtain a transformation matrix between each level of joint coordinate system

、

、

、

As shown in the following formula:

table coordinate system X shown in fig. 8 ₅ Y ₅ Z ₅ Moving the joint coordinate system X relative to the X-axis ₄ Y ₄ Z ₄ The change relationship of (2) is as follows: coordinate system X ₄ Y ₄ Z ₄ First winding Y ₄ The axes rotate 90 degrees counterclockwise and then move (0, t) to the table coordinate system X along X, Y, Z of the coordinate system after rotation respectively ₅ Y ₅ Z ₅ And t represents the distance between the center of the X-axis ball screw of the sample table and the table top, and t =150mm in the embodiment. Then coordinate system X ₄ Y ₄ Z ₄ And X ₅ Y ₅ Z ₅ Transformation matrix between

Comprises the following steps:

，

The mounting position of the tested sample on the table top is specifically determined. The coordinate system of the sample to be measured and the mounting position on the table-board in this embodiment are shown in fig. 9.

Wherein the coordinate of the origin of the coordinate system of the sample to be measured on the table coordinate system is (40-75,0), and the coordinate system X of the sample to be measured _j Y _j Z _j Is in relation to the table coordinate system X ₅ Y ₅ Z ₅ The transformation relationship is as follows: rotated 90 about the Z5 axis. Then

Comprises the following steps:

the position of a measured point in a measured sample coordinate system is (x) _c ,y _c ,z _c ) The measured vector is expressed as (x) in the coordinate system of the measured sample _v ,y _v 0), homogeneous coordinate C = (x) of the position coordinate of the measured point in the coordinate system of the measured sample _c ,y _c ,z _c ,1) ^T And the homogeneous coordinate V = (x) of the measured vector in the measured sample coordinate system _v ,y _v ,0,0) ^T 。

In this embodiment, there are 16 sets of measured point information, each set of measured information includes the measured point position and the measured vector in the measured sample coordinate system, and the specific measured point information is shown in table 3.

TABLE 3 16 sets of measured point information

、

、

、

、

、

homogeneous coordinate of measured point coordinate under base coordinate

Comprises the following steps:

the coordinates of the measured point are expressed as (X) in the base coordinate system _c, Y _c ,Z _c )。

Homogeneous coordinate of measured vector under base coordinate

Comprises the following steps:

Example X _c ，Y _c ，Z _c ，X _v ，Y _v ，Z _v Is a parameter (theta) ₁ ,d ₂ ,d ₃ ,d ₄ ,x _c ,y _c ,z _c ,x _v ,y _v ) As a function of (c).

Fig. 10 is a diagram showing a relationship between a diffraction coordinate system and a base coordinate system in a top view direction. With diffraction point as origin and Z in vertical direction _m Axis, incident beam direction X _m Axis, Y determined by right-hand rule _m Axis, can establish a diffraction coordinate system X _m Y _m Z _m 。

Let the coordinates of the origin of the diffraction coordinate system in the base coordinate system be (0 _m ），X ₀ The shaft rotates to X _m The axial angle is theta, z in the present example _m =1400mm, θ = -135 °. Then coordinate system X ₀ Y ₀ Z ₀ And X _m Y _m Z _m Transformation matrix between

Comprises the following steps:

let the diffraction point coordinate be (0,0,0) in the diffraction coordinate system, and the scattering vector be (x) in the diffraction coordinate system _q ,y _q 0), the scattering vector in this embodiment is expressed as in the diffraction coordinate system

. Then the diffraction point coordinate is in the homogeneous coordinate M = (0,0,0,1) of the diffraction coordinate system ^T Homogeneous coordinate of scattering vector in diffraction coordinate system

。

According to the transformation matrix

homogeneous coordinate of diffraction point coordinate under base coordinate

:

Homogeneous coordinate of Q scattering vector under base coordinate

:

The scattering vector is then expressed as (X) in the base coordinate system _q ,Y _q ,Z _q ). Example X _q ,Y _q ,Z _q Is a constant value.

Establishing an objective function

During stress measurement, the position coordinate (X) of the measured point is measured _c ,Y _c ,Z _c ) Co-diffraction point coordinates (X) _m ,Y _m ,Z _m ) Alignment, the vector (X) to be measured _v ,Y _v ,Z _v ) Common scattering vector (X) _q ,Y _q ,Z _q ) And aligning, wherein the four joint variables of the sample table are a set of fixed values, when the next measured point is measured, the four joint variables of the sample table are changed, and the absolute value of the change of the four joint variables in the process is the translation or rotation amount of the corresponding joint.

In the embodiment of the invention, 16 measuring points are provided, in order to realize the intelligent sequencing of the measured sample measuring points in the neutron spectrometer and improve the measuring efficiency, the minimum movement time of the sample stage is taken as an objective function, and the following objective functions are provided:

wherein p is ₀ Denotes the initial position of the sample stage, R = (p) ₁ ,p ₂ ,…,p ₁₆ ) Is a set of 16 measured points,

representing the sequencing scheme of the final measured points satisfying the objective function in R (a) ₁ ,a ₂ …,a ₁₆ ) The numerical values are not repeated within the range of 1 to 16,

representing the measured point

representing the measured point

Suppose v _x 、v _y 、v _z Respectively showing the X-axis, Y-axis and Z-axis moving speeds of the sample stage, and omega showing the angular speed of the sample stage rotating around the Z-axis, in this embodiment, the sample stage v _x =20mm/s,v _y =20mm/s,v _z =10mm/s, and the angular velocity ω =6 °/s of the rotation of the sample stage about the Z axis.

Then

、

、

The specific calculation formula of (2) is as follows:

wherein

、

、

、

Respectively represent the measured points

、

、

、

The position and the measured vector of the sample stage are moved to the direction of the diffraction point and the scattering vector, and the X-axis translation amount, the Y-axis translation amount, the Z-axis translation amount and the Z-axis rotation angle of the sample stage are obtained;

、

、

、

respectively represent the measured points

And after the measurement is finished, when the sample table returns to the initial position, the X-axis translation amount, the Y-axis translation amount, the Z-axis translation amount and the Z-axis rotation angle of the sample table are measured.

Improved genetic algorithm

In the steps, a neutron spectrometer sample table is subjected to kinematic modeling, an optimized objective function for intelligently sequencing measured points of a measured sample of the neutron spectrometer is established, and then the objective function needs to be solved.

The optional embodiment combines some advantages and disadvantages of the genetic algorithm and the practical problem of intelligent sequencing of the measured sample measuring points of the neutron spectrometer to improve the genetic algorithm so as to achieve the aim of the invention.

The method introduces part of key steps of a genetic algorithm by combining the characteristics of a neutron spectrometer when measuring the stress of a measuring point of a measured workpiece:

(1) And (5) encoding. The measuring point sequence of the measured sample of the neutron spectrometer is used as a chromosome in a genetic algorithm, and the coding mode is very suitable for the problem of path optimization of measurement. In the process of coding the chromosome, the initial coding point position and the end coding point position are both assigned to be "0", which indicates that the position of the sample stage needs to return to the initial point before the start of measurement and after the end of measurement, and except for the two chromosome coding point positions at the head and the tail which are "0", other coding point positions adopt the number of the measuring points for non-repeated coding, so that the length of the chromosome N = the number of the measuring points +2, and the length of the chromosome N =18 in the optional embodiment.

(2) And (6) selecting operation. The selection is performed using a modified roulette strategy by first ranking the fitness value of each individual in the cohort of the current generation in descending order, where a ₁ 、a _n Respectively the maximum and minimum fitness value in the population, and the fitness a ₁ Multiplying by the reward factor omega ₁ (ω ₁ >1) So that the corresponding individuals can be better reserved in the next generation population; to fitness a _n Multiplying by a penalty factor omega ₂ (0<ω ₂ <1) So that the corresponding individuals are easier to be eliminated and the convergence of population iteration is improved. See formula:

reward factor omega in this alternative embodiment ₁ =1.2, penalty factor ω ₂ =0.8。

(3) And (4) performing a crossover operation. Generating a random number for a pair of chromosomes, if the random number is greater than or equal to the crossover probability P _c Performing the following crossover operation, otherwise, reselecting a pair of chromosomes from the rest chromosomes to continue generating a random number, and determining whether the crossover operation can be performed, wherein the crossover probability P in the optional embodiment _c =0.8. In the chromosome crossing process, both the crossing starting point position and the crossing length are randomly generated so as to improve the randomness of the population and avoid the algorithm from falling into local convergence. If the crossing is directly carried out according to the conventional genetic algorithm crossing principle, repeated coding point positions appear on one chromosome after the crossing is finished possiblyThe specific expression is that a certain measuring point of the workpiece is repeatedly measured, while certain measuring points are not measured, and the chromosome of the coding mode does not conform to the process of measuring stress of a sample stage of a neutron spectrometer.

Therefore, it is necessary to improve the above-mentioned crossing operation, avoid the duplicate point locations on the chromosome, and after determining the starting point location and the crossing length of the crossing, sequentially perform the crossing operation according to the order of the point locations. Firstly, the first point location is crossed, the other point locations are unchanged, and corresponding numbers on non-crossed positions are exchanged in the crossing process, so that repeated numbers do not appear on a chromosome after crossing; and by analogy, until the point position in the crossing length is crossed completely, repeated coding cannot occur on the whole chromosome at the moment, and the actual requirement is met.

(4) And (5) performing mutation operation. Generating a random number for each chromosome if the random number is greater than or equal to the mutation probability P _m Then any two positions are taken to exchange the coordinate numbers, P in this alternative embodiment _m And =0.3. This ensures that no repeated coding occurs on the chromosome after mutation.

(5) A fitness function. At present, the optimization problem with the minimum time as the optimization target usually selects the reciprocal of the time used by an individual as the fitness value of the individual, but the fitness value obtained in this way is not proportional to the time, which may cause instability in the solution process. Aiming at the embodiment of the invention, a fitness function shown as the following formula is designed:

wherein, the fitness (i) is the fitness value of the ith individual in the population; t (i) is the measurement time corresponding to the ith individual in the population; minT is the minimum value of the corresponding measurement time of all individuals in the population; maxT is the maximum value of the corresponding measurement time of all individuals in the population; epsilon is a small value to avoid the invalidity of the fitness function when maxT-minT =0, and epsilon =0.0001 in this embodiment.

(6) And (5) iteration termination condition. The genetic algorithm needs to specify an iteration termination condition in the iterative evolution process, and the currently commonly used iteration termination condition is as follows: presetting a maximum iteration number MAX in advance, counting an iteration number Gen in the iterative evolution process of the genetic algorithm, and if the iteration number Gen is greater than the maximum iteration number MAX, terminating the iteration; when the genetic algorithm reaches the optimal solution or falls into the local optimal solution in advance in the iterative evolution process, the iterative evolution can be continuously carried out under the limitation of the iterative termination condition, and the calculation efficiency is influenced.

Aiming at the defects of the iteration termination condition, the invention improves the original iteration termination condition. And setting the iteration frequency of the optimal fitness keeping unchanged as F, and presetting the maximum iteration frequency of the fitness keeping unchanged as MAX _ F. The iteration termination condition provided by the invention is as follows: and F is counted in the iterative evolution process of the genetic algorithm, and if the F is larger than MAX _ F, the iteration is terminated.

In summary, the iteration termination conditions of the present invention are: the genetic algorithm can terminate the iteration when the process of iterative evolution meets any condition of Gen > MAX and F > MAX _ F. Aiming at the improvement of the genetic algorithm, the whole process of the intelligent sequencing of the measured sample measuring points of the neutron spectrometer provided by the invention is used for explaining the embodiment, as shown in fig. 7. Specific steps are introduced as follows for the flowchart:

And 2, initializing the population. Initializing the parameter settings of the genetic algorithm: population number N, chromosome length M, maximum iteration number MAX _ F with constant optimal fitness, and cross probability P _c Probability of variation P _m (ii) a Importing the position and the direction information of a measured point of a workpiece; the chromosomes are encoded and the original population is randomly generated. In this alternative embodiment, the population number N =100, the chromosome length M =18, the maximum iteration number MAX =500, the maximum iteration number MAX _ F =50 with the optimal fitness remaining unchanged, and the cross probability P _c =0.8, probability of mutation P _m =0.3; the position and direction information of the measured point of the workpiece are shown in table 3.

And 3, calculating the fitness value of each chromosome in the population.

And 5, carrying out selection operation.

And 6, performing crossover operation.

And 7, performing mutation operation.

And 8, updating the iteration times.

After the above steps, the measurement sequence of 16 sets of measurement points in this alternative embodiment can be obtained as follows: 0- >13- >14- >15- >16- >9- >10- >11- >12- >1- >2- >3- >4- >8- >7- >6- >5- >0.

Wherein 0 represents the sample stage in situ, 1-16 represents the number of 16 sets of measuring points, and the sequence diagram of the measuring points is shown in FIG. 11. The total time required for completing the movement of the sample stage of the measurement task through the measurement sequence is as follows: for 146 seconds.

The convergence curve for solving the optimal measurement sequence in this embodiment is shown in fig. 12. From the convergence graph it can be seen that: the solution efficiency of the scheme on the optimal sequencing is high, and the optimal solution can be converged quickly. The figure shows that the time (optimal fitness) required by the movement of the sample stage is kept unchanged when the genetic algorithm is iterated to about 60 times, and if the iteration termination condition provided by the invention is used, the iteration process of the genetic algorithm can be terminated in advance, so that the calculation time is reduced, and the calculation efficiency is improved.

The embodiment provides the intelligent sequencing method for the measured sample measuring points of the neutron spectrometer, so that the traditional manual measuring point sequencing is replaced, the total moving time of a sample table is reduced, and the measuring efficiency is improved; the solution efficiency of the scheme on the optimal sequencing is high, the optimal solution can be quickly converged, and the technical effect is good.

In this embodiment, an electronic device is provided, comprising a memory in which a computer program is stored and a processor arranged to run the computer program to perform the method in the above embodiments.

The programs described above may be run on a processor or stored in memory (or referred to as computer-readable media), which includes both non-transitory and non-transitory, removable and non-removable media, that enable storage of information by any method or technology. The information may be computer readable instructions, data structures, modules of a program, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static Random Access Memory (SRAM), dynamic Random Access Memory (DRAM), other types of Random Access Memory (RAM), read Only Memory (ROM), electrically Erasable Programmable Read Only Memory (EEPROM), flash memory or other memory technology, compact disc read only memory (CD-ROM), digital Versatile Discs (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information that can be accessed by a computing device. As defined herein, a computer readable medium does not include a transitory computer readable medium such as a modulated data signal and a carrier wave.

These computer programs may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks, and corresponding steps may be implemented by different modules.

Such an apparatus or system is provided in this embodiment. The system is called a neutron spectrometer measured sample measuring point sequencing system, and comprises: the representing module is used for representing the coordinates of the measured point, the measured vector, the coordinates of the diffraction point and the scattering vector in the base coordinate system; the processing module is used for taking the minimum motion time of the sample stage as an objective function, wherein the objective function is used for indicating the motion time of returning to the initial position after the sample stage traverses and moves to each measuring point from the initial position, and the motion time is calculated according to the coordinates of the measured point, the measured vector, the coordinates of the diffraction point and the scattering vector; the iteration module is used for taking each measuring point sequencing scheme as a chromosome in a genetic algorithm, wherein each chromosome comprises all measuring points in different sequences, an initial point and an end point, and the initial point and the end point are points corresponding to the initial position; performing iterative operation on chromosomes according to the preset iterative times, wherein each iterative operation is to perform selection operation, crossover operation and mutation operation on the previous generation of chromosomes to obtain the next generation of chromosomes; the calculation module is used for calculating the corresponding fitness of each chromosome in each generation according to a fitness function until the fitness corresponding to the optimal individual in the obtained chromosome meets a preset condition, wherein the fitness function is established according to the target function; and the measuring point sequencing scheme corresponding to the optimal individual is used for measuring the measured sample.

The system or the apparatus is used for implementing the functions of the method in the foregoing embodiments, and each module in the system or the apparatus corresponds to each step in the method, which has been described in the method and is not described herein again.

The above embodiment has the following features: (1) The technical scheme provided by the embodiment can intelligently sequence the measuring points of the measured sample of the neutron spectrometer, replaces the traditional manual measuring point sequencing, and reduces the experiment preparation time; (2) By sequencing the measuring points of the measured sample of the neutron spectrometer through the technical scheme provided by the embodiment, the total moving time of the sample stage can be reduced by performing the test according to the programmed sequencing, and the measuring efficiency is improved; (3) The technical scheme provided by the embodiment is beneficial to realizing the automatic control of the sample stage of the neutron spectrometer; (4) The basic genetic algorithm is improved in the technical scheme of the embodiment, so that the solving efficiency of the genetic algorithm on the measurement intelligent sequencing problem of the measured sample of the neutron spectrometer can be improved, and the capability of converging to the optimal solution can be improved.

The above are merely examples of the present application and are not intended to limit the present application. Various modifications and changes may occur to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A method for sequencing measured sample measuring points of a neutron spectrometer is characterized by comprising the following steps:

the coordinates of a measured point, a measured vector, the coordinates of a diffraction point and a scattering vector are represented in a base coordinate system;

taking the minimum motion time of the sample stage as an objective function, wherein the objective function is used for indicating the motion time of the sample stage returning to the initial position after traversing and moving from the initial position to each measuring point, and the motion time is calculated according to the coordinates of the measured point, the measured vector, the coordinates of the diffraction point and the scattering vector;

taking each measuring point sequencing scheme as a chromosome in a genetic algorithm, wherein each chromosome comprises all measuring points in different sequences, an initial point and an end point, and the initial point and the end point are points corresponding to the initial position;

performing iterative operation on chromosomes according to the preset iterative times, wherein each iterative operation is to perform selection operation, crossover operation and mutation operation on the previous generation of chromosomes to obtain the next generation of chromosomes;

calculating the corresponding fitness of each chromosome in each generation according to a fitness function until the fitness corresponding to the optimal individual in the obtained chromosome meets a preset condition, wherein the fitness function is established according to the objective function; the measuring point sequencing scheme corresponding to the optimal individual is used for measuring the measured sample;

wherein the objective function is:

；

wherein p is ₀ Denotes the initial position of the sample stage, R = (p) ₁ ,p ₂ ,…,p _N ) For a set of all measured points, N represents the number of measured points, (p) _a1 ,p _a2 ,…,p _aN ) Representing the final measured point sequencing scheme satisfying the objective function in R (a) ₁ ,a ₂ …,a _N ) Denotes a non-repeating number within the range 1~N,

representing the measured point

representing the measured point

Measuring the time required by the sample platform to return to the initial position after the measurement is finished;

the fitness function is:

wherein, the fitness (j) is the fitness value of the jth individual in the population; t (j) is the measuring time corresponding to the jth individual in the population; minT is the minimum value of the corresponding measuring time of all individuals in the population; maxT is the maximum value of the corresponding measurement time of all individuals in the population; epsilon is a preset value to avoid the fitness function being invalid when maxT-minT =0.

2. The method of claim 1, wherein iteratively operating on the chromosome comprises:

each iteration operation is to perform selection operation, crossover operation and mutation operation on the previous generation of chromosomes to obtain the next generation of chromosomes.

3. The method of claim 2, wherein the selecting operation comprises:

the fitness value of each individual in the population of the generation is arranged from large to small, wherein b ₁ 、b _n Respectively the maximum and minimum fitness value in the population, and the fitness b ₁ Multiplying by the reward factor omega ₁ (ii) a Degree of adaptation b _n Multiplying by a penalty factor omega ₂ (ii) a Wherein, ω is ₁ >1，0<ω ₂ <1。

4. The method of claim 2, wherein the interleaving operation comprises:

generating a random number for a pair of chromosomes, if the random number is greater than or equal to the crossover probability P _c And performing crossover operation, otherwise, reselecting a pair of chromosomes from the rest chromosomes to continuously generate a random number, and judging whether crossover operation can be performed.

5. The method of claim 2, wherein the mutation operation comprises:

generating a random number for each chromosome if the random number is greater than or equal to the mutation probability P _m Any two locations are swapped for the coordinate number.

6. The method of claim 1, wherein the predetermined condition being met comprises:

acquiring a preset maximum iteration number MAX, counting an iteration number Gen in the process of iterative evolution, and if the iteration number Gen is greater than the maximum iteration number MAX, terminating iteration; or, setting the iteration number of which the optimal fitness keeps unchanged as F, acquiring the maximum preset iteration number of which the fitness keeps unchanged as MAX _ F, counting F in the iterative evolution process, and if F is greater than MAX _ F, terminating iteration.

7. A sequencing system for measured sample measuring points of a neutron spectrometer is characterized by comprising:

the representing module is used for representing the coordinates of the measured point, the measured vector, the coordinates of the diffraction point and the scattering vector in the base coordinate system;

the processing module is used for taking the minimum motion time of the sample stage as an objective function, wherein the objective function is used for indicating the motion time of returning to the initial position after the sample stage traverses and moves to each measuring point from the initial position, and the motion time is calculated according to the coordinates of the measured point, the measured vector, the coordinates of the diffraction point and the scattering vector;

the iteration module is used for taking each measuring point sequencing scheme as a chromosome in a genetic algorithm, wherein each chromosome comprises all measuring points in different sequences, an initial point and an end point, and the initial point and the end point are points corresponding to the initial position; performing iterative operation on chromosomes according to the preset iterative times, wherein each iterative operation is to perform selection operation, crossover operation and mutation operation on the previous generation of chromosomes to obtain the next generation of chromosomes;

the calculation module is used for calculating the corresponding fitness of each chromosome in each generation according to a fitness function until the fitness corresponding to the optimal individual in the obtained chromosome meets a preset condition, wherein the fitness function is established according to the target function; the measuring point sequencing scheme corresponding to the optimal individual is used for measuring the measured sample;

wherein the objective function is:

；

wherein p is ₀ Denotes the initial position of the sample stage, R = (p) ₁ ,p ₂ ,…,p _N ) For a set of all measured points, N represents the number of measured points, (p) _a1 ,p _a2 ,…,p _aN ) Representing the final measured point sequencing scheme satisfying the objective function in R (a) ₁ ,a ₂ …,a _N ) Denotes a non-repeating number within the range of 1~N,

representing the measured point

representing the measured point

The sample platform returns to the position after the measurement is finishedTime required for initial position;

the fitness function is:

wherein, the fitness (j) is the fitness value of the jth individual in the population; t (j) is the measuring time corresponding to the jth individual in the population; minT is the minimum value of the corresponding measurement time of all individuals in the population; maxT is the maximum value of the corresponding measurement time of all individuals in the population; epsilon is a preset value to avoid the fitness function being invalid when maxT-minT =0.