CN114735140B - Disturbance speed compensation method, equipment and medium for wind power pile boarding trestle bridge - Google Patents

Abstract

The invention provides a method, equipment and medium for compensating the interference speed of a wind power pile boarding trestle. According to the method, the interference speed (ship motion speed) compensation mode is introduced and is combined with the interference position compensation, so that the rapidity and the compensation effect of the active motion compensation trestle are improved, the use experience of the trestle lapping process is improved, the accessibility of the wind power pile in severe weather is improved, and the safety of passengers is improved.

Description

Disturbance speed compensation method, equipment and medium for wind power pile boarding trestle bridge

technical field

The invention belongs to the technical field of offshore wind power boarding and boarding trestles with wave compensation function, and in particular relates to a method, equipment and medium for compensating the disturbance speed of wind power pile boarding and boarding trestles. Specifically, it is a control method for compensating the speed of the ship to improve the accuracy of the motion compensation and realize the smooth lapping of the trestle bridge under high sea conditions.

Background technique

Wind energy is clean and renewable energy. Compared with land wind power generation, offshore wind power has the advantages of not occupying land area and having little impact on birds. In addition, offshore wind power also has the advantages of less quiet wind period and strong wind force. my country has abundant wind energy in both offshore and COSCO seas, and the development of offshore wind power is of great significance to optimize my country's energy structure.

However, installation and maintenance costs of offshore wind power are higher than onshore wind power. In severe weather conditions, the violent shaking of the operation and maintenance ship makes it difficult and dangerous for the operation and maintenance personnel to board the wind power pile. The active motion compensation (Active Motion Compensation, AMC) trestle makes the end of the trestle stay still relative to the earth coordinate system (the wind power pile fixed on the ground) or reduces the influence of waves on the motion of the ship by compensating the ship motion of certain degrees of freedom. Improve the accessibility of personnel to wind power piles in severe weather.

The three-degree-of-freedom AMC trestle bridge is shown in Figure 1, and it is mainly composed of (B1) base, (B2) support, (B3) pitch bridge, (B4) telescopic bridge and (B5) insert plate at the end of the telescopic bridge. After the insertion plate is inserted into the foundation ladder of the wind turbine platform, maintenance personnel reach the ladder through the support, pitch bridge and telescopic bridge, and board the offshore wind turbine platform. According to the requirements of safety regulations, only when the distance between the operation and maintenance ship and the ladder of offshore wind turbines does not exceed half the step length of an adult can one board the ladder of the wind power platform. However, the impact of sea tides and waves will cause a certain distance between the ship and the ladder of the offshore wind power platform in the vertical direction and the horizontal direction, and the distance will change with the shaking of the ship.

The motion measurement unit installed on the ship will measure the motion of the ship's six degrees of freedom, and compensate the ship's yaw, pitch and yaw through the (Y1) rotary hydraulic cylinder, (Y2) pitch hydraulic cylinder and (Y3) telescopic hydraulic cylinder The oscillating motion causes the displacement change of (B5) inserting plate relative to the ladder. At the same time, the entire trestle can also maintain a relatively stable state.

When the wind and waves on the sea are small, the operator can turn off the active motion compensation function, and control the proportional valve group through the operating handle to control the movement speed of the slewing, pitching and telescopic hydraulic cylinder piston rod, which can smoothly make the insertion plate at the end of the telescopic bridge Insert the ladder to complete the establishment of the personnel passage. In the case of strong wind and waves, the insertion plate at the end of the telescopic bridge will amplify the shaking of the ship, making the process of inserting the ladder difficult. At this time, it is necessary to turn on the active compensation function to eliminate or reduce the influence of the ship's shaking on the plug-in board. When the operating handle does not move, the coordinates at the end of the plug-in board remain static relative to the earth coordinate system or reduce the influence of the ship's motion. In order to complete active motion compensation, it is necessary to use the motion reference unit (MotionReference Unit, MRU) to measure the motion of the ship in six degrees of freedom, and then calculate the compensation amount of the trestle in the rotation degree of freedom, pitching degree of freedom and telescopic degree of freedom through the transformation matrix , to compensate for the motion of the ship in the yaw, pitch and heave directions. In order to keep the insertion board stationary relative to the earth coordinate system, the active motion compensation trestle needs to compensate the position change of the insertion board caused by the ship's motion, so the control of the trestle in the three degrees of freedom of rotation, pitch and telescopic is a position servo system, according to The position error is used to control the extension of the piston rod of the hydraulic cylinder. However, this compensation method mainly has the following problems in the process of active motion compensation:

(1) Due to the randomness of ship motion, the sampling delay of MRU, the limitation of hydraulic cylinder motion speed, the mechanical clearance of trestle installation, etc., during the working process of active motion compensation trestle, for relatively high-frequency ship motion, only rely on the measured Compensating the position of the ship will cause tracking lag and the compensation effect is not good.

(2) In the process of inserting the operating handle to drive the insertion plate into the foundation ladder of the wind turbine platform under high sea conditions, only the speed control of the operating handle and the position control of active motion compensation are simply superimposed, and the operation when the compensation function is closed under calm seas cannot be obtained. The experience of the handle process is consistent, and the operation is not smooth.

Contents of the invention

The purpose of the present invention is to solve the problems in the prior art, and propose a method, device and medium for compensating the disturbance speed of a wind power pile boarding trestle. The present invention combines the interference position compensation with the introduction of interference speed (ship motion speed) compensation to improve the rapidity and compensation effect of active motion compensation trestles, improve the use experience of the trestle lapping process, and improve the efficiency of wind power piles in bad weather. accessibility, increasing the safety of boarding personnel.

The present invention is achieved through the following technical solutions. The present invention proposes a method for compensating the disturbance speed of a wind power pile boarding trestle. The method specifically includes the following steps:

Step 1. Set the position of the plug-in board as x=[x ₁ , x ₂ , x ₃ ] ^T , where x ₁ , x ₂ , and x ₃ are the coordinate values of the plug-in board in the three coordinate axes of the earth coordinate system O-XYZ respectively, Then the coordinate value is expressed as:

In the formula, A, B, C and D are system matrices, u(k)=[r(k), p(k), s(k)] ^T are the rotation value, pitch value and telescopic value of the trestle respectively; d (k)=[r _s (k), p _s (k), h _s (k)] ^T are the yaw value, pitch value and heave value of the ship respectively, the output value y=[x ₁ ,x ₂ ,x ₃ ] ^T , k represents time series;

Step 2, change the equation (1) into a differential form, set the objective function J(k) that covers the position and speed tracking error, and determine the increment of the control amount through the objective function;

Step 3. Obtain the increment of the ship motion disturbance through the extended state observer ESO;

Step 4, the final control quantity is obtained by integrating the control quantity increment and the disturbance quantity increment;

此时的控制量用来补偿船舶运动导致的插入板坐标的变化；当操作手柄动作时，插入板的目标速度

与操作手柄的输出电压成比例，x_r(k)为

的积分，以跟踪手柄的操作。Step 5. Record the system state at the moment when the AMC function is turned on as x(0). When the operating handle does not move, the target position of the plug-in board x _r (k)=x(0), and the target speed of the plug-in board

The control amount at this time is used to compensate the change of the coordinates of the insertion board caused by the movement of the ship; when the operating handle is moved, the target speed of the insertion board

Proportional to the output voltage of the operating handle, x _r (k) is

points to track controller operations.

Further, transform equation (1) into differential form:

分别为状态量、控制量和干扰量的增量；系统矩阵中

O为零矩阵，I为单位矩阵。In the formula,

are the increments of the state quantity, control quantity and disturbance quantity respectively; in the system matrix

O is the zero matrix and I is the identity matrix.

Further, considering the amplitude constraint and speed constraint of the control variable u(k), the increment of the control variable is obtained by solving the following objective function:

代表状态误差，x_r(k)为插入板的目标位置，x^d(k)为x(k)的微分即插入板的速度，因此误差中既包含了位置误差也包含了速度误差；

为控制量增量，增加的自由度

用来模拟干扰量的增量。In the formula, N _p is the prediction time domain, the matrices Q and S are semi-positive definite matrices, and the matrices R and P are positive definite matrices,

Represents the state error, x _r (k) is the target position of the inserted board, x ^d (k) is the differential of x(k), which is the speed of the inserted board, so the error includes both position error and speed error;

For the control volume increment, the increased degrees of freedom

The increment used to simulate the amount of disturbance.

Further, minimize the objective function J(k) to obtain the following control sequence:

Therefore, solving the objective function problem at each sampling period can be transformed into the following quadratic programming:

Subject to Lη≤b

In the formula, L and b are used to limit the amplitude and speed of the control variable; the matrices F and H are defined as follows and obtained by real-time calculation:

可表示为：state

Can be expressed as:

同时，也可以获得优化的干扰值增量

因此控制量增量可以通过下式获得：Further, using formula (5) to optimize η ^* in real time, the optimal value of the control increment can be obtained

At the same time, an optimized disturbance value increment can also be obtained

Therefore, the control increment can be obtained by the following formula:

其通过

获得；最小化误差E(k)，μ(k)满足In the formula, μ(k) is used to compensate the disturbance

its passing

Obtain; minimize the error E(k), μ(k) satisfies

是干扰的估计值，同时μ(k)通过下式计算：In the formula,

is the estimated value of the disturbance, while μ(k) is calculated by:

的估计值

采用如下的扩张状态观测器ESO 来观测干扰：Further, in order to obtain the interference amount increment

estimated value of

The following extended state observer ESO is used to observe the disturbance:

代表*的估计值，

代表x微分的估计值，

代表x二次微分的估计值；T_s为采样周期，θ是观测器增益，k_o1,k_o2,k_o3和k_o4为观测器系数；函数g_i(i＝1,2,3,4) 表示为：In the formula,

represents the estimated value of *,

represents an estimate of the x-differentiation,

Represents the estimated value of the quadratic differential of x; T _s is the sampling period, θ is the observer gain, k _o1 , k _o2 , k _o3 and k _o4 are the observer coefficients; the function g _i (i=1,2,3,4 ) Expressed as:

并通过式(9)计算μ(k)；进而优化的控制变量为In the formula, α ₁ = γ, α ₂ = 2γ-1, α ₃ = 3γ-2, α ₄ = 4γ-3, γ∈(3/4,1); K is a positive definite matrix; based on formula (10) for The estimate of d(k), obtains

And calculate μ(k) through formula (9); then the optimized control variable is

即Further, through the stroke of the hydraulic cylinder and the mechanical structure, the maximum and minimum values of the control quantities determined are u _sU and u _sL respectively; the maximum and minimum values of the control quantity increments determined by the flow rate of the proportional valve are respectively

Right now

μ(k) in Equation (9) can be re-described as:

因此控制量的幅值约束可采用如下不等式表示：In the formula,

Therefore, the magnitude constraint of the control quantity can be expressed by the following inequality:

In the formula,

Similarly, the constraint on the increment of the control quantity can be expressed by the following inequality:

和

分别为

和

的增量；In the formula,

and

respectively

and

increment;

The present invention proposes an electronic device, including a memory and a processor. The memory stores a computer program. When the processor executes the computer program, the steps of the method for compensating the disturbance speed of a wind power pile boarding trestle are realized.

The present invention proposes a computer-readable storage medium for storing computer instructions, and when the computer instructions are executed by a processor, the steps of the disturbance speed compensation method for wind power pile boarding trestles are realized.

The beneficial effects of the present invention are:

(1) Adopting the differential form of the trestle model, and adding the tracking speed error to the error, the rapidity and dynamic compensation accuracy of active motion compensation are improved;

(2) Use the value proportional to the output voltage of the operating handle as the tracking speed, and use the integral of the tracking speed as the target position to improve the operating experience of the handle;

(3) The speed limit of the hydraulic cylinder movement and the position constraint of the trestle bridge are considered in the solution control of the control quantity, so that the obtained control quantity is a physically feasible control, avoiding the emergency braking caused by limiting the movement amplitude by the limit switch, and ensuring The smoothness of movement in extreme positions is guaranteed.

Description of drawings

Figure 1 is a schematic diagram of the composition of the AMC trestle; among them, Y1 rotary hydraulic cylinder; Y2 pitch hydraulic cylinder; Y3 telescopic hydraulic cylinder; B1 base; B2 support; B3 pitch bridge; B4 telescopic bridge; B5 insert plate;

Figure 2 is a schematic diagram of the trestle bridge lapped with wind power piles; among them, B4 telescopic bridge; B5 insert plate; C1 wind turbine platform; C2 ladder;

Figure 3 is a functional block diagram of disturbance speed compensation.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Combining with Fig. 1-Fig. 3, the present invention proposes a method for compensating the interference speed of the wind power pile boarding trestle bridge. The lapping process of the trestle bridge is shown in Fig. 2. The insertion board is inserted into the foundation ladder of the wind turbine platform to complete the establishment of the personnel passage; Described method specifically comprises the following steps:

Step 1. Set the position of the plug-in board as x=[x ₁ , x ₂ , x ₃ ] ^T , where x ₁ , x ₂ , and x ₃ are the coordinate values of the plug-in board in the three coordinate axes of the earth coordinate system O-XYZ respectively, Then the coordinate value is expressed as:

In the formula, A, B, C and D are system matrices, u(k)=[r(k), p(k), s(k)] ^T are the rotation value, pitch value and telescopic value of the trestle respectively; d (k)=[r _s (k), p _s (k), h _s (k)] ^T are the yaw value, pitch value and heave value of the ship respectively, the output value y=[x ₁ ,x ₂ ,x ₃ ] ^T , k represents time series;

Step 2, in order to deal with the fast-changing ship motion, change the equation (1) into a differential form, set the objective function J(k) that covers the position and velocity tracking error, and determine the increment of the control amount through the objective function;

Step 3. Obtain the increment of the ship motion disturbance through the extended state observer ESO;

Step 4, the final control quantity is obtained by integrating the control quantity increment and the disturbance quantity increment;

此时的控制量用来补偿船舶运动导致的插入板坐标的变化，误差中包含了速度误差；当操作手柄动作时，插入板的目标速度

与操作手柄的输出电压成比例，x_r(k)为

的积分，以跟踪手柄的操作。当操作手柄时，式(3)中插入板的目标位置

(数字控制系统中以累加和代替积分值)，插入板末端的目标速度

(v_r为操作手柄三个自由度的输出电压，k_v为比例系数)。此时的控制量除了用来补偿船舶运动导致的插入板坐标的变化，还同时响应手柄的操作。通过调整k_v获得与通过v_r直接控制比例阀开口一致的速度，使手柄操作更加平顺，改善开启AMC功能后手柄的操作体验。Step 5. Record the system state at the moment when the AMC function is turned on as x(0). When the operating handle does not move, the target position of the plug-in board x _r (k)=x(0), and the target speed of the plug-in board

The control amount at this time is used to compensate the change of the coordinates of the insertion board caused by the movement of the ship, and the error includes the speed error; when the operating handle is moved, the target speed of the insertion board

Proportional to the output voltage of the operating handle, x _r (k) is

points to track controller operations. When the handle is operated, the target position of the insertion plate in equation (3)

(In the digital control system, the cumulative sum is used instead of the integral value), insert the target speed at the end of the board

(v _r is the output voltage of the three degrees of freedom of the operating handle, and k _v is the proportional coefficient). The control quantity at this time is not only used to compensate the change of the coordinates of the insertion board caused by the movement of the ship, but also responds to the operation of the handle at the same time. By adjusting k _v to obtain the same speed as directly controlling the opening of the proportional valve through v _r , the handle operation is smoother, and the operating experience of the handle after the AMC function is turned on is improved.

Put equation (1) into differential form:

分别为状态量、控制量和干扰量的增量；系统矩阵中

O为零矩阵，I为单位矩阵。In the formula,

are the increments of the state quantity, control quantity and disturbance quantity respectively; in the system matrix

O is the zero matrix and I is the identity matrix.

Considering the magnitude constraint and speed constraint of the control variable u(k), the increment of the control variable is obtained by solving the following objective function:

代表状态误差，x_r(k)为插入板的目标位置，x^d(k)为x(k)的微分即插入板的速度，因此误差中既包含了位置误差也包含了速度误差；

为控制量增量，增加的自由度

用来模拟干扰量的增量。In the formula, N _p is the prediction time domain, the matrices Q and S are semi-positive definite matrices, and the matrices R and P are positive definite matrices,

Represents the state error, x _r (k) is the target position of the inserted board, x ^d (k) is the differential of x(k), which is the speed of the inserted board, so the error includes both position error and speed error;

For the control volume increment, the increased degrees of freedom

The increment used to simulate the amount of disturbance.

The objective function includes the speed error and the increment of the disturbance (equivalent to the disturbance speed), so it can reflect the rapidly changing ship motion.

Minimize the objective function J(k) to obtain the following control sequence:

Therefore, solving the objective function problem at each sampling period can be transformed into the following quadratic programming:

Subject to Lη≤b

In the formula, L and b are used to limit the amplitude and speed of the control variable; the matrices F and H are defined as follows and obtained by real-time calculation:

可表示为：state

Can be expressed as:

同时，也可以获得优化的干扰值增量

因此控制量增量可以通过下式获得：Using formula (5) to optimize η ^* in real time, the optimal value of control quantity increment can be obtained

At the same time, an optimized disturbance value increment can also be obtained

Therefore, the control increment can be obtained by the following formula:

其通过

获得；最小化误差E(k)，μ(k)满足In the formula, μ(k) is used to compensate the disturbance

its passing

Obtain; minimize the error E(k), μ(k) satisfies

是干扰的估计值，同时μ(k)通过下式计算：In the formula,

is the estimated value of the disturbance, while μ(k) is calculated by:

的估计值

采用如下的扩张状态观测器ESO来观测干扰：In order to obtain the amount of interference increment

estimated value of

The following extended state observer ESO is used to observe the disturbance:

代表*的估计值，

代表x微分的估计值，

代表x二次微分的估计值；T_s为采样周期，θ是观测器增益，k_o1,k_o2,k_o3和k_o4为观测器系数；函数g_i(i＝1,2,3,4) 表示为：In the formula,

represents the estimated value of *,

represents an estimate of the x-differentiation,

Represents the estimated value of the quadratic differential of x; T _s is the sampling period, θ is the observer gain, k _o1 , k _o2 , k _o3 and k _o4 are the observer coefficients; the function g _i (i=1,2,3,4 ) Expressed as:

并通过式(9)计算μ(k)；进而优化的控制变量为In the formula, α ₁ = γ, α ₂ = 2γ-1, α ₃ = 3γ-2, α ₄ = 4γ-3, γ∈(3/4,1); K is a positive definite matrix; based on formula (10) for The estimate of d(k), obtains

And calculate μ(k) through formula (9); then the optimized control variable is

即According to hydraulic cylinder stroke and mechanical structure, the maximum and minimum values of control quantity determined are u _sU and u _sL respectively; the maximum and minimum values of control quantity increment determined by proportional valve flow are respectively

Right now

μ(k) in Equation (9) can be re-described as:

因此控制量的幅值约束可采用如下不等式表示：In the formula,

Therefore, the magnitude constraint of the control quantity can be expressed by the following inequality:

In the formula,

Similarly, the constraint on the increment of the control quantity can be expressed by the following inequality:

和

分别为

和

的增量；In the formula,

and

respectively

and

increment;

As shown in Fig. 3, the system of the active motion compensation method based on disturbance speed compensation of the present invention includes an operating handle integration unit, a quadratic programming unit, a control quantity calculation unit, an extended state observer unit, a trestle controlled object and an MRU.

The present invention proposes an electronic device, including a memory and a processor. The memory stores a computer program. When the processor executes the computer program, the steps of the method for compensating the disturbance speed of a wind power pile boarding trestle are realized.

The present invention proposes a computer-readable storage medium for storing computer instructions, and when the computer instructions are executed by a processor, the steps of the disturbance speed compensation method for wind power pile boarding trestles are implemented.

The above has introduced in detail the disturbance speed compensation method, equipment and medium of a wind power pile boarding trestle proposed by the present invention. In this paper, specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments It is only used to help understand the method of the present invention and its core idea; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation and scope of application. In summary, The contents of this description should not be construed as limiting the present invention.

Claims (4)

1. A method for compensating the disturbance speed of a wind power pile boarding trestle bridge, characterized in that, the method specifically comprises the following steps: Step 1. Set the position of the plug-in board as x=[x ₁ , x ₂ , x ₃ ] ^T , where x ₁ , x ₂ , and x ₃ are the coordinate values of the plug-in board in the three coordinate axes of the earth coordinate system O-XYZ respectively, Then the coordinate value is expressed as:

In the formula, A, B, C and D are system matrices, u(k)=[r(k), p(k), s(k)] ^T are the rotation value, pitch value and telescopic value of the trestle respectively; d (k)=[r _s (k), p _s (k), h _s (k)] ^T are the yaw value, pitch value and heave value of the ship respectively, the output value is y(k), and k represents Time series; u(k) is the control variable, d(k) is the interference quantity; Step 2. Change the equation (1) into a differential form, set an objective function J(k) including position and speed tracking errors, and determine the increment of the control quantity through the objective function; Step 3. Obtain the increment of the ship motion disturbance through the extended state observer ESO; Step 4, the final control quantity is obtained by integrating the control quantity increment and the disturbance quantity increment; Step 5. Record the system state at the moment when the active motion compensation AMC function is turned on as x(0). When the operating handle does not move, the target position of the insertion board x _r (k)=x(0), and the target speed of the insertion board

The control amount at this time is used to compensate the change of the coordinates of the insertion board caused by the movement of the ship; when the operating handle is moved, the target speed of the insertion board

Proportional to the output voltage of the operating handle, x _r (k) is

points to track the operation of the controller; Put equation (1) into differential form:

In the formula,

are the increments of the state quantity, control quantity and disturbance quantity respectively; in the system matrix

O is a zero matrix, and I is an identity matrix; Considering the magnitude constraint and speed constraint of the control variable u(k), the increment of the control variable is obtained by solving the following objective function:

In the formula, N _p is the prediction time domain, the matrices Q and S are semi-positive definite matrices, and the matrices R and P are positive definite matrices,

Represents the state error, x _r (k) is the target position of the plug-in board, x ^d (k) is the differential of x(k), which is the speed of the plug-in board, so the error includes both position error and speed tracking error;

For the control volume increment, the increased degrees of freedom

Increment used to simulate the amount of disturbance; Minimize the objective function J(k) to obtain the following control sequence:

Therefore, solving the objective function problem at each sampling period is transformed into the following quadratic programming:

In the formula, L and b are used to limit the amplitude and speed of the control variable; the matrices F and H are defined as follows and obtained by real-time calculation:

state

Expressed as:

Use formula (5) to optimize η ^* in real time to obtain the optimal value of the control quantity increment

At the same time, an optimized disturbance value increment is obtained

Therefore, the control quantity increment is obtained by the following formula:

In the formula, μ(k) is used to compensate the disturbance

its passing

Obtain; minimize the error E(k), μ(k) satisfies

In the formula,

is the estimated value of the disturbance, while μ(k) is calculated by:

In order to obtain the amount of interference increment

estimated value of

The following extended state observer ESO is used to observe the disturbance:

In the formula,

represents the estimated value of *,

represents an estimate of the x-differentiation,

Represents the estimated value of the quadratic differential of x; T _s is the sampling period, θ is the observer gain, k _o1 , k _o2 , k _o3 and k _o4 are the observer coefficients; the function g _i (i=1,2,3,4 )Expressed as:

In the formula, α ₁ = γ, α ₂ = 2γ-1, α ₃ = 3γ-2, α ₄ = 4γ-3, γ∈(3/4,1); K is a positive definite matrix; based on formula (10) for The estimate of d(k), obtains

And calculate μ(k) through formula (9); then the optimized control variable is

2. The method according to claim 1, characterized in that, through the stroke of the hydraulic cylinder and the mechanical structure, the maximum and minimum values of the control quantities are determined to be u _sU and u _sL respectively; the maximum and minimum increments of the control quantities are determined by the proportional valve flow Values are

Right now

μ(k) in (9) is re-described as:

In the formula,

Therefore, the amplitude constraint of the control quantity is expressed by the following inequality:

In the formula,

Similarly, the constraint on the increment of the control quantity is expressed by the following inequality:

In the formula,

and

respectively

and

increment;

3. An electronic device, comprising a memory and a processor, wherein the memory stores a computer program, wherein the processor implements the steps of the method according to any one of claims 1-2 when executing the computer program. 4. A computer-readable storage medium for storing computer instructions, wherein the steps of the method according to any one of claims 1-2 are implemented when the computer instructions are executed by a processor.

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