A method and device for constructing a magnetic guide wire deflection control model

Abstract

This invention discloses a method and apparatus for constructing a magnetic guide wire deflection control model. The method includes: obtaining the clockwise and counterclockwise deflection angles and displacements of a magnetic guide wire with a head end composed of magnetic powder in the x, y, and z planes under a uniform magnetic field; performing normality analysis on the collected data through a local analysis layer; establishing a linear regression equation between the deflection angle, deflection displacement, and magnetic field strength after confirming that the data are all normally distributed; inputting this equation into a global analysis layer to determine its normality, significance, and interpretability; inputting this equation into a feedback analysis layer to determine its universality; and obtaining the final deflection control model based on the determination results. This invention can obtain deflection control equations with accuracy, interpretability, normality, and universality, enabling precise control of the magnetic guide wire by a magnetic navigation surgical robot.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of control model construction methods, and particularly relates to a control model construction method for controlling the deflection process of a magnetic guide wire. BACKGROUND

[0002] When a magnetic navigation surgical robot is used to assist in minimally invasive surgery, a specially designed guide wire with a permanent magnet or a ferromagnetic object at the distal end is usually used. When the magnetic guide wire enters the human body, it needs to pass through a series of blood vessel bifurcations before reaching the lesion site. In this process, the turning of the head end of the guide wire is mainly realized by external magnetic field induction, such as controlling the gradient change of the magnetic field space generated by a large magnet at the torso of the patient, and controlling the angle and distance of the external magnet, so that the force acting on the distal end magnet of the guide wire changes, and the distal end magnet changes direction accordingly, thereby achieving the purpose of guiding the distal end of the magnetic guide wire. The above control process puts forward very high requirements for the control accuracy of the magnetic navigation surgical robot. However, due to the slender and smooth structure of the magnetic guide wire, unintentional collisions with tools or human tissues during its movement, periodic respiratory movements of the human body, and unpredictable body movements, it has always been a technical problem in clinical practice to achieve precise control of the magnetic guide wire, especially in its deflection.

[0003] A common means to solve the above technical problems in the prior art is to use theoretical derivation to establish a related control equation for the magnetic guide wire in the blood vessel, and to achieve high-precision control according to the control equation.

[0004] For example, the prior art document [1] discloses a method for deriving a magnetic field decay equation of a neodymium iron boron permanent magnet that changes with distance. The magnetic field decay equation obtained by this method can calculate the magnetic field strength acting on the magnetic guide wire in the blood vessel, but it can only theoretically calculate the magnetic field strength and magnetic moment applied to the head end of the magnetic guide wire, and cannot construct the motion mapping relationship between the deflection angle of the magnetic guide wire and the magnetic strength. Therefore, the operator can only control the distance between the neodymium iron boron permanent magnet and the magnetic guide wire by experience or intuition, and it is difficult to achieve precise control.

[0005] The prior art document [2] proposes a nonlinear theory applicable to magnetic guide wires, which can predict the deformation of the magnetic guide wire caused by the magnetic moment under the external magnetic field, but this theory obviously ignores the gravity and other factors acting on the magnetic guide wire, which does not conform to the actual clinical situation.

[0006] The prior art document [3] proposes a method for obtaining a correlation equation between the magnetic field and the deformation of the magnetic guide wire according to a customized neodymium iron boron permanent magnet gradient coil, but it cannot directly obtain the deflection control model of the magnetic guide wire under a uniform magnetic field, and it is also not applicable to magnetic guide wires formed by magnetizable magnetic powder.

[0007] The above cited documents are as follows:

[0008] [1] Kim Y, Genevriere E, Harker P, et al. Telerobotic neurovascular interventions with magnetic manipulation [J]. Science Robotics, 2022, 7(65): eabg9907.

[0009] [2] Wang L, Kim Y, Guo C F, et al. Hard-magnetic elastica [J]. Journal of the Mechanics and Physics of Solids, 2020, 142: 104045.

[0010] [3] Jeon S, Hoshiar A K, Kim K, et al. A magnetically controlled soft microrobot steering a guidewire in a three-dimensional phantom vascular network [J]. Soft robotics, 2019, 6(1): 54-68. SUMMARY

[0011] In view of the defects of the prior art, the purpose of the present application is to provide a method and device for directly constructing a deflection control model of a magnetic guidewire formed by magnetic powder under a uniform magnetic field.

[0012] The technical solution of the present application is as follows:

[0013] A construction device of a magnetic guidewire deflection control model, comprising: a Helmholtz coil composed of three pairs of mutually orthogonal coils, i.e. x coils, y coils and z coils, a magnetic guidewire, a transparent container horizontally placed at the center of the Helmholtz coil, a magnetic guidewire manipulation system capable of providing varying current to the Helmholtz coil and recording data of deflection of the magnetic guidewire under the influence of the Helmholtz coil, and bionic blood capable of being loaded into the transparent container, one end of the magnetic guidewire being fixed at the center of the bottom surface of the transparent container.

[0014] According to some preferred embodiments of the present application, the magnetic guidewire steering system comprises: a computer, a signal generator connected to the computer, a power amplifier connected to the signal generator and the Helmholtz coil, and a photographing device connected to the computer and capable of collecting the magnetic guidewire deflection image.

[0015] The present application further provides a method for constructing a magnetic guidewire deflection control model based on the above-mentioned construction device, which comprises:

[0016] By providing varying currents to the x coil, y coil and z coil of the Helmholtz coil respectively by the magnetic guidewire steering system, a plurality of sets of deflection data of the magnetic guidewire in the x plane corresponding to the x coil, the y plane corresponding to the y coil and the z plane corresponding to the z coil under the uniform magnetic field generated by the Helmholtz coil are obtained, wherein the deflection data comprises clockwise and counterclockwise deflection angles and deflection displacements of the magnetic guidewire;

[0017] The collected deflection data and corresponding magnetic field intensity input data are input into a local analysis layer of a data analysis model, and normal analysis of the deflection angle, deflection displacement and magnetic field intensity is performed by the local analysis layer. After confirming that the deflection angle, deflection displacement and magnetic field intensity are normally distributed, linear regression equations of the clockwise and counterclockwise deflection angles, deflection displacements and magnetic field intensities in the x plane, y plane and z plane are established as initial control equations of the magnetic guidewire;

[0018] The initial control equations output by the local analysis layer are input into a global analysis layer of the data analysis model, and normality, significance and interpretability of the initial control equations are determined by the global analysis layer. After the initial control equations possess normality, significance and interpretability, the initial control equations are used as basic control equations of the magnetic guidewire;

[0019] The process of obtaining the deflection data is repeated several times to obtain new sets of deflection data, which are used as verification data in a verification data set. Then, the basic control equations output by the global analysis layer and the verification data set are input into a feedback analysis layer of the data analysis model, and the universality of the basic control equations relative to the verification data is determined by the feedback analysis layer. After the basic control equations meet the universality requirement, the basic control equations are used as a final deflection control model of the magnetic guidewire.

[0020] According to some preferred embodiments of the present application, the universality is characterized by a root mean square error (RMSE).

[0021] Further preferably, when the root mean square error (RMSE) is within the range of [0, 3], it is considered that the basic control equations meet the universality requirement.

[0022] According to some preferred embodiments of the present application, the normal analysis performed by the local analysis layer is realized by using the Shapiro-Wilk test.

[0023] According to some preferred embodiments of the present application, the normality determination by the overall analysis layer is implemented using a Shapiro-Wilk test.

[0024] According to some preferred embodiments of the present application, the significance determination by the overall analysis layer is implemented using an F-test.

[0025] According to some preferred embodiments of the present application, the explainability determination by the overall analysis layer is implemented using a T-test.

[0026] According to some preferred embodiments of the present application, the varying current is generated by a current model: C = ±P*|sin(t)|, wherein C represents the working current, P represents the current amplitude, t represents the time, + represents the clockwise direction, and - represents the counterclockwise direction.

[0027] According to some preferred embodiments of the present application, the obtaining of the plurality of sets of deflection data comprises: providing currents to the x coil, y coil, and z coil according to the current model by the magnetic guide wire steering system at current amplitudes that vary discretely in a gradient, recording the deflection angle and deflection displacement generated by the magnetic guide wire at each current amplitude, and obtaining the plurality of sets of deflection data.

[0028] According to some preferred embodiments of the present application, the construction method further comprises: the local analysis layer uses a Shapiro-Wilk test to perform the normality analysis, when it is confirmed in the normality analysis that the deflection data and the corresponding input data of the magnetic field intensity do not have normality, performing a first data processing and then performing the normality analysis again until the data input into the local analysis layer has normality, wherein the first data processing comprises one or more of the following methods:

[0029] performing logarithmic or square root processing on the input data, and taking the processed data as new input data;

[0030] increasing the amount of data testing to obtain more input data;

[0031] performing normal distribution retesting on the input data using a frequency histogram, and if the frequency histogram shows that the input data satisfies the normal distribution, considering that the input data is normally distributed.

[0032] According to some preferred embodiments of the present application, the construction method further comprises: in the determination of normality, significance and explainability of the initial control equation by the global analysis layer, if it is determined that the initial control equation does not have any of normality, significance or explainability, then a second data processing is performed before the determination of normality, significance and explainability is performed again until the initial control equation input into the global analysis layer has normality, significance and explainability, wherein the second data processing comprises: increasing the sample amount of the deflection data, expanding the data amount of the deflection data, and establishing the initial control equation again according to the expanded deflection data.

[0033] According to some preferred embodiments of the present application, the construction method further comprises: in the determination of universality of the basic control equation by the feedback analysis layer, if it is determined that the basic control equation does not meet the universality requirement, then a third data processing is performed before the determination of universality is performed again until the obtained basic control equation meets the universality requirement, wherein the third data processing comprises:

[0034] determining whether the basic control equation does not meet the universality requirement as a whole or does not meet the universality requirement locally; wherein the basic control equation does not meet the universality requirement as a whole means that the estimated data obtained by the basic control equation does not match all data groups in the verification data set, and the basic control equation does not meet the universality requirement locally means that the estimated data obtained by the basic control equation does not match part of the data groups in the verification data set;

[0035] dividing the verification data set into a low-field intensity data set, a medium-field intensity data set and a high-field intensity data set according to the driving field intensity, specifically, defining the intensity range of the uniform magnetic field generated by the x coil or the y coil under 2-8 A current and the intensity range of the uniform magnetic field generated by the z coil under 0.2-0.8 A current as low-field intensity, and the deflection data obtained under low-field intensity constitutes the low-field intensity data set; defining the intensity range of the uniform magnetic field generated by the x coil or the y coil under 10-16 A current and the intensity range of the uniform magnetic field generated by the z coil under 1.0-1.6 A current as medium-field intensity, and the deflection data obtained under medium-field intensity constitutes the medium-field intensity data set; defining the intensity range of the uniform magnetic field generated by the x coil or the y coil under 18-22 A current and the intensity range of the uniform magnetic field generated by the z coil under 1.8-2.2 A current as high-field intensity, and the deflection data obtained under high-field intensity constitutes the medium-field intensity data set;

[0036] When the basic control equation does not satisfy the universality requirement as a whole, the basic control equation is subjected to RMSE error analysis with the low-field data set, the medium-field data set and the high-field data set respectively, if the RMSE of the smallest one of the data sets is within the range of [0, 3], it is considered that the basic control equation still satisfies the universality requirement, if the RMSE of the smallest one of the data sets is not within the range of [0, 3], the sample quantity of the deflection data is increased, the data quantity of the deflection data is expanded, and the initial control equation and the basic control equation are established again according to the expanded deflection data;

[0037] When the basic control equation does not satisfy the universality requirement locally, it is further determined whether the case that the basic control equation does not satisfy the universality requirement corresponds to the low-field data set, the medium-field data set or the high-field data set, and then the data set that does not satisfy the universality requirement is subjected to data expansion, that is, the sample quantity of the deflection data obtained under the corresponding field strength is increased, the data quantity thereof is expanded, and the initial control equation and the basic control equation are established again according to the expanded deflection data.

[0038] The present application can analyze and decode the deflection angle and deflection displacement of the magnetic guide wire under the uniform magnetic field through the data analysis model with the multi-layer analysis framework, obtain the correlation and causality between the deformation degree of the head end of the magnetic guide wire and the magnetic field strength, and then obtain the deflection control equation model with accuracy, interpretability, normality and universality, and the accurate control of the magnetic navigation surgical robot on the magnetic guide wire can be realized according to the obtained deflection control equation. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 It is the construction framework of the control model in the specific embodiment.

[0040] Figure 2 It is the working flow diagram of the magnetic guide wire manipulation system based on the Helmholtz coil in the specific embodiment.

[0041] Figure 3 It is the schematic diagram of the three-dimensional structure of the Helmholtz coil used in the specific embodiment.

[0042] Figure 4 It is the deflection mode schematic diagram (top view) of the deflection of the magnetic guide wire in the x plane of the coil in the specific embodiment, wherein B x represents the uniform magnetic field in the x direction.

[0043] Figure 5 It is the deflection mode schematic diagram (top view) of the deflection of the magnetic guide wire in the y plane of the coil in the specific embodiment, wherein B y represents the uniform magnetic field in the y direction.

[0044] Figure 6A schematic diagram (front view) of a deflection mode for generating deflection of the magnetic guide wire in the z-plane of the coil in the specific embodiment, wherein B z represents a uniform magnetic field in the z direction.

[0045] Figure 7 A schematic diagram of a deflection displacement measurement mode for the magnetic guide wire in the specific embodiment. DETAILED DESCRIPTION

[0046] The technical solutions of the present application will be described clearly and completely in combination with the specific embodiments and the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0047] Referring to the accompanying Figure 1 , the control model is constructed by the following steps:

[0048] Step 1: Prepare a hollow rectangular acrylic container with an outer length of 12.4 cm, an outer width of 8.45 cm, an outer height of 5.37 cm, an inner length of 12.1 cm, an inner width of 8.16 cm, and an inner height of 4.97 cm; prepare a magnetic guide wire control system based on a Helmholtz coil; prepare a magnetic guide wire; prepare a bionic blood, which is a mixed solution of water and glycerol in a volume ratio of 6:4.

[0049] Among them, referring to the accompanying Figure 2 , the magnetic guide wire control system based on the Helmholtz coil includes a computer, a signal generator, a power amplifier, a Helmholtz coil, a magnetic guide wire and a camera connected in sequence, wherein the computer is used to design and set the current size, direction and waveform, and can send the designed or set current parameters to the signal generator; the signal generator further inputs the received current parameters to the power amplifier, amplifies the current signal from the signal generator through the power amplifier, and inputs it to the Helmholtz coil; the used Helmholtz coil is composed of three pairs of orthogonal coils, as shown in Figure 3 , that is, x-coil, y-coil and z-coil, which can receive the current signal from the power amplifier and correspondingly generate x-plane uniform magnetic field, y-plane uniform magnetic field and z-plane uniform magnetic field to induce the deflection of the magnetic guide wire; the used magnetic guide wire is composed of neodymium iron boron magnetic powder and polydimethylsiloxane, which is a black opaque cylindrical elastomer, and can perform quantitative and directional deflection motion under the control of the uniform magnetic field generated by the Helmholtz coil; the camera is used to collect the motion image of the magnetic guide wire and transmit it back to the computer, which provides real-time visual feedback of the motion of the magnetic guide wire through the computer.

[0050] Step two: first, place the acrylic container in the working center of the Helmholtz coil. Then, fix one end of the magnetic guide wire at the center of the bottom of the acrylic container, and then fill the acrylic container with the biomimetic blood until the acrylic container is filled with the biomimetic blood. Establish a coordinate system with the center point of the uniform magnetic field generated by the Helmholtz coil as the origin, the direction of the magnetic field generated by the x-coil as the x-axis, the direction of the magnetic field generated by the y-coil as the y-axis, and the direction of the magnetic field generated by the z-coil as the z-axis. After the experimental setup is completed, the magnetic guide wire is placed at the center of the bottom of the acrylic container, and the acrylic container is placed at the center point of the Helmholtz coil, so at this time the center coordinates of the magnetic guide wire, the acrylic container and the Helmholtz coil are consistent. Then, through the magnetic guide wire control system, the x-coil, y-coil and z-coil of the Helmholtz coil are respectively applied with working current with waveform function C = ±P*|sin(t)|, wherein C is the working current, P is the current amplitude, and t is the time. By changing the current amplitude, the Helmholtz coil generates uniform magnetic fields of different sizes and directions in the x-plane, y-plane or z-plane, and the magnetic guide wire deflects in the x-plane, y-plane or z-plane, generating a plurality of deflection data.

[0051] Wherein, the working current with waveform function C = -P*|sin(t)| can drive the coil to generate a magnetic field that deflects the magnetic guide wire counterclockwise, and the working current with waveform function C = P*|sin(t)| can drive the coil to generate a magnetic field that deflects the magnetic guide wire clockwise. Therefore, by controlling the current waveform function, the magnetic guide wire can be deflected counterclockwise in the x-plane (X-plane counterclockwise deflection, XCD), clockwise in the x-plane (X-plane clockwise deflection, XWD), counterclockwise in the y-plane (Y-plane counterclockwise deflection, YCD), clockwise in the y-plane (Y-plane clockwise deflection, YWD), counterclockwise in the z-plane (Z-plane counterclockwise deflection, ZCD), and clockwise in the z-plane (Z-plane clockwise deflection, ZWD).

[0052] As in one embodiment, the working current amplitude P of the x-coil is varied from 2A to 22A at intervals of 2A, the working current amplitude P of the y-coil is varied from 2A to 22A at intervals of 2A, and the working current amplitude P of the z-coil is varied from 0.2A to 2.2A at intervals of 0.2A, so that the x-coil, y-coil and z-coil generate uniform magnetic fields of increasing intensity, respectively, to drive the magnetic guide wire placed at the center point (i.e. the origin) of the uniform magnetic field to deflect in the x-plane, y-plane and z-plane of the coil, as shown in the attached Figures 4-6 Figure 4 5 is a top view, Figure 6 is a front view, wherein B x represents the uniform magnetic field in the x-direction, B y represents the uniform magnetic field in the y-direction, and B z represents the uniform magnetic field in the z-direction), and the deflection angle is the included angle between the tangent of the deflection segment of the magnetic guide wire where deflection occurs and the tangent of the non-deflection segment where no deflection occurs, and the deflection displacement is the vertical distance between the end of the deflection segment and the non-deflection segment, as shown in the attached Figure 7 The deflection angles and deflection displacements of the magnetic guide wire in different planes are recorded.

[0053] The test results are shown in Tables 1-6 below (the unit of magnetic field intensity is milli-Tesla; the unit of deflection angle is degree; and the unit of deflection displacement is millimeter):

[0054] Table 1: Counterclockwise deflection angles of the magnetic guide wire in the x-plane under different magnetic field intensities

[0055]

[0056] Table 2: Clockwise deflection angles of the magnetic guide wire in the x-plane under different magnetic field intensities

[0057]

[0058] Table 3: Counterclockwise deflection angles of the magnetic guide wire in the y-plane under different magnetic field intensities

[0059]

[0060] Table 4: Clockwise deflection angles of the magnetic guide wire in the y-plane under different magnetic field intensities

[0061]

[0062] Table 5: Counterclockwise deflection displacements of the magnetic guide wire in the z-plane under different magnetic field intensities

[0063]

[0064] ​​Table 6 clockwise deflection displacement of magnetic guidewire in different magnetic field strength in z plane

[0065]

[0066] Step three: the clockwise and counterclockwise deflection angle, deflection displacement and corresponding magnetic field strength of the magnetic guidewire collected in different planes are taken as the input of the local analysis layer in the data analysis model, the normal analysis of the deflection angle, deflection displacement and magnetic field strength is carried out through the local analysis layer, and after confirming that they are all normally distributed, the regression equation of the clockwise and counterclockwise deflection angle, deflection displacement and magnetic field strength in different planes is established as the initial control equation of the magnetic guidewire; if the data does not have normality, the first data processing is carried out and then the normal analysis is carried out until the data used has normality.

[0067] Preferably, the local analysis layer is used to realize Shapiro-Wilk test (SWT) and linear regression (LR).

[0068] Among them, the Shapiro-Wilk test is used to analyze the normality of the field strength of the driving magnetic field, the deflection angle and the deflection displacement generated by the magnetic guidewire, and the linear regression is used to fit the measurement data and initially construct the control equation of the magnetic guidewire.

[0069] More specifically, SWT uses the following calculation model:

[0070]

[0071] Among them, q(i) represents the minimum value of sample i at time point, represents the sample mean, v i represents the coefficient matrix formed by the following matrix (V1, …, V n ).

[0072]

[0073] Among them, ω represents a vector, L represents the covariance matrix of the positive order statistics, and n represents the sample serial number.

[0074] Linear regression uses the following calculation model:

[0075] y = xβ + κ (3)

[0076] Among them, y and x can be represented as:

[0077]

[0078] Where y represents the dependent variable vector (such as the deflection angle or displacement vector), x represents the independent variable vector (such as the applied field strength vector); β and κ represent the slope and intercept, respectively, and are calculated as follows:

[0079]

[0080] In one specific embodiment, the plurality of sets of data generated in step two are input into the SWT model, and the normality of the field strength, deflection angle or displacement in each set of data is analyzed, respectively, and the results are shown in Table 7 below, wherein the normality of the field strength is represented by P B , the normality of the deflection angle or displacement is represented by P deflection , and the normality of the residual (error between the actual data and the linear regression result) is represented by P residual It can be seen that all P B and P deflection are greater than 0.05, indicating that the deflection angle or displacement of the magnetic guide wire under the action of the external uniform driving field follows a normal distribution, and the corresponding field strength also follows a standard normal distribution.

[0081] Table 7 Normality, explainability and significance analysis results of data in different motion planes

[0082]

[0083] Thereafter, each data is input into the LR model, and Φ XCD , Φ XWD , Φ YCD , Φ YWD represent the counterclockwise deflection angle in the x plane, the clockwise deflection angle in the x plane, the counterclockwise deflection angle in the y plane, and the clockwise deflection angle in the y plane, respectively, and Ψ ZCD , Ψ ZWD represent the counterclockwise deflection displacement in the z plane and the clockwise deflection displacement in the z plane, respectively, and B x , B y , B z represent the magnetic field strength applied by the Helmholtz coil in the x plane, the y plane and the z plane, respectively, and the control equation with explicit relationship is established as follows:

[0084] Under the control of the uniform magnetic field, the control equation for the magnetic guide wire with a head end composed of magnetic powder to deflect counterclockwise in the x plane is:

[0085] φ XCD = 1.26B x + 0.25

[0086] Under the control of the uniform magnetic field, the control equation for the magnetic guide wire with a head end composed of magnetic powder to deflect clockwise in the x plane is:

[0087] Φ XWD= 3.19B x -0.22

[0088] Under the control of uniform magnetic field, the control equation of the magnetic guide wire with the head end composed of magnetic powder deflecting counterclockwise in the y plane is:

[0089] Φ YCD = 1.55B y + 0.27

[0090] Under the control of uniform magnetic field, the control equation of the magnetic guide wire with the head end composed of magnetic powder deflecting clockwise in the y plane is:

[0091] Φ YWD = 2.66B y - 0.15

[0092] Under the control of uniform magnetic field, the control equation of the magnetic guide wire with the head end composed of magnetic powder deflecting counterclockwise in the z plane is:

[0093] Ψ ZCD = 1.25B z + 0.19

[0094] Under the control of uniform magnetic field, the control equation of the magnetic guide wire with the head end composed of magnetic powder deflecting clockwise in the z plane is:

[0095] Ψ ZWD = 2.35B z + 0.14.

[0096] Further, the first data processing of step three can include one or more of the following ways:

[0097] Taking the logarithm or square root of the input data to reduce the absolute size gap of the data value and maintain its relative size;

[0098] Further increasing the data amount of the input data, i.e. increasing the sample size;

[0099] Using frequency histogram for normal distribution retest, if the frequency histogram shows that the input data meets the normal distribution, it is confirmed that the input data is normally distributed.

[0100] Step four: the initial control equation output by the local analysis layer is taken as the input of the global analysis layer, and the normality, significance and explainability of the initial control equation are determined by the global analysis layer. When the initial control equation has normality, significance and explainability, the initial control equation is used as the basic control equation of the guide wire. If the data does not have any of the normality, significance or explainability, the deflection angle and displacement data of the magnetic guide wire are further collected to expand the data set, and then step three is performed again to establish new regression equations of the deflection angle, deflection displacement and magnetic field strength in different planes in clockwise and counterclockwise directions until the new regression equation meets the normality, significance and explainability.

[0101] Preferably, the global analysis layer is used to implement the Shapiro-Wilk test, F test (FT) and T test (TT) to analyze the normality, significance and explainability of the initial control equation.

[0102] More specifically, the FT uses the following calculation model:

[0103]

[0104] Wherein, SSR represents the regression sum of squares of the sample data, SSE is the error sum of squares, o is the degree of freedom, and n represents the sample number, which is the same as formula (2).

[0105] The TT uses the following calculation model:

[0106]

[0107] Wherein, x and β have the same meaning as in formula (4) and (5), x T is the transpose of x, and β is the unbiased estimate of β.

[0108] In one specific embodiment, the global analysis layer of the present application uses the SWT, FT and TT analysis algorithms to analyze the normality, significance and explainability of the initial control equation obtained by the local analysis layer. The results are shown in the hypothesis test results of Table 7. It can be seen that the residual between the actual data and the expected data in the six deflection modes of the magnetic guide wire in three planes obeys the normal distribution (P>0.05), which confirms that the normality of the initial control equation is effective. The F statistics of each deflection mode obtains a higher value, indicating that the initial control equation has a higher significance level (P<0.001) in each deflection mode. The result of using TT to evaluate the explainability of the independent variable (i.e. field strength) to the dependent variable (i.e. deflection angle or displacement) in each control equation also shows that all the initial control equations have a high explainability level (P<0.001).

[0109] Step five: taking the basic control equation output by the global analysis layer as the input of the feedback analysis layer, repeating the process of step two for 2-3 times to obtain a plurality of new deflection data as a verification data set, determining the universality of the basic control equation based on the verification data set, and using the basic control equation as the final deflection control model of the guide wire after it meets the universality requirement, wherein the universality is represented by the error value of the equation; if the basic control equation does not meet the universality requirement, the universality is determined again after the third data processing until the basic control equation meets the universality requirement.

[0110] Preferably, the root mean square error (RMSE) is used as the judgment index of the universality of the equation, and when the RMSE is in the range of [0, 3], it is considered that the basic control equation meets the universality requirement. Correspondingly, the feedback analysis layer is used to realize the RMSE calculation, and the universality of the basic control equation can be verified by using experimental data.

[0111] More specifically, the RMSE uses the following calculation model:

[0112]

[0113] Wherein, Z i represents the actual deflection angle or deflection displacement of the guide wire, K i represents the reference deflection angle or deflection displacement calculated by the control equation, and N represents the sample number.

[0114] In a specific embodiment, the process of step two is repeated twice, which are the first repeated test and the second repeated test, to obtain two parts of verification data, and the average RMSE of the basic control equation based on the two parts of verification data is shown in Table 8.

[0115] Table 8 Average RMSE and standard deviation of magnetic guide wire deflection in horizontal and vertical directions

[0116]

[0117] It can be seen that the universality of the basic control equation in this embodiment is good, which shows that the equation fitting under each deflection mode is reasonable and can be used as the final deflection control equation.

[0118] Further, the third data processing includes:

[0119] Firstly, it is judged whether the basic control equation as a whole does not meet the universality requirement or locally does not meet the universality requirement; wherein, the basic control equation as a whole does not meet the universality requirement, that is, the estimated data obtained by the basic control equation does not match all data sets in the verification data set, and the basic control equation locally does not meet the universality requirement, that is, the estimated data obtained by the basic control equation does not match part of the data sets in the verification data set;

[0120] When the basic control equation as a whole does not meet the universality requirement, the verification data set is divided into a low-field intensity data set, a medium-field intensity data set and a high-field intensity data set according to the driving field intensity. For the x coil and the y coil, the uniform magnetic field intensity range generated under the currents of 2A, 4A, 6A and 8A is defined as a low-field intensity stage, and the deflection angle range generated under the magnetic field is defined as a low-field intensity data set; the uniform magnetic field intensity range generated under the currents of 10A, 12A, 14A and 16A is defined as a medium-field intensity stage, and the deflection angle range generated under the magnetic field is defined as a medium-field intensity data set; the uniform magnetic field intensity range generated under the currents of 18A, 20A and 22A is defined as a high-field intensity stage, and the deflection angle range generated under the magnetic field is defined as a high-field intensity data set. For the z coil, the uniform magnetic field intensity range generated under the currents of 0.2A, 0.4A, 0.6A and 0.8A is defined as a low-field intensity stage, and the deflection displacement range generated under the magnetic field is defined as a low-field intensity data set; the uniform magnetic field intensity range generated under the currents of 1.0A, 1.2A, 1.4A and 1.6A is defined as a medium-field intensity stage, and the deflection displacement range generated under the magnetic field is defined as a medium-field intensity data set; the uniform magnetic field intensity range generated under the currents of 1.8A, 2.0A and 2.2A is defined as a high-field intensity stage, and the deflection displacement range generated under the magnetic field is defined as a high-field intensity data set. Then, the basic control equation is input into the feedback analysis layer again, the estimated data of the basic control equation is analyzed with different local data sets (i.e. the low-field intensity data set, the medium-field intensity data set and the high-field intensity data set) for RMSE error analysis, and the local data set with the minimum RMSE is selected as the verification data set to prove that the basic control equation meets the universality of the local data set. If the basic control equation still does not meet the universality of the local data set at this time, the deflection angle and deflection displacement data of the magnetic guide wire need to be further collected to expand the data set, and then steps three and five are re-performed until the new regression equation meets the universality requirement.

[0121] When the basic control equation does not satisfy the universality requirement locally, it indicates that the basic control equation is not applicable to part of the cases, if the part of the cases belongs to the low field intensity stage, it is necessary to further collect the deflection angle and deflection displacement data of the magnetic guide wire in the low field intensity stage, expand the low field intensity data set, and then re-perform step three to establish a new regression equation of the deflection angle, deflection displacement and magnetic field intensity in different planes in clockwise and counterclockwise directions until the new regression equation satisfies the universality requirement of the low field intensity stage. Similarly, if the basic control equation does not satisfy the universality requirement of the part of the data set in the medium field intensity stage, it is necessary to expand the medium field intensity data set, and then re-perform step three to establish a new regression equation of the deflection angle, deflection displacement and magnetic field intensity in different planes in clockwise and counterclockwise directions until the new regression equation satisfies the universality requirement of the medium field intensity stage. If the basic control equation does not satisfy the universality requirement of the part of the data set in the high field intensity stage, it is necessary to expand the high field intensity data set, and then re-perform step three to establish a new regression equation of the deflection angle, deflection displacement and magnetic field intensity in different planes in clockwise and counterclockwise directions until the new regression equation satisfies the universality requirement of the high field intensity stage. In the RMSE calculation process, the actual deflection angle or deflection displacement data set of the magnetic guide wire and the reference deflection angle or deflection displacement data set calculated by the basic control equation are calculated according to formula (8), and the steps of subtraction, opening, continuous addition, division and square root are sequentially performed, and finally the error between the actual deflection data of the magnetic guide wire and the reference deflection data calculated by the basic control equation is obtained. When the RMSE is in the range of [0, 3], it is confirmed that the basic control equation still satisfies the universality requirement.

[0122] The above embodiment is a preferred embodiment of the present application, and the protection scope of the present application is not limited to the above embodiment. Any technical solution falling within the concept of the present application belongs to the protection scope of the present application. It should be pointed out that, for ordinary skilled in the art, the improvements and decorations without departing from the principles of the present application should also be considered as the protection scope of the present application.

Claims

1. A device for constructing a magnetic guidewire deflection control model, comprising: A magnetic guidewire steering system, comprising: a computer, a signal generator connected to the computer, a power amplifier connected to the signal generator and a Helmholtz coil, and a photographing device connected to the computer and capable of collecting images of deflection of the magnetic guidewire.

2. The build apparatus of claim 1, wherein, 3. The method for constructing a magnetic guidewire deflection control model of a construction device according to claim 1 or 2, comprising: obtaining a plurality of sets of deflection data of the magnetic guidewire in an x plane corresponding to the x coil, a y plane corresponding to the y coil, and a z plane corresponding to the z coil of the Helmholtz coil under a uniform magnetic field generated by the Helmholtz coil by providing varying currents to the x coil, the y coil, and the z coil of the Helmholtz coil respectively by the magnetic guidewire steering system, wherein the deflection data comprises clockwise and counterclockwise deflection angles and deflection displacements of the magnetic guidewire; inputting the collected deflection data and corresponding magnetic field intensity into a local analysis layer of a data analysis model, performing normal analysis of the deflection angles, the deflection displacements, and the magnetic field intensity by the local analysis layer, and establishing linear regression equations of the clockwise and counterclockwise deflection angles, the deflection displacements, and the magnetic field intensity in the x plane, the y plane, and the z plane as initial control equations of the magnetic guidewire after confirming that the deflection angles, the deflection displacements, and the magnetic field intensity are normally distributed; inputting the initial control equations output by the local analysis layer into a global analysis layer of the data analysis model as input, determining normality, significance, and interpretability of the initial control equations by the global analysis layer, and using the initial control equations as basic control equations of the magnetic guidewire after the initial control equations possess the normality, the significance, and the interpretability; repeating the process of obtaining the deflection data several times to obtain new sets of deflection data as validation data in a validation data set, and then inputting the basic control equations output by the global analysis layer and the validation data set into a feedback analysis layer of the data analysis model as input, determining the universality of the basic control equations with respect to the validation data by the feedback analysis layer, and using the basic control equations as a final deflection control model of the magnetic guidewire after the basic control equations meet the universality requirement. wherein, 4. The construction method according to claim 3, characterized in that, the normal analysis by the local analysis layer uses Shapiro-Wilk test; and / or the normality determination by the global analysis layer is realized using Shapiro-Wilk test; and / or the significance determination by the global analysis layer is realized using F test; and / or the interpretability determination by the global analysis layer is realized using T test, and / or the universality is realized by root mean square error. ​ 5. The construction method of claim 3, wherein, The changing current is generated by the following current model: C=±P*|sin(t)|, where C represents the operating current, P represents the current amplitude, t represents time, + represents the clockwise direction, and - represents the counterclockwise direction.

6. The construction method of claim 5, wherein, The acquisition of the multiple sets of deflection data includes: under a current amplitude that varies discretely according to a gradient, the magnetic guide wire manipulation system provides current to the x coil, y coil, and z coil respectively according to the current model, and records the deflection angle and deflection displacement generated by the magnetic guide wire under each current amplitude to obtain the multiple sets of deflection data.

7. The construction method of claim 3, wherein, It also includes: the local analysis layer uses the Shapiro-Wilke test to perform the normality analysis; if the normality analysis confirms that the deflection data and its corresponding magnetic field strength, i.e., the input data, do not have normality, then a first data processing is performed before performing the normality analysis again, until the data input to the local analysis layer has normality, wherein the first data processing includes one or more of the following methods: The input data is processed by taking the logarithm or square root, and the processed data is used as the new input data. Increase the amount of data tested to obtain more input data; The input data is re-tested for normality using a frequency histogram. If the frequency histogram shows that the input data follows a normal distribution, then the input data is considered to be normally distributed.

8. The construction method of claim 3, wherein, It also includes: in the determination of the normality, significance, and interpretability of the initial control equation by the global analysis layer, if it is determined that the initial control equation does not possess any of the properties of normality, significance, or interpretability, then a second data processing is performed before determining normality, significance, and interpretability again, until the initial control equation input to the global analysis layer possesses normality, significance, and interpretability. The second data processing includes: increasing the sample size of the obtained deflection data, expanding the data volume of the deflection data, and re-establishing the initial control equation based on the expanded deflection data.

9. The construction method of claim 3, wherein, It also includes: the feedback analysis layer uses the root mean square error (RMSE) to characterize the universality, and when the RMSE is in the range of [0,3], the basic control equation is considered to meet the universality requirement.

10. The construction method of claim 9, wherein, In determining the universality of the basic control equations by the feedback analysis layer, if it is determined that the basic control equations do not meet the universality requirement, then a third data processing step is performed before determining universality again, until the obtained basic control equations meet the universality requirement. The third data processing includes: Determine whether the basic control equation fails to meet the universality requirement as a whole or only partially; wherein, if the basic control equation fails to meet the universality requirement as a whole, it means that the estimated data obtained from the basic control equation does not match all data groups in the validation dataset, and if the basic control equation fails to meet the universality requirement only partially, it means that the estimated data obtained from the basic control equation does not match some data groups in the validation dataset. The verification dataset is divided into low-field-strength, medium-field-strength, and high-field-strength datasets based on the magnitude of the driving field intensity. Specifically, the intensity range of the uniform magnetic field generated by the x-coil or y-coil under a current of 2–8A and the intensity range of the uniform magnetic field generated by the z-coil under a current of 0.2–0.8A are defined as low-field-strength datasets, and the deflection data obtained under low-field-strength datasets constitute the low-field-strength datasets. The intensity range of the uniform magnetic field generated by the x-coil or y-coil under a current of 10–16A and the intensity range of the uniform magnetic field generated by the z-coil under a current of 1.0–1.6A are defined as medium-field-strength datasets, and the deflection data obtained under medium-field-strength datasets constitute the medium-field-strength datasets. The intensity range of the uniform magnetic field generated by the x-coil or y-coil under a current of 18–22A and the intensity range of the uniform magnetic field generated by the z-coil under a current of 1.8–2.2A are defined as high-field-strength datasets, and the deflection data obtained under high-field-strength datasets constitute the medium-field-strength datasets. When the basic control equation does not meet the universality requirement as a whole, RMSE error analysis is performed on the basic control equation with the low field strength dataset, the medium field strength dataset and the high field strength dataset respectively. If the dataset with the smallest RMSE satisfies the RMSE within the range of [0,3], then the basic control equation is considered to still meet the universality requirement. If the dataset with the smallest RMSE does not satisfy the RMSE within the range of [0,3], then the sample size of the deflection data is increased, the amount of the deflection data is expanded, and the initial control equation and the basic control equation are re-established based on the expanded deflection data. When the basic control equation does not meet the universality requirement locally, it is further determined whether the case of not meeting the universality requirement corresponds to a low field strength dataset, a medium field strength dataset, or a high field strength dataset. Then, the dataset that does not meet the universality requirement is expanded, that is, the sample size of the deflection data obtained under the corresponding field strength is increased to expand its data volume. Based on the expanded deflection data, the initial control equation and the basic control equation are re-established.

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