Disclosure of Invention
The invention solves the problems of extremely complex calibration and extremely high equipment of strain gauge sensors in the prior art, and provides a catheter calibration method and device based on grid partition.
In order to achieve the above object, the present invention provides the following technical solutions:
a grid partition-based catheter calibration method for a catheter with a plurality of pressure sensors at a stress end, comprising the following steps:
s1, establishing a parameter matrix at a catheter stress end according to a preset azimuth angle, an elevation angle and an acting force; vectorizing the parameter matrix, and establishing a basic parameter vector matrix;
s2, applying acting force to the stress end of the catheter according to the parameter matrix, collecting the pressure value of the pressure sensor, and constructing a basic pressure matrix, wherein an array in the basic pressure matrix and a vector in the basic parameter vector matrix are in one-to-one correspondence;
and S3, establishing a pressure value calibration relation model according to the basic pressure matrix and the basic parameter vector matrix, wherein the pressure value calibration relation model is used for solving the stress magnitude and the stress direction of the catheter according to the value of the pressure sensor acquired in real time.
As a preferred scheme of the invention, the parameter matrix establishment process of the step S1 is as follows: the center of the cross section of the catheter is taken as the origin of spherical coordinates, the cross section of the catheter is equally divided into N azimuth angles, the angle from the axis of the catheter to the cross section of the catheter is equally divided into K elevation angles, and the acting force in the direction of the axis of the catheter is a scalar distance.
As a preferable scheme of the invention, the value of N is 12, and the value of azimuth angle is: 0 °,30 °,60 °,90 °,120 °,150 °,180 °,210 °,240 °,270 °,300 °,330 °,360 °.
As a preferable scheme of the invention, the value of K is 4, and the value of the elevation angle is: 0 °,30 °,60 °,90 °.
As a preferable mode of the invention, the acting force in the axial direction of the catheter takes the values of 10g,20g,30g,40g,50g,60g and 70g.
In a preferred embodiment of the present invention, in step S1, the vector in the base parameter vector matrix is represented by a first parameter δi Second parameter epsiloni And a third parameter mui The composition of the composite material comprises the components,
first parameter deltai The calculation formula of (2) is as follows:
second parameter epsiloni The calculation formula of (2) is as follows:
third parameter mui The calculation formula of (2) is as follows:
wherein alpha isi Is the elevation angle, betai The azimuth angle is F, the acting force is 1.ltoreq.i.ltoreq.n, and n is the total number of arrays formed according to the azimuth angle, the elevation angle and the acting force in the parameter matrix.
As a preferred embodiment of the present invention, the pressure value calibration relation model is:
Mi ＝pinv(Qi )*Ri
wherein M isi Cell relation matrix of pressure value calibration relation model, Ri Is a basic parameter vector matrix, Qi The matrix is a basic pressure matrix, an array in the basic pressure matrix is a pressure value array corresponding to a vector in a basic parameter vector matrix, pinv () is an inversion formula, i is more than or equal to 1 and less than or equal to n, and n is the total number of vectors in the basic parameter vector matrix.
Based on the same conception, the invention also provides a method for detecting the stress of the catheter, which is used for the catheter with a plurality of pressure sensors distributed at the stress end, and comprises the following steps:
a1, simultaneously acquiring pressure values of a plurality of pressure sensors to form a pressure acquisition array;
a2, a pressure value calibration relation model obtained by adopting any one of the calibration methods is adopted, and a reference cell relation matrix with the shortest relative distance with the pressure acquisition array is found from the pressure value calibration relation model;
a3, according to the reference cell relation matrix and the pressure acquisition array, the stress magnitude and the stress direction of the catheter are calculated.
As a preferred embodiment of the present invention, the step A2 specifically includes the steps of:
a21, solving the relative distance between the current pressure acquisition array and the array in the basic pressure matrix;
a22, finding the index number of the corresponding array when the relative distance is minimum;
a23, finding out a corresponding reference cell relation matrix in the pressure value calibration relation model according to the index number.
Based on the same conception, the invention also provides a catheter calibration device based on grid partition, which comprises a force application device, a force application size measuring device and an azimuth angle and elevation angle control device for controlling the force application direction, wherein the force application device is used for applying pressure to the stress end of the catheter,
the force application measuring device is used for collecting the pressure value applied to the stress end of the guide tube in real time,
the azimuth angle and elevation angle control device for controlling the force application direction is used for controlling the force application device to apply pressure to the force receiving end of the catheter according to the preset azimuth angle and elevation angle,
the force application device, the force application magnitude measuring device and the azimuth angle and elevation angle control device for controlling the force application direction apply force to the force receiving end of the catheter according to any one of the calibration methods.
Compared with the prior art, the invention has the beneficial effects that:
the invention discloses a pressure calibration method and a pressure calibration device for a pressure sensing electrophysiological catheter.
Detailed Description
The present invention will be described in further detail with reference to test examples and specific embodiments. It should not be construed that the scope of the above subject matter of the present invention is limited to the following embodiments, and all techniques realized based on the present invention are within the scope of the present invention.
The pressure sensing catheter, as shown in fig. 1, can be divided into three parts, distal, proximal, and handle, wherein the distal end contains a pressure sensor. The arrangement of the pressure sensors at the distal end of the catheter has various forms, an example of arranging three and four pressure sensors at the distal end of the pressure sensing catheter is shown in fig. 1, three pressure sensors (or four pressure sensors) are arranged along the circumferential direction of the catheter when the cross section of the catheter is seen, by the calibration method of the invention, real-time calibration output of the pressure value and the pressure direction of the catheter can be realized, and fig. 2 shows a schematic diagram of the arrangement of the electrode at the distal end of the catheter, which is used for energy output, and the stress direction and the size of the distal end of the catheter directly influence the working effect of the electrode.
Specifically, the pressure sensing catheter distal electrode is fixedly connected with an elastomer, the elastomer enables the distal electrode to return to a natural state after pressure is removed, and a plurality of pressure sensors are uniformly distributed in a stress concentration area on the elastomer. Taking 3 pressure sensors as an example, the 3 pressure sensors are symmetrically arranged on the elastic body. The value reflected by each pressure sensor when sensing stretching and compressing can be regarded as a vector with directivity (namely positive and negative), and when the pressure sensing catheter is subjected to pressure with direction, the three pressure sensors can detect the corresponding vector value with uniqueness. And measuring different numerical groups of the pressure sensors (each group is provided with positive and negative numerical values of 3 pressure sensors) when various pressures and various directions are known, and sorting the obtained corresponding relations into a database storage data storage module. The method can correct the stress magnitude and direction of the catheter according to pre-stored data in the actual measurement process, so that the calculated value is more accurate.
Example 1
A flowchart of a grid partition based catheter calibration method, as shown in fig. 3, includes the steps of:
s1, a spherical coordinate system is established at a catheter stress end according to a preset azimuth angle, an elevation angle and acting force along the axial direction of the catheter, and a parameter matrix is established.
S2, vectorizing the parameter matrix, and establishing a basic parameter vector matrix.
And S3, applying acting force to the stress end of the catheter according to the parameter matrix, and simultaneously collecting the pressure value of the pressure sensor to construct a basic pressure matrix, wherein an array in the basic pressure matrix and a vector in the basic parameter vector matrix are in one-to-one correspondence.
And S4, establishing a pressure value calibration relation model according to the basic pressure matrix and the basic parameter vector matrix, wherein the pressure value calibration relation model is used for solving the stress magnitude and the stress direction of the catheter according to the pressure sensor acquired in real time.
In step S1, a spherical coordinate system is established at the distal end of the catheter according to the preset azimuth, elevation and acting force, and a schematic diagram of the establishment of the spherical coordinate system at the distal end of the catheter according to the preset azimuth, elevation and acting force is shown in fig. 4. The direction of the axis of the catheter is taken as a Z axis, the center of the cross section of the catheter is taken as an origin of spherical coordinates, the cross section of the catheter is taken as an XOY plane, a spherical coordinate system is correspondingly established, the azimuth angle is beta, the elevation angle is alpha, the cross section of the catheter is equally divided into N azimuth angles, and the angle from the axis of the catheter to the cross section of the catheter is equally divided into K elevation angles. The force F applied to the catheter acts as a scalar distance in the spherical coordinate system.
As a preferred scheme, the cross section of the catheter is equally divided into 12 azimuth angles, n=12, the azimuth angle takes the value of 0 °,30 °,60 °,90 °,120 °,150 °,180 °,210 °,240 °,270 °,300 °,330 °,360 °, and the azimuth angle subareas are seen in the top view direction as shown in fig. 5. The azimuth angle may be equally divided by other values, such as n=6, n=24, n=36, etc., as desired.
As a preferred solution, the angle from the catheter axis to the catheter cross section is equally divided into 4 elevation angles, k=4, the azimuth angle has a value of 0 °,30 °,60 °,90 °, and the elevation angle is divided as shown in fig. 6 when looking in the lateral direction. The azimuth angle may be equally divided by other values, such as n=3, n= 5,N =6, etc., as desired.
As a preferred embodiment, the applied force F to the guide tube has values of 10g,20g,30g,40g,50g,60g,70g, where g is the unit gram, which is the unit of reading of the load cell, 1g corresponds to the weight of 1g of the object, and if g takes 9.8N/Kg, 1g is the unit of reading, which means 9.8X10-3 N。
For a clearer explanation scheme, the method of the invention will be described below with values of azimuth angle of 0 °,30 °,60 °,90 °,120 °,150 °,180 °,210 °,240 °,270 °,300 °,330 °,360 °, elevation angle of 0 °,30 °,60 °,90 °, and applied forces F by the catheter of 10g,20g,30g,40g,50g,60g,70g, respectively, but the invention is not limited to a scheme that can only be implemented in sequence, but is still within the scope of the invention based on the inventive concept with other values for catheter calibration and catheter pressure testing.
From the azimuth angle beta, the elevation angle alpha and the force F exerted by the catheter, a parameter matrix P can be established, wherein,n is the total number of arrays of parameters in the parameter matrix P based on azimuth, elevation and applied force. For example, the azimuth angle β is 12, the elevation angle α is 4, and the acting force F is 7, and after being arranged and combined, the force application schemes of 12×4×7=364, that is, the force application schemes of 364 arrays are formed, namely, the force application schemes of 364 arrays are formed>
In step S2, the parameter matrix is vectorized, and the calculation method is as follows:
setting the basic parameter vector matrix as R, wherein,the vectors in the basic parameter vector matrix are represented by a first parameter deltai Second parameter epsiloni And a third parameter mui The composition of the composite material comprises the components,
establishing an array in the parameter matrix and a vector in the basic parameter vector matrix through the subscript iEach parameter matrix array corresponds to the vector of the basic parameter vector matrix, so the same subscript is adopted. When (when)Correspondingly, a->
In step S3, when a plurality of pressure sensors are disposed at the stress end of the catheter, when an acting force is applied to the stress end of the catheter according to the parameter matrix, pressure values of the plurality of pressure sensors can be collected to form a plurality of sets of pressure value arrays, the plurality of pressure value arrays can form a base pressure matrix, and taking a pressure sensing catheter with three pressure sensors as an example, the obtained base pressure matrix is expressed as:when->When corresponding to(α1 ，β1 Under the force application scheme of F), the acquired basic pressure array is (x)1 ，y1 ，z1 )，(α2 ，β2 ，F2 ) Under the force application scheme of (2), the acquired basic pressure array is (x)2 ，y2 ，z2 ) And by analogy, establishing a one-to-one correspondence between the array in the parameter matrix and the array in the basic pressure matrix through the subscript i. Therefore, by the subscript i, a one-to-one correspondence is established between the vectors in the base parameter vector matrix and the arrays in the base pressure matrix.
In step S4, a pressure value calibration relation model is established according to the basic pressure matrix and the basic parameter vector matrix, and the method specifically includes the following steps:
according to the basic parameter vector matrix Ri And a base pressure matrix Qi Can be calculatedSolving a relation matrix of the two, wherein the relation matrix has a calculation formula as follows:
Mi ＝pinv(Qi )*Ri
wherein pinv () is an inversion formula, i is 1-n, n is the total number of arrays formed by the parameter matrix P according to azimuth angle, elevation angle and acting force, and is the number of vectors in the basic parameter vector matrix, and is the number of arrays in the basic pressure matrix. M is Mi And (5) calibrating the relation model by the established pressure value. Taking a catheter with three pressure sensors at its end as an example, a matrix of base pressuresCorrespondingly, Mi Is a3 x 3 matrix.
Matrix of relations Mi With base pressure sub-matrix Qi Write memory module, denoted as cell= { Mi ，Qi And the output procedure call is supplied and used for solving the stress size and the stress direction of the catheter according to the pressure sensor acquired in real time, wherein i is more than or equal to 1 and less than or equal to n, and n is the total number of the array formed according to azimuth angle, elevation angle and acting force in the parameter matrix P.
Example 2
Example 1 shows a grid partition based catheter calibration method and builds a pressure value calibration relationship model. The method requires a corresponding device to carry out. One of the calibration devices is shown in fig. 7, and includes a bracket, a force applying device movable up and down on the bracket, a force applying magnitude measuring device mounted on the force applying device, and a rocker arm angle and rotation angle control device for controlling the force applying direction.
The force application device module controls the force application device to move up and down or left and right along the support so as to realize the contact and pressure application of the force application platform and the catheter head end, and the force application size measurement device feeds back the size of the applied pressure in real time. The force application device control module realizes accurate force application to the catheter head end according to feedback.
The rocker arm angle and rotation angle control device for controlling the force application direction comprises a force application angle control module, a rocker arm angle control motor and a rotation angle control motor. The force application angle control module realizes accurate control of force application direction through the rocker arm angle control motor and the rotating angle control motor.
The catheter is fixed on the fixture of the force application angle control module, the tail end electrode and the pressure sensor part are exposed, the angle relation between the catheter head end and the force application table, namely, the rocker angle (corresponding to the azimuth angle in the spherical coordinate system) is controlled under the drive of the rocker control motor, and the rotation angle of the catheter head end and the force application table (corresponding to the elevation angle in the spherical coordinate system) is controlled by the rotation angle control motor. The force application detection module is a standard pressure electronic scale and can slide up and down and left and right on the force application device so as to meet the control of the set rocker angle and the rotation angle.
By the calibration device, the front end of the catheter can be applied with force according to the set azimuth angle, elevation angle and acting force, data are collected, and a pressure value calibration relation model is established.
Example 3
Example 3 shows another calibration device, as shown in fig. 8. The device comprises an angle adjusting device, a standard electronic scale and control equipment.
The catheter is fixed on the angle adjusting device, the tail end electrode and the pressure sensor part are exposed, the contact part of the head end of the standard electronic scale device and the catheter is a flat plane, the contact part is recorded when a force is applied to the plane, the included angle (elevation angle) between the tail end electrode of the catheter and the plane of the electronic scale and the rocker angle (azimuth angle) are controlled by the angle adjusting device on the control equipment, the rotation of the catheter, namely the rotation angle between the tail end electrode of the catheter and the plane of the electronic scale, can be controlled by the rotation control device on the control equipment, and the integral movement of the tail end electrode of the catheter can be controlled by the control equipment so as to realize the control of the set angle and pressure.
Example 4
The pressure and direction of the conduit can be obtained by calibrating the relation model according to the obtained pressure value, so a method for detecting the stress of the conduit is provided, and the flow chart is shown in figure 9. The method comprises the following steps:
a1, simultaneously acquiring pressure values of a plurality of pressure sensors to form a pressure acquisition array. Wherein the pressure isThe sensors are arranged at the far end of the catheter as shown in fig. 2, and the sensors are arranged at the far end of the catheter, the embodiment is illustrated by 3 pressure sensors, and a real-time collected pressure collection array is marked as Vin ＝(xnow ，ynow ，znow )。
A2, a pressure value calibration relation model obtained by the calibration method of the embodiment 1 is adopted, and a reference cell relation matrix with the shortest relative distance with the pressure acquisition array is found from the pressure value calibration relation model.
A3, according to the reference cell relation matrix and the pressure acquisition array, the stress magnitude and the stress direction of the catheter are calculated.
Further, step A2 includes the steps of:
a21, obtaining the relative distance between the current pressure acquisition array and the array in the basic pressure matrix.
A22, finding the index number of the corresponding array when the relative distance is minimum;
a23, finding out a corresponding cell relation matrix in the pressure value calibration relation model according to the index number, wherein the cell relation matrix corresponding to the index number is used as the reference cell relation matrix.
In step A21, L is preferably usedp Distance (L)p Distance) or Minkowski Distance (Minkowski Distance) to calculate the current pressure acquisition array Vin ＝(xnow ，ynow ，znow ) And a base pressure matrix Qi The relative distance of the array in the middle is Lp Distance (Min Shi distance) example, current pressure acquisition array Vin ＝(xnow ，ynow ，znow ) The relative distance to the ith base pressure array is calculated as follows:
wherein,is the current pressure acquisition array Vin ＝(xnow ，ynow ，znow ) The relative distance from the i-th base pressure array is 1.ltoreq.i.ltoreq.n, where n is the base pressure matrix Qi The total number of arrays, p, is a constant, and a slice may take 1 or 2.
In step A22, the relative distances are comparedFinding out the minimum value of the relative distance and the index number i corresponding to the minimum valuemin 。
In step A23, index number i corresponding to the minimum relative distancemin Finding a relationship matrix in a pressure value calibration relationship modelThe corrected conduit pressure gamma can be obtained by using the following formulaout And direction (by rocker angle alpha)out Rotation angle betaout Representation):
wherein, gammaout Is the output conduit pressure magnitude, alphaout Is the output rocker angle betaout Is the rotation angle of the output and,minimum relative distance index number imin Corresponding relation matrix, xout 、yout And zout Is via a relation matrix->Vector values of the three corrected pressure sensors.
With the above calibration device and calibration scheme, 100 groups are randomly verified, and the effect is as shown in fig. 10, the pressure deviation is the true value minus the system output pressure value, the rocker arm angle deviation is the true value minus the system output rocker arm angle value, and the rotation angle deviation is the true value minus the system output rotation angle value.
The foregoing description of the preferred embodiments of the invention is not intended to limit the invention to the particular embodiments disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.