Sensor structure for catheter guidewire push resistance measurement

Abstract

The application provides a sensor structure for catheter guide wire push resistance measurement, comprising left and right clamping nuts installed on both sides of a right and left threaded screw shaft, a piece of metal sheet elastomer is installed between the left clamping nut and the left chuck and between the right clamping nut and the right chuck respectively, a first strain gauge and a second strain gauge are attached to one side of the metal sheet elastomer in the thickness direction of the metal sheet elastomer, a third strain gauge and a fourth strain gauge are attached to the other side of the metal sheet elastomer in the thickness direction of the metal sheet elastomer, the third strain gauge coincides with the first strain gauge in the thickness direction of the metal sheet elastomer, and the fourth strain gauge coincides with the second strain gauge in the thickness direction of the metal sheet elastomer. The metal sheet elastomer is in the shape of a sheet, has strong bending resistance in the clamping direction and weak bending resistance in the catheter guide wire pushing and withdrawing direction, can inhibit the bending stress interference caused by the clamping force, and can amplify the bending stress measurement value of the pushing and withdrawing force.

Description

Technical Field

[0001] This invention relates to the field of catheter guidewire measurement device technology, and more specifically, to a sensor structure for measuring catheter guidewire pushing resistance. Background Technology

[0002] When a surgical robot pushes and retracts catheters and guidewires, it is necessary to detect the pushing and retraction forces on the catheters and guidewires. This requires placing force sensors on the robot's end effector. However, in practice, it has been found that general-purpose force sensors often fail to provide accurate and reliable readings. This is mainly because the force exerted by the robot on the catheters and guidewires is significant, affecting the measurement of the pushing force. This effect manifests in two main ways:

[0003] First, selecting the appropriate sensor range is extremely difficult. The pushing force of catheters and guidewires is often very small, usually around 1N to 2N, and even at its largest, only 5N to 10N. Therefore, a force sensor with a small range and high accuracy is preferable. However, the clamping force of catheters and guidewires is relatively large, typically 50N or even higher. Although the direction of the clamping force is perpendicular to the direction of the pushing force being measured, using a force sensor with a small range can easily lead to sensor damage.

[0004] Second, since the clamping force is much greater than the thrust, and the clamping force value is different each time, many uncertain clamping force components are coupled when measuring thrust, which are difficult to eliminate simply.

[0005] In actual measurements, when the thrust changes, the linearity between the data changes measured by the general force sensors in the existing technology and the changes in thrust is not good. These problems make it difficult to measure the pushing force and retraction force of the catheter guidewire, and there are areas for improvement. Summary of the Invention

[0006] In view of the deficiencies in the prior art, the purpose of this invention is to provide a sensor structure for measuring the resistance of catheter guidewire pushing.

[0007] According to the present invention, a sensor structure for measuring the pushing resistance of a catheter guidewire includes a left clamp, a right clamp, a screw with positive and negative threads, a left clamping nut, a right clamping nut, a thin metal sheet elastomer, a first strain gauge, a second strain gauge, a third strain gauge, and a fourth strain gauge. The left and right clamping nuts are respectively mounted on opposite sides of the axial direction of the screw with positive and negative threads, the axial direction of which is perpendicular to the forward and backward direction of the catheter guidewire. A thin metal sheet elastomer is installed between the left clamping nut and the left clamp, and between the right clamping nut and the right clamp, respectively. The thickness direction of each thin metal sheet is parallel to the forward and backward direction of the catheter guidewire. Both the first and second strain gauges are vertically attached to the thickness direction of one of the thin metal sheet elastomers. On one side of the structure, the first and second strain gauges are spaced apart in the horizontal direction and are at the same height in the vertical direction. The third and fourth strain gauges are vertically attached to the other side of the structure along the thickness direction of a metal sheet elastomer. The third strain gauge coincides with the first strain gauge in the thickness direction of the metal sheet elastomer, and the fourth strain gauge coincides with the second strain gauge in the thickness direction of the metal sheet elastomer. The first, second, third, and fourth strain gauges form a Wheatstone bridge, with the first and second strain gauges on one opposite bridge arm and the third and fourth strain gauges on another set of opposite bridge arms.

[0008] Preferably, the output voltage of the Wheatstone bridge is denoted as ΔU, the resistance of the first strain gauge is R1, the resistance of the second strain gauge is R2, the resistance of the third strain gauge is R3, the resistance of the fourth strain gauge is R4, and the resistance change of the first strain gauge (2) is... The resistance change of the second strain gauge (3) is The resistance change of the third strain gauge (4) is The resistance change of the fourth strain gauge (5) is ;

[0009]

[0010] in, The strain value of the first strain gauge. The strain value of the second strain gauge, The strain value of the third strain gauge, This is the strain value of the fourth strain gauge.

[0011] Preferably, when the left and right clamps clamp the catheter guidewire and apply an advancing or withdrawing force to the catheter guidewire; F N This represents the normal force exerted on the plane of the right clamp. F SThis represents the static friction between the guidewire and the right clamp plane; tensile strain is generated at the points where both the first and third strain gauges are located. Compressive strain is generated at the locations of both the second and fourth strain gauges. Compressive strain is generated at the points where both the first and second strain gauges are located. Tensile strain is generated at the locations of both the third and fourth strain gauges. Tensile stress is simultaneously generated at the locations of the first strain gauge, the second strain gauge, the third strain gauge, and the fourth strain gauge. .

[0012] Preferably, considering the superposition effect, , , = , .

[0013] Preferably, = .

[0014] Preferably, a left mounting post is fixedly provided on the left clamp, and a right mounting post is fixedly provided on the right clamp. The left mounting post is fixedly connected to the metal sheet elastomer by fasteners.

[0015] Preferably, a lower pad is provided between the left mounting post and the metal sheet elastomer; and an upper pad is provided between the left clamping nut and the metal sheet elastomer.

[0016] Preferably, a right mounting post is fixedly provided on the right clamp, and the right mounting post is fixedly connected to the metal sheet elastomer by fasteners.

[0017] Preferably, a lower pad is provided between the right mounting post and the metal sheet elastomer; and an upper pad is provided between the right clamping nut and the metal sheet elastomer.

[0018] Preferably, the circuit of the Wheatstone bridge includes a first strain gauge, a second strain gauge, a third strain gauge, a fourth strain gauge, a power supply, and a Wheatstone bridge output terminal; the positive terminal of the power supply is connected to one end of the first strain gauge and one end of the third strain gauge, the other end of the first strain gauge is connected to one end of the Wheatstone bridge output terminal and one end of the fourth strain gauge, the other end of the third strain gauge is connected to the other end of the Wheatstone bridge output terminal and one end of the second strain gauge, and the other end of the fourth strain gauge is connected to the other end of the second strain gauge and the negative terminal of the power supply.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. This invention designs the shape of the metal sheet elastomer as a sheet type, which has strong bending resistance in the clamping direction and weak bending resistance in the pushing and retracting direction of the guide wire. This can suppress the bending stress interference caused by the clamping force and amplify the bending stress measurement value of the pushing and retracting force.

[0021] 2. The present invention uses four strain gauges arranged vertically to form a full bridge, wherein the first strain gauge and the second strain gauge are on opposite bridge arms. This arrangement can eliminate the bending stress generated by the clamping force and amplify the bending stress caused by the pushing and withdrawing force of the guide wire.

[0022] 3. By adjusting the thickness of the upper and lower pads of the mounting force sensor, this invention can minimize the torque effect caused by clamping force. Attached Figure Description

[0023] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0024] Figure 1 This is a schematic diagram illustrating the overall installation structure of the sensor used to measure catheter guidewires, which is the main feature of this invention.

[0025] Figure 2 This is a schematic diagram illustrating the front structure of the metal sheet elastomer, which is the main feature of this invention.

[0026] Figure 3 This is a schematic diagram illustrating the side structure of the metal sheet elastomer, which is the main feature of this invention.

[0027] Figure 4 This is a schematic diagram illustrating the force applied to the chuck, which is the main feature of this invention.

[0028] Figure 5 This is a circuit diagram that mainly illustrates the overall circuit of the Wheatstone bridge in this invention.

[0029] As shown in the figure:

[0030] Detailed Implementation

[0031] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0032] It should be noted that the vertical direction in this application is the Y-axis direction in the spatial coordinate system, the thickness direction of the metal sheet elastomer 1 in this application is the Z-axis direction in the spatial coordinate system, and the axial direction of the positive and negative threaded screw 6 in this application is the X-axis direction in the spatial coordinate system.

[0033] like Figure 1 As shown, a sensor structure for measuring the pushing resistance of a catheter guidewire according to the present invention includes a left clamp 14, a right clamp 15, a screw with positive and negative threads 6, a left clamping nut 7, a right clamping nut 8, a metal sheet elastomer 1, a first strain gauge 2, a second strain gauge 3, a third strain gauge 4, and a fourth strain gauge 5.

[0034] Left clamping nut 7 and right clamping nut 8 are respectively installed on both sides of the axial direction of the positive and negative threaded screw 6. The axial direction of the positive and negative threaded screw 6 is perpendicular to the forward and backward direction of the guide wire 16. A thin metal sheet elastomer 1 is installed between the left clamping nut 7 and the left chuck 14, and between the right clamping nut 8 and the right chuck 15. The thickness direction of each thin metal sheet is parallel to the forward and backward direction of the guide wire 16. The first strain gauge 2 and the second strain gauge 3 are both vertically attached to one side of the thin metal sheet elastomer 1 along its thickness direction. The first strain gauge 2 and the second strain gauge 3 are spaced apart in the horizontal direction and are at the same height in the vertical direction. The third strain gauge 4 and the fourth strain gauge 5 are both vertically attached to the other side of the thin metal sheet elastomer 1 along its thickness direction. The third strain gauge 4 coincides with the first strain gauge 2 in the thickness direction of the thin metal sheet elastomer 1, and the fourth strain gauge 5 coincides with the second strain gauge 3 in the thickness direction of the thin metal sheet elastomer 1. Furthermore, the first strain gauge 2, the second strain gauge 3, the third strain gauge 4, and the fourth strain gauge 5 form a Wheatstone bridge. The first strain gauge 2 and the second strain gauge 3 are on one opposite bridge arm, and the third strain gauge 4 and the fourth strain gauge 5 are on another opposite bridge arm.

[0035] Specifically, the metal sheet elastomer 1 has a sheet structure and can be made of a high-strength, low-elastic-modulus metal material. The sheet is symmetrical from left to right, with uniform thickness and a flat surface, facilitating its installation. The strain gauge is installed in a vertical direction.

[0036] The left clamping nut 7 and the right clamping nut 8 are symmetrically installed on both sides of the positive and negative threaded screw 6 along the axial direction. A left mounting post 12 is fixedly mounted on the left collet 14, and a right mounting post 13 is fixedly mounted on the right collet 15. The left mounting post 12 is fixedly connected to the thin metal sheet elastomer 1 by fasteners. A lower pad 11 is provided between the left mounting post 12 and the thin metal sheet elastomer 1. Upper pads 10 are provided between the left clamping nut 7 and the thin metal sheet elastomer 1. The right clamping nut 13 is fixedly mounted on the right collet 15 and is fixedly connected to the thin metal sheet elastomer 1 by fasteners. A lower pad 11 is provided between the right mounting post 13 and the thin metal sheet elastomer 1. An upper pad 10 is provided between the right clamping nut 8 and the thin metal sheet elastomer 1.

[0037] The output voltage of the Wheatstone bridge is denoted as ΔU. The resistance of the first strain gauge 2 is R1, the resistance of the second strain gauge 3 is R2, the resistance of the third strain gauge 4 is R3, and the resistance of the fourth strain gauge 5 is R4. The change in resistance of the first strain gauge 2 is... The resistance change of the second strain gauge 3 is The resistance change of the third strain gauge 4 is The resistance change of the fourth strain gauge 5 is ;

[0038]

[0039] in, The strain value of the first strain gauge 2, The strain value of the second strain gauge 3, The strain value of the third strain gauge 4 This refers to the strain value of the fourth strain gauge 5. That is, the strain value in the y-axis direction at the location of these strain gauges. The stress and strain of the metal sheet of the force sensor in the y-axis direction are mainly caused by the clamping force and the pushing and retracting forces of the guide wire 16, resulting in bending moments and torques on the metal sheet of the force sensor.

[0040] When the left clamp 14 and right clamp 15 clamp the catheter guidewire 16 and apply an advancing or withdrawing force to the catheter guidewire 16: F N This indicates the normal force exerted on the plane of the right chuck 15. F S This indicates the static friction between the guidewire 16 and the plane of the right clamp 15. Tensile strain is generated at the points where both the first strain gauge 2 and the third strain gauge 4 are located. Both the second strain gauge 3 and the fourth strain gauge 5 exhibit compressive strain at their respective locations. Compressive strain is generated at the points where both strain gauge 2 and strain gauge 3 are located. Both the third strain gauge 4 and the fourth strain gauge 5 exhibit tensile strain at their respective locations. Tensile stress is simultaneously generated at the points where the first strain gauge 2, the second strain gauge 3, the third strain gauge 4, and the fourth strain gauge 5 are located. .

[0041] Considering the superposition effect,

[0042] , , = ,

[0043] =

[0044] The output voltage of the bridge is proportional to the force required to advance and retract the guidewire 16, thus achieving the desired purpose.

[0045] More specifically, the circuit of the Wheatstone bridge includes a first strain gauge 2, a second strain gauge 3, a third strain gauge 4, a fourth strain gauge 5, a power supply, and a Wheatstone bridge output terminal; the positive terminal of the power supply is connected to one end of the first strain gauge 2 and one end of the third strain gauge 4, the other end of the first strain gauge 2 is connected to one end of the Wheatstone bridge output terminal and one end of the fourth strain gauge 5, the other end of the third strain gauge 4 is connected to the other end of the Wheatstone bridge output terminal and one end of the second strain gauge 3, and the other end of the fourth strain gauge 5 is connected to the other end of the second strain gauge 3 and the negative terminal of the power supply.

[0046] One feasible implementation method is: due to F N The size is much larger than F s However, the strain gauge's placement always deviates from the ideal position. To eliminate this deviation, the sensor is designed as a thin sheet. This makes the sensor's bending resistance in the z-direction much greater than its bending resistance in the x-direction. F N The resulting bending stress was significantly reduced. In the test, the width of the sheet along the x-axis was 17 mm, the thickness along the z-axis was 2 mm, the strain gauge width was 2 mm, and the minimum distance between strain gauges was 5 mm. Based on the formulas in mechanics of materials, the following can be calculated: F N The resulting bending stress relative to F S The resulting bending stress will be reduced by 20.6 times.

[0047] On the other hand, theoretically, reducing the distance between strain gauges could further reduce [the strain]. F NThe resulting bending stress. However, the test results showed that this was not good, possibly because the torsional stress becomes larger near the center of the sheet, thus affecting the final result.

[0048] The widths of the upper pad 10 and the lower pad 11 can be adjusted so that the center of the clamping surface is flush with the force sensor, which can minimize the torque effect generated by FN on the force sensor.

[0049] It is important to note that the force sensor's elastomer is a thin sheet shape, exhibiting strong bending resistance in the clamping direction but weak bending resistance in the pushing and retracting directions of the guide wire 16. This suppresses bending stress interference from the clamping force and amplifies the measured bending stress values ​​of the pushing and retracting forces. Four strain gauges are arranged vertically to form a full bridge, with strain gauge one and strain gauge two on opposite arms. This arrangement eliminates bending stress generated by the clamping force and amplifies the bending stress caused by the pushing and retracting forces of the guide wire 16. The thickness of the upper pad 10 and lower pad 11 used to mount the force sensor is adjustable, minimizing the torque effect caused by the clamping force.

[0050] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0051] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A sensor structure for catheter guidewire push resistance measurement, characterized by, It includes left chuck (14), right chuck (15), right and left thread screw (6), left clamping nut (7), right clamping nut (8), metal sheet elastomer (1), first strain gauge (2), second strain gauge (3), third strain gauge (4) and fourth strain gauge (5). The left clamping nut (7) and the right clamping nut (8) are respectively installed on the two sides of the axial direction of the right and left thread screw (6), the axial direction of the right and left thread screw (6) is perpendicular to the advancing and retreating direction of the catheter guide wire (16), and one piece of metal sheet elastomer (1) is respectively installed between the left clamping nut (7) and the left chuck (14) and between the right clamping nut (8) and the right chuck (15). The thickness direction of any metal sheet elastomer (1) is parallel to the advancing and retreating direction of the catheter guide wire (16). The first strain gauge (2) and the second strain gauge (3) are vertically attached to one side of the thickness direction of one metal sheet elastomer (1), and the first strain gauge (2) and the second strain gauge (3) are horizontally arranged. The first strain gauge (2) and the second strain gauge (3) are at the same height in the vertical direction. The third strain gauge (4) and the fourth strain gauge (5) are vertically attached to the other side of the thickness direction of one metal sheet elastomer (1), the third strain gauge (4) coincides with the first strain gauge (2) in the thickness direction of the metal sheet elastomer (1), and the fourth strain gauge (5) coincides with the second strain gauge (3) in the thickness direction of the metal sheet elastomer (1). The first strain gauge (2), the second strain gauge (3), the third strain gauge (4) and the fourth strain gauge (5) form a Wheatstone bridge, the first strain gauge (2) and the second strain gauge (3) are on one opposite bridge arm, and the third strain gauge (4) and the fourth strain gauge (5) are on the other opposite bridge arm.

2. The sensor structure for catheter guidewire push resistance measurement of claim 1, wherein, The output voltage of the Wheatstone bridge is denoted as ΔU, the resistance of the first strain gauge (2) is R1, the resistance of the second strain gauge (3) is R2, the resistance of the third strain gauge (4) is R3, and the resistance of the fourth strain gauge (5) is R4. The resistance change of the first strain gauge (2) is , the resistance change of the second strain gauge (3) is , the resistance change of the third strain gauge (4) is , and the resistance change of the fourth strain gauge (5) is . wherein ε1 is a strain value of the first strain gauge (2), ε2 is a strain value of the second strain gauge (3), ε3 is a strain value of the third strain gauge (4), ε4 is a strain value of the fourth strain gauge (5).

3. The sensor structure for catheter guidewire push resistance measurement of claim 2, wherein, When the left chuck (14) and the right chuck (15) clamp the catheter guide wire (16) and give the catheter guide wire (16) a pushing force or a withdrawing force; F N represents the positive pressure on the plane of the right chuck (15), F S represents the static friction between the guide wire (16) and the plane of the right chuck (15), the point where the first strain gauge (2) and the third strain gauge (4) are located both produce tensile strain , the point where the second strain gauge (3) and the fourth strain gauge (5) are located both produce compressive strain , the point where the first strain gauge (2) and the second strain gauge (3) are located both produce compressive strain , the point where the third strain gauge (4) and the fourth strain gauge (5) are located both produce tensile strain , the points where the first strain gauge (2), the second strain gauge (3), the third strain gauge (4), and the fourth strain gauge (5) are located all produce tensile stress .

4. The sensor structure for catheter guidewire push resistance measurement of claim 2, wherein, considering superposition, , , = , .​ 5. The sensor structure for catheter guide wire pushing resistance measurement according to claim 4, wherein, = 。 6. The sensor structure for catheter guidewire push resistance measurement of claim 1, wherein, The left mounting column (12) is fixedly arranged on the left chuck (14), and the right mounting column (13) is fixedly arranged on the right chuck (15).

7. The sensor structure for catheter guidewire push resistance measurement of claim 6, wherein, A lower cushion block (11) is arranged between the left mounting column (12) and the metal sheet elastomer (1). An upper cushion block (10) is arranged between the left clamping nut (7) and the metal sheet elastomer (1).

8. The sensor structure for catheter guidewire push resistance measurement of claim 1, wherein, The right mounting column (13) is fixedly arranged on the right chuck (15), and the right mounting column (13) is fixedly connected with the metal sheet elastomer (1) through fasteners.

9. The sensor structure for catheter guidewire push resistance measurement of claim 8, wherein, A lower cushion block (11) is arranged between the right mounting column (13) and the metal sheet elastomer (1). An upper cushion block (10) is arranged between the right clamping nut (8) and the metal sheet elastomer (1).

10. The sensor structure for catheter guidewire push resistance measurement of claim 1, wherein, The circuit of the Wheatstone bridge comprises a first strain gauge (2), a second strain gauge (3), a third strain gauge (4), a fourth strain gauge (5), a power supply and a Wheatstone bridge output end; The positive pole of the power supply is connected with one end of the first strain gauge (2) and one end of the third strain gauge (4), the other end of the first strain gauge (2) is connected with one end of the Wheatstone bridge output end and one end of the fourth strain gauge (5), the other end of the third strain gauge (4) is connected with the other end of the Wheatstone bridge output end and one end of the second strain gauge (3), and the other end of the fourth strain gauge (5) is connected with the other end of the second strain gauge (3) and the negative pole of the power supply.

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