Variable-rotation-ratio needle puncture surgical robot based on screw pitch transition and design method

Abstract

The invention discloses a variable-rotation-ratio needle puncture surgical robot based on screw pitch transition and a design method. The robot comprises a puncture needle cylinder, a spiral neck bush, a puncture needle, a puncture needle frame and a driving mechanism used for driving the puncture needle frame to rotate. The spiral neck bush is detachably installed on the inner wall of the puncture needle cylinder, a groove in the shape of a preset spiral line is formed in the inner wall of the spiral neck bush, and the preset spiral line at least comprises a first equidistant spiral line, a second equidistant spiral line and a transition spiral line used for connecting the first equidistant spiral line and the second equidistant spiral line. The puncture needle is installed on the puncture needle frame, the spiral neck bush and the puncture needle are coaxially arranged, the puncture needle frame is provided with an extension arm, the extension arm is in sliding connection with the groove, and when the puncture needle frame rotates, the extension arm slides in the groove to drive the puncture needle frame and the puncture needle to linearly move along the axis of the puncture needle while rotating. The puncture needle is simple in structure, good in puncture effect, capable of being customized in a personalized mode and higher in adaptability.

Description

Technical Field

[0001] The present invention relates to the field of biomedical engineering, and particularly to a variable rotation ratio needle puncture surgical robot based on pitch transition and a design method thereof. Background Art

[0002] Needle puncture refers to a method of diagnosing or treating by inserting a needle into the skin or other organs, which is a common technical means in the medical field. The needle puncture process must ensure extremely high precision to prevent excessive damage to surrounding tissues. Due to the disadvantages of low efficiency, low puncture success rate and large tissue damage of manual puncture, the puncture process has gradually begun to be assisted by robots.

[0003] Early research on robot-assisted puncture, such as the CT-based laser guidance system of the Grenoble team in 1992 and Hempel's Innomotion system, focused on planning the puncture path through preoperative imaging, but the real-time adjustment ability was limited. In recent years, scholars have tried to improve the accuracy by optimizing the needle material, designing a flexible mechanical structure or introducing open-loop control.

[0004] All the above-mentioned devices start from the perspective of improving puncture accuracy and adopt various methods to track or plan the puncture path. However, the needle deflection during the puncture process is still inevitable. Especially in thick tissue puncture, the traditional bevel needle tip is more likely to bend unexpectedly due to tissue resistance, resulting in the puncture trajectory deviating from the target position and affecting the puncture accuracy. Although research and experiments have proved that adding a rotational degree of freedom during the needle insertion process can greatly reduce the offset caused by the bevel needle tip, and existing research has partially solved this problem through mechanical modeling, robot-assisted systems and image guidance techniques.

[0005] However, the existing technology still has the following deficiencies: (1) Structural complexity and cost: Most robot-assisted systems require multi-motor coordinated control or rely on high-precision sensors, resulting in large device volume and high cost, making it difficult to popularize. (2) Insufficient adaptability: Traditional screw drive mechanisms usually adopt a fixed lead template and cannot flexibly adapt to the needs of different puncture scenarios, restricting the versatility of the device. (3) The spiral connection of the traditional screw drive mechanism is not smooth. The direct connection of helical lines with different rotational feed ratios will cause speed and acceleration impacts that are not conducive to puncture at the connection point of the two curves, affecting the puncture accuracy and causing unnecessary damage to the tissue. Summary of the Invention

[0006] Object of the Invention: Aiming at the above disadvantages, the present invention provides a variable rotation ratio needle puncture surgical robot based on pitch transition and a design method thereof, which can control the puncture by a single motor, and there is no impact between helical lines with different pitches, the connection is smoother, the puncture efficiency is improved, and the damage to the tissue is reduced.

[0007] Technical solution: To solve the above problems, the present invention adopts a variable rotation ratio needle puncture surgical robot based on pitch transition, which includes a puncture needle cylinder, a spiral inner lining sleeve, a puncture needle, a puncture needle holder, and a driving mechanism for driving the puncture needle holder to rotate; the spiral inner lining sleeve is detachably installed on the inner wall of the puncture needle cylinder, and a groove in the shape of a preset spiral line is formed on the inner wall of the spiral inner lining sleeve. The preset spiral line at least includes a first equidistant spiral line, a second equidistant spiral line, and a transition spiral line for connecting the first equidistant spiral line and the second equidistant spiral line. The pitches of the first equidistant spiral line, the transition spiral line, and the second equidistant spiral line are different, and the spiral line shape functions are also different. The puncture needle is installed on the puncture needle holder, and the spiral inner lining sleeve is coaxially arranged with the puncture needle. An extension arm is provided on the puncture needle holder, and the extension arm is slidably connected to the groove. When the puncture needle holder rotates, the extension arm slides in the groove to drive the puncture needle holder and the puncture needle to move linearly along the axis of the puncture needle while rotating.

[0008] Further, a cylindrical coordinate system (R, θ, z) is established, and the function of the transition spiral line is as follows:

[0009]

[0010] where θ is the angle between the projection of the current point on the XY plane and the positive direction of the X-axis, R is the radius of the spiral inner lining sleeve, P1 is the pitch of the first equidistant spiral line, P2 is the pitch of the second equidistant spiral line, and n is the number of turns of the transition spiral line.

[0011] Further, the driving mechanism includes a driving motor and a driving gear connected to the driving motor. A vertical groove inner lining sleeve is provided in the puncture needle cylinder. The puncture needle holder is fixedly connected to the vertical groove inner lining sleeve, and a transmission gear is provided on the vertical groove inner lining sleeve. The driving gear meshes with the transmission gear.

[0012] Further, it also includes a force sensor bracket and a force sensor. The force sensor bracket is connected to the puncture needle holder, the force sensor is installed on the force sensor bracket, and the force sensor is connected to one end of the puncture needle to measure the axial force on the puncture needle.

[0013] Further, the force sensor bracket and the puncture needle holder are connected by a flat key and a deep groove ball bearing.

[0014] Further, the force sensor and the puncture needle are connected by a thrust ball bearing.

[0015] Further, a detachable cover plate is provided at the top of the puncture needle cylinder, and a card slot for installing the spiral inner lining sleeve is provided on the inner side surface of the puncture needle cylinder.

[0016] Further, it also includes a base. An installation ring is provided on the base, the puncture needle cylinder is installed in the installation ring, and the driving mechanism is fixed on the outer side surface of the installation ring.

[0017] The present invention also provides a design method for the variable rotation ratio needle puncture surgical robot. Different preset spiral shapes are designed for different puncture targets, and the specific steps are as follows:

[0018] S1. Perform X-ray scanning on the puncture target to determine that the thicknesses of the first tissue layer and the second tissue layer are y1 and y2 respectively;

[0019] S2. Determine the optimal rotation feed ratio k otm1 of the first tissue layer and the optimal rotation feed ratio k otm2 of the second tissue layer to determine the pitches P1 and P2 of the first equidistant spiral P1 and the second equidistant spiral, where P1 = k otm1 and P2 = k otm2 ;

[0020] S3. Establish a cylindrical coordinate system (R, θ, z) and determine the transition spiral curve function:

[0021]

[0022] where θ is the angle between the projection of the current point on the XY plane and the positive direction of the X-axis, R is the radius of the spiral inner liner, P1 is the pitch of the first equidistant spiral, P2 is the pitch of the second equidistant spiral, and n is the number of turns of the transition spiral;

[0023] S4. Determine the preset spiral shape function:

[0024]

[0025] The three functions of this function group from top to bottom correspond to the first equidistant spiral, the transition spiral, and the second equidistant spiral respectively;

[0026] S5. Machine the grooves on the inner wall of the spiral inner liner according to the preset spiral shape function, and install the machined spiral inner liner into the puncture needle cylinder for puncture.

[0027] Further, the optimal rotation feed ratios k otm1 and k otm2 are obtained through standard puncture experiments for each tissue.

[0028] Beneficial effects: Compared with the prior art, the remarkable advantages of the present invention are as follows: (1) Through the cooperation of the driving mechanism, the spiral inner lining sleeve and the puncture needle holder, the rotational puncture of the puncture needle is realized, improving the puncture effect. Moreover, the spiral inner lining sleeve can be disassembled and replaced according to different puncture targets, which is more targeted and has stronger adaptability; (2) Through the targeted design of the spiral shape of the spiral inner lining sleeve, especially the shape design of the transition spiral curve, different equidistant spiral lines are more smoothly connected, avoiding sudden changes in speed and acceleration at the connection point of the two curves, which may affect the puncture accuracy and cause unnecessary damage to tissues; (3) The puncture process is driven by a single motor, with a simple structure and convenient use. Brief Description of the Drawings

[0029] Figure 1 It is a schematic diagram of the overall structure of the needle puncture surgical robot of the present invention;

[0030] Figure 2 It is a schematic diagram of the internal structure of the puncture needle cylinder of the present invention;

[0031] Figure 3 It is a schematic diagram of the structure of the puncture needle holder and the force sensor bracket of the present invention;

[0032] Figure 4 It is a schematic diagram of the spiral shape on the spiral inner lining sleeve. Detailed Embodiment

[0033] As Figures 1 to 3 shown, a variable rotation ratio needle puncture surgical robot based on pitch transition in this embodiment includes a base 1, a puncture needle cylinder 3, a spiral inner lining sleeve 5, a puncture needle 12, a puncture needle holder 14, and a driving mechanism. An installation ring 19 is provided on the base 1, and the puncture needle cylinder 3 is installed in the installation ring 19. The driving mechanism is fixed on the outer side surface of the installation ring 19. A detachable cover plate 6 is provided at the top of the puncture needle cylinder 3, and a card slot for installing the spiral inner lining sleeve 5 is provided on the inner side surface of the puncture needle cylinder 3, so that the spiral inner lining sleeve 5 is detachably installed in the puncture needle cylinder 3. A groove with a preset spiral shape is formed on the inner wall of the spiral inner lining sleeve 5, and the shape of the groove can be customized according to different puncture targets.

[0034] A vertical groove inner lining sleeve 7 is further provided in the puncture needle cylinder 3, and the vertical groove inner lining sleeve 7 is located inside the spiral inner lining sleeve 5. The upper and lower ends of the vertical groove inner lining sleeve 7 are fixed in the puncture needle cylinder 3 through an upper bearing 8 and a lower bearing 16. The puncture needle holder 14 is fixedly connected to the vertical groove inner lining sleeve 7. An extension arm 141 is provided on the puncture needle holder 14, a slot is formed on the vertical groove inner lining sleeve 7, and the extension arm 141 passes through the slot and is slidably connected to the groove of the spiral inner lining sleeve 5. The puncture needle 12 is installed on the puncture needle holder 14, and the spiral inner lining sleeve 5 and the puncture needle 12 are coaxially arranged.

[0035] Above the puncture syringe 3, there are also a force sensor bracket 9 and a force sensor 10. The force sensor bracket 9 and the puncture needle bracket 14 are connected by a flat key 4 and a deep groove ball bearing 13 to ensure that the puncture needle bracket 14 and the force sensor bracket 9 are connected in the vertical direction. The top of the force sensor bracket 9 is provided with a connecting rod that extends out of the syringe through the detachable cover plate 6. This connecting rod can only move linearly and cannot rotate. Therefore, when the puncture syringe 3 rotates, the force sensor bracket 9 does not rotate with it but only moves linearly in the axial direction following the puncture syringe 3. The force sensor 10 is installed on the force sensor bracket 9, and the force sensor 10 and the puncture needle 12 are connected by a thrust ball bearing 11 to measure the axial force on the puncture needle 12. Since the axial resistance on the puncture needle 12 is different when puncturing different tissues, the magnitude of the force measured by the force sensor 10 can be used to judge the type of tissue being punctured currently to determine the position of the needle tip. Since the force sensor bracket 9 does not perform rotational motion, it avoids the connection wire of the force sensor 10 from being wound or pulled as the puncture needle bracket 14 rotates, thus ensuring the stable operation of the entire measurement system.

[0036] The driving mechanism includes a driving motor 15 and a driving gear 17 connected to the driving motor 15. The driving motor 15 is fixed on the mounting ring 19. At the bottom of the vertical groove bushing 7, there is a transmission gear 2. The transmission gear 2 is fixedly connected to the vertical groove bushing 7 by an M3 bolt 18. A guiding needle hole for the puncture needle 12 to pass through is opened at the center position of the transmission gear 2. The driving gear 17 meshes with the transmission gear 2. By driving the gear rotation of the driving motor 15, the vertical groove bushing 7, the puncture needle bracket 14 and the puncture needle 12 are driven to rotate. At this time, the extension arm 141 slides in the groove of the spiral bushing 5 to drive the puncture needle 12 to move linearly along its axis while rotating for puncture.

[0037] To achieve the best puncture effect, there are relatively high requirements for the shape design of the groove of the spiral bushing 5. The present invention also provides a method for designing different spiral bushings 5 for different puncture targets, including the following steps:

[0038] S1. Perform X-ray scanning on the puncture target to determine that the thicknesses of the first tissue layer and the second tissue layer are y1 and y2 respectively.

[0039] S2. Determine the optimal rotational feed ratio k otm1 of the first tissue layer and the optimal rotational feed ratio k otm2 of the second tissue layer according to the tissue layer type to determine the pitches P1 and P2 of the first equidistant spiral P1 and the second equidistant spiral, where P1 = k otm1 , P2 = k otm2 . The optimal rotational feed ratios k otm1 , k otm2 are obtained through standard puncture experiments for each tissue.

[0040] S3. Establish a cylindrical coordinate system (R, θ, z) and determine the transition helix curve function:

[0041]

[0042] Among them, θ is the angle between the projection of the current point on the XY plane and the positive direction of the X-axis, R is the radius of the spiral inner liner (5), P1 is the pitch of the first equidistant helix, P2 is the pitch of the second equidistant helix, and n is the number of turns of the transition helix. The upper and lower sections of equidistant helices are more smoothly connected by this transition helix curve, which can avoid sudden changes in speed and acceleration at the connection point of the two curves, thus preventing the impact on puncture accuracy and unnecessary damage to tissues.

[0043] S4. Set the number of turns of the transition curve n = 1, and the calculated height of the transition curve is Determine the preset helix shape function:

[0044]

[0045] The finally determined helix curve is as Figure 4 shown. Curve A is the first equidistant helix, curve B is the transition helix curve, and curve C is the second equidistant helix.

[0046] S5. Machine the groove on the inner wall of the spiral inner liner 5 according to the preset helix shape function, and install the machined spiral inner liner 5 into the puncture syringe 3 for puncture.

[0047] Through the cooperation of the driving mechanism, the spiral inner liner and the puncture needle holder, the present invention realizes the rotary puncture of the puncture needle, improves the puncture effect, and the spiral inner liner can be disassembled and replaced according to different puncture targets, which is more targeted and has stronger adaptability; through the targeted design of the helix shape of the spiral inner liner, especially the shape design of the transition helix curve, different equidistant helices are more smoothly connected, avoiding sudden changes in speed and acceleration at the connection point of the two curves, thus preventing the impact on puncture accuracy and unnecessary damage to tissues; by driving the puncture process with a single motor, the structure is simple and the use is convenient.

Claims

1. A variable rotation ratio needle puncture surgical robot based on pitch transition, characterized in that: The invention comprises a puncture needle barrel (3), a spiral inner sleeve (5), a puncture needle (12), a puncture needle holder (14), and a driving mechanism for driving the puncture needle holder (14) to rotate; the spiral inner sleeve (5) is detachably mounted on the inner wall of the puncture needle barrel (3); the inner wall of the spiral inner sleeve (5) is provided with a groove in the shape of a preset spiral line; the preset spiral line at least comprises a first equidistant spiral line, a second equidistant spiral line, and a transition spiral line for connecting the first equidistant spiral line and the second equidistant spiral line; the first equidistant spiral line, the transition spiral line and the transition spiral line are connected to each other; The pitch of the second equidistant spiral line is different, and the spiral line shape function is also different. The puncture needle (12) is installed on the puncture needle holder (14), and the spiral inner sleeve (5) is coaxially arranged with the puncture needle (12). The puncture needle holder (14) is provided with an extension arm (141), and the extension arm (141) is slidably connected to the groove. When the puncture needle holder (14) rotates, the extension arm (141) slides in the groove to drive the puncture needle holder (14) and the puncture needle (12) to rotate while moving linearly along the axis of the puncture needle (12).

2. The variable rotation ratio needle puncture surgical robot according to claim 1, characterized in that: A cylindrical coordinate system (R, θ, z) is established, and the transition spiral function is as follows: Wherein, θ is the angle between the projection of the current point on the XY plane and the positive direction of the X axis, R is the radius of the spiral inner sleeve (5), P1 is the pitch of the first equidistant spiral line, P2 is the pitch of the second equidistant spiral line, and n is the number of turns of the transition spiral line.

3. The variable rotation ratio needle puncture surgical robot according to claim 1, characterized in that: The driving mechanism comprises a driving motor (15) and a driving gear (17) connected to the driving motor (15); a vertical groove inner sleeve (7) is provided in the puncture needle barrel (3); the puncture needle holder (14) is fixedly connected to the vertical groove inner sleeve (7); a transmission gear (2) is provided on the vertical groove inner sleeve (7); and the driving gear (17) is meshed with the transmission gear (2).

4. The variable rotation ratio needle puncture surgical robot according to claim 1, characterized in that: It also includes a force sensor bracket (9) and a force sensor (10), wherein the force sensor bracket (9) is connected to the puncture needle bracket (14), the force sensor (10) is mounted on the force sensor bracket (9), and the force sensor (10) is connected to one end of the puncture needle (12) to measure the magnitude of the axial force on the puncture needle (12).

5. The variable rotation ratio needle puncture surgical robot according to claim 4, characterized in that: The force sensor bracket (9) is connected to the puncture needle bracket (14) via a flat key (4) and a deep groove ball bearing (13).

6. The variable rotation ratio needle puncture surgical robot according to claim 4, characterized in that: The force sensor (10) is connected to the puncture needle (12) via a thrust ball bearing (11).

7. The variable rotation ratio needle puncture surgical robot according to claim 1, characterized in that: The top of the puncture needle barrel (3) is provided with a detachable cover plate (6), and the inner side surface of the puncture needle barrel (3) is provided with a slot for installing a spiral inner sleeve (5).

8. The variable rotation ratio needle puncture surgical robot according to claim 1, characterized in that: It also comprises a base (1), on which a mounting ring (19) is provided, a puncture needle cylinder (3) is mounted in the mounting ring (19), and a driving mechanism is fixed on the outer surface of the mounting ring (19).

9. A method for designing a variable rotation ratio needle puncture surgical robot according to any one of claims 1 to 8, characterized in that: Different preset spiral shapes are designed for different puncture targets. The specific steps are as follows: S1, performing an X-ray scan on the target to be punctured to determine that the thickness of the first tissue layer and the second tissue layer are y1 and y2 respectively; S2. Determine the optimal rotation feed ratio k of the first tissue layer according to the tissue layer type otm1 , the optimal rotation feed ratio k of the second tissue layer otm2 To determine the pitch of the first equidistant helix P1 and the second equidistant helix P2, where P1 = k otm1 , P2=k otm2 ; S3. Establish a cylindrical coordinate system (R, θ, z) and determine the transition helix curve function: Wherein, θ is the angle between the projection of the current point on the XY plane and the positive direction of the X axis, R is the radius of the spiral inner bushing (5), P1 is the pitch of the first equidistant spiral line, P2 is the pitch of the second equidistant spiral line, and n is the number of turns of the transition spiral line; S4, determine the preset spiral shape function: The three functions of the function group from top to bottom correspond to the first equidistant spiral, the transition spiral and the second equidistant spiral respectively; S5, processing the groove on the inner wall of the spiral inner sleeve (5) according to the preset spiral line shape function, and inserting the processed spiral inner sleeve (5) into the puncture needle barrel (3) for puncture.

10. The design method according to claim 9, characterized in that: The optimal rotation feed ratio k otm1 , k otm2 Obtained by standard puncture experiments for each tissue.

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