Double-rigidity continuum mechanism with rigidity capable of being pre-programmed

Abstract

The invention discloses a double-rigidity continuum mechanism with rigidity capable of being pre-programmed, and relates to the field of surgical instruments. The problem that an existing continuum structure cannot meet the requirement for flexibility of a complex natural orifice minimally invasive surgery while the size is small and driving is easy is solved. A preset cutting part and a connecting section are arranged on a pipe body at the middle rear part of a hollow inner pipe, the connecting section is a fan-shaped body of the pipe body in the circumferential direction, and the preset cutting part is arranged on the connecting section; a back cutting groove and a belly cutting groove are machined in the hollow outer pipe, the hollow outer pipe is coaxially arranged on the hollow inner pipe in a sleeving mode, the belly cutting groove and the connecting section are correspondingly arranged, the rear end of the hollow inner pipe is fixedly connected with the rear end of the hollow outer pipe, and when the external driving device provides pulling force in the axis direction of the hollow inner pipe, the belly cutting groove and the hollow outer pipe are driven to rotate. The hollow inner pipe drives the hollow outer pipe to be bent and deformed, the rear end of the hollow inner pipe is an annular fixing part, and an inner pipe fixing hole is formed in the annular fixing part. The method is used for end execution of the surgical robot.

Description

Technical Field

[0001] The present invention relates to an actuator, and particularly to a dual-stiffness continuum mechanism with programmable stiffness, which can be used for a dual-stiffness programmable continuum structure in the field of minimally invasive medicine. Background Art

[0002] Due to its excellent flexibility, continuum robots can exhibit unique advantages in scenarios such as minimally invasive surgery. In the field of medical devices, it can be used in surgeries such as bronchoscopy, neurosurgery, ophthalmic surgery, otologic surgery, and cardiovascular surgery.

[0003] Continuum robots can reach areas that are difficult for rigid instruments to reach through natural body cavities, or bypass important organs during surgery. There is still a large gap between continuum robots and discrete robots in terms of motion accuracy, load capacity, etc., making it difficult to meet the actual engineering requirements with strict operating requirements. Their motion control is mainly based on open-loop control of the inverse kinematics model, and high-precision modeling and real-time control methods are still lacking. To address this bottleneck problem, relevant researchers are exploring new modeling methods and control theories to improve the accuracy and real-time performance of continuum robots.

[0004] Current continua can provide controllable bending motion. However, for surgical areas with narrow and curved cavity environments such as the kidney, stomach, and cranium, the continuum needs to unfold in a limited space to form a specific spatial configuration and operate on the target surgical site in a specific posture. The design of complex drive mechanisms can meet the requirements but limits size miniaturization, drive simplicity, and surgical instrument integration. At the same time, the high manufacturing cost has become an obstacle to the widespread application of these robots as disposable medical devices.

[0005] Existing various continuum structures, for example: the publication number is CN118305774A, and the patent name is a three-layer sleeve continuum robot. It sets the continuum deformation mechanism as three concentrically nested outer tube, middle tube, and inner tube. One end of the bendable section of the outer tube, middle tube, and inner tube corresponding to the continuum deformation mechanism is fixedly connected, and the parts of the outer tube, middle tube, and inner tube corresponding to the rigid section of the continuum deformation mechanism can move relative to each other along the axis of the continuum deformation mechanism. By fixing any one or two of the outer tube, middle tube, and inner tube, and driving the other one or two of the outer tube, middle tube, and inner tube to move along the axis of the continuum deformation mechanism, the three tubes will generate mutual force effects, so that the bendable section of the continuum deformation mechanism bends and deforms in three-dimensional space, increasing the flexibility of the continuum robot.

[0006] Due to the use of a three-layer sleeve drive, the continuum structure increases the thickness of the continuum robot, resulting in its inability to bend and avoid important organs in a micro-cavity within 1 mm. Additionally, due to the three-layer concentric sleeves set in this mechanism, when performing free bending motion, three driving modules are required to achieve it, causing complex driving. Therefore, it cannot simultaneously meet the flexibility requirements of minimally invasive surgery through complex natural channels. Summary of the Invention

[0007] The purpose of the present invention is to solve the problem that the existing continuum structure cannot simultaneously meet the flexibility requirements of minimally invasive surgery through complex natural channels while being of small size and having simple driving. Furthermore, a dual-stiffness continuum mechanism with programmable stiffness is provided.

[0008] The technical solution of the present invention is as follows:

[0009] A dual-stiffness continuum mechanism with programmable stiffness of the present invention includes a hollow inner tube and a hollow outer tube. A preset cutting part and a connecting section are provided on the middle and rear part of the hollow inner tube on the tube body. The connecting section is a sector of the tube body in the circumferential direction, and the preset cutting part is opened on the connecting section. A back cutting groove and a belly cutting groove are machined on the hollow outer tube. The hollow outer tube is coaxially sleeved on the hollow inner tube, and the belly cutting groove is correspondingly arranged with the connecting section. A fixed connection is provided between the rear ends of the hollow inner tube and the hollow outer tube. When an external driving device provides a pulling force along the axis direction of the hollow inner tube, the hollow inner tube drives the hollow outer tube to undergo bending deformation.

[0010] Further, the rear end of the hollow inner tube is a circular fixing part, and an inner tube fixing hole is opened on the circular fixing part. The front part of the hollow inner tube is a circular inner tube body.

[0011] Further, the preset cutting part is multiple rows of long strip holes.

[0012] Preferably, each row of long strip holes includes a long strip cutting groove in the middle of the inner tube and two semi-long strip cutting grooves in the middle of the inner tube. The long strip cutting groove in the middle of the inner tube is opened on the sector, and the two semi-long strip cutting grooves in the middle of the inner tube are respectively located on the left and right sides of the long strip cutting groove in the middle of the inner tube.

[0013] Further, an outer tube fixing hole corresponding to the position of the inner tube fixing hole is provided at the rear end of the hollow outer tube.

[0014] Preferably, the number of back cutting grooves of the hollow outer tube is 24. Among them, the numbers of the back cutting grooves from the end to the root are from No. 1 to No. 24. The incision angles of the back cutting grooves are all 0 degrees, and their cross-sectional shapes are all rectangular.

[0015] Preferably, the grooving angles of the back cutting grooves from No. 1 to No. 12 are smaller than those of the back cutting grooves from No. 13 to No. 24.

[0016] Preferably, the number of abdominal grooves is 24. Among them, the abdominal grooves are numbered from 1 to 24 from the end to the root, and the groove positions of the abdominal grooves correspond to those of the back grooves; the incision angles of grooves No. 1 - 12 are 45 - 50°, and the incision angles of grooves No. 13 - 24 are 0 - 5°.

[0017] Furthermore, the cross-sectional shapes of grooves No. 1 - 12 on the abdominal grooves are trapezoidal; the cross-sectional shapes of grooves No. 13 - 24 on the abdominal grooves are rectangular.

[0018] Preferably, the grooving angles of grooves No. 1 - 24 on the abdominal grooves are all equal.

[0019] The present invention has the following effects compared with the prior art:

[0020] 1. The present invention is used in a minimally invasive surgical robot system through complex natural cavities. By controlling the end continuum mechanism to expand in a limited space to form a specific spatial configuration, and after the spatial configuration is locked, the part that has not reached the maximum bending limit continues to move to complete relevant surgical operations.

[0021] Compared with a single-segment bending continuum, as a new continuum structure, the present invention has the following functions and effects respectively:

[0022] (1) On a whole continuum, two different stiffnesses are formed by whether to groove, that is: a double-segment bending continuum. Among them, the ungrooved section is a rigid section body, and the grooved section is another rigid section body. Therefore, it is only one continuum and has two stiffnesses, having the advantage of simple structure.

[0023] (2) The sleeving of two layers of tube bodies can achieve a small outer diameter of 0.9 mm, meeting the requirements of avoiding obstacles in small cavities during various surgeries.

[0024] (3) It can generate different bending angles at different stiffness section bodies during the axial stretching of the inner tube under the drive of a single degree of freedom (only one motor and one nut-screw pair), and realizes relatively complex functions through simple driving.

[0025] (4) The present invention also has the advantage of high programmability, specifically reflected in:

[0026] The high programmability is specifically reflected in the editing of the maximum bending angle of the continuum, formula (1):

[0027]

[0028] In the formula, κ i is the limit curvature to be obtained, is the included angle of the incision plane, which is solved by numerical method. H0 is the distance from the neutral layer of the grooved part to the axis plane, and R is the geometric radius of the structure. g and h are fixed parameters of the flexible section except for the bending incision. In this case, κ i is a function related to the included angle and H0. Thus, the parametric design of the limit bending curvature of the continuum robot is completed.

[0029] The high programmability is specifically reflected in the editing of the bending stiffness of the continuum. Formula (2):

[0030]

[0031] In the formula, κ i (φ 2i ) is the bending curvature under the action of the external couple M i , I C (φ 2i ) is the moment of inertia of the cross-section related to the back slotting angle φ 2i , which is solved by numerical method. E is the elastic modulus of the flexible section. The smaller φ 2i , the larger the corresponding I C (φ 2i ), and the greater the stiffness.

[0032] 2. The present invention preset the grooving parameters of the back and abdomen of the joint to adapt to the shape of the human body cavity.

[0033] 3. The present invention designs a continuum flexible arm composed of a series of grooves with different parameters. With a unique joint structure design and a concentric inner tube driving method, it effectively realizes the single-degree-of-freedom bending motion under local structure locking after unfolding in a specific structure in a narrow-scale cavity, effectively meeting the natural cavity structure.

[0034] 4. The present invention has complete functions. The overall actuator driving module has two degrees of freedom, meeting the forward and bending functions of the continuum mechanism, and performing surgical operations through surgical instruments after reaching the specified target position.

[0035] 5. A new single-degree-of-freedom continuum mechanism, as an actuator for natural orifice transluminal endoscopic surgery, can be safely applied to the tortuous natural cavities of the human body in a single-degree-of-freedom driving mode due to its advantages such as small size and simple driving method, realizing two successive independent operations and meeting the specific requirements of forming a specific spatial configuration in a limited space. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is the front view of the overall structure of the present invention; Figure 2 is the schematic diagram of the inner tube; Figure 3 is the schematic diagram of the outer tube; Figure 4It is a cross-sectional view of the inner tube grooving; Figure 5 It is Figure 4 A partial schematic view of the connecting section in Figure 6 It is a cross-sectional view of the outer tube grooving; Figure 7 It is Figure 6 A partial schematic view of the back grooving 2-1 in Figure 8 It is a schematic view of the continuous body bending motion structure. Figure 9 It is an exploded view of the present invention. Figure 10 It is Figure 9 A partial enlarged view at A.

[0037] In the figure: 1, a hollow inner tube, 1-1, a preset cutting part, 1-2, a connecting section, 1-3, an inner tube body, 1-4, an annular fixing part, 1-5, inner tube fixing holes, 1-6, a long strip hole, 1-6-1, a middle long strip grooving of the inner tube, 1-6-2, a middle semi-long strip grooving of the inner tube, 2, a hollow outer tube, 2-1, a back grooving, 2-2, an abdominal grooving. Specific implementation mode

[0038] Specific implementation mode one: Combining Figures 1 to 10 To illustrate this implementation mode, this implementation mode includes a hollow inner tube 1 and a hollow outer tube 2. A preset cutting part 1-1 and a connecting section 1-2 are provided on the middle and rear part of the tube body of the hollow inner tube 1. The connecting section 1-2 is a sector body in the circumferential direction of the tube body, and the preset cutting part 1-1 is opened on the connecting section 1-2; A back grooving 2-1 and an abdominal grooving 2-2 are machined on the hollow outer tube 2. The hollow outer tube 2 is coaxially sleeved on the hollow inner tube 1, and the abdominal grooving 2-2 is correspondingly arranged with the connecting section 1-2. The rear ends of the hollow inner tube 1 and the hollow outer tube 2 are fixedly connected. When an external driving device provides a pulling force along the axial direction of the hollow inner tube 1, the hollow inner tube 1 drives the hollow outer tube 2 to bend and deform.

[0039] The "dual stiffness" of this implementation mode means that the "dual stiffness" means that due to different size groovings on the back of the hollow outer tube, different bending angles are generated under the pulling force of the inner tube.

[0040] Among them, the back grooving 2-1 realizes the bending stiffness of the control mechanism by adjusting the cutting angle and the incision size. In particular, the hollow outer tube 2 is to manufacture 24 sectors with uniform cross-sections and the same thickness on a complete hollow tube body, and the numbers from the end to the root are 1-24. The shapes of the 1-12 incisions are trapezoidal, which can limit their maximum bending angles. The shapes of the 12-24 incisions are rectangular, and their regulation methods have a larger bending range compared with the 1-12 incisions.

[0041] On another complete hollow tube, a series of flexible units with uniform rectangular cut grooves (referring to the connecting section 1-2 with a preset cutting part 1-1) are designed as the driving part for the bending of the outer tube, that is, the hollow inner tube 1. When the hollow inner tube 1 is connected to an external driving device, the driving device is preferably a motor and a nut-screw pair, and the motor drives the hollow inner tube 1 to move horizontally through the nut-screw pair; the hollow inner tube 1 passes through the outer tube, keeping the cutting parts of the two parallel and symmetrically placed away from each other.

[0042] In this embodiment, the shape of the abdominal cut groove 2-2 of the hollow outer tube 2 is a controllable trapezoidal opening while the length of the cut groove remains unchanged. The back cut groove 2-1 of the hollow outer tube 2 changes the moment of inertia of the joint unit through the length of the cut groove, and then determines the final stiffness of the tube body through the moment of inertia.

[0043] The hollow inner tube 1 in this embodiment is provided with a series of uniform preset cutting parts 1-1, preferably rectangular cut grooves, which play a role in driving and adapting to the bending shape of the outer tube.

[0044] Specific Embodiment Two: Figures 9 to 10 Illustrating this embodiment, the rear end of the hollow inner tube 1 in this embodiment is a circular fixed part 1-4, and an inner tube fixing hole 1-5 is provided on the circular fixed part 1-4. Such a setting can ensure accurate positioning of the inner and outer tubes during the assembly process and ensure safe bending deformation in the follow-up. Other compositions and connection relationships are the same as those in Specific Embodiment One.

[0045] Specific Embodiment Three: Figures 9 to 10 Illustrating this embodiment, the front part of the hollow inner tube 1 in this embodiment is a circular inner tube body 1-3. Such a setting ensures coaxial assembly of the inner tube and the outer tube, and makes the inner tube fit the inner wall of the outer tube during the bending deformation process. Other compositions and connection relationships are the same as those in Specific Embodiment One or Two.

[0046] Specific Embodiment Four: Figure 4 and Figure 5 Illustrating this embodiment, the preset cutting part 1-1 in this embodiment is a plurality of long strip holes 1-6. Such a setting reduces the bending stiffness of the inner tube and increases its softness. Other compositions and connection relationships are the same as any one of Specific Embodiments One to Three.

[0047] Specific Embodiment Five: Figure 4 and Figure 5 Illustrating this embodiment, each row of long strip holes 1-6 in this embodiment includes a middle long strip cut groove 1-6-1 of the inner tube and two middle half long strip cut grooves 1-6-2 of the inner tube. The middle long strip cut groove 1-6-1 of the inner tube is opened on a fan-shaped body, and the two middle half long strip cut grooves 1-6-2 of the inner tube are respectively located on the left and right sides of the middle long strip cut groove 1-6-1 of the inner tube.

[0048] With such a setting, the bending stiffness during the bending of the inner tube is further reduced. The other structures and components are the same as any one of the first to fourth specific embodiments.

[0049] Specific Embodiment Six: Combining Figure 7 、 Figure 9 and Figure 10 to illustrate this embodiment, the number of back slots 2-1 on the back of the hollow outer tube 2 in this embodiment is 24. Among them, the back slots 2-1 are numbered from No. 1 to No. 24 from the end to the root. The longitudinal cross-sectional shape of the back slots 2-1 from No. 1 to No. 12 is trapezoidal, and the longitudinal cross-sectional shape of the back slots 2-1 from No. 13 to No. 24 is rectangular.

[0050] With such a setting, the back slot angle of the back of the outer tube with slots is further designed. The corresponding angles of the back slot parts from No. 1 to No. 12 are the same, which is 60°, and the corresponding angles of the cut parts from No. 13 to No. 14 are another angle of 15°. This will result in a large difference in stiffness between the two sections, making the bending difference more obvious during the stretching process. The other compositions and connection relationships are the same as any one of the first to fifth specific embodiments.

[0051] Specific Embodiment Seven: Combining Figure 7 、 Figure 9 and Figure 10 to illustrate this embodiment, the length of the back slots 2-1 from No. 1 to No. 12 in this embodiment is less than the length of the back slots 2-1 from No. 13 to No. 24.

[0052] With such a setting, when the inner tube drives the outer tube to be stretched along the axis, the stiffness of No. 1-12 is smaller than that of No. 13-24, so a larger bending deformation will occur. The other compositions and connection relationships are the same as any one of the first to sixth specific embodiments.

[0053] Specific Embodiment Eight: Combining Figure 7 、 Figure 9 and Figure 10 to illustrate this embodiment, the slotting angle of the back slots 2-1 from No. 1 to No. 12 in this embodiment is 60°.

[0054] With such a setting, No. 1-12 has a smaller stiffness and is more likely to deform during the force application process. The other compositions and connection relationships are the same as any one of the first to seventh specific embodiments.

[0055] Specific Embodiment Nine: Combining Figure 7 、 Figure 9 and Figure 10Describing this embodiment, the grooving angle of the back groove 2-1 from No. 13 to No. 24 in this embodiment is 15°. With such a setting, Nos. 1-12 have greater stiffness and are less likely to deform during the force application process. The other compositions and connection relationships are the same as any one of the first to eighth specific embodiments.

[0056] Specific Embodiment Ten: Combining Figures 1 to 10 Describing this embodiment, Nos. 1-12 in the abdominal groove 2-2 of this embodiment are trapezoidal, and Nos. 13-24 are rectangular and have the same grooving angle.

[0057] With such a setting, during the stretching process of the inner tube, Nos. 1-12 will reach their own bending limit first, and during the continuous stretching process, Nos. 13-24 will continue to undergo bending deformation. The other compositions and connection relationships are the same as any one of the first to ninth specific embodiments.

[0058] Combining Figures 1 to 10 To illustrate the working principle of the present invention:

[0059] After passing through a narrow human body cavity such as the ear canal and entering a relatively open cavity, when further surgical operations need to be performed on the surgical target in the space, during the further bending drive process of the traditional single-degree-of-freedom continuum robot, the continuum mechanism will inevitably touch the passed cavity, which may cause trauma. This continuum robot has the characteristic of different local stiffness. Nos. 1-12 are the low-stiffness part, and Nos. 13-24 are the high-stiffness part, and the stiffness difference between the two is very large in this design process. The continuum robot 1-12 is denoted as the support section, and 13-24 is denoted as the working section. When passing through the narrow channel, the support section reaches the bending limit and cannot be stretched, providing a configuration that conforms to the shape of the cavity for the flexible arm. The working section enters the cavity and further bends under drive, achieving the effect of sequential bending. It can be considered that after the support section of the robotic arm reaches the working configuration first, the working section then performs the operation, realizing the dual-stiffness motion under single-drive stretching.

[0060] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A double-stiffness continuum mechanism with pre-programmable stiffness, characterized in that: It includes a hollow inner tube (1) and a hollow outer tube (2). In the middle and rear part of the hollow inner tube (1), a preset cutting part (1-1) and a connecting section (1-2) are provided on the tube body. The connecting section (1-2) is a sector body in the circumferential direction of the tube body, and the preset cutting part (1-1) is opened on the connecting section (1-2). A back cutting groove (2-1) and a belly cutting groove (2-2) are machined on the hollow outer tube (2). The hollow outer tube (2) is coaxially sleeved on the hollow inner tube (1), and the belly cutting groove (2-2) is correspondingly arranged with the connecting section (1-2). The rear ends of the hollow inner tube (1) and the hollow outer tube (2) are fixedly connected. When an external driving device provides a pulling force along the axis direction of the hollow inner tube (1), the hollow inner tube (1) drives the hollow outer tube (2) to bend and deform.

2. The dual-stiffness continuum mechanism with programmable stiffness according to claim 1, characterized in that: The rear end of the hollow inner tube (1) is a circular ring fixing part (1-4), and an inner tube fixing hole (1-5) is opened on the circular ring fixing part (1-4). The front part of the hollow inner tube (1) is a circular ring-shaped inner tube body (1-3).

3. A dual-stiffness continuum mechanism with programmable stiffness according to claim 2, characterized in that: The preset cutting part (1-1) is a plurality of rows of long strip holes (1-6).

4. The dual-stiffness continuum mechanism with programmable stiffness according to claim 3, characterized in that: Each row of long strip holes (1-6) includes a middle long strip cutting groove (1-6-1) of the inner tube and two middle half long strip cutting grooves (1-6-2) of the inner tube. The middle long strip cutting groove (1-6-1) of the inner tube is opened on the sector body, and the two middle half long strip cutting grooves (1-6-2) of the inner tube are respectively located on the left and right sides of the middle long strip cutting groove (1-6-1) of the inner tube.

5. A dual-stiffness continuum mechanism with programmable stiffness according to claim 4, characterized in that: The rear end of the hollow outer tube (2) is provided with an outer tube fixing hole corresponding to the position of the inner tube fixing hole (1-5).

6. A dual-stiffness continuum mechanism with programmable stiffness according to claim 1 or 5, characterized in that: The number of the back cutting grooves (2-1) of the hollow outer tube (2) is 24. Among them, the numbers of the back cutting grooves (2-1) from the end to the root are from No. 1 to No.

24. The incision angles of the back cutting grooves (2-1) are all 0 degrees, and their cross-sectional shapes are all rectangular.

7. A dual-stiffness continuum mechanism with programmable stiffness according to claim 6, characterized in that: The grooving angles of the back cutting grooves (2-1) from No. 1 to No. 12 are smaller than those of the back cutting grooves (2-1) from No. 13 to No.

24.

8. A dual-stiffness continuum mechanism with programmable stiffness according to claim 7, characterized in that: The number of the belly cutting grooves (2-2) is 24. Among them, the numbers of the belly cutting grooves (2-2) from the end to the root are from No. 1 to No. 24, and the grooving positions of the belly cutting grooves (2-2) correspond to those of the back cutting grooves (2-1). The incision angles of the belly cutting grooves (2-2) from No. 1 to No. 12 are 45-50°, and the incision angles of the belly cutting grooves (2-2) from No. 13 to No. 24 are 0-5°.

9. The dual-stiffness continuum mechanism with programmable stiffness according to claim 8, characterized in that: The cross-sectional shapes of the belly cutting grooves (2-2) from No. 1 to No. 12 are trapezoidal; the cross-sectional shapes of the belly cutting grooves (2-2) from No. 13 to No. 24 are rectangular.

10. A dual-stiffness continuum mechanism with programmable stiffness according to claim 9, characterized in that: The grooving angles of the belly cutting grooves (2-2) from No. 1 to No. 24 are all equal.

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