Flexible joint and instrument arm for flexible endoscopic minimally invasive surgical robot

Abstract

The present invention relates to a flexible joint and an instrument arm for a flexible endoscopic minimally invasive surgical robot; wherein: the flexible joint comprises a columnar continuum, a plurality of parallel outer notches with a triangular longitudinal cross section are provided on the radial outer side of the continuum, and the slot width of the outer notch gradually decreases from the radial outer side to the radial inner side; a plurality of parallel inner notches are provided on the radial inner side of the continuum; the inner notches are the same in shape and slot depth as the outer notches, and are arranged alternately; a plurality of outer notches are symmetrical about a busbar A, a plurality of inner notches are symmetrical about a busbar B, and the busbars A, B and the central axis of the continuum are located on the same plane. The flexible joint of the present invention has a two-degree-of-freedom bending motion that most unidirectional or bidirectional asymmetric slotted flexible joints do not have, significantly improving the flexibility and accessible working space of the continuum joint, and effectively improving the bending controllability of the flexible joint and the safety of surgical operations.

Description

Technical Field

[0001] The present invention relates to the field of medical instruments, and in particular to an instrument arm for a flexible joint and a flexible endoscopic minimally invasive surgical robot. Background Art

[0002] Robot-assisted flexible endoscopic minimally invasive surgery is an emerging technology that applies robotic technology to the medical field. Robots are usually equipped with flexible joints and specific surgical equipment, such as endoscopes and surgical forceps, are installed through flexible joints. When the doctor needs to repair the diseased tissue, the robot carries the surgical instruments to the lesion through the narrow and limited natural cavity of the human body, and adjusts the angle and position of the surgical equipment at the end by changing the posture of the flexible joint to complete the surgical operation. Among them, in the actual application process, the flexible joint not only needs to have sufficient flexibility to adapt to the complex and curved natural cavity, but also needs to have sufficient rigidity to provide a stable support for the surgical instrument to apply sufficient force during operation. However, most of the existing flexible joints are difficult to meet the demand of "rigidity and flexibility, that is, having both flexible and high load-bearing capacity", which leads to many safety hazards during the surgical operation. At the same time, most of the existing flexible joints cannot determine the deformation posture when bending under force, and cannot achieve the expected deformation effect, resulting in the inability to implement precise surgical operations.

[0003] On the other hand, in flexible endoscopic minimally invasive surgical robots, the surgical instruments are placed in concentrated areas, the operating space is limited, and it is difficult to form an operating triangle, which causes the surgical instruments to easily interfere with and collide with each other, limiting the operating field of view and making the operation difficult. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a flexible joint capable of realizing two-degree-of-freedom bending motion and an instrument arm for a flexible endoscopic minimally invasive surgical robot designed on the basis of the flexible joint.

[0005] The technical solution adopted by the present invention to solve the above technical problem is: a flexible joint, including a continuum with a columnar structure, wherein:

[0006] A plurality of parallel outer slots with a triangular longitudinal cross section are provided on the radial outer side of the continuum, and the slot width of the outer slots gradually decreases from the radial outer side to the radial inner side;

[0007] A plurality of parallel inner slots with a triangular longitudinal cross section are provided on the radial inner side of the continuum, and the slot width of the inner slots gradually decreases from the radial inner side to the radial outer side;

[0008] The outer notches and the inner notches have the same shape and depth, and are arranged alternately;

[0009] The plurality of outer notches are symmetrical about a busbar A of the columnar structure continuum, and the plurality of inner notches are symmetrical about a busbar B of the columnar structure continuum. The busbar A, busbar B and the central axis of the continuum are located on the same plane.

[0010] Preferably, the spacing between any adjacent outer notches is the same as the spacing between any adjacent inner notches.

[0011] Preferably, a central hole is provided at the center of the continuum of the columnar structure, and a nickel-titanium alloy rod is provided in the central hole.

[0012] Preferably, the groove depth of the outer notch is greater than the radius of the columnar structure continuum.

[0013] Preferably, the ratio of the groove depth of the outer notch to the diameter of the columnar structure continuum is 0.6-0.9:1.

[0014] Preferably, the ratio of the spacing between adjacent outer notches to the width of the bottom end of the outer notches is 1.2-2:1.

[0015] Preferably, a joint head and a joint tail are provided on the continuum, and the number of outer notches between the joint head and the joint tail is the same as the number of inner notches.

[0016] The present invention also provides an instrument arm for a flexible endoscopic minimally invasive surgical robot, comprising any of the above-mentioned flexible joints, a steel wire flexible shaft, and a front-end deployment mechanism, wherein:

[0017] The flexible joint is provided with a steel wire soft shaft channel;

[0018] The steel wire flexible shaft passes through the steel wire flexible shaft channel and is connected to the front end deployment mechanism;

[0019] The front-end unfolding mechanism can realize opening and closing actions under the push-pull action of the steel wire flexible shaft, and can provide an operating triangle for the surgical instrument in the unfolded state.

[0020] Furthermore, the front-end deployment mechanism includes a deployment mechanism head, two deployment claws, a push rod and two connecting rods; wherein:

[0021] The head of the deployment mechanism is connected to the flexible joint;

[0022] The two deployment claws are symmetrically arranged and are respectively hinged to the head of the deployment mechanism;

[0023] The push rod is connected to the steel wire flexible shaft;

[0024] The two connecting rods are symmetrically arranged with respect to the push rod, and one end of the connecting rod is hinged to the push rod, and the other end is hinged to the corresponding deployment claw; in the deployed state, a triangular operating space can be enclosed between the two deployment claws and the head of the deployment mechanism.

[0025] Preferably, the maximum deployment angle between the two deployment claws is set to 30-33°.

[0026] Compared with the prior art, the present invention has the following advantages and effects:

[0027] 1. The present invention alternately opens triangular slots of longitudinal cross section with the same shape and slot depth on the radial inner side and radial outer side of the continuum, and the triangular slots gradually shrink inward; at the same time, some of the outer slots are symmetrical about the busbar A of the columnar structure continuum, and some of the inner slots are symmetrical about the busbar B of the columnar structure continuum, and the busbar A, busbar B and the central axis of the continuum are located on the same plane; this slot shape and layout arrangement makes the proposed flexible joint based on triangular slot design have two-degree-of-freedom bending motion that most unidirectional or bidirectional asymmetric slotted flexible joints do not have, which significantly improves the flexibility and accessible working space of the continuum joint.

[0028] 2. The flexible joint based on the triangular groove design described in the present invention can achieve a two-degree-of-freedom bending deformation effect, effectively improving the bending controllability of the continuum flexible joint, which is beneficial to improving the safety of surgical operations.

[0029] 3. In the present invention, the spacing between any adjacent outer notches is the same as the spacing between any adjacent inner notches, and the corresponding thicknesses of the joint pieces of each continuum formed between the adjacent outer notches and the inner notches are the same. The flexible joint with this structural design has the characteristics of uniform bending effect, high flexibility and good compliance. On the other hand, compared with other continua in the form of grooves, the flexible joint has the smallest deformation and stress per unit length, is not easy to break, and has a high bearing capacity.

[0030] 4. In the present invention, the nickel-titanium alloy rod is used as the central skeleton and bonded to the two ends of the central hole of the continuum, so that the continuum is constrained at multiple points, which can effectively improve the axial compression resistance of the flexible joint; on the other hand, the nickel-titanium alloy rod has superelasticity and incompressibility. It is set as the central skeleton at the center of the flexible joint, which can further improve the overall load-bearing capacity of the joint on the basis of the original load-bearing performance of the flexible joint.

[0031] 5. In the present invention, by optimizing and adjusting the grooving parameters of the outer notch (inner notch), it is found that when the groove depth P of the outer notch is greater than the radius of the columnar structure continuum, the number of outer notches is the same as the number of inner notches, and the ratio of the spacing between adjacent outer notches to the groove width at the bottom of the outer notch is limited to 1.2-2:1, the flexible joint designed based on the triangular bidirectional asymmetric grooving design has the best load-bearing performance, compliance and anti-torsion ability while realizing two-degree-of-freedom bending.

[0032] 6. In the instrument arm described in the present invention, the front-end deployment mechanism includes an deployment mechanism head, a push rod, two deployment claws and two connecting rods; wherein: the two deployment claws and the two connecting rods are symmetrically arranged, and share a push rod driven by a steel wire flexible shaft, and the two deployment claws are driven to open and close by pushing and pulling the push rod, and a stable "operation triangle area" is formed, thereby effectively avoiding the problem of surgical instruments being easily collided or interfered during the operation. At the same time, the intraoperative field of view is increased. Compared with the design method in which the surgical instruments in the existing flexible endoscopic instrument arm are extended in parallel, the flexibility and effectiveness of the surgical operation are significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0034] Figure 1 It is a schematic diagram of the three-dimensional structure of the flexible joint described in an embodiment of the present invention.

[0035] Figure 2 It is a front view of the flexible joint described in an embodiment of the present invention.

[0036] Figure 3 It is a side view of the flexible joint described in the embodiment of the present invention.

[0037] Figure 4 Schematic diagram of the expected bending posture of the flexible joint in an embodiment of the present invention.

[0038] Figure 5 It is a schematic diagram of the three-dimensional structure of the instrument arm of the flexible endoscopic minimally invasive surgical robot in an embodiment of the present invention.

[0039] Figure 6 Schematic diagram of the structure of the front-end deployment mechanism in an embodiment of the present invention.

[0040] Explanation of reference numerals: 1. continuum; 11. outer notch; 12. inner notch; 13. joint head; 14. joint tail; 2. endoscope channel; 3. instrument channel; 4. water vapor channel; 5. center channel; 51. steel wire flexible shaft; 6. steel wire flexible shaft channel; 7. drive wire channel; 71. drive wire; 8. front end deployment mechanism; 81. deployment mechanism head; 82. push rod; 83. deployment claw; 84. connecting rod. DETAILED DESCRIPTION

[0041] The present invention is further described in detail below in conjunction with embodiments. The following embodiments are for explanation of the present invention but the present invention is not limited to the following embodiments.

[0042] Example 1: Figures 1 to 3 As shown, a flexible joint includes a columnar continuum 1, wherein: the axis extension direction of the columnar continuum 1 is defined as the axial direction of the flexible joint, the direction perpendicular to the axial direction is defined as the radial direction of the flexible joint, one radial side is defined as the radial outer side, and the other radial side is defined as the radial inner side; specifically, the structure of the continuum 1 is set as follows:

[0043] A plurality of parallel outer notches 11 with a triangular longitudinal cross section are provided on the radial outer side of the continuum 1, and the width of the outer notches 11 gradually decreases from the radial outer side to the radial inner side;

[0044] A plurality of inner slots 12 are arranged in parallel and have a triangular longitudinal cross section on the radial inner side of the continuum 1, and the slot width of the inner slots 12 gradually decreases from the radial inner side to the radial outer side;

[0045] The outer notches 11 and the inner notches 12 have the same shape and depth, and are arranged alternately;

[0046] The plurality of outer notches are symmetrical about a busbar A of the columnar structure continuum, and the plurality of inner notches are symmetrical about a busbar B of the columnar structure continuum. The busbar A, busbar B and the central axis of the continuum are located on the same plane.

[0047] The flexible joint described in Example 1 of the present invention can be used in a flexible endoscopic minimally invasive surgical robot system. It has sufficient flexibility to adapt to complex and curved natural cavities and can also provide sufficient support for the stable operation of surgical instruments.

[0048] The flexible joint described in Example 1 of the present invention can realize two-degree-of-freedom bending motion, and its bending posture is as follows: Figure 4 As shown, the two bending planes defining the flexible joint are respectively called the primary bending plane and the secondary bending plane. Through simple finite element simulation, it can be seen that the bending stiffness of the flexible joint in the primary bending plane is the smallest, and the bending stiffness in the secondary bending plane is the largest.

[0049] The working principle of the flexible joint of the present invention having two-degree-of-freedom bending motion characteristics will be specifically described below:

[0050] In the present invention, slots with a triangular longitudinal cross section and the same shape and slot depth are alternately provided on the radial inner side and the radial outer side of the continuum, and the triangular slots gradually shrink inward; at the same time, a plurality of the outer slots are symmetrical about the busbar A of the columnar structure continuum, and a plurality of the inner slots are symmetrical about the busbar B of the columnar structure continuum, and the busbars A and B are located on the same plane as the central axis of the continuum; such slot shape and layout arrangement, as Figure 2 As shown, in the main view, the slot setting of the flexible joint can be regarded as a bidirectional asymmetric form; Figure 3 As shown in the side view, the slot setting of the flexible joint can be approximately regarded as a bidirectional symmetrical form, so that the proposed flexible joint based on the triangular slot design has a two-degree-of-freedom bending motion that most unidirectional or bidirectional asymmetric slot flexible joints do not have (such as Figure 4 ), significantly improving continuum joint flexion flexibility and range of motion.

[0051] On the other hand, the flexible joint based on the triangular groove design can achieve a two-degree-of-freedom bending deformation effect, effectively improving the bending controllability of the continuum flexible joint and improving the safety of surgical operations.

[0052] Furthermore, if Figures 2 to 3 As shown, in this embodiment 1, in order to improve the bending flexibility and bending uniformity of the flexible joint, the spacing between any adjacent outer notches 11 and the spacing between any adjacent inner notches 12 can be set to be the same, so that the thickness of each continuum joint piece formed between any adjacent outer notches 11 and inner notches 12 is also the same. The flexible joint with this structural design has the characteristics of uniform bending effect, high flexibility, and good compliance performance. On the other hand, the designed flexible joint has the smallest deformation and stress per unit length compared with other continua in the form of grooves at the same bending angle, and is not easy to break, and has a high load-bearing capacity.

[0053] Example 2: Figure 1 , Figure 5 As shown, a flexible joint is different from Example 1 in that a central hole 5 is provided at the center of the columnar structure continuum, and a nickel-titanium alloy rod 51 is provided in the central hole 5.

[0054] The flexible joint of the present invention can be bent by wire driving. In order to prevent unnecessary axial compression when the continuum is bent by the wire driving device, a nickel-titanium alloy rod 51 with an outer diameter of 1.2 mm can be used as a central skeleton and placed in the central channel 5. Its two ends are respectively bonded to the distal end and the proximal end of the central channel, so that the continuum is constrained at multiple points, thereby improving the axial compression resistance.

[0055] On the other hand, the nickel-titanium alloy rod is superelastic and incompressible. Setting it as the central skeleton at the center of the flexible joint can further improve the overall load-bearing capacity of the joint based on the original load-bearing performance of the flexible joint.

[0056] Furthermore, if Figure 1 As shown, the flexible joint continuum described in Example 2 of the present invention is also provided with an endoscope channel 2, at least two instrument channels 3, at least two water vapor channels 4 and four drive wire channels 7, so as to carry an endoscope and surgical instruments for functional surgery.

[0057] Example 3: Figure 2 As shown, in order to further improve the load-bearing capacity, anti-torsion performance and related kinematic performance of the flexible joint of the present invention, the present invention uses a finite element simulation method, with the maximum bending angle, the minimum processing wall thickness and the basic dimensions of the shape (total length, diameter) as constraints, and the deflection stiffness in the main bending plane, the bending stiffness in the secondary bending plane and the overall torsional stiffness as targets, and uses the entropy weight method to determine the weights of each optimization target, comprehensively considers and determines the design parameters of the outer notch 11 and the inner notch 12, and performs specific optimization, and the optimization results are as follows:

[0058] Since the outer notch 11 and the inner notch 12 have the same structure, the present invention is specifically described by taking the outer notch 11 as an example:

[0059] like Figure 2 As shown, in the present invention, the spacing between adjacent outer notches 11 is defined as h2, the bottom width of the outer notch is h1, the depth of the outer notch is P, the diameter of the continuum is d, and the length is L;

[0060] (1) The groove depth P of the outer notch is greater than the radius of the columnar structure continuum; preferably, the ratio of the groove depth P of the outer notch to the diameter d of the columnar structure continuum is 0.6-0.9:1;

[0061] (2) The ratio of the spacing h2 between adjacent outer notches 11 and the width h1 of the bottom end of the outer notches is limited to 1.2-2:1;

[0062] (3) A joint head 13 and a joint tail 14 are provided on the continuum, and the number of the outer notches between the joint head 13 and the joint tail 14 is the same as the number of the inner notches.

[0063] When the above limiting conditions are met, the designed flexible joint with triangular bidirectional asymmetric groove design has the best load-bearing performance, compliance and anti-torsion ability while achieving two-degree-of-freedom bending.

[0064] Specifically, in the present invention, taking the case where the diameter d of the flexible joint continuum is 20 mm and the length L is 80 mm, the number of the outer notches is the same as the number of the inner notches, and the number is both 13, according to the above definition, in the control modeling experiment process, the following experimental results can be obtained:

[0065] (1) Continuum kinematic performance: The kinematic performance of a continuum is generally measured by comparing the actual end position of the continuum with the theoretical value of the modeling based on the constant curvature model, and comparing the errors between the two, that is, the positioning error. The smaller the error, the better the constant curvature. In the present invention, compared with the theoretical value of the kinematic model based on the constant curvature assumption, the maximum positioning error of the distal end of the flexible joint is less than 5% of the total length of the continuum flexible joint (80 mm), indicating that the constant curvature is good.

[0066] (2) Hysteresis characteristics: refers to the repeatability of the actual position of the far end of the continuum during the entire motion cycle of bending and recovery, that is, the hysteresis error, which reflects the repeatability of positioning accuracy. In the present invention, the comparison of three experimental values ​​shows that the maximum hysteresis error is less than 2% of the total length, indicating that the repeatability of positioning accuracy is high and has good kinematic characteristics.

[0067] (3) Load-bearing capacity: When the load is 150 g, the deformation deflection of the flexible joint at any bending angle is less than 10% of the total length; when the bending angle is 90°, the effective load is as high as 500 g, indicating that the designed continuum has a high load-bearing capacity;

[0068] (4) Anti-torsion capability: The flexible joint integrated structure design described in the present invention has a higher anti-torsion capability, and its distal end can withstand a certain external force. Experimental results show that its torsional stiffness exceeds 8mNm / °, which is beneficial for providing stable support for surgical instruments during surgery.

[0069] Example 4: Figure 5 As shown, an instrument arm for a flexible endoscopic minimally invasive surgical robot comprises a flexible joint, a steel wire flexible shaft 51 and a front-end deployment mechanism 8 as described in any one of embodiments 1 to 3; wherein:

[0070] A steel wire flexible shaft channel 5 is provided on the flexible joint; the steel wire flexible shaft 51 passes through the steel wire flexible shaft channel 5 and is connected to the front end unfolding mechanism 8; the front end unfolding mechanism 8 can realize opening and closing actions under the push and pull action of the steel wire flexible shaft 51, and can provide a stable triangular operating space for surgical instruments in the unfolded state.

[0071] Specifically, the front-end deployment mechanism 8 that realizes the above-mentioned opening and closing action and can form a triangular operating space is configured as follows:

[0072] The front-end unfolding mechanism 8 includes an unfolding mechanism head 81, two unfolding claws 83, a push rod 82 and two connecting rods 84; wherein: the unfolding mechanism head 81 is connected to a flexible joint; the two unfolding claws 83 are symmetrically arranged and are respectively hinged to the unfolding mechanism head 81; the push rod 82 is connected to the steel wire flexible shaft 51; the two connecting rods 84 are symmetrically arranged about the push rod 82, and one end of the connecting rod 84 is hinged to the push rod 82, and the other end is hinged to the corresponding unfolding claw 83; in the unfolded state, the two unfolding claws 83 and the unfolding mechanism head 81 can enclose a triangular operating space.

[0073] In the instrument arm described in Example 4 of the present invention, the deployment mechanism head 81 is fixedly connected to the distal end of the flexible joint continuum, and its channel layout is consistent with the continuum, and a steel wire soft shaft channel, a drive wire channel, an endoscope channel, a water vapor channel and two surgical instrument channels are respectively set.

[0074] In the instrument arm described in Example 4 of the present invention, the steel wire flexible shaft 51 is connected to the driving device to realize the transmission of force and torque in the curved channel; in the two groups of four-bar mechanisms composed of the deployment mechanism head 81, the push rod 82, the two deployment claws 83 and the two connecting rods 84, the two deployment claws 83 and the two connecting rods 84 are symmetrically arranged and share a push rod 82 driven by the steel wire flexible shaft 51, and the two deployment claws 83 are driven to open and close by pushing and pulling the push rod 82.

[0075] Furthermore, in actual application, the endoscope is finally fixed to the head of the deployment mechanism through the endoscope channel on the continuum, and the two surgical instruments pass through the deployment claws through the instrument channels on the flexible joints of the continuum to guide the deployment mechanism to passively deploy, which is conducive to forming a larger "operation triangle". As a preferred embodiment, in the front-end deployment mechanism, the maximum deployment angle between the two deployment claws is set to 30-33° to ensure that the inner wall of the cavity is not damaged during the operation, thereby improving the safety of the operation.

[0076] In addition, it should be noted that the shapes and names of the parts and components of the specific embodiments described in this specification may be different. Any equivalent or simple changes made based on the structure, features and principles described in the patent concept of the present invention are included in the protection scope of the patent of the present invention. The technicians in the technical field of the present invention can make various modifications or supplements to the specific embodiments described or replace them in a similar manner, as long as they do not deviate from the structure of the present invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A flexible joint, characterized in that: A continuum comprising a columnar structure wherein: A plurality of parallel outer slots with a triangular longitudinal cross section are provided on the radial outer side of the continuum, and the slot width of the outer slots gradually decreases from the radial outer side to the radial inner side; A plurality of inner slots are arranged in parallel and have a triangular longitudinal cross section on the radial inner side of the continuum, and the slot width of the inner slots gradually decreases from the radial inner side to the radial outer side; The outer notches and the inner notches have the same shape and depth, and are arranged alternately; the depth of the outer notches is greater than the radius of the columnar structure continuum; the thickness of each continuum joint piece formed between adjacent outer notches and inner notches is the same; The plurality of outer notches are symmetrical about a generatrix A of the columnar structure continuum, and the plurality of inner notches are symmetrical about a generatrix B of the columnar structure continuum, and the generatrix A, the generatrix B and the central axis of the continuum are located on the same plane; The ratio of the groove depth of the outer notch to the diameter of the columnar structure continuum is 0.6-0.9:1; the ratio of the opening spacing between adjacent outer notches to the groove width at the bottom end of the outer notch is 1.2-2:

1.

2. The flexible joint according to claim 1, characterized in that: The spacing between any adjacent outer notches is the same as the spacing between any adjacent inner notches.

3. The flexible joint according to claim 1 or 2, characterized in that: A central hole is arranged at the center of the continuum of the columnar structure, and a nickel-titanium alloy rod is arranged in the central hole.

4. The flexible joint according to claim 3, characterized in that: The continuum is provided with a joint head and a joint tail, and the number of the outer notches between the joint head and the joint tail is the same as the number of the inner notches.

5. An instrument arm for a flexible endoscopic minimally invasive surgical robot, characterized in that: The invention comprises the flexible joint, the steel wire flexible shaft and the front-end deployment mechanism as described in any one of claims 1 to 4, wherein: The flexible joint is provided with a steel wire soft shaft channel; The steel wire flexible shaft passes through the steel wire flexible shaft channel and is connected to the front-end unfolding mechanism; The front-end unfolding mechanism can realize opening and closing actions under the push-pull action of the steel wire flexible shaft, and can provide an operating triangle for the surgical instrument in the unfolded state.

6. The instrument arm according to claim 5, characterized in that: The front-end deployment mechanism comprises a deployment mechanism head, two deployment claws, a push rod and two connecting rods; wherein: The head of the deployment mechanism is connected to the flexible joint; The two deployment claws are symmetrically arranged and are respectively hinged to the head of the deployment mechanism; The push rod is connected to the steel wire flexible shaft; The two connecting rods are symmetrically arranged with respect to the push rod, and one end of the connecting rod is hinged to the push rod, and the other end is hinged to the corresponding deployment claw; in the deployed state, a triangular operating space can be enclosed between the two deployment claws and the head of the deployment mechanism.

7. The instrument arm according to claim 6, characterized in that: The maximum deployment angle between the two deployment claws is set to 30-33°.

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