A variable stiffness continuum robot based on traction structure

Abstract

The present application relates to the field of continuum robots, and specifically discloses a variable stiffness continuum robot based on a traction structure, which includes a hollow tube central skeleton, intervertebral discs, variable stiffness joints, tendons, traction members, and a locking mechanism. The hollow tube central skeleton runs through a plurality of intervertebral discs and variable stiffness joints arranged at intervals, and each variable stiffness joint is arranged between two adjacent intervertebral discs; at least three tendons are provided, each tendon runs through a plurality of intervertebral discs, and a plurality of tendons are evenly spaced along the circumference of the intervertebral discs; the traction member is used to pull the plurality of variable stiffness joints while sliding along the hollow tube central skeleton, so that each variable stiffness joint approaches the adjacent intervertebral disc along the traction direction; the locking mechanism is used to clamp and lock the tendons as the variable stiffness joints move. The present application can achieve the variable stiffness function by manually controlling the traction line, with low operation risk and high reliability.

Description

Technical Field

[0001] The present application relates to the field of continuum robots, and in particular to a variable stiffness continuum robot based on a pulling structure. Background Art

[0002] In the field of neurosurgery, many diseases involving complex anatomical parts and important areas of the brain require more sophisticated continuum surgical robots to replace manual surgery in order to improve the safety and success rate of surgery.

[0003] The compactness, flexibility, and controllability of a continuum robot primarily depend on its stiffness control. During surgery, the continuum robot must actively bend and deform to maintain a low stiffness state to avoid vital brain tissue and nerves, reducing the distance surgical instruments must move within the brain. High stiffness is required at the site of the lesion, enabling precise and stable surgical operations.

[0004] Slim Slime Robot Ⅱ (SSR-Ⅱ) can meet the needs of active bending deformation, but its disadvantage is that its low stiffness limits its actual load-bearing capacity. When faced with factors such as load and environmental constraints, the accuracy of the robot's movement and the stability of its operation will be greatly affected. Therefore, there is an urgent need to develop a flexible variable stiffness technology that can improve the stiffness of continuum robots. Summary of the Invention

[0005] In order to achieve the regulation of the stiffness of a continuum robot, the present application provides a variable stiffness continuum robot based on a pulling structure.

[0006] The present application provides a variable stiffness continuum robot based on a pulling structure, which adopts the following technical solutions:

[0007] A variable stiffness continuum robot based on a pulling structure, comprising:

[0008] Multiple intervertebral discs arranged at intervals;

[0009] A hollow tubular central skeleton penetrates the plurality of intervertebral discs along the axial direction of the intervertebral discs;

[0010] A plurality of variable stiffness joints are sleeved outside the central skeleton of the hollow tube, each of the variable stiffness joints is located between two adjacent intervertebral discs, and the diameter of the variable stiffness joint is smaller than the diameter of the intervertebral disc;

[0011] at least three tendons, each of the tendons passing through a plurality of intervertebral discs, and the plurality of tendons being equally spaced along the circumference of the intervertebral discs;

[0012] a traction member for traction of the plurality of variable stiffness joints while sliding along the central skeleton of the hollow tube, so that each variable stiffness joint approaches the adjacent intervertebral disc along the traction direction;

[0013] A locking mechanism is used to clamp and lock the tendon as the variable stiffness joint moves.

[0014] The hollow tube central skeleton serves as the support framework for the continuum robot and is connected in series to multiple intervertebral discs. Driven by a stepper motor, the hollow tube central skeleton propels the discs for advancement. Multiple tendons, each driven by a motor, achieve asymmetric expansion and contraction. Tendons of varying lengths control the intervertebral discs' posture, enabling the continuum robot to bend.

[0015] When the continuum robot is subjected to load or performs suturing operations, which require increased strength, multiple variable stiffness joints are pulled by traction parts and slide simultaneously along the central skeleton of the hollow tube. The locking mechanism clamps and locks the tendons as the variable stiffness joints move, thereby increasing the stiffness of the continuum robot.

[0016] Furthermore, the traction member includes at least three traction lines, each traction line runs through the variable stiffness joint and is fixedly connected to the variable stiffness joint, and the multiple traction lines are distributed at equal intervals along the circumference of the variable stiffness joint.

[0017] When the traction line is pulled, multiple variable stiffness joints can be driven to move along the central skeleton of the hollow tube; pulling multiple traction lines at the same time helps to improve the stability of the movement of the variable stiffness joints; the traction line can be controlled manually or by a motor, and the operation is simple.

[0018] Furthermore, the locking mechanism includes a locking ring that is sleeved on the tendon, the inner diameter of the locking ring is adapted to the outer diameter of the tendon, and the locking ring is elastic; two opposite notches are opened on one side of the locking ring, dividing the locking ring into two half rings; the locking mechanism also includes a driving assembly, which is used to drive the two half rings to approach each other and clamp the tendon as the variable stiffness joint moves.

[0019] The setting of the two notches makes it easy for the elastic locking ring to deform under the action of external force. When the tendon is clamped in the locking ring, the two half rings are driven closer to each other by the driving component, so that the tendon can be clamped and locked.

[0020] Furthermore, a sliding hole is opened in the variable stiffness joint along its own radial direction, a push rod is slidably arranged in the sliding hole, and the end of the push rod is fixed to one of the half rings; the driving assembly is used to drive the push rod to move along the sliding hole and squeeze the half ring as the variable stiffness joint moves; a limiting member is provided outside the variable stiffness joint for fixing the relative position of the locking ring and the variable stiffness joint.

[0021] Furthermore, the limiting member includes a fixing ring fixed to the outer wall of the variable stiffness joint, and the fixing ring is sleeved outside the locking ring.

[0022] When the traction member drives the variable stiffness joint to move along the central skeleton of the hollow tube, the driving assembly drives the push rod to move along the sliding hole and squeeze one of the half rings; under the limiting action of the fixed ring, the position of the other half ring remains unchanged, thereby clamping and locking the tendon located between the two half rings.

[0023] Furthermore, the driving assembly includes a sliding member and a first elastic member, an annular cavity is provided in the variable stiffness joint, the sliding member includes a circular ring slidably arranged in the annular cavity and a plurality of locking pins fixed to the circular ring, the locking pins are parallel to the axial direction of the variable stiffness joint and pass through the variable stiffness joint; a first spherical groove is provided on the side wall of the locking pin, and the end of the push rod away from the locking ring abuts against the first spherical groove; a first elastic member is provided in the annular cavity, for driving the sliding member to reset when the traction line loses tension.

[0024] Furthermore, a second elastic member is provided between the variable stiffness joint and the intervertebral disc, for driving the variable stiffness joint to reset when the traction line loses its tension.

[0025] Furthermore, one side of the variable stiffness joint is set as a convex spherical surface, and the side of the intervertebral disc opposite to the variable stiffness joint is provided with a second concave spherical groove that cooperates with the convex spherical surface; when the first elastic member and the second elastic member reach the maximum compression deformation, the convex spherical surface of the variable stiffness joint fits into the second concave spherical groove.

[0026] When the traction line does not apply tension, the first elastic member and the second elastic member are both in an uncompressed state. At this time, there is a gap between the variable stiffness joint and the intervertebral disc, and the end of the locking pin extends out of the variable stiffness joint and has a gap between it and the second concave spherical groove of the intervertebral disc.

[0027] Then, tension is applied to the traction wire. Under the traction of the traction wire, the variable stiffness joint moves along the central skeleton of the hollow tube and approaches the intervertebral disc. The second elastic member is first compressed, reducing the gap between the variable stiffness joint and the intervertebral disc until the second elastic member reaches the maximum compression deformation. At this time, the end of the locking pin abuts against the second concave spherical groove.

[0028] Continue to apply tension to the traction line, the intervertebral disc pushes the locking pin back into the variable stiffness joint, and then pushes the ring to compress the first elastic member; at the same time, relative movement occurs between the locking pin and the push rod, causing the end of the push rod to slide out of the first spherical groove, thereby driving the push rod to move outward along the sliding hole, and then the locking ring clamps the tendon.

[0029] When the first elastic member reaches maximum compression deformation, the end of the push rod completely slides out of the first spherical groove, achieving maximum displacement of the push rod and maximum deformation of the locking ring. The tendon is fully clamped, thereby increasing the stiffness of the continuum robot. At this point, the convex spherical surface of the variable stiffness joint fits tightly against the second concave spherical groove, effectively forming a tight fit between the variable stiffness joint and the intervertebral disc, thereby constraining the curvature of the hollow tube's central skeleton and further increasing the stiffness of the continuum robot.

[0030] When the stiffness of the continuum robot needs to be reduced, the tension of the traction line is removed, and the first elastic member and the second elastic member stretch under the action of their own deformation force, so that the locking pin is reset, and the end of the push rod slides back into the first spherical groove, thereby relieving the pressure of the push rod on the locking ring, and the locking ring loosens the tendon, thereby reducing the stiffness of the continuum robot.

[0031] Furthermore, one end of the push rod abutting against the first spherical groove is a convex spherical surface.

[0032] In this way, the friction between the push rod end and the first spherical groove is reduced, which can reduce wear and tear, and is also conducive to the push rod end sliding smoothly into or out of the first spherical groove, thereby improving the control sensitivity.

[0033] Furthermore, the end of the locking pin away from the ring is configured as a convex spherical surface.

[0034] This reduces the friction between the end of the locking pin and the second concave spherical groove, which is beneficial to reducing wear and improving control sensitivity.

[0035] In summary, this application includes at least one of the following beneficial technical effects:

[0036] The present application provides a variable stiffness continuum robot based on a traction structure, which has a compact structure and occupies a small space. A traction line is used to drive the variable stiffness joint, and then the tendon is clamped and locked through a locking mechanism, providing sufficient stiffness for the continuum robot to complete load and suturing operations. Its variable stiffness function can be achieved by manually controlling the traction line, and the control method is simple, which reduces operational risks and enhances reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a schematic diagram of the overall structure of a variable stiffness continuum robot based on a pulling structure according to an embodiment of the present application;

[0038] Figure 2 This is a partial cross-sectional structural diagram of the embodiment of the present application, mainly used to illustrate the intervertebral disc, variable stiffness joint and locking mechanism;

[0039] Figure 3 This is a partial cross-sectional exploded structural diagram of an embodiment of the present application, mainly used to illustrate an intervertebral disc, a variable stiffness joint, and a locking mechanism;

[0040] Figure 4 It is a schematic diagram of the overall structure of the variable stiffness joint in the embodiment of the present application.

[0041] Figure markings: 1. central skeleton of hollow tube; 2. intervertebral disc; 21. second concave spherical groove; 22. annular groove; 3. variable stiffness joint; 31. sliding hole; 32. fixing ring; 33. annular cavity; 4. tendon; 5. traction line; 6. locking mechanism; 61. locking ring; 611. notch; 612. half ring; 62. push rod; 63. sliding part; 631. circular ring; 632. locking pin; 633. first spherical groove; 64. first elastic part; 7. second elastic part. DETAILED DESCRIPTION

[0042] The following is combined with Figure 1-4 This application is described in further detail.

[0043] The embodiment of the present application discloses a variable stiffness continuum robot based on a pulling structure. Figure 1 The variable-stiffness continuum robot, based on a traction structure, comprises multiple disc-shaped intervertebral discs 2 arranged at intervals. A hollow tubular central skeleton 1 is provided axially through each disc, and the discs 2 are fixedly connected to the skeleton. The skeleton 1 exhibits a certain degree of rigidity and is capable of bending. The skeleton 1, serving as the robot's supporting framework, is driven by a stepper motor, driving the discs 2 to achieve the robot's feed.

[0044] Reference Figure 1 The hollow tube central frame 1 is provided with a plurality of variable stiffness joints 3. Specifically, a through hole is defined in the center of each variable stiffness joint 3 for the hollow tube central frame 1 to pass through. The through hole is larger than the outer diameter of the hollow tube central frame 1, allowing the variable stiffness joint 3 to slide along the hollow tube central frame 1. Each variable stiffness joint 3 is located between two adjacent intervertebral discs 2, and the diameter of each variable stiffness joint 3 is smaller than the diameter of the intervertebral disc 2.

[0045] Reference Figure 1 Flexible tendons 4 are provided through multiple intervertebral discs 2. Three or four tendons 4 can be provided. Tendons 4 are evenly spaced along the circumference of the intervertebral discs 2. One end of each tendon 4 is fixedly connected to the intervertebral disc 2 at the end of the continuum robot. The other end of each tendon 4 is driven by an independent motor, enabling asymmetric expansion and contraction of the multiple tendons 4, thereby controlling the posture of the intervertebral discs 2 and achieving bending of the continuum robot.

[0046] The continuum robot also includes a traction member and a locking mechanism 6. The traction member comprises at least three flexible traction wires 5, each of which runs through and is fixedly connected to multiple variable-stiffness joints 3. The traction wires 5 are evenly spaced around the circumference of the variable-stiffness joints 3. Through holes are provided in the intervertebral disc 2 for the traction wires 5 to pass through, allowing relative sliding between the traction wires 5 and the intervertebral disc 2.

[0047] When the continuum robot is subjected to loads or undergoes suturing operations, requiring increased strength, multiple traction lines 5 are pulled simultaneously, pulling multiple variable-stiffness joints 3 and causing them to slide simultaneously along the hollow central framework 1. This causes each variable-stiffness joint 3 to approach its adjacent intervertebral disc 2 along the traction direction. Locking mechanisms 6 clamp and lock tendons 4 as variable-stiffness joints 3 move, thereby increasing the robot's stiffness.

[0048] Specifically, refer to Figure 2 and Figure 3 The locking mechanism 6 includes a locking ring 61 that fits over the tendon 4. The inner diameter of the locking ring 61 matches the outer diameter of the tendon 4. The locking ring 61 is elastic and can be made of plastic or metal. Two opposing notches 611 are defined on one side of the locking ring 61, dividing it into two halves 612. This allows the locking ring 61 to easily deform under external pressure.

[0049] Further, refer to Figure 2 and Figure 3 The variable stiffness joint 3 has a sliding hole 31 formed in its radial direction. A push rod 62 is slidably disposed in the sliding hole 31, and the end of the push rod 62 is fixedly connected to the outside of one of the half rings 612. The locking mechanism 6 also includes a driving assembly for driving the push rod 62 to move along the sliding hole 31 and squeeze the half ring 612 as the variable stiffness joint 3 moves. A limiting member is provided on the outside of the variable stiffness joint 3 to fix the relative position of the locking ring 61 and the variable stiffness joint 3; specifically, the limiting member includes a fixing ring 32 fixed to the outer wall of the variable stiffness joint 3, and the fixing ring 32 is sleeved on the outside of the locking ring 61.

[0050] When the traction member drives the variable stiffness joint 3 to move along the hollow tube central skeleton 1, the driving assembly drives the push rod 62 to move along the sliding hole 31 and squeeze one of the half rings 612; under the limiting action of the fixed ring 32, the position of the other half ring 612 remains unchanged, thereby clamping and locking the tendon 4 located between the two half rings 612.

[0051] Reference Figure 2 and Figure 3The drive assembly includes a sliding member 63 and a first elastic member 64. The variable-stiffness joint 3 is provided with an annular cavity 33. The sliding member 63 includes a circular ring 631 that slides within the annular cavity 33 and three locking pins 632 fixed to the circular ring 631. The locking pins 632 are parallel to the axial direction of the variable-stiffness joint 3 and extend through the variable-stiffness joint 3. The ends of the locking pins 632 that are away from the circular ring 631 are configured as convex spherical surfaces. A first spherical groove 633 is defined on the sidewall of the locking pin 632. The end of the push rod 62 that is away from the locking ring 61 is configured as a convex spherical surface and abuts the first spherical groove 633.

[0052] The first elastic member 64 is disposed in the annular cavity 33 and is used to drive the sliding member 63 to return to its original position when the pulling wire 5 loses its tension.

[0053] Further, refer to Figure 2 and Figure 3 A second elastic member 7 is provided between the variable stiffness joint 3 and the intervertebral disc 2 for driving the variable stiffness joint 3 to reset when the traction line 5 loses tension. The first elastic member 64 and the second elastic member 7 are both springs.

[0054] According to Figure 2 and Figure 3 One side of the variable stiffness joint 3 is set as a convex spherical surface, and the side of the intervertebral disc 2 opposite to the variable stiffness joint 3 is provided with a second concave spherical groove 21 that matches the convex spherical surface.

[0055] When the traction line 5 does not exert tension, the first elastic member 64 and the second elastic member 7 are both in an uncompressed state. At this time, there is a gap between the variable stiffness joint 3 and the intervertebral disc 2, and the end of the locking pin 632 extends out of the variable stiffness joint 3 (such as Figure 4 As shown), there is a gap between the end of the locking pin 632 and the second concave spherical groove 21 of the intervertebral disc 2.

[0056] Then, tension is applied to the traction wire 5. Under the traction of the traction wire 5, the variable stiffness joint 3 moves along the central skeleton 1 of the hollow tube and approaches the intervertebral disc 2. The second elastic member 7 is first compressed, so that the gap between the variable stiffness joint 3 and the intervertebral disc 2 is reduced until the second elastic member 7 reaches the maximum compression deformation. At this time, the end of the locking pin 632 abuts against the second concave spherical groove 21 on the intervertebral disc 2.

[0057] Continue to apply tension to the traction line 5, the intervertebral disc 2 pushes the locking pin 632 to retract into the variable stiffness joint 3, and then pushes the ring 631 to compress the first elastic member 64; at the same time, there is relative movement between the locking pin 632 and the push rod 62, so that the end of the push rod 62 slides out of the first spherical groove 633, thereby driving the push rod 62 to move outward along the sliding hole 31 and squeeze one side of the locking ring 61, so that the locking ring 61 clamps the tendon 4.

[0058] When the first elastic member 64 reaches maximum compression deformation, the end of the push rod 62 completely slides out of the first spherical groove 633. The push rod 62 reaches its maximum displacement in the sliding hole 31, and the locking ring 61 reaches its maximum deformation. The tendon 4 is fully clamped, thereby increasing the stiffness of the continuum robot. At this point, the convex spherical surface of the variable stiffness joint 3 fits into the second concave spherical groove 21, that is, the variable stiffness joint 3 and the intervertebral disc 2 are tightly fitted, thereby constraining the curvature of the hollow tubular central frame 1 and further increasing the stiffness of the continuum robot.

[0059] Considering that the second elastic member 7 has a certain thickness, in order to make the variable stiffness joint 3 fit closely with the intervertebral disc 2, Figure 3 An annular groove 22 is provided on the intervertebral disc 2 for accommodating the second elastic member 7. The depth of the annular groove 22 is equal to the thickness of the second elastic member 7 in the fully compressed state, so that when the second elastic member 7 is fully compressed, the convex spherical surface of the variable stiffness joint 3 can fit into the second concave spherical groove 21.

[0060] When the stiffness of the continuum robot needs to be reduced, the tension of the traction line 5 is removed, and the first elastic member 64 and the second elastic member 7 stretch under the action of their own deformation force, so that the locking pin 632 is reset, and the end of the push rod 62 slides back into the first spherical groove 633, thereby releasing the pressure of the push rod 62 on the locking ring 61, and the locking ring 61 loosens the tendon 4, thereby reducing the stiffness of the continuum robot.

[0061] In this way, the stiffness of the continuum robot can be adjusted by pulling the traction line 5. On the one hand, the stiffness can be quickly increased or decreased. On the other hand, by controlling the pulling force of the traction line 5, the relative movement between the locking pin 632 and the push rod 62 can be adjusted. In other words, the distance that the push rod 62 moves along the sliding hole 31 can be adjusted, thereby changing the pressure exerted by the push rod 62 on the locking ring 61, and thus adjusting the degree of clamping of the locking ring 61 on the tendon 4, achieving precise control of the stiffness of the continuum robot. The traction line 5 can be controlled manually or by a motor, making it simple and reliable to operate.

[0062] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A variable stiffness continuum robot based on a pulling structure, characterized by: include: Multiple intervertebral discs arranged at intervals; A hollow tubular central skeleton penetrates the plurality of intervertebral discs along the axial direction of the intervertebral discs; A plurality of variable stiffness joints are sleeved outside the central frame of the hollow tube, and each of the variable stiffness joints is located between two adjacent intervertebral discs; at least three tendons, each of the tendons passing through a plurality of intervertebral discs, and the plurality of tendons being equally spaced along the circumference of the intervertebral discs; a traction member for traction of the plurality of variable stiffness joints while sliding along the central skeleton of the hollow tube, so that each variable stiffness joint approaches the adjacent intervertebral disc along the traction direction; A locking mechanism is used to clamp and lock the tendon as the variable stiffness joint moves.

2. The variable stiffness continuum robot based on a pulling structure according to claim 1, characterized in that: The traction member includes at least three traction lines, each of which runs through the variable stiffness joint and is fixedly connected to the variable stiffness joint, and the multiple traction lines are distributed at equal intervals along the circumference of the variable stiffness joint.

3. The variable stiffness continuum robot based on a pulling structure according to claim 2, characterized in that: The locking mechanism includes a locking ring that is sleeved on the tendon, the inner diameter of the locking ring is adapted to the outer diameter of the tendon, and the locking ring is elastic; two opposite notches are opened on one side of the locking ring, dividing the locking ring into two half rings; the locking mechanism also includes a driving component for driving the two half rings to approach each other and clamp the tendon as the variable stiffness joint moves.

4. The variable stiffness continuum robot based on a pulling structure according to claim 3, characterized in that: A sliding hole is opened in the variable stiffness joint along its own radial direction, and a push rod is slidably arranged in the sliding hole, and the end of the push rod is fixedly connected to one of the half rings; the driving assembly is used to drive the push rod to move along the sliding hole and squeeze the half ring as the variable stiffness joint moves; a limiting member is provided outside the variable stiffness joint for fixing the relative position of the locking ring and the variable stiffness joint.

5. The variable stiffness continuum robot based on a pulling structure according to claim 4, characterized in that: The limiting component includes a fixing ring fixed to the outer wall of the variable stiffness joint, and the fixing ring is sleeved outside the locking ring.

6. The variable stiffness continuum robot based on a pulling structure according to claim 5, characterized in that: The driving assembly includes a sliding member and a first elastic member. An annular cavity is provided in the variable stiffness joint. The sliding member includes a circular ring slidably arranged in the annular cavity and a plurality of locking pins fixed to the circular ring. The locking pins are parallel to the axial direction of the variable stiffness joint and pass through the variable stiffness joint. A first spherical groove is provided on the side wall of the locking pin, and the end of the push rod away from the locking ring abuts against the first spherical groove. A first elastic member is provided in the annular cavity, and is used to drive the sliding member to reset when the traction line loses tension.

7. The variable stiffness continuum robot based on a pulling structure according to claim 6, characterized in that: One end of the push rod abutting against the first spherical groove is in the form of a convex spherical surface.

8. The variable stiffness continuum robot based on a pulling structure according to claim 6, characterized in that: A second elastic member is provided between the variable stiffness joint and the intervertebral disc, and is used for driving the variable stiffness joint to reset when the traction line loses its tension.

9. The variable stiffness continuum robot based on a pulling structure according to claim 8, characterized in that: One side of the variable stiffness joint is set as a convex spherical surface, and the side of the intervertebral disc opposite to the variable stiffness joint is provided with a second concave spherical groove that cooperates with the convex spherical surface; when the first elastic member and the second elastic member reach the maximum compression deformation, the convex spherical surface of the variable stiffness joint fits into the second concave spherical groove.

10. The variable stiffness continuum robot based on a pulling structure according to claim 6, characterized in that: One end of the locking pin away from the circular ring is configured as a convex spherical surface.

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