Variable stiffness pipe and continuum robot variable stiffness module

Abstract

The invention discloses a variable stiffness pipe and a continuum robot variable stiffness module, and relates to the technical field of continuum robotics.The variable stiffness pipe comprises a flexible inner pipe and a flexible outer pipe arranged outside the flexible inner pipe in a sleeving mode, and a phase change material and a flexible heat exchange device are arranged between the flexible inner pipe and the flexible outer pipe; the heat exchange device can exchange heat with the phase-change material and enable the phase-change material to be changed from a solid phase to a liquid phase, a flexible pipe is further arranged in the filling space, a plurality of hollow groove sets are formed in the pipe wall of the flexible pipe in a penetrating mode, the hollow grooves are filled with the phase-change material, the flexible pipe can be freely bent when the phase-change material is in the liquid phase, and the flexible pipe can be bent when the phase-change material is in the solid phase. According to the variable-stiffness continuum robot, the shear modulus resisting shear deformation under the shear stress is converted into the compression modulus resisting compression deformation under the compression stress, the stiffness of the variable-stiffness pipe can be improved, the variable-stiffness continuum robot comprises the variable-stiffness pipe and a control mechanism, and the variable-stiffness continuum robot can be controlled by controlling the stiffness of the variable-stiffness pipe to change. And the motion control module is matched to move towards the target position and control the surgical tool.

Description

Technical Field

[0001] The invention relates to the technical field of continuum robots, in particular to a variable stiffness tube and a variable stiffness module of a continuum robot. Background Art

[0002] Stiffness refers to the ability of a material to resist deformation. Variable stiffness pipe is a pipe whose stiffness can change. This pipe can change its stiffness characteristics according to the change of external temperature to adapt to different engineering application requirements. Compared with traditional fixed stiffness pipes, variable stiffness pipes have better flexibility and adaptability. In the field of continuum robotics, how to adjust or control stiffness to meet different task requirements has become an important research topic. For example, in minimally invasive surgery or natural orifice endoscopic surgery, the continuous robot needs to be in a low stiffness state to minimize the side effects on the patient when it is inserted into the human body. When it reaches the target area, it needs to be transferred to a high stiffness level to transmit the force and ensure the accuracy of movement to reduce trauma. Therefore, variable stiffness tubes have been widely used in the field of continuum robotics. Existing variable stiffness tubes are usually filled with phase change materials in the inner cavity of the tube body. The variable stiffness tube is stiffened by making the phase change material in a solid phase. However, when subjected to shear deformation, the stiffness of the variable stiffness tube is mainly affected by the shear modulus of the material. Since the shear modulus of the phase change material is much lower than the compression modulus, the stiffness of the tube body is low under the action of shear force, and the tube body will experience large deformation. Summary of the invention

[0003] The purpose of the present invention is to provide a variable stiffness tube and a variable stiffness module of a continuum robot to solve the problems existing in the above-mentioned prior art, improve the stiffness of the tube body under the action of shear force, and reduce the deformation of the tube body under the action of shear force when the phase change material is in the solid phase.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] The present invention provides a variable stiffness tube, comprising a flexible inner tube and a flexible outer tube sleeved outside the flexible inner tube, a filling space with closed ends formed between the flexible inner tube and the flexible outer tube, a phase change material and a flexible heat exchange device arranged in the filling space, the heat exchange device being able to exchange heat with the phase change material and change the phase change material from a solid phase to a liquid phase, a flexible tube being further arranged in the filling space, a plurality of hollow groove groups being opened through the tube wall of the flexible tube, the hollow groove group comprising at least one hollow groove, the hollow groove being filled with the phase change material, and when the phase change material is in a liquid phase, the phase change material being able to flow freely, and the flexible tube being able to bend freely.

[0006] Preferably, the heat exchange device can also exchange heat with the phase change material to change the phase change material from a liquid phase to a solid phase.

[0007] Preferably, each of the hollow grooves in the hollow groove group is arranged along the circumference of the flexible tube, each of the hollow grooves extends along the circumferential direction of the flexible tube, and the sum of the circumferences of each of the hollow grooves in the hollow groove group is smaller than the circumference of the flexible tube, and each of the hollow grooves in a plurality of the hollow groove groups is axially staggered on the flexible tube, and along the axial direction, the projections of all the hollow grooves in any adjacent hollow groove groups on the cross section of the flexible tube completely cover the cross section.

[0008] Preferably, the heat exchange device comprises a flexible heat exchange tube, in which a heat exchange medium flows to exchange heat with the phase change material.

[0009] Preferably, the flexible heat exchange tube has one, and the flexible heat exchange tube is spirally and seamlessly wound outside the flexible inner tube.

[0010] Preferably, there are a plurality of flexible heat exchange tubes, each of which is alternately spirally wound at a certain angle, and each of which is wound around the outside of the flexible inner tube.

[0011] Preferably, the heat exchange device comprises a heating wire, which is spirally wound outside the flexible tube and is used to connect to a power source and heat the phase change material.

[0012] Preferably, it also includes a seal, two of which are arranged at both ends of the flexible inner tube and the flexible outer tube, and the seal can fit the outer wall of the flexible inner tube and the inner wall of the flexible outer tube to seal the two ends of the filling space.

[0013] Preferably, the phase change material is a low melting point alloy.

[0014] The present invention also provides a variable stiffness module for a continuum robot, comprising a variable stiffness tube as described in any one of the above items and a control mechanism, wherein the control mechanism is connected to the heat exchange device, and the control mechanism is used to control the heat exchange device.

[0015] Compared with the prior art, the present invention has achieved the following technical effects:

[0016] The present invention provides a variable stiffness tube. A heat exchange device arranged between a flexible outer tube and a flexible inner tube can exchange heat with a phase change material, thereby controlling the phase change of the phase change material. The phase change material is filled in a hollow groove. When the phase change material is cooled to make the phase change material in a solid phase, the flexible tube bends in the direction of the shear force under the action of the shear force, and the spacing between the side walls on both sides of the hollow groove of the flexible tube becomes smaller. The side walls of the flexible tube on both sides of the hollow groove will produce an extrusion effect on the phase change material in the hollow groove, so that the shear stress of the flexible tube is converted into the compressive stress of the phase change material in the hollow groove of the flexible tube, so that the shear modulus of the flexible tube resisting shear deformation under shear stress is converted into the compression modulus of the phase change material in the hollow groove resisting compression deformation under compressive stress, so as to improve the stiffness of the variable stiffness tube.

[0017] The present invention also provides a variable stiffness module for a continuum robot. The doctor controls the change in stiffness of the variable stiffness tube through a control mechanism and provides heat to the phase change material through a heat exchange device, so that the phase change material is heated up and changes from a solid phase to a liquid phase. The variable stiffness tube can bend freely and move to a target position in cooperation with the motion control module of the continuum robot. It can become softer when passing through narrow passages and better adapt to the complex curved pipes and chamber structures inside the human body, such as blood vessels and intestines, so that it can reach the surgical site more smoothly, reduce damage to surrounding tissues, and improve the safety of the operation. After confirming that the surgical tool has reached the surgical site through imaging means, the heat of the phase change material is absorbed by the human body temperature or the heat exchange device, so that the phase change material is cooled and changes from a liquid phase to a solid phase. The solid phase change material in the hollow groove of the flexible tube is used to increase the stiffness of the variable stiffness tube, and the force is transmitted through the variable stiffness tube and applied to the surgical tool so that the surgical tool completes the specified action. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] 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 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 work.

[0019] Figure 1 An exploded schematic diagram of a variable stiffness tube structure in one implementation manner;

[0020] Figure 2 A cross-sectional view of a variable stiffness tube structure in one embodiment;

[0021] Figure 3 A schematic diagram of a nested structure of a flexible heat exchange tube, a flexible tube and an electric heating wire in one embodiment;

[0022] Figure 4 A schematic diagram of a flexible pipe structure in one embodiment;

[0023] Figure 5 A front view of a flexible pipe structure in one embodiment;

[0024] Figure 6 is a cross-sectional view of a flexible pipe structure AA in one embodiment;

[0025] Figure 7 This is a schematic diagram of the structure of a flexible heat exchange tube in one embodiment;

[0026] Figure 8 A schematic diagram of the structure of a flexible heat exchange tube in another embodiment;

[0027] Fig. 9 This is a schematic diagram of a sealing structure in one embodiment;

[0028] In the figure: 1-flexible inner tube; 2-flexible outer tube; 3-filling space; 4-heat exchange device; 41-flexible heat exchange tube; 42-electric heating wire; 5-flexible tube; 51-hollow groove group; 6-sealing element; 61-first through hole; 62-second through hole; 7-phase change material. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] The purpose of the present invention is to provide a variable stiffness tube and a variable stiffness module of a continuum robot to solve the problems existing in the above-mentioned prior art, improve the stiffness of the tube body under the action of shear force, and reduce the deformation of the tube body under the action of shear force when the phase change material is in the solid phase.

[0031] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] Embodiment 1

[0033] This embodiment provides a variable stiffness tube, such as Figures 1 to 9As shown, it includes a flexible inner tube 1 and a flexible outer tube 2 sleeved outside the flexible inner tube 1, a filling space 3 with closed ends is formed between the flexible inner tube 1 and the flexible outer tube 2, a phase change material 7 and a flexible heat exchange device 4 are arranged in the filling space 3, the heat exchange device 4 can exchange heat with the phase change material 7 and change the phase change material 7 from a solid phase to a liquid phase, a flexible tube 5 is also arranged in the filling space 3, a plurality of hollow groove groups 51 are opened through the tube wall of the flexible tube 5, the hollow groove group 51 includes at least one hollow groove, the hollow groove is filled with the phase change material 7, when the phase change material 7 is in a liquid phase, the phase change material 7 The flexible tube 5 can flow freely and bend freely. When the phase change material 7 is in the solid phase, the flexible tube 5 will bend in the direction of the shear force under the action of the shear force, and the spacing between the side walls on both sides of the hollow groove group of the flexible tube becomes smaller. The side walls of the flexible tube on both sides of the hollow groove will squeeze the phase change material in the hollow groove, so that the shear stress of the flexible tube 5 is converted into the compressive stress of the phase change material 7 in the hollow groove of the flexible tube 5, so that the shear modulus of the flexible tube 5 resisting shear deformation under shear stress is converted into the compression modulus of the phase change material in the hollow groove resisting compressive deformation under compressive stress, so as to improve the stiffness of the variable stiffness tube.

[0034] In another preferred implementation of this embodiment, the flexible tube 5 is made of stainless steel. Stainless steel has high strength and can bear greater forces. Stainless steel also has good plasticity and toughness. Stainless steel can be manufactured and formed through a variety of processing techniques, such as forging, rolling, extrusion, stretching, stamping, welding, cutting, etc., which can meet the production of products with different shapes, sizes and precision requirements. Stainless steel itself is non-toxic and harmless, will not release harmful substances, and has no harm to human health and the environment. It is widely used in the field of medical device technology.

[0035] In another preferred implementation of this embodiment, the material of the flexible tube 5 is titanium alloy. Titanium alloy has high strength and light weight, and has good biocompatibility, and is one of the ideal choices for medical implant materials.

[0036] In another preferred implementation of this embodiment, the heat exchange device 4 can also exchange heat with the phase change material 7 to change the phase change material 7 from liquid phase to solid phase, so as to improve the efficiency of the phase change material 7 changing from liquid phase to solid phase, so that the phase change material 7 has rigidity as soon as possible to withstand the force.

[0037] In another preferred implementation of this embodiment, Figures 4 to 6As shown, each hollow groove in the hollow groove group 51 is arranged along the circumferential direction of the flexible tube 5, and each hollow groove extends along the circumferential direction of the flexible tube 5, and the sum of the circumferences of the hollow grooves in the hollow groove group 51 is less than the circumference of the flexible tube 5 to ensure the continuity of the flexible tube 5, and each hollow groove in a plurality of hollow groove groups is staggered along the circumferential direction on the flexible tube to reduce the bending stiffness of the flexible tube on the cross section where the hollow groove is located, and along the axial direction, the projections of all the hollow grooves in any adjacent hollow groove group 51 on the cross section of the flexible tube 5 completely cover the cross section, so that the variable stiffness tube can bend freely when the phase change material 7 is in liquid phase.

[0038] In another preferred implementation of this embodiment, Figures 4 to 6 As shown, the width of the hollow grooves in the axial direction of the flexible tube 5 should be as narrow as possible, preferably 0.1-0.5 mm, the density of the hollow grooves should be as large as possible, and the spacing between adjacent hollow grooves is preferably 0.1-0.5 mm. By reducing the width and spacing of the hollow grooves in the axial direction, the hollow grooves are densely distributed on the side wall of the flexible tube, reducing the restriction of the side wall of the flexible tube on the bending of the flexible tube, so as to increase the curvature of the variable stiffness tube when bending. Preferably, the hollow groove group includes two hollow grooves symmetrically arranged in the circumferential direction of the flexible tube, and the angle between the line connecting the starting end of each hollow groove to the axis of the flexible tube 5 and the line connecting the terminal end of the hollow groove to the axis of the flexible tube 5 is preferably 140°-175°. By expanding the angle of the hollow groove, the area of ​​the remaining flexible tube wall is reduced, thereby reducing the bending stiffness of the flexible tube when the phase change material is in liquid phase. The symmetry axes of any two adjacent hollow groove groups are orthogonally arranged to avoid inconsistent bending stiffness of the flexible tube in various directions. Through the above arrangement, the variable stiffness tube has sufficient flexibility when the phase change material 7 is in liquid phase.

[0039] In another preferred implementation of this embodiment, the processing method of the hollow groove group 51 can be to perform wire cutting on the flexible tube 5, using a continuously moving thin metal wire as a tool electrode to perform pulse spark discharge etching on the rigid support hanger to remove the tube wall, thereby achieving high-precision cutting and forming.

[0040] In another preferred implementation of this embodiment, the shape of the hollow groove group 51 can be rectangular, or can be other shapes such as ellipse, and is densely arranged on the flexible tube 5 so that the bending stiffness of the flexible tube 5 is close to zero stiffness when the phase change material 7 is in liquid phase.

[0041] In another preferred implementation of this embodiment, Figure 3 and Figure 7As shown, the heat exchange device 4 includes a flexible heat exchange tube 41, in which a heat exchange medium flows to exchange heat with the phase change material 7. When the flexible heat exchange tube 41 heats the solid phase change material, the heat exchange medium can provide heat for the phase change material. With the continuous input of heat, the temperature of the phase change material 7 will gradually increase. Once the specific melting point of the phase change material 7 is reached, the phase change material 7 will begin to change from solid to liquid. When the liquid phase change material 7 is cooled, the heat exchange medium can absorb the heat of the phase change material, and the heat will gradually be transferred from the phase change material 7 to the flexible heat exchange tube 41. As the temperature of the phase change material 7 continues to decrease, when it reaches its solidification point, the phase change material 7 will change from liquid to solid.

[0042] In another preferred implementation manner of this embodiment, when the heat exchange medium provides heat for the phase change material, it can be warm water with a temperature of 50-100°C, or silicone oil with a temperature of 50-150°C; when the heat exchange medium is used to absorb the heat of the phase change material, it can be cold water with a temperature of 0-30°C, or liquid nitrogen with a temperature below -196°C.

[0043] In another preferred implementation of the present embodiment, the flexible inner tube 1 and the flexible outer tube 2 are made of polydimethylsiloxane (PDMS) or silicone, and a thermal insulation coating is coated on the surface so that the tube wall has a strong thermal insulation ability, which can avoid damage to human tissue caused by the variable stiffness tube when the heat exchange medium is passed.

[0044] In another preferred implementation of this embodiment, Figure 7 As shown, the flexible heat exchange tube 41 has a spiral seamless winding outside the flexible inner tube 1. By seamlessly winding the flexible heat exchange tube 41 on the outside of the flexible inner tube 1, the contact area between the flexible heat exchange tube 41 and the phase change material 7 per unit length of the variable stiffness tube is increased, thereby improving the heat exchange efficiency between the flexible heat exchange tube 41 and the phase change material 7.

[0045] In another preferred implementation of this embodiment, Figure 8 As shown, there are multiple flexible heat exchange tubes 41, preferably two, and the multiple flexible heat exchange tubes 41 are arranged in parallel outside the flexible inner tube 1. By arranging multiple flexible heat exchange tubes 41, the contact area between each flexible heat exchange tube 41 and the phase change material 7 is reduced, and the flow rate of the heat exchange medium is increased. Each flexible heat exchange tube 41 can simultaneously exchange heat with the phase change material 7 within the contact range, so that the phase change material 7 within the contact range of each flexible heat exchange tube 41 reaches the critical temperature as soon as possible, thereby improving the heat exchange efficiency between the flexible heat exchange tube 41 and the phase change material 7.

[0046] In another preferred implementation of the present embodiment, there are multiple flexible heat exchange tubes 41, each of which is spirally arranged in the filling space between the flexible inner tube and the flexible outer tube, and each of which can simultaneously exchange heat with the phase change material to improve the heat exchange efficiency between the flexible heat exchange tube and the phase change material.

[0047] In another preferred implementation of this embodiment, there are multiple flexible heat exchange tubes 41, each of which is alternately spirally wound at a certain angle, and each flexible heat exchange tube is wound outside the flexible inner tube to exchange heat with the phase change material.

[0048] In another preferred implementation of this embodiment, there are multiple flexible heat exchange tubes 41, and the flexible heat exchange tubes are cross-wound with each other at a certain angle to form a braided tube network, which is wound around the flexible inner tube to exchange heat with the phase change material.

[0049] In another preferred implementation of the present embodiment, the material of the flexible heat exchange tube 41 may be polytetrafluoroethylene (PTFE). Polytetrafluoroethylene has good heat resistance and does not react with the ambient medium, and can maintain sufficient stability during the heat exchange process with the phase change material.

[0050] In another more preferred implementation of this embodiment, the material of the flexible heat exchange tube 41 can be a capillary copper tube or a capillary stainless steel tube. The capillary copper tube has good chemical stability and fluid transmission performance. Under a certain pressure difference, it can achieve precise small-flow fluid transmission and is suitable for equipment that requires micro-fluid control, such as micro-injection devices in medical equipment.

[0051] In another preferred implementation of this embodiment, the material of the flexible heat exchange tube 41 can be carbon fiber reinforced resin, which is made of carbon fiber, thermosetting or high-temperature resistant thermoplastic resin as main raw materials, and has high thermal conductivity, good corrosion resistance, light weight and high strength.

[0052] In another preferred implementation of this embodiment, Figure 3 As shown, the heat exchange device 4 includes a heating wire 42, which is spirally wound outside the flexible tube 5. The heating wire 42 is used to connect to a power source and heat the phase change material 7. By heating the phase change material 7, the phase change material 7 changes from a solid state to a liquid state. Under the action of normal human body temperature, the phase change material 7 changes from a liquid state to a solid state.

[0053] In another preferred implementation of the present embodiment, there are multiple heating wires 42, which are spirally arranged between the flexible inner tube 1 and the flexible outer tube 2. The heating wires 42 are used to connect to a power source and heat the phase change material 7. By heating the phase change material 7, the phase change material 7 changes from a solid state to a liquid state. Under the action of normal human body temperature, the phase change material 7 changes from a liquid state to a solid state.

[0054] In another preferred implementation of this embodiment, Figure 3 As shown, the flexible heat exchange tube 41 is spirally and seamlessly wound outside the flexible inner tube, and is used for exchanging heat with the phase change material 7 between the flexible inner tube 1 and the flexible tube 5. The heating wire 42 is wound outside the flexible tube 5, and is used for exchanging heat with the phase change material 7 between the flexible tube 5 and the flexible outer tube 2. In summary, the heat exchange device 4 is provided on both the inner and outer sides of the flexible tube 5 to improve the heat exchange efficiency between the heat exchange device 4 and the phase change material 7.

[0055] In another preferred implementation of this embodiment, the specific winding spacing and winding method of the heating wire 42 can be reasonably determined according to the required heating power.

[0056] In another more preferred implementation of the present embodiment, the heat exchange device 4 includes an optical fiber, on which a grating is arranged, and the optical fiber is arranged between a flexible inner tube and a flexible outer tube. Light propagates in the optical fiber and is guided to the phase change material through the grating, so that the optical fiber and the phase change material exchange heat. Based on the thermal motion of microscopic particles (such as atoms, molecules, etc.) inside the optical fiber material, heat is transferred from a higher temperature area to a lower temperature area through mutual collision.

[0057] In another preferred implementation of this embodiment, Fig. 9 As shown, the variable stiffness tube also includes a seal 6, which is arranged at both ends of the flexible inner tube 1 and the flexible outer tube 2. The seal 6 can fit the outer wall and the inner wall of the flexible inner tube, and is used to seal the filling space 3 between the flexible inner tube 1 and the flexible outer tube 2 to prevent the phase change material 7 between the flexible inner tube 1 and the flexible outer tube 2 from falling out of the filling space 3, and support the flexible tube 5 and the heat exchange device 4.

[0058] In another preferred implementation of this embodiment, Fig. 9 As shown, at least one through hole is formed through the seal 6 for the heat exchange device to pass through so that the heat exchange device is connected to an external heat source or cold source. The specific number of through holes is determined in combination with the structural form of the heat exchange device.

[0059] In another preferred implementation of this embodiment, Fig. 9 As shown, the sealing member 6 is provided with a first through hole 61 and a second through hole 62. The first through hole 61 allows the flexible heat exchange tube 41 to pass through so that the flexible heat exchange tube 41 is used to pass the heat exchange medium. The second through hole 62 allows the heating wire 42 to pass through so that the heating wire 42 is connected to a power source to supply power and heat the heating wire 42.

[0060] In another preferred implementation of this embodiment, the phase change material 7 is a low melting point alloy (LMPA). Specifically, the low melting point alloy can be Field metal, Wood's alloy or gallium-based alloy, and the melting point of the low melting point alloy is 47 degrees.

[0061] In another preferred implementation of the present embodiment, the low melting point alloy is a bismuth, indium, lead, tin, and cadmium alloy. Specifically, the mass proportions of each element in the low melting point alloy are: bismuth (element symbol is Bi) accounts for 45%, indium (element symbol is In) accounts for 19%, lead (element symbol is Pb) accounts for 23%, tin (element symbol is Sn) accounts for 8%, and cadmium (element symbol is Cd) accounts for 5%.

[0062] In another preferred implementation of this embodiment, the phase change material 7 is a thermoplastic material (TP). During the phase change process, the shape of the thermoplastic material can remain relatively stable. Unlike some inorganic phase change materials, the volume does not expand or shrink too much during the phase change, causing problems such as container rupture. The thermoplastic material also has good fluidity, which facilitates flow in the filling space between the flexible inner tube and the flexible outer surface.

[0063] Embodiment 2

[0064] The present embodiment also provides a variable stiffness module for a continuum robot, comprising the variable stiffness tube and a stiffness conversion control mechanism in the first embodiment, wherein the stiffness conversion control mechanism is connected to a heat exchange device, and the stiffness conversion control mechanism is used to control the heat exchange device, and a surgical tool is connected to the end of the variable stiffness tube, or a surgical tool is transported inside a variable stiffness flexible inner tube. The doctor controls the change in stiffness of the variable stiffness tube through the control mechanism, and provides heat to the phase change material through the heat exchange device, so that the phase change material is heated up and changes from a solid phase to a liquid phase. The variable stiffness tube can bend freely, and cooperate with the motion control module of the continuum robot to move to a target position, and pass through the tube. It can become softer when passing through narrow channels and better adapt to the complex curved pipes and cavity structures inside the human body, such as blood vessels and intestines, so that it can reach the surgical site more smoothly, reduce damage to surrounding tissues, and improve the safety of the operation. After confirming that the surgical tools have reached the surgical site through imaging means, the heat of the phase change material is absorbed by the human body temperature or the heat exchange device, so that the phase change material is cooled and changed from liquid phase to solid phase. The solid phase change material in the hollow groove of the flexible tube is used to increase the stiffness of the variable stiffness tube, and the force is transmitted through the variable stiffness tube and applied to the surgical tool to enable the surgical tool to complete the prescribed action.

[0065] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A variable stiffness tube, characterized in that: It comprises a flexible inner tube and a flexible outer tube sleeved outside the flexible inner tube, a filling space with closed ends is formed between the flexible inner tube and the flexible outer tube, a phase change material and a flexible heat exchange device are arranged in the filling space, the heat exchange device can exchange heat with the phase change material and change the phase change material from a solid phase to a liquid phase, a flexible tube is also arranged in the filling space, a plurality of hollow groove groups are opened through the tube wall of the flexible tube, the hollow groove group comprises at least one hollow groove, the hollow groove is filled with the phase change material, when the phase change material is in a liquid phase, the phase change material can flow freely, and the flexible tube can bend freely.

2. The variable stiffness tube according to claim 1, characterized in that: The heat exchange device can also exchange heat with the phase change material to change the phase change material from a liquid phase to a solid phase.

3. The variable stiffness tube according to claim 1, characterized in that: The hollow grooves in the hollow groove group are arranged along the circumference of the flexible tube, and the hollow grooves extend along the circumferential direction of the flexible tube. The sum of the circumferences of the hollow grooves in the hollow groove group is smaller than the circumference of the flexible tube. The hollow grooves in a plurality of hollow groove groups are staggered axially on the flexible tube, and along the axial direction, the projections of all the hollow grooves in any adjacent hollow groove groups on the cross section of the flexible tube completely cover the cross section.

4. The variable stiffness tube according to claim 1, characterized in that: The heat exchange device comprises a flexible heat exchange tube, in which a heat exchange medium flows to exchange heat with the phase change material.

5. The variable stiffness tube according to claim 4, characterized in that: The flexible heat exchange tube has one, and the flexible heat exchange tube is spirally and seamlessly wound outside the flexible inner tube.

6. The variable stiffness tube according to claim 4, characterized in that: There are a plurality of flexible heat exchange tubes, each of which is alternately spirally wound at a certain angle, and each of which is wound outside the flexible inner tube.

7. The variable stiffness tube according to claim 1 or 4, characterized in that: The heat exchange device comprises a heating wire, which is spirally wound outside the flexible tube and is used to connect to a power source and heat the phase change material.

8. The variable stiffness tube according to claim 1, characterized in that: It also includes a seal, two of which are arranged at both ends of the flexible inner tube and the flexible outer tube, and the seal can fit the outer wall of the flexible inner tube and the inner wall of the flexible outer tube to seal the two ends of the filling space.

9. The variable stiffness tube according to claim 1, characterized in that: The phase change material is a low melting point alloy.

10. A variable stiffness module for a continuum robot, characterized in that: It comprises the variable stiffness tube and the stiffness conversion control mechanism according to any one of claims 1 to 9, wherein the stiffness conversion control mechanism is connected to the heat exchange device, and the stiffness conversion control mechanism is used to control the heat exchange device.

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