Stiffness varying tube and continuum robot stiffness varying module

Abstract

The application discloses a variable stiffness pipe and a continuum robot variable stiffness module, and relates to the technical field of continuum robots. The variable stiffness pipe comprises a flexible inner pipe and a flexible outer pipe sleeved outside the flexible inner pipe. 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 change the phase change material from solid to liquid. A flexible pipe is further arranged in a filling space. A plurality of hollow groove groups are formed through the pipe wall of the flexible pipe. The hollow grooves are filled with the phase change material. When the phase change material is in liquid phase, the flexible pipe can be freely bent. When the phase change material is in solid phase, the shear modulus resisting shear deformation under shear stress is converted into the compression modulus resisting compression deformation under compression stress, so that the rigidity of the variable stiffness pipe can be improved. The variable stiffness continuum robot comprises the variable stiffness pipe and a control mechanism. The rigidity of the variable stiffness pipe is changed to move to a target position and control a surgical tool in cooperation with a motion control module.

Description

Technical Field

[0001] This invention relates to the field of continuous robot technology, and in particular to a variable stiffness tube and a variable stiffness module for continuous robots. Background Technology

[0002] Stiffness refers to a material's ability to resist deformation. Variable stiffness pipe is a type of pipe whose stiffness can change. This type of pipe can change its stiffness characteristics according to changes in 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 robot technology, 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 continuum robot needs to be in a low-stiffness state to minimize 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 force and ensure motion accuracy to reduce trauma. Therefore, variable stiffness tubes have been widely used in the field of continuum robot technology. Existing variable stiffness tubes are usually filled with phase change material in the inner cavity of the tube body. By making the phase change material solid, the variable stiffness tube is stiffened. 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 compressive modulus, the stiffness of the tube body is low under the action of shear force, and the tube body will undergo large deformation. Summary of the Invention

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

[0004] To achieve the above objectives, the present invention provides the following solution:

[0005] This invention provides a variable stiffness tube, comprising a flexible inner tube and a flexible outer tube sleeved outside the flexible inner tube. A closed-end filling space is formed between the flexible inner tube and the flexible outer tube. A phase change material and a flexible heat exchange device are disposed within the filling space. The heat exchange device can exchange heat with the phase change material and cause the phase change material to change from a solid phase to a liquid phase. The flexible tube is also disposed within the filling space. Multiple hollow grooves are formed through the tube wall of the flexible tube. Each hollow groove group includes at least one hollow groove. The hollow grooves are filled with the phase change material. When the phase change material is in a liquid phase, it can flow freely, and the flexible tube can bend freely.

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

[0007] Preferably, each hollow groove in the hollow groove group is arranged circumferentially along the flexible tube, and each hollow groove extends along the circumferential direction of the flexible tube. The sum of the circumferences of each hollow groove in the hollow groove group is less than the circumference of the flexible tube. The hollow grooves in the multiple hollow groove groups are staggered along the axial direction on the flexible tube, and along the axial direction, the projections of all hollow grooves in any adjacent hollow groove group onto the cross-section of the flexible tube completely cover the cross-section.

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

[0009] Preferably, there is one flexible heat exchange tube, which is spirally and seamlessly wound around the outside of the flexible inner tube.

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

[0011] Preferably, the heat exchange device includes a heating wire spirally wound around the flexible tube, the heating wire being used to connect to a power source and heat the phase change material.

[0012] Preferably, it also includes sealing elements, two of which are disposed at both ends of the flexible inner tube and the flexible outer tube. The sealing elements are able to fit against the outer wall of the flexible inner tube and the inner wall of the flexible outer tube to seal both 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 of the preceding claims and a control mechanism, wherein the control mechanism is connected to the heat exchange device and is used to control the heat exchange device.

[0015] The present invention achieves the following technical effects compared to the prior art:

[0016] This invention provides a variable stiffness tube. A heat exchange device installed 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 hollow groove is filled with the phase change material. When the phase change material is cooled to a solid phase, the flexible tube bends in the direction of the shear force under the action of shear force. The distance between the sidewalls on both sides of the hollow groove of the flexible tube becomes smaller. The sidewalls of the flexible tube on both sides of the hollow groove will exert a squeezing 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. Thus, the shear modulus of the flexible tube resisting shear deformation under shear stress is converted into the compressive modulus of the phase change material in the hollow groove resisting compressive deformation under compressive stress, thereby improving the stiffness of the variable stiffness tube.

[0017] This invention also provides a variable stiffness module for a continuum robot. The surgeon controls the stiffness of the variable stiffness tube via a control mechanism, and provides heat to the phase change material (PCM) through a heat exchanger, causing the PCM to heat up and change from a solid phase to a liquid phase. The variable stiffness tube can bend freely and, in conjunction with the motion control module of the continuum robot, moves towards the target position. It becomes more flexible when passing through narrow channels, better adapting to the complex curved tubes and cavities within the human body, such as blood vessels and intestines, thus facilitating smoother access to the surgical site, reducing damage to surrounding tissues, and improving surgical safety. After confirming the surgical instruments have reached the surgical site using imaging techniques, the heat from the PCM is absorbed by the body temperature or the heat exchanger, causing the PCM to cool and change from a liquid phase to a solid phase. The solid PCM within the hollow groove of the flexible tube increases the stiffness of the variable stiffness tube, and the force is transmitted through the variable stiffness tube and applied to the surgical instruments to enable them to perform the prescribed movements. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is an exploded schematic diagram of a variable stiffness tube structure in one implementation method;

[0020] Figure 2 This is a cross-sectional view of a variable stiffness tube structure in one embodiment.

[0021] Figure 3 This is a schematic diagram of a nested structure of a flexible heat exchange tube, a flexible tube, and a heating wire in one embodiment.

[0022] Figure 4 This is a schematic diagram of a flexible tube structure in one embodiment;

[0023] Figure 5 This is a front view of a flexible tube structure in one embodiment;

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

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

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

[0027] Figure 9 This is a schematic diagram of the sealing element 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-Heating wire; 5-Flexible tube; 51-Hollow groove assembly; 6-Sealing element; 61-First through hole; 62-Second through hole; 7-Phase change material. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

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

[0031] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] Example 1

[0033] This embodiment provides a variable stiffness tube, such as Figures 1-9As shown, the system includes a flexible inner tube 1 and a flexible outer tube 2 sleeved outside the flexible inner tube 1. A closed-end filling space 3 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 disposed within the filling space 3. The heat exchange device 4 can exchange heat with the phase change material 7 and cause the phase change material 7 to change from a solid phase to a liquid phase. A flexible tube 5 is also disposed within the filling space 3. Multiple hollow groove groups 51 are formed through the tube wall of the flexible tube 5. Each hollow groove group 51 includes at least one hollow groove 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 a solid phase, the flexible tube 5 will bend in the direction of the shear force under the action of shear force. The distance 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 exert a squeezing effect on 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. Thus, the shear modulus of the flexible tube 5 resisting shear deformation under shear stress is converted into the compressive modulus of the phase change material in the hollow groove resisting compressive deformation under compressive stress, thereby improving the stiffness of the variable stiffness tube.

[0034] In another preferred embodiment of this invention, the flexible tube 5 is made of stainless steel. Stainless steel has high strength and can withstand large forces. It also has good plasticity and toughness. Stainless steel can be manufactured and shaped through various processing techniques, such as forging, rolling, extrusion, stretching, stamping, welding, and cutting, which can meet the production requirements of products with different shapes, sizes, and precision. Stainless steel itself is non-toxic and harmless, does not release harmful substances, and is not harmful to human health or the environment. It is widely used in the field of medical device technology.

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

[0036] In another preferred embodiment of this example, the heat exchange device 4 can also exchange heat with the phase change material 7 to change the phase change material 7 from a liquid phase to a solid phase, thereby improving the efficiency of the phase change material 7 changing from a liquid phase to a solid phase, so that the phase change material 7 can quickly gain rigidity to withstand the force.

[0037] In another preferred embodiment of this example, such as Figures 4-6As shown, the hollow grooves in the hollow groove group 51 are arranged circumferentially along the flexible tube 5, and each hollow groove extends along the circumferential direction of the flexible tube 5. 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. The hollow grooves in the multiple hollow groove groups are staggered circumferentially on the flexible tube to reduce the bending stiffness of the flexible tube on the cross section where the hollow grooves are located. In the axial direction, the projections of all 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 the liquid phase.

[0038] In another preferred embodiment of this example, such as Figures 4-6 As shown, the width of the hollow grooves along the axial direction of the flexible tube 5 should be as narrow as possible, preferably 0.1 to 0.5 mm. The density of the hollow grooves should be as high as possible, and the spacing between adjacent hollow grooves is preferably 0.1 to 0.5 mm. By reducing the width and spacing of the hollow grooves along the axial direction, the hollow grooves are densely distributed on the sidewall of the flexible tube, reducing the restriction of the flexible tube sidewall on the flexible tube when bending, thereby increasing 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. 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 ending end of the hollow groove to the axis of the flexible tube 5 is preferably 140° to 175°. By increasing the angle of the hollow grooves, 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 the liquid phase. The axes of symmetry of any two adjacent hollow groove groups are orthogonal to avoid inconsistent bending stiffness of the flexible tube in each direction. Through the above arrangement, the variable stiffness tube has sufficient flexibility when the phase change material 7 is in the liquid phase.

[0039] In another preferred embodiment of this example, the hollow groove group 51 can be processed by wire cutting on the flexible tube 5. A continuously moving fine metal wire is used as a tool electrode to perform pulse spark discharge to erode the tube wall of the rigid support hanger, thereby achieving high-precision cutting and shaping.

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

[0041] In another preferred embodiment of this example, such as 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 provides heat to the phase change material. As heat is continuously input, the temperature of the phase change material 7 gradually increases. Once the specific melting point of the phase change material 7 is reached, the phase change material 7 begins to change from a solid to a liquid state. When the liquid phase change material 7 is cooled, the heat exchange medium absorbs the heat from the phase change material. The heat is gradually transferred from the phase change material 7 to the flexible heat exchange tube 41. As the temperature of the phase change material 7 continuously decreases, when its freezing point is reached, the phase change material 7 changes from a liquid to a solid state.

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

[0043] In another preferred embodiment of this example, the flexible inner tube 1 and the flexible outer tube 2 are made of polydimethylsiloxane (PDMS) or silicone, and are coated with a heat-insulating coating to give the tube wall strong heat insulation ability, which can avoid damage to human tissues by the variable stiffness tube when the heat exchange medium is introduced.

[0044] In another preferred embodiment of this example, such as Figure 7 As shown, there is one flexible heat exchange tube 41, which is spirally and seamlessly wound around the outside of the flexible inner tube 1. By seamlessly winding the flexible heat exchange tube 41 around 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 embodiment of this example, such as Figure 8 As shown, there are multiple flexible heat exchange tubes 41, preferably two. The multiple flexible heat exchange tubes 41 are arranged in parallel around the flexible inner tube 1. By setting multiple flexible heat exchange tubes 41, the contact area between each flexible heat exchange tube 41 and the phase change material 7 is reduced, the flow rate of the heat exchange medium is increased, and each flexible heat exchange tube 41 can exchange heat with the phase change material 7 within the contact range at the same time, 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 embodiment of this example, 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. Each flexible heat exchange tube can exchange heat with the phase change material simultaneously, thereby improving the heat exchange efficiency between the flexible heat exchange tube and the phase change material.

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

[0048] In another preferred embodiment of this example, there are multiple flexible heat exchange tubes 41, and each flexible heat exchange tube is intertwined with each other at a certain angle to form a braided network. The braided network is wrapped around the outside of the flexible inner tube to exchange heat with the phase change material.

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

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

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

[0052] In another preferred embodiment of this example, such as Figure 3 As shown, the heat exchange device 4 includes a heating wire 42, which is spirally wound around the flexible tube 5. The heating wire 42 is used to connect to the power supply 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 embodiment of this example, 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 the power supply 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 embodiment of this example, such as Figure 3 As shown, the flexible heat exchange tube 41 is spirally and seamlessly wound around the outside of the flexible inner tube, and is used to exchange heat with the phase change material 7 between the flexible inner tube 1 and the flexible tube 5. The heating wire 42 is wound around the outside of the flexible tube 5, and is used to exchange heat with the phase change material 7 between the flexible tube 5 and the flexible outer tube 2. In summary, heat exchange devices 4 are provided on both the inner and outer sides of the flexible tube 5 to improve the heat exchange efficiency between the heat exchange devices 4 and the phase change material 7.

[0055] In another preferred embodiment of this invention, 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 preferred embodiment of this invention, the heat exchange device 4 includes an optical fiber with a grating on it. The optical fiber is positioned between a flexible inner tube and a flexible outer tube. Light propagates in the optical fiber and is guided through the grating to the phase change material, so that the optical fiber and the phase change material exchange heat. Based on the thermal motion of microscopic particles (such as atoms and molecules) inside the optical fiber material, heat is transferred from a higher temperature region to a lower temperature region through mutual collisions.

[0057] In another preferred embodiment of this example, such as Figure 9 As shown, the variable stiffness tube also includes a sealing element 6, which is disposed at both ends of the flexible inner tube 1 and the flexible outer tube 2. The sealing element 6 can fit against the outer wall and the inner wall of the flexible inner tube to seal the filling space 3 between the flexible inner tube 1 and the flexible outer tube 2, 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 embodiment of this example, such as Figure 9 As shown, at least one through hole is provided on the sealing element 6 to allow the heat exchange device to pass through, so that the heat exchange device can be connected to an external heat source or cold source. The specific number of through holes is determined in conjunction with the structural form of the heat exchange device.

[0059] In another preferred embodiment of this example, such as Figure 9 As shown, the sealing member 6 has 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 can be used to pass 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 the power source for heating.

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

[0061] In another preferred embodiment of this example, the low-melting-point alloy is a bismuth-indium-lead-tin-cadmium alloy. Specifically, the mass percentages of each element in the low-melting-point alloy are as follows: bismuth (symbol: Bi) 45%, indium (symbol: In) 19%, lead (symbol: Pb) 23%, tin (symbol: Sn) 8%, and cadmium (symbol: Cd) 5%.

[0062] In another preferred embodiment of this example, the phase change material 7 is a thermoplastic material (TP). During the phase change process, the thermoplastic material can maintain a relatively stable shape and will not cause problems such as excessive volume expansion or contraction during the phase change, which may lead to container rupture, as some inorganic phase change materials do. The thermoplastic material also has good fluidity, which makes it easy to flow in the filling space between the flexible inner tube and the flexible outer tube.

[0063] Example 2

[0064] This embodiment also provides a variable stiffness module for a continuum robot, including the variable stiffness tube and stiffness conversion control mechanism as described in Embodiment 1. The stiffness conversion control mechanism is connected to a heat exchange device and is used to control the heat exchange device. Surgical tools are connected to the end of the variable stiffness tube or transported inside the variable stiffness flexible inner tube. The surgeon 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, causing the phase change material to heat up and change from a solid phase to a liquid phase. The variable stiffness tube can bend freely and move towards the target position in conjunction with the motion control module of the continuum robot. When passing through narrow passages, it can become more flexible, better adapting to the complex curved tubes and cavities inside the human body, such as blood vessels and intestines, thus reaching the surgical site more smoothly, reducing damage to surrounding tissues, and improving the safety of the surgery. After confirming that the surgical instrument has reached the surgical site through imaging methods, the phase change material absorbs heat through the body temperature or a heat exchange device, causing the phase change material to cool and change from a liquid phase to a solid phase. The phase change material in the hollow groove of the flexible tube is in a solid phase to increase the stiffness of the variable stiffness tube. The force is transmitted through the variable stiffness tube and applied to the surgical instrument so that the surgical instrument can complete the prescribed action.

[0065] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A variable stiffness tube, characterized in that: The system includes a flexible inner tube and a flexible outer tube sleeved around the inner tube. A sealed space is formed between the inner and outer tubes. A phase change material and a flexible heat exchanger are disposed within this space. The heat exchanger exchanges heat with the phase change material, causing it to change from a solid to a liquid phase. A flexible tube, made of stainless steel, is also disposed within the space. Multiple hollow grooves are formed through the wall of the flexible tube, each groove including at least one hollow groove. The hollow groove is filled with the phase change material using wire cutting. When the phase change material is in a liquid phase, it can flow freely. The flexible tube can be bent freely. The heat exchange device includes a flexible heat exchange tube, which is spirally and seamlessly wound around the outside of the flexible inner tube for heat exchange with the phase change material between the flexible inner tube and the flexible tube. The heat exchange device also includes a heating wire, which is wound around the outside of the flexible tube for heat exchange with the phase change material between the flexible tube and the flexible outer tube.

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, causing the phase change material to change 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 circumferentially along the flexible tube, and each hollow groove extends along the circumferential direction of the flexible tube. The sum of the circumferences of the hollow grooves in the hollow groove group is less than the circumference of the flexible tube. The hollow grooves in the multiple hollow groove groups are staggered along the axial direction on the flexible tube, and along the axial direction, the projections of all the hollow grooves in any adjacent hollow groove group onto 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 flexible heat exchange tube contains a heat exchange medium that flows inside to exchange heat with the phase change material.

5. The variable stiffness tube according to claim 4, characterized in that, There is one flexible heat exchange tube.

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

7. The variable stiffness tube according to any one of claims 1 or 4, characterized in that, The heat exchange device includes a heating wire, which is spirally wound around the outside of the flexible tube. The heating wire 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 sealing elements, two of which are disposed at both ends of the flexible inner tube and the flexible outer tube. The sealing elements are able to fit against the outer wall of the flexible inner tube and the inner wall of the flexible outer tube to seal both 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, The device includes a variable stiffness tube and a stiffness conversion control mechanism as described in any one of claims 1 to 9, wherein the stiffness conversion control mechanism is connected to the heat exchange device and is used to control the heat exchange device.

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