A stiffness adjusting device, a flexible continuum manipulator with adjustable stiffness, and a stiffness adjusting method

Abstract

The present application relates to a kind of rigidity adjusting device, stiffness-adjustable flexible continuum manipulator and rigidity adjusting method, it solves how to improve the load capacity of flexible continuum manipulator, existing flexible continuum manipulator with variable stiffness capacity is not suitable for the technical problem of solar wing auxiliary unlocking scene in vacuum environment, it includes spiral body, first driving rod, second driving rod, third driving rod and three groups of channels, three groups of channels are all made of a plurality of friction rings fixed on the periphery of spiral body, first driving rod passes through each friction ring of first group of channels, second driving rod passes through each friction ring of second group of channels, and third driving rod passes through each friction ring of third group of channels.

Description

Technical Field

[0001] This invention relates to the field of flexible continuous robotic arm technology, and more specifically, to a stiffness adjustment device, a stiffness-adjustable flexible continuous robotic arm, and a stiffness adjustment method. Background Technology

[0002] Flexible continuum robotic arms are characterized by high compliance and flexibility, with telescopic flexible continuum robotic arms exhibiting even greater flexibility. Currently, research on telescopic flexible continuum robotic arms is limited both domestically and internationally. The Burgner-Kahrs research group at the University of Toronto has pioneered two types of telescopic flexible continuum robotic arms: a central rod structure utilizing permanent magnet force to provide tension, and a paper-folding structure utilizing air pressure to provide tension. The research results show that telescopic motion significantly improves the flexibility of the flexible continuum robotic arm. The research challenge of telescopic flexible continuum robotic arms lies in how to provide elongation "tension" in a flexible manner, opposite to the contraction of the robotic arm, to maintain shape stability during deformation.

[0003] The high compliance of flexible continuous robotic arms results in a low load capacity, which limits their application in certain scenarios.

[0004] To enhance the load-bearing capacity of flexible continuum manipulators and enable their application in specific scenarios (such as on-orbit assisted unlocking of solar arrays), it is essential to endow them with variable stiffness capabilities. During long-term on-orbit operation, satellites primarily rely on solar arrays for power. The flexible continuum manipulator drives the end effector to perform unlocking operations on the solar arrays, thereby deploying them. This process requires adjusting stiffness to increase load-bearing capacity.

[0005] In existing technologies, variable stiffness methods mainly fall into four categories: blocking, phase change, antagonism, and variable structure.

[0006] The principle of variable stiffness blocking is to change the overall stiffness by altering the friction between a large number of ordered, identical micro-units. Variable stiffness blocking mainly includes three methods: particle blocking, fiber blocking, and layer blocking. For particle blocking, please refer to the invention patent application with publication number CN114516070A. Methods for changing friction include vacuum negative pressure and electrostatic adsorption. Variable stiffness blocking has the advantages of real-time and continuous operation, but it performs poorly in terms of repeatability and structural compactness. The vacuum negative pressure method required for blocking is unsuitable for the vacuum environment of a track, and the electrostatic adsorption method does not meet the requirements for engineering reliability. Furthermore, because the total volume of the blocking unit is constant, its allowable expansion and contraction is very small, thus it cannot improve the flexibility of the flexible continuous body manipulator and is not very suitable for telescopic flexible continuous body manipulators.

[0007] Phase change stiffness adjustment utilizes the change in modulus of a phase change material (solid-liquid or solid-solid phase transition) to adjust the stiffness of a robotic arm. For example, the solid-liquid phase transition of low-melting-point alloys can achieve large-scale stiffness control, while the glass-rubber phase transition of materials such as shape memory polymers (SMPs) can achieve continuous, large-scale stiffness adjustment. However, the E-parameter of low-melting-point alloys and SMPs... 3 / ρ (this index measures the contribution of a unit mass of material to the bending stiffness of a structure, where E is the Young's modulus of the material and ρ is the density of the material) is lower than that of commonly used metals such as steel and aluminum, and does not have a high modulus-density ratio, so it is not suitable for lightweight long arms.

[0008] The basic principle of antagonistic variable stiffness is to increase the number of actuating degrees of freedom compared to the system's motion degrees of freedom, creating overconstraint and thus increasing the system's stiffness. Antagonistic variable stiffness for flexible robotic arms is typically achieved pneumatically because gas expansion can generate the tension required for antagonism, while other flexible actuations are less likely to generate significant tension. See the invention patent application CN117207165A for reference. Antagonistic variable stiffness allows for continuous and stable stiffness adjustment and exhibits good passive compliance; however, the required pneumatic method is not suitable for operation in an on-orbit vacuum environment.

[0009] It is evident that existing flexible continuum robotic arms with variable stiffness capabilities are not suitable for on-orbit assisted unlocking scenarios of solar arrays, and the variable stiffness methods are not ideal. Summary of the Invention

[0010] This invention aims to address the technical problem of how to improve the load capacity of flexible continuous robotic arms, and the fact that existing flexible continuous robotic arms with variable stiffness capabilities are not suitable for on-orbit assisted unlocking scenarios of solar arrays in vacuum environments. The invention provides a stiffness adjustment device with a variable stiffness structure, a flexible continuous robotic arm with adjustable stiffness, and a stiffness adjustment method.

[0011] This invention provides a stiffness adjustment device, including a drive rod and a friction ring. The friction ring has an elliptical hole, and the cross-section of the drive rod is elliptical. The drive rod passes through the elliptical hole of the friction ring. When the drive rod and the elliptical hole of the friction ring are matched and engaged, after the drive rod rotates at a certain angle, the drive rod and the elliptical hole of the friction ring are pressed together to generate friction, thereby locking the drive rod.

[0012] The present invention also provides a stiffness adjustment method using a stiffness adjustment device, comprising the following steps:

[0013] Make the drive rod match and fit the elliptical hole of the friction ring;

[0014] The drive rod is rotated at a certain angle, which causes the drive rod to be pressed against the elliptical hole of the friction ring to generate friction.

[0015] The present invention also provides a flexible continuous robotic arm with adjustable stiffness, comprising a helical body, a first drive rod, a second drive rod, a third drive rod, and three sets of channels. The first set of channels consists of several friction rings fixed to the periphery of the helical body, the second set of channels consists of several friction rings fixed to the periphery of the helical body, and the third set of channels consists of several friction rings fixed to the periphery of the helical body. The friction rings in the first set of channels are distributed along the length direction of the helical body, the friction rings in the second set of channels are distributed along the length direction of the helical body, and the friction rings in the third set of channels are distributed along the length direction of the helical body; the three sets of channels are evenly distributed in the radial circumferential direction.

[0016] The first drive rod passes through each friction ring of the first set of channels, and the end of the first drive rod is positioned at the front end of the spiral body; the second drive rod passes through each friction ring of the second set of channels, and the end of the second drive rod is positioned at the front end of the spiral body; the third drive rod passes through each friction ring of the third set of channels, and the end of the third drive rod is positioned at the front end of the spiral body.

[0017] The friction ring has an elliptical hole, and the cross-section of the first drive rod is elliptical. The first drive rod passes through the elliptical hole of the corresponding friction ring. When the first drive rod matches the elliptical hole of the corresponding friction ring, the first drive rod can move along the elliptical hole of the corresponding friction ring. When the first drive rod rotates a certain angle while matching the elliptical hole of the corresponding friction ring, the first drive rod is squeezed against the elliptical hole of the corresponding friction ring to generate friction, thereby locking the first drive rod.

[0018] The cross-section of the second drive rod is elliptical. The second drive rod passes through the elliptical hole of the corresponding friction ring. When the second drive rod matches the elliptical hole of the corresponding friction ring, the second drive rod can move along the elliptical hole of the corresponding friction ring. When the second drive rod rotates a certain angle while matching the elliptical hole of the corresponding friction ring, the second drive rod is squeezed against the elliptical hole of the corresponding friction ring to generate friction, thereby locking the second drive rod.

[0019] The cross-section of the third drive rod is elliptical. The third drive rod passes through the elliptical hole of the corresponding friction ring. When the third drive rod matches the elliptical hole of the corresponding friction ring, the third drive rod can move along the elliptical hole of the corresponding friction ring. When the third drive rod rotates a certain angle while matching the elliptical hole of the corresponding friction ring, the third drive rod is squeezed against the elliptical hole of the corresponding friction ring to generate friction, thereby locking the third drive rod.

[0020] Preferably, the first drive rod is made of photosensitive resin material, the second drive rod is made of photosensitive resin material, and the third drive rod is made of photosensitive resin material.

[0021] Preferably, the drive rod is a flexible shaft.

[0022] Preferably, the drive rod is a flexible steel wire shaft.

[0023] Preferably, the friction ring is made of rubber.

[0024] The present invention also provides a method for adjusting the stiffness of a flexible continuum robotic arm with adjustable stiffness, comprising the following steps:

[0025] When the first drive rod, the second drive rod, and / or the third drive rod rotate a certain angle while matching the elliptical hole of the corresponding friction ring, the drive rod and the elliptical hole of the friction ring are pressed together to generate friction.

[0026] The present invention also provides a flexible continuous robotic arm system with adjustable stiffness, including a drive device, a helical body, a first drive rod, a second drive rod, a third drive rod, and three sets of channels. The first set of channels consists of several friction rings fixed to the periphery of the helical body, the second set of channels consists of several friction rings fixed to the periphery of the helical body, and the third set of channels consists of several friction rings fixed to the periphery of the helical body. The friction rings in the first set of channels are distributed along the length direction of the helical body, the friction rings in the second set of channels are distributed along the length direction of the helical body, and the friction rings in the third set of channels are distributed along the length direction of the helical body; the three sets of channels are evenly distributed in the radial circumferential direction.

[0027] The first drive rod passes through each friction ring of the first set of channels, and the end of the first drive rod is positioned at the front end of the spiral body; the second drive rod passes through each friction ring of the second set of channels, and the end of the second drive rod is positioned at the front end of the spiral body; the third drive rod passes through each friction ring of the third set of channels, and the end of the third drive rod is positioned at the front end of the spiral body.

[0028] The friction ring has an elliptical hole, and the cross-section of the first drive rod is elliptical. The first drive rod passes through the elliptical hole of the corresponding friction ring. When the first drive rod matches the elliptical hole of the corresponding friction ring, the first drive rod can move along the elliptical hole of the corresponding friction ring. When the first drive rod rotates a certain angle while matching the elliptical hole of the corresponding friction ring, the first drive rod is squeezed against the elliptical hole of the corresponding friction ring to generate friction, thereby locking the first drive rod.

[0029] The cross-section of the second drive rod is elliptical. The second drive rod passes through the elliptical hole of the corresponding friction ring. When the second drive rod matches the elliptical hole of the corresponding friction ring, the second drive rod can move along the elliptical hole of the corresponding friction ring. When the second drive rod rotates a certain angle while matching the elliptical hole of the corresponding friction ring, the second drive rod is squeezed against the elliptical hole of the corresponding friction ring to generate friction, thereby locking the second drive rod.

[0030] The cross-section of the third drive rod is elliptical. The third drive rod passes through the elliptical hole of the corresponding friction ring. When the third drive rod matches the elliptical hole of the corresponding friction ring, the third drive rod can move along the elliptical hole of the corresponding friction ring. When the third drive rod rotates a certain angle while matching the elliptical hole of the corresponding friction ring, the third drive rod is squeezed against the elliptical hole of the corresponding friction ring to generate friction, thereby locking the third drive rod.

[0031] The drive unit is used to drive the first drive rod, the second drive rod, and the third drive rod to move, thereby causing the spiral body to bend, contract, extend, and change stiffness.

[0032] Preferably, the driving device includes three driving mechanisms, each including a guide cylinder, a rotating shaft, a winding disc, a linear translation drive gear, a rotation drive gear, a first motor, and a second motor. The rear of the rotating shaft is located in the guide cylinder, allowing it to slide within the cylinder. The rotating shaft has several spur gear sections, each located radially on the rotating shaft. These spur gear sections are arranged side-by-side along the length of the rotating shaft. The winding disc is connected to the front end of the rotating shaft. The linear translation drive gear meshes with the spur gear section at the front of the rotating shaft, with its axis perpendicular to the axis of the rotating shaft. The rotation drive gear meshes with the spur gear section at the front of the rotating shaft, with its axis parallel to the axis of the rotating shaft. The first motor drives the linear translation drive gear to rotate, and the second motor drives the rotation drive gear to rotate.

[0033] The rear ends of the first, second, and third drive rods are respectively connected to the winding discs in the three drive mechanisms.

[0034] The beneficial effects of this invention are: it actively adjusts the overall stiffness of the flexible continuous manipulator, thereby improving the load-bearing capacity of the flexible continuous manipulator, and is particularly suitable for telescopic flexible continuous manipulators.

[0035] The structure achieves variable stiffness through mechanical movement, independent of external conditions such as air pressure. This enables lightweight robotic arms as well as long-arm robotic arms.

[0036] This expands the application scenarios of flexible continuous robotic arms and improves their performance.

[0037] This invention has a wide range of applications, not limited to solving the problem of on-orbit assisted unlocking of solar arrays, but also applicable to other technical fields such as minimally invasive surgery.

[0038] Further features and aspects of the present invention will be clearly described in the following detailed description with reference to the accompanying drawings. Attached Figure Description

[0039] Figure 1This is a schematic diagram of the structure of the flexible continuum robotic arm of the present invention;

[0040] Figure 2 yes Figure 1 A structural diagram of a portion of the structure shown;

[0041] Figure 3 This is a schematic diagram showing the drive rod located in the elliptical hole of the friction ring in the structure of a flexible continuous robotic arm.

[0042] Figure 4 This is a schematic diagram showing the first drive rod located in the elliptical hole of the friction ring;

[0043] Figure 5 yes Figure 4 A schematic diagram showing the state after rotating counterclockwise by 30° from the state shown.

[0044] Figure 6 yes Figure 4 A schematic diagram showing the state after rotating 90° counterclockwise from the state shown.

[0045] Figure 7 This is a schematic diagram of the drive unit;

[0046] Figure 8 yes Figure 7 A schematic diagram showing the connection relationship between the central rotating shaft, the linear translation drive gear, and the self-rotating drive gear.

[0047] Explanation of symbols in the diagram:

[0048] 1. Helical body, 2. Friction ring, 3. First drive rod, 4. Second drive rod, 5. Third drive rod, 6. Guide cylinder, 7. Rotating shaft, 7-1. Spur gear section, 8. Winding disc, 9. Linear translation drive gear, 10. Rotation drive gear. Detailed Implementation

[0049] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0050] like Figure 1 and 2As shown, the flexible continuous robotic arm includes a helical body 1, a first drive rod 3, a second drive rod 4, a third drive rod 5, and three sets of channels. Each set of channels consists of several friction rings 2 fixedly connected to the periphery of the helical body 1. The friction rings constituting the first set of channels are distributed along the length of the helical body 1, the second set of channels are distributed along the length of the helical body 1, and the third set of channels are distributed along the length of the helical body 1. The three sets of channels are evenly distributed in the radial circumferential direction (that is, the included angle between two adjacent sets of channels is 120°). The first drive rod 3 passes through each friction ring in the first set of channels, and its end is positioned at the front end of the helical body 1. The second drive rod 4 passes through each friction ring in the second set of channels, and its end is positioned at the front end of the helical body 1. The third drive rod 5 passes through each friction ring in the third set of channels, and its end is positioned at the front end of the helical body 1.

[0051] The helical body 1 is a helical structure with a wide range of extension, contraction, and bending deformation capabilities. Under external force, pulling the three drive rods enables omnidirectional bending of the helical body 1. For example, pulling the first drive rod 3 while simultaneously releasing the second drive rod 4 and the third drive rod 5 will cause the helical body 1 to bend towards the first drive rod 3. When the helical body 1 is in a straight state, simultaneously pulling the first drive rod 3, the second drive rod 4, and the third drive rod 5 will cause the helical body 1 to contract, shortening its length. When the helical body 1 is in a contracted state, simultaneously releasing the first drive rod 3, the second drive rod 4, and the third drive rod 5 will cause the helical body 1 to extend, lengthening its length. Therefore, simultaneously operating the three drive rods, moving them along the axis of the helical body 1, enables the extension and contraction of the entire flexible continuous robotic arm. These are common mechanisms and action methods of currently prevalent line-driven soft robotic arms, which will be understood by those skilled in the art.

[0052] refer to Figure 3 and 4 The friction ring 2 has an elliptical hole. The first drive rod 3 has an elliptical cross-section and passes through the elliptical hole in the friction ring 2, matching the elliptical hole. The first drive rod 3 can move along the elliptical hole in the friction ring 2. Similarly, the second drive rod 4 also has an elliptical cross-section and passes through the corresponding elliptical hole in the friction ring, allowing it to move along the elliptical hole. The third drive rod 5 also has an elliptical cross-section and passes through the corresponding elliptical hole in the friction ring, also allowing it to move along the elliptical hole. In this state, operating the three drive rods can drive the entire flexible continuous robotic arm to extend, retract, or bend.

[0053] When the first drive rod 3 rotates a certain angle, refer toFigure 5 For example, when rotated 30°, the first drive rod 3 is pressed against the elliptical hole of the friction ring 2. Friction is generated between the first drive rod 3 and the elliptical hole of the friction ring 2. Under the action of this friction, the first drive rod 3 is locked and cannot move along the elliptical hole of the friction ring 2 (that is, the friction ring 2 cannot move relative to the first drive rod 3). At this time, the first drive rod 3 and the spiral body 1 become a single structure, thus significantly increasing the stiffness of the spiral body 1 and the overall stiffness of the flexible continuous robotic arm. The greater the amount of compression between the first drive rod 3 and the elliptical hole of the friction ring 2, the greater the friction, and consequently, the greater the stiffness of the entire robotic arm. The greater the rotation angle of the first drive rod 3, the greater the corresponding amount of compression. (Refer to...) Figure 6 The compression force and friction are at their maximum when the first drive rod 3 rotates 90° counterclockwise, resulting in the highest stiffness of the entire robotic arm. Therefore, the stiffness of the entire robotic arm is adjustable and can be precisely and continuously adjusted. Figure 6 In this state, the first drive lever 3 continues to rotate counterclockwise by 90° until it reaches... Figure 4 In the state shown, there is no compression between the first drive rod 3 and the elliptical hole of the friction ring 2, the first drive rod 3 is released, and the first drive rod 3 matches and fits the elliptical hole of the friction ring 2.

[0054] The locking and releasing processes of the second drive rod 4 are the same as those of the first drive rod 3, and will not be described again. The locking and releasing processes of the third drive rod 5 are also the same as those of the first drive rod 3, and will not be described again. Rotating just one of the three drive rods changes the locking force, thus adjusting the stiffness of the entire robotic arm. Rotating two drive rods simultaneously also adjusts the stiffness, as does rotating all three. By independently controlling the rotation of each drive rod in different bending directions of the robotic arm, different stiffnesses can be achieved for each direction of bending, exhibiting anisotropic stiffness.

[0055] The drive rod can be made of photosensitive resin. It can also be a flexible steel wire shaft or another type of woven flexible shaft.

[0056] The material of friction ring 2 should preferably be a material with a high coefficient of friction with the drive rod, such as rubber, which can deform under the pressure of the drive rod, thus improving the reliability of friction control.

[0057] The drive mechanism used to actuate the drive lever can be implemented in the following specific structures, such as... Figure 7 and 8As shown, the system includes a guide cylinder 6, a rotating shaft 7, a winding disc 8, a linear translation drive gear 9, a rotation drive gear 10, a first motor, and a second motor. The rear of the rotating shaft 7 is located within the guide cylinder 6, allowing it to slide within the cylinder. The rotating shaft 7 has several spur gear sections 7-1, each located radially on the rotating shaft 7. These spur gear sections 7-1 are arranged side-by-side along the length of the rotating shaft 7. The winding disc 8 is connected to the front end of the rotating shaft 7. The linear translation drive gear 9 meshes with the spur gear section 7-1 at the front of the rotating shaft 7, with its axis perpendicular to the axis of the rotating shaft 7. The rotation drive gear 10 meshes with the spur gear section 7-1 at the front of the rotating shaft 7, with its axis parallel to the axis of the rotating shaft 7. The first motor drives the linear translation drive gear 9 to rotate, and the second motor drives the rotation drive gear 10 to rotate. When the linear translation drive gear 9 rotates, and the rotation drive gear 10 remains stationary, it can drive the rotating shaft 7 to move linearly within the guide cylinder 6, either to the left or right, or forward or backward. When the linear translation drive gear 9 remains stationary, the rotation of the rotation drive gear 10 can cause the rotating shaft 7 to rotate.

[0058] One drive device is matched with one drive rod. For example, the rear end of the first drive rod 3 is connected to the winding disc 8. When the rotating shaft 7 moves to the right, it pulls the first drive rod 3; when the rotating shaft 7 moves to the left, it releases the first drive rod 3. When the rotating shaft 7 rotates, it drives the first drive rod 3 to rotate.

[0059] The flexible continuous robotic arm disclosed in this invention takes into account actual conditions such as relative sway between satellites, large extension of the flexible arm, and joint locking force, and features a locking variable stiffness in its structural design; it is particularly suitable for telescopic flexible robotic arms, is more reliable in engineering, and is suitable for vacuum on-orbit environments.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and variations.

Claims

1. A flexible continuous robotic arm with adjustable stiffness, characterized in that, The device includes a spiral body, a first drive rod, a second drive rod, a third drive rod, and three sets of channels. The three sets of channels are designated as a first set of channels, a second set of channels, and a third set of channels. The first set of channels consists of several friction rings fixed to the periphery of the spiral body. The friction rings in the first set of channels, the second set of channels, and the third set of channels are all distributed along the length of the spiral body. The three sets of channels are evenly distributed in a radial circumferential direction. The first drive rod passes through each friction ring of the first set of channels, and the end of the first drive rod is positioned at the front end of the spiral body; The second drive rod passes through each friction ring of the second set of channels, and the end of the second drive rod is positioned at the front end of the spiral body; the third drive rod passes through each friction ring of the third set of channels, and the end of the third drive rod is positioned at the front end of the spiral body. The friction ring is provided with an elliptical hole, and the cross-section of the first drive rod is elliptical. The first drive rod passes through the elliptical hole of the corresponding friction ring. When the first drive rod matches the elliptical hole of the corresponding friction ring, the first drive rod can move along the elliptical hole of the corresponding friction ring. When the first drive rod rotates a certain angle while matching the elliptical hole of the corresponding friction ring, the first drive rod is squeezed against the elliptical hole of the corresponding friction ring to generate friction, thereby locking the first drive rod. The cross-section of the second drive rod is elliptical. The second drive rod passes through the elliptical hole of the corresponding friction ring. When the second drive rod matches the elliptical hole of the corresponding friction ring, the second drive rod can move along the elliptical hole of the corresponding friction ring. When the second drive rod rotates a certain angle while matching the elliptical hole of the corresponding friction ring, the second drive rod is squeezed against the elliptical hole of the corresponding friction ring to generate friction, thereby locking the second drive rod. The cross-section of the third drive rod is elliptical. The third drive rod passes through the elliptical hole of the corresponding friction ring. When the third drive rod matches the elliptical hole of the corresponding friction ring, the third drive rod can move along the elliptical hole of the corresponding friction ring. When the third drive rod rotates a certain angle while matching the elliptical hole of the corresponding friction ring, the third drive rod is squeezed against the elliptical hole of the corresponding friction ring to generate friction, thereby locking the third drive rod.

2. The stiffness-adjustable flexible continuous robotic arm according to claim 1, characterized in that, The first drive rod is made of photosensitive resin, the second drive rod is made of photosensitive resin, and the third drive rod is made of photosensitive resin.

3. The stiffness-adjustable flexible continuous robotic arm according to claim 1, characterized in that, The drive rod is a flexible shaft.

4. The stiffness-adjustable flexible continuous robotic arm according to claim 3, characterized in that, The drive rod is a flexible steel wire shaft.

5. The stiffness-adjustable flexible continuous robotic arm according to claim 1, characterized in that, The friction ring is made of rubber.

6. A method for adjusting the stiffness of a flexible continuous manipulator with adjustable stiffness as described in claim 1, characterized in that, Includes the following steps: When the first drive rod, the second drive rod, and / or the third drive rod rotate a certain angle while matching the elliptical hole of the corresponding friction ring, the drive rod and the elliptical hole of the friction ring are pressed together to generate friction.

7. A stiffness adjustment device, applied to a stiffness-adjustable flexible continuous robotic arm as described in claim 1, characterized in that, The device includes a drive rod and a friction ring. The friction ring has an elliptical hole, and the cross-section of the drive rod is elliptical. The drive rod passes through the elliptical hole of the friction ring. When the drive rod and the elliptical hole of the friction ring are matched and engaged, after the drive rod rotates at a certain angle, the drive rod and the elliptical hole of the friction ring are squeezed together to generate friction, thereby locking the drive rod.

8. A stiffness adjustment method using the stiffness adjustment device of claim 7, characterized in that, Includes the following steps: Make the drive rod match and fit the elliptical hole of the friction ring; The drive rod is rotated at a certain angle, which causes the drive rod to be pressed against the elliptical hole of the friction ring to generate friction.

9. A flexible continuous robotic arm system with adjustable stiffness, characterized in that, The device includes a drive unit, a spiral body, a first drive rod, a second drive rod, a third drive rod, and three sets of channels. The three sets of channels are designated as a first set of channels, a second set of channels, and a third set of channels. The first set of channels consists of several friction rings fixed to the periphery of the spiral body. The second set of channels also consists of several friction rings fixed to the periphery of the spiral body. The friction rings in the first set of channels, the second set of channels, and the third set of channels are all distributed along the length of the spiral body. The three sets of channels are evenly distributed in the radial circumferential direction. The first drive rod passes through each friction ring of the first set of channels, and the end of the first drive rod is positioned at the front end of the spiral body; The second drive rod passes through each friction ring of the second set of channels, and the end of the second drive rod is positioned at the front end of the spiral body; the third drive rod passes through each friction ring of the third set of channels, and the end of the third drive rod is positioned at the front end of the spiral body. The friction ring is provided with an elliptical hole, and the cross-section of the first drive rod is elliptical. The first drive rod passes through the elliptical hole of the corresponding friction ring. When the first drive rod matches the elliptical hole of the corresponding friction ring, the first drive rod can move along the elliptical hole of the corresponding friction ring. When the first drive rod rotates a certain angle while matching the elliptical hole of the corresponding friction ring, the first drive rod is squeezed against the elliptical hole of the corresponding friction ring to generate friction, thereby locking the first drive rod. The cross-section of the second drive rod is elliptical. The second drive rod passes through the elliptical hole of the corresponding friction ring. When the second drive rod matches the elliptical hole of the corresponding friction ring, the second drive rod can move along the elliptical hole of the corresponding friction ring. When the second drive rod rotates a certain angle while matching the elliptical hole of the corresponding friction ring, the second drive rod is squeezed against the elliptical hole of the corresponding friction ring to generate friction, thereby locking the second drive rod. The cross-section of the third drive rod is elliptical. The third drive rod passes through the elliptical hole of the corresponding friction ring. When the third drive rod matches the elliptical hole of the corresponding friction ring, the third drive rod can move along the elliptical hole of the corresponding friction ring. When the third drive rod rotates a certain angle while matching the elliptical hole of the corresponding friction ring, the third drive rod is squeezed against the elliptical hole of the corresponding friction ring to generate friction, thereby locking the third drive rod. The driving device is used to drive the first driving rod, the second driving rod, and the third driving rod to move, thereby causing the spiral body to bend, contract, extend, and change stiffness.

10. The stiffness-adjustable flexible continuum robotic arm system according to claim 9, characterized in that, The driving device includes three driving mechanisms, each including a guide cylinder, a rotating shaft, a winding disc, a linear translation drive gear, a rotation drive gear, a first motor, and a second motor. The rear of the rotating shaft is located in the guide cylinder, allowing it to slide within the cylinder. The rotating shaft has several spur gear sections, each located radially on the rotating shaft, arranged side-by-side along its length. The winding disc is connected to the front end of the rotating shaft. The linear translation drive gear meshes with the spur gear section at the front of the rotating shaft, with its axis perpendicular to the axis of the rotating shaft. The rotation drive gear meshes with the spur gear section at the front of the rotating shaft, with its axis parallel to the axis of the rotating shaft. The first motor drives the linear translation drive gear to rotate, and the second motor drives the rotation drive gear to rotate. The rear ends of the first, second, and third drive rods are respectively connected to the winding discs in the three drive mechanisms.

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