A rigid-flexible hybrid variable stiffness continuum manipulator

Abstract

The application discloses a rigid-flexible mixed variable-stiffness continuum robot arm, which comprises a plurality of continuum modules and two flexible joint modules, wherein each of the continuum modules comprises two driving mechanisms, a continuum, two groups of cable assemblies and a plurality of stiffness enhancement mechanisms; the two driving mechanisms are arranged on two outer end surfaces of the continuum in a 90-degree form, respectively; a connecting groove is formed on each of the two driving mechanisms, and a connecting part is arranged in the connecting groove and connected with a joint connector; one end of each of the two groups of cable assemblies is connected with a power end of each of the two driving mechanisms, and the other end of each of the two groups of cable assemblies is fixed on two inner end surfaces of the continuum; the plurality of stiffness enhancement mechanisms are arranged on the continuum at intervals; and the two groups of cable assemblies pass through the plurality of stiffness enhancement mechanisms which are located on the same line, respectively; and the stiffness enhancement mechanisms are used for compressing the cable assemblies to increase friction and improve the stiffness of the continuum.

Description

Technical Field

[0001] This invention relates to a rigid-flexible hybrid structure for a continuum robot, specifically a rigid-flexible hybrid variable stiffness continuum robot arm. It involves the variable stiffness design of arm segments of a continuum robot, where these segments form part or multiple segments of the full-length arm, enabling the fulfillment of inherently safe interaction and specific functional requirements for service robots. Background Technology

[0002] Continuum robots, also known as continuum robots, are robots that include flexible curved sections and whose shape is controlled by deforming these sections. Unlike traditional rigid-link robots, continuum robots offer several advantages: First, they can move along curves in narrow spaces or environments with debris where rigid-link robots would get stuck; second, they are inherently flexible and can operate even in situations involving pushing or collisions; and third, they offer good safety and high dexterity.

[0003] However, existing continuum robots suffer from low rigidity and insufficient load-bearing capacity. Furthermore, when operating in complex unstructured environments, task requirements generally necessitate adjustable stiffness within a certain range. Existing continuum robots either lack adjustable stiffness or exhibit poor adjustable stiffness. Moreover, current continuum robot drive disc motors are primarily designed separately from the continuum itself, leading to increasingly pronounced structural coupling effects as the number of segments increases. Additionally, many current continuum robots mount drive units such as actuators for driving wiring within the base, and the stiffness of the wiring used as the flexible section decreases as the diameter of the flexible section decreases. Therefore, if the central axis of the continuum robot twists, the correlation between the wiring's drive quantity and the continuum robot's (flexible section's) posture deviates from the design value due to the twist, potentially degrading the control performance accuracy of the continuum robot (flexible section). Therefore, it is necessary to provide a rigid-flexible hybrid variable stiffness continuum robot arm that, while meeting stiffness requirements, makes the robot safer, more flexible, and enhances its interaction capabilities and agility with humans and the environment. Summary of the Invention

[0004] The purpose of this invention is to provide a flexible-rigid hybrid variable stiffness continuous robotic arm that can meet certain requirements for rigidity and adjustable stiffness, while also having good safety performance and high flexibility. This solves the technical problems of existing continuous robotic arms having low rigidity, non-adjustable stiffness, and poor control performance precision.

[0005] To achieve the above-mentioned technical objectives, the present invention provides a variable stiffness continuous body robotic arm, comprising several continuous body modules and two flexible joint modules.

[0006] Each continuum module includes two drive mechanisms, a continuum, two sets of steel cable assemblies, and multiple stiffness lifting mechanisms. The two drive mechanisms are spatially mounted at 90° angles to the two outer end faces of the continuum, and each drive mechanism has a connecting part. One end of each set of steel cable assemblies is connected to the power end of the two drive mechanisms, and the other end is fixed to the two inner end faces of the continuum. Multiple stiffness lifting mechanisms are arranged at intervals on the continuum. Each set of steel cable assemblies passes through multiple stiffness lifting mechanisms located on the same straight line as itself. The stiffness lifting mechanisms press the steel cable assemblies to increase friction and thus improve the stiffness of the continuum.

[0007] The continuous modules are connected end to end in sequence through the connecting parts, and the continuous modules at both ends are respectively connected to the two flexible joint modules through the connecting parts.

[0008] In one embodiment, the flexible joint module includes two motors, two variable stiffness joints, a joint bracket, and a joint connector. The joint bracket has a first mounting surface and a second mounting surface that are perpendicular to each other. The first variable stiffness joint and the second motor are respectively fixedly mounted on the first mounting surface and the second mounting surface. The first motor is drivenly connected to the first variable stiffness joint, and the second motor is drivenly connected to the second variable stiffness joint. The second variable stiffness joint is connected to the joint connector, and the joint connector is connected to the connecting portion of the continuum module located at both ends.

[0009] In one embodiment, both the first and second variable stiffness joints are robot variable stiffness joints based on SMA spring-driven leaf springs.

[0010] In one embodiment, a harmonic reducer is provided between the first motor and the first variable stiffness joint, and between the second motor and the second variable stiffness joint.

[0011] In one embodiment, the continuum includes a plurality of support discs and a mandrel, the mandrel passing through the center of the plurality of support discs such that the plurality of support discs are connected to the mandrel at the same spacing, and four stiffness-enhancing mechanisms are uniformly arranged on one side of each support disc.

[0012] In one embodiment, the stiffness-enhancing mechanism includes a slide, a slider, and an SMA spring. The slide is fixed on the support plate, and a groove is formed along its length. The SMA spring is disposed in the groove, with one end fixed in the groove and the other end abutting against the slider. A through hole for a rope to pass through is formed at the end of the groove away from the SMA spring. The slider moves within the groove under the action of the SMA spring to gradually compress the rope and increase the stiffness of the continuous body.

[0013] In one embodiment, semiconductor silicon wafers are attached to the outer sides of the carriage.

[0014] In one embodiment, each of the drive mechanisms includes two motors, a third and a fourth motor, a drive mechanism bracket, and two cable winches. The drive mechanism bracket is fixed on the bracket plate. The third and fourth motors are arranged side by side or side by side inside the drive mechanism bracket. The two cable winches are respectively connected to the transmission ends of the third and fourth motors.

[0015] In one embodiment, each set of the cable assembly includes a plurality of fixed pulleys and a rope fixed to the support discs at both ends, one end of the rope being wound around the cable winch via the fixed pulleys, and the other end of the rope passing through a plurality of the stiffness adjustment mechanisms and fixed to the support disc at the far end.

[0016] In one embodiment, a reinforcing rib is provided between the first mounting surface and the second mounting surface of the joint bracket.

[0017] Compared with the prior art, the beneficial effects of the present invention mainly include:

[0018] This invention provides a rigid-flexible hybrid variable stiffness continuous robotic arm. First, by incorporating a stiffness-enhancing mechanism within the continuous module, the stiffness of the continuous robotic arm is increased by gradually compressing the cable assembly, thereby increasing friction. The stiffness reaches its maximum value when the stiffness-enhancing mechanism locks the cable assembly. Second, by arranging two drive mechanisms at 90-degree angles in space, each driving two horizontal or longitudinal ropes, the length of the ropes is changed, causing the continuous body to bend and deform, thus altering its stiffness. Third, a modular design is adopted, comprising multiple continuous module segments. Each segment of the continuous body module is an independent module. Therefore, the driving and stiffness adjustment between each module are relatively independent, avoiding the driving coupling problem caused by the separate setting of the drive disc motor and the continuous body in multi-segment continuous body robots. At the same time, the modular design makes the drive wiring as short as possible, and when the stiffness lifting mechanism locks the cable assembly, the length of the cable assembly in each continuous body module remains unchanged. This can effectively suppress the problem that the continuous body robot arm (flexible part) may twist around the central axis of the continuous body robot arm when it comes into contact with the inner wall of the body cavity, etc. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the variable stiffness continuum robotic arm described in this invention;

[0020] Figure 2 This is a schematic diagram of the structure of a variable stiffness continuum robotic arm according to one embodiment of the present invention;

[0021] Figure 3 This is a schematic diagram of the structure of the continuum module described in this invention;

[0022] Figure 4 yes Figure 3 A schematic diagram of the structure of the support plate described in the figure;

[0023] Figure 5 yes Figure 4 A magnified view of a portion of the image;

[0024] Figure 6 yes Figure 3 A schematic diagram of the stiffness enhancement mechanism described above;

[0025] Figure 7 This is a schematic diagram of the structure of the first flexible joint module of the present invention;

[0026] Figure 8 This is a schematic diagram of the structure of the second flexible joint module of the present invention;

[0027] Figure 9 This is a schematic diagram of the variable stiffness joint described in this invention.

[0028] As shown in the figure:

[0029] 100-First flexible joint module, 110-First motor, 120-Second motor, 130-First variable stiffness joint, 131-Main shaft, 132-Fixing block, 133-Sliding block, 1331-Inner groove, 134-Leaf spring, 135-Second SMA spring, 140-Second variable stiffness joint, 150-Joint bracket, 151-First mounting surface, 152-Second mounting surface, 160-Joint connector, 170-Flange, 180-Reinforcing rib;

[0030] 200 - Second flexible joint module; 210 - Harmonic reducer;

[0031] 300 - Continuous body module, 310 - Drive mechanism, 311 - Third motor, 312 - Fourth motor, 313 - Drive mechanism support, 314 - Cable winch, 320 - Continuous body, 321 - Support plate, 322 - Mandrel, 330 - Cable assembly, 331 - Fixed pulley, 332 - Rope, 340 - Stiffness lifting mechanism, 341 - Carriage, 342 - Slider, 343 - SMA spring, 344 - Through hole. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0033] This embodiment uses a continuous robotic arm composed of two continuous modules as an example to describe in detail a variable stiffness continuous robotic arm with a rigid-flexible hybrid design proposed in this invention.

[0034] like Figures 1-2 As shown, this embodiment provides a rigid-flexible hybrid variable stiffness continuous body robotic arm, including two continuous body modules and two flexible joint modules. The two flexible joint modules are a first flexible joint module 100 and a second flexible joint module 200, respectively. The two continuous body modules are connected together by the continuous body module 300 to form a continuous body body. The first flexible joint module 100 and the second flexible joint module 200 are respectively connected to the two ends of the continuous body body. The first flexible joint module 100 is fixed to the base end of the robotic arm, and the second flexible joint module 200 is connected to the execution end of the robotic arm for subsequent actions.

[0035] The variable stiffness continuous robotic arm provided in this embodiment adopts a modular design, specifically including two continuous modules 300. Each continuous module 300 contains its own drive mechanism. The drive mechanisms of each module independently adjust their stiffness, avoiding the technical problem of drive coupling caused by the separate setting of the drive disc motor and the continuous body in multi-segment continuous robots. At the same time, each continuous module 300 is also provided with a stiffness lifting mechanism, which can gradually compress the rope, increase the friction between the rope and the continuous body, and thus improve the stiffness of the continuous robotic arm. Of course, in other embodiments besides this one, the number of continuous modules 300 is not limited, and there can be multiple segments. Multiple continuous modules 300 are connected together by opening male and female slots.

[0036] Among them, such as Figures 3-5 As shown, in this embodiment, the continuum module 300 includes two drive mechanisms 310, a continuum 320, two sets of steel cable assemblies 330, and multiple stiffness-enhancing mechanisms 340. The two drive mechanisms 310 are spatially mounted at 90° angles to the two outer end faces of the continuum 320, and each drive mechanism 310 has a connecting portion. The two sections of the continuum module 300 are connected through the connecting portion. Simultaneously, both ends of the continuum module 300 are also connected to the first flexible joint module 100 and the second flexible joint module 100 through the connecting portion, respectively. Block 200 is connected; one end of each of the two sets of steel cable assemblies 330 is connected to the power end of each of the two drive mechanisms 310, and the other end is fixed to the two inner end faces of the continuous body 320. Multiple stiffness lifting mechanisms 340 are arranged at intervals on the continuous body 320. The four ropes 331 of the two sets of steel cable assemblies 330 pass through multiple stiffness lifting mechanisms 340 located on the same straight line. The stiffness lifting mechanisms 340 press the ropes 332 to increase friction, thereby improving the stiffness of the continuous body 320.

[0037] Preferably, the continuum 320 is composed of a plurality of support discs 321 and a core rod 322, wherein the core rod 322 passes through the center of the plurality of support discs 321 such that the plurality of support discs 321 are connected to the core rod 322 at the same spacing, and four stiffness lifting mechanisms 340 are uniformly arranged on one side of each support disc 321.

[0038] Preferably, the mandrel 322 is made of polypropylene material, and a rubber support is wrapped around the outside of the mandrel 322.

[0039] Preferably, each drive mechanism 310 includes a third motor 311, a fourth motor 312, a drive mechanism bracket 313, and two cable winches 314. The drive mechanism bracket 313 is made of multiple metal plates fixed together by countersunk screws and fixed to the bracket plate 321 by countersunk screws. The third motor 311 and the fourth motor 312 are arranged side by side or side by side in the drive mechanism bracket 313. That is, if the third motor 311 and the fourth motor 312 of one end of the drive mechanism 310 are arranged side by side, then the third motor 311 and the fourth motor 312 of the other end of the drive mechanism 310 are arranged side by side. This satisfies the requirement that the two drive mechanisms 310 are arranged in a 90° spatial configuration. Furthermore, this arrangement of the third motor 311 and the fourth motor 312 is based on the requirement that two of the ropes 332 be arranged in parallel side by side or two in parallel side by side. The cable winch 314 is connected to the transmission ends of the third motor 311 and the fourth motor 312, respectively. The cable assembly 330 includes multiple fixed pulleys 331 and ropes 332 fixed on the support discs 321 at both ends. One end of the rope 332 is wound around the cable winch 314 through the fixed pulleys 331, and the other end of the rope 332 passes through multiple stiffness lifting mechanisms 340 and is fixed to the support disc 321 at the far end. Thus, the drive mechanisms 310 on both sides of the continuum 320 each control a set of horizontal or longitudinal ropes 332. When the third motor 311 and the fourth motor 312 are working, they drive their respective cable winches 314 to rotate, thereby changing the length of the ropes 332. This causes the polypropylene mandrel 322 and the external rubber support to bend and deform, thereby changing the stiffness of the continuum 320.

[0040] Preferred, such as Figure 6As shown, the stiffness lifting mechanism 340 includes a slide 341, a slider 342, and an SMA spring 343. The slide 341 is fixed to the support plate 321 by countersunk screws. The slide 341 has a groove along its length. The SMA spring 343 is disposed in the groove, with one end fixed in the groove by a pin. The other end of the SMA spring 343 abuts against the slider 342. The end of the groove away from the SMA spring 343 has a through hole 344 for a rope to pass through. 3. Made of SMA metal wire, its outer diameter is larger than the width of the groove opening to ensure that the SMA spring 343 will not fall out in a certain direction. In addition, semiconductor silicon wafers are attached to both sides of the outer side of the slide 341. By heating, the stiffness of the SMA spring 343 is changed, causing it to push the slider 342 to compress the rope 332 in the through hole 344, gradually tightening the rope 332. This increases the friction between the rope 332 and the support plate 321, thereby increasing the bending and torsional stiffness of the continuous body 320 and improving the stiffness of the continuous body 320. In addition, when the slider 342 tightens and locks the rope 332, the stiffness lifting mechanism 340 also acts as a locking mechanism, preventing the rope 332 from slipping.

[0041] Preferred, such as Figure 7 As shown, the first flexible joint module 100 includes a first motor 110, a second motor 120, a first variable stiffness joint 130, a second variable stiffness joint 140, a joint support 150, and a joint connector 160. The joint support 150 has a first mounting surface 151 and a second mounting surface 152 that are perpendicular to each other. The first variable stiffness joint 130 and the second motor 120 are respectively fixedly mounted on the first mounting surface 151 and the second mounting surface 152. One end of the first motor 110 is drivenly connected to the first variable stiffness joint 130, and the other end is fixed to the base end of the robot arm. One end of the second variable stiffness joint 140 is drivenly connected to the second motor 120, and the other end is connected to the joint connector 160 to connect to the continuum module 300.

[0042] In a further preferred embodiment, the other end of the first motor 110 is fixed to the base end via a flange 170.

[0043] More preferably, a reinforcing rib 180 is provided between the first mounting surface 151 and the second mounting surface 152 of the joint bracket 150 to increase the strength and stability of the joint bracket 150.

[0044] Preferred, such as Figure 8As shown, the structure of the second flexible joint module 200 is basically the same as that of the first flexible joint module 100. The difference is that harmonic reducers 210 are provided between the first motor 110 and the first variable stiffness joint 130, and between the second motor 120 and the second variable stiffness joint 140 in the second flexible joint module 200. Since the second flexible joint module 200 is connected to the execution end of the robot arm, the addition of the harmonic reducer 210 facilitates obtaining a larger torque at the execution end of the robot arm. In addition, the other end of the first motor 110 of the second flexible joint module 200 is connected to the execution end of the robot arm through a flange 170 to perform corresponding actions.

[0045] It should be noted that the first variable stiffness joint 130 and the second variable stiffness joint 140 used in the first flexible joint module 100 and the second flexible joint module 200 have the same structure. They are both robot variable stiffness joints based on SMA springs driving leaf springs. This technology is based on the invention patent application filed by the applicant on July 29, 2022, entitled "Robot Variable Stiffness Joint Based on SMA Spring Driving Leaf Spring", with application number 202210905781.3. By heating the heating element to control the temperature of the SMA spring, the change in the length of the SMA spring is controlled, thereby causing the leaf spring to bend at different positions to achieve the purpose of variable stiffness, thereby improving the smoothness and flexibility of robot movement.

[0046] Specifically, since the first variable stiffness joint 130 and the second variable stiffness joint 140 have the same structure, the structure and working principle of the variable stiffness joint will be explained in detail below using the first variable stiffness joint 130 as an example.

[0047] like Figure 9As shown, the first variable stiffness joint 130 includes a main shaft 131 for connecting the driving wheel and the driven wheel, a fixed block 132 and a sliding block 133 disposed on the driving wheel, a leaf spring 134 connected to the sliding block 133, and a second SMA spring 135 whose two ends are respectively connected to the fixed block 132 and the sliding block 133. The fixed block 132 is fixedly disposed on the side of the driving wheel near the driven wheel, and the sliding block 133 is disposed in a groove of the driving wheel. The fixed block 132 and the sliding block 133 are evenly disposed at a 120° interval. One end of the second SMA spring 135 is fixed to the driving wheel. One end of the fixed block 132 is connected to the sliding block 133. One end of the leaf spring 134 is set on the inner groove 1331 of the sliding block 133, and the other end is fixed on the inner side wall of the driven wheel. When the second SMA spring 135 is heated by the heating element, the length of the second SMA spring 135 changes, thereby driving the sliding block 133 to slide in the groove of its driving wheel, so that the position of the leaf spring 134 in the inner groove 1331 changes, and thus the leaf spring 134 bends at different positions in the inner groove 1331 to achieve the purpose of variable stiffness. When the second SMA spring 135 is not heated, the temperature of the SMA spring remains constant and it does not deform. At this time, the sliding block 133 is located at the very end of the leaf spring 134, and the stiffness of the entire robot joint is at its minimum. When the second SMA spring 135 is heated to its maximum temperature, the second SMA spring 135 elongates, causing the sliding block 133 to move to the root of the leaf spring 134. At this time, the entire robot joint is approximately rigid. By adjusting the temperature, the degree of heating of the second SMA spring 135 can be controlled, thereby affecting the change in the length of the second SMA spring 135. This allows the stiffness of the leaf spring 134 to be arbitrarily adjusted between minimum and approximately rigid, achieving the purpose of variable stiffness. It should be noted that the above only describes the differences between this invention and the aforementioned patent application with application number 202210905781.3. Other structures and principles are the same, so they will not be repeated here.

[0048] In addition, in this embodiment, the joint connector 160 of the first flexible joint module 100 and the joint connector 160 of the second flexible joint module 200 are respectively provided with female grooves and male grooves for connecting with the drive mechanisms 310 at both ends of the continuum module 300. Correspondingly, the drive mechanism bracket 313 is also provided with male grooves and female grooves for connecting with the first flexible joint module 100 and the second flexible joint module 200 at both ends or for connecting with multiple continuum modules 300.

[0049] In this embodiment, the first motor 110, the second motor 120, the third motor 311 and the fourth motor 312 are all disc motors, wherein the first motor 110 and the second motor 120 are disc motors of the same model, and the third motor 311 and the fourth motor 312 are disc motors of the same model.

[0050] In summary, the rigid-flexible hybrid variable stiffness continuous robotic arm provided by this invention has the following advantages:

[0051] Beneficial effects:

[0052] 1. The variable stiffness continuous robotic arm designed in this invention utilizes the characteristic that the length of a spring made of SMA material changes after heating to improve the stiffness and stiffness adjustment capability of the continuous robotic arm. Specifically, an SMA spring 343 is set in the stiffness lifting mechanism 340. The change in the length of the SMA spring 343 drives the slider 342 to gradually press the rope 332, increasing the friction between the rope 332 and the support plate 321, thereby increasing the bending and torsional stiffness of the continuous body 320. By setting variable stiffness joints in the first flexible joint module 100 and the second flexible joint module 200, the variable stiffness joints are robot variable stiffness joints based on SMA springs driving leaf springs. By adjusting the temperature, the degree of heating of the second SMA spring 135 can be controlled, thereby affecting the change in the length of the second SMA spring 135, so that the stiffness of the leaf spring 134 can be arbitrarily adjusted between minimum and near-rigid, achieving the purpose of variable stiffness.

[0053] 2. The variable stiffness continuous robotic arm designed in this invention adopts a modular design, including multiple continuous modules 300, each of which is an independent module. Therefore, the driving and stiffness adjustment between each module are relatively independent, avoiding the driving coupling problem caused by the separate setting of the drive disc motor and the continuous body in multi-segment continuous robots. At the same time, the modular design makes the drive wiring as short as possible. The core rod 322 is made of polypropylene material, and a rubber support is wrapped around the outside of the core rod 322. The use of this composite material structure can ensure that the axial incompressibility is guaranteed, thereby increasing the friction between the drive wiring and the support disc 321 (until it is close to locking). When locked, when the flexible part of the continuous robotic arm bends, the length of the rope 332 in each segment remains unchanged, thereby effectively suppressing the problem that the continuous robot (flexible part) may twist around the central axis of the continuous robot when the flexible part of the continuous robot contacts the inner wall of the body cavity, etc.

[0054] 3. The variable stiffness continuous robotic arm designed in this invention has a second flexible joint module 200 connected to the robotic arm's execution end, which is similar in configuration to a traditional collaborative robotic arm (a series connection of a harmonic reducer and a force sensor). However, each joint is composed of VSA (variable stiffness series elastic drive unit), which has independent stiffness adjustment capability. While implementing the inherently safe technical route, it also takes into account the practicality issues of rigidity and rhythm during robot movement. This allows the variable stiffness continuous robotic arm of this invention to meet certain stiffness and accuracy requirements, while also having good safety performance and high flexibility, and to meet the inherently safe interaction and specific functional requirements of service robots.

[0055] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A flexible-rigid hybrid variable stiffness continuous robotic arm, characterized in that, It includes several continuum modules and two flexible joint modules; Each continuum module includes two drive mechanisms, a continuum, two sets of steel cable assemblies, and multiple stiffness lifting mechanisms. The two drive mechanisms are spatially mounted at 90° angles to the two outer end faces of the continuum, and each drive mechanism has a connecting part. One end of each set of steel cable assemblies is connected to the power end of the two drive mechanisms, and the other end is fixed to the two inner end faces of the continuum. Multiple stiffness lifting mechanisms are arranged at intervals on the continuum. Each set of steel cable assemblies passes through multiple stiffness lifting mechanisms located on the same straight line as itself. The stiffness lifting mechanisms press the steel cable assemblies to increase friction and thus improve the stiffness of the continuum. The continuous body modules are connected end to end in sequence through the connecting part, and the continuous body modules at both ends are respectively connected to the two flexible joint modules through the connecting part; The continuum includes multiple support discs and a core rod, the core rod passing through the center of the multiple support discs such that the multiple support discs are connected to the core rod at the same spacing, and four stiffness lifting mechanisms are evenly arranged on one side of each support disc; The stiffness-enhancing mechanism includes a slide, a slider, and an SMA spring. The slide is fixed on the support plate and has a groove along its length. The SMA spring is disposed in the groove, with one end fixed in the groove and the other end abutting against the slider. The end of the groove away from the SMA spring has a through hole for a rope to pass through. The slider moves in the groove under the action of the SMA spring to gradually compress the rope and increase the stiffness of the continuous body.

2. The rigid-flexible hybrid variable stiffness continuous robotic arm according to claim 1, characterized in that, The flexible joint module includes two motors, two variable stiffness joints, a joint bracket, and a joint connector. The joint bracket has a first mounting surface and a second mounting surface that are perpendicular to each other. The first variable stiffness joint and the second motor are respectively fixedly mounted on the first mounting surface and the second mounting surface. The first motor is drivenly connected to the first variable stiffness joint, and the second motor is drivenly connected to the second variable stiffness joint. The second variable stiffness joint is connected to the joint connector, and the joint connector is connected to the connecting part of the continuum module located at both ends.

3. A rigid-flexible hybrid variable stiffness continuous robotic arm according to claim 2, characterized in that, Both the first and second variable stiffness joints are robot variable stiffness joints based on SMA spring-driven leaf springs.

4. A rigid-flexible hybrid variable stiffness continuous robotic arm according to claim 3, characterized in that, Harmonic reducers are provided between the first motor and the first variable stiffness joint, and between the second motor and the second variable stiffness joint.

5. A rigid-flexible hybrid variable stiffness continuous robotic arm according to claim 1, characterized in that, Semiconductor silicon wafers are attached to both outer sides of the carriage.

6. A rigid-flexible hybrid variable stiffness continuous robotic arm according to claim 1, characterized in that, Each of the drive mechanisms includes two motors, a third and a fourth motor, a drive mechanism bracket, and two cable winches. The drive mechanism bracket is fixed on the bracket plate. The third and fourth motors are arranged side by side or side by side inside the drive mechanism bracket. The two cable winches are respectively connected to the transmission ends of the third and fourth motors.

7. A rigid-flexible hybrid variable stiffness continuous robotic arm according to claim 6, characterized in that, Each of the steel cable assemblies includes multiple fixed pulleys and a rope fixed to the support discs at both ends. One end of the rope is wound around the steel cable winch through the fixed pulleys, and the other end of the rope passes through multiple stiffness lifting mechanisms and is fixed to the support disc at the far end.

8. A rigid-flexible hybrid variable stiffness continuous robotic arm according to claim 2, characterized in that, A reinforcing rib is provided between the first mounting surface and the second mounting surface of the joint bracket.

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