Variable-rigidity exoskeleton joint mechanism for knee joint rehabilitation

Abstract

The invention discloses a variable-rigidity exoskeleton joint mechanism for knee joint rehabilitation, belongs to the field of rehabilitation medical instruments, and aims to solve the problems of fixed rigidity, heavy structure and non-flexibility of power of an existing mechanism. The actuator comprises an actuator bearing assembly, an input shaft unit, an output shaft unit and a spring transmission unit. The spring transmission unit is connected with the input shaft unit and the output shaft unit, the input shaft unit comprises a planetary gear set, the output shaft unit comprises a driven rod with a sliding groove and a T-shaped pivot unit, the T-shaped pivot unit can slide along the sliding groove to adjust the initial stretching amount of a spring so as to change the rigidity, and the planetary gear set is matched with the spring to achieve flexible power transmission. The mechanism can adapt to different rehabilitation stages and gait cycles, is compact in structure, low in cost and light in weight, can relieve the burden of thigh muscles, and provides safe and efficient assistance for knee joint rehabilitation.

Description

Technical Field

[0001] This invention relates to the field of rehabilitation medical device technology, and in particular to a variable stiffness exoskeleton joint mechanism for knee joint rehabilitation. Background Technology

[0002] In the field of knee joint rehabilitation, postoperative knee surgery patients commonly experience lower limb muscle weakness and gait abnormalities, severely impacting their daily living abilities and rehabilitation outcomes. Exoskeleton joint mechanisms, as key assistive devices, need to adapt to the dynamic needs of patients at different rehabilitation stages and gait cycles. However, existing knee joint rehabilitation exoskeleton joint mechanisms have many unresolved issues, making it difficult to meet the personalized and safety requirements of clinical rehabilitation.

[0003] Traditional exoskeleton joint mechanisms generally employ a fixed stiffness design. This not only fails to adjust stiffness according to the different stress requirements of the knee joint during the gait cycle (such as the stance and swing phases), but also makes it difficult to adapt to the patient's rehabilitation process from the acute phase (when the knee joint is fragile and requires low stiffness cushioning) to the recovery phase (when stiffness needs to be gradually increased to enhance muscle strength). This fixed stiffness design easily leads to a mismatch between the exoskeleton's movement pattern and the human body's natural gait, increasing the burden on the thigh muscles, limiting the effectiveness of rehabilitation training, and may even cause secondary damage to the knee joint after surgery.

[0004] While some adjustable stiffness mechanisms can improve the above problems, they often rely on complex hydraulic transmissions or high-cost smart materials (such as shape memory alloys). These mechanisms are not only bulky and energy-intensive, but also difficult to maintain and expensive to manufacture, failing to meet the demands of rehabilitation training for lightweight, low-cost, and portable equipment. Furthermore, the power transmission in existing mechanisms is mostly rigid, lacking flexible cushioning, which can easily generate transmission shocks during knee flexion and extension movements, further affecting patient comfort and rehabilitation safety.

[0005] Based on the problems of traditional mechanisms such as "inability to adapt to gait cycles and rehabilitation stages, bulky structure and high cost, and lack of flexibility in power transmission", this invention provides a variable stiffness exoskeleton joint mechanism. Through a simple mechanical structure, it achieves flexible stiffness adjustment and smooth power transmission, adapts to the natural gait of the human body, and provides safer and more efficient auxiliary support for knee joint rehabilitation training. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by providing a variable stiffness exoskeleton joint mechanism for knee joint rehabilitation. To achieve the above objectives, the technical solution adopted by the present invention is as follows: A variable stiffness exoskeleton joint mechanism for knee joint rehabilitation includes: an actuator bearing assembly, an input shaft unit, an output shaft unit, and a spring transmission unit; The spring transmission unit connects the input shaft unit and the output shaft unit, and is used to realize power transmission and stiffness adjustment. The input shaft unit includes: a planetary gear set, an input spindle, an input shaft planet carrier, and several upper protruding bolts; The planetary gear set includes: an input shaft main gear, several input shaft driven gears that mesh with the input shaft main gear, and an internal gear ring that meshes with the input shaft driven gears; The internal gear ring is embedded in the upper end of the actuator bearing assembly. The input spindle passes through the bottom axis of the actuator bearing assembly and is fixedly connected to the bottom end of the input shaft main gear. The input shaft planetary carrier is set at the upper end of the planetary gear set. The bottom end of each upper protruding bolt is fixedly mounted in an input shaft driven gear, and the top of the upper protruding bolt passes through the planetary carrier of the input shaft; The output shaft unit includes: an output main shaft, a plurality of driven rods arranged along the circumference of the output main shaft, and a T-shaped pivot unit slidably disposed in the driven rods; The top of the output spindle passes through the top center of the actuator bearing assembly. The driven rod has a sliding groove along its thickness direction for the T-shaped pivot unit to slide. The T-shaped pivot unit is linked to the upper protruding bolt through a spring transmission unit. The T-type pivot unit includes: a screw slidably disposed in a sliding groove, a first limiting nut threadedly connected to the side wall of the screw, and a second limiting nut threadedly connected to the side wall of the screw; The screw is confined in the sliding groove by the first limiting nut.

[0007] Furthermore, the actuator support assembly includes: an input shaft base, an input shaft support housing, and a planetary gear set elevation base; The input shaft support housing is fixedly mounted on the bottom of the input shaft base; the planetary gear set elevation base is coaxially and fixedly connected to the upper end of the input shaft base; The internal gear ring is fitted into the upper end of the planetary gear set raised base, and the input spindle passes through the bottom axis of the input shaft base and is fixedly connected to the bottom end of the input shaft main gear.

[0008] Furthermore, the actuator carrier assembly also includes: a first output shaft limiting housing and a second output shaft limiting housing; The first output shaft limiting housing is fixedly disposed on the upper end of the planetary gear set raised base, and the second output shaft limiting housing is coaxially stacked on the outside of the first output shaft limiting housing. A guide rail is formed between the upper inner side of the first output shaft limiting housing and the upper inner side of the second output shaft limiting housing, and the driven rod is slidably disposed in the guide rail on the side away from the output main shaft. A support structure is fixedly provided on the upper inner side of the second output shaft limiting housing, and the top of the output main shaft passes through the top middle of the support structure.

[0009] Furthermore, the spring transmission unit consists of several springs, each spring having a hook fixedly installed at both ends. The hook at one end of the spring is connected to the upper end of the upper protruding bolt, and the hook at the other end of the spring is connected to the side wall of the screw and located between the first limit nut and the second limit nut.

[0010] Furthermore, a planetary gear set limiting housing is fixedly provided on the upper part of the planetary gear set, and the bottom of the planetary gear set limiting housing is fixedly connected to the planetary gear set raised base.

[0011] Furthermore, the support structure includes: a support shaft, and a plurality of support rods fixedly arranged along the circumference of the support shaft; The support shaft has a through hole along its thickness direction for the output spindle to pass through, and the side of the support rod away from the support shaft is fixedly connected to the inner side of the upper end of the second output shaft limiting housing.

[0012] Furthermore, keyways are provided at both ends of the input spindle and the output spindle. The input spindle is connected to the output end of the external drive motor through a coupling, and the output spindle is connected to the transmission structure of the external knee joint auxiliary exoskeleton through a coupling.

[0013] The present invention adopts the above technical solution and has the following technical effects compared with the prior art: This invention, through the cooperation of a spring transmission unit and a T-shaped pivot unit, can flexibly adjust the stiffness of the joint mechanism to adapt to the needs of different rehabilitation stages; the planetary gear set design, combined with the smoothness of the spring transmission, achieves stable and shock-free power transmission, reducing the burden on the thigh muscles; the guide rail and support structure of the actuator bearing component effectively prevent the driven parts from shifting; the keyway and coupling design of the input and output spindles enables convenient adaptation to external equipment; the overall structure is simple and compact, low in cost, lightweight, and easy to carry, providing safe and efficient auxiliary support for knee joint rehabilitation training. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the upper axial three-dimensional structure of the present invention; Figure 2 This is a schematic diagram of the lower axial side three-dimensional structure of the present invention; Figure 3 This is a cross-sectional three-dimensional structural diagram of the present invention; Figure 4 This is a three-dimensional structural diagram of the planetary gear set in this invention; Figure 5 This is a front view of the structure of the present invention with the planetary gear set limiting housing, the first output shaft limiting housing, and the second output shaft limiting housing removed. Figure 6This is a three-dimensional structural diagram of the axial side of the present invention with the planetary gear set limiting housing, the first output shaft limiting housing, and the second output shaft limiting housing removed. Figure 7 This is a three-dimensional structural diagram of the output shaft unit in this invention; The reference numerals in the attached figures are: 11. Input shaft base; 12. Input shaft support housing; 13. Planetary gear set raised base; 14. First output shaft limiting housing; 141. Guide rail; 15. Second output shaft limiting housing; 151. Support structure; 1511. Support shaft; 1512. Support rod; 21. Planetary gear set; 211. Input shaft main gear; 212. Input shaft driven gear; 213. Internal gear ring; 214. Planetary gear set limiting housing; 22. Input main shaft; 23. Input shaft planetary carrier; 24. Upper protruding bolt; 31. Output main shaft; 32. Driven rod; 321. Sliding groove; 33. T-type pivot unit; 331. Screw; 332. First limit nut; 333. Second limit nut; 41. Spring; 42. Hook. Detailed Implementation

[0015] 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.

[0016] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0017] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the invention. Example

[0018] This embodiment provides a variable stiffness exoskeleton joint mechanism for knee joint rehabilitation, including: an actuator bearing assembly, an input shaft unit, an output shaft unit, and a spring transmission unit; Among them, the actuator bearing assembly serves as the basic support structure of the entire mechanism, undertaking the functions of installation positioning and motion limitation of each component. It includes an input shaft base 11, an input shaft support housing 12, a planetary gear set raised base 13, a first output shaft limiting housing 14, a second output shaft limiting housing 15, and a support structure 151. The input shaft support housing 12 is fixedly mounted on the bottom of the input shaft base 11. The input shaft support housing 12 is rotatably connected to the side wall of the input spindle 22, limiting the lower end of the input spindle 22 to prevent it from shifting during rotation. The planetary gear set elevation base 13 is coaxially fixedly connected to the upper end of the input shaft base 11 by bolts. The upper end of the planetary gear set elevation base 13 has an annular groove for embedding and fixing the internal gear ring 213, while also providing sufficient installation space for the planetary gear set 21. The first output shaft limiting housing 1... 4. The second output shaft limiting housing 15 is coaxially stacked on the outside of the first output shaft limiting housing 14 and fixed to the upper end of the planetary gear set raised base 13 by screws. The two are positioned by a stepped surface. The upper inner side of the first output shaft limiting housing 14 and the upper inner side of the second output shaft limiting housing 15 form an annular guide rail 141. The height of the guide rail 141 is adapted to the thickness of the driven rod 32, which can guide the movement direction of the driven rod 32, prevent the driven rod 32 from radially deviating during rotation, and improve the matching degree between the exoskeleton and the human gait. The support structure 151 includes a support shaft 1511 and three support rods 1512. The support shaft 1511 has a through hole along its thickness direction, the diameter of which is adapted to the diameter of the output main shaft 31. The support rods 1512 are evenly distributed along the circumference of the support shaft 1511. The end away from the support shaft 1511 is fixedly connected to the inner side of the upper end of the second output shaft limiting shell 15 (integrated molding). The top of the output main shaft 31 is limited by the through hole to ensure the coaxial rotation of the output main shaft 31, thereby ensuring the stable operation of the exoskeleton leg transmission structure. The input shaft unit is responsible for receiving power from the external drive motor and transmitting it to the spring transmission unit. It includes a planetary gear set 21, an input main shaft 22, an input shaft planetary carrier 23, and several upper protruding bolts 24. The planetary gear set 21 consists of an input shaft main gear 211, three input shaft driven gears 212, and an internal gear ring 213. The input shaft main gear 211 is fixedly connected to the upper end of the input main shaft 22. The input shaft driven gears 212 are evenly distributed around the circumference of the input shaft main gear 211 and mesh with it. At the same time, the input shaft driven gears 212 mesh with the inner teeth of the internal gear ring 213, forming a planetary transmission structure. This structure can convert the rotation of the input main shaft 22 into a composite motion of "revolution and rotation" of the input shaft driven gears 212, so that the upper bolt 24 can move synchronously along the circumference, evenly pulling the spring 41, avoiding uneven spring deformation caused by excessive force at a single transmission point, and thus ensuring the stability and smoothness of power transmission. The upper part of the planetary gear set 21 is covered with planetary gears. The gear set limiting housing 214 is fixedly connected to the planetary gear set elevation base 13 by screws at its bottom, which can axially limit the planetary gear set 21 and prevent the input shaft from coming off the gear 212 during movement. The input shaft planet carrier 23 is set at the upper end of the planetary gear set 21, with a through hole in the middle that matches the input shaft main gear 211 and a guide hole on the edge that matches the upper protruding bolt 24. This can assist in synchronizing the movement of the input shaft driven gear 212 and the upper protruding bolt 24, further improving the transmission accuracy. The bottom end of the upper protruding bolt 24 is fixedly connected to the upper end face of the input shaft driven gear 212 by threads. The top of the upper protruding bolt 24 passes through the guide hole of the input shaft planet carrier 23 and extends out. The side wall of the extended end of the upper protruding bolt 24 is hooked with the hook 42 of the spring 41. The output shaft unit includes an output main shaft 31, several driven rods 32, and several T-shaped pivot units 33; Both ends of the output spindle 31 are provided with keyways. The bottom of the output spindle 31 is fixedly connected to one end of the driven rod 32. The top of the output spindle 31 passes through the through hole of the support shaft 1511 and can be connected to the lower leg transmission structure of the external knee joint auxiliary exoskeleton through a coupling. The keyway design allows the output spindle 31 to be adapted to different models of exoskeleton couplings, making it convenient to replace exoskeleton components according to the patient's height and leg length. The driven rod 32 is evenly distributed along the circumference of the output spindle 31 and is slidably set in the guide rail 141 on the side away from the output spindle 31. The driven rod 32 has a strip-shaped sliding groove 321 along its thickness direction. The length of the sliding groove 321 is adapted to the adjustment stroke of the T-type pivot unit 33, providing sufficient space for the sliding of the T-type pivot unit 33. The T-type pivot unit 33 includes a screw 331, a first limiting nut 332, and a second limiting nut 333. The screw 331 passes through a sliding groove 321. The first limiting nut 332 and the second limiting nut 333 are threaded to both sides of the screw 331, respectively. By tightening or loosening the first limiting nut 332, the screw 331 can be switched between "fixed" and "sliding" in the sliding groove 321, thereby adjusting the distance between the screw 331 and the upper protruding bolt 24. When the screw 331 slides towards the output spindle 31, the spring 4... The initial tension of spring 41 increases, thus improving the stiffness of the mechanism. When the screw 331 slides away from the output main shaft 31, the initial tension of spring 41 decreases, thus reducing the stiffness of the mechanism. At the same time, this adjustment method can also adapt to different stages of the gait cycle: during the support phase, the knee joint needs higher stiffness to support the body weight, so the screw 331 can be adjusted to a position closer to the output main shaft 31; during the swing phase, the knee joint needs lower stiffness for flexible flexion and extension, so the screw 331 can be adjusted to a position away from the output main shaft 31, making the exoskeleton movement more in line with the natural gait of the human body. The spring transmission unit connects the input shaft unit and the output shaft unit to achieve power transmission and stiffness adjustment. It consists of three springs 41 (the number of springs can be increased or decreased according to stiffness requirements). Each spring 41 has a hook 42 fixedly installed (integrated molding) at both ends. One end of the hook 42 is hooked into the side wall of the upper bolt 24, and the other end of the hook 42 is hooked into the side wall of the screw 331, located between the first limit nut 332 and the second limit nut 333. The second limit nut 333 can prevent the hook 42 from falling off the screw 331 and also prevent the spring 41 from shifting laterally during movement. The springs 41 are made of stainless steel, and the stiffness coefficient can be selected according to rehabilitation needs. By replacing springs with different stiffness coefficients or increasing or decreasing the number of springs, the stiffness adjustment range of the mechanism can be further expanded to meet the personalized needs of patients with different weights and different rehabilitation stages. In a preferred embodiment, the side wall of the upper protruding bolt 24 is provided with an annular hanging groove, and the hook 42 at one end of the spring 41 is hooked in the annular hanging groove. The input spindle 22 also has keyways at both ends, which are connected to the output end of the external drive motor through a coupling. The keyway design allows the input spindle 22 to be adapted to drive motors of different power, making it convenient to adjust the driving power according to the patient's muscle strength. The working process of this embodiment is as follows, which is divided into two stages: "stiffness pre-adjustment" and "dynamic assisted movement" based on the actual scenario of knee joint rehabilitation training: Stiffness pre-adjustment stage: Determine the target stiffness based on the patient's rehabilitation stage and individual condition. When selecting a suitable low-stiffness coefficient spring, loosen the first limit nut 332, slide the screw 331 away from the output main shaft 31 to reduce the initial tension of the spring 41, and tighten the first limit nut 332 to fix the position. When selecting a suitable high-stiffness coefficient spring, slide the screw 331 closer to the output main shaft 31 to increase the initial tension of the spring 41, ensuring that the mechanism stiffness can support the knee joint force when the patient walks. If it is necessary to further increase the stiffness, the number of springs can be increased, and synchronous transmission through evenly distributed springs can avoid excessive local force. Dynamic Assisted Movement Phase: The mechanism is mounted on the exoskeleton's knee joint via a coupling. The input spindle 22 connects to the exoskeleton's drive motor, and the output spindle 31 connects to the exoskeleton's lower leg transmission structure. When the patient walks, the drive motor outputs torque based on gait cycle signals (such as knee joint angle detected by sensors). This torque is transmitted to the input spindle 22 via the coupling, which drives the input shaft main gear 211 to rotate. The input shaft main gear 211 drives the input shaft driven by the gear 212 to perform "revolution and rotation" motion within the internal gear ring 213, synchronously driving the upper protruding bolt 24 to move circumferentially. The upper protruding bolt 24 is connected to the hanging... Hook 42 pulls spring 41, and the compliant torque (without rigid impact) generated by spring 41 is transmitted to screw 331; under the action of tension, screw 331 drives driven rod 32 to rotate along guide rail 141, driven rod 32 to rotate synchronously with output spindle 31; output spindle 31 drives exoskeleton lower leg transmission structure through coupling, driving patient's lower leg to perform flexion and extension movements. Throughout the process, the elastic deformation of spring 41 can buffer the instantaneous torque fluctuation of drive motor, avoiding the impact of rigid transmission on the postoperative knee joint. At the same time, the uniform transmission of planetary gear set 21 makes the exoskeleton movement conform to the natural gait of the human body, reducing the load on thigh muscles. Gait adaptation adjustment: If the patient experiences gait incoordination during walking (such as the lower leg swinging too fast or too slow), the position of the T-shaped pivot unit 33 can be finely adjusted. If the swing is too fast, the screw 331 is finely adjusted towards the output main shaft 31 to increase the initial tension of the spring 41, improve the rigidity of the mechanism, and slow down the swing speed of the lower leg. If the swing is too slow, the opposite adjustment is made to ensure real-time adaptation between the exoskeleton and the human gait.

[0019] In summary, this invention achieves smooth power transmission and flexible stiffness adjustment through a combination of planetary gear sets and spring transmission. This not only adapts to the needs of patients at different rehabilitation stages and with varying weights but also conforms to the dynamic changes in the gait cycle, simulating the antagonistic effects of human muscles. The T-shaped pivot unit and replaceable spring design further expand the stiffness adjustment range and reduce the burden on patients. The overall structure is simple and compact, with low manufacturing costs and convenient installation and disassembly, providing safe, efficient, and personalized auxiliary support for the rehabilitation training of patients after knee surgery.

[0020] The above description of the present invention is merely a preferred embodiment of the present invention and does not limit the implementation and protection scope of the present invention. Those skilled in the art should realize that any equivalent substitutions and obvious changes made based on the description and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. A variable stiffness exoskeleton joint mechanism for knee joint rehabilitation, characterized in that, include: The actuator carrier assembly, input shaft unit, output shaft unit, and spring drive unit; The spring transmission unit connects the input shaft unit and the output shaft unit. The input shaft unit includes: a planetary gear set (21), an input spindle (22), an input shaft planet carrier (23), and several upper protruding bolts (24). The planetary gear set (21) includes: an input shaft main gear (211), a plurality of input shaft driven gears (212) meshing with the input shaft main gear (211), and an internal gear ring (213) meshing with the input shaft driven gears (212). The internal gear ring (213) is embedded in the upper end of the actuator bearing assembly; The input spindle (22) passes through the bottom axis of the actuator bearing assembly and is fixedly connected to the bottom end of the input shaft main gear (211); The input shaft planetary carrier (23) is located at the upper end of the planetary gear set (21); The bottom end of each of the upper protruding bolts (24) is fixedly disposed in one of the input shaft slave gears (212), and the top of the upper protruding bolts (24) penetrates the input shaft planetary carrier (23). The output shaft unit includes: an output main shaft (31), a plurality of driven rods (32) arranged around the circumference of the output main shaft (31), and a T-shaped pivot unit (33) slidably arranged in the driven rods (32). The top of the output spindle (31) passes through the top center of the actuator bearing assembly. The driven rod (32) has a sliding groove (321) along its thickness direction for sliding of the T-shaped pivot unit (33). The T-shaped pivot unit (33) is linked with the upper bolt (24) through the spring transmission unit. The T-shaped pivot unit (33) includes: a screw (331) slidably disposed in the sliding groove (321), a first limiting nut (332) threadedly connected to the side wall of the screw (331), and a second limiting nut (333) threadedly connected to the side wall of the screw (331). The screw (331) is confined in the sliding groove (321) by the first limiting nut (332).

2. The variable stiffness exoskeleton joint mechanism according to claim 1, characterized in that, The actuator support assembly includes: an input shaft base (11), an input shaft support housing (12), and a planetary gear set elevation base (13). The input shaft support housing (12) is fixedly disposed at the bottom of the input shaft base (11); the planetary gear set shim base (13) is coaxially and fixedly connected to the upper end of the input shaft base (11); The internal gear ring (213) is embedded in the upper end of the planetary gear set raised base (13), and the input spindle (22) passes through the bottom axis of the input shaft base (11) and is fixedly connected to the bottom end of the input shaft main gear (211).

3. The variable stiffness exoskeleton joint mechanism according to claim 2, characterized in that, The actuator carrier assembly further includes: a first output shaft limiting housing (14) and a second output shaft limiting housing (15). The first output shaft limiting housing (14) is fixedly disposed on the upper end of the planetary gear set shim base (13), and the second output shaft limiting housing (15) is coaxially stacked on the outside of the first output shaft limiting housing (14). A guide rail (141) is formed between the upper inner side of the first output shaft limiting housing (14) and the upper inner side of the second output shaft limiting housing (15). The driven rod (32) is slidably disposed in the guide rail (141) on the side away from the output main shaft (31). The upper inner side of the second output shaft limiting housing (15) is fixedly disposed on the support structure (151), and the top of the output main shaft (31) passes through the top middle of the support structure (151).

4. The variable stiffness exoskeleton joint mechanism according to claim 1, characterized in that, The spring transmission unit is composed of several springs (41), and each spring (41) has a hook (42) fixedly provided at both ends. The hook (42) at one end of the spring (41) is hooked to the upper end of the upper protruding bolt (24), and the hook (42) at the other end of the spring (41) is hooked to the side wall of the screw (331) and located between the first limiting nut (332) and the second limiting nut (333).

5. The variable stiffness exoskeleton joint mechanism according to claim 1, characterized in that, The upper part of the planetary gear set (21) is fixedly provided with a planetary gear set limiting shell (214), and the bottom of the planetary gear set limiting shell (214) is fixedly connected to the planetary gear set raising base (13).

6. The variable stiffness exoskeleton joint mechanism according to claim 3, characterized in that, The support structure (151) includes: a support shaft (1511) and a plurality of support rods (1512) fixedly arranged along the circumference of the support shaft (1511). The support shaft (1511) has a through hole along its thickness direction for the output spindle (31) to pass through, and the support rod (1512) is fixedly connected to the inner side of the upper end of the second output shaft limiting housing (15) on the side away from the support shaft (1511).

7. The variable stiffness exoskeleton joint mechanism according to claim 1, characterized in that, Both ends of the input spindle (22) and the output spindle (31) are provided with keyways. The input spindle (22) is connected to the output end of an external drive motor through a coupling, and the output spindle (31) is connected to the transmission structure of an external knee joint auxiliary exoskeleton through a coupling.

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