A robotic bionic knee joint mechanism

Abstract

The application relates to a robot bionic knee joint mechanism and belongs to the field of robot multi-freedom bionic mechanisms; a thigh structure component is vertically placed; a gear connecting rod component is installed at the bottom end of the thigh structure component; a driving gear component and a transmission gear connecting rod component are both arranged around the gear connecting rod component; the transmission gear connecting rod component and the driving gear component are both in meshing cooperation with the thigh structure component; the top of a shank structure component is in butt joint with the transmission gear connecting rod component; the transmission gear connecting rod component is in meshing rotation with the thigh structure component, thereby driving the shank structure component to move in translation relative to the thigh structure component; the two ends of a rotary connecting rod component are respectively in butt joint with the driving gear component and the middle part of the shank structure component; the driving gear component is in meshing rotation with the thigh structure component, thereby driving the shank structure component to rotate relative to the thigh structure component through the rotary connecting rod component; the application overcomes the problems of poor motion matching, complex composition, large volume and complex control of the knee joint bionic mechanism.

Description

Technical Field

[0001] This invention belongs to the field of multi-degree-of-freedom bionic mechanisms for robots, and relates to a bionic knee joint mechanism for robots. Background Technology

[0002] The multi-DOF biomimetic mechanism of the lower limb robot is inspired by the physiological structure and movement mechanism of human joints. It mimics the multi-DOF coupled motion of human joints, giving the robot joints biomimetic characteristics and achieving greater mobility and terrain adaptability. The human knee joint, composed of bones, soft tissues, ligaments, and muscles, is the most complex joint in the human body. Anatomical imaging analysis shows that knee flexion and extension movements are achieved through a complex motion of rolling and sliding between the tibia and femur, with temporal changes in the contact point and an instantaneous trajectory resembling a J-shaped curve. As the joint with the highest power output in human lower limb climbing movements, the knee joint mechanism needs to also possess load-bearing capacity. Currently, most knee joint mechanisms use single-pin, four-bar, parallel, or multi-hinge series mechanisms, which still suffer from poor motion matching, large size, heavy weight, and complex control.

[0003] Chinese patent CN112245081A describes a knee joint fixation brace. The knee joint mechanism uses a single-degree-of-freedom rotary joint. In this type of mechanism, the instantaneous center of rotation of the joint is fixed at a fixed point, which deviates from the movement of the human body. This leads to a mismatch between human and machine coordination. The additional internal interaction force generated during wear and exercise will put extra pressure on the human joint, increase the degree of joint wear, and pose a risk of joint damage.

[0004] Chinese patent CN112060057A describes a bionic knee joint mechanism based on a tensioned integral structure. This mechanism combines a tensioned integral structure with a four-bar linkage to achieve bionic joint movement and self-locking function. However, this joint mechanism is large in size and complex in composition. In addition, the structure requires the addition of multiple sets of springs, resulting in insufficient reliability during long-term operation.

[0005] Chinese patent CN115026795A describes an adaptive variable-instantaneous exoskeleton robot knee joint that uses a biomimetic curved surface design and rope-constrained contact motion between two curved surfaces to achieve rolling and sliding motion of the human knee joint. However, this method requires an additional mechanism for rope storage, and the low stiffness of the rope is not conducive to load transmission. Long-term operation also presents reliability and consistency issues. Summary of the Invention

[0006] The technical problem solved by this invention is to overcome the shortcomings of the prior art and propose a bionic knee joint mechanism for robots, which overcomes the problems of poor motion matching, complex composition, large size and complex control of bionic knee joint mechanisms.

[0007] The solution of the present invention is:

[0008] A bionic knee joint mechanism for robots includes a thigh structure component, a gear and linkage component, a drive gear component, a transmission gear and linkage component, a rotating linkage component, and a lower leg structure component;

[0009] The thigh structure component is placed vertically; the gear connecting rod component is installed at the bottom of the thigh structure component; both the drive gear component and the transmission gear connecting rod component are based on the gear connecting rod component as their axis; the transmission gear connecting rod component meshes with the thigh structure component; the drive gear component meshes with the thigh structure component; the top of the lower leg structure component is connected to the transmission gear connecting rod component; the lower leg structure component is driven to translate relative to the thigh structure component through the meshing and rotation of the transmission gear connecting rod component and the thigh structure component; one end of the rotating connecting rod component is connected to the drive gear component, and the other end of the rotating connecting rod component is connected to the middle of the lower leg structure component; the drive gear component meshes and rotates with the thigh structure component, driving the lower leg structure component to rotate relative to the thigh structure component through the rotating connecting rod component.

[0010] In the aforementioned bionic knee joint mechanism for robots, the thigh structural component includes an inner main structure, an outer gear structure, and a connecting structure.

[0011] The inner main structure is a vertically arranged plate-like structure; a first stationary gear is provided at the bottom of the inner main structure; the top of the connecting structure is installed in the middle of the inner main structure; a second stationary gear is provided at the bottom of the connecting structure; the first stationary gear and the second stationary gear are coaxial.

[0012] In the aforementioned bionic knee joint mechanism for robots, the gear linkage component includes an outer link, an inner link, and a fixed shaft;

[0013] The outer connecting rod and the inner connecting rod are arranged in parallel; the fixed shaft is installed vertically between the outer connecting rod and the inner connecting rod, and is located at the outer end of the outer connecting rod and the inner connecting rod, forming a U-shaped structure.

[0014] In the aforementioned bionic knee joint mechanism for robots, the thigh structure extends into the opening of the U-shaped structure; the inner ends of the outer and inner connecting rods are coaxially connected to the first and second stationary gears; thus enabling the gear and connecting rod assembly to rotate relative to the thigh structure with the axis of the first stationary gear as the axis.

[0015] In the aforementioned bionic knee joint mechanism for robots, the drive gear component includes a drive gear component gear and a drive gear component wheel;

[0016] The drive gear component disc is a vertically arranged disc structure; the drive gear component gear passes coaxially through the drive gear component disc; the part of the drive gear component gear located on the outside of the drive gear component disc is a gear structure; the part of the drive gear component gear located on the inside of the drive gear component disc is a rocker arm structure; the gear structure and the rocker arm structure are fixedly connected.

[0017] In the aforementioned bionic knee joint mechanism for robots, the drive gear component meshes with a first stationary gear through the gear structure of the drive gear component; the gear structure drives the rocker arm structure to rotate synchronously.

[0018] In the aforementioned bionic knee joint mechanism for robots, the transmission gear and linkage component includes a transmission gear and a transmission gear linkage;

[0019] One end of the transmission gear connecting rod is mounted on a fixed shaft; the gear of the transmission gear connecting rod component is fixedly installed on the side wall of the transmission gear connecting rod; the gear of the transmission gear connecting rod component meshes with the second stationary gear; the transmission gear connecting rod component rotates through meshing with the gear, thereby driving the transmission gear connecting rod to rotate; the other end of the transmission gear connecting rod is rotatably connected to the lower leg structure component.

[0020] In the aforementioned bionic knee joint mechanism for robots, the rotating link component includes a rotating link; two docking holes are provided at both ends of the rotating link; one docking hole is docked with the rocker arm structure of the drive gear component; the other docking hole is docked with the lower leg structure component.

[0021] In the aforementioned bionic knee joint mechanism for robots, the lower leg structure component includes a lower leg structure; the lower leg structure is designed with a swing connecting shaft and a rotary connecting shaft; the swing connecting shaft is located above the rotary connecting shaft; the swing connecting shaft is connected to the other end of the transmission gear connecting rod; the rotary connecting shaft is connected to another docking hole of the rotary connecting rod component.

[0022] In the aforementioned bionic knee joint mechanism for robots, the motion process of the knee joint mechanism is as follows:

[0023] The first stationary gear at the bottom of the inner main structure meshes with the gear on the drive gear component, forming a gear transmission pair through the gear connecting rod component; when the drive gear component wheel is driven to rotate externally, the gear connecting rod component rotates around the gear axis at the joint of the inner main structure and the outer gear structure, the drive gear component gear rotates around the fixed axis, and the drive gear component gear protruding from the rocker arm structure rotates around the fixed axis.

[0024] When the gear connecting rod assembly rotates around the gear shaft at the joint between the inner main structure and the outer gear structure, the shaft at the other end of the transmission gear connecting rod rotates around the fixed shaft.

[0025] The other end of the transmission gear connecting rod is connected to the swing connecting shaft of the lower leg structure via a rotary joint, so that when the other end of the transmission gear connecting rod rotates around the fixed axis, the swing connecting shaft of the lower leg structure moves in the plane, thereby realizing the translation of the lower leg structure relative to the thigh structure.

[0026] One end of the rotating link is connected to the rotating shaft of the gear protruding rocker arm structure of the drive gear component; the other end of the rotating link is connected to the rotating connecting shaft of the lower leg structure, so that when the rotating shaft of the gear protruding rocker arm structure of the drive gear component rotates around the fixed axis, the rotating connecting shaft of the lower leg structure component rotates around the swing connecting shaft of the lower leg structure component, thereby realizing the rotation of the lower leg structure component.

[0027] The advantages of this invention compared to the prior art are:

[0028] (1) This invention proposes a multi-link double-tooth meshing mechanism configuration. Through multi-parameter optimization of link dimensions and gear ratio, the rolling and sliding motion of the knee joint is decoupled, thereby achieving the purpose of biomimetic motion.

[0029] (2) The present invention designs two sets of parallel gears to jointly bear torque and pressure loads, achieving high reliability and large load capacity in a compact space based on motion matching.

[0030] (3) The present invention integrates a joint drive connection component, which can be adapted to components with various drive methods in a limited space and is simple to control;

[0031] (4) The multi-link double-tooth meshing mechanism proposed in this invention can achieve high-precision matching between the mechanism and the instantaneous center of motion of the human knee joint by designing gear and link parameters, with a maximum error of less than 0.7mm.

[0032] (5) This invention adopts a gear and linkage transmission combination, with a mechanism having 1 degree of freedom, ensuring stable motion when driven by external power. The transmission link has no springs, ropes, or other components, resulting in high transmission stiffness. It provides a wide range of motion for the calf and thigh, covering the entire range of human movement.

[0033] (6) The present invention uses two sets of gears, one inside and one outside, in parallel to jointly bear the joint load, which helps to reduce the gear module, achieve a compact mechanism, and is applicable to a variety of application scenarios.

[0034] (7) The present invention integrates the external drive interface structure into the two sets of parallel gears, which can be adapted to various drive methods such as direct drive and remote drive. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the extended position of the bionic knee joint mechanism of the present invention;

[0036] Figure 2This is a schematic diagram of the flexion position of the bionic knee joint mechanism of the present invention;

[0037] Figure 3 This is an exploded schematic diagram of the bionic knee joint mechanism of the present invention. Detailed Implementation

[0038] The present invention will be further described below with reference to the embodiments.

[0039] This invention provides a bionic knee joint mechanism for robots, which overcomes the problems of poor motion matching, complex composition, large size, and complex control of bionic knee joint mechanisms.

[0040] Robotic bionic knee joint mechanism, such as Figures 1 to 3 As shown, the structure specifically includes a thigh structural component 1, a gear and connecting rod component 2, a drive gear component 3, a transmission gear and connecting rod component 4, a rotating connecting rod component 5, and a lower leg structural component 6. The thigh structural component 1 is placed vertically; the gear and connecting rod component 2 is installed at the bottom end of the thigh structural component 1; both the drive gear component 3 and the transmission gear and connecting rod component 4 are axially aligned with the gear and connecting rod component 2; the transmission gear and connecting rod component 4 meshes with the thigh structural component 1; the drive gear component 3 meshes with the thigh structural component 1; the top of the lower leg structural component 6 is connected to the transmission gear and connecting rod component 4; the meshing and rotation of the transmission gear and connecting rod component 4 with the thigh structural component 1 drives the translational movement of the lower leg structural component 6 relative to the thigh structural component 1; one end of the rotating connecting rod component 5 is connected to the drive gear component 3, and the other end of the rotating connecting rod component 5 is connected to the middle of the lower leg structural component 6; the drive gear component 3 meshes and rotates with the thigh structural component 1, driving the rotation of the lower leg structural component 6 relative to the thigh structural component 1 through the rotating connecting rod component 5.

[0041] The thigh structure component 1 includes an inner main structure 11, an outer gear structure 12, and a connecting structure 13. The inner main structure 11 is a vertically arranged plate-like structure; a first stationary gear is provided at the bottom of the inner main structure 11; the top of the connecting structure 13 is installed in the middle of the inner main structure 11; a second stationary gear is provided at the bottom of the connecting structure 13; the first stationary gear and the second stationary gear are coaxial.

[0042] The thigh structural component 1 mainly includes an inner main body structure 11, an outer gear structure 12, and a connecting structure 13. The inner main body structure 11 and the outer gear structure 12 are designed with gears with a certain number of teeth at the joint. The axes of the two gears are coaxial, and the inner main body structure 11 and the outer gear structure 12 are fixedly connected by the connecting structure 13.

[0043] The gear connecting rod assembly 2 includes an outer connecting rod 21, an inner connecting rod 22, and a fixed shaft 23. The outer connecting rod 21 and the inner connecting rod 22 are arranged in parallel; the fixed shaft 23 is vertically installed between the outer connecting rod 21 and the inner connecting rod 22, and is located at the outer ends of the outer connecting rod 21 and the inner connecting rod 22, forming a U-shaped structure.

[0044] The thigh structure component 1 extends into the opening end of the U-shaped structure; the inner ends of the outer connecting rod 21 and the inner connecting rod 22 are coaxially connected to the first stationary gear and the second stationary gear; thus realizing that the gear connecting rod component 2 rotates relative to the thigh structure component 1 with the axis of the first stationary gear as the axis.

[0045] The drive gear component 3 includes a drive gear component gear 31 and a drive gear component disk 32. The drive gear component disk 32 is a vertically arranged disc structure; the drive gear component gear 31 coaxially passes through the drive gear component disk 32; the portion of the drive gear component gear 31 located outside the drive gear component disk 32 is a gear structure; the portion of the drive gear component gear 31 located inside the drive gear component disk 32 is a rocker arm structure; the gear structure and the rocker arm structure are fixedly connected.

[0046] The drive gear component 3 mainly includes a drive gear component gear 31 and a drive gear component disc 32. One side of the drive gear component gear 31 has a gear with a certain number of teeth, and the other side has a protruding rocker arm structure. The gear axis on the drive gear component gear 31 is coaxial with the disc axis of the drive gear component disc 32, and the two parts are fixedly connected.

[0047] The drive gear component 3 meshes with the first stationary gear through the gear structure of the drive gear component gear 31; the gear structure drives the rocker arm structure to rotate synchronously.

[0048] The transmission gear connecting rod assembly 4 includes a transmission gear connecting rod gear 41 and a transmission gear connecting rod 42. One end of the transmission gear connecting rod 42 is mounted on a fixed shaft 23; the transmission gear connecting rod gear 41 is fixedly mounted on the side wall of the transmission gear connecting rod 42; the transmission gear connecting rod gear 41 meshes with a second stationary gear; the rotation of the transmission gear connecting rod gear 41 drives the transmission gear connecting rod 42 to rotate; the other end of the transmission gear connecting rod 42 is rotatably connected to the lower leg structure assembly 6.

[0049] The rotating link component 5 includes a rotating link 51; the rotating link 51 has two docking holes at both ends; one docking hole docks with the rocker arm structure of the drive gear component 31; the other docking hole docks with the lower leg structure component 6.

[0050] The lower leg structure component 6 includes a lower leg structure 61; the lower leg structure 61 is designed with a swing connecting shaft and a rotary connecting shaft; the swing connecting shaft is located above the rotary connecting shaft; the swing connecting shaft is connected to the other end of the transmission gear connecting rod 42; the rotary connecting shaft is connected to another connecting hole of the rotary connecting rod component 5.

[0051] The movement process of the knee joint mechanism is as follows:

[0052] The first stationary gear at the bottom of the inner main structure 11 meshes with the gear on the drive gear component 31, forming a gear transmission pair through the gear connecting rod component 2; when the drive gear component wheel 32 is driven to rotate externally, the gear connecting rod component 2 rotates around the gear shaft at the joint of the inner main structure 11 and the outer gear structure 12, the drive gear component gear 31 rotates around the fixed shaft 23, and the rotation axis of the drive gear component gear 31 protruding from the rocker arm structure rotates around the fixed shaft 23.

[0053] When the gear connecting rod assembly 2 rotates around the gear shaft at the joint between the inner main body structure 11 and the outer gear structure 12, the other end hole shaft of the transmission gear connecting rod 42 rotates around the fixed shaft 23.

[0054] The other end of the transmission gear connecting rod 42 is connected to the swing connecting shaft of the lower leg structure 61 via a rotary joint, so that when the other end of the transmission gear connecting rod 42 rotates around the fixed shaft 23, the swing connecting shaft 61 of the lower leg structure component moves in the plane, thereby realizing the translation of the lower leg structure component 6 relative to the thigh structure component 1.

[0055] One end of the rotating link 51 is connected to the rotating shaft of the drive gear component 31 protruding from the rocker arm structure via a rotating pair; the other end of the rotating link 51 is connected to the rotating connecting shaft of the lower leg structure 61 via a rotating pair, so that when the rotating shaft of the drive gear component 31 protruding from the rocker arm structure rotates around the fixed shaft 23, the rotating connecting shaft of the lower leg structure component 61 rotates around the swing connecting shaft of the lower leg structure component 6, thereby realizing the rotation of the lower leg structure component 6.

[0056] The multi-link double-tooth meshing mechanism proposed in this invention achieves high-precision matching between the mechanism and the instantaneous center of motion of the human knee joint through the design of gear and link parameters, with a maximum error of less than 0.7mm. This invention employs a gear and link transmission combination, resulting in a mechanism with 1 degree of freedom and stable motion when driven by external power. The transmission link eliminates springs, ropes, and other components, resulting in high transmission stiffness. It allows for a wide range of motion in the calf and thigh, covering the entire range of human movement.

[0057] This invention employs two sets of gears connected in parallel, one inside and one outside, to jointly bear the joint load. This helps reduce the gear module, resulting in a compact mechanism suitable for various applications. The invention integrates an external drive interface structure within the two sets of parallel gears, adapting to both direct drive and remote drive methods.

[0058] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A bionic knee joint mechanism for robots, characterized in that: It includes a thigh structure component (1), a gear and connecting rod component (2), a drive gear component (3), a transmission gear and connecting rod component (4), a rotating connecting rod component (5), and a lower leg structure component (6); The thigh structure component (1) is placed vertically; the gear connecting rod component (2) is installed at the bottom of the thigh structure component (1); the drive gear component (3) and the transmission gear connecting rod component (4) are both based on the gear connecting rod component (2); the transmission gear connecting rod component (4) meshes with the thigh structure component (1); the drive gear component (3) meshes with the thigh structure component (1); the top of the calf structure component (6) is connected to the transmission gear connecting rod component (4); the calf structure component (6) is driven to translate relative to the thigh structure component (1) through the meshing and rotation of the transmission gear connecting rod component (4) and the thigh structure component (1); one end of the rotating connecting rod component (5) is connected to the drive gear component (3), and the other end of the rotating connecting rod component (5) is connected to the middle of the calf structure component (6); the drive gear component (3) meshes with the thigh structure component (1) and rotates, driving the calf structure component (6) to rotate relative to the thigh structure component (1) through the rotating connecting rod component (5).

2. The bionic knee joint mechanism for robots according to claim 1, characterized in that: The thigh structure component (1) includes an inner main structure (11), an outer gear structure (12), and a connecting structure (13); Among them, the inner main structure (11) is a vertically arranged plate structure; a first stationary gear is provided at the bottom of the inner main structure (11); the top of the connecting structure (13) is installed in the middle of the inner main structure (11); a second stationary gear is provided at the bottom of the connecting structure (13); the first stationary gear and the second stationary gear are coaxial.

3. The bionic knee joint mechanism for robots according to claim 2, characterized in that: The gear connecting rod assembly (2) includes an outer connecting rod (21), an inner connecting rod (22), and a fixed shaft (23); The outer connecting rod (21) and the inner connecting rod (22) are arranged in parallel; the fixed shaft (23) is installed vertically between the outer connecting rod (21) and the inner connecting rod (22), and is located at the outer end of the outer connecting rod (21) and the inner connecting rod (22), forming a U-shaped structure.

4. The bionic knee joint mechanism for robots according to claim 3, characterized in that: The thigh structure component (1) extends into the opening end of the U-shaped structure; the inner ends of the outer connecting rod (21) and the inner connecting rod (22) are coaxially connected with the first stationary gear and the second stationary gear; thus realizing that the gear connecting rod component (2) rotates relative to the thigh structure component (1) with the shaft of the first stationary gear as the axis.

5. The bionic knee joint mechanism for robots according to claim 3, characterized in that: The drive gear component (3) includes a drive gear component gear (31) and a drive gear component disc (32); Among them, the drive gear component disk (32) is a vertically arranged disk structure; the drive gear component gear (31) coaxially passes through the drive gear component disk (32); the part of the drive gear component gear (31) located outside the drive gear component disk (32) is a gear structure; the part of the drive gear component gear (31) located inside the drive gear component disk (32) is a rocker arm structure; the gear structure and the rocker arm structure are fixedly connected.

6. The bionic knee joint mechanism for robots according to claim 5, characterized in that: The drive gear component (3) meshes with the first stationary gear through the gear structure of the drive gear component gear (31); the gear structure drives the rocker arm structure to rotate synchronously.

7. A bionic knee joint mechanism for robots according to claim 5, characterized in that: The transmission gear connecting rod component (4) includes a transmission gear connecting rod component gear (41) and a transmission gear connecting rod (42); One end of the transmission gear connecting rod (42) is mounted on the fixed shaft (23); the transmission gear connecting rod component gear (41) is fixedly installed on the side wall of the transmission gear connecting rod (42); the transmission gear connecting rod component gear (41) meshes with the second stationary gear; the transmission gear connecting rod component gear (41) rotates through meshing, driving the transmission gear connecting rod (42) to rotate; the other end of the transmission gear connecting rod (42) is rotatably connected to the lower leg structure component (6).

8. The bionic knee joint mechanism for robots according to claim 7, characterized in that: The rotating link component (5) includes a rotating link (51); the two ends of the rotating link (51) are provided with two docking holes; one docking hole is docked with the rocker arm structure of the drive gear component (31); the other docking hole is docked with the lower leg structure component (6).

9. A bionic knee joint mechanism for robots according to claim 8, characterized in that: The lower leg structure component (6) includes a lower leg structure (61); the lower leg structure (61) is designed with a swing connecting shaft and a rotary connecting shaft; the swing connecting shaft is located above the rotary connecting shaft; the swing connecting shaft is connected to the other end of the transmission gear connecting rod (42); the rotary connecting shaft is connected to another docking hole of the rotary connecting rod component (5).

10. A bionic knee joint mechanism for robots according to claim 9, characterized in that: The movement process of the knee joint mechanism is as follows: The first stationary gear at the bottom of the inner main structure (11) meshes with the gear on the drive gear component (31), forming a gear transmission pair through the gear connecting rod component (2); when the drive gear component wheel (32) is driven to rotate externally, the gear connecting rod component (2) rotates around the gear shaft at the joint of the inner main structure (11) and the outer gear structure (12), the drive gear component gear (31) rotates around the fixed shaft (23), and the rotation axis of the drive gear component gear (31) protruding from the rocker arm structure rotates around the fixed shaft (23); When the gear connecting rod component (2) rotates around the gear shaft at the joint of the inner main body structure (11) and the outer gear structure (12), the other end hole shaft of the transmission gear connecting rod (42) rotates around the fixed shaft (23); The other end of the transmission gear connecting rod (42) is connected to the swing connecting shaft of the lower leg structure (61) via a rotary joint, so that when the other end of the transmission gear connecting rod (42) rotates around the fixed shaft (23), the swing connecting shaft of the lower leg structure component moves in the plane, thereby realizing the translation of the lower leg structure component (6) relative to the thigh structure component (1). One end of the rotating connecting rod (51) is connected to the rotating shaft of the drive gear component (31) protruding from the rocker arm structure. The other end of the rotating link (51) is connected to the rotating connection shaft of the lower leg structure (61) via a rotating pair. When the rotating shaft of the drive gear component (31) protruding from the rocker arm structure rotates around the fixed shaft (23), the rotating connection shaft of the lower leg structure component (6) rotates around the swing connection shaft of the lower leg structure component (6), thus realizing the rotation of the lower leg structure component (6).

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