Knee joint structure, knee joint movement method and mechanical leg

Abstract

The invention belongs to the field of mechanical legs, and particularly relates to a knee joint structure, a knee joint movement method and a mechanical leg, and the knee joint structure comprises a four-bar mechanism and a rotating wheel mechanism; the four-connecting-rod mechanism comprises a connecting rod I, a connecting rod II, a connecting rod III and a connecting rod IV which are sequentially hinged end to end, the connecting rod I is used for connecting thighs of the mechanical legs, and the connecting rod III is used for connecting shanks of the mechanical legs; the rotating wheel mechanism comprises a connecting rod V and a connecting rod VI which are hinged to each other, a transmission wheel I is rotationally arranged on the hinged axis of the connecting rod V and the connecting rod VI, a driving wheel / driven wheel rotationally matched with the transmission wheel I is rotationally arranged on the connecting rod V, and the driving wheel / driven wheel is rotationally arranged on the connecting rod I; the connecting rod VI is rotationally provided with a driven / driving wheel rotationally matched with the transmission wheel I. The driven / driving wheel is rotationally arranged on the connecting rod III. According to the invention, excellent optimization effects are embodied in the aspects of passive motion stability, structural bearing capacity and module redundancy design.

Description

Technical Field

[0001] The present invention belongs to the field of mechanical legs, and in particular relates to a knee joint structure, a knee joint movement method and a mechanical leg. Background Art

[0002] One of the core goals of the development of technology fields such as knee prostheses or powered exoskeletons is to simulate the natural, stable and efficient biomechanical properties of the human knee. A healthy knee exhibits a complex trajectory of the instantaneous center of rotation (instant center) during flexion and extension, which is essential for achieving a smooth and stable gait. At the same time, such devices must not only be able to work under active power drive, but also have intrinsic stability, impact resistance and load-bearing reliability when power is interrupted (such as power failure, system failure) or passively moves under external impact (such as being pushed or swung by external force), which is crucial to the safety of the user and the practicality of the device.

[0003] At present, there are mainly the following ways to design mechanisms to simulate knee joint motion: 1. Pure hinge or simple uniaxial hinge: The structure is the simplest, but the instantaneous center trajectory is very different from that of a healthy knee joint, resulting in an unnatural gait, low energy efficiency, and a lack of constraints on complex movements in a passive state, making it easy to shake or produce uncontrolled displacement.

[0004] 2. Four-bar linkage: It is a significant improvement over the single-axis hinge. It can simulate the instantaneous center trajectory closer to the human body, improve the naturalness of movement, and provide better internal structural stability and load-bearing capacity. However, the traditional four-bar linkage still has limitations in the fitting accuracy and flexibility of the instantaneous center trajectory. Although its passive stability is better than that of a single axis, the movement coordination inside the joint cannot be compared with a complex structure with motion constraints. The simple passive four-bar linkage still has room for improvement in terms of movement smoothness and anti-shake.

[0005] 3. Bionic knee joint structure based on five-link three-gear: (such as Chinese invention patent CN103976807B - "A prosthetic knee joint with a gear five-bar mechanism"). This type of design attempts to accurately control the instantaneous center trajectory and the relative motion angle between the links through additional links and gear constraint mechanisms. However, this type of structure has exposed a series of key problems in practice, especially the challenges in equipment safety and robustness. For example, the high degree of integration of this type of mechanism is both its advantage and disadvantage. When the active power drive fails or disconnects, the system exposes its inherent fragility. At certain specific angles, complex rod systems are prone to fall into mechanical dead points. In the active drive state, it can be overcome by inertia or driving force; but in passive movements with less inertia (such as slow swinging of the calf by external force), the system is more likely to get stuck near the dead point, resulting in discontinuous movement or even complete jamming.

[0006] In summary, the existing technologies, especially the five-link three-gear mechanism, have obvious deficiencies in terms of stability in the passive state (resistance to jamming, suppression of wobbling, maintenance of a definite trajectory), impact resistance, ultimate load-bearing capacity, and modular system robustness and redundant design. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a knee joint structure, a knee joint movement method, and a mechanical leg that exhibit excellent optimization effects in terms of passive movement stability, structural load-bearing capacity, and modular redundancy design.

[0008] The present invention provides a knee joint structure, including a four-link mechanism and a rotating wheel mechanism; The four-link mechanism includes link Ⅰ, link Ⅱ, link Ⅲ, and link Ⅳ that are sequentially hinged end to end, where link Ⅰ is used to connect the thigh of the mechanical leg, and link Ⅲ is used to connect the calf of the mechanical leg; The rotating wheel mechanism includes link Ⅴ and link Ⅵ that are hinged to each other. A transmission wheel Ⅰ is rotatably arranged on the hinge axis of link Ⅴ and link Ⅵ. A main / slave wheel that is rotationally matched with the transmission wheel Ⅰ is rotatably arranged on link Ⅴ. The main / slave wheel is rotatably arranged on link Ⅰ. A slave / active wheel that is rotationally matched with the transmission wheel Ⅰ is rotatably arranged on link Ⅵ. The slave / active wheel is rotatably arranged on link Ⅲ.

[0009] Furthermore, a connecting rod is arranged on link Ⅲ. The connecting rod includes connecting rod Ⅰ, connecting rod Ⅱ, and connecting rod Ⅲ that are sequentially connected; Connecting rod Ⅰ and connecting rod Ⅲ are parallel to each other, and one end of connecting rod Ⅰ is fixed on link Ⅲ; The slave / active wheel is rotatably arranged at the end of connecting rod Ⅲ.

[0010] Furthermore, the projection of the axis of the slave / active wheel onto the plane of the four-link mechanism is located on link Ⅲ.

[0011] Furthermore, connecting rod Ⅰ is coplanar with the plane of the four-link mechanism, and the slave / active wheel is located between connecting rod Ⅰ and connecting rod Ⅱ.

[0012] Furthermore, the transmission wheel Ⅰ, the main / slave wheel, and the slave / active wheel are located between the four-link mechanism and link Ⅴ and link Ⅵ.

[0013] Furthermore, the rotation axis of the main / slave wheel is coaxial with the hinge axis of link Ⅰ and link Ⅱ.

[0014] Furthermore, the length of link Ⅰ is 27 mm, the length of link Ⅱ is 80 mm, the length of link Ⅲ is 45 mm, and the length of link Ⅳ is 45 mm.

[0015] Furthermore, the transmission ratio of the master / slave wheel and the slave / master wheel is 1.

[0016] The present invention also provides a knee joint movement method, which uses the above knee joint structure and includes active knee joint movement and passive knee joint movement; The active knee joint movement includes the following steps: Power output drives the master / slave wheel or the slave / master wheel to rotate, and the master / slave wheel or the slave / master wheel drives the slave / master wheel or the master / slave wheel to rotate through transmission wheel I; Meanwhile, the four-bar linkage mechanism and the rotating wheel mechanism move in coordination, enabling the four-bar linkage mechanism to perform a specific trajectory movement; The passive knee joint movement includes the following steps: Link I or link III moves passively and coordinates with the rotating wheel mechanism during the passive movement, enabling the four-bar linkage mechanism to perform a specific trajectory movement.

[0017] The present invention also provides a mechanical leg, which includes the above knee joint structure.

[0018] The beneficial effects of the present invention are as follows. In the present invention, the four-bar linkage mechanism in the knee joint structure is equivalent to a structurally stable main chain, while the rotating wheel mechanism is equivalent to a speed coordination sub-chain. It not only achieves or even exceeds the knee joint structure formed by the traditional five-bar linkage and three-gear structure in terms of movement coordination, but also shows excellent optimization effects in terms of passive movement stability, structural load-bearing capacity, and module redundancy design. In contrast, the traditional five-bar linkage and three-gear structure appears single and fragile in the power interruption state, and its force is mainly borne by the three gears. The concentrated load borne by the three gears is more likely to fail during long-term use or external impact, reducing the safety and reliability of the system.

[0019] For the knee joint structure provided by the present invention, after the active force is disconnected, the four-bar linkage mechanism and the rotating wheel mechanism still maintain a synchronous coupling movement relationship, and the system can autonomously maintain the passive movement trajectory; it has better stability, anti-jitter ability, and load balance in the passive state, and is suitable for scenarios with high robustness requirements.

[0020] Therefore, the four-bar linkage mechanism of the present invention itself constitutes a closed load-bearing path, having natural structural stability. The two-link + three-gear system in the rotating wheel mechanism plays a role in angular velocity constraint, torque transmission, and trajectory fine-tuning in the structure. After the two are combined, the load transmission path is shared by multiple paths, significantly improving the anti-impact ability and ultimate load-bearing capacity of the overall structure. After the active force is disconnected, it can rely on the coupling of the four-bar linkage mechanism and the rotating wheel mechanism to achieve stable passive gait simulation, which is significantly better than the mechanical instability problem of the five-bar linkage mechanism under power-off conditions.

[0021] In addition, in a traditional gear four-bar linkage mechanism, two or three gears are directly rotatably arranged on two or three hinge axes of the four-bar linkage mechanism. When applied to the knee joint, its essence is no different from that of a traditional five-bar three-gear structure. However, this knee joint structure is optimized for the application scenario of the knee joint. In the rotating wheel mechanism, the main / driven wheel and the driven / active wheel do not have to be installed on the hinge axis of the four-bar linkage mechanism, and the axis of the transmission wheel I is independent of the four-bar linkage mechanism, enabling it to be coupled and constrained with the four-bar linkage mechanism, achieving excellent kinematic coordination, high impact resistance, and ultimate load-bearing capacity of the knee joint structure.

[0022] By designing the dimensions of the four-bar linkage mechanism and the rotating wheel mechanism, a customized trajectory can be achieved, generating a complex curve that highly coincides with the instantaneous center trajectory of a healthy knee joint and can be dynamically adjusted, exceeding the fitting ability of a pure four-bar mechanism. Ultimately, the gait becomes more natural and efficient, and the adaptability to different terrains such as slopes and stairs is stronger. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG Figure 1 is a schematic structural view of the knee joint system of the present invention from a first angle; FIG Figure 2 is a schematic structural view of the knee joint system of the present invention from a second angle; FIG Figure 3 is a schematic structural view of the knee joint structure of the present invention from a first angle; FIG Figure 4 is a schematic structural view of the knee joint structure of the present invention from a second angle; FIG Figure 5 is a front view of the knee joint structure of the present invention at the initial angle; FIG Figure 6 is a front view of the knee joint structure of the present invention at an intermediate angle; FIG Figure 7 is a front view of the knee joint structure of the present invention at the extreme flexion angle; FIG Figure 8 is a schematic dimension view of the four-bar linkage mechanism in one embodiment of the present invention; FIG Figure 9 is a schematic motion view of the four-bar linkage mechanism of the present invention; FIG Figure 10 is a motion curve graph of the four-bar linkage mechanism of the present invention; FIG Figure 11 is a schematic cooperation view of the main-passive switching structure and the rotary drive mechanism of the present invention; FIG Figure 12 is a schematic structural view of the main-passive switching structure of the present invention; FIG Figure 13 is a schematic structural view of the main-passive switching structure when the driving wheel and the driven wheel are connected; FIGFigure 14 This is a schematic diagram of the structure when the driving wheel and the driven wheel in the active-passive switching structure of the present invention are separated.

[0024] In the figure, 1 is a four-bar linkage mechanism; 11 is link I; 12 is link II; 13 is link III; 14 is link IV; 15 is connecting rod I; 16 is connecting rod II; 17 is connecting rod III; 2 is a rotating wheel mechanism; 21 is link V; 22 is link VI; 23 is driving wheel I; 24 is the main / driven wheel; 25 is the driven / driving wheel; 3 is the active-passive switching structure; 31 is the driving wheel; 32 is driving wheel II; 33 is the driven wheel; 34 is the bracket; 35 is the rotating part; 36 is the clutch rod; 37 is the chute plate; 371 is the arc chute; 38 is the elastic part; 39 is the locking connecting rod; 310 is the slider; 311 is the rotating rod; 312 is the manual operating rod; 4 is the rotary drive mechanism; 41 is the motor; 42 is the gear set; 43 is the bevel gear set. Specific embodiments

[0025] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0026] It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the present invention are only used to explain the relative position relationship and movement conditions between components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0027] In addition, the descriptions such as "first" and "second" in the present invention are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, "a plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0028] In the present invention, unless otherwise clearly defined and limited, terms such as "connection" and "fixation" shall be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can be directly connected, or indirectly connected through an intermediate medium, and can be the communication inside two components or the interaction relationship between two components, unless otherwise clearly defined. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] In addition, the technical solutions between various embodiments of the present invention can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0030] As shown in the attached Figure 1 - attached Figure 14 figure, the present invention provides a knee joint structure, including a four-bar linkage mechanism 1 and a rotating wheel mechanism 2; The four-bar linkage mechanism 1 includes a link Ⅰ 11, a link Ⅱ 12, a link Ⅲ 13, and a link Ⅳ 14 that are sequentially hinged end to end. Among them, the link Ⅰ 11 is used to connect the thigh of the mechanical leg, and the link Ⅲ 13 is used to connect the calf of the mechanical leg. That is, two opposite links in the four-bar linkage mechanism are respectively used to connect the thigh and calf of the mechanical leg; The rotating wheel mechanism 2 includes a link Ⅴ 21 and a link Ⅵ 22 that are hinged to each other. A driving wheel Ⅰ 23 is rotatably arranged on the hinge axis of the link Ⅴ 21 and the link Ⅵ 22. A main / driven wheel 24 that rotates in cooperation with the driving wheel Ⅰ 23 is rotatably arranged on the link Ⅴ 21. The main / driven wheel 24 is rotatably arranged on the link Ⅰ 11. A driven / active wheel 25 that rotates in cooperation with the driving wheel Ⅰ 23 is rotatably arranged on the link Ⅵ 22. The driven / active wheel 25 is rotatably arranged on the link Ⅲ 13. That is, the main / driven wheel 24, the driving wheel Ⅰ 23, and the driven / active wheel 25 are sequentially meshed, and the movement trajectories are simultaneously restricted by the link Ⅴ 21, the link Ⅵ 22, and the four-bar linkage mechanism 1. The main / driven wheel 24 can be used as the driving wheel. At this time, the driven / active wheel 25 is the driven wheel. On the contrary, the main / driven wheel 24 can be used as the driven wheel. At this time, the driven / active wheel 25 is the driving wheel. The driving wheel can be used to connect with the rotary drive mechanism 4, and then actively drive the driving wheel Ⅰ 23 and the driven wheel to rotate, driving the four-bar linkage mechanism 1 to move along its specific movement trajectory. The driving wheel can also be separated from the rotary drive mechanism 4. At this time, the main / driven wheel 24, the driving wheel Ⅰ 23, and the driven / active wheel 25 will all be driven to rotate passively due to the deformation of the four-bar linkage mechanism 1. Both the main / driven wheel 24 and the driven / active wheel 25 are both the driving wheel and the driven wheel.

[0031] In the present invention, the four-bar linkage mechanism 1 in the knee joint structure is equivalent to the main chain with stable structure, and the rotating wheel mechanism 2 is equivalent to the speed coordination sub-chain. It can not only achieve or even exceed the knee joint structure formed by the traditional five-bar three-gear structure in terms of motion coordination (Chinese invention patent CN103976807B - A prosthetic knee joint with a gear five-bar mechanism), but also shows excellent optimization effects in terms of passive motion stability, structural bearing capacity and module redundancy design. In contrast, the traditional five-bar three-gear structure appears to be single and fragile in the power interruption state. Its force is mainly borne by the three gears, and the concentrated load borne by the three gears is more likely to fail during long-term use or external impact, reducing the safety and reliability of the system.

[0032] Specifically, after the power system of the traditional five-bar three-gear structure fails or disconnects, its structure has the following problems due to: a large number of single-system connecting rods (the six connecting rods in the present invention are divided into a four-bar system and a two-bar system, a total of two independent systems), high degrees of freedom; a large number of hinge points and an increase in friction pairs; the lack of a stabilizing component for structural position constraint: dead point jamming phenomenon: the multi-bar system is prone to getting stuck in the mechanical dead point at some angles and lacks inertia to pass through. Since the passive motion has lower inertia than the active motion, the traditional five-bar three-gear structure is more likely to have the dead point jamming phenomenon; instability and swaying: redundant degrees of freedom, unable to stably maintain the relative angles of the connecting rods after losing active control, resulting in loose or swinging structure; path uncertainty: since the motion trajectory depends on the active force drive and there is no passive trajectory guidance or closed-loop constraint; high risk of user imbalance: when the user swings only by external force, the control force is insufficient, and there is a risk of falling due to the lack of restraint of the structure. However, for the knee joint structure provided by the present invention, after the active force is disconnected, the four-bar linkage mechanism 1 and the rotating wheel mechanism 2 still maintain a synchronous coupling motion relationship, and the system can autonomously maintain the passive motion trajectory; the stability, anti-shaking ability and load balance in the passive state are better, which is suitable for scenarios with high robustness requirements (such as walking without power, anti-falling, etc.).

[0033] Therefore, the four-bar linkage mechanism 1 of the present invention itself constitutes a closed load-bearing path, with natural structural stability. The two-link + three-gear system in the rotating wheel mechanism 2 plays a role in angular velocity constraint, torque transmission and trajectory fine-tuning in the structure. After the two are combined, the load transfer path is shared by multiple paths, significantly improving the anti-impact ability and ultimate bearing capacity of the overall structure. After the active force is disconnected, it can rely on the coupling of the four-bar linkage mechanism 1 and the rotating wheel mechanism 2 to achieve stable passive gait simulation, which is significantly better than the mechanical instability problem of the five-bar mechanism under power-off conditions.

[0034] In addition, in a traditional gear four-bar linkage mechanism, two or three gears are directly rotatably arranged on two or three hinge axes of the four-bar linkage mechanism. When applied to the knee joint, its essence is no different from that of a traditional five-bar three-gear structure. However, this knee joint structure is optimized for the application scenario of the knee joint. In the rotation wheel mechanism 2, the main / driven wheel 24 and the driven / active wheel 25 do not have to be installed on the hinge axis of the four-bar linkage mechanism 1, and the axis of the transmission wheel I 23 is independent of the four-bar linkage mechanism 1, enabling it to be coupled with and constrained by the four-bar linkage mechanism 1, achieving excellent kinematic coordination, high impact resistance, and ultimate load-bearing capacity of the knee joint structure.

[0035] By designing the dimensions of the four-bar linkage mechanism 1 and the rotation wheel mechanism 2, referring to Figures 8 - 10 , a customized trajectory can be achieved, generating a complex curve that highly coincides with the instantaneous center trajectory of a healthy knee joint and can be dynamically adjusted, exceeding the fitting ability of a pure four-bar mechanism. Ultimately, the gait becomes more natural and efficient, and the adaptability to different terrains such as slopes and stairs is stronger.

[0036] It should be noted that in this application, the main / driven wheel 24, the transmission wheel I 23, and the driven / active wheel 25 are preferably gears. However, due to the coupling of the four-bar linkage mechanism 1 and the rotation wheel mechanism 2 to achieve stable passive gait simulation, friction wheels can also be used.

[0037] In one embodiment, a connecting rod is provided on the link III 13, and the connecting rod includes a connecting rod I 15, a connecting rod II 16, and a connecting rod III 17 connected in sequence; The connecting rod I 15 and the connecting rod III 17 are parallel to each other, and one end of the connecting rod I 15 is fixed on the link III 13; The driven / active wheel 25 is rotatably arranged at the end of the connecting rod III 17.

[0038] In this embodiment, by setting the connecting rod, on the one hand, the calf of the robotic leg can be connected through the connecting rod I 15 or the connecting rod III 17, so that the connection position of the calf is relatively far from the four links in the four-bar linkage mechanism 1, avoiding the compact area, ensuring the movement range of the four-bar linkage mechanism 1, and facilitating the connection with the driven / active wheel 25. On the other hand, the setting of the connecting rod can extend the force arm and improve the torque transmission efficiency.

[0039] In a preferred embodiment, the end of the connecting rod III 17 is hinged to the end of the link VI 22, thereby realizing the connection between the four links in the four-bar linkage mechanism 1 and the two links in the rotation wheel mechanism 2, greatly improving the load transfer path of the overall structure, enhancing the load capacity, and at the same time improving the structural stability of the overall structure.

[0040] In one embodiment, the projection of the axis of the slave / driving wheel 25 to the plane of the four-bar linkage 1 is located on the connecting rod III 13. This arrangement can make the motion trajectory of the slave / driving wheel 25 completely equivalent to when it is directly rotated on the connecting rod III 13, without affecting the coupling of the four-bar linkage 1 and the rotating wheel mechanism 2.

[0041] In one embodiment, the connecting rod Ⅰ15 is coplanar with the plane of the four-bar linkage 1, and the slave / driving wheel 25 is located between the connecting rod Ⅰ15 and the connecting rod Ⅱ16. Such a configuration can stably and reliably fix the slave / driving wheel 25. The two rigid rods of the connecting rod Ⅰ15 and the connecting rod Ⅱ16 can constitute a protective bracket for the slave / driving wheel 25. Preferably, the slave / driving wheel 25 can be connected to the ends of the connecting rod Ⅰ15 and the connecting rod Ⅱ16 away from the connecting rod Ⅲ13 at the same time, or the slave / driving wheel 25 can be connected to the connecting rod Ⅱ16 and the connecting rod Ⅲ13 at the same time, so that the slave / driving wheel 25 is a double-point fixed structure, which greatly improves the rotation stability of the slave / driving wheel 25.

[0042] In one embodiment, the transmission wheel I 23 , the master / slave wheel 24 and the slave / driving wheel 25 are located between the four-bar linkage 1 and the connecting rods V 21 and VI 22 .

[0043] In this embodiment, the three wheels are located between the two groups of rods, so that the overall structure is compact, and the two groups of rods constitute physical protection for the wheels.

[0044] In one embodiment, the rotation axis of the driving / driven wheel 24 is coaxial with the articulation axis of the connecting rod Ⅰ11 and the connecting rod Ⅱ12.

[0045] This setting not only ensures that the connecting rod rotation and gear drive are completely synchronized, improving motion consistency and transmission efficiency, but also greatly simplifies the structure, shortens the torque transmission path, better resists knee bending and deflection torque, and enhances structural rigidity and stability. Especially in passive mode, the structure can stably respond to external force drive to avoid swing out of control or load transmission imbalance.

[0046] In one embodiment, the length of the connecting rod I 11 is 27 mm, the length of the connecting rod II 12 is 80 mm, the length of the connecting rod III 13 is 45 mm, and the length of the connecting rod IV 14 is 45 mm. Figures 3 - 10, after the four-bar linkage 1 is coupled with the rotating wheel mechanism 2, a specific motion trajectory can be achieved. The main / driven wheel 24 at the hinge axis of the link Ⅰ11 and the link Ⅱ12 is used as the driving wheel to simulate the motion trajectory curve. It can be found that the relative distance in the relative motion between the link Ⅰ11 and the link Ⅲ13 changes and does not show a linear law. Such a setting is not only closer to the "rolling + sliding" composite trajectory of the human knee joint during flexion and extension, but also can achieve non-uniform torque transmission by controlling the gear ratio and transmission structure. The auxiliary intelligent control system can be adjusted more precisely to improve the human-machine interaction performance of the prosthetic limb. The results are as Figure 9 and Figure 10 ( Figure 10 In Figure 10 , A is the hinge axis of the link Ⅲ13 and the link Ⅳ14, B is the connection point of the connecting rod Ⅰ15 and the connecting rod Ⅱ16, and C is the hinge point of the link Ⅰ11 and the link Ⅱ12). That is, the four-bar linkage 1 cooperates with the rotating wheel mechanism 2, and can maintain stable power transmission at any position, and will not slip or change due to the change of distance, etc., and can realize stable power output. Finally, a more natural and adaptable gait is achieved. During the whole process of motion, there will be no motion interference between the components, the motion is smooth, and there are no dead points, speed mutations, and angle mutations.

[0047] In one embodiment, the transmission ratio of the main / driven wheel 24 and the driven / driving wheel 25 is 1. With such a setting, in the passive mode, the transmission ratio of the gear train is 1. Since both the main / driven wheel 24 and the driven / driving wheel 25 are free rotating shafts and there is no external load, this structure can be reversely driven in the passive mode, ensuring the availability of the passive mode.

[0048] The present invention also provides a knee joint motion method, using the above knee joint structure, including active knee joint motion and passive knee joint motion; The active knee joint motion includes the following steps: Power output drives the main / driven wheel 24 or the driven / driving wheel 25 to rotate, and the main / driven wheel 24 or the driven / driving wheel 25 drives the driven / driving wheel 25 or the main / driven wheel 24 to rotate through the transmission wheel Ⅰ23; At the same time, the four-bar linkage 1 and the rotating wheel mechanism 2 move in coordination, so that the four-bar linkage 1 performs a motion with a specific trajectory; The passive knee joint motion includes the following steps: The link Ⅰ11 or the link Ⅲ13 moves passively, and during the passive movement, it cooperates with the rotating wheel mechanism 2, so that the four-bar linkage 1 performs a motion with a specific trajectory.

[0049] The present invention also provides a mechanical leg, and the mechanical leg includes the above knee joint structure. The mechanical leg is preferably a prosthetic limb, and thus realizes passive motion under the movement of the human body. It can also be an exoskeleton structure of the human leg.

[0050] The present invention also provides a main - passive switching structure 3, which includes a driving wheel 31, a transmission wheel II 32, a driven wheel 33, a bracket 34 and a clutch mechanism; The driving wheel 31 and the driven wheel 33 are rotatably arranged on the bracket 34. The driving wheel 31 is used to connect with a rotary driving mechanism 4, so as to realize the driving rotation of the driving wheel 31 and the active movement of the knee joint structure. The driven wheel 33 is used to connect with the driving part of the knee joint structure, that is, the main / driven wheel 24 or the driven / active wheel 25 of the knee joint structure. Figure 1 For the driven wheel 33 to connect with the driven / active wheel 25; The clutch mechanism includes an operating part and a locking part. The operating part includes a rotating part 35 rotatably arranged on the axis of the driving wheel 31, and a clutch rod 36 fixedly arranged on the rotating part 35. The transmission wheel II 32 is rotatably arranged on the clutch rod 36, and the transmission wheel II 32 is always in rotational cooperation with the driving wheel 31. By rotating the clutch rod 36, the transmission wheel II 32 is brought into rotational cooperation or separation with the driven wheel 33. Refer to Figure 13 , when the transmission wheel II 32 is in rotational cooperation with the driven wheel 33, the driving wheel 31, the transmission wheel II 32 and the driven wheel 33 are in rotational cooperation in sequence, so as to realize the rotational cooperation between the driving wheel 31 and the driven wheel 33. Refer to Figure 14 , when the transmission wheel II 32 is separated from the driven wheel 33, the driving wheel 31 and the driven wheel 33 are disconnected from rotational cooperation. At this time, the driven wheel 33 loses the load and becomes a free structure with the main / driven wheel 24 or the driven / active wheel 25 of the knee joint structure, realizing the passive movement of the four - bar mechanism 1 and the rotating wheel mechanism 2 in the knee joint structure.

[0051] The locking part is used to lock the position of the clutch rod 36, maintaining the rotational cooperation state or separation state between the transmission wheel II 32 and the driven wheel 33, thereby realizing high stability of the active movement and the passive movement.

[0052] This main - passive switching structure 3 is used to realize the rapid switching between the active and passive movements of the knee joint structure. After the rotary driving mechanism 4 of the mechanical leg loses power, the knee joint structure can be switched to the passive movement state, so that it can still be used as a passive mechanical leg (such as a prosthetic limb). The knee joint structure is in the form of a combination of a main - passive dual system.

[0053] In the active mode, high - precision and stable power transmission is realized by relying on the transmission wheel (gear). In the passive mode, it can be driven in reverse without affecting the movement of the four - bar mechanism 1 in the knee joint structure, forming a complete knee joint transmission chain.

[0054] By coupling the active-passive switching structure 3 of the present invention with the knee joint structure, the mechanical leg (prosthesis) can still be used as a four-bar passive mechanical leg (prosthesis) after the electric energy is exhausted, reducing the dependence on electric energy. At the same time, it can actively switch states according to different usage scenarios, save electric energy usage, and adapt to more scenarios. It enables the more reassuring use of the mechanical leg (prosthesis) without causing range anxiety, thereby improving the suitability.

[0055] In one embodiment, the locking portion includes a chute plate 37, an elastic member 38, and a locking connecting rod 39; The chute plate 37 is relatively fixed to the bracket 34. An arc chute 371 is provided on the chute plate 37. A slider 310 is slidably disposed on the arc chute 371. The convex side of the arc chute 371 faces the axis of the driving wheel 31; One end of the locking connecting rod 39 is fixed to the rotating member 35, and the other end intersects the arc chute 371 and is located on the concave side of the arc chute 371; One end of the elastic member 38 is fixed to the slider 310, and the other end is fixed to the end of the locking connecting rod 39.

[0056] In this embodiment, when the rotating member 35 rotates (driving the clutch rod 36 and thus moving the driven wheel II 32), the locking connecting rod 39 will also move accordingly. Since the other end of the locking connecting rod 39 is on the concave side of the arc chute and is connected to the slider 310 through the elastic member 38, the slider 310 slides in the arc chute 371. The slider 310 slides into the corresponding locking position in the arc chute 371. At this time, the elastic member 38 always provides a pulling force to lock the slider 310 in the locking position, realizing the position locking of the clutch rod 36 and the locking clutch rod 36. The self-locking stability effect is achieved.

[0057] In addition, due to the presence of the elastic member 38, when the driven wheel II 32 meshes with the driven wheel 33, the elastic member 38 can provide a certain pre-tightening force to make the cooperation between the driven wheel II 32 and the driven wheel 33 closer, avoiding disengagement due to vibration or other reasons. At the same time, during the switching process, the elastic member 38 can absorb impacts to make the switching process smooth.

[0058] In addition, in the active driving state, if the driven wheel 33 encounters excessive resistance (such as accidental impact), the elastic member 38 can deform, allowing the locking connecting rod 39 to have a small displacement, and then temporarily separating the driven wheel II 32 from the driven wheel 33, thereby avoiding hard damage to the mechanism.

[0059] Among them, the driving wheel 31 and the second transmission wheel 32 are always in a cooperative state. With this arrangement, one clutch link can be reduced, such that the second transmission wheel 32 only needs to be connected to and separated from the driven wheel 33 to achieve the clutch function. This simplifies the complexity of the clutch mechanism, especially in scenarios with limited space such as robotic legs, and can improve the structural compactness and reliability.

[0060] In one embodiment, the two ends of the arc-shaped chute 371 are respectively a connection limit position and a separation limit position; When the second transmission wheel 32 and the driven wheel 33 change from the separated state to the connected state, the slider 310 actively or passively slides from the separation limit position to the connection limit position. When the second transmission wheel 32 and the driven wheel 33 change from the connected state to the separated state, the slider 310 actively or passively slides from the connection limit position to the separation limit position.

[0061] In this embodiment, the design of the arc-shaped chute 371 can make the movement of the slider 310 natural and smooth without jamming. By configuring the two ends of the arc-shaped chute 371 as two limit positions, the arc track of the arc-shaped chute 371 can be used to form a locking point at the end of the arc-shaped chute 371, and the transition is natural through arc-shaped sliding.

[0062] In one preferred embodiment, by designing the curvature of the arc-shaped chute 371, two adjustment methods can be respectively formed: One adjustment method is that after manually adjusting the clutch lever 36, when the second transmission wheel 32 and the driven wheel 33 change from the separated state to the connected state, or when the second transmission wheel 32 and the driven wheel 33 change from the connected state to the separated state, due to the small curvature of the arc-shaped chute 371, the slider 310 will actively (automatically) slide from the separation limit position to the connection limit position, or from the connection limit position to the separation limit position. At this time, only one adjustment is required to achieve the main - passive switching.

[0063] Another adjustment method is that after manually adjusting the clutch lever 36, when the driving wheel II 32 and the driven wheel 33 are changed from the separated state to the connected state, or when the driving wheel II 32 and the driven wheel 33 are changed from the connected state to the separated state, due to the large radian of the arc-shaped chute 371, the slider 310 cannot actively (automatically) slide from the separation limit position to the connection limit position, or from the connection limit position to the separation limit position. It can only be passively slid by manual operation of the slider 310 to complete the switching. At this time, two adjustment operations are required to complete the active-passive switching. At this time, when used as a prosthetic limb, when the battery power is low, the first adjustment can be made first (at this time, the clutch lever 36 needs to be kept in a specific state continuously), which can be used for the user to adapt. If the adaptation is good, the user can make the second adjustment (adjust the slider 310) to complete the final switching. If the user's state is not good and cannot adapt, the clutch lever 36 can be released to keep the knee joint in its original state, and the remaining battery power can be used to keep oneself in a safe state and wait for rescue.

[0064] In one embodiment, the elastic member 38 is a spring. The spring has a simple and reliable structure, is convenient for disassembly and assembly, and is convenient for adjusting the elastic force, thereby controlling the adjustment sensitivity. In one embodiment, the locking portion further includes a rotating rod 311; One end of the rotating rod 311 is rotatably arranged on the chute plate 37, and the rotation axis is located at the center of the arc-shaped chute 371, and the other end is fixedly connected to the slider 310. In this embodiment, by adding the rotating rod 311, the sliding stability of the slider 310 can be improved, and the overall structural reliability can be improved.

[0065] In one embodiment, the active-passive switching structure 3 further includes a manual operating rod 312 fixed on the rotating member 35, and the manual operating rod 312 is used for manually operating the rotating member 35 to rotate. In this embodiment, the active-passive switching structure 3 is manually switched, which is applicable to the situation where the user actively controls according to the battery power when the mechanical leg is used as a prosthetic limb or an exoskeleton, and can reduce the number of electric controls.

[0066] The present invention also provides an active-passive switching method, which uses the above-mentioned active-passive switching structure 3 to perform the switching between active movement and passive movement, and includes the following steps: During active movement, by controlling the clutch lever 36, since the clutch lever 36, the rotating member 35, the locking connecting rod 39, and the manual operating lever 312 are an integral part, it is possible to operate any of the components. When the manual operating lever 312 is provided, the clutch lever 36 can be controlled through the manual operating lever 312. The driving wheel 31, the transmission wheel II 32, and the driven wheel 33 are sequentially engaged, and the locking portion maintains the engaged state of the driving wheel 31, the transmission wheel II 32, and the driven wheel 33. At this time, the rotary drive mechanism 4 drives the driving wheel 31 to rotate, the driving wheel 31 drives the driven wheel 33 to rotate, and the driven wheel 33 drives the driving part (slave / driving wheel 25) of the knee joint structure; During passive movement, by controlling the clutch lever 36, the transmission wheel II 32 and the driven wheel 33 are separated, and the locking portion maintains the separated state of the transmission wheel II 32 and the driven wheel 33. At this time, the driving part (slave / driving wheel 25) of the knee joint structure is disconnected from the rotary drive mechanism 4, and the driving part (slave / driving wheel 25) of the knee joint structure is a free end and is not connected to a load, enabling passive free movement of the knee joint structure.

[0067] The present invention also provides a knee joint system, including a knee joint structure and the above-mentioned active / passive switching structure 3; The knee joint structure includes a four-bar linkage mechanism 1 and a rotating wheel mechanism 2; The four-bar linkage mechanism 1 includes a link I 11, a link II 12, a link III 13, and a link IV 14 that are sequentially hinged end to end, where the link I 11 is used to connect the thigh of the mechanical leg, and the link III 13 is used to connect the calf of the mechanical leg; The rotating wheel mechanism 2 includes a link V 21 and a link VI 22 that are hinged to each other. A transmission wheel I 23 is rotatably provided on the hinge axis of the link V 21 and the link VI 22. A master / slave wheel 24 that rotates in cooperation with the transmission wheel I 23 is rotatably provided on the link V 21. The master / slave wheel 24 is rotatably provided on the link I 11. A slave / master wheel 25 that rotates in cooperation with the transmission wheel I 23 is rotatably provided on the link VI 22. The slave / master wheel 25 is rotatably provided on the link III 13.

[0068] The axle of the driven wheel 33 of the active / passive switching structure 3 is rotatably connected to the axle of the master / slave wheel 24 or the slave / master wheel 25.

[0069] For the working principles and effects of the four-bar linkage mechanism 1 and the rotating wheel mechanism 2 provided in this embodiment, refer to the above description.

[0070] The present invention combines the active-passive switching structure 3 with the rotating wheel mechanism 2, enabling the switching between the active movement and the passive movement of the knee joint structure. This allows the corresponding mechanical leg to still be used as a passive mechanical leg (such as a prosthetic leg) after the battery runs out. Different from conventional active-passive mechanical legs, the four-bar linkage mechanism 1, the rotating wheel mechanism 2, and the active-passive switching structure 3 provided by the present invention can achieve a small size, a compact structure, and high stability, meeting the installation requirements in a space-constrained knee joint installation position.

[0071] In one embodiment, the knee joint system further includes a rotary drive mechanism 4; The rotary drive mechanism 4 includes a motor 41, a gear set 42, and a bevel gear set 43; The driving gear of the gear set 42 is fixedly fitted with the rotating shaft of the motor 41, the driven gear is fixedly connected to the driving bevel gear of the bevel gear set 43, and the driven bevel gear of the bevel gear set 43 is fixedly connected to the axle of the driving wheel 31. This rotary drive mechanism 4 enables the motor 41 to be longitudinally arranged, and then the motor 41 can be placed in the upper part of the calf or the lower part of the thigh, thus ensuring the knee joint position.

[0072] The present invention also provides a mechanical leg, which includes the above knee joint system.

[0073] As described above, this is only an embodiment and does not impose any limitations on the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make many possible changes, modifications, or equivalent changes and modifications to the technical solution of the present invention using the above-disclosed technical content. Therefore, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the scope of protection of the technical solution of the present invention.

Claims

1. A knee joint structure, characterized in that, It includes a four-bar linkage mechanism (1) and a rotating wheel mechanism (2); The four-bar linkage mechanism (1) includes link I (11), link II (12), link III (13) and link IV (14) which are sequentially hinged end to end. Among them, link I (11) is used to connect the thigh of the mechanical leg, and link III (13) is used to connect the calf of the mechanical leg; The rotating wheel mechanism (2) includes link V (21) and link VI (22) which are hinged to each other. A driving wheel I (23) is rotatably arranged on the hinge axis of link V (21) and link VI (22). A master / slave wheel (24) which is rotationally matched with the driving wheel I (23) is rotatably arranged on link V (21). The master / slave wheel (24) is rotatably arranged on link I (11). A slave / master wheel (25) which is rotationally matched with the driving wheel I (23) is rotatably arranged on link VI (22). The slave / master wheel (25) is rotatably arranged on link III (13).

2. The knee joint structure according to claim 1, characterized in that, A connecting rod is arranged on link III (13). The connecting rod includes connecting rod I (15), connecting rod II (16) and connecting rod III (17) which are sequentially connected; Connecting rod I (15) and connecting rod III (17) are parallel to each other, and one end of connecting rod I (15) is fixed on link III (13); The slave / master wheel (25) is rotatably arranged at the end of connecting rod III (17).

3. The knee joint structure according to claim 2, characterized in that, The projection of the axis of the slave / master wheel (25) on the plane of the four-bar linkage mechanism (1) is located on link III (13).

4. The knee joint structure according to claim 3, characterized in that, Connecting rod I (15) is coplanar with the plane of the four-bar linkage mechanism (1), and the slave / master wheel (25) is located between connecting rod I (15) and connecting rod II (16).

5. The knee joint structure according to any one of claims 1-4, characterized in that, The driving wheel I (23), the master / slave wheel (24) and the slave / master wheel (25) are located between the four-bar linkage mechanism (1) and link V (21), link VI (22).

6. The knee joint structure according to any one of claims 1 to 4, characterized in that, The rotation axis of the master / slave wheel (24) is coaxial with the hinge axis of link I (11) and link II (12).

7. The knee joint structure according to any one of claims 1-4, characterized in that, The length of link I (11) is 27mm, the length of link II (12) is 80mm, the length of link III (13) is 45mm, and the length of link IV (14) is 45mm.

8. The knee joint structure according to any one of claims 1 to 3, characterized in that, The transmission ratio of the master / slave wheel (24) and the slave / master wheel (25) is 1.

9. A method for knee joint movement, characterized in that, Using the knee joint structure according to any one of claims 1-8, it includes active knee joint movement and passive knee joint movement; The active knee joint movement includes the following steps: Power output drives the master / slave wheel (24) or the slave / master wheel (25) to rotate. The master / slave wheel (24) or the slave / master wheel (25) drives the slave / master wheel (25) or the master / slave wheel (24) to rotate through the driving wheel I (23); Meanwhile, the four-bar linkage mechanism (1) and the rotating wheel mechanism (2) move in coordination to make the four-bar linkage mechanism (1) move along a specific trajectory; The passive knee joint movement includes the following steps: The connecting rod I (11) or the connecting rod III (13) moves passively, and during the passive movement, it cooperates with the rotating wheel mechanism (2) to make the four-bar linkage mechanism (1) perform a movement along a specific trajectory.

10. A mechanical leg, characterized in that, The mechanical leg includes the knee joint structure according to any one of claims 1-9.

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