Adaptive variable center of instantaneous artificial knee joint

Abstract

The application provides an adaptive variable instantaneous center artificial knee joint, which comprises a pneumatic muscle driving assembly (10) and a knee joint assembly (20). The knee joint assembly (20) comprises a thigh (21), a shank (22), a first connecting rod mechanism (23), an adjusting rod (24), a second connecting rod mechanism (25) and a rotating rod (26). The two sides of the thigh (21) and the shank (22) are connected through the rotating rod (26), the first connecting rod mechanism (23) is arranged between the thighs (21), the second connecting rod mechanism (25) is arranged between the shanks (22), and the first connecting rod mechanism (23) and the second connecting rod mechanism (25) are connected through a central shaft (200). The artificial knee joint can solve the problem of poor coordination between the existing artificial knee joint and the human leg. Meanwhile, the artificial knee joint can meet the needs of most users and adapt to the instantaneous center rotation track of different human knee joints, and has a wide application range.

Description

Technical Field

[0001] This invention relates to the field of robotics, specifically to an adaptive variable instantaneous center artificial knee joint. Background Technology

[0002] With the increasing aging of the population and the growing number of disabled people, there is an urgent need for a lower limb rehabilitation robot that can meet the human body's movement parameters, so as to assist the elderly or disabled people in postoperative rehabilitation and exercise.

[0003] Traditional prosthetic legs and lower limb exoskeletons simply treat the movement of the human knee joint as a single-hinge motion, driving the joint movement through motors or other drive devices. However, the movement of the human knee joint is a more complex spatial motion, with its instantaneous center of rotation (ICR) changing with the joint's rotation angle, tracing a J-shaped curve. Due to this variable instantaneous center of rotation trajectory, prosthetics with a fixed center of rotation inevitably result in poor coordination with the human leg, hindering patient rehabilitation and normal walking, slowing down the patient's recovery and training process, or causing walking difficulties.

[0004] Meanwhile, existing technologies also include a type of artificial knee joint with variable instantaneous center of rotation. For example, Chinese patent document CN110302036A discloses a bionic mechanism for knee joint motion with variable instantaneous center of rotation. It utilizes gear meshing between the thigh connector and the lower leg connector to simulate the surface contact rotation and translation of the upper and lower joint surfaces in the knee joint, ensuring that the rotation axis of the gear always aligns with the rotation axis of the knee joint in human anatomy. It uses a motion buffering and limiting component to simulate the patellar ligament's limiting effect on the femur and tibia and the buffering effect on knee joint rotation, allowing it to conform well to the human knee joint during flexion and extension movements. It uses a joint connecting support component as a rigid body to relieve the knee joint from load during the entire knee flexion and extension process, achieving a stress shielding effect. However, as mentioned above, the rotation trajectory of the instantaneous center of rotation (ICR) is similar to a J-shaped curve rather than a pure circular arc. Therefore, the knee joint structure in this paper cannot truly simulate the instantaneous center of rotation trajectory of the human knee joint. In addition, the instantaneous center of rotation trajectory curves of different human knee joints vary. The knee joint mechanism in this paper has poor adaptability. Once the mechanism size is determined, its instantaneous center of rotation trajectory cannot be changed, and it cannot meet the needs of different human knee joints. Summary of the Invention

[0005] To address the problems existing in the prior art, the present invention aims to provide an adaptive variable instantaneous center of rotation artificial knee joint. This artificial knee joint can solve the problem of poor coordination between existing artificial knee joints and the human leg. At the same time, this artificial knee joint can meet the needs of most users and adapt to the instantaneous center of rotation trajectory of different human knee joints, thus having a wide range of applications.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] An adaptive variable instantaneous center artificial knee joint, characterized in that it includes a pneumatic muscle drive assembly and a knee joint assembly; the knee joint assembly includes a thigh, a lower leg, a first linkage mechanism, an adjusting rod, a second linkage mechanism, and a rotating rod, the thigh and lower leg are respectively connected by rotating rods (i.e., there are two rotating rods, and the two ends of the same rotating rod are respectively rotatably connected to the thigh and the lower leg), the first linkage mechanism is located between the thighs and the second linkage mechanism is located between the lower legs, and the first linkage mechanism and the second linkage mechanism are connected by a central shaft, the adjusting rod is provided with a first sliding groove and the lower leg is provided with a second sliding groove, the central shaft is sequentially engaged in the first sliding groove and the second sliding groove and slidably connected, the end of the adjusting rod away from the sliding groove is coaxially arranged with the first connecting mechanism, and the end of the rotating rod located in the lower leg is coaxially arranged with the second connecting mechanism.

[0008] For further optimization, the centerline of the first slide groove and the centerline of the second slide groove are at a certain angle and the angle is not less than 30°.

[0009] For further optimization, a first hollow groove is provided in the middle of the thigh, the lower leg is provided in the first hollow groove, a second hollow groove is provided in the middle of the lower leg, and the first linkage mechanism, adjusting rod, and second linkage mechanism are provided in the second hollow groove; rotating grooves are provided on both sides of the thigh, and rotating rods are provided in the rotating grooves.

[0010] For further optimization, the first linkage mechanism includes a first drive shaft, two first connecting rods, two second connecting rods, and a first driven shaft. The first drive shaft passes through both sides of the thigh sidewall and is rotatably connected to the thigh sidewall. The first drive shaft is fixedly sleeved on the outer wall between the second hollow slots, and the first connecting rods are symmetrically arranged. The ends of the two first connecting rods away from the first drive shaft are connected through the same first driven shaft. The first driven shaft is sleeved on the outer wall of the side of the two first connecting rods away from each other, and the ends of the second connecting rods away from the first driven shaft are sleeved on the outer wall of the central shaft. The second linkage mechanism includes a second drive shaft, two third connecting rods, two fourth connecting rods, and... A second driven shaft and a second drive shaft pass through the side walls of both sides of the lower leg and are rotatably connected to the side walls of the lower leg. Two third connecting rods are fixedly sleeved on the outer wall of the second drive shaft between the second hollow slots. The ends of the two third connecting rods away from the second drive shaft are connected through the same second driven shaft. A fourth connecting rod is sleeved on the outer wall of the side of the two third connecting rods that are close to each other. The end of the fourth connecting rod away from the second driven shaft is sleeved on the outer wall of the central shaft. There are two adjusting rods. One end of the adjusting rod is rotatably sleeved on the outer wall of the first drive shaft, and the other end is connected through an auxiliary shaft. The end of the adjusting rod away from the first drive shaft is provided with a first sliding groove. The end of the rotating rod away from the thigh is rotatably sleeved on the outer wall of the second drive shaft.

[0011] Preferably, the second link is located between the two adjusting rods, and the fourth link is located between the two second links.

[0012] For further optimization, a first motor is provided on the thigh sidewall corresponding to the first drive shaft to drive the first drive shaft to rotate; a second motor is provided on the calf sidewall corresponding to the second drive shaft to drive the second drive shaft to rotate.

[0013] For further optimization, a first angle sensor is provided on the thigh sidewall and corresponding to the first drive shaft, a second angle sensor is provided on the thigh sidewall and corresponding to the rotating shaft at the thigh end, and a third angle sensor is provided on the calf sidewall and corresponding to the second drive shaft, respectively, for detecting the rotation angle of each rotating shaft.

[0014] For further optimization, the pneumatic muscle drive assembly consists of two sets, including a pneumatic actuator and drive ropes. One end of the pneumatic actuator is connected to the drive rope and is used to control the extension and retraction of the drive rope. The ends of the two drive ropes away from the pneumatic actuator are respectively connected to the second drive shaft and the central shaft. By controlling the extension and retraction of the two drive ropes through the pneumatic actuator, the knee joint assembly is controlled to complete the knee flexion movement (i.e., the relative rotation between the thigh and the lower leg).

[0015] The present invention has the following technical effects:

[0016] This application utilizes a pneumatic muscle drive assembly to achieve relative clockwise or counterclockwise rotation between the lower leg and thigh, thereby completing knee flexion. The rotation of the first linkage mechanism enables the central axis to slide within the first groove of the adjusting rod, and the rotation of the second linkage mechanism enables the central axis to slide within the second groove of the lower leg. This alters the relative movement length of the adjusting rod relative to the lower leg, indirectly changing the linkage length at the joint by introducing additional degrees of freedom. This allows for adjustment of the intersection point between the adjusting rod and the rotating rod, i.e., the instantaneous center of rotation (ICR), ensuring that the knee joint assembly conforms to the instantaneous center of rotation curve (J-curve) of the human knee joint during knee flexion and rotation. This ensures the knee joint assembly's adaptability to the human knee joint, improving rehabilitation, exercise, and walking assistance. Furthermore, the combination of the first linkage mechanism, the second linkage structure, and the first and second grooves allows this application to adapt to different instantaneous center of rotation curves of the human knee joint, resulting in wide applicability and high reliability. Furthermore, this application ensures that the joint has a certain rigidity by antagonizing the arrangement of the pneumatic muscle drive components and the connecting rods, and the joint rigidity can be changed according to actual needs, resulting in a structure with versatility and adaptability. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the artificial knee joint in an embodiment of the present invention.

[0018] Figure 2 This is a frontal perspective view of the knee joint assembly of the artificial knee joint in an embodiment of the present invention.

[0019] Figure 3 This is a three-dimensional rear view of the knee joint assembly of the artificial knee joint in an embodiment of the present invention.

[0020] Figure 4 This is a front plan view of the knee joint assembly of the artificial knee joint in an embodiment of the present invention.

[0021] Figure 5 This is a front structural diagram of the first linkage mechanism, adjusting rod, second linkage mechanism, and rotating rod of the artificial knee joint in an embodiment of the present invention.

[0022] Figure 6 This is a schematic diagram of the rear structure of the first linkage mechanism, adjusting rod, second linkage mechanism, and rotating rod of the artificial knee joint in an embodiment of the present invention.

[0023] Figure 7 The diagram illustrates the optimized variation patterns of the adjusting rod and the lower leg in this embodiment of the invention; where A represents the change in lower leg length and B represents the change in adjusting rod length.

[0024] Figure 8 This is a comparison chart of the instantaneous heart trajectory curve of the knee joint assembly and the ideal instantaneous heart trajectory curve of the human knee joint in an embodiment of the present invention.

[0025] Among them, 100 is the frame; 101 is the pulley block; 10 is the pneumatic muscle drive assembly; 11 is the pneumatic actuator; 12 is the drive rope; 20 is the knee joint assembly; 200 is the central shaft; 21 is the thigh; 211 is the first hollow groove; 212 is the rotating groove; 213 is the first motor; 214 is the first angle sensor; 215 is the second angle sensor; 22 is the lower leg; 221 is the second hollow groove; 222 is the second slide; 223 is the second motor; 224 is the third angle sensor; 23 is the first linkage mechanism; 231 is the first drive shaft; 232 is the first link; 233 is the second link; 234 is the first driven shaft; 24 is the adjusting rod; 241 is the first slide; 242 is the auxiliary shaft; 25 is the second linkage mechanism; 251 is the second drive shaft; 252 is the third link; 253 is the fourth link; 254 is the second driven shaft; and 26 is the rotating rod. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0027] Example 1:

[0028] like Figures 1-6 As shown, an adaptive variable instantaneous center artificial knee joint is characterized by comprising a pneumatic muscle drive assembly 10 and a knee joint assembly 20; the knee joint assembly 20 includes a thigh 21, a lower leg 22, a first linkage mechanism 23, an adjusting rod 24, a second linkage mechanism 25, and a rotating rod 26, wherein the thigh 21 and the lower leg 22 are respectively connected by the rotating rod 26 (i.e., there are two rotating rods 26, and the two ends of the same rotating rod 26 are respectively rotatably connected to the thigh 21 and the lower leg 22), a first hollow groove 211 is provided in the middle of the thigh 21, and the lower leg 22 is disposed in the first hollow groove 211 (e.g., Figure 2 , Figure 4 As shown), a second hollow groove 221 is provided in the middle of the lower leg 22. The first linkage mechanism 23, the adjusting rod 24, and the second linkage mechanism 25 are arranged in the second hollow groove 221. The first linkage mechanism 23 is arranged corresponding to the thigh 21, and the second linkage mechanism 25 is arranged corresponding to the lower leg 22. Rotating grooves 212 are provided on both sides of the thigh 21, and the rotating rod 26 (i.e. the end of the rotating rod 26 that connects to the thigh 21) is arranged in the rotating groove 212.

[0029] like Figure 5 , Figure 6 As shown: The first linkage mechanism 23 includes a first drive shaft 231, two first connecting rods 232, two second connecting rods 233, and a first driven shaft 234. The first drive shaft 231 passes through both side walls of the thigh 21 and is rotatably connected to the side walls of the thigh 21 (e.g., Figures 2-3As shown: The first drive shaft 231 passes through the side walls of the thigh 21 and the rotating groove 213 at both ends. The first drive shaft 231 is located on the outer wall between the second hollow groove 221 and is fixedly sleeved with two first connecting rods 232, which are symmetrically arranged. The ends of the two first connecting rods 232 away from the first drive shaft 231 are connected by the same first driven shaft 234. The first driven shaft 234 is located on the outer wall of the side of the two first connecting rods 232 away from each other and is sleeved with second connecting rods 233. The ends of the second connecting rods 233 away from the first driven shaft 234 are sleeved on the outer wall of the central shaft 200. The second linkage mechanism 25 includes a second drive shaft 251, two third connecting rods 252, two fourth connecting rods 253 and a second driven shaft 254. The two ends of the second drive shaft 251 pass through the side walls of the lower leg 22 and are rotatably connected to the side walls of the lower leg 22. Two third connecting rods 252 are fixedly sleeved on the outer wall of shaft 251 between the second hollow grooves 221. The ends of the two third connecting rods 252 away from the second drive shaft 251 are connected by the same second driven shaft 254. The outer wall of the second driven shaft 254 on the side of the two third connecting rods 252 that are close to each other is respectively sleeved with a fourth connecting rod 253. The end of the fourth connecting rod 253 away from the second driven shaft 254 is sleeved on the outer wall of the central shaft 200. There are two adjusting rods 24. One end of the adjusting rod 24 is rotatably sleeved on the outer wall of the first drive shaft 231, and the other end is connected by an auxiliary shaft 242. The end of the adjusting rod 24 away from the first drive shaft 231 is provided with a first sliding groove 241. The end of the rotating rod 26 away from the thigh 21 is rotatably sleeved on the outer wall of the second drive shaft 251. The second connecting rod 233 is located between the two adjusting rods 24, and the fourth connecting rod 253 is located between the two second connecting rods 233. The lower leg 22 is provided with a second sliding groove 222, and the central shaft 200 (i.e., the central shaft 200 is located at both ends of the second connecting rod 233) is sequentially engaged in the first sliding groove 241 and the second sliding groove 222 and slidably connected; the centerline of the first sliding groove 241 and the centerline of the second sliding groove 222 form a certain angle and the angle is not less than 30° (e.g., Figure 3 As shown, in this embodiment, the angle between the center lines of the first slide groove 241 and the second slide groove 222 is 90° to 120°.

[0030] A first motor 213 is provided on the side wall of the thigh 21 corresponding to the first drive shaft 231 to drive the first drive shaft 231 to rotate; a second motor 223 is provided on the side wall of the calf 22 corresponding to the second drive shaft 251 to drive the second drive shaft 251 to rotate; a first angle sensor 214 is provided on the side wall of the thigh 21 corresponding to the first drive shaft 231; a second angle sensor 215 is provided on the side wall of the thigh 21 corresponding to the rotating shaft 26 located at the end of the thigh 21; and a third angle sensor 224 is provided on the side wall of the calf 22 corresponding to the second drive shaft 251, respectively, to detect the rotation angle of each rotating shaft.

[0031] The pneumatic muscle drive assembly 10 consists of two sets, including a pneumatic actuator 11 and a drive rope 12, such as... Figure 1 As shown: the pneumatic actuator 11 and the end of the thigh 21 away from the lower leg 22 are both fixedly mounted on the frame 100; and a pulley assembly 101 is provided on the frame 100 corresponding to the pneumatic actuator 11. The pneumatic actuator 11 is connected to one end of the drive rope 12 and is used to control the extension and retraction of the drive rope 12; the ends of the two drive ropes 12 away from the pneumatic actuator 11 are connected to the second drive shaft 251 and the central shaft 200 (or auxiliary shaft 242) respectively after passing through the corresponding pulley assembly 101. By controlling the extension and retraction of the two drive ropes 12 through the pneumatic actuator 11, the knee joint assembly 20 is controlled to complete the knee flexion movement (i.e., the relative rotation between the thigh 21 and the lower leg 22).

[0032] Working principle:

[0033] When using, through Figure 1 The pneumatic actuator 11 on the left controls the extension of its corresponding drive rope 12, while simultaneously... Figure 1 The pneumatic actuator 11 on the right controls the retraction of its corresponding drive rope 12, thereby causing the lower leg 22 to rotate counterclockwise relative to the thigh 21; conversely, when... Figure 1 The pneumatic actuator 11 on the left controls the retraction of its corresponding drive rope 12, while simultaneously... Figure 1 The pneumatic actuator 11 on the right controls the extension of its corresponding drive rope 12, which causes the lower leg 22 to rotate clockwise relative to the thigh, thereby completing the knee flexion movement from 0 to 120°.

[0034] By activating the first motor 213 to control the rotation of the first drive shaft 231, the central shaft 200 slides within the first groove 241 of the adjusting rod 24 through the cooperation of the first connecting rod 232, the first driven shaft 234, and the second connecting rod 233, thus changing the actual length of the adjusting rod 24. By activating the second motor 223 to control the rotation of the second drive shaft 251, the central shaft 200 slides within the second groove 222 through the cooperation of the third connecting rod 252, the second driven shaft 254, and the fourth connecting rod 253, thus adjusting the length of the lower leg 22. By adjusting the actual length of the adjusting rod 24 and the length of the lower leg 22, the intersection point between the adjusting rod 24 and the rotating rod 26 is changed, thereby adjusting the instantaneous center of gravity of the joint.

[0035] Example 2:

[0036] As a further optimization of the solution in this application, based on Embodiment 1, this application also provides a method for obtaining an adaptive variable instantaneous center of gravity knee joint trajectory, using the aforementioned artificial knee joint, and the specific steps are as follows:

[0037] Step 1: First, establish the kinematic system of the artificial knee joint;

[0038] Step 2: Establish the ideal instantaneous center of gravity trajectory equation for the human knee joint based on motion constraints;

[0039] Step 3: Select data from the artificial knee joint components in Example 1, such as the dimensions of the thigh 21, lower leg 22, adjusting rod 24, rotating rod 26, and the initial joint movement position, as optimization parameters;

[0040] Step 4: Establish the objective function of the particle swarm optimization algorithm based on the ideal instantaneous center of gravity trajectory equation of the human knee joint, and perform particle swarm optimization; the optimized result is the initial structural dimensions of the artificial knee joint.

[0041] Step 5: Keeping the thigh 21, rotating rod 26, and initial joint position unchanged, and using adjusting rod 24 and lower leg 22 as optimization parameters, construct a new objective function again, and then perform a second particle swarm optimization. This will yield the actual changes in adjusting rod 24 and lower leg 22 during the artificial knee joint flexion process from 0 to 120°, such as... Figure 7 As shown.

[0042] Finally, the comparison results between the instantaneous center of gravity trajectory of the adaptive variable instantaneous center of gravity artificial knee joint in this embodiment and the ideal instantaneous center of gravity trajectory of the human body are as follows: Figure 8 As shown; by Figure 8 It is understood that the instantaneous cardiac trajectory of this artificial knee joint during knee flexion has a good match with the ideal instantaneous cardiac trajectory of the human body; at the same time, the adjustability of the adjustment rod 24 and the lower leg 22 can be adjusted when the actual instantaneous cardiac trajectory of different users' legs is different, so that it can meet the needs of the vast majority of users as much as possible.

[0043] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims. Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This method of description is merely for clarity, and those skilled in the art should consider the specification as a whole. The technical solutions in the various embodiments can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An adaptive variable instantaneous center of gravity artificial knee joint, characterized in that: The invention includes a pneumatic muscle drive assembly and a knee joint assembly. The knee joint assembly includes a thigh, a lower leg, a first linkage mechanism, an adjusting rod, a second linkage mechanism, and a rotating rod. The thigh and lower leg are connected on both sides by rotating rods. The first linkage mechanism is located between the thigh and the second linkage mechanism is located between the lower leg. The first linkage mechanism and the second linkage mechanism are connected by a central shaft. The adjusting rod is provided with a first sliding groove and the lower leg is provided with a second sliding groove. The central shaft is sequentially engaged in the first sliding groove and the second sliding groove and is slidably connected. The end of the adjusting rod away from the sliding groove is coaxially arranged with the first connecting mechanism, and the end of the rotating rod located in the lower leg is coaxially arranged with the second connecting mechanism. A first hollow groove is provided in the middle of the thigh, the lower leg is provided in the first hollow groove, a second hollow groove is provided in the middle of the lower leg, and a first linkage mechanism, an adjusting rod, and a second linkage mechanism are provided in the second hollow groove; rotating grooves are provided on both sides of the thigh, and rotating rods are provided in the rotating grooves. The first linkage mechanism includes a first drive shaft, two first connecting rods, two second connecting rods, and a first driven shaft. The first drive shaft passes through both sides of the thigh and is rotatably connected to the thigh sidewalls. The first drive shaft is fixedly sleeved on the outer wall between the second hollow slots, and the first connecting rods are symmetrically arranged. The ends of the two first connecting rods away from the first drive shaft are connected through the same first driven shaft. The first driven shaft is sleeved on the outer wall of the two first connecting rods on opposite sides, and the ends of the second connecting rods away from the first driven shaft are sleeved on the outer wall of the central shaft. The second linkage mechanism includes a second drive shaft, two third connecting rods, two fourth connecting rods, and a first driven shaft. Two driven shafts are connected to the second drive shaft, which passes through both sides of the lower leg and is rotatably connected to the lower leg side walls. Two third connecting rods are fixedly sleeved on the outer wall of the second drive shaft between the second hollow slots. The ends of the two third connecting rods away from the second drive shaft are connected through the same second driven shaft. The second driven shaft is sleeved on the outer wall of the side of the two third connecting rods that are close to each other. The end of the fourth connecting rod away from the second driven shaft is sleeved on the outer wall of the central shaft. There are two adjusting rods. One end of the adjusting rod is rotatably sleeved on the outer wall of the first drive shaft, and the other end is connected through an auxiliary shaft. The end of the adjusting rod away from the first drive shaft is provided with a first sliding groove. The end of the rotating rod away from the thigh is rotatably sleeved on the outer wall of the second drive shaft.

2. The adaptive variable instantaneous center of gravity artificial knee joint according to claim 1, characterized in that: The second link is located between the two adjusting rods, and the fourth link is located between the two second links.

3. An adaptive variable instantaneous center artificial knee joint according to claim 1 or 2, characterized in that: The thigh sidewall is provided with a first motor corresponding to the first drive shaft; the calf sidewall is provided with a second motor corresponding to the second drive shaft.

4. The adaptive variable instantaneous center of gravity artificial knee joint according to claim 3, characterized in that: A first angle sensor is provided on the thigh sidewall and corresponding to the first drive shaft; a second angle sensor is provided on the thigh sidewall and corresponding to the rotating shaft at the thigh end; and a third angle sensor is provided on the calf sidewall and corresponding to the second drive shaft.

5. An adaptive variable instantaneous center artificial knee joint according to claim 1 or 2, characterized in that: The pneumatic muscle drive assembly consists of two sets, including a pneumatic actuator and a drive rope, with one end of the pneumatic actuator connected to the drive rope; the ends of the two drive ropes furthest from the pneumatic actuator are respectively connected to the second drive shaft and the central shaft.

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