Ankle rehabilitation robot coupled with joint axis

Abstract

The application discloses a joint axis coupled ankle rehabilitation robot, which comprises a base, a support fixedly connected to the base, a first frame, a second frame, a third frame, a foot fixing device and a first closed motion chain and a second closed motion chain.

Description

Technical Field

[0001] This invention belongs to the field of joint medical rehabilitation equipment technology, specifically relating to an ankle joint rehabilitation robot with joint axis coupling. Background Technology

[0002] The ankle joint, as one of the most important weight-bearing and movement joints in the lower limbs, bears the key functions of walking, running, jumping, and turning. Functional impairment of the ankle is commonly seen after fracture surgery, stroke hemiplegia, spinal cord injury, and sports sprains. In clinical rehabilitation, passive, assisted, and resistance training are the core methods for restoring ankle dorsiflexion, plantar flexion, inversion, eversion, and compound movement functions. The application of ankle rehabilitation robots provides a feasible technical path for achieving efficient, precise, and low-cost rehabilitation training.

[0003] The ankle joint is composed of the tibia, fibula, talus, calcaneus, and related soft tissues. The tibia, fibula, and talus form the tibiotalar joint (primarily enabling dorsiflexion / plantarflexion), while the talus and calcaneus form the subtalar joint (primarily enabling inversion / eversion). Under normal physiological conditions, the ankle joint exhibits natural inversion / eversion coupling movements during dorsiflexion / plantarflexion. Its axis of motion is not a fixed single axis but rather an instantaneous spiral axis that changes with the joint angle.

[0004] Currently, existing ankle rehabilitation equipment is mainly divided into two categories: single-degree-of-freedom (DOF) and multi-degree-of-freedom (MDF). Single-degree-of-freedom devices (such as rocker-type and crank-rocker-type devices) have simple structures, but can only achieve reciprocating motion in a single plane, failing to simulate the inherent coupling motion between ankle dorsiflexion / plantar flexion and inversion / eversion. This results in the rehabilitation trajectory deviating from the physiological path, leading to low rehabilitation efficiency. Multi-degree-of-freedom devices (such as parallel mechanisms and serial joint robots) can achieve multi-directional movement, but generally suffer from the following shortcomings:

[0005] Mismatch of motion axis: The rotation axis of most devices deviates from the actual changes of the human ankle joint. Some existing devices also treat the ankle joint as an equivalent spherical joint, but this does not match the actual physiological joint movement. It can easily cause abnormal stress on the joint surface, cartilage wear and abnormal ligament traction, and long-term use may cause secondary damage.

[0006] Redundant structure and large size: Some multi-degree-of-freedom devices use redundant drives or exoskeleton-style long linkage structures, resulting in large size and heavy weight, which is not convenient for moving and storing at the bedside or home rehabilitation scene.

[0007] Complex to wear and poor adaptability: Existing devices mostly use rigid straps or fixed-size foot braces, which are difficult to adapt to different foot sizes and joint range of motion. The wearing process is cumbersome and prone to relative slippage, affecting the accuracy of rehabilitation trajectory transmission.

[0008] Therefore, how to provide a novel ankle rehabilitation device that adapts its motion axis to the physiological movement of the ankle joint, has a compact structure, is easy to wear, and can simulate coupled movements is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0009] In view of this, the present invention provides an ankle joint rehabilitation robot with joint axis coupling. Through a multi-axis coupling structure and modular drive chain, it can achieve precise rehabilitation training that is consistent with the physiological movement of the human ankle joint, thereby improving the rehabilitation effect and the safety of use.

[0010] To achieve the above objectives, the present invention adopts the following technical solution: an ankle joint rehabilitation robot with joint axis coupling, comprising: The base is fixedly connected to a support; A first frame, one end of which is rotatably connected to the support and forms a first pivot. A second frame is rotatably connected to the other end of the first frame and forms a second pivot. The first pivot and the second pivot are coupled to the physiological motion axis of the subtalar joint. The third frame is rotatably connected to the end of the second frame away from the second pivot and forms the third pivot. A foot fixation device is used to fix the patient's foot. The foot fixation device is rotatably connected to the other end of the third frame and forms a fourth pivot. The third pivot and the fourth pivot are coupled with the physiological motion axis of the tibiotalar joint. The second frame is connected to the base via two drive chains to form a first closed kinematic chain, and the foot stabilizer is connected to the base via two drive chains to form a second closed kinematic chain. Under the action of the first and second closed kinematic chains, the foot stabilizer can drive the foot to achieve dorsiflexion, plantarflexion, inversion, eversion and compound movements of the ankle joint.

[0011] The beneficial technical effects of this invention are as follows: By dividing the four drive chains into two groups and coupling the physiological motion axis of the subtalar joint and the physiological motion axis of the tibiotalar joint respectively, and by coupling the first and second rotating shafts to the subtalar joint axis and the third and fourth rotating shafts to the tibiotalar joint axis, the motion axis of the mechanism is no longer fixed orthogonal, but can dynamically approximate the physiological spiral axis of the human ankle joint. The "double closed kinematic chain hybrid configuration" is used to achieve drive and constraint, so that the movement of the foot fixation device is constrained by the two closed chains. Even if the drive chains perform simple extension and contraction, the motion coupling between dorsiflexion / plantar flexion and inversion / eversion can be naturally generated. This provides a truly biomechanically sound and cost-effective device for ankle rehabilitation, with significant clinical practical value and industrialization prospects.

[0012] Preferably, it also includes a calf support, which is obliquely and fixedly connected to the base and close to the heel side of the foot stabilizer, and the calf support is detachably connected to an elastic leg strap.

[0013] The resulting technical effects are: stable constraint and comfortable fixation of the lower leg, ensuring that the relative positional relationship between the tibia and talus during ankle joint movement is highly consistent with the axis of motion of the mechanism, eliminating the interference of compensatory movement of the lower leg on the rehabilitation trajectory, improving the accuracy of axial coupling and the effectiveness of rehabilitation training; at the same time, the slider setting simplifies the clinical operation process.

[0014] Preferably, the drive chain includes a connecting seat, a universal joint, and a telescopic push rod. The connecting seat is fixedly connected to the base. There are two sets of universal joints, which are respectively fixedly connected to both ends of the telescopic push rod. The universal joint near the fixed end of the telescopic push rod is rotatably connected to the connecting seat, and the universal joint near the telescopic end of the telescopic push rod is fixedly connected to the foot holder or the second frame. Based on the linear extension and retraction of the two drive chains, the spatial position of the first closed kinematic chain or the second closed kinematic chain can be changed.

[0015] The resulting technical effects are: strong motion decoupling, improved axial coupling accuracy, and the design of double universal joints at the proximal and distal ends, which allows both ends of the push rod to adaptively adjust their posture during extension and retraction, avoiding additional bending moments on the push rod and ensuring efficient transmission of driving force along the push rod axis. In a closed kinematic chain, the double universal joint structure effectively eliminates motion interference caused by manufacturing errors or assembly deviations, making the actual motion trajectory of the foot stabilizer closer to the preset ankle joint coupling axis. It also has the advantages of simple structure and easy assembly.

[0016] Preferably, the linear extension and retraction of the drive branch corresponding to the first closed kinematic chain can act on the second frame relative to the base in a combined motion around the first and second rotating axes. Based on the motion of the second frame, the linear extension and retraction of the drive branch corresponding to the second closed kinematic chain can act on the foot retainer relative to the second frame in a combined motion around the third and fourth rotating axes.

[0017] The resulting technical effect is that the complex movement of the ankle joint is decomposed into two independent movement levels: the subtalar joint level (first and second rotation axes) and the tibiotalar joint level (third and fourth rotation axes). Each level is independently controlled by two sets of drive branches. The graded drive reduces the complexity of control and improves the accuracy of trajectory tracking. Depending on the patient's injury type (such as subtalar joint stiffness or post-tibial-talar joint fracture surgery), one level can be selectively strengthened for training, while the other level remains in motion or slightly assisted, achieving targeted rehabilitation and avoiding compensation caused by overall linkage.

[0018] Preferably, the first rotating shaft intersects the second rotating shaft perpendicularly, and the third rotating shaft intersects the fourth rotating shaft perpendicularly. The first rotating shaft, the second rotating shaft, the third rotating shaft, and the fourth rotating shaft work together to form a coupled motion axis consistent with the human ankle joint.

[0019] The resulting technical effect is that by setting the first and second rotating axes to intersect perpendicularly, and the third and fourth rotating axes to intersect perpendicularly, and with the synergy of the hybrid configuration and the layered drive chain, the overall output of the four rotating axes is made to be consistent with the dynamic coupling motion axis of the human ankle joint, thus achieving a unity of geometric simplicity and physiological motion complexity.

[0020] Preferably, the foot restraint includes a foot pedal, an elastic foot strap, a universal joint fixing seat, and connecting lugs. The elastic foot strap is detachably connected to the middle of both sides of the foot pedal. The universal joint fixing seat is fixedly disposed on the middle of the bottom side of the foot pedal. There are two sets of connecting lugs, which are respectively fixed to the two ends of the foot pedal near the heel. The foot restraint is rotatably connected to the third frame through the two sets of connecting lugs.

[0021] The resulting technical effect is that the modular construction makes it easy for patients to wear, while the force of the drive chain can be stably transmitted to the foot pedal, thereby achieving stable simulation of joint movements.

[0022] Preferably, a drive branch connector is fixedly provided at one end of the second frame away from the second rotating shaft. The drive branch connector is used to fix one end of the two drive branches corresponding to the first closed motion chain, and the other end of the two drive branches corresponding to the first closed motion chain is fixedly connected to the base.

[0023] The resulting technical effect is that the two branches act on the free end (i.e., the second frame), which makes the second frame's attitude adjustment stable. The two branches are naturally distributed in a V-shape, resulting in high space utilization and no risk of collision.

[0024] Preferably, the two drive chains corresponding to the first closed kinematic chain are located on both sides of the support.

[0025] The resulting technical effects are: it helps to achieve force balance and smooth movement, while avoiding motion interference and expanding the workspace.

[0026] Preferably, the first closed kinematic chain and the second closed kinematic chain are staggered on the base.

[0027] The resulting technical effect is that, in practice, the first closed kinematic chain and the second closed kinematic chain are misaligned front to back and inside to outside on the base, avoiding the opening of space and ensuring the stability of the movement. Attached Figure Description

[0028] Figure 1This is a schematic diagram of the structure of an ankle joint rehabilitation robot with joint axis coupling according to the present invention. Figure 1 ; Figure 2 This is a schematic diagram of the structure of an ankle joint rehabilitation robot with joint axis coupling according to the present invention. Figure 2 ; Figure 3 This is a schematic diagram of the structure of an ankle joint rehabilitation robot with joint axis coupling according to the present invention. Figure 3 ; Figure 4 This is a schematic diagram of the drive branch structure of an ankle joint rehabilitation robot with joint axis coupling according to the present invention. Figure 5 This is a schematic diagram of the foot fixation device in the structural diagram of an ankle joint rehabilitation robot with joint axis coupling according to the present invention. Figure 6 This is a schematic diagram of the first closed kinetic chain structure of an ankle joint rehabilitation robot with joint axis coupling according to the present invention; Figure 7 This is a schematic diagram of the second closed kinetic chain structure of an ankle joint rehabilitation robot with joint axis coupling according to the present invention; Figure 8 This is a diagram of the human ankle joint.

[0029] 1. Base, 2. Support, 3. First frame, 4. Second frame, 5. Third frame, 6. Foot fastener, 61. Foot pedal, 62. Elastic foot strap, 63. Universal joint mounting base, 64. Connecting lug, 7. Drive chain, 71. Connecting seat, 72. Universal joint, 73. Telescopic push rod, 8. Lower leg bracket, 9. Elastic leg strap, 10. Drive chain connecting seat. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] See the appendix of this invention. Figures 1 to 7 and the corresponding human ankle joint Figure 8 According to an embodiment of the present invention, an ankle joint rehabilitation robot with joint axis coupling includes: Base 1, also known as the base, provides a foundation for supporting and connecting related accessories. Support 2 is fixedly connected to base 1. The first frame 3 has one end of the first frame 3 rotatably connected to the support 2 and forming the first pivot. The second frame 4 is rotatably connected to the other end of the first frame 3 and forms a second pivot. The first pivot and the second pivot are coupled to the axis of the lower lateral joint. The first pivot and the second pivot are located at both ends of the first frame. The third frame 5 is rotatably connected to the end of the second frame 4 away from the second pivot and forms the third pivot. Foot fixation device 6 is used to fix the patient's foot. Foot fixation device 6 is rotatably connected to the other end of the third frame 5 and forms a fourth pivot. The third pivot and the fourth pivot are coupled with the axis of the tibiotalar joint. The third pivot and the fourth pivot are located at both ends of the third frame. The first frame 3, the second frame 4, and the third frame 5 are all U-shaped frames. The drive chain 7 has four branches. The second frame 4 is connected to the base 1 through two drive chains 7 to form the first closed kinematic chain. The foot stabilizer 6 is connected to the base 1 through the other two drive chains 7 to form the second closed kinematic chain. Under the action of the first and second closed kinematic chains, the foot stabilizer 6 can drive the foot to achieve dorsiflexion, plantarflexion, inversion, eversion and compound movements of the ankle joint.

[0032] To improve the rehabilitation effect of the ankle joint, a calf support 8 is also included. The calf support 8 is tilted and fixedly connected to the base 1 and close to the heel side of the foot stabilizer 6. The calf support 8 is detachably connected to an elastic leg strap 9 to facilitate the fixation of the calf.

[0033] In other embodiments, the drive chain 7 includes a connecting seat 71, a universal joint 72, and a telescopic push rod 73. The connecting seat 71 is fixedly connected to the base 1. There are two sets of universal joints 72, which are respectively fixedly connected to the two ends of the telescopic push rod 73 (i.e., the drive seat and the push rod). The universal joint near the fixed end of the telescopic push rod 73 is rotatably connected to the connecting seat 71, and the universal joint near the telescopic end of the telescopic push rod 73 is fixedly connected to the foot retainer 6 or the second frame 4. Based on the linear extension and retraction of the two drive chains 7, the spatial position of the first closed kinematic chain or the second closed kinematic chain can be changed.

[0034] In practice, the telescopic push rod can be an electric push rod.

[0035] In other specific embodiments, the linear extension and retraction of the drive branch corresponding to the first closed kinematic chain can act on the second frame 4 relative to the base 1 in a compound motion around the first and second rotating axes. Based on the motion of the second frame, the linear extension and retraction of the drive branch corresponding to the second closed kinematic chain can act on the foot retainer 6 relative to the second frame 4 in a compound motion around the third and fourth rotating axes.

[0036] In other embodiments, the first axis of rotation intersects the second axis of rotation perpendicularly, and the third axis of rotation intersects the fourth axis of rotation perpendicularly. The first axis of rotation, the second axis of rotation, the third axis of rotation, and the fourth axis of rotation work together to form a coupled motion axis consistent with the human ankle joint.

[0037] In some other embodiments, the foot restraint 6 includes a foot pedal 61, an elastic foot strap 62, a universal joint fixing seat 63, and connecting lugs 64. The elastic foot strap 62 is detachably connected to the middle of both sides of the foot pedal 61. The universal joint fixing seat 63 is fixedly disposed on the middle of the bottom side of the foot pedal 61. There are two sets of connecting lugs 64, which are respectively fixed to the two ends of the foot pedal 61 near the heel. The foot restraint 6 is rotatably connected to the third frame 5 through the two sets of connecting lugs 64.

[0038] In some other specific embodiments, a drive branch connection seat 10 is fixedly provided at one end of the second frame 4 away from the second rotating shaft. The drive branch connection seat 10 is used to fix one end of the two drive branches corresponding to the first closed motion chain, and the other end of the two drive branches corresponding to the first closed motion chain is fixedly connected to the base 1.

[0039] In other embodiments, the two drive chains corresponding to the first closed kinematic chain are located on both sides of the support 2.

[0040] The first closed motion chain and the second closed motion chain are staggered on the base 1, specifically staggered front to back and inside to avoid motion interference.

[0041] Working principle: The calf support 8 of this invention fixes the patient's calf with elastic leg straps 9, and the foot pedal 61 fixes the foot with elastic foot straps 62. The first and second rotating axes are coupled to the physiological motion axis of the subtalar joint of the ankle joint, and the third and fourth rotating axes are coupled to the physiological motion axis of the tibiotalar joint of the ankle joint. The motion axis of this invention's ankle joint rehabilitation robot with joint axis coupling is coupled to the physiological ankle joint axis of the human body. The telescopic push rods 73 of the four drive chains 7 extend and retract, driving the ankle joint to perform dorsiflexion, plantarflexion, inversion, eversion, and compound movements, achieving precise rehabilitation training consistent with the physiological movements of the human ankle joint.

[0042] In practice, the calf support is fixed to the patient's calf with an elastic leg strap, and the foot pedal is fixed to the foot with an elastic foot strap. The structure is simple and the fixation is reliable.

[0043] The axes of the first, second, third, and fourth rotating axes of this invention form the basis for coupling the motion axis of the ankle joint rehabilitation robot with the physiological ankle joint axis of the human body, enabling precise rehabilitation training that is consistent with the physiological movement of the human ankle joint.

[0044] This invention utilizes the driving branch as a constraint branch simultaneously. Two different constraint branches act at different levels, coordinating their movement to decouple the complex motion trajectory of the ankle joint. This results in high motion precision and high driving efficiency.

[0045] The apparatus and methods disclosed in the embodiments are described simply because they correspond to the methods disclosed in the embodiments. For relevant details, please refer to the method section.

[0046] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An ankle joint rehabilitation robot with joint axis coupling, characterized in that, include: Base (1), the base (1) is fixedly connected to a support (2); The first frame (3) is rotatably connected to the support (2) at one end and forms the first pivot. The second frame (4) is rotatably connected to the other end of the first frame (3) and forms a second pivot. The first pivot and the second pivot are coupled with the physiological motion axis of the subtalar joint. The third frame (5) is rotatably connected to the end of the second frame (4) away from the second pivot and forms the third pivot. Foot fixation device (6) is used to fix the patient's foot. The foot fixation device (6) is rotatably connected to the other end of the third frame (5) and forms a fourth pivot. The third pivot and the fourth pivot are coupled with the physiological motion axis of the tibiotalar joint. The drive chain (7) has multiple drive chains (7). The second frame (4) is connected to the base (1) through two drive chains (7) to form a first closed kinematic chain. The foot stabilizer (6) is connected to the base (1) through two drive chains (7) to form a second closed kinematic chain. Under the action of the first closed kinematic chain and the second closed kinematic chain, the foot stabilizer (6) can drive the foot to achieve dorsiflexion, plantarflexion, inversion, eversion and compound movements of the ankle joint.

2. The ankle joint rehabilitation robot with joint axis coupling according to claim 1, characterized in that, It also includes a calf support (8), which is obliquely fixed to the base (1) and close to the heel side of the foot fixation device (6), and the calf support (8) is detachably connected to an elastic leg strap (9).

3. The ankle joint rehabilitation robot with joint axis coupling according to claim 1, characterized in that, The drive chain (7) includes a connecting seat (71), a universal joint (72) and a telescopic push rod (73). The connecting seat (71) is fixedly connected to the base (1). There are two sets of universal joints (72) and they are respectively fixedly connected to the two ends of the telescopic push rod (73). The universal joint near the fixed end of the telescopic push rod (73) is rotatably connected to the connecting seat (71). The universal joint near the telescopic end of the telescopic push rod (73) is fixedly connected to the foot fastener (6) or the second frame (4). Based on the linear extension and retraction of the two drive chains (7), the spatial position of the first closed kinematic chain or the second closed kinematic chain can be changed.

4. The ankle joint rehabilitation robot with joint axis coupling according to claim 3, characterized in that, The linear extension and retraction of the drive branch corresponding to the first closed kinematic chain can act on the second frame (4) relative to the base (1) around the first and second rotating axes in a compound motion. Based on the movement of the second frame, the linear extension and retraction of the drive branch corresponding to the second closed kinematic chain can act on the foot retainer (6) relative to the second frame (4) around the third and fourth rotating axes in a compound motion.

5. The ankle joint rehabilitation robot with joint axis coupling according to claim 1, characterized in that, The first rotating axis intersects the second rotating axis perpendicularly, and the third rotating axis intersects the fourth rotating axis perpendicularly. The first rotating axis, the second rotating axis, the third rotating axis, and the fourth rotating axis work together to form a coupled motion axis consistent with the human ankle joint.

6. The ankle joint rehabilitation robot with joint axis coupling according to claim 1, characterized in that, The foot restraint (6) includes a foot pedal (61), an elastic foot strap (62), a universal joint fixing seat (63), and connecting lugs (64). The elastic foot strap (62) is detachably connected to the middle of both sides of the foot pedal (61). The universal joint fixing seat (63) is fixedly installed on the middle of the bottom side of the foot pedal (61). There are two sets of connecting lugs (64), which are respectively fixed to the two ends of the foot pedal (61) near the heel. The foot restraint (6) is rotatably connected to the third frame (5) through the two sets of connecting lugs (64).

7. The ankle joint rehabilitation robot with joint axis coupling according to claim 1, characterized in that, The second frame (4) is fixedly provided with a drive branch connecting seat (10) at one end away from the second rotating shaft. The drive branch connecting seat (10) is used to fix one end of the two drive branches corresponding to the first closed motion chain, and the other end of the two drive branches corresponding to the first closed motion chain is fixedly connected to the base (1).

8. The ankle joint rehabilitation robot with joint axis coupling according to claim 1, characterized in that, The two drive chains corresponding to the first closed kinematic chain are located on both sides of the support (2).

9. The ankle joint rehabilitation robot with joint axis coupling according to claim 1, characterized in that, The first closed kinematic chain and the second closed kinematic chain are staggered on the base (1).

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