Ankle joint active rehabilitation training device based on variable stiffness mechanism

Abstract

The application discloses an ankle joint active rehabilitation training device based on a variable stiffness mechanism, which comprises a platform assembly, a base, a spherical parallel mechanism and a stiffness adjusting module. The platform assembly comprises a foot support, a bandage and a platform. The foot support is located on the platform, and the bandage is located on the top of the foot support to provide support and fixing functions for the human foot and can follow the active rehabilitation training movement of the human ankle joint. The base is fixed on the ground and always keeps a stationary state during the rehabilitation training process. The spherical parallel unit is connected between the platform and the base to provide three degrees of freedom spherical rotation movement for the platform assembly. The stiffness adjusting unit comprises a driving unit and an elastic unit and is connected between the platform and the base to provide adjustable impedance force / torque for the platform assembly.

Description

Technical Field

[0001] This invention belongs to the field of medical device technology, specifically relating to an active rehabilitation training device for the ankle joint based on a variable stiffness mechanism. Background Technology

[0002] The ankle joint is composed of the articular surfaces of the distal ends of the tibia and fibula of the lower leg and the trochlea of ​​the talus. Under normal circumstances, it can freely rotate in three directions: plantar flexion / dorsiflexion, inversion / eversion, and internal / external rotation. Therefore, as an important physiological joint in contact with the support surface of the body, the ankle joint plays a crucial role in maintaining balance during walking and standing. However, the ankle joint is easily injured by non-physiological movements in daily life, which can not only affect normal activities but also potentially impact the normal function of other parts of the body, such as the lower limbs, pelvis, and spine. Currently, ankle rehabilitation training mainly relies on physical therapists to reconstruct the connection between the limb and the damaged central nervous system, thereby increasing the chances of restoring motor function. However, this traditional physical therapy method, which relies on physical therapists, has the following problems: high physical exertion, high skill requirements, and long rehabilitation periods. Therefore, rehabilitation robots are gradually becoming a feasible option for clinical rehabilitation treatment. Currently, various ankle rehabilitation training devices developed domestically and internationally have varying degrees of problems.

[0003] 1. Most ankle rehabilitation equipment is designed for single-degree-of-freedom training exercises such as toe flexion / dorsiflexion, which is incompatible with the multi-directional rotational movements of the human ankle joint (toe flexion / dorsiflexion, inversion / eversion, internal rotation, external rotation), thus reducing the effectiveness and safety of interactive training.

[0004] 2. Some existing active ankle rehabilitation training devices have a narrow resistance adjustment bandwidth, which makes it difficult to cover the range of changes in resistance / torque during human rehabilitation training, thus reducing the effectiveness of rehabilitation training.

[0005] 3. Most ankle rehabilitation training equipment uses rigid body transmission, which has poor flexibility and is prone to generating harmful impacts during training, leading to sudden changes in human-machine interaction force / torque and deviation of human-machine movement trajectory, which is not conducive to safe and effective rehabilitation training.

[0006] 4. Existing ankle rehabilitation equipment has a complex structure and control system, resulting in high prices and making it difficult to promote and apply on a large scale. Summary of the Invention

[0007] The purpose of this invention is to solve the above-mentioned problems and provide an active rehabilitation training device for the ankle joint based on a variable stiffness mechanism, which can provide multi-directional, wide-range adjustable resistance active-resistance rehabilitation training by fitting the three-degree-of-freedom rotational motion of the human ankle joint. It has a simple structure and is easy to control.

[0008] To solve the above-mentioned technical problems, the technical solution of the present invention is: an active ankle rehabilitation training device based on a variable stiffness mechanism, comprising a platform assembly, a base, a spherical parallel mechanism, and a stiffness adjustment module. The platform assembly includes a footrest, a strap, and a platform. The footrest is located on the platform, and the strap is located on top of the footrest, providing support and fixation for the human foot and enabling active rehabilitation training exercises following the human ankle joint. The base is fixed to the ground and remains stationary throughout the rehabilitation training process. The spherical parallel structure connects the platform and the base, providing the platform assembly with three degrees of freedom of spherical rotation. The stiffness adjustment unit includes a drive unit and an elastic unit, connected between the platform and the base, providing the platform assembly with adjustable resistance / torque.

[0009] Preferably, the footrest has a hollow, shoe-shaped structure and is fixedly installed at the center of the platform plane. The straps can secure the user's feet to the footrest with appropriate tightness.

[0010] Preferably, the spherical parallel mechanism includes an upper adapter plate, a lower adapter plate, and a connecting rod assembly. The connecting rod assembly includes an upper connecting rod, a lower connecting rod, and a pin. There are three sets of connecting rod assemblies, which are arranged symmetrically in space around the central axis of the base at 120°. One end of the upper connecting rod is connected to the upper adapter plate, and the other end is connected to one end of the lower connecting rod through the pin. The other end of the lower connecting rod is connected to the lower adapter plate. The adapter plate on the spherical parallel mechanism is fixedly connected to the platform, and the lower adapter plate is fixedly connected to the base.

[0011] Preferably, the upper adapter plate has a triangular cross-section with a circular through hole in the middle, and the upper connecting rod in each connecting rod assembly is rotatably connected to one end of the upper adapter plate.

[0012] Preferably, the lower adapter plate has a triangular cross-section, a triangular through hole in the middle, and the ends of the lower adapter plate are rotatably connected to the lower connecting rod in each group of connecting rod assemblies.

[0013] Preferably, the platform assembly fixed to the spherical parallel mechanism can rotate in three degrees of freedom around the center of the intersection of the upper and lower connecting rod mounting axes, which can meet the movement requirements of the human ankle for plantar flexion / dorsiflexion, inversion / eversion, and internal / external rotation.

[0014] Preferably, the stiffness adjustment module includes a drive unit and an elastic unit. The drive unit includes a DC motor, a motor mounting flange, a crankshaft, and radial connecting rods arranged from top to bottom. The DC motor is fixed on the motor mounting flange, and the output shaft of the DC motor is inserted into and locked into the center hole of the crankshaft. The crankshaft protrudes outward to form four crankshaft mounting cams. There are four radial connecting rods, which are rod-shaped structures. The two ends of the radial connecting rods are respectively the large hole end and the small hole end. The large hole end of the radial connecting rod is connected to the crankshaft mounting cams around the crankshaft. The motor mounting flange is fixed to the lower adapter plate by fasteners; there are four sets of elastic units, arranged symmetrically around the central axis of the base at a 90° spatial rotation. The elastic unit includes an upper hinge block, a linear spring, a lower hinge block, a slider, and a guide rail. The upper hinge block is fixed to the platform. One end of the linear spring is connected to the upper hinge block, and the other end is connected to the lower hinge block. The lower hinge block is fixed to the slider. The slider is mounted on the guide rail and slidably connected. The guide rail is fixed to the base. The bottom of the lower hinge block protrudes outward to form a lower hinge block mounting convex shaft. The small hole end of the radial connecting rod is connected to the lower hinge block mounting convex shaft.

[0015] Preferably, the guide rail is arranged radially along the base. The DC motor drives the crank disk to rotate in both directions. The rotation of the crank disk will simultaneously drive the four sets of lower hinge blocks to move in a centripetal / centrifugal manner on the guide rail through the centripetal connecting rod. During this process, the distance between the upper and lower hinge blocks changes accordingly, causing the tension of the linear spring connecting the two to change accordingly, thereby realizing the stiffness adjustment function of the device.

[0016] The beneficial effects of this invention are:

[0017] 1. The present invention provides an active ankle joint rehabilitation training device based on a variable stiffness mechanism. The device uses a spherical parallel mechanism to simulate the movement trajectory of the human ankle joint. It can follow the ankle joint to achieve three degrees of freedom rotational movements of toe flexion / dorsiflexion, inversion / eversion and internal and external rotation, ensuring the comfort and safety of the rehabilitation process.

[0018] 2. The device of the present invention introduces an elastic unit, which makes the movement smoother, reduces the impact and vibration generated by rigid transmission, and prevents secondary damage to the ankle joint.

[0019] 3. This invention adjusts the tension of the elastic unit through a variable stiffness mechanism, which can apply a wide range of resistance force / torque on the platform, providing an adjustable resistance mode for the active movement exercise of the patient's ankle joint, which is beneficial to promoting the recovery of ankle joint muscle strength.

[0020] 4. The device of the present invention has a simple structure and can realize multi-directional motion and wide-range stiffness adjustment functions without complex mechanical structure and control system, which greatly reduces manufacturing costs and is easy to promote in the market. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of an active rehabilitation training device for the ankle joint based on a variable stiffness mechanism according to the present invention.

[0022] Figure 2 This is a schematic diagram of the structure of the platform components of the present invention;

[0023] Figure 3 This is a schematic diagram of the spherical parallel mechanism of the present invention;

[0024] Figure 4 This is a schematic diagram of the stiffness adjustment module mechanism of the present invention;

[0025] Figure 5 This is the present invention. Figure 4 A schematic diagram of the structure of part A;

[0026] Figure 6 This is a schematic diagram of the stiffness adjustment process of the present invention;

[0027] Figure 7 This is a schematic diagram of the overall structure of the present invention under the minimum stiffness state;

[0028] Figure 8 This is a schematic diagram of the overall structure of the present invention under the condition of maximum stiffness.

[0029] Explanation of reference numerals in the attached drawings: 1. Platform assembly; 2. Base; 3. Spherical parallel mechanism; 4. Stiffness adjustment unit; 11. Foot support; 12. Strap; 13. Platform; 31. Upper adapter plate; 32. Lower adapter plate; 33. Linkage assembly; 331. Upper connecting rod; 332. Lower connecting rod; 333. Pin; 41. Drive unit; 411. DC motor; 412. Motor mounting flange; 413. Crankshaft; 414. Radial connecting rod; 42. Elastic unit; 421. Upper hinge block; 422. Linear spring; 423. Lower hinge block; 424. Slider; 425. Guide rail. Detailed Implementation

[0030] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0031] like Figures 1 to 8As shown, this invention provides an active ankle rehabilitation training device based on a variable stiffness mechanism, comprising a platform assembly 1, a base 2, a spherical parallel mechanism 3, and a stiffness adjustment module 4. The platform assembly 1 includes a footrest 11, a strap 12, and a platform 13. The footrest 11 is located on the platform 13, and the strap 12 is located on top of the footrest 11, providing support and fixation for the human foot and enabling active rehabilitation training exercises following the ankle joint. The base 2 is fixed to the ground and remains stationary throughout the rehabilitation training process. The spherical parallel structure 3 connects the platform 13 and the base 2, providing the platform assembly 1 with three degrees of freedom of spherical rotation. The stiffness adjustment module 4 includes a drive unit 41 and an elastic unit 42, connected between the platform 13 and the base 2, providing the platform assembly 1 with adjustable resistance / torque.

[0032] The footrest 11 has a hollow, shoe-shaped structure and is fixedly installed at the center of the platform 13. The straps 12 can secure the user's feet to the footrest 11 with appropriate tightness.

[0033] In actual use, the footrest 11 can be specially designed to fit the size of the user's feet to better meet the user's comfort. The straps 12 can fix the user's feet to the footrest 11, and the tightness of the straps 12 can be adjusted to better fit the user's feet.

[0034] like Figure 3 As shown, the spherical parallel mechanism 3 includes an upper adapter plate 31, a lower adapter plate 32, and a connecting rod assembly 33. The connecting rod assembly 33 includes an upper connecting rod 331, a lower connecting rod 332, and a pin 333. There are three sets of connecting rod assemblies 33, which are arranged symmetrically in space at 120° around the central axis of the base 2. One end of the upper connecting rod 331 is connected to the upper adapter plate 31, and the other end is connected to one end of the lower connecting rod 332 through the pin 333. The other end of the lower connecting rod 332 is connected to the lower adapter plate 32. The adapter plate 31 on the spherical parallel mechanism 3 is fixedly connected to the platform 13, and the lower adapter plate 32 is fixedly connected to the base 2.

[0035] The upper adapter plate 31 has a triangular cross-section with a circular through hole in the middle. The upper connecting rod 331 in each connecting rod assembly 33 is rotatably connected to one end of the upper adapter plate 31.

[0036] In this embodiment, the end of the upper adapter plate 31 is a bent structure, and the connecting shaft passes through the end of the upper adapter plate 31 and the upper connecting rod 331, thereby rotatably connecting the upper connecting rod 331 and the upper adapter plate 31. The upper adapter plate 31 is fixed to the bottom of the platform 13 by bolts.

[0037] The lower adapter plate 32 has a triangular cross-section and a triangular through hole in the middle. The ends of the lower adapter plate 32 are rotatably connected to the lower connecting rod 332 in each group of connecting rod assemblies 33.

[0038] In this embodiment, a lower adapter plate connecting block is fixedly provided at the end of the lower adapter plate 32. The lower adapter plate connecting block is bent into a U-shaped structure. The connecting shaft passes through the top of the lower adapter plate connecting block and the lower connecting rod 332 and is rotatably connected. The bottom of the lower adapter plate connecting block is fixedly connected to the base 2 by bolts.

[0039] The platform assembly 1, which is fixedly connected to the spherical parallel mechanism 3, can rotate around the center of the circle at the intersection of the mounting axes of the upper connecting rod 331 and the lower connecting rod 332, and can meet the movement requirements of the human ankle for plantar flexion / dorsiflexion, inversion / eversion and internal / external rotation.

[0040] like Figure 4 As shown, the stiffness adjustment module 4 includes a drive unit 41 and an elastic unit 42. The drive unit 41 includes a DC motor 411, a motor mounting flange 412, a crank disc 413, and radial connecting rods 414 arranged from top to bottom. The DC motor 411 is fixed on the motor mounting flange 412, and the output shaft of the DC motor 411 is inserted into the center hole of the crank disc 413 and locked. The crank disc 413 protrudes outward to form four crank disc mounting cams. There are four radial connecting rods 414, which are rod-shaped structures. The two ends of the radial connecting rods 414 are the large hole end and the small hole end, respectively. The large hole end of the radial connecting rod is connected to the crank disc mounting cams around the crank disc 413. The motor mounting flange 412 is fixed to the lower adapter plate 32 by fasteners. There are four sets of elastic units 42, which are arranged in a 90° spatial rotational symmetry around the central axis of the base 2. Each elastic unit 42 includes an upper hinge block 421, a linear spring 422, a lower hinge block 423, a slider 424, and a guide rail 425. The upper hinge block 421 is fixedly connected to the platform 13. One end of the linear spring 422 is connected to the upper hinge block 421, and the other end is connected to the lower hinge block 423. The lower hinge block 423 is fixedly connected to the slider 424. The slider 424 is mounted on the guide rail 425 and is slidably connected. The guide rail 425 is fixedly connected to the base 2. The bottom of the lower hinge block 423 protrudes outward to form a lower hinge block mounting convex shaft. The small hole end of the radial connecting rod 414 is connected to the lower hinge block mounting convex shaft.

[0041] The guide rail 425 is arranged radially along the base 2. The DC motor 411 drives the crank disk 413 to rotate forward / reverse. The rotation of the crank disk 413 will simultaneously drive the four sets of lower hinge blocks 423 to move centrifugally / centrifugally on the guide rail 425 through the centripetal connecting rod 414. During this process, the distance between the upper hinge block 421 and the lower hinge block 423 changes accordingly, causing the tension of the linear spring 422 connected between them to change accordingly, thus realizing the stiffness adjustment function of the device.

[0042] To better understand the working principle of this invention, the working process and usage method of this invention will be described below: The working process of this invention includes a preparation process, a stiffness adjustment process, and a rehabilitation training process.

[0043] Preparation process: The user's feet are secured to the footrest 11 with the appropriate tightness of the straps 12 of the platform component 1.

[0044] Stiffness adjustment process: The resistance level of the active-resistance training phase is determined according to the patient's muscle strength level (MMT). The crank disk 413 is driven by the DC motor 411 to rotate forward / reverse, and the tension of the four linear springs 422 can be controlled at the same time, thereby adjusting the resistance force / torque of the platform.

[0045] Rehabilitation training process: Under the guidance of a rehabilitation therapist, the human body can actively exert force to control the ankle on the device platform 13 to perform single and compound rehabilitation exercises such as toe flexion / dorsiflexion, inversion / eversion, and internal rotation / external rotation, which promotes muscle strength recovery and enhancement and helps ankle joint rehabilitation.

[0046] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention, and should be understood that the scope of protection of the invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of this invention.

Claims

1. An active rehabilitation training device for the ankle joint based on a variable stiffness mechanism, characterized in that: It includes a platform component (1), a base (2), a spherical parallel mechanism (3) and a stiffness adjustment unit (4). The platform component (1) includes a footrest (11), a strap (12) and a platform (13). The footrest (11) is located on the platform (13), and the strap (12) is located on top of the footrest (11). It provides support and fixation for the human foot and can follow the human ankle joint to perform active rehabilitation training exercises. The base (2) is fixed on the ground and remains stationary throughout the rehabilitation training process; the spherical parallel mechanism (3) is connected between the platform (13) and the base (2) to provide the platform assembly (1) with three degrees of freedom of spherical rotational motion; the stiffness adjustment unit (4) includes a drive unit (41) and an elastic unit (42), which is connected between the platform (13) and the base (2) and can provide the platform assembly (1) with adjustable resistance force / torque; The spherical parallel mechanism (3) includes an upper adapter plate (31), a lower adapter plate (32), and a connecting rod assembly (33). The connecting rod assembly (33) includes an upper connecting rod (331), a lower connecting rod (332), and a pin (333). There are three sets of connecting rod assemblies (33), which are arranged symmetrically in space around the central axis of the base (2) at 120°. One end of the upper connecting rod (331) is connected to the upper adapter plate (31), and the other end is connected to one end of the lower connecting rod (332) through the pin (333). The other end of the lower connecting rod (332) is connected to the lower adapter plate (32). The adapter plate (31) on the spherical parallel mechanism (3) is fixedly connected to the platform (13), and the lower adapter plate (32) is fixedly connected to the base (2). The lower adapter plate (32) is fixedly provided with a lower adapter plate connecting block at its end. The lower adapter plate connecting block is bent into a U-shaped structure. The connecting shaft passes through the top of the lower adapter plate connecting block and the lower connecting rod (332) and is rotatably connected. The bottom of the lower adapter plate connecting block is fixedly connected to the base (2) by bolts. The drive unit (41) includes, from top to bottom, a DC motor (411), a motor mounting flange (412), a crank disc (413), and radial connecting rods (414). The DC motor (411) is fixed on the motor mounting flange (412). The output shaft of the DC motor (411) is inserted into the center hole of the crank disc (413) and locked. The crank disc (413) protrudes outward to form four crank disc mounting cams. There are four radial connecting rods (414). The radial connecting rods (414) are rod-shaped structures. The two ends of the radial connecting rods (414) are the large hole end and the small hole end, respectively. The large hole end of the radial connecting rod is connected to the crank disc mounting cams around the crank disc (413). The motor mounting flange (412) is fixed to the lower adapter plate (32) by fasteners. There are four sets of elastic units (42), which are arranged in a 90° spatial rotational symmetry around the central axis of the base (2). The elastic unit (42) includes an upper hinge block (421), a linear spring (422), a lower hinge block (423), a slider (424), and a guide rail (425). The upper hinge block (421) is fixedly connected to the platform (13). One end of the linear spring (422) is connected to the upper hinge block (421), and the other end is connected to the lower hinge block (423). The lower hinge block (423) is fixedly connected to the slider (424). The slider (424) is installed on the guide rail (425) and slidably connected. The guide rail (425) is fixedly connected to the base (2). The bottom of the lower hinge block (423) protrudes outward to form a lower hinge block mounting convex shaft. The small hole end of the centripetal connecting rod (414) is connected to the lower hinge block mounting convex shaft.

2. The ankle joint active rehabilitation training device based on a variable stiffness mechanism according to claim 1, characterized in that: The footrest (11) has a hollow structure shaped like a shoe. The footrest (11) is fixedly installed at the center of the plane of the platform (13). The strap (12) can fix the user's foot to the footrest (11) with appropriate tightness.

3. The ankle joint active rehabilitation training device based on a variable stiffness mechanism according to claim 1, characterized in that: The upper adapter plate (31) has a triangular cross-section and a circular through hole in the middle. The upper connecting rod (331) in each connecting rod assembly (33) is rotatably connected to one end of the upper adapter plate (31).

4. The ankle joint active rehabilitation training device based on a variable stiffness mechanism according to claim 1, characterized in that: The lower adapter plate (32) has a triangular cross-section and a triangular through hole in the middle. The ends of the lower adapter plate (32) are rotatably connected to the lower connecting rod (332) in each group of connecting rod assemblies (33).

5. The ankle joint active rehabilitation training device based on a variable stiffness mechanism according to claim 1, characterized in that: The platform assembly (1), which is fixed to the spherical parallel mechanism (3), can rotate around the center of the circle at the intersection of the upper connecting rod (331) and the lower connecting rod (332) mounting axes, and can meet the movement requirements of the human ankle for plantar flexion / dorsiflexion, inversion / eversion and internal / external rotation.

6. The ankle joint active rehabilitation training device based on a variable stiffness mechanism according to claim 1, characterized in that: The guide rail (425) is arranged radially along the base (2). The DC motor (411) drives the crank disk (413) to rotate forward / backward. The rotation of the crank disk (413) will simultaneously drive the four sets of lower hinge blocks (423) to move centrifugally / centrifugally on the guide rail (425) through the centripetal connecting rod (414). During this process, the distance between the upper hinge block (421) and the lower hinge block (423) changes accordingly, causing the tension of the linear spring (422) connected between them to change accordingly, thus realizing the stiffness adjustment function of the device.

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