Four-degree-of-freedom series-parallel ankle joint rehabilitation mechanism

Abstract

The invention relates to the field of biological medicine industry, in particular to the field of physical therapy devices, and particularly relates to a four-degree-of-freedom series-parallel ankle joint rehabilitation mechanism. The parallel mechanism with one degree of freedom being two rotations and one movement is connected with the rotation pair in a series-parallel mode to achieve three rotations, one movement and four degrees of freedom of the movable platform, the rotation center of the movable platform coincides with the rotation center of the ankle joint all the time, and the manufacturing cost and the design calculation difficulty are effectively reduced; the ankle joint rehabilitation device is used for achieving ankle joint rehabilitation exercises such as ankle three-dimensional rotation and traction exercises.

Description

Technical Field

[0001] The present invention relates to the field of biomedicine industry, specifically to the field of physical therapy devices, and in particular to a four-degree-of-freedom hybrid ankle joint rehabilitation mechanism. Background Art

[0002] The ankle joint is an important hub and load-bearing joint for human movement, and it is very easy to sprain the ankle joint in daily life. Rehabilitation training after ankle sprain is the most effective treatment method. Traditional rehabilitation training is conducted one-on-one by medical staff, which is not only labor-intensive and wasteful, but also inefficient. With the rapid development of rehabilitation institutions, ankle rehabilitation institutions can not only improve the efficiency of rehabilitation training and reduce the workload of medical staff, but also enable ankle joint tissue to recover as soon as possible through regular and appropriate rehabilitation exercises, which has good commercial value and engineering application prospects.

[0003] By studying the current status of ankle rehabilitation robots at home and abroad, we found the following problems: First, although the rehabilitation robots currently studied can meet the rehabilitation needs of ankle joints, the degrees of freedom of rehabilitation robots are still mainly 2 to 3. For different types of ankle injuries, the degrees of freedom of ankle rehabilitation robots are insufficient; second, although the functions of ankle rehabilitation robots are relatively complete, the manufacturing cost is high and it is not easy to promote and use; third, the rehabilitation effect of ankle rehabilitation robots is still poor, and the rehabilitation performance of rehabilitation robots needs to be further improved. The present invention starts from these problems, improves its overall cost-effectiveness and plays a promoting role. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a four-degree-of-freedom hybrid ankle joint rehabilitation mechanism, which can realize four basic rehabilitation movements of the ankle joint, namely: plantar flexion and dorsiflexion, adduction and abduction, inversion and eversion, and stretching rehabilitation movements, further improving the performance of the ankle joint rehabilitation robot while reducing the manufacturing cost.

[0005] To achieve the above-mentioned objectives, the present invention provides a four-degree-of-freedom hybrid ankle joint rehabilitation mechanism, including a fixed bracket, a moving platform, a front drive branch chain, a rear drive branch chain and a rotating platform, the front drive branch chain is provided with a drive unit, the rear drive branch chain is provided with two drive units, the three drive units are respectively connected to the moving platform through hinges, and are connected to the fixed bracket through a three-way connector.

[0006] The fixed bracket includes a three-way connector and a connecting rod, wherein the connecting rod is connected through the three-way connector to form a basic fixed bracket unit with a triangle as the basic structural shape, and the two basic fixed bracket units are respectively connected to the connecting rod slide rails of the front drive branch chain and the rear drive branch chain through the three-way connector to form a triangular prism stable support structure.

[0007] The dynamic platform includes a ball hinge, a foot pedal and a fixed connection port, wherein the ball hinge is welded to the foot pedal, and the two ends of the ball hinge and its connector form a ball hinge structure, which is conducive to the directional movement of the dynamic platform and effectively increases the flexibility of plantar flexion and dorsiflexion, adduction and abduction, inversion and eversion as well as stretching rehabilitation exercises. The fixed connection port runs through the foot pedal, and a strap is passed through the fixed connection port to facilitate the patient to securely fix the foot, thereby greatly enhancing the reliability of the mechanism.

[0008] The front drive branch chain is a PU type passive constraint branch chain, including a front drive connecting rod slide rail, a front drive movable slider and a front drive connecting member, wherein the front drive connecting member is arranged on the front drive movable slider and is connected through a rotating pair R1, the front drive movable slider is connected to the front drive connecting rod slide rail through a movable pair P1, the front drive connecting member follows the front drive movable slider to perform vertical translation movement on the front drive connecting rod slide rail, the front drive connecting member is connected to the connecting hinge through two series-connected rotating pairs R2 to form an equivalent universal joint U, the connecting hinge rotates stably at the connection with the front drive connecting member, the front drive connecting member is connected to the front drive movable slider through the rotating pair R1, rotates axially along the connection, and can adjust the left and right inclination angles of the moving platform near one end of the front drive branch chain, effectively increasing the flexibility of inversion, eversion and stretching rehabilitation exercises, the front drive connecting member is a semicircular wall, and is installed on both sides of the semicircular ring of the front drive connecting member with the connecting hinge, effectively limiting its degree of freedom and making the movement more stable.

[0009] The rear drive branch chain is two CRS type active unconstrained branch chains, including a rear drive ball hinge, a universal joint, a rear drive movable slider and a rear drive connecting rod slide rail, wherein the rear drive ball hinge is connected to the rear drive movable slider through a universal joint, the rear drive ball hinge performs directional swinging motion within the mechanism through the universal joint, the rear drive movable slider is connected to the rear drive connecting rod slide rail through a moving pair P2, and the rear drive movable slider performs vertical translation motion on the rear drive connecting rod slide rail, and the two CRS type active unconstrained branch chains are respectively located on the adjacent two sides of the fixed bracket, and the two CRS type active unconstrained branch chains do not move in unison from time to time, and the left and right and up and down inclination angles of the moving platform near the end of the rear drive branch chain can be changed, effectively increasing the flexibility of plantar flexion and dorsiflexion, adduction and abduction, inversion and eversion, and stretching rehabilitation exercises.

[0010] The front drive branch chain is provided with a driving unit, and the front drive branch chain is connected to the moving platform through a connecting hinge with a rotating pair R2. The two connecting hinges swing synchronously through the rotating pair, and the up and down inclination angles of the moving platform near the end of the front drive branch chain are smoothly changed, effectively increasing the flexibility of plantar flexion, dorsiflexion, adduction and abduction, and stretching rehabilitation exercises.

[0011] The rear drive branch chain is provided with two drive units, and the structures and connection methods of the two drive branches are exactly the same. The two drive units of the rear drive branch chain are connected through a rear drive ball joint and a ball joint, so that the movement direction of the dynamic platform is changeable and has good flexibility.

[0012] The extended lines of the axes of the two revolute pairs R2 and the extended lines of the axes of the revolute pair R1 always intersect at one point, that is, the point is the rotation center of the human ankle joint. The rotation center can always coincide with the rotation center of the ankle joint, and the movement is more standardized.

[0013] The rear drive branch chain is connected to the moving platform via a ball joint structure, and the inclination angle of the moving platform at one end of the rear drive branch chain can be adjusted. The front drive branch chain is connected to the moving platform via a rotating pair R2, and the inclination angle of the moving platform at one end of the front drive branch chain can be adjusted, and has the function of adjusting the inclination angle.

[0014] The rotating platform constitutes a rotating pair R3, the fixed bracket 1 is fixed on the rotating platform, the rotating platform can rotate along the Z-axis direction, and the rotating platform is provided with an angle limiter, and the threshold of the limiter is from negative 30° to positive 30°.

[0015] The present invention discloses a four-degree-of-freedom hybrid ankle joint rehabilitation mechanism, which has the following beneficial effects: the mechanism is a four-degree-of-freedom hybrid mechanism with hybrid driving characteristics, which can realize the rotational freedom in four directions of ankle joint plantar flexion and dorsiflexion, adduction and abduction, inversion and eversion, and stretching rehabilitation movement; the three branches are respectively a PU-type passive constraint branch and two CRS-type active unconstrained branches, and the axis extension lines of the three rotating pairs intersect at a point, which is the rotation center of the human ankle joint, so that the rotation center of the mechanism coincides with the rotation center of the ankle, and it has high flexibility and low cost; it has an inclination adjustable support function, so that the mechanism can adapt to different conditions of different patients and adjust the angle of the mechanism to achieve the best rehabilitation effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the overall structure of a four-degree-of-freedom hybrid ankle joint rehabilitation mechanism; Figure 2 It is a schematic diagram of the equivalent mechanism of a four-degree-of-freedom hybrid ankle joint rehabilitation mechanism; Figure 3 It is a schematic diagram of the fixed bracket structure of a four-degree-of-freedom hybrid ankle joint rehabilitation mechanism; Figure 4 It is a schematic diagram of the structure of a dynamic platform of a four-degree-of-freedom hybrid ankle joint rehabilitation mechanism; Figure 5 It is a schematic diagram of the front drive branch chain structure of a four-degree-of-freedom hybrid ankle joint rehabilitation mechanism; Figure 6 It is a schematic diagram of the rear drive branch chain structure of a four-degree-of-freedom hybrid ankle joint rehabilitation mechanism; Figure 7 It is a schematic diagram of the inversion / external rotation angle of a four-degree-of-freedom hybrid ankle joint rehabilitation mechanism; Figure 8It is a schematic diagram of the adduction / abduction angle of a four-degree-of-freedom hybrid ankle joint rehabilitation mechanism; Fig. 9 It is a schematic diagram of the flexion / dorsiextension angle of a four-degree-of-freedom hybrid ankle joint rehabilitation mechanism; Fig.10 It is a schematic diagram of the inversion / valgus angular acceleration of a four-degree-of-freedom hybrid ankle joint rehabilitation mechanism; Fig.11 It is a schematic diagram of the flexion / dorsiextension angle acceleration of a four-degree-of-freedom hybrid ankle joint rehabilitation mechanism; Fig.12 It is a schematic diagram of the inversion / valgus angular acceleration of a four-degree-of-freedom hybrid ankle joint rehabilitation mechanism; Main reference numerals: Figure 1 Middle: 1 fixed bracket; 2 moving platform; 3 front drive branch chain; 4 rear drive branch chain; 5 rotating platform; Figure 3 Middle: 1-1 three-way connector; 1-2 connecting rod; Figure 4 Middle: 2-1 ball hinge; 2-2 foot pedal; 2-3 fixed connection port; 2-4 connecting hinge; Figure 5 Middle: 3-1 front drive connecting rod slide rail; 3-2 front drive moving slide block; 3-3 front drive connecting piece; Figure 6 Middle: 4-1 rear drive ball hinge; 4-2 universal joint; 4-3 rear drive moving slider; 4-4 rear drive connecting rod slide rail; DETAILED DESCRIPTION

[0017] In order to further understand the four-degree-of-freedom hybrid ankle joint rehabilitation mechanism provided by the present invention, the present invention is specifically described below in conjunction with the accompanying drawings and detailed embodiments.

[0018] refer to Figures 1 to 6 The present invention provides a four-degree-of-freedom hybrid ankle joint rehabilitation mechanism, comprising a fixed bracket 1, a moving platform 2, a front drive branch chain 3, a rear drive branch chain 4 and a rotating platform 5, wherein the front drive branch chain 3 is provided with a drive unit, and the rear drive branch chain 4 is provided with two drive units, and the three drive units are respectively connected to the moving platform 2 through hinges, and connected to the fixed bracket 1 through a three-way connector 1-1.

[0019] In this embodiment, the fixed bracket 1 includes a three-way connector 1-1 and a connecting rod 1-2, forming a basic fixed bracket unit with a triangle as the basic structural shape. The two basic fixed bracket units are respectively connected to the connecting rod slide rails of the front drive branch chain 3 and the rear drive branch chain 4 through the three-way connector 1-1 to form a triangular prism stable support structure, which effectively increases the stability and rigidity of the mechanism.

[0020] In this embodiment, the moving platform 2 includes a ball hinge 2-1, a foot pedal 2-2 and a fixed connection port 2-3, wherein the ball hinge 2-1 is welded to the foot pedal 2-2, and the two ends of the ball hinge 2-1 and its connector form a ball hinge structure, which is conducive to the directional movement of the moving platform 2, and effectively increases the flexibility of plantar flexion and dorsiflexion, adduction and abduction, inversion and eversion, and stretching rehabilitation exercises. The fixed connection port 2-3 runs through the foot pedal 2-2, and a strap is passed through the fixed connection port 2-3 to facilitate the patient to securely fix the foot, thereby greatly enhancing the reliability of the mechanism.

[0021] In this embodiment, the front drive branch chain 3 is a PU type passive constraint branch chain, including a front drive link rail 3-1, a front drive movable slider 3-2 and a front drive connecting member 3-3, wherein the front drive connecting member 3-3 is arranged on the front drive movable slider 3-2, connected by a rotation pair R1, the front drive movable slider 3-2 is connected to the front drive movable slide rail 3-1 through a movable pair P1, the front drive connecting member 3-3 follows the front drive movable slider 3-2 to perform vertical translation movement on the front drive link rail 3-1, and the front drive connecting member 3-3 is connected to the connecting rod 3-1 through two rotating pairs R2 in series. The connecting hinges 2-4 are connected to form an equivalent universal joint U. The connecting hinge 2-4 rotates stably at the connection with the front drive connector 3-3. The front drive connector 3-3 is connected to the front drive movable slider 3-2 through a rotating pair R1, and rotates axially along the connection. The left and right inclination angles of the moving platform 2 near one end of the front drive branch chain 3 can be adjusted, effectively increasing the flexibility of inversion, eversion and stretching rehabilitation exercises. The front drive connector 3-3 is semicircular and is installed on both sides of the semicircular ring of the front drive connector 3-3 symmetrically with the connecting hinge 2-4, which effectively limits its degree of freedom and makes the movement more stable.

[0022] In this embodiment, the rear drive branch chain 4 is provided with two drive units, the structures and connection methods of the two drive units are exactly the same, but the movement directions are not always consistent, so different inclination angles are formed relative to the moving platform 2, increasing the flexibility of varus and valgus rehabilitation exercises.

[0023] In this embodiment, the rear drive branch chain 4 is two CRS type active unconstrained branch chains, including a rear drive ball hinge 4-1, a universal joint 4-2, a rear drive movable slider 4-3 and a rear drive connecting rod slide rail 4-4, wherein the rear drive ball hinge 4-1 is connected to the rear drive movable slider 4-3 through the universal joint 4-2, the rear drive ball hinge 4-1 performs directional swinging motion in the mechanism through the universal joint 4-2, the rear drive movable slider 4-3 is connected to the rear drive connecting rod slide rail 4-4 through the mobile pair P2, and the rear drive movable slider 4-3 performs vertical translation motion on the rear drive connecting rod slide rail 4-4. The two CRS type active unconstrained branch chains are respectively located on the adjacent two sides of the fixed bracket 1, and the two CRS type active unconstrained branch chains do not move uniformly from time to time, and the left and right and up and down inclination angles of the moving platform 2 near the end of the rear drive branch chain 4 can be changed, effectively increasing the flexibility of plantar flexion and dorsiflexion, adduction and abduction, inversion and eversion, and stretching rehabilitation exercises.

[0024] In this embodiment, the rear drive branch chain 4 is connected to the moving platform 2 by a rear drive ball joint 4-1 with a ball joint structure, and the inclination angle of the moving platform 2 at one end of the rear drive branch chain 4 can be adjusted. The front drive branch chain 3 is connected to the moving platform 2 by a rotating pair, and the inclination angle of the moving platform 2 at one end of the front drive branch chain 3 can be adjusted, and has the function of adjusting the inclination angle.

[0025] In this embodiment, the extended lines of the axes of the two revolute pairs R2 and the extended lines of the axes of the revolute pair R1 always intersect at one point, which is also the rotation center of the human ankle joint, that is, the rotation center of the mechanism can always coincide with the rotation center of the ankle joint.

[0026] Because the 2-CRS-PU parallel mechanism has three degrees of freedom, the rotation of the X and Y axes of the orbiting platform 2 and the movement along the vertical axis of the fixed bracket 1 is a parallel mechanism with two degrees of freedom and one translation. By mixing a rotation pair R, a rotation of the Z axis of the orbiting platform 2 is added, thereby realizing the three rotations and one translation movement of the four-degree-of-freedom hybrid ankle joint rehabilitation mechanism, namely: the rotation of the X, Y, and Z axes of the orbiting platform 2 and the movement along the vertical axis of the fixed bracket 1. Such a mechanism has fewer components, low manufacturing cost and better rehabilitation performance.

[0027] refer to Figures 7 to 12Based on the theoretical derivation of spatial mechanism analysis and configuration synthesis of a four-degree-of-freedom hybrid ankle rehabilitation mechanism, the rod length, stroke length and spatial angle of the front drive branch chain 3 and the rear drive branch chain 4 are reasonably selected to achieve the ankle rehabilitation working space of: inversion / valgus 0° to 20°, adduction / abduction 0° to 30°, and toe flexion / dorsiflexion 4° to 27°. The stroke time of inversion / valgus and toe flexion / dorsiflexion rehabilitation movement is 5 seconds, and its angle is the angle between the foot pedal 2 and the horizontal position. The stroke time of adduction / abduction rehabilitation movement is 5 seconds, and its angle is the Z-axis angle between the foot pedal and the fixed bracket 1. The angles reached by various movement modes are all within the required range. The angular acceleration curves of inversion / valgus, adduction / abduction, and toe flexion / dorsiflexion change smoothly and continuously, without interruption points and mutation points, which proves that the mechanism moves smoothly.

[0028] When the present invention is used for ankle joint rehabilitation training, the patient places the foot on the dynamic platform, and the push rods of the front drive branch chain and the rear drive branch chain are moved to realize the rotation of the ankle joint in four directions, namely, plantar flexion and dorsiflexion, adduction and abduction, inversion and eversion, and stretching rehabilitation exercise. The rotation center of the mechanism is the rotation center of the ankle joint, and the inclination angle can be adjusted to change the overall angle of the mechanism, so that the patient can achieve the best training effect.

[0029] The above-described embodiments are only for describing the specific implementation of the present invention, and are not intended to limit the concept and scope of the present invention. Without departing from the design concept of the present invention, various modifications and improvements made by ordinary persons in the art to the technical solution of the present invention should fall within the protection scope of the present invention, and the technical contents for which the present invention is requested to be protected have been fully recorded in the claims.

Claims

1. A four-degree-of-freedom hybrid ankle joint rehabilitation mechanism, characterized in that: The mechanism comprises a fixed support (1), a moving platform (2), a front drive branch chain (3), a rear drive branch chain (4) and a rotating platform (5); the fixed support (1) is fixedly connected to the rotating platform (5); the fixed support (1) is arranged in an equilateral triangle with three drive branches having the same stroke; and the moving platform (2) is connected to the drive branch chain via a hinge.

2. A four-degree-of-freedom hybrid ankle joint rehabilitation mechanism according to claim 1, characterized in that: The fixed bracket (1) comprises a three-way connector (1-1) and a connecting rod (1-2), wherein the connecting rod (1-2) is connected via the three-way connector (1-1) to form a basic fixed bracket unit, and two basic fixed bracket units are connected to the connecting rod slide rails of the front drive branch chain (3) and the rear drive branch chain (4) via the three-way connector (1-1) to form a complete fixed bracket (1).

3. A four-degree-of-freedom hybrid ankle joint rehabilitation mechanism according to claim 1, characterized in that: The moving platform (2) comprises a ball hinge (2-1), a foot pedal (2-2), a fixed connection port (2-3) and a connection hinge (2-4), wherein the ball hinge (2-1) is welded to the foot pedal (2-2), the fixed connection port (2-3) penetrates the foot pedal (2-2), and the patient's foot is stably fixed to the mechanism via the fixed connection port (2-3).

4. A four-degree-of-freedom hybrid ankle joint rehabilitation mechanism according to claim 1, characterized in that: The front drive branch chain (3) is a PU type passive constraint branch chain, comprising a front drive connecting rod slide rail (3-1), a front drive movable slider (3-2) and a front drive connecting member (3-3), wherein the front drive connecting member (3-3) is arranged on the front drive movable slider (3-2) and is connected via a rotation pair R1, the front drive movable slider (3-2) is connected to the front drive connecting rod slide rail (3-1) via a movable pair P1, and the front drive connecting member (3-3) is connected to a connecting hinge (2-4) via two serially connected rotation pairs R2 to form an equivalent universal pair U.

5. The four-degree-of-freedom hybrid ankle joint rehabilitation mechanism according to claim 1, characterized in that: The rear drive branch chain (4) is a CRS type active unconstrained branch chain, comprising a rear drive ball hinge (4-1), a universal joint (4-2), a rear drive movable slider (4-3) and a rear drive connecting rod slide rail (4-4), wherein the rear drive ball hinge (4-1) and the rear drive movable slider (4-3) are connected via a universal joint (4-2), the universal joint (4-2) and the rear drive movable slider (4-3) form an equivalent cylindrical pair C1, and the rear drive movable slider (4-3) is connected to the rear drive connecting rod slide rail (4-4) via a movable pair P2.

6. A four-degree-of-freedom hybrid ankle joint rehabilitation mechanism according to claim 1, characterized in that: The rotating platform (5) forms a rotating pair R3, the fixed bracket 1 is fixed on the rotating platform (5), the rotating platform (5) can rotate along the Z-axis direction, and the rotating platform (5) is provided with an angle limiter, and the threshold of the limiter is from negative 30° to positive 30°.

7. The four-degree-of-freedom hybrid ankle joint rehabilitation mechanism according to claim 1, characterized in that: The rear drive branch chain (4) has two drive units, the two drive units have the same structure and connection method, the front drive branch chain (3) is provided with a drive unit, the front drive branch chain (3) is connected to the moving platform (2) through a front drive connecting hinge (2-4) with a rotation pair R2, and the independence of the two drive branches increases their movement form.

8. The four-degree-of-freedom hybrid ankle joint rehabilitation mechanism according to claim 1, characterized in that: The rear drive branch chain (4) is connected to the moving platform (2) via a ball joint structure, and the front drive branch chain (3) is connected to the moving platform (2) via a revolving pair R2, so that the movement of the front drive branch chain (3) and the rear drive branch chain (4) relative to the moving platform (2) are combined.

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