Three-degree-of-freedom parallel mechanism for lower limb rehabilitation

Abstract

The present invention provides a three-degree-of-freedom parallel mechanism for lower limb rehabilitation, which has a simple structure, good rigidity and does not contain a ball joint. It includes a fixed base and a moving platform, the fixed base is connected to the moving platform through a first branch chain, a second branch chain and a third branch chain, the first branch chain has the same structure as the second branch chain and both sequentially include a moving pair, a rotating pair, a connecting rod and a universal pair connected between the fixed base and the moving platform; the third branch chain includes a moving pair, a universal pair, a connecting rod and a universal pair; the axes of the moving pair in each branch chain are parallel to each other, the rotating pair axes of the first branch chain and the second branch chain are perpendicular to the moving pair axis, and the first rotating axis of the first universal pair of the third branch chain is parallel to the moving pair axis; in the first branch chain and the second branch chain, the second rotating axes of the two universal pairs are coaxial, and the rotating axes of the two rotating pairs are parallel to each other.

Description

Technical Field

[0001] The present invention relates to the technical field of lower limb rehabilitation equipment, and in particular to a three-degree-of-freedom parallel mechanism for lower limb rehabilitation. Background Art

[0002] At present, most traditional lower limb rehabilitation robots are serial structures, and the serial nodes correspond to the lower limb joints of the human body. The structure is simple, and each joint is driven independently without coupling. It has the advantages of simple kinematic solutions, easy control, and large workspace. Based on the above advantages, the mature serial mechanism has been widely used in the field of rehabilitation robots. However, due to the open-loop structure of the serial mechanism, the deformation and error between each joint will accumulate, resulting in a decrease in the overall stiffness and accuracy of the robot; in addition, the axis of the serial node and the axis of the human joint will deviate with the movement of the mechanism, causing secondary damage to the limbs. Therefore, under the conditions of the aging of the population and the increasing demand for rehabilitation robots, traditional serial robots have gradually failed to meet the needs. In order to solve this problem, domestic and foreign scholars and researchers have explored new lower limb rehabilitation robots based on parallel mechanisms in recent years. Compared with the six-degree-of-freedom parallel mechanism, the low-degree-of-freedom parallel mechanism has the advantages of low coupling and easy modularization, and is increasingly valued and favored by researchers. At the same time, some low-degree-of-freedom parallel mechanisms have been successfully applied in wrist rehabilitation robots, ankle rehabilitation robots, etc.

[0003] Existing parallel mechanisms for lower limb rehabilitation have published patents (such as CN104970945A, CN105943306A). There are too many ball hinges inside the mechanism, the structure is relatively complex, the processing and assembly accuracy is difficult to ensure, and the working space is limited. In addition, there is an inevitable gap between the ball head and the ball socket of the ball hinge due to the dynamic fit relationship. The process error and the friction during the hinge movement will aggravate the gap error and reduce the accuracy of the mechanism. Summary of the invention

[0004] In view of the problem that the existing parallel mechanism needs to use a ball hinge and has a complex structure, the present invention provides a three-degree-of-freedom parallel mechanism for lower limb rehabilitation, which has a simple structure, good rigidity and does not contain a ball hinge.

[0005] The technical solution is as follows: a three-degree-of-freedom parallel mechanism for lower limb rehabilitation, comprising a fixed base and a moving platform, wherein the fixed base is connected to the moving platform via a first branch chain, a second branch chain and a third branch chain, and characterized in that: the first branch chain comprises a first moving pair, a first rotating pair, a first connecting rod and a first universal joint connected in sequence, and the first universal joint comprises a rotating shaft 1 connected to the first connecting rod and a rotating shaft 2 connected to the moving platform;

[0006] The second branch chain includes a second moving pair, a second rotating pair, a second connecting rod and a second universal joint connected in sequence, and the second universal joint includes a rotating shaft 3 connected to the second connecting rod and a rotating shaft 4 connected to the moving platform;

[0007] The third branch chain includes a third moving pair, a third universal pair, a third connecting rod and a fourth universal pair connected in sequence, the third universal pair includes a rotating shaft 5 connected to the third moving pair, a rotating shaft 6 connected to one end of the third connecting rod, and the fourth universal pair includes a rotating shaft 7 connected to the other end of the third connecting rod and a rotating shaft 8 connected to the moving platform;

[0008] The first movable pair, the second movable pair and the third movable pair are respectively connected to the fixed base, the first universal joint, the second universal joint and the fourth universal joint are respectively connected to the moving platform, and the axes of the first movable pair, the second movable pair and the third movable pair are parallel to each other; the rotation axis of the first rotating pair is perpendicular to the axis of the first movable pair, the rotation axis of the first rotating pair is parallel to the axis of the rotating shaft one, the rotation axis of the second rotating pair is perpendicular to the axis of the second movable pair, the rotation axis of the second rotating pair is parallel to the axis of the rotating shaft three, the rotation axis of the first rotating pair is parallel to the rotation axis of the second rotating pair, the axis of the rotating shaft two is coaxial with the axis of the rotating shaft four, the axis of the rotating shaft five is parallel to the axis of the third movable pair, the axis of the rotating shaft six is ​​parallel to the axis of the rotating shaft seven, and when the moving platform is in a horizontal state, the axis of the rotating shaft eight is parallel to the axis of the rotating shaft one and the axis of the rotating shaft three, respectively.

[0009] It is further characterized by:

[0010] The first moving pair is arranged vertically;

[0011] The second moving pair is arranged vertically;

[0012] The third movable pair is arranged vertically;

[0013] The first moving pair comprises a first guide rail mounted on the fixed base and a first slider slidably matched with the first guide rail, and the first slider is driven to move on the first guide rail by a driving mechanism;

[0014] The second moving pair comprises a second guide rail mounted on the fixed base and a second slider slidably matched with the second guide rail, and the second slider is driven to move on the second guide rail by a driving mechanism;

[0015] The third moving pair comprises a third guide rail mounted on the fixed base and a third slider slidably matched with the third guide rail, and the third slider is driven to move on the third guide rail by a driving mechanism;

[0016] A foot fixing device is installed on the moving platform;

[0017] The first branch chain and the second branch chain are symmetrically distributed on both sides of the third branch chain;

[0018] The moving platform is square in shape, and the first branch chain and the second branch chain are respectively connected to two opposite sides of the moving platform.

[0019] The beneficial effects of the present invention are as follows: the parallel mechanism proposed in the present invention can realize two rotations and one movement in space, and the first branch chain and the second branch chain constituting the mechanism have the same structure, which is convenient for manufacturing and installation; the whole mechanism has the advantages of simple structure, high rigidity, good flexibility, easy control, etc., and the mechanism does not contain a ball hinge, is easy to manufacture and process, and has high precision. When in use, it can be connected in series with a linear single-axis drive to form a 2T2R hybrid lower limb rehabilitation robot to perform rehabilitation training for the lower limb hip joint, knee joint, and ankle joint. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the structure of the present invention;

[0021] Figure 2 Schematic diagram of the first branched chain structure;

[0022] Figure 3 is a schematic diagram of the second branched chain structure;

[0023] Figure 4 is a schematic diagram of the third branch chain structure;

[0024] Figure 5 is a schematic diagram of the first universal joint structure;

[0025] Figure 6 This is a schematic diagram of the split structure of the third universal joint;

[0026] Figure 7 This is a schematic diagram of the split structure of the fourth universal joint. DETAILED DESCRIPTION

[0027] like Figure 1 The three-degree-of-freedom parallel mechanism for lower limb rehabilitation shown in the figure includes a fixed base 1 and a moving platform 2. The moving platform 2 is square in shape. The first branch chain 4 and the second branch chain 5 are respectively connected to the two opposite sides of the moving platform 2. A plantar fixing device 21 is installed on the moving platform 2. The fixed base 1 is connected to the moving platform 2 through the first branch chain 3, the second branch chain 4 and the third branch chain 5, and the first branch chain 3 and the second branch chain 4 are symmetrically distributed on both sides of the third branch chain 5.

[0028] Specifically, Figure 2 As shown, the first branch chain 3 includes a first moving pair 31, a first rotating pair 32, a first connecting rod 33 and a first universal joint 34 connected in sequence. The first moving pair 31 is vertically arranged. The first moving pair 31 includes a first guide rail 311 installed on the fixed base 1 and a first slider 312 slidably matched with the first guide rail 311. The first slider 312 is driven by a driving mechanism 6, such as a driving motor, to move on the first guide rail 311. Figure 5 The first universal joint 34 includes a rotating shaft 341 connected to the first connecting rod 33 and a rotating shaft 342 connected to the moving platform 2. The first connecting rod 33 can rotate around the axis where the rotating shaft 341 is located, and the moving platform 2 can rotate around the axis where the rotating shaft 342 is located. More specifically, it also includes a U-shaped bracket 7 for installing the rotating shaft 341 and the rotating shaft 342. The rotating shaft 341 is fixed to the first connecting rod 33, and the rotating shaft 341 is rotatably connected to the U-shaped bracket 7 through a bearing, and the rotating shaft 2 is rotatably connected to the U-shaped bracket 7 through a bearing.

[0029] Similar to the first branch 3, Figure 3 As shown, the second branch chain 4 includes a second moving pair 41, a second rotating pair 42, a second connecting rod 43 and a second universal joint 44 connected in sequence. The second moving pair 41 is vertically arranged. The second moving pair 41 includes a second guide rail 411 installed on the fixed base 1 and a second slider 412 slidingly matched with the second guide rail 411. The second slider 412 is driven by the driving mechanism 6 to move on the second guide rail 411. Figure 5 The second universal joint 44 is similar to the first universal joint 34 and includes a rotating shaft 3 441 connected to the second connecting rod 43 and a rotating shaft 442 connected to the moving platform 2. The second connecting rod 43 can rotate around the axis where the rotating shaft 3 441 is located, and the moving platform 2 can rotate around the axis where the rotating shaft 442 is located.

[0030] like Figure 4 As shown, the third branch chain 5 includes a third moving pair 51, a third universal pair 52, a third connecting rod 53 and a fourth universal pair 54 connected in sequence. The third moving pair 51 is vertically arranged. The third moving pair 51 includes a third guide rail 511 installed on the fixed base 1 and a third slider 512 slidably matched with the third guide rail 511. The third slider 512 is driven by the driving mechanism 6 to move on the third guide rail 511. Figure 6The third universal joint 52 includes a rotating shaft 521 connected to the third moving joint 51 and a rotating shaft 6 522 connected to one end of the third connecting rod 53. A cross shaft can be used as the rotating shaft 521 and the rotating shaft 6 522. The third universal joint 52 can directly use a Hooke's joint. More specifically, the third slider 512 is connected to the rotating shaft 521 through a U-shaped bracket 28, the U-shaped bracket 28 and the rotating shaft 521 are connected through a bearing, and one end of the third connecting rod 53 is connected to the rotating shaft 6 522 through a U-shaped bracket 39, and they are also connected through a bearing. The structure of the fourth universal joint 54 can also be combined Figure 7 And referring to the structure of the first universal joint 34, it includes a rotating shaft 7 542 connected to the other end of the third connecting rod 53 and a rotating shaft 8 541 connected to the moving platform 2. The other end of the third connecting rod 53 can rotate around the axis where the rotating shaft 7 542 is located, and the moving platform 2 can rotate around the axis where the rotating shaft 8 541 is located.

[0031] The positional relationship between the above-mentioned moving pairs, rotating pairs and universal joints is as follows: the first moving pair 31, the second moving pair 41 and the third moving pair 51 are respectively connected to the fixed base 1, the first universal joint 34, the second universal joint 44 and the fourth universal joint 54 are respectively connected to the moving platform 2, and the axes of the first moving pair 31, the second moving pair 41 and the third moving pair 51 are parallel to each other; the rotation axis of the first rotating pair 32 is perpendicular to the axis of the first moving pair 31, the rotation axis of the first rotating pair 32 is parallel to the axis of the rotating shaft 341, and the rotation axis of the second rotating pair 42 is parallel to the axis of the rotating shaft 1. The axis is perpendicular to the axis of the second movable pair 41, the rotation axis of the second rotating pair 42 is parallel to the axis of the third rotating shaft 441, the rotation axis of the first rotating pair 32 is parallel to the rotation axis of the second rotating pair 42, the axis of the second rotating shaft 342 is coaxial with the axis of the fourth rotating shaft 442, the axis of the fifth rotating shaft 521 is parallel to the axis of the third movable pair 51, the axis of the sixth rotating shaft 522 is parallel to the axis of the seventh rotating shaft 542, and when the moving platform 2 is in a horizontal state, the axis of the eighth rotating shaft 541 is parallel to the axis of the first rotating shaft 341 and the axis of the third rotating shaft 441 respectively.

[0032] A three-degree-of-freedom 2PRU-PUU parallel mechanism is formed by the first branch chain 3 (PRU branch chain), the second branch chain 4 (PRU branch chain) and the third branch chain 5 (PUU branch chain) (wherein P represents a movable pair and is the active driving pair of the mechanism, R represents a rotating pair, and U represents a universal joint), which can realize the movement of the dynamic platform 2 with two rotations and one movement in space. Specifically, in combination with the plantar fixing device 21, when it is in a horizontal state, the axis from the toe to the heel is the X-axis, the vertical direction is the Z-axis, and the direction perpendicular to the X-axis and the Z-axis is the Y-axis. The mechanism can realize the rotation of the Y-axis, the rotation of the X-axis and the movement of the Z-axis; the set of mechanisms is connected in series with the linear single-axis driver 11 through the mounting seat 10 to form a 2T2R hybrid lower limb rehabilitation robot, which can realize the movement in the X-axis direction. After the user inserts the foot into the plantar fixing device 21, the rehabilitation training of the lower limb hip joint, knee joint and ankle joint can be performed through the movement of the mechanism.

[0033] The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by anyone familiar with the technology within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A three-degree-of-freedom parallel mechanism for lower limb rehabilitation, comprising a fixed base and a moving platform, wherein the fixed base is connected to the moving platform through a first branch chain, a second branch chain and a third branch chain, and characterized in that: The first branch chain includes a first moving pair, a first rotating pair, a first connecting rod and a first universal joint connected in sequence, and the first universal joint includes a first rotating shaft connected to the first connecting rod and a second rotating shaft connected to the moving platform; The second branch chain includes a second moving pair, a second rotating pair, a second connecting rod and a second universal joint connected in sequence, and the second universal joint includes a rotating shaft 3 connected to the second connecting rod and a rotating shaft 4 connected to the moving platform; The third branch chain includes a third moving pair, a third universal pair, a third connecting rod and a fourth universal pair connected in sequence, the third universal pair includes a rotating shaft 5 connected to the third moving pair, a rotating shaft 6 connected to one end of the third connecting rod, and the fourth universal pair includes a rotating shaft 7 connected to the other end of the third connecting rod and a rotating shaft 8 connected to the moving platform; The first movable pair, the second movable pair and the third movable pair are respectively connected to the fixed base, the first universal joint, the second universal joint and the fourth universal joint are respectively connected to the moving platform, and the axes of the first movable pair, the second movable pair and the third movable pair are parallel to each other; the rotation axis of the first rotating pair is perpendicular to the axis of the first movable pair, the rotation axis of the first rotating pair is parallel to the axis of the rotating shaft one, the rotation axis of the second rotating pair is perpendicular to the axis of the second movable pair, the rotation axis of the second rotating pair is parallel to the axis of the rotating shaft three, the rotation axis of the first rotating pair is parallel to the rotation axis of the second rotating pair, the axis of the rotating shaft two is coaxial with the axis of the rotating shaft four, the axis of the rotating shaft five is parallel to the axis of the third movable pair, the axis of the rotating shaft six is ​​parallel to the axis of the rotating shaft seven, and when the moving platform is in a horizontal state, the axis of the rotating shaft eight is parallel to the axis of the rotating shaft one and the axis of the rotating shaft three respectively; The moving platform is equipped with a foot fixing device; The moving platform is square in shape, and the first branch chain and the second branch chain are respectively connected to two opposite sides of the moving platform.

2. The three-degree-of-freedom parallel mechanism for lower limb rehabilitation according to claim 1, characterized in that: The first moving pair is arranged vertically.

3. The three-degree-of-freedom parallel mechanism for lower limb rehabilitation according to claim 1, characterized in that: The second moving pair is arranged vertically.

4. The three-degree-of-freedom parallel mechanism for lower limb rehabilitation according to claim 1, characterized in that: The third moving pair is arranged vertically.

5. The three-degree-of-freedom parallel mechanism for lower limb rehabilitation according to claim 1 or 2, characterized in that: The first moving pair includes a first guide rail installed on the fixed base and a first slider slidably matched with the first guide rail. The first slider is driven to move on the first guide rail by a driving mechanism.

6. The three-degree-of-freedom parallel mechanism for lower limb rehabilitation according to claim 1 or 3, characterized in that: The second moving pair includes a second guide rail mounted on the fixed base and a second slider slidably matched with the second guide rail, and the second slider is driven to move on the second guide rail by a driving mechanism.

7. The three-degree-of-freedom parallel mechanism for lower limb rehabilitation according to claim 1 or 4, characterized in that: The third moving pair includes a third guide rail installed on the fixed base and a third slider slidably matched with the third guide rail. The third slider is driven to move on the third guide rail by a driving mechanism.

8. The three-degree-of-freedom parallel mechanism for lower limb rehabilitation according to any one of claims 1 to 4, characterized in that: The first branch chain and the second branch chain are symmetrically distributed on both sides of the third branch chain.

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