A three-branch two-rotation parallel robot mechanism for ankle joint rehabilitation

Abstract

The present invention discloses a three-branch two-rotation ankle joint rehabilitation parallel robot mechanism, comprising a moving platform, a fixed platform, two active branches and a just-constrained branch. The two active branches have the same kinematic chain structure, and are respectively composed of a parallelogram structure, a revolute pair and a universal joint. The parallelogram structure comprises two revolute pairs with parallel axes and two universal joints. The just-constrained branch is composed of two revolute pairs with perpendicular axes connected in series. One end of the third universal joint of the first active branch is connected to the just-constrained branch, and one end of the sixth universal joint of the second active branch is connected to the moving platform. The velocity Jacobian matrix of the parallel robot mechanism of the present invention is a diagonal matrix, which realizes a one-to-one control relationship between the input motion and the output motion of the mechanism.

Description

Technical Field

[0001] The invention relates to the field of rehabilitation robot space mechanism, in particular to a three-branch two-rotation ankle joint rehabilitation parallel robot mechanism. Background Art

[0002] Ankle sprain is a common sports injury in orthopedic clinics. The ankle is an important hub and load-bearing joint for human movement. If this happens, if effective treatment and rehabilitation training are not received in time, it is easy to cause joint instability and repeated ankle injuries. In severe cases, the patient will permanently lose the ability to walk normally. Rehabilitation training for the ankle is essential. The research on ankle rehabilitation robots began in the 1990s. In the field of hemiplegia rehabilitation, traditional physical therapists will be replaced by ankle rehabilitation robots. Research on ankle rehabilitation robot mechanisms has become a trend.

[0003] Due to the long transmission chain, many rods and inconvenient control of the series mechanism, parallel mechanisms are often used for ankle rehabilitation training. For example, Chinese patent application number CN201610028816.4 discloses an ankle rehabilitation parallel mechanism with an active branch chain tilted arrangement; Chinese patent application number CN201710962288.4 discloses a three-degree-of-freedom parallel mechanism ankle rehabilitation device. However, the research on general parallel mechanisms still has problems such as strong coupling and complex kinematic and dynamic problem solving. Summary of the invention

[0004] In order to address the deficiencies in the prior art, the present invention proposes a three-branch, two-rotation parallel robot mechanism for ankle joint rehabilitation. The parallel robot mechanism has uncoupled kinematic characteristics and a very simple control design. At the same time, the just-constrained branch chain can not only enhance the overall stability and load-bearing capacity of the parallel mechanism, but also improve the accuracy and uncontrollable errors of the parallel mechanism.

[0005] In order to achieve the above object, the specific scheme adopted by the present invention is:

[0006] A three-branch two-rotation ankle joint rehabilitation parallel robot mechanism, comprising a fixed platform, a moving platform, a just-constrained branch chain that only provides constraints, and two active branch chains that provide driving force;

[0007] The constrained branch chain includes a first rotating pair and a second rotating pair whose axes are perpendicular to each other and a constrained connecting rod for connecting the first rotating pair and the second rotating pair, wherein the first rotating pair is connected to the fixed platform and the second rotating pair is connected to the moving platform;

[0008] The two active branch chains include a first active branch chain for controlling the moving platform to rotate around the first rotation pair and a second active branch chain for controlling the moving platform to rotate around the second rotation pair;

[0009] The first active branch chain includes a first parallelogram structure, a third connecting rod, a fifth rotating pair, a fourth connecting rod and a third universal joint which are connected in series in sequence from the fixed platform, the fourth connecting rod is connected to the third connecting rod and the constraint connecting rod through the fifth rotating pair and the third universal joint respectively, the second axis of the third universal joint is parallel to the axis of the first rotating pair, and the rotating axis of the fifth rotating pair is perpendicular to the axis of the first rotating pair;

[0010] The second active branch chain includes a second parallelogram structure, a seventh connecting rod, an eighth rotating pair, an eighth connecting rod and a sixth universal joint which are connected in series in sequence from the fixed platform, the eighth connecting rod is connected to the seventh connecting rod and the moving platform through the eighth rotating pair and the sixth universal joint respectively, the rotation axis of the eighth rotating pair is parallel to the first axis of the sixth universal joint and is perpendicular to the rotation axis of the fifth rotating pair;

[0011] The first parallelogram structure and the second parallelogram structure both include two revolute pairs with parallel axes and two universal joints, and any revolute pair in each parallelogram structure can be selected as an active pair.

[0012] Furthermore, the first parallelogram structure is composed of a third rotating pair, a fourth rotating pair, a first universal joint, a second universal joint, a first connecting rod and a second connecting rod. The first connecting rod is connected to the fixed platform and the third connecting rod through the fourth rotating pair and the first universal joint respectively, and the second connecting rod is connected to the fixed platform and the third connecting rod through the third rotating pair and the second universal joint respectively. The rotation axes of the third rotating pair and the fourth rotating pair are parallel to the first axis of the second universal joint and the second axis of the third universal joint.

[0013] Furthermore, the second parallelogram structure is composed of the sixth rotation pair, the seventh rotation pair, the fourth universal joint, the fifth universal joint, the fifth connecting rod and the sixth connecting rod. The fifth connecting rod is connected to the fixed platform and the seventh connecting rod through the seventh rotation pair and the fourth universal joint respectively. The sixth connecting rod is connected to the fixed platform and the seventh connecting rod through the sixth rotation pair and the fifth universal joint respectively. The rotation axes of the sixth rotation pair and the seventh rotation pair are both perpendicular to the second axis of the fourth universal joint and the second axis of the third universal joint.

[0014] Furthermore, the cross section of the moving platform is rectangular.

[0015] Beneficial effects:

[0016] 1. The parallel robot mechanism of the present invention includes a fixed platform, a moving platform, a just-constrained branch chain and two active branch chains (a first active branch chain and a second active branch chain). The just-constrained branch chain includes a first rotating pair and a second rotating pair with two axes perpendicular to each other. The two active branch chains both include a parallelogram structure, a rotating pair and a universal joint connected in series in sequence starting from the fixed platform. Each parallelogram structure includes a rotating pair with two axes parallel and two universal joints. The first active branch chain can control the moving platform to rotate around the first rotating pair, and the second active branch chain can control the moving platform to rotate around the second rotating pair. The parallel robot mechanism has uncoupled kinematic characteristics and the control design is also very simple. At the same time, the just-constrained branch chain can not only enhance the overall stability and carrying capacity of the parallel mechanism, but also improve the accuracy and uncontrollable errors of the parallel mechanism.

[0017] 2. The parallel mechanism in the present invention has a simple structure, high flexibility, simple control, strong practicality, and good promotion and utilization value.

[0018] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 It is a structural schematic diagram of the parallel robot mechanism in the present invention.

[0021] Graphic markings: P1, fixed platform, P2, moving platform;

[0022] L1, first active branch chain, 10, third rotation pair, 11, fourth rotation pair, 12, first connecting rod, 13, second connecting rod, 14, first universal joint, 141, first axis of first universal joint, 142, second axis of first universal joint, 15, second universal joint, 151, first axis of second universal joint, 152, second axis of second universal joint, 16, third connecting rod, 17, fifth rotation pair, 18, fourth connecting rod, 19, third universal joint, 191, first axis of third universal joint, 192, second axis of third universal joint;

[0023] L2, second active branch chain, 20, sixth rotation pair, 21, seventh rotation pair, 22, fifth connecting rod, 23, sixth connecting rod, 24, fourth universal joint, 241, first axis of fourth universal joint, 242, second axis of fourth universal joint, 25, fifth universal joint, 251, first axis of fifth universal joint, 252, second axis of fifth universal joint, 26, seventh connecting rod, 27, eighth rotation pair, 28, eighth connecting rod, 29, sixth universal joint, 291, first axis of sixth universal joint, 292, second axis of sixth universal joint;

[0024] L3, just constrained branch chain, 30, first rotation pair, 31, constrained connecting rod, 32, second rotation pair. DETAILED DESCRIPTION

[0025] The technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0026] The “first” and “second” mentioned in the present invention are not limitations on the quantity of the corresponding technical features, but are names given to distinguish the relevant technical features.

[0027] A three-branch two-rotation ankle joint rehabilitation parallel robot mechanism, please refer to Figure 1 , the parallel robot mechanism comprises:

[0028] Set platform P1;

[0029] The moving platform P2 is arranged above the fixed platform P1 and has a rectangular cross section.

[0030] A just-constrained branch chain L3: the just-constrained branch chain L3 is connected between the fixed platform P1 and the movable platform P2, and comprises a first rotational pair 30 and a second rotational pair 32 whose axes are perpendicular to each other, and a constraint link 31 for connecting the first rotational pair 30 and the second rotational pair 32, wherein the first rotational pair 30 is connected to the fixed platform P1, and the second rotational pair 32 is connected to the movable platform P2;

[0031] There are two active branch chains, each of which includes a parallelogram structure, a rotating pair and a universal joint in sequence. The two ends of the first active branch chain L1 of the two active branch chains are respectively hinged to the fixed platform P1 and the constraint link 31, and the two ends of the second active branch chain L2 are respectively hinged to the fixed platform P1 and the moving platform P2; the first active branch chain L1 can control the moving platform P2 to rotate around the axis of the first rotating pair 30, and the second active branch chain L2 can control the moving platform P2 to rotate around the axis of the second rotating pair 32.

[0032] In detail, the first active branch chain L1 includes a first parallelogram structure, a third link 16, a fifth rotating pair 17, a fourth link 18 and a third universal joint 19 which are connected in series from the fixed platform P1. The fourth link 18 is connected to the third link 16 and the constraint link 31 through the fifth rotating pair 17 and the third universal joint 19 respectively. The second axis 192 of the third universal joint is parallel to the axis of the first rotating pair 30, and the rotation axis of the fifth rotating pair 17 is perpendicular to the axis of the first rotating pair 30.

[0033] The first parallelogram structure is composed of a third rotating pair 10, a fourth rotating pair 11, a first universal joint 14, a second universal joint 15, a first connecting rod 12 and a second connecting rod 13. The first connecting rod 12 is connected to the fixed platform P1 and the third connecting rod 16 through the fourth rotating pair 11 and the first universal joint 14 respectively. The second connecting rod 13 is connected to the fixed platform P1 and the third connecting rod 16 through the third rotating pair 10 and the second universal joint 15 respectively. The rotation axes of the third rotating pair 10 and the fourth rotating pair 11 are parallel to the first axis 151 of the second universal joint and the second axis 192 of the third universal joint.

[0034] The second active branch chain l2 includes a second parallelogram structure, a seventh connecting rod 26, an eighth rotating pair 27, an eighth connecting rod 28 and a sixth universal joint 29 which are connected in series from the fixed platform P1. The eighth connecting rod 28 is connected to the seventh connecting rod 26 and the moving platform P2 through the eighth rotating pair 27 and the sixth universal joint 29 respectively. The rotation axis of the eighth rotating pair 27 is parallel to the first axis 291 of the sixth universal joint and perpendicular to the rotation axis of the fifth rotating pair 17.

[0035] The second parallelogram structure is composed of the sixth rotating pair 20, the seventh rotating pair 21, the fourth universal joint 24, the fifth universal joint 25, the fifth connecting rod 22 and the sixth connecting rod 23. The fifth connecting rod 22 is connected to the fixed platform P1 and the seventh connecting rod 26 through the seventh rotating pair 21 and the fourth universal joint 24, respectively. The sixth connecting rod 23 is connected to the fixed platform P1 and the seventh connecting rod 26 through the sixth rotating pair 20 and the fifth universal joint 25, respectively. The rotation axes of the sixth rotating pair 20 and the seventh rotating pair 21 are both perpendicular to the second axis 242 of the fourth universal joint and the second axis 192 of the third universal joint.

[0036] The third rotational pair 10 or the fourth rotational pair 11 of the first parallelogram structure and the sixth rotational pair 20 or the seventh rotational pair 21 of the second parallelogram structure can be selected as active pairs.

[0037] When the parallel robot mechanism of the present invention is in use, the active pair (the third rotation pair 10 or the fourth rotation pair 11) in the first active branch chain L1 is driven by a motor, thereby controlling the movable platform P2 to rotate around the axis of the first rotation pair 30 in the just constraint branch chain L3, and the active pair (the sixth rotation pair 20 or the seventh rotation pair 21) in the second active branch chain is driven by a motor, thereby controlling the movable platform P2 to rotate around the axis of the second rotation pair 32 in the just constraint branch chain L3. The patient's feet are placed on the front of the movable platform P2, thereby achieving ankle joint rehabilitation training.

[0038] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any equivalent changes or modifications made according to the essence of the present invention should be included in the protection scope of the present invention.

Claims

1. A three-branch two-rotation ankle joint rehabilitation parallel robot mechanism, characterized in that: It includes a fixed platform (P1), a moving platform (P2), a just-constrained branch chain (L3) that only provides constraints, and two active branches that provide driving force; The constrained branch chain (L3) comprises a first rotating pair (30) and a second rotating pair (32) whose axes are perpendicular to each other, and a constrained connecting rod (31) used to connect the first rotating pair (30) and the second rotating pair (32), wherein the first rotating pair (30) is connected to the fixed platform (P1), and the second rotating pair (32) is connected to the moving platform (P2); The two active branch chains include a first active branch chain (L1) for controlling the rotation of the moving platform (P2) around a first rotation pair (30) and a second active branch chain (L2) for controlling the rotation of the moving platform (P2) around a second rotation pair (32); The first active branch chain (L1) comprises a first parallelogram structure, a third connecting rod (16), a fifth rotating pair (17), a fourth connecting rod (18) and a third universal joint (19) which are sequentially connected in series starting from the fixed platform (P1); the fourth connecting rod (18) is connected to the third connecting rod (16) and the constraint connecting rod (31) via the fifth rotating pair (17) and the third universal joint (19), respectively; the second axis (192) of the third universal joint is parallel to the axis of the first rotating pair (30); and the rotating axis of the fifth rotating pair (17) is perpendicular to the axis of the first rotating pair (30); The second active branch chain (l2) comprises a second parallelogram structure, a seventh connecting rod (26), an eighth rotating pair (27), an eighth connecting rod (28) and a sixth universal joint (29) which are sequentially connected in series from the fixed platform (P1); the eighth connecting rod (28) is connected to the seventh connecting rod (26) and the moving platform (P2) via the eighth rotating pair (27) and the sixth universal joint (29) respectively; the rotation axis of the eighth rotating pair (27) is parallel to the first axis (291) of the sixth universal joint and is perpendicular to the rotation axis of the fifth rotating pair (17); The first parallelogram structure and the second parallelogram structure both include two revolute pairs with parallel axes and two universal joints, and any revolute pair in each parallelogram structure can be selected as an active pair; The first parallelogram structure is composed of a third rotating pair (10), a fourth rotating pair (11), a first universal joint (14), a second universal joint (15), a first connecting rod (12) and a second connecting rod (13); the first connecting rod (12) is connected to the fixed platform (P1) and the third connecting rod (16) through the fourth rotating pair (11) and the first universal joint (14), respectively; the second connecting rod (13) is connected to the fixed platform (P1) and the third connecting rod (16) through the third rotating pair (10) and the second universal joint (15), respectively; the rotating axes of the third rotating pair (10) and the fourth rotating pair (11) are parallel to the first axis (151) of the second universal joint and the second axis (192) of the third universal joint; The second parallelogram structure is composed of a sixth rotating pair (20), a seventh rotating pair (21), a fourth universal joint (24), a fifth universal joint (25), a fifth connecting rod (22) and a sixth connecting rod (23); the fifth connecting rod (22) is connected to the fixed platform (P1) and the seventh connecting rod (26) via the seventh rotating pair (21) and the fourth universal joint (24), respectively; the sixth connecting rod (23) is connected to the fixed platform (P1) and the seventh connecting rod (26) via the sixth rotating pair (20) and the fifth universal joint (25), respectively; the rotating axes of the sixth rotating pair (20) and the seventh rotating pair (21) are both perpendicular to the second axis (242) of the fourth universal joint and the second axis (192) of the third universal joint.

2. The three-branch two-rotation ankle joint rehabilitation parallel robot mechanism according to claim 1, characterized in that: The cross section of the moving platform (P2) is rectangular.

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