A spatial rhombic remote center of motion mechanism

Abstract

The application discloses a kind of space rhombus remote center of motion mechanism, belong to medical operation robot technical field.The mechanism includes first space one rotation two movement closed-loop branch, second space one rotation two movement closed-loop branch and third space rhombus closed-loop chain;Wherein first, second space one rotation two movement closed-loop branch is respectively by fixed base, dynamic platform and the branch chain connecting both, and third space rhombus closed-loop chain connects two dynamic platforms and contains rhombus branch chain and fifth branch chain.The mechanism uses moving pair and rotary pair as driving pair, can realize two rotary motions and one movement motion around remote center of motion point.The application structure is simple, rigid, high precision, and the spatial position of remote center of motion point can be adjusted by changing dynamic platform size parameter, is suitable for minimally invasive surgery robot and other medical scenarios.

Description

Technical Field

[0001] This invention belongs to the field of medical surgical robot technology, specifically relating to a spatial rhomboid remote motion center mechanism that enables a hand robot to perform two rotations and one movement about the puncture point during puncture surgery, and whose RCM point position can be changed by modifying dimensional parameters. Background Technology

[0002] The core feature of a Remote Center of Motion (RCM) is its ability to perform remote spatial tasks, allowing for continuous rotational movements around a fixed point in space. It is currently widely used in minimally invasive and assisted surgical procedures. Furthermore, the movement patterns of RCM devices are consistent with human joint movements, thus making them practically valuable in rehabilitation institutions for wrist and knee joints.

[0003] Existing research shows that the main structural forms for achieving remote center motion (RCM) include: telecentric motion achieved through control algorithms, arc-shaped guide rail mechanisms, parallelogram linkage mechanisms, synchronous belt mechanisms, spherical linkage mechanisms, universal joint mechanisms, parallel wrist joint mechanisms, and planetary gear trains. Among these, parallelogram linkage mechanisms (such as CN 113116404 A) can only achieve planar tasks, and interference between links is prone to occur; RCM mechanisms using synchronous belts (such as CN 109394342 B) have poor rigidity, low load capacity, and require frequent maintenance; mechanisms that achieve RCM motion through control algorithms have no fixed constraints on the RCM point, and control failure may lead to incision pulling risks, making them unreliable during surgery; the RCM point positions of arc-shaped guide rail (such as CN 108670411 B) and spherical linkage (such as CN 108972507 A) RCM mechanisms are determined by multiple branches, requiring high assembly precision.

[0004] The RCM mechanisms widely used in minimally invasive surgical robot systems are mainly divided into two categories: parallelogram RCM mechanisms and parallel RCM mechanisms. Parallelogram RCM mechanisms are characterized by their simple structure and large workspace. However, planar four-bar mechanisms can only satisfy rotation within a plane. To achieve spatial motion, additional revolute or prismatic joints must be connected in series (such as CN114504427 A, CN 115990061 A, CN 109602498 A). This leads to error accumulation, reducing the accuracy of the RCM point position and hindering surgical applications. Parallel RCM mechanisms (such as CN115476339 A) possess good rigidity, but their overall structure is complex, requiring high assembly standards, making direct application in the surgical field difficult. Furthermore, the RCM mechanism of the transmission has a fixed RCM point position, which cannot be changed or can only be changed in one direction, resulting in relatively poor flexibility (e.g., CN 106037936 B, CN 113664809 B, CN 101497198 A).

[0005] Therefore, it is hoped that by combining the advantages of planar quadrilateral RCM mechanisms and parallel RCM mechanisms, a novel spatial RCM mechanism with good rigidity, high precision, and the ability to change the position of RCM points in space can be proposed to improve the adaptability of robots in minimally invasive surgery. Summary of the Invention

[0006] This invention overcomes the shortcomings of the above-mentioned background technology and proposes a novel remote motion center mechanism that combines linear drive and rotation drive, has a simple structure, a large working space, excellent performance, adjustable spatial RCM point position, and simple control, so as to meet the needs of positioning different positions and performing puncture movements during surgery.

[0007] The technical solution provided by this invention is:

[0008] A spatial rhombic RCM mechanism includes a first spatial one-turn two-shift closed-loop branch, a second spatial one-turn two-shift closed-loop branch, and a third spatial rhombic closed-loop chain. The first spatial one-turn two-shift closed-loop branch includes a fixed base, a first moving platform, and a first branch and a second branch connecting the moving platform and the fixed base. The second spatial one-turn two-shift closed-loop branch includes a fixed base, a second moving platform, and a third branch and a fourth branch connecting the moving platform and the fixed base. The third spatial rhombic closed-loop chain includes a rhombic branch and a fifth branch connected to the first moving platform and the second moving platform.

[0009] The first branch includes a first universal joint, a first sliding joint, and a second universal joint connected between the fixed base and the first moving platform; the second branch includes a third universal joint and a first revolute joint connected between the fixed base and the first moving platform; in the first branch, the first rotation axis of the first universal joint connecting the fixed base and the first sliding joint is located on the fixed base, the second rotation axis is perpendicular to the axis of the first sliding joint, the first rotation axis of the first universal joint is parallel to the second rotation axis of the second universal joint, and the second rotation axis of the first universal joint is parallel to the first rotation axis of the second universal joint; in the second branch, the first rotation axis of the third universal joint is located on the fixed base, and the rotation axis of the first revolute joint is parallel to the second rotation axis of the third universal joint.

[0010] The third branch includes a fourth universal joint, a second sliding joint, and a fifth universal joint connected between the fixed base and the second moving platform; the fourth branch includes a sixth universal joint and a second revolute joint connected between the fixed base and the second moving platform; in the third branch, the first rotation axis of the fourth universal joint connecting the fixed base and the second sliding joint is located on the fixed base, the second rotation axis is perpendicular to the axis of the second sliding joint, the first rotation axis of the fourth universal joint is parallel to the second rotation axis of the fifth universal joint, and the second rotation axis of the fourth universal joint is parallel to the first rotation axis of the fifth universal joint; in the fourth branch, the first rotation axis of the sixth universal joint is located on the fixed base, and the rotation axis of the first revolute joint is parallel to the second rotation axis of the sixth universal joint.

[0011] The rhomboid branch includes a third and a fourth revolute joint connected to the first and second moving platforms, a fifth revolute joint connected to the third sliding joint, and a sixth and a seventh revolute joint connected to the rhomboid member; the fifth branch includes an eighth transfer joint connected to the rhomboid member and a fifth transfer joint connected to the third sliding joint; the third revolute joint and the first revolute joint are on the same member, the fourth revolute joint and the second revolute joint are on the same member, the fifth revolute joint is connected to the third sliding joint, and the sixth and seventh revolute joints, together with the fifth and eighth transfer joints, form a rhomboid closed loop.

[0012] Of the six branches, the first and third branches are symmetrically distributed relative to the intermediate plane determined by the RCM point in the initial state; the first rotation axis of the first universal joint in the first branch, the first rotation axis of the third universal joint in the second branch, the first rotation axis of the fourth universal joint in the third branch, and the first rotation axis of the sixth universal joint in the fourth branch always remain parallel; the intersection of the axis of the link connecting the fifth and eighth rotating joints in the fifth branch with the first rotation axis of the third universal joint is the RCM point of the mechanism.

[0013] The prismatic joints in the first and third branches are driving joints, and the revolute joints in the second and fourth branches are driving joints. When the driving joints move according to a certain pattern, the mechanism can realize two rotational movements around the RCM point and one prismatic movement along the RCM point.

[0014] Compared with the prior art, the beneficial effects of the present invention are: the novel 2R1T spatial rhombic RCM parallel mechanism proposed in the present invention effectively avoids the disadvantages of planar RCM mechanisms, such as multiple serial modules, large moving mass, and traditional parallel RCM mechanisms, such as small working space and difficulty in arrangement. At the same time, the position of the RCM point in space can be changed by changing the configuration of the mechanism links, which has good prospects for applications such as minimally invasive surgery. Attached Figure Description

[0015] Figure 1 This is a three-dimensional structural schematic diagram of Embodiment 1 of the present invention;

[0016] Figure 2 This is a schematic diagram of the first branch structure;

[0017] Figure 3 This is a schematic diagram of the second branch structure;

[0018] Figure 4 This is a schematic diagram of the fourth branch structure;

[0019] Figure 5 A diagram illustrating the change in the RCM point position.

[0020] Figure 6 This is a schematic diagram of the overall structure of the present invention. Detailed Implementation

[0021] The present invention will be further described below with reference to the embodiments:

[0022] This invention belongs to the field of medical surgical robot technology. The purpose is to propose a novel spatial rhomboid mechanism that is simple in structure, easy to install, and has an adjustable Remote Center-of-Motion (RCM) point position.

[0023] A spatial three-degree-of-freedom multi-loop parallel mechanism includes a first spatial one-rotation-two-transfer closed-loop branch, a second spatial one-rotation-two-transfer closed-loop branch, and a third spatial rhombic closed-loop chain. The first spatial one-rotation-two-transfer closed-loop branch includes a fixed base, a first moving platform, and a first branch and a second branch connecting the moving platform and the fixed base. The first branch includes a universal joint, a sliding joint, and a universal joint connected to the fixed base. The second branch includes a universal joint and a revolute joint connecting the fixed base and the moving platform. The second spatial one-rotation-two-transfer closed-loop branch includes a fixed base... The system comprises a base, a second moving platform, and a third and fourth branch connecting the moving platform and the fixed base. The third branch includes a universal joint, a sliding joint, and another universal joint connected to the fixed base. The fourth branch includes a universal joint and a revolute joint connecting the fixed base and the moving platform. The third spatial rhombic closed-loop chain includes a rhombic branch and a fifth branch connected to the first and second moving platforms. The rhombic branch includes a revolute joint connecting the moving platform and the fifth branch. The fifth branch includes a revolute joint connected to the end member and a revolute joint connected to the rhombic branch. The mechanism has three degrees of freedom in space, with sliding joints in the first and third branches and revolute joints in the second and fourth branches. The RCM point is the intersection of the first rotation axis of the universal joint of the second branch and the connecting rod of the fifth branch. It can realize two rotational movements around the RCM point and one slidable movement along the RCM point. Modifying the parameters of the moving platform can change the position of the RCM point in space. This mechanism includes both a spatial parallel closed-loop unit and a rhomboid connected closed-loop unit. It can achieve spatial two-rotation and one-transfer RCM motion while possessing the advantages of both parallel and RCM mechanisms. Furthermore, the spatial position of the RCM point can be adjusted by adjusting the parameters of the rods, making it a promising candidate for application in the field of minimally invasive surgery.

[0024] Figure 1 The novel 2R1T spatial RCM parallel mechanism shown has a specific configuration of 2UPU&UR-3R-RRP (where P represents a prismatic joint and is the active driving joint of the mechanism, U represents a universal joint, and R represents a revolute joint). This mechanism includes: a fixed base 12, a first moving platform 6, a second moving platform 5, an end platform 11, rhomboid branches 7, 8, 9, and 10, a first branch 1, a second branch 2, a third branch 3, and a fourth branch 4. Specifically: the fixed base 12, the first branch 1, the second branch 2, and the first moving platform 6 form a first spatial one-turn two-shift closed chain; the fixed base 12, the third branch 3, the fourth branch 4, and the second moving platform 5 form a second spatial one-turn two-shift closed chain; and the rhomboid branches 7, 8, 9, and 10, and the end platform 11 form a third spatial rhomboid closed-loop chain. The driving pairs of the mechanism are the prismatic pairs of the first branch 1 and the third branch 3, and the revolute pairs of the second branch 2 and the fourth branch 4. When the prismatic pairs move, the required three-degree-of-freedom spatial RCM motion can be realized, namely: two rotational motions about the RCM point and a feed motion through the axis of the end member of the RCM point.

[0025] like Figure 1 , Figure 2 , Figure 3 As shown, the first and second branches are structurally identical and symmetrically distributed with the third and fourth branches, including the first universal joint 13 and the fourth universal joint 21, the second universal joint 16 and the fifth universal joint 24, the third universal joint 20 and the sixth universal joint 28, the first prismatic joint 14 and the second prismatic joint 22, the first link 15 and the third link, the second link 19 and the fourth link 27, and the first moving platform 17 and the second moving platform 25, all with the same structure.

[0026] In the first branch 1, the first universal joint 13 connects the fixed base 12 and the first sliding joint 14. The first sliding joint 14 connects the first universal joint 13 and the first connecting rod 15. The first connecting rod 15 connects the first sliding joint 14 and the second universal joint 16. The second universal joint 16 connects the first connecting rod 14 and the first moving platform 17. This branch is called the UPU branch. The second rotation axis 112 of the first universal joint 13 is always perpendicular to the axis of the first sliding joint 14. The first rotation axis 111 of the first universal joint 13 is always parallel to the second rotation axis 122 of the second universal joint 16. The second rotation axis 112 of the first universal joint 13 is always parallel to the first rotation axis 121 of the second universal joint 16.

[0027] In the second branch 2, the third universal joint 20 connects the fixed base 12 and the second rod 19, the second rod 19 connects the third universal joint 20 and the first rotating joint 18, and the first rotating joint 18 connects the second rod 19 and the first moving platform 17. This branch is called the UR branch. The second rotation axis 212 of the third universal joint 20 is always perpendicular to the axis of the second rod 19, the first rotation axis 211 of the third universal joint 20 is always parallel to the first rotation axis 111 of the first universal joint 13, and the second rotation axis 212 of the third universal joint 20 is always parallel to the axis of the first rotating joint 18.

[0028] In the third branch 3, the fourth universal joint 21 connects the fixed base 12 and the second sliding joint 22. The second sliding joint 22 connects the fourth universal joint 21 and the third link 23. The third link 23 connects the second sliding joint 22 and the fifth universal joint 24. The fifth universal joint 24 connects the third link 23 and the second moving platform 25. This branch is called the UPU branch. The second rotation axis 312 of the fourth universal joint 21 is always perpendicular to the axis of the second sliding joint 22. The first rotation axis 311 of the fourth universal joint 21 is always parallel to the second rotation axis 322 of the fifth universal joint 24. The second rotation axis 312 of the fourth universal joint 21 is always parallel to the first rotation axis 321 of the fifth universal joint 24.

[0029] In the fourth branch 4, the sixth universal joint 28 connects the fixed base 12 and the fourth member 27, the fourth member 27 connects the sixth universal joint 28 and the second rotating joint 26, and the second rotating joint 26 connects the fourth member 27 and the second moving platform 25. This branch is called the UR branch. The second rotation axis 412 of the sixth universal joint 28 is always perpendicular to the axis of the fourth member 27, the first rotation axis 411 of the sixth universal joint 28 is always parallel to the first rotation axis 311 of the fourth universal joint 21, and the second rotation axis 412 of the sixth universal joint 28 is always parallel to the axis of the second rotating joint 26.

[0030] like Figure 1 , Figure 4 As shown, in the rhomboid branches 7, 8, 9, and 10, the third revolute joint 29 connects the second moving platform 25 and the fifth link 30; the fifth link 30 connects the third revolute joint 29 and the sixth revolute joint 36; the sixth revolute joint 36 connects the sixth link 37 and the eighth revolute joint 38; the fourth revolute joint 31 connects the first moving platform 17 and the seventh link 32; the seventh link 32 connects the fourth revolute joint 31 and the seventh revolute joint 34; the seventh revolute joint 34 connects the eighth link 35 and the eighth revolute joint 38; the eighth revolute joint 38 connects the ninth link 40 and the fifth revolute joint 33; and the fifth revolute joint 33 connects the third prismatic joint 39 and the ninth link 40. This branch is collectively referred to as the rhomboid 3R-3R branch. The rotation axes of this branch are always parallel to the second rotation axis 112 of the first universal joint.

[0031] The first rotation axis 111 of the first universal joint remains parallel to the first rotation axis 211 of the third universal joint, the first rotation axis 311 of the fourth universal joint, and the first rotation axis 411 of the sixth universal joint. The rotation axis of the first revolute joint 18 remains parallel to the rotation axis of the second revolute joint 26. The distance between the axes of the first revolute joint 18 and the fourth revolute joint 31 is equal to the distance between the axes of the second revolute joint 26 and the fourth transfer joint 29. The intersection point O of the line connecting the first rotation axis 211 of the third universal joint 20 and the centers of the fifth and eighth revolute joints is the RCM point. When the sliding joints in branches one and three are driven by the lead screw mechanism, and the revolute joints in branches two and four are driven by the motor, the mechanism can realize two rotational movements around the RCM point and one translational movement along the RCM point. By changing the dimensional parameters of the moving platform, the position of the RCM point in space can be changed.

[0032] The beneficial effects of this invention are: the novel 2R1T spatial rhombic RCM parallel mechanism proposed in this invention effectively avoids the disadvantages of planar RCM mechanisms, such as multiple serial modules, large moving mass, and traditional parallel RCM mechanisms, such as small working space and difficulty in arrangement. At the same time, the position of the RCM point in space can be changed by changing the configuration of the mechanism links, which has good prospects for applications such as minimally invasive surgery.

Claims

1. A spatial rhomboid remote motion center mechanism, characterized in that, include: The first spatial one-turn two-shift closed-loop branch includes a fixed base (12), a first moving platform (17), and a first branch (1) and a second branch (2) connecting the fixed base (12) and the first moving platform (17). The second space one-turn two-shift closed-loop branch includes a fixed base (12), a second moving platform (5), and a third branch (3) and a fourth branch (4) connecting the fixed base (12) and the second moving platform (5). The third space diamond closed loop chain includes diamond branches (7, 8, 9, 10) and a fifth branch (11) connected to the first moving platform (17) and the second moving platform (5).

2. The spatial rhomboid remote motion center mechanism according to claim 1, characterized in that, The first branch (1) includes a first universal joint (13), a first sliding joint (14) and a second universal joint (16) connected between the fixed base (12) and the first moving platform (17). The second branch (2) includes a third universal joint (20) and a first rotary joint (18) connected between the fixed base (12) and the first moving platform (17); In the first branch (1), the first rotation axis (111) of the first universal joint (13) is located on the fixed base (12), the second rotation axis (112) is perpendicular to the axis of the first sliding joint (14), the first rotation axis (111) of the first universal joint (13) is parallel to the second rotation axis (122) of the second universal joint (16), and the second rotation axis (112) of the first universal joint (13) is parallel to the first rotation axis (121) of the second universal joint (16). In the second branch (2), the first rotation axis (211) of the third universal joint (20) is located on the fixed base (12), and the rotation axis of the first rotating joint (18) is parallel to the second rotation axis (212) of the third universal joint (20).

3. The spatial rhomboid remote motion center mechanism according to claim 1, characterized in that, The third branch (3) includes a fourth universal joint (21), a second sliding joint (22) and a fifth universal joint (24) connected between the fixed base (12) and the second moving platform (5). The fourth branch (4) includes a sixth universal joint (28) and a second rotary joint (26) connected between the fixed base (12) and the second moving platform (5). In the third branch (3), the first rotation axis (311) of the fourth universal joint (21) is located on the fixed base (12), the second rotation axis (312) is perpendicular to the axis of the second sliding joint (22), the first rotation axis (311) of the fourth universal joint (21) is parallel to the second rotation axis (322) of the fifth universal joint (24), and the second rotation axis (312) of the fourth universal joint (21) is parallel to the first rotation axis (321) of the fifth universal joint (24). In the fourth branch (4), the first rotation axis (411) of the sixth universal joint (28) is located on the fixed base (12), and the rotation axis of the second rotating joint (26) is parallel to the second rotation axis (412) of the sixth universal joint (28).

4. The spatial rhomboid remote motion center mechanism according to claim 1, characterized in that, The rhomboid branch includes a third revolute joint (29) and a fourth revolute joint (31) connected to the first moving platform (17) and the second moving platform (5), a fifth revolute joint (33) connected to the third moving joint (39), and a sixth revolute joint (36) and a seventh revolute joint (34) connected to the rhomboid rod. The fifth branch includes an eighth revolute joint (38) connecting the rhomboid rod and a fifth revolute joint (33) connected to the third prismatic joint (39). The third rotary joint (29) and the first rotary joint (18) are mounted on the same rod, the fourth rotary joint (31) and the second rotary joint (26) are mounted on the same rod, and the sixth rotary joint (36), the seventh rotary joint (34), the fifth rotary joint (33), and the eighth rotary joint (38) form a rhomboid closed loop.

5. The spatial rhomboid remote motion center mechanism according to claim 1, characterized in that, The first branch (1) and the third branch (3) are symmetrically distributed relative to the intermediate plane determined by the RCM point in the initial state.

6. The spatial rhomboid remote motion center mechanism according to claim 1, characterized in that, The first rotation axis (111) of the first universal joint (13) in the first branch (1), the first rotation axis (211) of the third universal joint (20) in the second branch (2), the first rotation axis (311) of the fourth universal joint (21) in the third branch (3), and the first rotation axis (411) of the sixth universal joint (28) in the fourth branch (4) always remain parallel.

7. The spatial rhomboid remote motion center mechanism according to claim 1, characterized in that, The intersection of the axis of the link connecting the fifth rotating joint (33) and the eighth rotating joint (38) in the fifth branch with the first rotating axis (211) of the third universal joint (20) is the remote motion center point of the mechanism.

8. The spatial rhomboid remote motion center mechanism according to claim 1, characterized in that, The prismatic joints in the first branch (1) and the third branch (3) are driving joints, and the revolute joints in the second branch (2) and the fourth branch (4) are driving joints; when the driving joints move according to a certain pattern, the mechanism can realize two rotational movements around the remote center point and one prismatic movement along the remote center point.

9. The spatial rhomboid remote motion center mechanism according to claim 1, characterized in that, By changing the dimensional parameters of the moving platform, the position of the remote motion center point in space can be changed.

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