A three-degree-of-freedom parallel mechanism with two plane movements and one rotation

Abstract

The present invention belongs to the technical field of industrial robots, and specifically discloses a three-degree-of-freedom parallel mechanism with two plane shifts and one rotation, comprising: a fixed platform and a moving platform; at least two motion branches are evenly distributed between the fixed platform and the moving platform; the motion branch comprises a motor, a first arc-shaped connecting rod and a second arc-shaped connecting rod, and the first arc-shaped connecting rod and the second arc-shaped connecting rod are bent in opposite directions; the fixed end of the motor is connected to the fixed platform, one end of the first arc-shaped connecting rod cooperates with the output end of the motor, one end of the second arc-shaped connecting rod cooperates with the moving platform, and the end of the first arc-shaped connecting rod away from the motor is slidably matched with the end of the second arc-shaped connecting rod away from the moving platform. The present invention has two kinematic pairs in the motion branch, which can improve the bearing capacity of the motion branch, avoid singular points, prevent jamming during operation, increase the working space of the parallel mechanism, and improve flexibility.

Description

Technical Field

[0001] The present invention belongs to the technical field of industrial robots, and in particular relates to a three-degree-of-freedom parallel mechanism with two plane movements and one plane rotation. Background Art

[0002] Parallel mechanisms are spatial multi-degree-of-freedom mechanisms. Their main feature is a multi-closed-loop structure formed by connecting a fixed platform and a moving platform via two or more branch chains. Compared to series mechanisms, parallel mechanisms offer advantages such as greater structural rigidity and load-bearing capacity, higher positioning accuracy, and easier control. Among them, the planar three-degree-of-freedom parallel mechanism can achieve two translational degrees of freedom and one rotational degree of freedom within a plane, and has higher rigidity and better dynamic performance. Therefore, it is often used in applications with heavy loads or high dynamic performance requirements, such as simulators, machine tools, and positioning platforms.

[0003] Among existing three-degree-of-freedom parallel mechanisms, patent application CN113771012A describes a spatial two-rotation, one-translation three-degree-of-freedom parallel mechanism, comprising three active kinematic branches. This mechanism boasts advantages such as a simple structure, high rigidity, good stability, and smooth motion. Patent application CN103406897A describes a two-translation, one-rotation three-degree-of-freedom parallel mechanism, employing three four-bar linkages and a T-shaped frame. This mechanism offers advantages such as simple kinematic forward and inverse solutions, a large workspace, high rigidity, a simple structure, and ease of manufacture. Patent application CN12861A proposes a three-degree-of-freedom planar virtual axis machine tool with three moving pairs. This planar three-degree-of-freedom parallel mechanism comprises a Class II rod group with three moving pairs, enabling four-axis linkage. The kinematic pairs in these three-degree-of-freedom parallel mechanisms utilize both revolute and translatory pairs, with their axes being parallel or coplanar. This results in excessive load-bearing capacity for the kinematic pairs (revolute / translatory pairs) between two adjacent links, significantly reducing workspace and flexibility, further impacting the overall performance of the mechanism. The patent application with publication number CN1104027A provides a 3-DOF parallel mechanism, which uses an arc-shaped moving pair instead of a pure moving pair. However, the parallel mechanism of this application has a limited working space, insufficient flexibility of the moving platform, and large inertia force, and still needs further improvement. Summary of the Invention

[0004] The purpose of the present invention is to provide a three-degree-of-freedom parallel mechanism with two plane translations and one rotation, so as to increase the working space of the parallel mechanism and improve its flexibility. The kinematics of the mechanism are simple to solve, the inertia force of the movement is small, the bearing capacity of the moving pair can be reduced, and singular points can be easily avoided.

[0005] To achieve the above objectives, the present invention adopts the following technical solutions:

[0006] A three-degree-of-freedom parallel mechanism with two plane movements and one rotation, comprising: a fixed platform and a movable platform; at least two kinematic branches are evenly arranged between the fixed platform and the movable platform;

[0007] The motion branch chain includes a motor, a first arc-shaped connecting rod and a second arc-shaped connecting rod, wherein the first arc-shaped connecting rod and the second arc-shaped connecting rod are arranged to be bent in opposite directions;

[0008] The fixed end of the motor is connected to the fixed platform, one end of the first arc-shaped connecting rod cooperates with the output end of the motor, one end of the second arc-shaped connecting rod cooperates with the moving platform, and the end of the first arc-shaped connecting rod away from the motor is movably cooperated with the end of the second arc-shaped connecting rod away from the moving platform. Specifically, the end of the first arc-shaped connecting rod away from the motor is slidingly cooperated with the second arc-shaped connecting rod, and the end of the second arc-shaped connecting rod away from the moving platform is slidingly cooperated with the first arc-shaped connecting rod.

[0009] By adopting the above technical solution, the motor drives the first arc-shaped connecting rod to rotate around the output shaft of the motor, so that the end of the first arc-shaped connecting rod away from the motor slides relative to the second arc-shaped connecting rod, and since the end of the second arc-shaped connecting rod away from the moving platform can also slide relative to the first arc-shaped connecting rod, the motion branch chain extends or contracts in its length direction. In addition, since the first arc-shaped connecting rod and the second arc-shaped connecting rod are bent in opposite directions, the moving platform can be driven to rotate during the sliding process of the two. That is to say, under the drive of the motor, the movement of the motion branch chain can realize three degrees of freedom: movement along the X and Y axes and rotation around the Z axis, and its rotation axis is not fixed.

[0010] Furthermore, since the first and second curved links can slide relative to each other, creating two kinematic pairs, the mutual influence of the two kinematic pairs during movement further enhances the kinematic branch's load-bearing capacity. The counter-bending arrangement of the first and second curved links also helps to further avoid singularities, prevent stalls during operation, increase the parallel mechanism's workspace, and enhance flexibility, finding applications in virtual axis machine tools, aviation simulation equipment, medical devices, and other fields.

[0011] According to one embodiment of the present invention, the first arc-shaped connecting rod is provided with a first arc-shaped groove, which extends along the arc length direction of the first arc-shaped connecting rod; the end of the second arc-shaped connecting rod away from the movable platform is slidably engaged with the first arc-shaped groove;

[0012] The second arc-shaped connecting rod is provided with a second arc-shaped groove, which extends along the arc length direction of the second arc-shaped connecting rod; the end of the first arc-shaped connecting rod away from the motor is in sliding engagement with the second arc-shaped groove.

[0013] Therefore, the first arc groove and the second arc groove are used to guide and limit the sliding process of the second arc connecting rod and the first arc connecting rod, which can ensure the smoothness of the moving platform's movement during the operation of the motion branch chain, prevent the moving platform from tilting, and ensure the planar movement of the parallel structure.

[0014] According to one embodiment of the present invention, a first pin is configured at the end of the first arc-shaped connecting rod away from the motor, and the first pin slides in conjunction with the second arc-shaped groove; a second pin is configured at the end of the second arc-shaped connecting rod away from the moving platform, and the second pin slides in conjunction with the first arc-shaped groove.

[0015] According to one embodiment of the present invention, the first arc-shaped groove and the second arc-shaped groove are both through grooves;

[0016] The first pin shaft is provided with a first limit piece at one end away from the first arc-shaped connecting rod; the first limit piece cooperates with the second arc-shaped groove; the second pin shaft is provided with a second limit piece at one end away from the second arc-shaped connecting rod, and the second limit piece cooperates with the first arc-shaped groove.

[0017] The first limit member and the second limit member can be respectively arranged at the ends of the first pin shaft and the second pin shaft, and respectively fit with the side of the second arc-shaped connecting rod away from the first arc-shaped connecting rod or fit with the side of the first arc-shaped connecting rod away from the second arc-shaped connecting rod; or, the first limit member and the second limit member can respectively fit with the second arc-shaped groove and the inner wall of the second arc-shaped groove to form a clamping structure to improve the fitting stability and fastening performance of the first arc-shaped connecting rod and the second arc-shaped connecting rod.

[0018] The first limiting member and the second limiting member can prevent the first arc-shaped connecting rod and the second arc-shaped connecting rod from deviating or derailing during operation, thereby improving structural stability and the overall performance of the parallel structure.

[0019] According to one embodiment of the present invention, a first pin hole is disposed at the end of the first curved connecting rod near the motor, and the first pin hole is connected to the output end of the motor. Specifically, the first pin hole can be sleeved onto the output shaft of the motor to achieve a fixed connection between the first curved connecting rod and the motor output shaft. In this manner, when the motor is started, the first curved connecting rod can be driven to rotate.

[0020] According to one embodiment of the present invention, a second pin hole is disposed at one end of the second arc-shaped connecting rod near the movable platform, a third pin shaft is disposed in the second pin hole, and the third pin shaft is connected to the movable platform, thereby achieving rotational coordination between the second arc-shaped connecting rod and the movable platform.

[0021] According to one embodiment of the present invention, the arc lengths of the first arc-shaped connecting rod and the second arc-shaped connecting rod are equal; and the radii of the first arc-shaped connecting rod and the second arc-shaped connecting rod are equal.

[0022] According to one embodiment of the present invention, the arc lengths of the first arc-shaped connecting rod and the second arc-shaped connecting rod are not equal; and the radii of the first arc-shaped connecting rod and the second arc-shaped connecting rod are not equal.

[0023] In this way, by setting the arc length and radius of the first arc-shaped connecting rod and the second arc-shaped connecting rod according to the needs of the application scenario, the activity space and operation sensitivity of the parallel mechanism can be adjusted.

[0024] According to one aspect of the present invention, a directional adjustment device is provided, comprising any one of the above-mentioned three-degree-of-freedom parallel mechanisms with two plane movements and one rotation, which can be used for directional adjustment of satellite antennas or solar panels, or for sorting express delivery, food, etc., or for other adjustment scenarios.

[0025] According to one aspect of the present invention, a surgical robot is provided, comprising any one of the above-mentioned three-DOF parallel mechanisms with two-planar translations and one-rotation, which can be used for planar positioning and posture adjustment of instruments in ophthalmic or minimally invasive surgeries.

[0026] Compared with the prior art, the present invention has at least the following beneficial effects:

[0027] 1. The present invention has a simple and reliable structure. It utilizes the interaction between the first and second curved connecting rods that are arranged in reverse bending to realize the movement of the moving platform along the X and Y axes and the rotation around the Z axis. There are two kinematic pairs between the first and second curved connecting rods, thereby reducing the load-bearing capacity of the kinematic pairs during operation and improving the overall load-bearing capacity of the kinematic branch chain.

[0028] 2. The first arc-shaped connecting rod and the second arc-shaped connecting rod of the present invention are bent in opposite directions and coupled with each other, which also helps to further avoid singular points, prevent jamming during operation, increase the working space of the parallel mechanism, and improve flexibility. It can be applied to virtual axis machine tools, aviation simulation equipment, medical equipment and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0030] Figure 1 Schematic diagram of the overall structure of a planar two-translation-one-rotation three-degree-of-freedom parallel mechanism according to Example 1 of the present invention;

[0031] Figure 2 This is a schematic structural diagram of the kinematic branch of a planar two-translation-one-rotation three-degree-of-freedom parallel mechanism according to Example 1 of the present invention;

[0032] Figure 3 This is a structural schematic diagram of the first arc-shaped connecting rod of the planar two-translation-one-rotation three-degree-of-freedom parallel mechanism of Example 1 of the present invention;

[0033] Figure 4 Schematic diagram of the contracted state of the kinematic branch of the planar two-translation-one-rotation three-degree-of-freedom parallel mechanism of Example 1 of the present invention;

[0034] Figure 5 Schematic diagram of the extended state of the motion branch of the planar two-translation-one-rotation three-degree-of-freedom parallel mechanism of Example 1 of the present invention.

[0035] Reference numerals: fixed platform 10 ; movable platform 20 ; motion branch chain 30 ; motor 41 ; output shaft 42 ; first arc-shaped connecting rod 51 ; first arc-shaped slot 52 ; second arc-shaped connecting rod 53 ; second arc-shaped slot 54 ; first pin 61 ; second pin 62 ; third pin 63 . DETAILED DESCRIPTION

[0036] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other.

[0037] The following detailed description is an exemplary description and is intended to provide further detailed description of the present invention. Unless otherwise indicated, all technical terms used in the present invention have the same meaning as those generally understood by those skilled in the art to which the present invention belongs. The terms used in the present invention are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention.

[0038] Example 1

[0039] A three-degree-of-freedom parallel mechanism with two plane translations and one rotation, such as Figure 1-Figure 5 As shown, it includes: a fixed platform 10 and a movable platform 20; the fixed platform 10 and the movable platform 20 are arranged in parallel, and at least two motion branches 30 are evenly distributed between them. In this embodiment, three motion branches 30 are arranged in a circular array between the fixed platform 10 and the movable platform 20.

[0040] The motion branch chain 30 includes a motor 41, a first arc-shaped link 51 and a second arc-shaped link 53, and the first arc-shaped link 51 and the second arc-shaped link 53 are arranged to be bent in opposite directions; in this embodiment, the arc length and radius of the first arc-shaped link 51 and the second arc-shaped link 53 are the same. In other embodiments, the arc length and radius of the first arc-shaped link 51 and the second arc-shaped link 53 can also be set to be different according to the needs of the application scenario.

[0041] The fixed end of the motor 41 is connected to the fixed platform 10, one end of the first arc-shaped connecting rod 51 cooperates with the output end of the motor 41, one end of the second arc-shaped connecting rod 53 cooperates with the movable platform 20, and the end of the first arc-shaped connecting rod 51 away from the motor 41 is movably cooperated with the end of the second arc-shaped connecting rod 53 away from the movable platform 20.

[0042] In this embodiment, three motors 41 are evenly distributed around the outer edge of the fixed platform 10, with their output shafts 42 facing the movable platform 20. A first pin hole is provided at the end of the first curved connecting rod 51 that engages with the motor 41. The first pin hole is sleeved onto the output shaft 42 of the motor 41, thereby securing the first curved connecting rod 51 to the output shaft 42 of the motor 41. Thus, when the motor 41 is activated, it can drive the first curved connecting rod 51 to rotate.

[0043] A second pin hole is disposed at one end of the second curved connecting rod 53 near the movable platform 20. A third pin shaft 63 is disposed within the second pin hole, and the third pin shaft 63 is connected to the movable platform 20. The third pin shaft 63 rotates relative to the second pin hole, enabling rotational coordination between the second curved connecting rod 53 and the movable platform 20. Furthermore, the second curved connecting rod 53 can drive the movable platform 20 to move during movement.

[0044] The first arc-shaped connecting rod 51 is provided with a first arc-shaped groove 52, which extends along the arc length direction of the first arc-shaped connecting rod 51; the second arc-shaped connecting rod 53 is provided with a second arc-shaped groove 54, which extends along the arc length direction of the second arc-shaped connecting rod 53; the first arc-shaped groove 52 and the second arc-shaped groove 54 are both through grooves.

[0045] The end of the first curved connecting rod 51 away from the motor 41 slides in the second curved slot 54; the end of the second curved connecting rod 53 away from the movable platform 20 slides in the first curved slot 52. Specifically, the end of the first curved connecting rod 51 away from the motor 41 is provided with a third pin hole, within which a first pin shaft 61 is fixedly sleeved, and the first pin shaft 61 slides in engagement with the second curved slot 54. The end of the second curved connecting rod 53 away from the movable platform 20 is provided with a fourth pin hole, within which a second pin shaft 62 is fixedly sleeved, and the second pin shaft 62 slides in engagement with the first curved slot 52.

[0046] Thus, driven by the motor 41, the end of the first curved link 51 away from the motor 41 slides relative to the second curved link 53. Since the end of the second curved link 53 away from the movable platform 20 can also slide relative to the first curved link 51, the kinematic branch 30 can extend or contract in its longitudinal direction. Furthermore, because the first curved link 51 and the second curved link 53 are arranged in opposite directions, their sliding motion can drive the movable platform 20 to rotate. In other words, driven by the motor 41, the kinematic branch 30 can achieve three degrees of freedom: movement along the X and Y axes and rotation about the Z axis, and its rotation axis is not fixed.

[0047] Because the first curved link 51 and the second curved link 53 can slide relative to each other, two kinematic pairs exist between them. The mutual influence of the two kinematic pairs during movement further enhances the bearing capacity of the kinematic branch chain 30. The counter-bending arrangement of the first and second curved links 51, 53 also helps to further avoid singularities, prevent stalls during operation, increase the working space of the parallel mechanism, and enhance flexibility. This approach has applications in virtual axis machine tools, aviation simulation equipment, medical equipment, and other fields.

[0048] Example 2

[0049] A three-degree-of-freedom parallel mechanism with two plane movements and one rotation, which differs from Example 1 in that: a first limit member is provided at one end of the first pin shaft 61 away from the first arc-shaped connecting rod 51; the first limit member cooperates with the second arc-shaped groove 54; a second limit member is provided at one end of the second pin shaft 62 away from the second arc-shaped connecting rod 53, and the second limit member cooperates with the first arc-shaped groove 52.

[0050] The first limit member and the second limit member can be respectively arranged at the ends of the first pin shaft 61 and the second pin shaft 62, and respectively fit with the side of the second arc-shaped link 53 away from the first arc-shaped link 51 or fit with the side of the first arc-shaped link 51 away from the second arc-shaped link 53; or, the first limit member and the second limit member can respectively cooperate with the second arc-shaped groove 54 and the inner wall of the second arc-shaped groove 54 to form a clamping structure to improve the fitting stability and fastening performance of the first arc-shaped link 51 and the second arc-shaped link 53.

[0051] The first limiting member and the second limiting member can prevent the first arc-shaped connecting rod 51 and the second arc-shaped connecting rod 53 from deflecting or derailing during operation, thereby improving structural stability and the overall performance of the parallel structure.

[0052] Example 3

[0053] A directional adjustment device includes the three-degree-of-freedom parallel mechanism with two plane movements and one rotation of Example 1 or Example 2, which can be used for directional adjustment of satellite antennas or solar panels, or for sorting express delivery, food, etc., or for other adjustment scenarios.

[0054] Example 4

[0055] A surgical robot comprises the three-degree-of-freedom parallel mechanism with two plane translations and one rotation of Example 1 or Example 2, and can be used for plane positioning and posture adjustment of instruments in ophthalmic or minimally invasive surgeries.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A three-degree-of-freedom parallel mechanism with two plane movements and one rotation, comprising a fixed platform (10) and a movable platform (20); characterized in that: At least two motion branches (30) are evenly distributed between the fixed platform (10) and the moving platform (20); The motion branch chain (30) comprises a motor (41), a first arc-shaped connecting rod (51) and a second arc-shaped connecting rod (53), wherein the first arc-shaped connecting rod (51) and the second arc-shaped connecting rod (53) are arranged to be bent in opposite directions; The fixed end of the motor (41) is connected to the fixed platform (10), one end of the first arc-shaped connecting rod (51) is matched with the output end of the motor (41), and one end of the second arc-shaped connecting rod (53) is matched with the moving platform (20). An end of the first arc-shaped connecting rod (51) away from the motor (41) and an end of the second arc-shaped connecting rod (53) away from the moving platform (20) are slidably engaged; The first arc-shaped connecting rod (51) is provided with a first arc-shaped groove (52), and the first arc-shaped groove (52) extends along the arc length direction of the first arc-shaped connecting rod (51); a first pin shaft (61) is provided at the end of the first arc-shaped connecting rod (51) away from the motor (41); the second arc-shaped connecting rod (53) is provided with a second arc-shaped groove (54), and the second arc-shaped groove (54) extends along the arc length direction of the second arc-shaped connecting rod (53); the first arc-shaped groove (52) and the second arc-shaped groove (54) are both through grooves; The end of the second arc-shaped connecting rod (53) away from the movable platform (20) is provided with a second pin shaft (62); the first pin shaft (61) is in sliding engagement with the second arc-shaped groove (54); the second pin shaft (62) is in sliding engagement with the first arc-shaped groove (52); A first stopper is provided at the end of the first pin shaft (61) away from the first arc-shaped connecting rod (51); the first stopper cooperates with the second arc-shaped groove (54); a second stopper is provided at the end of the second pin shaft (62) away from the second arc-shaped connecting rod (53); the second stopper cooperates with the first arc-shaped groove (52).

2. The planar two-translation-one-rotation three-degree-of-freedom parallel mechanism according to claim 1, characterized in that: The first arc-shaped connecting rod (51) is provided with a first pin hole at the end close to the motor (41), and the first pin hole is connected to the output end of the motor (41).

3. The planar two-translation-one-rotation three-degree-of-freedom parallel mechanism according to claim 1, characterized in that: A second pin hole is provided at one end of the second arc-shaped connecting rod (53) close to the movable platform (20), a third pin shaft (63) is provided in the second pin hole, and the third pin shaft (63) is connected to the movable platform (20).

4. The planar two-translation-one-rotation three-degree-of-freedom parallel mechanism according to claim 1, characterized in that: The arc lengths of the first arc-shaped connecting rod (51) and the second arc-shaped connecting rod (53) are equal; The radii of the first arc-shaped connecting rod (51) and the second arc-shaped connecting rod (53) are equal.

5. The planar two-translation-one-rotation three-degree-of-freedom parallel mechanism according to claim 1, characterized in that: The arc lengths of the first arc-shaped connecting rod (51) and the second arc-shaped connecting rod (53) are not equal; The radii of the first arc-shaped connecting rod (51) and the second arc-shaped connecting rod (53) are not equal.

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