Planar two-movement and one-rotation three-degree-of-freedom parallel mechanism

Abstract

The invention belongs to the technical field of industrial robots, and particularly discloses a planar two-movement and one-rotation three-degree-of-freedom parallel mechanism which comprises a fixed platform and a movable platform. At least two motion branch chains are uniformly distributed between the fixed platform and the movable platform; the motion branch chain comprises a motor, a first arc-shaped connecting rod and a second arc-shaped connecting rod; the first arc-shaped connecting rod and the second arc-shaped connecting rod are arranged in a reverse bending manner; one end of the first arc-shaped connecting rod is matched with the output end of the motor, one end of the second arc-shaped connecting rod is matched with the movable platform, and the end, away from the motor, of the first arc-shaped connecting rod is in sliding fit with the end, away from the movable platform, of the second arc-shaped connecting rod. Two kinematic pairs exist in each kinematic branch chain, so that the bearing capacity of the kinematic branch chains can be improved, singular points are avoided, jamming in the operation process is prevented, the working space of the parallel mechanism is increased, and the flexibility is improved.

Description

Technical Field

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

[0002] The parallel mechanism is in the form of multiple degrees of freedom in space. Its main feature is that the fixed platform and the moving platform are connected by two or more branch chains to form a multi-closed-loop structure. Compared with the serial mechanism, the parallel mechanism has advantages such as greater structural stiffness and load-bearing capacity, higher positioning accuracy, and easier control. Among them, the three-degree-of-freedom parallel mechanism in a plane can achieve two translational degrees of freedom and one rotational degree of freedom in the plane, and has higher stiffness and better dynamic performance. Therefore, it is often applied to fields with large loads or high requirements for dynamic performance, such as simulators, machine tools, and positioning platforms.

[0003] Currently, among the existing three-degree-of-freedom parallel mechanisms, the patent application with the publication number CN113771012A is a three-degree-of-freedom parallel mechanism with two rotations and one translation in space, which includes three active motion branch chains and has advantages such as simple structure, large stiffness, good stability, and smooth motion; the patent application with the publication number CN103406897A is a three-degree-of-freedom parallel mechanism with two translations and one rotation. It adopts structures such as three four-bar mechanisms and a T-shaped frame and has advantages such as simple forward and inverse kinematic solutions, large working space, high stiffness, simple structure, and convenient manufacturing; the patent application with the publication number CN12861A proposes a three-degree-of-freedom planar virtual axis machine tool with three moving pairs, which contains a planar three-degree-of-freedom parallel mechanism of a II-level link group with three moving pairs and can achieve four-axis linkage. The kinematic pairs of these three-degree-of-freedom parallel mechanisms adopt rotational pairs and moving pairs, and the axes of these kinematic pairs are parallel or coplanar. The bearing capacity of the kinematic pair (rotational pair / moving pair) between two adjacent linkages is too large, and the working space and flexibility are significantly reduced, further affecting the overall performance of the mechanism. The patent application with the publication number CN1104027A provides a three-degree-of-freedom parallel mechanism, which uses an arc-shaped moving pair to replace the form of a pure moving pair. However, the working space of the parallel mechanism in this application is limited, the flexibility of the moving platform is insufficient, and the moving inertial force is large, and further improvement is still needed. Summary of the Invention

[0004] The purpose of the present invention is to provide a three-degree-of-freedom parallel mechanism with two translations and one rotation in a plane to increase the working space of the parallel mechanism, improve flexibility, and the kinematic solution of this mechanism is simple, the moving inertial force is small, the bearing capacity of the kinematic pair can be reduced, and it is easy to avoid singular points.

[0005] To achieve the above purpose, the present invention is implemented by adopting the following technical solutions: A three-degree-of-freedom parallel mechanism with two translations and one rotation in a plane, comprising: a fixed platform and a moving platform; at least two kinematic chains are evenly arranged between the fixed platform and the moving platform; The kinematic chain includes 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 is matched with the output end of the motor, one end of the second arc-shaped connecting rod is matched with the moving platform, and the end of the first arc-shaped connecting rod far from the motor is movably matched with the end of the second arc-shaped connecting rod far from the moving platform. Specifically, the end of the first arc-shaped connecting rod far from the motor is slidably matched with the second arc-shaped connecting rod, and the end of the second arc-shaped connecting rod far from the moving platform is slidably matched with the first arc-shaped connecting rod.

[0006] 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 far from the motor slides relative to the second arc-shaped connecting rod. And because the end of the second arc-shaped connecting rod far from the moving platform can also slide relative to the first arc-shaped connecting rod, the kinematic chain elongates 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, in this way, the moving platform can be driven to rotate during their sliding process. That is to say, under the drive of the motor, the movement of the kinematic chain can realize the three degrees of freedom of moving along the X and Y axes and rotating around the Z axis, and the axis of its rotation is not fixed.

[0007] Moreover, since both the first arc-shaped connecting rod and the second arc-shaped connecting rod can slide relative to each other, that is to say, there are two kinematic pairs between them. The two kinematic pairs affect each other during the movement process, which can further improve the bearing capacity of the kinematic chain. The reverse bending setting of the first arc-shaped connecting rod and the second arc-shaped connecting rod also helps to further avoid singular points, prevent jamming during operation, increase the working space of the parallel mechanism, improve flexibility, and can be applied to fields such as virtual-axis machine tools, aviation simulation equipment, and medical equipment.

[0008] According to an embodiment of the present invention, the first arc-shaped connecting rod is provided with a first arc-shaped groove, and the first arc-shaped groove extends along the arc length direction of the first arc-shaped connecting rod; the end of the second arc-shaped connecting rod far from the moving platform is slidably matched with the first arc-shaped groove; The second arc-shaped connecting rod is provided with a second arc-shaped groove, and the second arc-shaped groove extends along the arc length direction of the second arc-shaped connecting rod; the end of the first arc-shaped connecting rod far from the motor is slidably matched with the second arc-shaped groove.

[0009] Thus, the first arc-shaped groove and the second arc-shaped groove are used to guide and limit the sliding process of the second arc-shaped connecting rod and the first arc-shaped connecting rod, which can ensure the smoothness of the moving process of the moving platform during the operation of the kinematic chain, and can also prevent the moving platform from tilting, ensuring the planar movement of the parallel structure.

[0010] According to an embodiment of the present invention, a first pin shaft is arranged at the end of the first arc-shaped connecting rod away from the motor, and the first pin shaft is in sliding fit with the second arc-shaped groove; a second pin shaft is arranged at the end of the second arc-shaped connecting rod away from the moving platform, and the second pin shaft is in sliding fit with the first arc-shaped groove.

[0011] According to an embodiment of the present invention, both the first arc-shaped groove and the second arc-shaped groove are through grooves; One end of the first pin shaft away from the first arc-shaped connecting rod is provided with a first limiting member; the first limiting member is matched with the second arc-shaped groove; one end of the second pin shaft away from the second arc-shaped connecting rod is provided with a second limiting member, and the second limiting member is matched with the first arc-shaped groove.

[0012] The first limiting member and the second limiting member can be respectively arranged at the ends of the first pin shaft and the second pin shaft, and respectively fit with the side surfaces of the second arc-shaped connecting rod away from the first arc-shaped connecting rod or the side surfaces of the first arc-shaped connecting rod away from the second arc-shaped connecting rod; alternatively, the first limiting member and the second limiting member can respectively cooperate with the inner walls of the second arc-shaped groove and the second arc-shaped groove to form a clamping structure, so as to improve the cooperation stability and fastening performance between the first arc-shaped connecting rod and the second arc-shaped connecting rod.

[0013] By using the first limiting member and the second limiting member, it is possible to prevent the first arc-shaped connecting rod and the second arc-shaped connecting rod from shifting or derailing during operation, improve the structural stability, and improve the overall performance of the parallel structure.

[0014] According to an embodiment of the present invention, a first pin hole is arranged at the end of the first arc-shaped connecting rod close to the motor, and the first pin hole is connected to the output end of the motor. Specifically, the first pin hole can be sleeved on the output shaft of the motor to realize the fixed connection between the first arc-shaped connecting rod and the output shaft of the motor. In this way, after the motor is started, it can drive the first arc-shaped connecting rod to rotate.

[0015] According to an embodiment of the present invention, a second pin hole is arranged at one end of the second arc-shaped connecting rod close to the moving platform, and a third pin shaft is arranged in the second pin hole, and the third pin shaft is connected to the moving platform. In this way, the rotational cooperation between the second arc-shaped connecting rod and the moving platform can be realized.

[0016] According to an embodiment of the present invention, the arc lengths of the first arc-shaped connecting rod and the second arc-shaped connecting rod are equal; the radii of the first arc-shaped connecting rod and the second arc-shaped connecting rod are equal.

[0017] According to an 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; the radii of the first arc-shaped connecting rod and the second arc-shaped connecting rod are not equal.

[0018] In this way, according to the needs of the application scenario, by setting the arc lengths and radii of the first arc-shaped connecting rod and the second arc-shaped connecting rod, the adjustment of the moving space and operation sensitivity of the parallel mechanism can be realized.

[0019] According to one aspect of the present invention, a directional adjustment device is provided, which includes any one of the above-mentioned three-degree-of-freedom parallel mechanisms with two translations and one rotation in a plane, and can be used for directional adjustment of satellite antennas or solar panels, etc., or for sorting of express deliveries, food, etc., or for other adjustment scenarios.

[0020] According to one aspect of the present invention, a surgical robot is provided, which includes any one of the above-mentioned three-degree-of-freedom parallel mechanisms with two translations and one rotation in a plane, and can be used for planar positioning and attitude adjustment of instruments in ophthalmic or minimally invasive surgeries.

[0021] Compared with the prior art, the present invention has at least the following beneficial effects: 1. The structure of the present invention is simple and reliable. By the interaction of the first arc-shaped link and the second arc-shaped link arranged in reverse bending, the movement of the moving platform along the X and Y axes and the rotation around the Z axis are realized. There are two kinematic pairs between the first arc-shaped link and the second arc-shaped link, thereby reducing the bearing capacity of the kinematic pair during operation and improving the overall bearing capacity of the kinematic chain.

[0022] 2. The first arc-shaped link and the second arc-shaped link of the present invention are arranged in reverse bending and are mutually coupled, which also helps to further avoid singular points, prevent jamming during operation, increase the working space of the parallel mechanism, improve flexibility, and can be applied to fields such as virtual-axis machine tools, aviation simulation equipment, and medical equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The specification drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings: Figure 1 is the overall structural schematic diagram of the three-degree-of-freedom parallel mechanism with two translations and one rotation in a plane according to Embodiment 1 of the present invention; Figure 2 is the structural schematic diagram of the kinematic chain of the three-degree-of-freedom parallel mechanism with two translations and one rotation in a plane according to Embodiment 1 of the present invention; Figure 3 is the structural schematic diagram of the first arc-shaped link of the three-degree-of-freedom parallel mechanism with two translations and one rotation in a plane according to Embodiment 1 of the present invention; Figure 4 is the schematic diagram of the contracted state of the kinematic chain of the three-degree-of-freedom parallel mechanism with two translations and one rotation in a plane according to Embodiment 1 of the present invention; Figure 5 is the schematic diagram of the extended state of the kinematic chain of the three-degree-of-freedom parallel mechanism with two translations and one rotation in a plane according to Embodiment 1 of the present invention.

[0024] Reference numerals: fixed platform 10; moving platform 20; kinematic chain 30; motor 41; output shaft 42; first arc-shaped connecting rod 51; first arc-shaped groove 52; second arc-shaped connecting rod 53; second arc-shaped groove 54; first pin shaft 61; second pin shaft 62; third pin shaft 63. Detailed implementation mode

[0025] The present invention will be described in detail below with reference to the drawings and in conjunction with embodiments. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0026] The following detailed descriptions are all exemplary descriptions, aiming to provide further detailed descriptions of the present invention. Unless otherwise specified, all technical terms adopted by the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs. The terms used in the present invention are only for describing specific implementation modes, and are not intended to limit the exemplary implementation modes according to the present invention.

[0027] Embodiment 1 A three-degree-of-freedom parallel mechanism with two translations and one rotation in a plane, as Figures 1 - 5 shown, includes: a fixed platform 10 and a moving platform 20; the fixed platform 10 and the moving platform 20 are arranged in parallel, and at least two kinematic chains 30 are evenly distributed therebetween. In this embodiment, three kinematic chains 30 are arranged in a circumferential array between the fixed platform 10 and the moving platform 20.

[0028] The kinematic chain 30 includes a motor 41, a first arc-shaped connecting rod 51 and a second arc-shaped connecting rod 53, and the first arc-shaped connecting rod 51 and the second arc-shaped connecting rod 53 are bent in opposite directions; in this embodiment, the arc lengths and radii of the first arc-shaped connecting rod 51 and the second arc-shaped connecting rod 53 are the same, and in other embodiments, the arc lengths and radii of the first arc-shaped connecting rod 51 and the second arc-shaped connecting rod 53 can also be set to be different according to the needs of the application scenario.

[0029] 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, one end of the second arc-shaped connecting rod 53 is matched with the moving platform 20, and the end of the first arc-shaped connecting rod 51 far from the motor 41 is movably matched with the end of the second arc-shaped connecting rod 53 far from the moving platform 20.

[0030] In this embodiment, the three motors 41 are evenly and dispersedly arranged on the outer edge of the fixed platform 10, and their output shafts 42 are arranged towards the moving platform 20. A first pin hole is provided at the end of the first arc-shaped connecting rod 51 that is matched with the motor 41, and the first pin hole is sleeved on the output shaft 42 of the motor 41 to achieve the fixed connection between the first arc-shaped connecting rod 51 and the output shaft 42 of the motor 41. In this way, after the motor 41 is started, it can drive the first arc-shaped connecting rod 51 to rotate.

[0031] One end of the second arc-shaped connecting rod 53 close to the moving platform 20 is provided with a second pin hole, and a third pin shaft 63 is arranged in the second pin hole. The third pin shaft 63 is connected to the moving platform 20. The third pin shaft 63 rotates relative to the second pin hole, which can realize the rotational cooperation between the second arc-shaped connecting rod 53 and the moving platform 20. Moreover, during the movement of the second arc-shaped connecting rod 53, it can drive the moving platform 20 to move.

[0032] 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; 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; both the first arc-shaped groove 52 and the second arc-shaped groove 54 are through grooves.

[0033] The end of the first arc-shaped connecting rod 51 far from the motor 41 slides with the second arc-shaped groove 54; the end of the second arc-shaped connecting rod 53 far from the moving platform 20 slides with the first arc-shaped groove 52. Specifically, the end of the first arc-shaped connecting rod 51 far from the motor 41 is provided with a third pin hole, and a first pin shaft 61 is fixedly sleeved in the third pin hole. The first pin shaft 61 slides with the second arc-shaped groove 54; the end of the second arc-shaped connecting rod 53 far from the moving platform 20 is provided with a fourth pin hole, and a second pin shaft 62 is fixedly sleeved in the fourth pin hole. The second pin shaft 62 slides with the first arc-shaped groove 52.

[0034] Thus, driven by the motor 41, the end of the first arc-shaped connecting rod 51 far from the motor 41 slides relative to the second arc-shaped connecting rod 53. And because the end of the second arc-shaped connecting rod 53 far from the moving platform 20 can also slide relative to the first arc-shaped connecting rod 51, the motion branch chain 30 elongates or contracts in its length direction. And because the first arc-shaped connecting rod 51 and the second arc-shaped connecting rod 53 are bent in opposite directions, in this way, the moving platform 20 can be driven to rotate during their sliding. That is to say, driven by the motor 41, the movement of the motion branch chain 30 can realize three degrees of freedom of movement along the X and Y axes and rotation around the Z axis, and the axis of its rotation is not fixed.

[0035] Since both the first arc-shaped connecting rod 51 and the second arc-shaped connecting rod 53 can slide relative to each other, that is to say, there are two kinematic pairs between them. The two kinematic pairs affect each other during the movement, which can further improve the bearing capacity of the motion branch chain 30. The opposite bending settings of the first arc-shaped connecting rod 51 and the second arc-shaped connecting rod 53 also help to further avoid singular points, prevent jamming during operation, increase the working space of the parallel mechanism, improve flexibility, and can be applied to fields such as virtual-axis machine tools, aviation simulation equipment, and medical equipment.

[0036] Embodiment 2 A three-degree-of-freedom parallel mechanism with two translations and one rotation in a plane, which is different from that of Embodiment 1 in that: a first limiting member is arranged at one end of the first pin shaft 61 away from the first arc-shaped connecting rod 51; the first limiting member is matched with the second arc-shaped groove 54; a second limiting member is arranged at one end of the second pin shaft 62 away from the second arc-shaped connecting rod 53, and the second limiting member is matched with the first arc-shaped groove 52.

[0037] The first limiting member and the second limiting 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 surface of the second arc-shaped connecting rod 53 away from the first arc-shaped connecting rod 51 or the side surface of the first arc-shaped connecting rod 51 away from the second arc-shaped connecting rod 53; alternatively, the first limiting member and the second limiting member can respectively cooperate with the inner wall of the second arc-shaped groove 54 and the second arc-shaped groove 54 to form a clamping structure, so as to improve the cooperation stability and fastening performance between the first arc-shaped connecting rod 51 and the second arc-shaped connecting rod 53.

[0038] By using the first limiting member and the second limiting member, it is possible to prevent the first arc-shaped connecting rod 51 and the second arc-shaped connecting rod 53 from shifting or derailing during operation, improve the structural stability, and improve the overall performance of the parallel structure.

[0039] Embodiment 3 A directional adjustment device includes the three-degree-of-freedom parallel mechanism with two translations and one rotation in a plane of Embodiment 1 or Embodiment 2, and can be used for the directional adjustment of satellite antennas or solar panels, etc., or for sorting in express delivery, food, etc., or for other adjustment scenarios.

[0040] Embodiment 4 A surgical robot includes the three-degree-of-freedom parallel mechanism with two translations and one rotation in a plane of Embodiment 1 or Embodiment 2, and can be used for the planar positioning and attitude adjustment of instruments in ophthalmic or minimally invasive surgeries, etc.

[0041] 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 them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: it is still possible to modify the specific implementation manners of the present invention or make equivalent replacements, and any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A three-degree-of-freedom parallel mechanism with two translations and one rotation in a plane, comprising a fixed platform (10) and a moving platform (20); characterized in that, At least two kinematic chains (30) are evenly arranged between the fixed platform (10) and the moving platform (20); The kinematic chain (30) includes a motor (41), a first arc-shaped connecting rod (51) and a second arc-shaped connecting rod (53), and the first arc-shaped connecting rod (51) and the second arc-shaped connecting rod (53) are arranged with reverse bends; 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), One end of the first arc-shaped connecting rod (51) far from the motor (41) is in sliding fit with one end of the second arc-shaped connecting rod (53) far from the moving platform (20).

2. The three-degree-of-freedom parallel mechanism with two translations and one rotation in a plane according to claim 1, characterized in that, 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); the end of the second arc-shaped connecting rod (53) far from the moving platform (20) is in sliding fit with the first arc-shaped groove (52); 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 end of the first arc-shaped connecting rod (51) far from the motor (41) is in sliding fit with the second arc-shaped groove (54).

3. The three-degree-of-freedom parallel mechanism with two translations and one rotation in a plane according to claim 2, characterized in that, The end of the first arc-shaped connecting rod (51) far from the motor (41) is provided with a first pin shaft (61), and the first pin shaft (61) is in sliding fit with the second arc-shaped groove (54); The end of the second arc-shaped connecting rod (53) far from the moving platform (20) is provided with a second pin shaft (62), and the second pin shaft (62) is in sliding fit with the first arc-shaped groove (52).

4. The three-degree-of-freedom parallel mechanism with two translations and one rotation in a plane according to claim 3, characterized in that, Both the first arc-shaped groove (52) and the second arc-shaped groove (54) are through grooves; A first limiting member is arranged at the end of the first pin shaft (61) far from the first arc-shaped connecting rod (51); the first limiting member is matched with the second arc-shaped groove (54); A second limiting member is arranged at the end of the second pin shaft (62) far from the second arc-shaped connecting rod (53), and the second limiting member is matched with the first arc-shaped groove (52).

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

6. The three-degree-of-freedom parallel mechanism with two translations and one rotation in a plane according to claim 1, wherein a second pin hole is provided at one end of the second arc-shaped connecting rod (53) close to the moving platform (20), a third pin shaft (63) is arranged in the second pin hole, and the third pin shaft (63) is connected to the moving platform (20).

7. The three-degree-of-freedom parallel mechanism with two translations and one rotation in a plane according to claim 1, wherein 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.

8. The three-degree-of-freedom parallel mechanism with two translations and one rotation in a plane according to claim 1, wherein 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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