A RPR planar three-degree-of-freedom parallel mechanism driven by a revolute pair R

Abstract

The present invention discloses an RPR planar three-degree-of-freedom parallel mechanism driven by a rotary pair R, comprising a moving platform, three RPR motion branches with completely identical structures, a fixed platform and a reduction box; each of the RPR motion branches comprises a driving rotary pair, a driven rotary pair and a driven moving pair; the planar three-degree-of-freedom parallel mechanism is driven by a driving rotary pair, the fixed platform is provided with a slide groove, and the driven moving pair is connected to the slide groove to improve the rigidity of the overall structure. The platform introduces a pulley support for the driven end of the driven moving pair, which increases the overall rigidity and stability. The mechanism is controlled by a servo motor to achieve precise positioning control of the three degrees of freedom in the planar, meeting the requirements of high-precision positioning control in a narrow space.

Description

Technical Field

[0001] The invention relates to the technical field of mechanical manufacturing, and in particular to an RPR planar three-degree-of-freedom parallel mechanism driven by a revolute pair R. Background Art

[0002] In the field of mechanical manufacturing technology, parallel mechanisms, as a new type of configuration that has emerged in recent decades, have attracted widespread attention and research, and are widely used in aerospace, industrial equipment, and precision positioning. Parallel mechanisms are a type of robot configuration, which is composed of parallel mechanisms. Compared with serial robots, they can withstand higher loads, and the end precision of parallel mechanisms is high and the structural rigidity is large, but the small working space limits the application of parallel robots. Through reasonable design, the high-precision positioning control of parallel mechanisms in a small working space can be brought into play, achieving better positioning effects.

[0003] Traditional planar three-degree-of-freedom parallel mechanisms mostly use the RRR configuration in which the rotating R pair is driven and also the R pair is driven. There is no configuration in which the mobile pair P is the driven end. In addition, the structure of the traditional parallel mechanism is not compact. Therefore, it is necessary to propose an RPR planar three-degree-of-freedom parallel mechanism driven by the rotating pair R, which expands the configuration design model of the planar three-degree-of-freedom mechanism, facilitates comparison with planar three-degree-of-freedom mechanisms of different configurations, and has a more compact structure. Summary of the invention

[0004] In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, an object of the present invention is to provide an RPR planar three-degree-of-freedom parallel mechanism driven by a revolute pair R.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] An RPR planar three-degree-of-freedom parallel mechanism driven by a revolute pair R comprises a moving platform, three RPR motion branches with identical structures, a fixed platform and a reduction box;

[0007] Each of the RPR motion branches includes a driving rotation pair, a driven rotation pair and a driven movement pair;

[0008] The planar three-degree-of-freedom parallel mechanism is driven by a driving rotating pair, a slide groove is arranged on the fixed platform, and the driven moving pair is connected to the slide groove to improve the rigidity of the overall structure.

[0009] Furthermore, the three RPR motion branches are arranged on the same circumference of the fixed platform at intervals of 120 degrees.

[0010] Furthermore, the slider and the optical axis form a movable driven moving pair; the fixed platform and the slider are connected through a shaft assembly with a bearing to form a driven rotating pair; the optical axis and the reduction box are connected through a right-angle connector to form a driving end rotating pair, the reduction box is connected to the servo motor, and the servo motor drives the RPR motion branch chain to move.

[0011] Furthermore, the optical axis is connected to a slide groove on the fixed platform through a module with a pulley.

[0012] Furthermore, the moving platform is a rotationally symmetrical triangle, and the corner points of the triangle are rounded.

[0013] Furthermore, the fixed platform is a rotationally symmetric triangle.

[0014] Furthermore, when the fixed platform is at the origin position, the mechanism presents a rotationally symmetric configuration.

[0015] Furthermore, the fixed platform is connected to the external flange through three identical brackets.

[0016] Furthermore, the moving platform has three degrees of freedom, namely two translational degrees of freedom within the plane where it is located and a rotational degree of freedom perpendicular to the plane where it is located.

[0017] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0018] The present invention proposes a novel planar three-degree-of-freedom parallel mechanism configuration RPR, which makes the overall parallel mechanism more compact through the P pair structure, and has a smaller footprint than other configurations in the same working space; the P pair driven end of the kinematic chain of the present invention is connected to the P pair by a pulley slideway structure, thereby improving the rigidity of the overall structure. The present invention uses a variety of standard parts such as linear bearings, reduction boxes, pulleys, optical axes, bearings, etc. for assembly, has interchangeability, and has a relatively low manufacturing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the structure of the present invention;

[0020] Figure 2 yes Figure 1 Top view of the . DETAILED DESCRIPTION

[0021] The present invention will be further described in detail below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

[0022] like Figure 1-Figure 2As shown, an RPR planar three-degree-of-freedom parallel mechanism driven by a revolute pair R is required to control the three-degree-of-freedom posture of the moving platform 1, that is, the translation of the moving platform along the x-direction and the y-direction and the rotation angle along the z-direction. By using the inverse kinematics relationship of the mechanism, the required rotation angle of the three input ends can be obtained, and the rotation angle is the output rotation angle of the reduction box 9. The rotation angle position required for the input of the three motors can be further solved through the reduction ratio relationship of the reduction box, thereby achieving the three-degree-of-freedom positioning control of the parallel mechanism.

[0023] Design a parallel mechanism in which the fixed platform 8 is a rotationally symmetrical triangle, and the corners of the triangle are rounded. At the same time, a slide groove is opened on the fixed platform for the driven moving pair P to pass through the support. The fixed platform 8 is connected to the external flange 12 through three identical brackets 11, and the bracket connection position is arranged in a rotationally symmetrical position relative to the flange 12. Design the parallel mechanism moving platform 1 to be a rotationally symmetrical triangle, and round the corners of the triangle.

[0024] The parallel mechanism needs to design three identical RPR motion branches, which are arranged on the same circumference of the fixed platform 8 at intervals of 120°. The structure of each motion branch is as follows: the moving platform 1 and the slider 3 on the driven moving pair P are connected through a shaft assembly 2 with a bearing to form a driven rotating pair R. The slider 3 and the optical axis 5 form a movable driven moving pair P. The optical axis 5 and the drive end reduction box 9 are fixedly connected through a right-angle connector 6 to form a drive end rotating pair R. The reduction box 9 is fixedly connected through a servo motor 10, and the servo motor 10 drives the entire motion chain to move. On the driven moving pair P, the optical axis 5 is connected to the slide groove on the fixed platform 8 through a module 7 with a pulley, which provides a certain support effect and increases the rigidity of the overall motion chain.

[0025] The working process of the parallel mechanism is that for a single motion branch chain, the control mechanism servo motor 10 drives the reduction box 9 to drive the parallel mechanism drive end rotary pair to move, and the movement of the drive end rotary pair further drives the rotation of the optical axis 5. Under the action of the rotation of the optical axis 5, the slider 3 moves in translation, and the shaft assembly 2 with bearings converts the translation into rotation to drive the movement of the moving platform 1. When the parallel mechanism is working, the rotation position of the three servo motors on the three motion branches is controlled to realize the planar three-degree-of-freedom movement of the moving platform 1.

[0026] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. An RPR planar three-degree-of-freedom parallel mechanism driven by a revolute pair R, characterized in that: It includes a moving platform, three RPR motion branches with identical structures, a fixed platform and a reduction box; Each of the RPR motion branches includes a driving rotation pair, a driven rotation pair and a driven movement pair; The slider and the optical axis form a movable driven moving pair; the fixed platform and the slider are connected through a shaft assembly with a bearing to form a driven rotating pair; The optical axis and the reduction box are connected by a right-angle connector to form a driving end rotation pair. The reduction box is connected to the servo motor, and the servo motor drives the RPR motion branch chain to move; The planar three-degree-of-freedom parallel mechanism is driven by a driving rotation pair, a slide groove is provided on the fixed platform, and the optical axis is connected to the slide groove on the fixed platform through a module with a pulley, thereby improving the rigidity of the overall structure; The dynamic platform has three degrees of freedom, namely two translational degrees of freedom in the plane in which it is located and a rotational degree of freedom perpendicular to the plane in which it is located.

2. The RPR planar three-degree-of-freedom parallel mechanism according to claim 1, characterized in that: The three RPR motion branches are arranged on the same circumference of the fixed platform at intervals of 120 degrees.

3. The RPR planar three-degree-of-freedom parallel mechanism according to any one of claims 1 to 2, characterized in that: The moving platform is a rotationally symmetrical triangle, and the corner points of the triangle are rounded.

4. The RPR planar three-degree-of-freedom parallel mechanism according to claim 3, characterized in that: The fixed platform is a rotationally symmetrical triangle.

5. The RPR planar three-degree-of-freedom parallel mechanism according to claim 1, characterized in that: When the fixed platform is at the origin, the mechanism presents a rotationally symmetrical configuration.

6. The RPR planar three-degree-of-freedom parallel mechanism according to claim 1, characterized in that: The fixed platform is connected to the external flange through three identical brackets.

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