A two-rotation-one-translation low-profile parallel mechanism with three constrained branches

Abstract

The present invention discloses a two-turn and one-shift low-profile parallel mechanism containing three constraint branches, which belongs to the technical field of antenna parallel structure. It includes a base, a moving platform, and three driving branches and three constraint branches connecting the base and the moving platform; the three driving branches are distributed on the three vertices of an equilateral triangle, and in the initial state, the axes of the three driving branches are parallel to each other and perpendicular to the base and the moving platform respectively; the three constraint branches are distributed in the same plane, wherein two constraint branches are parallel to each other and perpendicular to the third constraint branch. The three driving branch configurations of the present invention are all SPS structures, and the three constraint branch configurations are all SS structures. The present invention has the characteristics of large bearing capacity, and the cross-section between the base and the moving platform is low, and the driving branches and the constraint branches are both two-force rods, and the force is uniform and stable.

Description

Technical Field

[0001] The invention belongs to the technical field of antenna parallel mechanisms, and in particular refers to a two-rotation-one-translation low-profile parallel mechanism with three constrained branches. Background Art

[0002] Parallel mechanisms are generally composed of a base and a moving platform connected by multiple branches. Compared with serial mechanisms, parallel mechanisms have the characteristics of compact structure, high rigidity, strong load-bearing capacity, and small cumulative error. Therefore, they are widely used in motion simulation, motion compensation, posture adjustment and other fields. However, it is difficult for parallel mechanisms with few degrees of freedom to have the characteristics of low profile, large load-bearing capacity, and only tensile and compressive force on the driving branches, which limits the application and promotion of parallel mechanisms to a certain extent.

[0003] The two-rotation-one-transfer parallel mechanism is a mechanism with few degrees of freedom. Generally, its cross-section is high, and the driving branch will be subjected to bending moment while bearing tension and pressure, which is not suitable for use under large load conditions. For example, the 3RSR parallel mechanism uses the rotating pair as the driving pair, and its load-bearing capacity is greatly limited. Although the load-bearing capacity of the 3RPS parallel mechanism is improved, its cross-section is high, and the driving branch will also be subjected to bending moment. Summary of the invention

[0004] In view of this, the present invention proposes a two-rotation-one-translation low-profile parallel mechanism containing three constrained branches. The parallel mechanism has the characteristics of large bearing capacity and low profile, and can realize a two-rotation-one-translation movement mode.

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

[0006] A two-rotation-one-translation low-profile parallel mechanism with three constraint branches comprises a base and a moving platform; in addition, it also comprises three driving branches and three constraint branches, wherein the driving branches are telescopic rods, and the driving branches and the constraint branches are respectively connected to the base and the moving platform through ball joints at both ends; in an initial state, the three driving branches are distributed on the three vertices of an equilateral triangle, the three driving branches are parallel to each other and perpendicular to the base and the moving platform, two of the three constraint branches are parallel to each other and perpendicular to the third constraint branch, and the three constraint branches are parallel to the base and the moving platform.

[0007] Furthermore, the center distances between the ball joints at both ends of the three constraint branches are equal.

[0008] Furthermore, three brackets are provided on the base, one end of the constraint branch is connected to the moving platform through a ball joint, and the other end is connected to a bracket on the base through a ball joint.

[0009] Furthermore, the telescopic rod is a sleeve-piston rod structure.

[0010] Compared with the prior art, the present invention has the following advantages:

[0011] 1. The present invention has a simple structure, low cost and is easy to manufacture.

[0012] 2. The present invention achieves the characteristics of low profile and good branch force bearing while retaining the strong load-bearing capacity, compact structure and good stability of the parallel mechanism. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Schematic diagram of the structure of the parallel mechanism in an embodiment of the present invention.

[0014] Figure 2 for Figure 1 Schematic diagram of the structure of the middle drive branch.

[0015] Figure 3 for Figure 1 Schematic diagram of the structure of the constraint branch.

[0016] In the figure: 1, base, 2, first driving branch, 3, first constraint branch, 4, moving platform, 5, second constraint branch, 6, second driving branch, 7, third constraint branch, 8, third driving branch, 9, first ball joint, 10, sleeve, 11, piston rod, 12, second ball joint, 13, third ball joint, 14, constraint branch rod body, 15, fourth ball joint. DETAILED DESCRIPTION

[0017] The technical solution of the present invention is further described below in conjunction with the accompanying drawings.

[0018] like Figure 1 As shown, a two-turn one-shift low-profile parallel mechanism with three constraint branches includes a base 1, a moving platform 4, and a first driving branch 2, a second driving branch 6, a third driving branch 8 and a first constraint branch 3, a second constraint branch 5, and a third constraint branch 7 connecting the base 1 and the moving platform 4. Initially, the three driving branches are distributed on the three vertices of an equilateral triangle, and the axes of the three driving branches are parallel to each other and perpendicular to the base 1 and the moving platform 4. In addition, in the initial state, the three constraint branches are distributed in the same plane, and the plane is parallel to the base 1 and the moving platform 4, wherein two constraint branches are parallel to each other and perpendicular to the third constraint branch.

[0019] like Figure 2 As shown, the three drive branches are all SPS (Spherical pair-Prismatic pair-Spherical pair, spherical pair-movable pair-spherical pair) structures. Specifically, each drive branch includes a sleeve 10 and a piston rod 11, and the two ends of the drive branch are respectively provided with a first ball joint 9 and a second ball joint 12.

[0020] One end of the driving branch connects the sleeve 10 to the base 1 through the first ball joint 9, and the other end connects the piston rod 11 to the moving platform 4 through the second ball joint 12. The sleeve axis and the piston rod axis coincide and can move relatively to form a moving pair.

[0021] like Figure 3 As shown, the three constraint branches are all SS (Spherical pair-Spherical pair) structures. Specifically, each constraint branch includes a rod 14, and the two ends of the rod 14 are respectively provided with a third ball joint 13 and a fourth ball joint 15.

[0022] The three constraint branches have the same structure, equal length and are fixed and cannot be adjusted. One end of each constraint branch is connected to the bracket on the base 1 through the third ball joint 13, and the other end is connected to the moving platform 4 through the fourth ball joint 15. The center of the first ball joint and the center of the second ball joint of the constraint branch are distributed on the axis of the constraint branch, and the center distance of the two ball joints in each constraint branch is equal.

[0023] In summary, the present invention has the characteristics of large bearing capacity, and the cross-section between the base and the moving platform is low, the driving branch and the restraining branch are both two-force rods, and the force is uniform and stable.

Claims

1. A two-rotation-one-translation low-profile parallel mechanism with three constrained branches, comprising a base and a moving platform; characterized in that: It also includes three driving branches and three restraining branches, wherein the driving branches are telescopic rods, and the driving branches and the restraining branches are respectively connected to the base and the moving platform through ball joints at both ends; in an initial state, the three driving branches are distributed on three vertices of an equilateral triangle, the three driving branches are parallel to each other and perpendicular to the base and the moving platform, two of the three restraining branches are parallel to each other and perpendicular to the third restraining branch, and the three restraining branches are parallel to the base and the moving platform; The center distances between the ball joints at both ends of the three constraint branches are equal; The base is provided with three brackets, one end of the constraint branch is connected to the moving platform through a ball joint, and the other end is connected to a bracket on the base through a ball joint.

2. A two-rotation-one-translation low-profile parallel mechanism with three constraint branches according to claim 1, characterized in that: The telescopic rod is a sleeve-piston rod structure.

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