Two-rotation-one-movement decoupling parallel mechanism

Abstract

The present invention provides a parallel mechanism with two rotations and one movement decoupling, including a static platform, a dynamic platform and three branch kinematic chains, the three branch kinematic chains are respectively a first branch kinematic chain, a second branch kinematic chain and a third branch kinematic chain, the three branch kinematic chains cooperate with the static platform and the dynamic platform, so that the parallel mechanism in the present invention has three degrees of freedom, i.e., rotation in two directions and movement in one direction, and there is no coupling relationship between the movement degree of freedom and the two rotation degrees of freedom. The parallel mechanism has the advantages of simple structure, easy mechanism manufacturing and assembly, high precision, low cost, large working space, and movement flexibility, and has broad application prospects in many fields such as industry, medicine, and aerospace.

Description

Technical Field

[0001] The invention relates to the technical field of industrial robots, and in particular to a two-rotation-one-movement decoupling parallel mechanism. Background Art

[0002] A parallel mechanism is a group of mechanisms consisting of two or more branch mechanisms in parallel. Compared with a series mechanism, a parallel mechanism has the advantages of higher stiffness, smaller cumulative error, and greater load-bearing capacity. It has been widely used in food packaging, motion simulators, medical equipment, aerospace and other fields.

[0003] Due to the structural characteristics of parallel mechanisms, many problems will occur in the application process of parallel mechanisms, such as strong coupling, small working space, poor transmission performance, etc. Especially the influence of strong coupling, so achieving complete or partial decoupling of parallel mechanism motion has become a hot topic in international mechanism research.

[0004] In the past, most parallel mechanisms had six degrees of freedom. In recent years, parallel mechanisms with fewer degrees of freedom have attracted the attention of many scholars. Compared with six-degree-of-freedom parallel robot mechanisms, parallel mechanisms with fewer degrees of freedom have the advantages of simple mechanical structure and relatively low manufacturing and control costs.

[0005] At present, some scholars in my country have proposed three-degree-of-freedom parallel mechanisms, especially in the two-rotation-one-motion parallel mechanism. However, for most parallel mechanisms, there are still problems such as strong coupling and small working space, which to some extent hinder the development and application of parallel mechanisms. Summary of the invention

[0006] The purpose of the present invention is to provide a two-rotation-one-movement decoupling parallel mechanism to solve the problems of complex structure, complex spatial position of kinematic pairs and coupling between input and output existing in the two-rotation-one-movement parallel mechanism.

[0007] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a two-rotation-one-movement decoupling parallel mechanism, including a static platform, a dynamic platform and three branch kinematic chains, the three branch kinematic chains are respectively a first branch kinematic chain, a second branch kinematic chain and a third branch kinematic chain, wherein:

[0008] The first branch kinematic chain includes a first cylindrical pair connected to the static platform at one end, a universal joint connected to the dynamic platform at one end, and a first moving pair arranged between the two and connected to the two through a connecting rod, the axis of the first cylindrical pair is parallel to the inner axis of the universal joint, and the moving direction of the first moving pair is perpendicular to the axis of the first cylindrical pair;

[0009] The second branch kinematic chain comprises a second cylindrical pair, a first rotation pair and a ball pair which are sequentially connected by a connecting rod, the free ends of the second cylindrical pair and the ball pair are respectively connected to the static platform and the dynamic platform, and the axis of the second cylindrical pair is parallel to the axis of the first rotation pair;

[0010] The third branch kinematic chain includes a second moving pair, a third rotating pair and a second rotating pair connected in sequence by a connecting rod, free ends of the second moving pair and the second rotating pair are respectively connected to the static platform and the moving platform, and the axis of the third rotating pair is perpendicular to the axis of the second rotating pair and the moving direction of the second moving pair at the same time;

[0011] The first cylindrical pair, the second cylindrical pair and the second moving pair are all power input ends and are respectively connected to drive motors.

[0012] Furthermore, the movement direction of the second moving pair is perpendicular to the axis of the first cylindrical pair, and the axis of the first cylindrical pair is parallel to the axis of the third rotating pair.

[0013] Furthermore, the axis of the second cylindrical pair is perpendicular to both the axis of the first cylindrical pair and the movement direction of the second movable pair.

[0014] Furthermore, the outer axis of the universal joint is parallel to the axis of the second rotation pair.

[0015] Furthermore, the universal joint, the ball joint and the second revolute joint are arranged in sequence along the length direction of the moving platform, and the three are distributed on the same straight line.

[0016] Furthermore, two ends of the first movable pair are connected to the first cylindrical pair and the first universal joint through a first connecting rod and a second connecting rod respectively.

[0017] Furthermore, the second cylindrical pair and the first revolving pair, as well as the first revolving pair and the ball pair are connected via a third connecting rod and a fourth connecting rod respectively.

[0018] Furthermore, the second moving pair and the third rotating pair are connected via a fifth connecting rod and a sixth connecting rod, respectively, as well as the third rotating pair and the second moving pair are connected via a fifth connecting rod and a sixth connecting rod.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: the parallel mechanism in the present invention has three degrees of freedom, namely, rotation in two directions and movement in one direction, and there is no coupling relationship between the degree of freedom of movement and the two degrees of freedom of rotation. The parallel mechanism has the advantages of simple structure, easy mechanism manufacturing and assembly, high precision, low cost, large working space, and flexibility of movement, and has broad application prospects in multiple fields such as industry, medicine, and aerospace. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the overall structure of the present invention having two rotating and one moving decoupling parallel mechanisms;

[0021] Figure 2 It is a schematic diagram of the distribution of the universal joint, ball joint and second rotating joint on the moving platform. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0023] A parallel mechanism with two rotations and one movement decoupling, such as Figure 1 As shown, it includes a static platform 10 and a dynamic platform 20, and L1, L2, and L3 represent the first, second, and third branch motion chains respectively.

[0024] The first branch kinematic chain L1 includes a first cylindrical pair C11, a first mobile pair P12 and a universal joint U13, one end of the first cylindrical pair C11 and the universal joint U13 are directly connected to the fixed platform 10 and the movable platform 20 respectively, and the first mobile pair P12 is connected to the other ends of the first cylindrical pair C11 and the universal joint U13 through the first connecting rod 1-1 and the second connecting rod 1-2 respectively. Among them, the axis of the first cylindrical pair C11 is parallel to the axis connected to the second connecting rod 1-2 in the universal joint U13, that is, the inner axis, and the axis of the first cylindrical pair C11 is perpendicular to the moving direction of the first mobile pair P12.

[0025] The second branch motion chain L2 includes a second cylindrical pair C21, a first rotation pair R22 and a ball pair S23. The second cylindrical pair C21 and the ball pair S24 are directly connected to the fixed platform 10 and the movable platform 20 respectively. The first rotation pair R22 is connected to the second cylindrical pair C21 and the ball pair S24 through the third connecting rod 2-1 and the fourth connecting rod 2-2 respectively. The axis of the second cylindrical pair C21 is parallel to the axis of the first rotation pair R22.

[0026] The third branch kinematic chain L3 includes a second moving pair P31, a third rotating pair R32, and a second rotating pair R33. The second moving pair P31 and the second rotating pair R33 are connected to the fixed platform 10 and the moving platform 20 respectively, and the third rotating pair R32 is connected to the second moving pair P31 and the second rotating pair R33 through the fifth connecting rod 3-1 and the sixth connecting rod 3-2 respectively. The axis of the third rotating pair is perpendicular to the axis of the second rotating pair and the moving direction of the second moving pair at the same time;

[0027] In this embodiment, the movement direction of the second mobile pair P31 is perpendicular to the axis of the first cylindrical pair C11, and the axis of the first cylindrical pair C11 is parallel to the axis of the third rotation pair R32. The axis of the second cylindrical pair C21 is perpendicular to the axis of the first cylindrical pair C11 and the movement direction of the second mobile pair P31. The axis of the universal joint U13 connected to the moving platform 20, i.e., the outer axis, is parallel to the axis of the second rotation pair C21.

[0028] To further optimize this solution, Figure 2 As shown, the universal joint U13, the ball joint S23 and the second rotation joint C21 are sequentially arranged along the length direction of the moving platform 20, and the three are distributed on the same straight line. At the same time, the kinematic joints connected to the fixed platform 10 in the three branch kinematic chains are respectively selected as active joints. When they are cylindrical joints, their linear inputs are taken as active inputs. The parallel mechanism drives the active joints through the servo drive motor and provides power to the moving platform 20 through the three branch kinematic chains.

[0029] The control principle of the present invention is as follows: the first drive motor drives the first cylindrical pair C11 of the first branch motion chain L1, so that the moving platform 20 rotates along the second rotation pair R33; the second drive motor drives the second rotation pair C21 of the second branch motion chain L2, so that the moving platform 20 rotates along the third rotation pair R32; the third drive motor drives the second movement pair P31 of the third branch motion chain L3, so that the moving platform 20 moves along the moving direction of the second movement pair P31. Thus, the parallel mechanism can realize two rotations and one movement with three degrees of freedom. The present invention has the advantages of simple structure, easy mechanism manufacturing and assembly, high precision, low cost, large working space, and flexibility of movement, and has broad application prospects in many fields such as industry, medicine, and aerospace.

[0030] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. It has a two-rotation and one-movement decoupling parallel mechanism, including a static platform, a dynamic platform and three branch kinematic chains, characterized in that: The three branch kinematic chains are the first branch kinematic chain, the second branch kinematic chain and the third branch kinematic chain, where: The first branch kinematic chain includes a first cylindrical pair connected to the static platform at one end, a universal joint connected to the dynamic platform at one end, and a first moving pair arranged between the two and connected to the two through a connecting rod, the axis of the first cylindrical pair is parallel to the inner axis of the universal joint, and the moving direction of the first moving pair is perpendicular to the axis of the first cylindrical pair; The second branch kinematic chain comprises a second cylindrical pair, a first rotation pair and a ball pair which are sequentially connected by a connecting rod, the free ends of the second cylindrical pair and the ball pair are respectively connected to the static platform and the dynamic platform, and the axis of the second cylindrical pair is parallel to the axis of the first rotation pair; The third branch kinematic chain includes a second moving pair, a third rotating pair and a second rotating pair connected in sequence by a connecting rod, free ends of the second moving pair and the second rotating pair are respectively connected to the static platform and the moving platform, and the axis of the third rotating pair is perpendicular to the axis of the second rotating pair and the moving direction of the second moving pair at the same time; The first cylindrical pair, the second cylindrical pair and the second moving pair are all power input ends and are respectively connected to drive motors; The movement direction of the second movable pair is perpendicular to the axis of the first cylindrical pair, and the axis of the first cylindrical pair is parallel to the axis of the third rotating pair; the axis of the second cylindrical pair is perpendicular to the axis of the first cylindrical pair and the movement direction of the second movable pair at the same time; the outer axis of the universal joint is parallel to the axis of the second rotating pair; the universal joint, ball pair and second rotating pair are arranged in sequence along the length direction of the moving platform, and the three are distributed on the same straight line; the two ends of the first movable pair are connected to the first cylindrical pair and the first universal joint through the first connecting rod and the second connecting rod respectively; the second cylindrical pair and the first rotating pair and the first rotating pair and the ball pair are connected through the third connecting rod and the fourth connecting rod respectively.

2. The two-rotation-one-movement decoupling parallel mechanism according to claim 1, characterized in that: The second moving pair is connected to the third rotating pair, and the third rotating pair is connected to the second moving pair via a fifth connecting rod and a sixth connecting rod respectively.

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