A non-overconstrained four-degree-of-freedom parallel mechanism with hybrid branches

Abstract

The present invention relates to the field of robotics. The purpose is to provide a non-overconstrained four-degree-of-freedom parallel mechanism containing hybrid branches, which has the characteristics of simple structure, easy assembly, low manufacturing cost, smooth movement and long service life. The technical solution is a non-overconstrained four-degree-of-freedom parallel mechanism containing hybrid branches, including a frame, an end platform, a first intermediate platform, a second intermediate platform, a first rotating pair, a second rotating pair and four series branches with the same structure; wherein the first intermediate platform is connected to the end platform through a first rotating pair, and the second intermediate platform is connected to the end platform through a second rotating pair; two series branches are connected in parallel between the frame and the first intermediate platform, and the other two series branches are connected in parallel between the frame and the second intermediate platform.

Description

Technical Field

[0001] The invention relates to the technical field of robots, in particular to a non-overconstrained four-degree-of-freedom parallel mechanism with hybrid branches. Background Art

[0002] A parallel mechanism is usually a closed-loop mechanism with multiple degrees of freedom, consisting of a moving platform, a fixed platform, and two or more series branches connected to it. Compared with a series mechanism, a parallel mechanism has a series of advantages, such as high rigidity, small error, high precision, and strong load-bearing capacity. Due to the rise of industries such as express sorting and food packaging in recent years, parallel mechanisms have been widely used in various industries in society. An important branch of the parallel mechanism is the four-degree-of-freedom parallel mechanism, which belongs to a parallel mechanism with fewer degrees of freedom. Compared with the six-degree-of-freedom parallel mechanism, the four-degree-of-freedom parallel mechanism has a series of advantages, such as large working space, simple structure, and simple control.

[0003] In order to reduce production costs and simplify analysis, four-degree-of-freedom parallel mechanisms are usually designed as symmetrical structures (e.g., CN108481312). However, four-degree-of-freedom symmetrical parallel mechanisms often have over-constraints, which makes assembly difficult, and the internal forces caused by over-constraints will also reduce the service life of the machine. Therefore, it is necessary to propose a non-over-constrained four-degree-of-freedom parallel mechanism. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the background technology and propose a non-overconstrained four-degree-of-freedom parallel mechanism with a hybrid branch. The parallel mechanism has the characteristics of simple structure, easy assembly, low manufacturing cost, smooth movement and long service life.

[0005] The technical solution of the present invention is:

[0006] A non-overconstrained four-degree-of-freedom parallel mechanism with hybrid branches, comprising a frame, an end platform, a first intermediate platform, a second intermediate platform, a first rotation pair, a second rotation pair, and four series branches with the same structure; wherein the first intermediate platform is connected to the end platform through a first rotation pair, and the second intermediate platform is connected to the end platform through a second rotation pair; two series branches are connected in parallel between the frame and the first intermediate platform, and the other two series branches are connected in parallel between the frame and the second intermediate platform;

[0007] The series branch includes a mounting seat, a third rotation pair, a first connecting rod, a cross universal joint, a first moving pair and a fifth rotation pair which are sequentially connected between the frame and the first intermediate platform or the second intermediate platform; wherein the mounting seat is fixed on the frame, and the axis of the fifth rotation pair is parallel to the axis of the second rotating shaft of the universal joint and perpendicular to the axis of the first moving pair; or,

[0008] The series branch includes a mounting seat, a third rotation pair, a first connecting rod, a cross universal joint, a second connecting rod, a fourth rotation pair, a third connecting rod and a fifth rotation pair which are sequentially connected between the frame and the first intermediate platform or the second intermediate platform; wherein, the mounting seat is fixed to the frame, and the axes of the fourth rotation pair and the fifth rotation pair are parallel to the second axis of the universal joint.

[0009] Among the four series branches, two series branches connected to the first intermediate platform, the third rotation secondary axis intersects with the first axis of the universal joint at a point O in space. A ; Connect the two series branches of the second intermediate platform, the third rotation secondary axis intersects with the first axis of the universal joint at a point O in space B .

[0010] In the two series branches connected to the first intermediate platform, the two fifth rotation sub-axes intersect in the same plane; in the two series branches connected to the second intermediate platform, the two fifth rotation sub-axes intersect in the same plane.

[0011] The first intermediate platform is connected to the end platform through a first rotating pair, and the axis of the first rotating pair is parallel to the plane formed by the two rotating pair axes connected to the first intermediate platform; the second intermediate platform is connected to the end platform through a second rotating pair, and the axis of the second rotating pair is parallel to the plane formed by the two rotating pair axes connected to the second intermediate platform, and the first rotating pair axis is parallel to the second rotating pair axis.

[0012] The first moving pair is formed by a sleeve (10) and a telescopic rod (11).

[0013] The beneficial effects of the present invention are:

[0014] The mechanism proposed by the present invention does not contain redundant constraints, has four degrees of freedom, has the advantages of simple structure, easy assembly, low manufacturing cost, smooth movement, etc., and can be used in the fields of food and drug packaging, sorting, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the three-dimensional structure of the first embodiment of the present invention.

[0016] Figure 2 It is a schematic diagram of the three-dimensional structure of the second embodiment of the present invention.

[0017] Figure 3 It is a schematic diagram of the three-dimensional structure of the series branches in the first embodiment.

[0018] Figure 4 It is a schematic diagram of the three-dimensional structure of the series branches in the second embodiment. DETAILED DESCRIPTION

[0019] The present invention is further described below in conjunction with the accompanying drawings, but the present invention is not limited to the following embodiments.

[0020] Embodiment 1

[0021] like Figure 1 and Figure 3 As shown, a non-overconstrained four-DOF parallel mechanism with hybrid branches includes a frame (omitted in the figure), an end platform 1, a first intermediate platform 2, a second intermediate platform 3, a first rotation pair 4, a second rotation pair 5, and four series branches with the same structure. Among them, two series branches are connected in parallel between the frame and the first intermediate platform, and the remaining two series branches are connected in parallel between the frame and the second intermediate platform.

[0022] The series branch sequentially includes a mounting seat 6 connected between the first intermediate platform (or the second intermediate platform) and the frame, a third rotation pair 7, a first connecting rod 8, a cross universal joint 9, a sleeve 10, a telescopic rod 11 (the telescopic rod and the sleeve form a first moving pair) and a fifth rotation pair 12. The mounting seat and the frame are fixed, and the axis of the fifth rotation pair is parallel to the second axis of the universal joint and perpendicular to the axis of the first moving pair.

[0023] In the two series branches connected to the first intermediate platform, the third secondary axis of rotation intersects with the first axis of rotation of the universal joint at a point O A Similarly, in the two series branches connected to the second intermediate platform, the third rotation secondary axis intersects with the first axis of the universal joint at a point O B .

[0024] In the two series branches connected to the first intermediate platform, the two fifth rotation sub-axes intersect in the same plane; in the two series branches connected to the second intermediate platform, the two fifth rotation sub-axes intersect in the same plane.

[0025] The first intermediate platform is connected to the end platform via a first rotation pair, and the first rotation pair axis is parallel to the plane formed by the two rotation pair axes connected to the first intermediate platform. The second intermediate platform is connected to the end platform via a second rotation pair, and the second rotation pair axis is parallel to the plane formed by the two rotation pair axes connected to the second intermediate platform. The first rotation pair axis is parallel to the second rotation pair axis.

[0026] In this embodiment, the driving pair of the parallel mechanism can be the third rotating pair on each branch, and the driving method can be a reduction motor (omitted in the figure); by controlling the movement of the third rotating pair, the end platform can complete two rotations and two movements. Or the moving pair on each branch, the driving method can be a ball screw mechanism driven by a motor.

[0027] Embodiment 2

[0028] like Figure 2 and Figure 4 As shown, a non-overconstrained four-DOF parallel mechanism with hybrid branches includes a frame (omitted in the figure), an end platform 1, a first intermediate platform 2, a second intermediate platform 3, a first rotation pair 4, a second rotation pair 5, and four series branches. The structure of the second embodiment is similar to that of the first embodiment, except that the series branches of the second embodiment include a mounting seat 6 connected between the first intermediate platform (or the second intermediate platform) and the frame, a third rotation pair 7, a first connecting rod 8, a cross universal joint 9, a second connecting rod 13, a fourth rotation pair 14, a third connecting rod 15, and a fifth rotation pair 12. The axes of the fourth rotation pair and the fifth rotation pair are parallel to the second axis of the universal joint.

[0029] In this embodiment, the driving pair of the parallel mechanism can be the third rotating pair on each branch, and the driving method can be a reduction motor (omitted in the figure); by controlling the movement of the third rotating pair, the end platform can complete two rotations and two movements.

Claims

1. A non-overconstrained four-degree-of-freedom parallel mechanism with hybrid branches, comprising a frame, an end platform (1), a first intermediate platform (2), a second intermediate platform (3), a first rotation pair (4), a second rotation pair (5), and four series branches with the same structure; wherein: The first intermediate platform is connected to the end platform via a first rotating pair, and the second intermediate platform is connected to the end platform via a second rotating pair; two series branches are connected in parallel between the frame and the first intermediate platform, and the other two series branches are connected in parallel between the frame and the second intermediate platform; The series branch comprises a mounting seat (6), a third rotation pair (7), a first connecting rod (8), a cross universal joint (9), a first moving pair and a fifth rotation pair (12) which are sequentially connected between the frame and the first intermediate platform or the second intermediate platform; wherein the mounting seat is fixed on the frame, and the axis of the fifth rotation pair is parallel to the axis of the second rotating shaft of the universal shaft and perpendicular to the axis of the first moving pair; or, The series branch comprises a mounting seat (6), a third rotation pair (7), a first connecting rod (8), a cross universal joint (9), a second connecting rod (13), a fourth rotation pair (14), a third connecting rod (15) and a fifth rotation pair (12) which are sequentially connected between the frame and the first intermediate platform or the second intermediate platform; wherein the mounting seat is fixed to the frame, and the axes of the fourth rotation pair and the fifth rotation pair are parallel to the second axis of the universal joint.

2. The non-overconstrained four-degree-of-freedom parallel mechanism with hybrid branches according to claim 1, characterized in that: Among the four series branches, the two series branches connected to the first intermediate platform, the third rotation secondary axis intersects with the first axis of the universal joint at a point in space (O A ); connect the two series branches of the second intermediate platform, and the third rotation secondary axis intersects with the first axis of the universal joint at a point in space (O B ).

3. The non-overconstrained four-degree-of-freedom parallel mechanism with hybrid branches according to claim 2, characterized in that: In the two series branches connected to the first intermediate platform, the two fifth rotation sub-axes intersect in the same plane; in the two series branches connected to the second intermediate platform, the two fifth rotation sub-axes intersect in the same plane.

4. The non-overconstrained four-degree-of-freedom parallel mechanism with hybrid branches according to claim 3, characterized in that: The first intermediate platform is connected to the end platform through a first rotating pair, and the axis of the first rotating pair is parallel to the plane formed by the two rotating pair axes connected to the first intermediate platform; the second intermediate platform is connected to the end platform through a second rotating pair, and the axis of the second rotating pair is parallel to the plane formed by the two rotating pair axes connected to the second intermediate platform, and the first rotating pair axis is parallel to the second rotating pair axis.

5. The non-overconstrained four-degree-of-freedom parallel mechanism with hybrid branches according to claim 4, characterized in that: The first moving pair is formed by a sleeve (10) and a telescopic rod (11).

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