CN115502957A - Non-overconstrained four-degree-of-freedom parallel mechanism with parallel-series branches - Google Patents

Abstract

The invention relates to the technical field of robots. The parallel mechanism has the characteristics of simple structure, easiness in assembly, low manufacturing cost, stability in motion and long service life. The technical scheme is that the non-overconstrained four-degree-of-freedom parallel mechanism with the parallel-series branches comprises a rack, a tail end platform, a first middle platform, a second middle platform, a first rotating pair, a second rotating pair and four series branches with the same structure; the first middle platform is connected with the tail end platform through a first revolute pair, and the second middle platform is connected with the tail end platform through a second revolute 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

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

technical field

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 technique

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

In order to reduce the production cost and simplify the analysis, the four-degree-of-freedom parallel mechanism is usually designed as a symmetrical structure (for example, CN108481312). However, the four-degree-of-freedom symmetric parallel mechanism often has over-constraints, which makes assembly difficult, and the internal force caused by over-constraints will also reduce the service life of the machine. Therefore, it is necessary to propose a non-overconstrained four-degree-of-freedom parallel mechanism.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the deficiencies of the background technology and propose a non-overconstrained four-degree-of-freedom parallel mechanism with hybrid branches. The parallel mechanism has the advantages of simple structure, easy assembly, low manufacturing cost, stable movement, and long service life. long features.

Technical scheme of the present invention is:

A non-overconstrained four-degree-of-freedom parallel mechanism with hybrid branches, including a frame, an end platform, a first intermediate platform, a second intermediate platform, a first revolving pair, a second revolving pair, and four series branches with the same structure ; Wherein, the first intermediate platform is connected with the end platform through the first rotating pair, and the second intermediate platform is connected with the end platform through the second rotating pair; two series branches are connected in parallel between the frame and the first intermediate platform, and the other two a series branch is connected in parallel between the rack and the second intermediate platform;

The series branch includes an installation seat connected in sequence between the frame and the first intermediate platform or the second intermediate platform, the third rotating pair, the first connecting rod, the universal joint, the first moving pair and the fifth rotating pair ; Wherein, the mounting seat is fixed on the frame, and the axis of the fifth rotating pair is parallel to the axis of the second rotating shaft of the universal joint and perpendicular to the axis of the first moving auxiliary; or,

The series branch includes a mounting seat connected in sequence between the frame and the first intermediate platform or the second intermediate platform, a third rotating pair, a first connecting rod, an Oldham joint, a second connecting rod, and a fourth rotating pair , the third connecting rod and the fifth rotating pair; wherein, the mounting seat is fixed to the frame, and the axes of the fourth rotating pair and the fifth rotating pair are parallel to the second axis of the universal joint.

Among the four series branches, the two series branches connected to the first intermediate platform, the third axis of rotation and the first axis of the universal joint intersect at a point _OA in space; the two series branches connected to the second intermediate platform, The axis of the third rotating pair intersects the first axis of the universal joint at a point _OB in space.

In the two series branches connected to the first intermediate platform, the axes of the two fifth rotating pairs intersect in the same plane; in the two series branches connected to the second intermediate platform, the axes of the two fifth rotating pairs intersect in the same plane.

The first intermediate platform is connected to the end platform through the first rotating pair, and the axis of the first rotating pair is parallel to the plane formed by the axes of the two rotating pairs connected to the first intermediate platform; the second intermediate platform is passed through the second The rotary pair is connected to the end platform, the axis of the second rotary pair is parallel to the plane formed by the axes of the two rotary pairs connected to the second intermediate platform, and the axis of the first rotary pair is parallel to the axis of the second rotary pair.

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

The beneficial effects of the present invention are:

The mechanism proposed by the invention does not contain redundant constraints, has four degrees of freedom, has the advantages of simple structure, easy assembly, low manufacturing cost, and stable movement, and can be used in the fields of food and drug packaging and sorting.

Description of drawings

Fig. 1 is a schematic perspective view of the first embodiment of the present invention.

Fig. 2 is a schematic perspective view of the second embodiment of the present invention.

Fig. 3 is a schematic diagram of the three-dimensional structure of the series branch in the first embodiment.

Fig. 4 is a schematic perspective view of the three-dimensional structure of the series branch in the second embodiment.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings, but the present invention is not limited to the following examples.

Embodiment one

As shown in Figures 1 and 3, a non-overconstrained four-degree-of-freedom 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, The first revolving pair 4, the second revolving pair 5 and four series branches with the same structure. Wherein, two series branches are connected in parallel between the rack and the first intermediate platform, and the other two series branches are connected in parallel between the rack and the second intermediate platform.

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

Of the two series branches connected to the first intermediate platform, the axis of the third rotary joint intersects the axis of the first rotary shaft of the universal joint at a point _OA . Similarly, in the two series branches connected to the second intermediate platform, the axis of the third rotary joint intersects the first axis of the universal joint at a point _OB .

In the two series branches connected to the first intermediate platform, the axes of the two fifth rotating pairs intersect in the same plane; in the two series branches connected to the second intermediate platform, the axes of the two fifth rotating pairs intersect in the same plane.

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 axes of the two rotating pairs 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 axes of the two rotating pairs connected to the second intermediate platform. The first rotary joint axis is parallel to the second rotary joint axis.

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 geared motor (omitted in the figure); by controlling the movement of the third rotating pair, the end platform can complete two rotations and two rotations. Movement of movement. Or it is a moving pair on each branch, and the driving mode can be a ball screw mechanism driven by a motor.

Embodiment two

As shown in Figures 2 and 4, a non-overconstrained four-degree-of-freedom 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, The first revolving pair 4, the second revolving pair 5 and four series branches. The structure of the second embodiment is similar to the structure of the first embodiment, the difference is that the series branch of the second embodiment sequentially includes the mounting seat 6 connected between the first intermediate platform (or the second intermediate platform) and the frame, the second Three rotating pairs 7 , a first connecting rod 8 , an Oldham joint 9 , a second connecting rod 13 , a fourth rotating pair 14 , a third connecting rod 15 , and a fifth rotating pair 12 . Wherein, the axes of the fourth rotating pair and the fifth rotating pair are parallel to the second axis of the universal joint.

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 geared motor (omitted in the figure); by controlling the movement of the third rotating pair, the end platform can complete two rotations and two rotations. Movement of movement.

Claims (5)

1. A non-overconstrained four-degree-of-freedom parallel mechanism with a parallel-series branch comprises a rack, a tail end platform (1), a first middle platform (2), a second middle platform (3), a first revolute pair (4), a second revolute pair (5) and four series branches with the same structure; the first middle platform is connected with the tail end platform through a first revolute pair, and the second middle platform is connected with the tail end platform through a second revolute pair; two series branches are connected between the rack and the first middle platform in parallel, and the other two series branches are connected between the rack and the second middle platform in parallel;

the series branch comprises a mounting seat (6), a third revolute pair (7), a first connecting rod (8), a cross universal joint (9), a first moving pair and a fifth revolute pair (12) which are sequentially connected between the rack and the first middle platform or the second middle platform; the mounting base is fixed on the rack, and the axis of a fifth rotating pair is parallel to the axis of a second rotating shaft of the universal shaft and is vertical to the axis of the first moving pair; or,

the series branch comprises a mounting seat (6), a third revolute pair (7), a first connecting rod (8), a cross universal joint (9), a second connecting rod (13), a fourth revolute pair (14), a third connecting rod (15) and a fifth revolute pair (12) which are sequentially connected between the rack and the first middle platform or the second middle platform; the mounting base is fixed with the rack, and the axes of the fourth rotating pair and the fifth rotating pair are parallel to the second axis of the universal joint.

2. The non-overconstrained four degree-of-freedom parallel mechanism with parallel-parallel branches according to claim 1, wherein: of the four serial branches, two serial branches connected with the first intermediate platform, and the third revolute pair axis intersected with the first axis of the universal joint at one point (O) _A ) (ii) a Two serial branches connecting the second intermediate platform, the third revolute pair axis intersecting 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 parallel-parallel branches of claim 2, wherein: two fifth revolute pair axes, which are connected to the two serial branches of the first intermediate platform, intersect in a common plane; two fifth revolute pair axes are coplanar and intersect in two series branches connected to the second intermediate platform.

4. The non-overconstrained four-degree-of-freedom parallel mechanism with parallel-parallel branches of claim 3, wherein: the first middle platform is connected to the tail end platform through a first rotating pair, and the axis of the first rotating pair is parallel to a plane formed by the axes of the two rotating pairs connected with the first middle platform; the second middle platform is connected to the tail end platform through a second revolute pair, the axis of the second revolute pair is parallel to a plane formed by the axes of two revolute pairs connected with the second middle platform, and the axis of the first revolute pair is parallel to the axis of the second revolute pair.

5. The non-overconstrained four degree-of-freedom parallel mechanism with parallel-series branches according to claim 4, wherein: the first sliding pair is formed by a sleeve (10) and a telescopic rod (11).

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