WO2018170716A1

WO2018170716A1 - Three-degree-of-freedom parallel mechanism having curved prismatic pair

Info

Publication number: WO2018170716A1
Application number: PCT/CN2017/077430
Authority: WO
Inventors: 赵国如; 王永奉
Original assignee: 中国科学院深圳先进技术研究院
Priority date: 2017-03-21
Filing date: 2017-03-21
Publication date: 2018-09-27

Abstract

A three-degree-of-freedom parallel mechanism having curved prismatic pairs, comprising: a base (6), a moving platform (1), a restraining rod (9), and three identical motion branches. The restraining rod (9) is connected to the moving platform (1) and the base (6). The moving platform (1) has a freedom of three rotational directions with respect to the restraining rod (9). The three motion branches are symmetrically disposed around the restraining rod (9); each motion branch comprises a screw assembly and a curved prismatic pair; the screw assembly is disposed on the base (6); the curved prismatic pair is hinged to the moving platform (1); and the curved prismatic pair comprises a lower curved connecting rod (3) and an upper curved connecting rod (2) which are connected in a nested manner. The parallel mechanism is high in flexibility; the motion form of the branches is relatively simple; and the operating precision and quality of the mechanism during operation can be easily ensured.

Description

Three-degree-of-freedom parallel mechanism with curved moving pair

Technical field

The invention relates to the technical field of robot design and manufacture, and in particular relates to a three-degree-of-freedom parallel mechanism with a curved moving pair.

Background technique

The parallel mechanism is usually formed by a plurality of branches connected by the movable platform and the fixed platform. Since the parallel robot was first proposed in 1938, it has large rigidity, strong bearing capacity, small error, high precision, and small self-weight load ratio. It has the characteristics of good dynamic performance and easy control, and is widely used in various fields of society. Currently, there are 2 degrees of freedom, 3 degrees of freedom, 4 degrees of freedom, 6 degrees of freedom parallel robot. Among them, the parallel mechanism with symmetric distribution of symmetrical branches of 3 degrees of freedom is the most studied, and it is applied in the fields of machining rotary platform, rehabilitation equipment, satellite positioning equipment, and installation equipment.

For example, a three-degree-of-freedom spherical parallel mechanism (CN101306534) with a central spherical hinge, which has a typical 3-RRR type mechanism, is proposed by Professor Yan and others of Yanshan University. Achieve three directions of rotation around the fixed center.

Professor Huang Zhen of Yanshan University proposed a parallel mechanism (CN102962840) with a symmetrical structure and no accompanying motion. It can rotate any one of the axes in the middle symmetry plane of the moving platform or any point continuously, which can effectively avoid the occurrence of accompanying motion.

A spherical three-degree-of-freedom parallel mechanism antenna structure system proposed by Shanghai University, Shen Long (CN101924266). Compared with the general three-degree-of-freedom spherical mechanism, it has a larger working space.

A three-degree-of-freedom spherical parallel mechanism (CN104827463) with a curved moving pair proposed by Lin Rongfu and others of Shanghai Jiaotong University. The shape of the curved moving pair is used to realize the rotation of the moving platform at the midpoint of the arc in three directions.

The above-mentioned institutions generally have complicated structures, and there are difficulties in controlling the control precision in the operation process. And other defects.

Summary of the invention

The technical problem to be solved by the present invention is to provide a three-degree-of-freedom parallel mechanism with a curved moving pair which is simple, reliable and easy to control.

In order to solve the above technical problem, a technical solution adopted by the present invention is to provide a three-degree-of-freedom parallel mechanism having a curved moving pair, which comprises a base, a moving platform, a restraining rod and three identical moving branches, and a restraining rod The movable platform and the base are connected, the restraining rod is fixedly arranged with the base, and the movable platform has three degrees of freedom in the rotating direction relative to the restraining rod; the three moving branches are symmetrically arranged around the restraining rod, and each moving branch includes a screw assembly And a curved moving pair, the screw assembly is arranged on the base, the curved moving pair is hinged to the moving platform, and the curved moving pair comprises a nested connecting lower curved connecting rod and an upper curved connecting rod, and the lower curved connecting rod Driven by the screw assembly, linearly move along the axis of the screw assembly and rotate around the axis of the screw assembly, thereby moving the upper curved link along the curved track of the lower curved link and connecting with the lower arc The rods are rotated about the axis of the screw assembly, and one end of the upper curved link is hinged to the moving platform.

Wherein, the screw assembly comprises a motor, a lead screw and a sleeve, the motor is arranged on the base, the screw is connected to the output shaft of the motor, the internal thread of the sleeve is matched with the external thread of the screw, and the lower end of the lower curved link Connect to the casing.

Wherein, the upper curved connecting rod and the moving platform are connected by a cross universal hinge.

Wherein, the lower curved link includes an arc portion and a straight portion connected to each other, the lower end of the straight portion is connected to the sleeve, the curved portion has an empty tubular feature, and the upper curved link is nested into the lower curved link.

Wherein, the lower end of the lower curved connecting rod is connected with the sleeve by a pin shaft.

Wherein, the bottom end of the restraining rod is fixed to the fixed platform, and the top end is connected with the moving platform by the ball joint pair.

The invention has the beneficial effects that the three-degree-of-freedom parallel mechanism of the invention has a curved moving pair, which has three moving branches and one intermediate restraining rod, and the moving branch includes a screw assembly and a curved shape, compared with the prior art. The lower arc-shaped connecting rod of the arc-shaped motion pair is moved along the axis of the screw assembly and rotates around the axis of the screw assembly, and the upper curved connecting rod is along the lower curved connecting rod. Curved track The movement enables the moving platform to achieve three degrees of freedom of rotation. Therefore, the parallel mechanism of the present invention has higher flexibility, and the movement form of the branch is relatively simple, and it is easy to ensure the accuracy and quality of the mechanism during operation.

DRAWINGS

1 is a perspective structural view of a three-degree-of-freedom parallel structure having a curved moving pair according to the present invention;

Figure 2 is a partial structural schematic view of the three-degree-of-freedom parallel mechanism shown in Figure 1;

3 is a schematic structural view of a motion branch of the three-degree-of-freedom parallel mechanism shown in FIG. 1;

Figure 4 is a schematic structural view of the lower curved link of the motion branch of Figure 3;

Figure 5 is a schematic structural view of the upper curved link of the motion branch shown in Figure 3;

Figure 6 is a schematic structural view of the sleeve of the motion branch shown in Figure 3;

Figure 7 is a schematic view showing the structure of the screw of the motion branch shown in Figure 3.

detailed description

Referring to Figures 1 and 2, the three-degree-of-freedom parallel mechanism of the present invention having a curved moving pair includes a base 6, a moving platform 1, a restraining rod 9, and three identical moving branches (not labeled).

The restraining rod 9 is connected to the movable platform 1 and the base 6, and the restraining rod 9 is fixedly disposed with the base 6, and the movable platform 1 has three degrees of freedom with respect to the restraining rod 9. Specifically, the restraining rod 9 has an elongated shape, and the bottom end thereof is fixedly disposed on the base 6 and extends in a direction perpendicular to the reference surface of the base 6, and the top end is connected to the movable platform 1 by the ball joint pair 11.

The three motion branches are symmetrically arranged around the restraining rod 9. The meaning of center symmetry is: the fixed point of each moving branch connected to the base 6 is equal to the distance of the restraining rod 9, and the angle between the fixed point of the two adjacent moving branches to the vertical line of the restraining rod is 120°; And the hinge point of each moving branch connected to the moving platform 1 is equal to the distance of the restraining rod 9, and the angle between the hinge point of the two adjacent moving branches to the vertical connecting line of the restraining rod is also 120 degrees.

With further reference to Figures 3 through 7, each of the motion branches includes a screw assembly (not labeled) and an arc. Sports officer (not shown). The lead screw assembly is disposed on the base 6, and the curved motion pair is hinged to the movable platform 1. The curved motion pair includes a nested lower arch link 3 and an upper curved link 2, and the upper curved link 2 and the lower curved link 3 are centered. The lower curved connecting rod 3 linearly moves along the axis direction of the screw assembly and rotates around the axis of the screw assembly under the driving of the screw assembly, so that the upper curved connecting rod 2 is curved along the lower curved connecting rod 3 The track moves and rotates about the axis of the screw assembly with the lower curved link 3, and one end of the upper curved link 2 is hinged to the movable platform 1.

Specifically, the lead screw assembly includes a motor 7, a lead screw 5, and a sleeve 4. The motor 7 is disposed on the base 6, the lead screw 5 is connected to the output shaft of the motor 7, the internal thread 15 of the sleeve 4 is engaged with the external thread 17 of the lead screw 5, and the lower end 12 of the lower curved link 3 is connected to the sleeve 4. The fixed position of the motor 7 on the base 6 is the aforementioned fixed point.

In this embodiment, the hole 16 of the upper end of the sleeve 4 (the end opposite to the internal thread) and the lower end 12 of the lower curved link 3 are connected by a pin so that the lower curved link 3 can be wound around the screw assembly. The sleeve 4 is rotated in the axial direction.

In this embodiment, the lower curved link of the curved moving pair includes an arcuate portion and a straight portion connected to each other, and the lower end 12 of the straight portion is connected to the sleeve 4, and the curved portion has an empty tubular feature 13 and an upper curved joint The rod 2 is nested into the curved portion of the lower curved link 3. In practical applications, an empty tubular feature may also be provided on the upper curved link 2, and the curved portion of the lower curved link 3 is nested into the upper curved link 2. Alternatively, one of the upper curved link 2 and the lower curved link 3 is provided with an arcuate chute, and the other is provided with an arcuate slide or the like. Whether it is a fully covered hollow tubular feature or a partially covered curved chute and slide arrangement, the nested connection of the curved track movement of the curved link 2 with respect to the lower curved link 3 is included in the present invention. In the range.

In this embodiment, the upper curved link 2 and the movable platform 1 are connected by a cross universal hinge. Specifically, the top end of the upper curved connecting rod 2 is provided with a hole 14 , one end of the cross universal hinge 10 is fixed into the hole 14 , and the other end is fixed to the movable platform 1 , and the position of the cross universal joint 10 on the moving platform 1 is set. That is, the aforementioned hinge point.

In the motion branch of the embodiment, the motor 7 drives the lead screw 5 to rotate, and the screw 5 rotates into a linear motion of the sleeve 4 along the axial direction of the lead screw 5, thereby driving the lower curved connecting rod 3 along the screw assembly. of Moving in the axial direction, in the process of linear movement of the lower curved link 3 along the axial direction of the screw assembly, the lower curved link 3 can also rotate about the axis of the screw assembly, and the upper curved link 2 can be caused Moving along the curved track of the lower curved link 3, the upper end of the upper curved link 2 is connected to the movable platform 1 by the cross universal joint 10, so that the movable platform 1 has three degrees of freedom in the direction of rotation.

Different from the prior art, the present invention has a three-degree-of-freedom parallel mechanism with a curved moving pair having three moving branches and an intermediate restraining rod 9. The moving branch includes a screw assembly and a curved motion pair, and the curved motion pair The lower curved connecting rod 3 is moved along the axis of the screw assembly and rotates around the axis of the screw assembly under the driving of the screw assembly, and the upper curved connecting rod 2 is along the curved track of the lower curved connecting rod 3. The movement causes the moving platform 1 to achieve three degrees of freedom of rotation. Therefore, the parallel mechanism of the present invention has higher flexibility, and the movement form of the branch is relatively simple, and it is easy to ensure the accuracy and quality of the mechanism during operation.

The above is only the embodiment of the present invention, and is not intended to limit the scope of the invention, and the equivalent structure or equivalent process transformations made by the description of the invention and the drawings are directly or indirectly applied to other related technologies. The fields are all included in the scope of patent protection of the present invention.

Claims

A three-degree-of-freedom parallel mechanism with a curved moving pair, characterized in that the three-degree-of-freedom parallel mechanism comprises a base, a moving platform, a restraining rod and three identical moving branches,

The restraining rod connects the moving platform and the base, the restraining rod is fixedly disposed with the base, and the moving platform has three degrees of freedom with respect to the restraining rod;

The three motion branches are symmetrically disposed about the constraint bar, each of the motion branches includes a screw assembly and a curved movement pair, and the screw assembly is disposed on the base, the arc a moving pair hinged to the moving platform, the curved moving pair comprising a nested lower curved connecting rod and an upper curved connecting rod, the lower curved connecting rod being driven by the lead screw assembly Actuating the axial direction of the screw assembly linearly and rotating about the axis of the lead screw assembly, thereby moving the upper curved link along the curved track of the lower curved link and the lower arc The links rotate together about the axis of the lead screw assembly, one end of the upper curved link being hinged to the moving platform.
The three-degree-of-freedom parallel mechanism according to claim 1, wherein the lead screw assembly comprises a motor, a lead screw and a sleeve, the motor is disposed on the base, and the lead screw is connected to the An output shaft of the motor, an internal thread of the sleeve mates with an external thread of the lead screw, and a lower end of the lower curved link is coupled to the sleeve.
The three-degree-of-freedom parallel mechanism according to claim 2, wherein the upper curved link and the movable platform are connected by a cross universal hinge.
The three-degree-of-freedom parallel mechanism according to claim 2, wherein the lower curved link includes an arcuate portion and a straight portion that are connected to each other, and a lower end of the straight portion is connected to the sleeve, The curved portion has an empty tubular feature, and the upper curved link is nested into the lower curved link.
The three-degree-of-freedom parallel mechanism according to claim 2, wherein the lower end of the lower curved link is connected to the sleeve by a pin.
The three-degree-of-freedom parallel mechanism according to claim 1, wherein a bottom end of the restraining rod is fixed to the fixed platform, and a top end is connected to the moving platform by a ball joint pair.