WO2018195769A1

WO2018195769A1 - Three-degrees-of-freedom parallel mechanism having an arc-shaped movement pair

Info

Publication number: WO2018195769A1
Application number: PCT/CN2017/081835
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: 2017-04-25
Filing date: 2017-04-25
Publication date: 2018-11-01

Abstract

Provided is a three-degrees-of-freedom parallel mechanism having an arc-shaped movement pair, the mechanism comprising a fixed platform (110), a movable platform (120) and three arc-shaped support linkages (130) provided between the fixed platform (110) and the movable platform (120). Each of the arc-shaped support linkages (130) comprises a first arc-shaped connecting rod (132) and a second arc-shaped connecting rod (134) sharing the same arc centre. One end of the first arc-shaped connecting rod (132) is connected to the fixed platform (110) using a revolute pair (136). One end of the second arc-shaped connecting rod (134) is provided in a cavity of the other end of the first arc-shaped connecting rod (132), and the second arc-shaped connecting rod (134) can perform a reciprocating motion in a tangential direction of a circular arc of the first arc-shaped connecting rod (132). The other end of the second arc-shaped connecting rod (134) is connected to the movable platform (120) using a ball joint (138). The three revolute pairs (136) of the three arc-shaped support linkages (130) are uniformly distributed on a circumference of the fixed platform (110) at intervals. The axial directions of the revolute pairs (136) are parallel to each other, and a rotation centre of the movable platform of the parallel mechanism is a point of intersection of lines for connecting the centres of the ball joints (138) of the arc-shaped support linkages (130) and the arc centres of the arc-shaped support linkages (130). The point of intersection changes with the pose of the movable platform, and therefore, the movable platform has a relatively large work space, a simple and reliable structure, and a high flexibility.

Description

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

Technical field

The invention relates to the technical field of parallel mechanisms, in particular to a three-degree-of-freedom parallel mechanism with curved moving pairs.

Background technique

Since the parallel robot was first proposed in 1938, it has been widely used in various fields of society because of its large rigidity, strong bearing capacity, small error, high precision, small self-weight load ratio, good dynamic performance and easy control. At present, there are 2 degrees of freedom, 3 degrees of freedom, 4 degrees of freedom, 6 degrees of freedom parallel mechanism; currently, the three degree of freedom parallel mechanism is the most researched and widely used type of less freedom parallel mechanism. It can be divided into four categories according to the type of platform freedom: 3 rotating parallel mechanism, 2 rotating 1 moving parallel mechanism, 1 rotating 2 moving parallel mechanism, 3 moving parallel mechanism. Among them, the spherical parallel mechanism belongs to a 3-rotation parallel mechanism, which can realize the arbitrary rotation of the spherical center of the spherical surface around the reference point of the moving platform. When the mechanism moves, all the points on the moving platform of the mechanism are around the spherical center and fixed by one. The radius rotates. The advantage of spherical parallel connection with respect to the general parallel mechanism is that the working space is large, flexible and reliable, and it is not easy to interfere.

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.

Most of the motion sub-configurations of these institutional branches include RR or RRR, and the axes of these motion pairs intersect at one point to achieve the three degrees of freedom of the moving platform. Among them, Shanghai Jiaotong University Lin Rongfu uses curved moving pairs to make the movement The arc configuration of the pair allows the moving platform to be constrained by forces in three directions, and can only rotate in three directions around the center of the arc, and its center of rotation is fixed, resulting in a small working space.

Summary of the invention

In view of this, it is necessary to provide a three-degree-of-freedom parallel mechanism having a curved working pair with a large working space.

A three-degree-of-freedom parallel mechanism with a curved moving pair, comprising a fixed platform, a moving platform, and three curved branches disposed between the fixed platform and the moving platform;

Each of the curved branches includes a first curved link and a second curved link of a common arc center, and one end of the first curved rod and the fixed platform are connected by a rotating pair, the second One end of the curved rod is disposed in a cavity at the other end of the first curved rod, and the second curved rod is reciprocable along a tangential direction of an arc of the first curved rod, The other end of the second curved rod and the moving platform are connected by a ball joint, and the three rotating pairs of the three curved branches are evenly spaced on the circumference of the fixed platform.

In one of the embodiments, the axes of the three said rotating pairs are parallel to each other.

In one embodiment, the cavity of the first curved rod has a circular, elliptical or square cross section.

In one of the embodiments, the three curved branches have the same radius.

In one of the embodiments, the three curved branches have different radii.

The above-mentioned three-degree-of-freedom parallel mechanism having a curved moving pair, one end of the curved branch is connected by the rotating pair and the fixed platform, and the other end of the curved branch is connected by the ball joint and the movable platform, and the axes of the rotating pair are mutually Parallel configuration, and the center of rotation of the parallel mechanism moving platform is the intersection of the center of each curved branch ball joint and the center of the curved branch, and the intersection changes with the posture of the moving platform, thereby making the working space of the moving platform Larger. The structure is simple and reliable, the driving ability is strong, the flexibility is high, and the moving platform is stable, and can be applied to the fields of virtual axis machine tools, industrial robots, aviation simulation equipment, medical equipment and the like.

DRAWINGS

1 is a schematic structural view of a three-degree-of-freedom parallel mechanism having a curved moving pair according to an embodiment;

2 is a schematic view showing the center of rotation of the above-described three-degree-of-freedom parallel mechanism having a curved moving pair. In the figure, O1, O2, and O3 are arc centers of three curved branches, respectively, and O is a center of rotation.

detailed description

In order to make the objects, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Referring to FIG. 1 , a three-degree-of-freedom parallel mechanism 100 having a curved moving pair includes a fixed platform 110 , a moving platform 120 , and three curved branches disposed between the fixed platform 110 and the moving platform 120 . 130.

Referring also to FIG. 2, each of the arcuate branches 130 includes a first arcuate link 132 and a second arcuate link 134 that are coaxial. One end of the first curved rod 132 and the fixed platform 110 are connected by a rotating pair 136. One end of the second curved rod 134 is disposed in the cavity at the other end of the first curved rod 132, and the second curved rod 134 is reciprocable along the tangential direction of the circular arc of the first curved rod 132. The other end of the second curved rod 134 and the movable platform 120 are connected by a ball joint 138.

In the present embodiment, the fixed platform 110 is configured as a circular plate. It can be understood that the structure of the fixed platform 110 is designed into a square plate, a rectangular plate and the like according to requirements. The structure of the movable platform 120 is a triangular plate. The three vertices of the triangular plate are respectively connected to one end of the fixed platform 110 by three ball joints 138 and three curved branches 130.

The three rotating pairs 136 of the three curved branches 130 are evenly spaced on the circumference of the fixed platform 110. That is, the connection of the three rotating pairs 136 on the fixed platform 110 is an isosceles triangle. The three curved branches 130 are symmetrically distributed between the fixed platform 110 and the movable platform 120 on a circumference parallel to the fixed platform 110.

The axes of the three rotating pairs 136 are parallel to each other. The axes of the three rotating pairs 136 are perpendicular to the fixed platform 110 and point toward the arc of the curved branch 130.

The first curved rod 132 can be a curved tubular structure. The cross section of the cavity of the first curved rod 132 may be a circular, elliptical or square structure. The cross section of the second curved link 134 may be a circular, elliptical or square structure that matches the cavity structure of the first curved rod 132.

The second curved rod 134 can reciprocate along the tangential direction of the arc of the first curved rod 132, that is, the second curved rod 134 can enter or extend the first curved rod 132, thereby adjusting the movable platform 120 and fixing The distance between the platforms 110.

The radii of the three curved branches 130 can be designed to be the same or different depending on the requirements of the different workspaces or flexibility.

The three-degree-of-freedom parallel mechanism 100 having a curved moving pair realizes the movable platform 120 around the three curved branches 130 by driving the rotation angle of the first curved rod 132 on the fixed platform 110 about the axis of the rotating pair 136. The intersection of the centers of the respective ball joints and the arc-centers of the respective arc-shaped branches 130 is rotated in three directions of the axis of the three-dimensional coordinate system. That is, referring to FIG. 2, the center of rotation of the movable platform 110 of the three-degree-of-freedom parallel mechanism 100 having the curved moving pair is the center of the ball joint 138 of each curved branch 130 and the arc of the curved branch 130. The intersection of the line, which changes with the posture of the platform 120. The three-degree-of-freedom parallel mechanism 100 having the curved moving pair has one end of each of the three curved branches 130 directly connected to the fixed platform 110, so that the rotating center of the parallel mechanism 100 is not fixed, and can be arbitrarily configured according to actual requirements. The curved branch is installed at the fixed platform, which has no limitations on the installation requirements, improving its working space and flexibility.

The three-degree-of-freedom parallel mechanism 100 having the curved moving pair has one end connected to the fixed platform 110 through the rotating pair 136, and the other end of the curved branch 130 is connected to the moving platform 120 through the ball hinge 138, and rotates The axes of the pair 136 are arranged parallel to each other, and the center of rotation of the parallel mechanism moving platform 120 It is the intersection of the center of the arc-shaped branch 130 and the center of the arc-shaped branch 130. The intersection changes with the posture of the platform 120, so that the working space of the movable platform 120 is large. The structure is simple and reliable, the driving ability is strong, the flexibility is high, and the moving platform 120 is stable in motion, and can be applied to the fields of virtual axis machine tools, industrial robots, aviation simulation equipment, medical equipment and the like.

The above is only a preferred embodiment of the present invention, and it should be noted that those skilled in the art can also make several improvements and refinements without departing from the principles of the present invention. These improvements and retouchings should also be regarded as The scope of protection of the invention.

Claims

A three-degree-of-freedom parallel mechanism having a curved moving pair, comprising: a fixed platform, a moving platform, and three curved branches disposed between the fixed platform and the moving platform;

Each of the curved branches includes a first curved link and a second curved link of a common arc center, and one end of the first curved rod and the fixed platform are connected by a rotating pair, the second One end of the curved rod is disposed in a cavity at the other end of the first curved rod, and the second curved rod is reciprocable along a tangential direction of an arc of the first curved rod, The other end of the second curved rod and the moving platform are connected by a ball joint, and the three rotating pairs of the three curved branches are evenly spaced on the circumference of the fixed platform.
A three-degree-of-freedom parallel mechanism having a curved moving pair according to claim 1, wherein the axes of the three rotating pairs are parallel to each other.
A three-degree-of-freedom parallel mechanism having a curved moving pair according to claim 1, wherein the cavity of the first curved rod has a circular, elliptical or square cross section.
A three-degree-of-freedom parallel mechanism having a curved moving pair according to claim 1, wherein the three said curved branches have the same radius.
A three-degree-of-freedom parallel mechanism having a curved moving pair according to claim 1, wherein the three said curved branches have different radii.