CN102240911A - Incompletely-symmetrical four-freedom-degree space in-parallel mechanism with two-dimensional rotation and two-dimensional movement - Google Patents

Abstract

A non-completely symmetrical four-degree-of-freedom space parallel mechanism with two-dimensional rotation and two-dimensional movement, including a fixed platform and a moving platform. Four branches are connected between the fixed platform and the moving platform. The connection and combination of the first branch and the third branch are the same. The platform is connected to the moving platform; the connection and combination of the second branch and the fourth branch are the same, and the fixed platform and the moving platform are connected by the first rotating pair, the universal joint and the ball joint between the rods in turn. ; The bottom of the moving platform is equipped with a detachable motor that can drive the moving platform to rotate vertically. The advantages of the present invention are: 1. The structure is simple and compact, which is convenient for manufacture and installation. 2. There are few types of components, simple assembly, and the driving device is simple and easy to control. 3. The overall moment of inertia is small, and the dynamic motion characteristics are good. 4. The movable platform can have the output of two-dimensional movement and two-dimensional rotation.

Description

A non-completely symmetrical four-degree-of-freedom space parallel mechanism with two-dimensional rotation and two-dimensional movement

Technical field:

The invention belongs to the field of parallel mechanisms, in particular to a non-completely symmetrical four-degree-of-freedom space parallel mechanism with two-dimensional rotation and two-dimensional movement.

Background technique:

With the rise of parallel mechanism science, the application range of parallel mechanism in the fields of CNC machine tools, robots, and medical surgery is becoming wider and wider. The main reason is that the parallel mechanism has high advantages such as compactness. At present, the degrees of freedom of the most widely used parallel mechanisms are three degrees of freedom or six degrees of freedom. There are few parallel mechanisms with four degrees of freedom studied and applied, and most of the published four degrees of freedom parallel mechanisms realize three-dimensional translation and One-dimensional rotation, four-degree-of-freedom parallel mechanisms that realize two-dimensional rotation and two-dimensional movement are very few. Most of the drive devices use the moving pairs in each branch chain, which increases the transmission conversion device and reduces the rigidity of the overall mechanism, and the drive motor is installed on each branch chain, which increases the moment of inertia of the overall mechanism.

Invention content:

The object of the present invention is to design a non-completely symmetrical four-degree-of-freedom space parallel mechanism with two-dimensional rotation and two-dimensional movement. The problems existing in the existing four-degree-of-freedom parallel mechanism.

As conceived above, the technical solution of the present invention is: a non-completely symmetrical four-degree-of-freedom space parallel mechanism with two-dimensional rotation and two-dimensional movement, including a fixed platform and a moving platform, characterized in that: between the fixed platform and the moving platform Four branches are connected, the first branch and the third branch are connected in the same way, and the fixed platform and the moving platform are connected by the first rotating pair, the second rotating pair and the ball joint between the rods in turn; The connection and combination of the second branch and the fourth branch are the same, and the fixed platform and the moving platform are connected through the first rotating pair, the universal joint and the ball joint in turn between each rod; the bottom of the moving platform is equipped with a movable A detachable motor that drives the movable platform to rotate vertically.

The above-mentioned first and third branches are constrained branches, both of which are connected by upper and lower connecting rods. One end of the lower connecting rod is connected with the fixed platform through the first rotating pair, and the other end is connected through the second The rotary pair is connected with one end of the upper link, and the other end of the upper link is connected with the moving platform through a ball joint.

The second branch and the fourth branch mentioned above are unconstrained branches, both of which are connected by upper and lower connecting rods. One end of the lower connecting rod is connected with the fixed platform through a rotating pair, and the other end is connected through a universal hinge. It is connected with one end of the upper link, and the other end of the upper link is connected with the moving platform through a ball joint.

The above second branch and the fourth branch are symmetrical about the plane composed of the first branch and the third branch; the first branch and the third branch are about the second branch and the fourth branch The plane composed of branches is symmetrical.

Among the above four branches, the four first revolving pairs serving as the driving devices of the entire mechanism are evenly distributed around the fixed platform, and are respectively connected with the four driving motors.

The axis (1a, 1b) of the revolving pair in the first branch above and the axis (3a, 3b) of the revolving pair in the third branch are parallel to each other; the axis (2a) of the revolving pair in the second branch and the The axes (4a) of the rotary pairs in the four branches are parallel to each other and orthogonal to the axes of the rotary pairs in the first and third branches.

The axis (2b) of the universal joint in the above-mentioned second branch is orthogonal to the axis of the rotating pair (2a) and another axis (2c) of the universal joint respectively; the axis (4b) of the universal joint in the fourth branch ) are respectively perpendicular to the rotary axis (4a) and the other axis (4c) of the universal joint.

The ball joints connecting the above four branches to the moving platform are replaced by three equivalent rotating pairs, wherein one axis of the ball joint is parallel to the axis of the connecting rods of each branch; one axis of the ball joint is in the plane of the moving platform, And evenly distributed on the four peripheries of the moving platform; the other axis of the ball hinge is respectively perpendicular to the plane formed by the first two axes.

A tool clamping device is installed on the above moving platform.

The present invention has following advantage and positive effect:

1. Simple and compact structure, easy to manufacture and install.

2. The present invention has few types of components, simple assembly, simple driving device and easy control.

3. The overall moment of inertia of the present invention is small, and the dynamic motion characteristics are good.

4. The present invention can make the movable platform have two-dimensional movement and two-dimensional rotation output. If necessary, cooperate with the lower end of the moving platform

The detachable motor on the surface increases the one-dimensional rotation output of the cutter on the moving platform.

Description of drawings

Fig. 1 is the three-dimensional isometric side view of parallel mechanism of the present invention;

Fig. 2 is the front view of parallel mechanism of the present invention;

Fig. 3 is a side view of the parallel mechanism of the present invention.

In the figure: 1. The first branch, 2. The second branch, 3. The third branch, 4. The fourth branch, 5. The moving platform, 6. The tool clamping device, 7. Can Select the motor, 8. Fixed platform, A. Universal hinge, C. Equivalent spherical hinge, 11. The lower link of the first branch, 12. The upper link of the first branch, 21. The second The lower link of the branch, 22. The upper link of the second branch, 31. The lower link of the third branch, 32. The upper link of the third branch, 41. The fourth branch 42. The upper link of the fourth branch, 1a. the axis of the first rotating pair of branch chain one, 2a. the axis of the rotating pair of branch chain two, 3a. the first rotating pair of branch chain three Axis, 4a. Rotating pair axis of branch chain 4, 1b. Second rotating pair axis of branch chain 1, 2b. First axis of branch chain 2 universal hinge, 3b. Second rotating pair axis of branch chain 3, 4b . The first axis of the four universal hinges of the branch chain, 2c. The second axis of the two universal hinges of the branch chain, 4c the second axis of the four universal hinges of the branch chain.

Detailed ways

The present invention will be explained in detail below in conjunction with the accompanying drawings and specific embodiments.

As shown in Figure 1, a non-completely symmetrical four-degree-of-freedom space parallel mechanism with two-dimensional rotation and two-dimensional movement of the present invention includes a fixed platform (8) and a moving platform (5), connecting the fixed platform and the moving platform The first branch (1), the second branch (2), the third branch (3), the fourth branch (4), the tool clamping device installed on the upper end of the moving platform (6 ) and a detachable motor (7) installed on the lower surface of the moving platform. The first branch (1) and the third branch (3) have the same connection mode; the second branch (2) and the fourth branch (4) have the same connection Way. The second branch (2) and the fourth branch (4) are symmetrical about the plane composed of the first branch (1) and the third branch (3); the first branch (1) and the The three branches (3) are symmetrical about the plane formed by the second branch (2) and the fourth branch (4).

In this mechanism, one end of the connecting rod (11) in the first branch (1) is connected with the fixed platform (8) through the first rotating pair; the other end is connected with the connecting rod (12) through the second rotating pair, and the two The axes (1a, 1b) of the rotating pair are parallel to each other; the other end of the connecting rod (12) is connected to the moving platform (5) through a ball joint (C), and the ball joint is replaced by three equivalent moving pairs, among which the ball joint An axis of the pair is along the axial direction of the connecting rod (12), and an axis of the ball joint is in the plane of the moving platform (5) and parallel to a periphery of the moving platform (5).

In this mechanism, one end of the connecting rod (21) in the second branch (2) is connected with the fixed platform (8) through a rotating pair; the other end is connected with the connecting rod (22) through a universal hinge, and the The axis (2b) is perpendicular to the axis of the rotary joint (2a), and the axis (2c) of the universal joint is perpendicular to the axis (2b) of the universal joint; the other end of the connecting rod (22) passes through the ball joint (C) and the dynamic The platform (5) is connected, and the ball joint pair is replaced by three equivalent moving pairs, wherein one axis of the ball joint pair is along the axial direction of the connecting rod (22), and one axis of the ball joint pair is on the moving platform (5). In the plane and parallel to a perimeter of the moving platform (5).

In this mechanism, the driving devices of each branch are installed on the fixed frame, and the rotation angle of each branch relative to the fixed platform (8) is adjusted by the rotation angle of the first rotating pair in each branch relative to the fixed platform (8). position, and then change the pose of the moving platform (5).

In this embodiment, a servo drive motor is used for driving, but other types of motors may also be used for driving.

The working principle of this mechanism is as follows: Since the second branch and the fourth branch are non-constrained branches, they have no restraint effect on the mechanism, while the first branch and the third branch are constrained branches, which work together to provide the whole mechanism Two constraints (rotation perpendicular to the moving platform and movement in the direction of the axis of rotation of the first and third branch chains) are established, so that the moving platform has two-dimensional rotation and two-dimensional movement output. Adjust the pose of the moving platform by adjusting the output parameters of the servo motor.

Claims (9)

1. A non-completely symmetrical four-degree-of-freedom space parallel mechanism with two-dimensional rotation and two-dimensional movement, comprising a fixed platform and a moving platform, characterized in that four branches are connected between the fixed platform and the moving platform, the first The connection and combination of the branch road and the third branch road are the same, and the fixed platform and the moving platform are connected by the first rotating pair, the second rotating pair and the ball joint in sequence between the rods; the second branch road and the fourth branch road The connection and combination of the branch roads are the same, and the fixed platform and the moving platform are connected by the first rotating pair, the universal joint and the ball joint in turn between the rods; the bottom of the moving platform is equipped with a removable motor. 2. A non-completely symmetrical four-degree-of-freedom space parallel mechanism with two-dimensional rotation and two-dimensional movement according to claim 1, characterized in that: the first branch and the third branch are constrained branches Both are composed of upper and lower connecting rods, one end of the lower connecting rod is connected with the fixed platform through the first rotating pair, the other end is connected with one end of the upper connecting rod through the second rotating pair, and the other end of the upper connecting rod One end is connected with the moving platform through a ball hinge. 3. A non-completely symmetrical four-degree-of-freedom space parallel mechanism with two-dimensional rotation and two-dimensional movement according to claim 1, characterized in that: the second branch and the fourth branch are non-constrained The branches are composed of upper and lower connecting rods, one end of the lower connecting rod is connected with the fixed platform through a rotating pair, the other end is connected with one end of the upper connecting rod through a universal hinge, and the other end of the upper connecting rod is connected through The ball hinge is connected with the moving platform. 4. A non-completely symmetrical four-degree-of-freedom space parallel mechanism with two-dimensional rotation and two-dimensional movement according to claim 1, 2 or 3, characterized in that: the second branch and the fourth branch The road is symmetrical about the plane formed by the first branch and the third branch; the first branch and the third branch are symmetrical about the plane formed by the second branch and the fourth branch. 5. A non-completely symmetrical four-degree-of-freedom space parallel mechanism with two-dimensional rotation and two-dimensional movement according to claim 1, 2 or 3, characterized in that: four of the four branches as the driving device of the entire mechanism A first rotating pair is evenly distributed around the fixed platform and connected with four drive motors respectively. 6. A non-completely symmetrical four-degree-of-freedom space parallel mechanism with two-dimensional rotation and two-dimensional movement according to claim 1, 2 or 3, characterized in that: the axis of the rotating pair in the first branch ( 1a, 1b) and the axis of the revolving pair in the third branch (3a, 3b) are parallel to each other; the axis of the revolving pair in the second branch (2a) and the axis of the revolving pair in the fourth branch (4a) They are parallel to each other and perpendicular to the axis of rotation of the first and third branches. 7. A non-completely symmetrical four-degree-of-freedom space parallel mechanism with two-dimensional rotation and two-dimensional movement according to claim 1, 2 or 3, characterized in that: the axis of the universal joint in the second branch (2b) are respectively perpendicular to the rotary axis (2a) and the other axis (2c) of the universal hinge; the axis (4b) of the universal hinge in the fourth branch is respectively perpendicular to the rotary axis (4a) and the The other axis (4c) of the hinge is orthogonal. 8. A non-completely symmetrical four-degree-of-freedom space parallel mechanism with two-dimensional rotation and two-dimensional movement according to claim 1, 2 or 3, characterized in that: the four branches are used for ball joints connected to the moving platform Three equivalent rotating pairs are used instead, wherein one axis of the ball joint is parallel to the axis of each branch connecting rod; one axis of the ball joint is in the plane of the moving platform and evenly distributed on the four peripheries of the moving platform; The other axes of the ball hinge are respectively perpendicular to the plane formed by the respective first two axes. 9. A non-completely symmetrical four-degree-of-freedom space parallel mechanism with two-dimensional rotation and two-dimensional movement according to claim 1, wherein a tool clamping device is installed on the moving platform.

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