CN1857875A - Three-translation and one-rotation parallel mechanism - Google Patents

Abstract

A three-translation-rotation parallel mechanism, which is composed of a static platform (1), a moving platform (12) and four kinematic branch chains; the swing control arms (3) of the first and third branch chains pass through the rotating pair (2), ( 4) It is connected with the static platform (1) and the parallelogram hinge (6), and the parallelogram hinge (6) is connected with the moving platform (12) through the rotating pair (7); the swing control arms (3) of the second and fourth branches Respectively connected to the rotating pair (2), (4); the rotation axis of the rotating pair (1) connected to the static platform by the four branch chains is arranged on the plane xoy; the rotating pair (2) of the second and four branch chains , (4) and the moving platform (12) have increased the connecting frame rod (8) and the rotating pair (9); the connecting frame rod (8) connects the rotating pair (7) and connects the moving platform ( 12) Linking: the axes of the rotating pairs (9) of the second and fourth branch chains are perpendicular to the axes of the rotating pairs (7) of the respective branch chains, and the arrangement of the axes can be coaxial or non-axial.

Description

Three-translation-rotation parallel mechanism

technical field

The invention relates to a new three-translation, one-rotation four-degree-of-freedom parallel mechanism, which can be used as a motion actuator for industrial robots and parallel machine tools. It belongs to the technical field of robot technology and numerical control processing equipment.

Background technique

The Delta parallel robot was first proposed and patented by Clavel of the Swiss Institute of Technology in Lausanne (EPFL). Please refer to shown in Fig. 1, the structure of this mechanism is made of static platform 1, dynamic platform 12 and three kinematic branch chains connecting dynamic 1, static platform 12. The rotation axes of the rotating pair 2 whose three branch chains are connected to the static platform are symmetrically arranged on the plane of the static platform, and the structures of the three moving branch chains are exactly the same. Every branch chain is made up of revolving pairs 2, 4, 5, 7, swing control arm 3, parallelogram four-bar linkage mechanism-parallelogram hinge 6 connection. The swing control arm 3 is connected to the static platform 1 and the parallelogram hinge 6 through the swivel pair 2 and the swivel pair 4 respectively, and the parallelogram hinge 6 is connected to the moving platform 12 through the swivel pair 7 . Parallelogram hinge 6 is a parallelogram closed four-bar linkage mechanism formed by two long and two short pairs of connecting rods (the lengths of each pair of rods are respectively equal) through the rotating pair 5, and the axis of the rotating pair 5 is perpendicular to the four connecting rods. The quadrilateral plane, as shown in Figure 3A; four connecting rods can also be connected by two revolving joints and two ball joints. The included angle between the long link and the short link in the parallelogram hinge 6 can vary, as shown in FIG. 3B ; but the long links and the short links are always kept parallel to each other. The revolving pair 4, 7 is placed in the middle of the short connecting rod of the parallelogram hinge 5. The working principle of the Delta parallel robot is: the motor or other drivers drive the swing control arm 2 to repeatedly swing at a certain angle, and then drive the parallelogram hinge 6 to move. Three parallelogram hinges 6 open and close, translation and rotation motion drive the moving platform 12 to realize translation motion in three coordinate directions. The working end of the robot is fixed on the moving platform 12, and the parts on the working end can be manipulated by the motor on the static platform 1 through the mechanism in the telescopic sleeve. The characteristics of this parallel robot are: the moving parts are light, the acceleration can be as high as 12g, and it is suitable for handling objects with a small mass (1g~1kg) within the working range of 1000mm in diameter and 200mm in height. The Swiss company Demaurex purchased the patent in 1987 and commercialized it, and developed a series of products such as Pack-Placer and Line-Placer. In recent years, Sweden's ABB Group and Japan's Nichili Seiki have also launched new pick-and-place robots and high-speed drilling machines based on Delta robots. At present, Delta parallel robots have been widely used in cosmetics, food and pharmaceutical packaging and electronic product assembly and other fields.

Due to the simple structure, light weight and reasonable design of the motion structure of the moving parts of the Delta robot, the Delta robot has the outstanding advantage of fast acceleration. However, the moving platform of the Delta robot can only realize translational movement in three coordinate directions, and cannot realize rotational movement. If a mechanism not only has the above-mentioned advantages of the Delta robot, but also has a rotating motion on the moving platform, then the movement of the working end on the moving platform will be more flexible, and this mechanism can adapt to more workplaces and meet a wider range of requirements.

Based on the advantages and disadvantages of the above-mentioned Delta robot, Francois Pierrot et al. published a paper "H4: a new family of 4-dof parallel robots" at the 1999 IEEE/ASME International Conference and proposed a new type of mechanism: the structure of the H4 robot is shown in the figure As shown in 2, this mechanism has four kinematic chains with the same structure as the kinematic branch chain in the Delta mechanism connected between the upper static platform and the lower dynamic platform. These four kinematic chains are not directly connected on the moving platform, but every two kinematic chains are connected to the link rod 10 . The link frame 10 is connected to the moving platform through the rotary joint 11. The rotation axes of the two rotary pairs 11 are perpendicular to the plane of the moving platform. The moving platform of the H4 mechanism has translational movement along three directions and rotational movement around the rotation axis perpendicular to the plane of the static platform.

Contents of the invention

The purpose of the present invention is: in order to overcome the limitation that the Delta robot can only move in translation, design the present invention-a four-degree-of-freedom, high-speed movement, parallel connection of a Delta robot that can be used for industrial robots and CNC machine tool motion actuators mechanism.

The present invention is realized by adopting the following technical means:

A three-translation-rotation parallel mechanism, consisting of a static platform (1), a moving platform (12) and four motion branch chains; the four motion branch chains are arranged around the static platform, wherein the first and third branch chains The swing control arm (3) is respectively connected with the static platform (1) and the parallelogram hinge (6) through the swivel pair (2), (4), and the parallelogram hinge (6) is connected with the moving platform (12) through the swivel pair (7). ) are connected; the swing control arms (3) of the second and fourth branch chains are respectively connected to the rotating joints (2), (4); the geometric center position of the static platform establishes a coordinate system o-xyz, and the x-axis points to the third branch chain At the center position of the rotating pair (2), the y-axis points to the center position of the second branch chain rotating pair (2), the z-axis is determined by the right-hand rule, and the rotation axis of the rotating pair (1) connecting the four branch chains with the static platform Arranged on the plane xoy; the connecting frame rod (8) and the rotating pair (9) are added between the rotating pairs (2), (4) and the moving platform (12) of the second and fourth branch chains; the connecting frame The rod (8) is connected to the rotating pair (7) and is connected to the moving platform (12) through the rotating pair (9): one end of the four branch chains is connected to the static platform (1) by the swing control arm (3), and the swing control arm (3) ) is connected to the parallelogram hinge (6), and the other end of the branch chain is connected to the moving platform (12) by the parallelogram hinge (6) on the first and third branch chains through the rotating pair (7). The parallelogram hinge (6) on the chain connects the connecting frame rod (8), and the connecting frame rod (8) is connected to the moving platform through the rotating pair (9).

The present invention can also adopt following technical means to realize:

A three-translation-rotation parallel mechanism, the axis of the rotation pair (2) of the third branch chain is parallel to the axis of the rotation pair (2) of the first branch chain, and the axis of the rotation pair (2) of the fourth branch chain is parallel to the axis of the second branch chain The axes of the revolving pairs (2) of the branch chains are parallel; the axes of the revolving pairs (2) of the first and second branch chains are perpendicular to each other; the axes of rotation of the revolving pairs (2), (4), and (7) in each branch chain Always keep them parallel to each other.

The axes of the aforementioned second and fourth branch chain rotating pairs (9) are perpendicular to the axes of the respective branch chain rotating pairs (7), and the axes are arranged differently, and the axes of the two rotating pairs (9) are assembled in parallel It is on the moving platform (12) and kept parallel to the axis of the first kinematic branch chain rotating pair (2).

The axes of the aforementioned second and fourth branch chain rotating pairs (9) are perpendicular to the axes of the respective branch chain rotating pairs (7), and the axes are arranged differently, and the axes of the two rotating pairs (9) are assembled in parallel It is on the moving platform (12) and kept parallel to the axis of the first kinematic branch chain rotating pair (2).

Compared with the prior art, the present invention has the following obvious advantages and beneficial effects:

The mechanism structure is simple, there is no branch chain interference phenomenon, and the position and work space is large. The moving parts of the mechanism are light and the acceleration is high. Compared with the Delta mechanism, which can only move in three-dimensional translation, this mechanism adds a rotational degree of freedom, which makes the working end on the moving platform more flexible. It can realize three translations and one rotation in space, and the rotation is a regular rotation—its rotation axis is always parallel. The translation motion is that an object moves in space, and the line between any two points on it is in the process of motion. Always maintain a parallel movement. If a rotating joint is connected in series between the moving platform and the working end, the degree of freedom movement of the end effector can be realized.

Description of drawings

Fig. 1 is prior art Delta parallel structure robot;

Fig. 2 is prior art H4 parallel structure robot;

Fig. 3 is a schematic diagram of a parallelogram hinge structure in the prior art;

Fig. 4 is a parallel structure robot with three translations, one rotation and four degrees of freedom of the present invention;

Fig. 5 is the rotation schematic diagram of the parallel structure robot with three translations, one rotation and four degrees of freedom of the present invention;

Fig. 6 is the first and third motion branch chains of the novel parallel mechanism of Fig. 4 of the present invention;

Fig. 7 is the second and fourth motion branch chains of the novel parallel mechanism of Fig. 4 of the present invention;

Fig. 8 is the second embodiment of the parallel structure robot with three translations, one rotation and four degrees of freedom of the present invention.

Detailed ways

Specific embodiments of the present invention are described below in conjunction with accompanying drawing:

The three-translation-rotation parallel mechanism of the present invention can realize three-translation and one-rotation movement in space, and the rotation is a regular rotation movement—its rotation axis is always parallel. The translation movement is an object moving in space, and any two objects on it The connecting lines between the points always keep parallel movement during the movement. A novel parallel mechanism described in the present invention can realize movement along three coordinate axes of x, y and z and rotation around the y axis.

The working principle of the parallel mechanism is as follows: one end of the swing control arm passes through the rotating pair and the static platform, driven by the motor or other actuators, drives the swing control arm to swing repeatedly at a certain angle. The movement of the swing control arm drives the parallelogram hinge to move, and the parallelogram hinges on the second and fourth branch chains move in translation and rotate through the rotation pair to drive the connecting rod. The parallelogram hinges on the first and third branch chains and the connecting rods on the second and fourth branch chains jointly control the movement and rotation of the braking platform through the rotating pair connected with the moving platform. The working end of the robot or the tool of the machine tool can be fixed on the moving platform, and tasks such as picking and placing in industrial production, tool drilling, and cutting can be completed through the working end.

Embodiment one;

Fig. 4 is a specific embodiment 1 of the present invention. It can be seen from the figure that the four kinematic branch chains and the rotating pairs 2 connected to the static platform 1 are arranged symmetrically on the square static platform 1, wherein the structures of the first and third branch chains are shown in Figure 6; It can be seen that in the structure of the first branch chain, the swing control arm 3 is connected to the static platform 1 and the parallelogram hinge 6 through the rotating pair 2 and the rotating pair 5 respectively, and the axes of the rotating pairs 2 and 5 are arranged parallel to each other. The rotating pair 7 connects the parallelogram hinge 6 and the moving platform 12, and its axis is parallel to the axis of the rotating pair 2. The structure of the third branch chain is the same as that of the first branch chain, and the axes of the rotating shafts 2 connected to the static platform are parallel to each other.

The second and fourth branch chain structures are shown in Figure 7; wherein the axis of the rotating pair 2 is perpendicular to each other, and the second branch chain structure is different from the first branch chain in that a Connecting frame rod 8 and rotating pair 9. The structure of the fourth branch chain is the same as that of the second branch chain. The two axes of the rotating pair connected to the static platform are parallel to each other. The axes of the rotating pair 9 in the two branch chains are coaxially arranged on the plane of the moving platform and parallel to Rotating pair 2 axes of the first branch chain.

The mechanism is composed of a static platform 1, a dynamic platform 12, and four kinematic branch chains, and the four kinematic branch chains are arranged around the static platform, as shown in Fig. 1 . Please refer to Fig. 6, which is the structure of the first and third branch chains: as can be seen from the figure, the swing control arm 3 is connected to the static platform 1 and the parallelogram hinge 6 respectively through the rotation pairs 2 and 4, and the parallelogram hinge 6 It is connected with the moving platform 12 through the rotating pair 7 .

Please refer to Figure 7, which is the structure of the second and fourth branch chains. As can be seen from the figure, it is similar to the structure of the first and third branch chains. Connecting frame rod 8 and rotating pair 9, connecting frame rod 8 is connected rotating pair 7 and is connected with moving platform 12 through rotating pair 9.

Please refer to Figure 4, the coordinate system o-xyz is established at the geometric center of the rectangular static platform, the x-axis points to the center of the rotating pair 2 of the third branch chain, and the y-axis points to the center of the rotating pair 2 of the second branch chain The position, z-axis is determined by the right-hand rule. The rotation axis of the rotary pair 1 connected by the four branch chains to the static platform is arranged on the plane xoy.

The present invention is a novel parallel mechanism, the axis of the revolving pair 2 of the third branch is parallel to the axis of the revolving pair 2 of the first branch, the axis of the revolving pair 2 of the fourth branch is parallel to the axis of the revolving pair 2 of the second branch parallel. The axes of the rotary pairs 2 of the first and second branches are perpendicular to each other. The axes of rotation of the rotary pairs 2, 4, 7 in the branch chain are always parallel to each other.

The axes of the revolving pairs 9 of the second and fourth branch chains are perpendicular to the axes of the revolving pairs 7 of the respective branch chains, and can be arranged coaxially with the axes as shown in FIG. 4 , or as shown in FIG. 8 . solution, but the axes of the two revolving pairs 9 must be assembled on the moving platform 12 in parallel and kept parallel to the axis of the first kinematic branch revolving pair 2 . .

Implementation mode two

The following describes the implementation of different axes, as shown in Figure 8, which is another embodiment of the present invention, and the component parts and connection sequence of each branch chain remain unchanged. The difference is that the axes of the rotating pair 9 in the second and fourth branch chains are not coaxially arranged on the moving platform, but they are all kept parallel to the axes of the rotating pair 2 of the first branch chain. The advantages and disadvantages of the coaxial and non-coaxial arrangement schemes in terms of mechanism performance are: the coaxial arrangement scheme has a symmetrical structure, the force on the moving platform is average, the movement precision of the mechanism is high, and the error is small; The end link 8 of the motion branch chain keeps translation all the time, and the second and fourth branch chains do not affect the rotational movement of the moving platform, so the rotational flexibility of the mechanism is not strong. Mechanisms with different shaft layout schemes are asymmetrical, and the force on the moving platform is uneven, and its movement accuracy is low and the error is large; more sensitive.

Finally, it should be noted that: the above embodiments are only used to illustrate the present invention rather than limit the technical solutions described in the present invention; Those of ordinary skill in the art should understand that the present invention can still be modified or equivalently replaced; and all technical solutions and improvements that do not depart from the spirit and scope of the invention should be covered by the claims of the present invention.

Claims (4)

1, a kind of three-translation and one-rotation parallel mechanism is made of silent flatform (1), moving platform (12) and four movement branched chain; Described four movement branched chain are arranged on around the silent flatform, wherein, the swing control arm (3) of first and third side chain links to each other with silent flatform (1), parallelogram hinge (6) by revolute pair (2), (4) respectively, and described parallelogram hinge (6) links to each other with moving platform (12) by revolute pair (7); The second, the swing control arm (3) of four side chains is connected respectively to revolute pair (2), (4); It is characterized in that:

Coordinate system o-xyz is set up in the geometric center position of described silent flatform, the x axle points to the center position of the revolute pair (2) of the 3rd side chain, the y axle points to the center of the second side chain revolute pair (2), the z axle determined by the right-hand rule, and the pivot center of the revolute pair (1) that four side chains are connected with silent flatform is arranged on the xoy of plane; Side link (8) and revolute pair (9) have been increased between the revolute pair of described second, four side chains (2), (4) and the moving platform (12); Side link (8) connects revolute pair (7) and links to each other with moving platform (12) by revolute pair (9): four side chain one ends link to each other with silent flatform (1) by swing control arm (3), swing control arm (3) connects parallelogram hinge (6), the other end of side chain is to be linked to each other with moving platform (12) by revolute pair (7) by parallelogram hinge (6) on first and third side chain, parallelogram hinge (6) on second, four side chains connects side link (8), is connected to moving platform by side link (8) by revolute pair (9).

2, a kind of three-translation and one-rotation parallel mechanism according to claim 1, it is characterized in that: the axis of the revolute pair of the 3rd side chain (2) is parallel with the axis of the first side chain revolute pair (2), and the axis of the revolute pair of the 4th side chain (2) is parallel with the axis of the second side chain revolute pair (2); The axis of the revolute pair of first and second side chain (2) is vertical mutually; The pivot center of revolute pair (2), (4), (7) remains and is parallel to each other in every side chain.

3, three-translation and one-rotation parallel mechanism according to claim 1 and 2, it is characterized in that: the second, the axis normal of the revolute pair of four side chains (9) in the axis of side chain revolute pair (7) separately, take axis out-of-alignment arrangement, the axis of two revolute pairs (9) is parallel to be assemblied in moving platform (12) and to go up and keep parallel with first movement branched chain revolute pair (2) axis.

4, three-translation and one-rotation parallel mechanism according to claim 3, it is characterized in that: the second, the axis normal of the revolute pair of four side chains (9) in the axis of side chain revolute pair (7) separately, take axis out-of-alignment arrangement, the axis of two revolute pairs (9) is parallel to be assemblied in moving platform (12) and to go up and keep parallel with first movement branched chain revolute pair (2) axis.

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