A metamorphic parallel mechanism with three modes

Abstract

The present invention relates to a variable-cell parallel mechanism with three modes, comprising a fixed platform, a moving platform, a first branch chain, a second branch chain and a third branch chain; the second branch chain and the third branch chain have the same structure and are symmetrically arranged with respect to the first branch chain; the first branch chain includes five revolute pairs, and the second branch chain and the third branch chain each include six revolute pairs and one U pair; four revolute pairs near the fixed platform in the second and third branch chains form a parallelogram configuration, and the two revolute pairs connected to the fixed platform in the parallelogram configuration are moved through two slide rails in the fixed platform. The present invention altogether includes seven driving pairs, the branch chains are symmetrically distributed, and after adding a closed-loop mechanism, it has strong load-bearing capacity, simple calculation and control, and the three motion modes are completely independent and do not interfere with each other, and can be applied to fields such as cargo handling and sorting, large component precision machine tools, flight simulators, rehabilitation medical robots, space robotic arms, packing production line operations, robot spraying, friction stir welding, 3D printing, machining manufacturing, etc.

Description

Technical Field

[0001] The present invention relates to the technical field of robots, and in particular, to a variable-cell parallel mechanism with three modes. Background Art

[0002] Research on intelligent reconfigurable mechanisms and robots with the abilities of actively adapting to variable environments and passively adapting to unexpected situations is of great significance to the innovation and development of the advanced manufacturing field and the new generation of robots in our country.

[0003] There are few existing multi-mode and reconfigurable parallel mechanisms. However, with the development of technology, in many fields such as industrial production, aerospace, and medical rehabilitation, reconfigurable mechanisms that can freely switch motion modes according to changes in the working environment are needed.

[0004] Currently, there are few variable-cell parallel mechanisms that can achieve three modes of 3T, 1T2R, and 2T1R. Moreover, most of them have complex structures, poor flexibility, complex mode-switching processes, easy interference between motion modes, poor kinematic and dynamic performance, and poor load-carrying capacity. Such mechanisms have certain application prospects in fields such as welding, drilling and riveting surface machining, large equipment attitude regulators, and industrial robots. Summary of the Invention

[0005] In view of the above problems, the purpose of the present invention is to provide a variable-cell parallel mechanism with three modes. The configuration of the mechanism branches is simple, the structure is compact, the stiffness is high, the number of driving pairs is more than the degrees of freedom during work, and the three working modes can be completely controlled. By driving different driving pairs, the mechanism can achieve three working modes of three translations, two translations and one rotation, and one translation and two rotations, and a working space with superior performance is comprehensively obtained, eliminating the singular configuration and increasing the operability of the mechanism.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A variable-cell parallel mechanism with three modes proposed by the present invention includes a moving platform, a first branch chain, a second branch chain, a third branch chain, and a fixed platform; the first branch chain, the second branch chain, and the third branch chain are arranged between the moving platform and the fixed platform, and the three branch chains are symmetrically distributed along the center; the structures of the second branch chain and the third branch chain are the same and are symmetrically arranged with respect to the first branch chain; five revolute pairs are sequentially arranged between the moving platform and the fixed platform in the first branch chain; six revolute pairs and a U pair are sequentially arranged between the moving platform and the fixed platform in the second branch chain and the third branch chain, and four revolute pairs close to the fixed platform form a parallelogram configuration, and the second revolute pair is connected to the middle of the upper end of the parallelogram configuration through the U pair; the two lower revolute pairs in the parallelogram configuration are connected to the fixed platform through a slide rail prismatic pair; the second revolute pair close to the moving platform in the first branch chain, the second revolute pair close to the moving platform in the second branch chain and the third branch chain, and the four slide rail prismatic pairs on the fixed platform are driving pairs, that is, the parallel mechanism includes a total of seven driving pairs, and the seven driving pairs drive the moving platform to realize the motion and mutual switching between the spatial three-translation working mode, the two-translation one-rotation working mode, and the one-translation two-rotation working mode with respect to the fixed platform.

[0008] Further, the fixed platform is a regular hexagon, and two parallel slide rails are respectively arranged at positions corresponding to the second branch chain and the third branch chain; the moving platform is a regular triangular structure, and fixed hinge supports are arranged at three centrally symmetric angles for connecting with the three branch chains.

[0009] Further, the first branch chain includes a first connecting rod, a second connecting rod, a third connecting rod, a fourth connecting rod, a first revolute pair, a second revolute pair, a third revolute pair, a fourth revolute pair, and a fifth revolute pair; the top end of the first connecting rod is connected to the fixed hinge support on the moving platform through the first revolute pair; the top end of the second connecting rod is connected to the end of the first connecting rod through the second revolute pair; the end of the second connecting rod is connected to the top end of the third connecting rod through the third revolute pair; the end of the third connecting rod is connected to the top end of the fourth connecting rod through the fourth revolute pair; the end of the fourth connecting rod is connected to the fixed hinge support on the fixed platform through the fifth revolute pair.

[0010] Further, the axes of the first revolute pair, the second revolute pair, and the third revolute pair are parallel to each other; the axes of the fourth revolute pair and the fifth revolute pair are parallel to each other, and the axial direction of the fourth revolute pair and the fifth revolute pair is perpendicular to the axial direction of the first revolute pair, the second revolute pair, and the third revolute pair.

[0011] Further, the second and third branch chains have the same structure, including a sliding hinge support I, a sliding hinge support II, a connecting rod I, a connecting rod II, a connecting rod III, a connecting rod IV, a connecting rod V, a rotating pair I, a rotating pair II, a rotating pair III, a rotating pair IV, a rotating pair V, a rotating pair VI, and a Hooke's joint; the top end of the connecting rod I is connected to the fixed hinge support on the moving platform through the rotating pair I; the top end of the connecting rod II is connected to the end of the connecting rod I through the rotating pair II; the middle of the top end of the connecting rod III is connected to the end of the connecting rod II through the Hooke's joint; the two ends of the connecting rod III are respectively connected to the connecting rod IV and the connecting rod V through the rotating pair III and the rotating pair IV to form a parallelogram configuration, and the respective ends of the connecting rod IV and the connecting rod V are connected to the sliding hinge support I and the sliding hinge support II through the rotating pair V and the rotating pair VI, and the sliding hinge support I and the sliding hinge support II are respectively connected to the two parallel sliding rail pairs at the corresponding positions on the fixed platform.

[0012] Further, in the second and third branch chains, the axis direction of one of the rotating pairs of the Hooke's joint is perpendicular to the axis directions of the other rotating pairs of the branch chain; the sliding hinge support I and the sliding hinge support II can achieve collinear rotation axes through cooperation with the sliding rail pairs on the fixed platform.

[0013] Further, when the sliding hinge support I and the sliding hinge support II in the second or third branch chain achieve collinear rotation axes through the sliding rails on the fixed platform, the mechanism enters a working mode of two translations and one rotation; when the sliding hinge support I and the sliding hinge support II in the second and third branch chains simultaneously achieve collinear rotation axes through the sliding rails on the fixed platform, the mechanism enters a working mode of one translation and two rotations; when the sliding hinge supports in the second and third branch chains are separated and fixed on both sides so that the connecting rod IV and the connecting rod V are parallel, the mechanism enters a working mode of three translations. The three modes do not interfere with each other and no singular configurations will occur.

[0014] The present invention has the following beneficial effects compared with the prior art:

[0015] The present invention drives the moving platform to achieve the movement and mutual switching of three working modes of three translations, two translations and one rotation, and one translation and two rotations relative to the fixed platform by driving seven kinematic pairs to cope with different working environments. In the parallel mechanism of the present invention, the branch chains are symmetrically distributed, with strong load-bearing capacity, simple calculation and control, and can be widely applied to various fields such as operations on packing production lines, material handling, robot spraying, friction stir welding, 3D printing, and machining manufacturing. Description of the Drawings

[0016] Figure 1 is a schematic diagram of the overall structure of the present invention;

[0017] Figure 2It is a schematic structural diagram of the three-translation working mode of the present invention;

[0018] Figure 3 It is a schematic structural diagram of the two-translation and one-rotation working mode of the present invention;

[0019] Figure 4 It is a schematic structural diagram of the one-translation and two-rotation working mode of the present invention. Specific embodiments

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0021] It should be noted that in the description of the present invention, it should be noted that the orientation or positional relationship indicated by terms such as "upper", "lower", "top", "bottom", "one side", "the other side", "left", "right", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating that the device or element must have a specific orientation, be constructed and operated in a specific orientation.

[0022] Refer to the appendix Figures 1-4 , which gives the specific structure of an embodiment of a variable-cell parallel mechanism with three modes proposed by the present invention. The parallel mechanism includes a first branch chain 1, a second branch chain 2, a third branch chain 3, a fixed platform 4, and a moving platform 5.

[0023] In this embodiment, the fixed platform 4 is a regular hexagon, and two parallel slide rails 41 are respectively provided on the two sides corresponding to the second branch chain 2 and the third branch chain 3; the moving platform 5 is a regular triangular structure, and a fixed hinge support 51 is installed at each of the three centrally symmetric corners, respectively for connecting with the first branch chain 1, the second branch chain 2, and the third branch chain 3; a fixed hinge support 51 is installed on the side of the fixed platform 4 corresponding to the first branch chain 1 for connecting with the first branch chain 1.

[0024] The first branch chain 1, the second branch chain 2 and the third branch chain 3 are circumferentially and evenly connected between the moving platform 5 and the fixed platform 4, and the three branch chains are symmetrically distributed about the center; the second branch chain 2 and the third branch chain 3 have the same structure and are symmetrically arranged with respect to the first branch chain 1; wherein, five revolute pairs are sequentially arranged between the moving platform 5 and the fixed platform 4 on the first branch chain 1; six revolute pairs and one U pair are sequentially arranged between the moving platform 5 and the fixed platform 4 on the second branch chain 2 and the third branch chain 3. Four revolute pairs close to the fixed platform 4 in the second branch chain 2 and the third branch chain 3 form a parallelogram configuration, and the second revolute pair is connected to the middle of the upper end of the parallelogram configuration through the U pair; the two revolute pairs at the lower end in the parallelogram configuration are connected to the fixed platform 4 through a sliding rail 41 prismatic pair; the second revolute pair close to the moving platform 5 in the first branch chain 1, the second revolute pair close to the moving platform 5 in the second branch chain 2 and the third branch chain 3, and the four sliding rail prismatic pairs on the fixed platform 4 are driving pairs. That is, the parallel mechanism of the present invention altogether includes seven driving pairs, and the seven driving pairs drive the moving platform 5 to realize the motion and mutual switching between the spatial three-translation working mode, the two-translation one-rotation working mode and the one-translation two-rotation working mode relative to the fixed platform 4.

[0025] Specifically, the first branch chain 1 includes a first connecting rod 11, a second connecting rod 12, a third connecting rod 13, a fourth connecting rod 14, a first revolute pair 15, a second revolute pair 16, a third revolute pair 17, a fourth revolute pair 18 and a fifth revolute pair 19; the top end of the first connecting rod 11 is connected to the corresponding fixed hinge support 51 on the moving platform 5 through the first revolute pair 15; the top end of the second connecting rod 12 is connected to the end of the first connecting rod 11 through the second revolute pair 16; the end of the second connecting rod 12 is connected to the top end of the third connecting rod 13 through the third revolute pair 17; the end of the third connecting rod 13 is connected to the top end of the fourth connecting rod 14 through the fourth revolute pair 18; the end of the fourth connecting rod 14 is connected to the corresponding fixed hinge support 51 on the fixed platform 4 through the fifth revolute pair 19.

[0026] Wherein, the axes of the first revolute pair 15, the second revolute pair 16 and the third revolute pair 17 close to the moving platform 5 are parallel to each other; the axes of the fourth revolute pair 18 and the fifth revolute pair 19 close to the fixed platform 4 are parallel to each other, and the axial directions of the fourth revolute pair 18 and the fifth revolute pair 19 are perpendicular to the axial directions of the first revolute pair 15, the second revolute pair 16 and the third revolute pair 17.

[0027] The second branch chain 2 and the third branch chain 3 have the same structure.

[0028] Among them, the second branch chain 2 includes a sliding hinge support I 21, a sliding hinge support II 22, a connecting rod I 23, a connecting rod II 24, a connecting rod III 25, a connecting rod IV 26, a connecting rod V 27, a revolute pair I 28, a revolute pair II 29, a revolute pair III 210, a revolute pair IV 211, a revolute pair V 212, a revolute pair VI 213 and a Hooke's joint 214; the top end of the connecting rod I 23 is connected to the corresponding fixed hinge support 51 on the moving platform 5 through the revolute pair I 28; the top end of the connecting rod II 24 is connected to the end of the connecting rod I 23 through the revolute pair II 29; the connecting rod III 25 is horizontally placed, and the middle of its upper end face is connected to the end of the connecting rod II 24 through the Hooke's joint 214; one end of the connecting rod III 25 is correspondingly connected to the upper end of the connecting rod IV 26 through the revolute pair III 210; the other end of the III 25 is correspondingly connected to the upper end of the connecting rod V 27 through the revolute pair IV 211; the connecting rod III 35, the connecting rod IV 36, the connecting rod V 37, the revolute pair III 310, the revolute pair IV 311, the revolute pair V 312 and the revolute pair VI 313 together form a closed-loop parallelogram configuration; the end of the connecting rod IV 26 is connected to the sliding hinge support I 21 through the revolute pair V 212; the end of the connecting rod V 27 is connected to the sliding hinge support II 22 through the revolute pair VI 213; the sliding hinge support I 21 and the sliding hinge support II 22 are respectively connected to two parallel slide rails 41 at corresponding positions on the fixed platform 4 through a moving pair.

[0029] Correspondingly, the third branch chain 3 includes a sliding hinge support I31, a sliding hinge support II32, a connecting rod I33, a connecting rod II34, a connecting rod III35, a connecting rod IV36, a connecting rod V37, a rotating pair I38, a rotating pair II39, a rotating pair III310, a rotating pair IV311, a rotating pair V312, a rotating pair VI313, and a Hooke's joint 314; the top end of the connecting rod I33 is connected to the corresponding fixed hinge support 51 on the moving platform 5 through the rotating pair I38; the top end of the connecting rod II34 is connected to the end of the connecting rod I33 through the rotating pair II39; the connecting rod III35 is horizontally placed, and the middle of its upper end surface is connected to the end of the connecting rod II34 through the Hooke's joint 314; one end of the connecting rod III35 is correspondingly connected to the upper end of the connecting rod IV36 through the rotating pair III310; the other end of the III35 is correspondingly connected to the upper end of the connecting rod V37 through the rotating pair IV311; the connecting rod III35, the connecting rod IV36, the connecting rod V37, the rotating pair III310, the rotating pair IV311, the rotating pair V312, and the rotating pair VI313 together form a closed-loop parallelogram configuration; the end of the connecting rod IV36 is connected to the sliding hinge support I31 through the rotating pair V312; the end of the connecting rod V37 is connected to the sliding hinge support II33 through the rotating pair VI313; the sliding hinge support I31 and the sliding hinge support II33 are respectively connected to two parallel sliding rails 41 at corresponding positions on the fixed platform 4 through a moving pair.

[0030] In the second branch chain 2 and the third branch chain 3, the direction of the axis of one of the rotating pairs of the Hooke's joint is perpendicular to the directions of the axes of the other rotating pairs of the branch chain; the sliding hinge support I and the sliding hinge support II can achieve collinear rotation axes through the cooperation of the moving pair with the sliding rail 41 on the fixed platform 4.

[0031] When the sliding hinge support I and the sliding hinge support II in the second branch chain 2 or the third branch chain 3 achieve collinear rotation axes through the sliding rail 41 on the fixed platform 4, the mechanism enters a working mode of two translations and one rotation; when the sliding hinge support I and the sliding hinge support II in the second branch chain 2 and the third branch chain 3 simultaneously achieve collinear rotation axes through the sliding rail 41 on the fixed platform 4, the mechanism enters a working mode of one translation and two rotations. When the sliding hinge supports in the second branch chain 2 and the third branch chain 3 are separated and fixed on both sides of the sliding rail 41 so that the connecting rod IV and the connecting rod V are parallel to each other, the mechanism enters a working mode of three translations. The three modes do not interfere with each other and no singular configuration will occur.

[0032] Matters not covered in this invention are all well-known technologies.

[0033] The embodiments described above are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A variable cell parallel mechanism with three modes, characterized in that: The parallel mechanism includes a moving platform, a first branch chain, a second branch chain, a third branch chain and a fixed platform; the first branch chain, the second branch chain and the third branch chain are arranged between the moving platform and the fixed platform, and the three branch chains are symmetrically distributed along the center; the structures of the second branch chain and the third branch chain are the same and are symmetrically arranged with respect to the first branch chain; five revolute pairs are sequentially arranged on the first branch chain from the moving platform to the fixed platform; six revolute pairs and a U pair are sequentially arranged on the second branch chain and the third branch chain from the moving platform to the fixed platform, wherein four revolute pairs close to the fixed platform form a parallelogram configuration, and the second revolute pair is connected to the middle of the upper end of the parallelogram configuration through a U pair; the two revolute pairs at the lower end of the parallelogram configuration are connected to the fixed platform through a sliding rail prismatic pair; the second revolute pair close to the moving platform on the first branch chain, the second revolute pair close to the moving platform on the second branch chain and the third branch chain, and the four sliding rail prismatic pairs on the fixed platform are driving pairs, that is, the parallel mechanism includes a total of seven driving pairs, and the seven driving pairs drive the moving platform to realize the motion and mutual switching between the spatial three-translation working mode, the two-translation one-rotation working mode and the one-translation two-rotation working mode relative to the fixed platform; The fixed platform is a regular hexagon, and two parallel sliding rails are respectively arranged at positions corresponding to the second branch chain and the third branch chain; the moving platform is a regular triangular structure, and fixed hinge supports are arranged at three centrally symmetric corners for connecting with the three branch chains; The first branch chain includes a first connecting rod, a second connecting rod, a third connecting rod, a fourth connecting rod, a first revolute pair, a second revolute pair, a third revolute pair, a fourth revolute pair and a fifth revolute pair; the top end of the first connecting rod is connected to the fixed hinge support on the moving platform through the first revolute pair; the top end of the second connecting rod is connected to the end of the first connecting rod through the second revolute pair; the end of the second connecting rod is connected to the top end of the third connecting rod through the third revolute pair; the end of the third connecting rod is connected to the top end of the fourth connecting rod through the fourth revolute pair; the end of the fourth connecting rod is connected to the fixed hinge support on the fixed platform through the fifth revolute pair; The axes of the first revolute pair, the second revolute pair and the third revolute pair are parallel to each other; the axes of the fourth revolute pair and the fifth revolute pair are parallel to each other, and the axis directions of the fourth revolute pair and the fifth revolute pair are perpendicular to the axes of the first revolute pair, the second revolute pair and the third revolute pair; The second and third branch chains have the same structure, including a sliding hinge support I, a sliding hinge support II, a connecting rod I, a connecting rod II, a connecting rod III, a connecting rod IV, a connecting rod V, a revolute pair I, a revolute pair II, a revolute pair III, a revolute pair IV, a revolute pair V, a revolute pair VI, and a Hooke's joint; the top of the connecting rod I is connected to the fixed hinge support on the moving platform through the revolute pair I; the top of the connecting rod II is connected to the end of the connecting rod I through the revolute pair II; the middle of the top of the connecting rod III is connected to the end of the connecting rod II through the Hooke's joint; the two ends of the connecting rod III are respectively connected to the connecting rod IV and the connecting rod V through the revolute pair III and the revolute pair IV to form a parallelogram configuration, and the ends of the connecting rod IV and the connecting rod V are respectively connected to the sliding hinge support I and the sliding hinge support II through the revolute pair V and the revolute pair VI, and the sliding hinge support I and the sliding hinge support II are respectively connected to the two parallel slide rail moving pairs at the corresponding positions on the fixed platform; In the second and third branch chains, the axis direction of one of the revolute pairs of the Hooke's joint is perpendicular to the axis directions of the other revolute pairs of the branch chain; the sliding hinge support I and the sliding hinge support II can achieve collinear rotation axes through cooperation with the slide rail moving pairs on the fixed platform; When the sliding hinge support I and the sliding hinge support II in the second or third branch chain achieve collinear rotation axes through the slide rails on the fixed platform, the mechanism enters a working mode of two translations and one rotation; when the sliding hinge support I and the sliding hinge support II in the second and third branch chains achieve collinear rotation axes simultaneously through the slide rails on the fixed platform, the mechanism enters a working mode of one translation and two rotations; when the sliding hinge supports in the second and third branch chains are separated and fixed on both sides to make the connecting rod IV and the connecting rod V parallel, the mechanism enters a working mode of three translations. The three modes do not interfere with each other and no singular configurations will occur.

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