A metamorphic parallel mechanism with two modes of 2T and 1T1R

Abstract

The present invention relates to a metamorphic parallel mechanism with two modes of 2T and 1T1R, including a fixed platform and a moving platform. A first branch chain, a second branch chain, and a third branch chain are arranged between the fixed platform and the moving platform, and the second branch chain and the third branch chain are symmetrically arranged with respect to the first branch chain. The three branch chains of this parallel mechanism altogether include four driving pairs, and the four driving pairs drive the moving platform to realize the motion and mutual switching of two working modes of two translations and one translation and one rotation relative to the fixed platform, so as to adapt to different working environments to change the working mode and the corresponding working space. In the present invention, the branch chains are symmetrically distributed. After adding a closed-loop mechanism, the load-bearing capacity is strong, the calculation and control are simple, and the two motion modes are completely independent and do not interfere with each other. It can be applied to the fields of cargo handling and sorting, large component precision machine tools, flight simulators, rehabilitation medical robots, aerospace robotic arms, operations on packing production lines, 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 particularly to a metamorphic parallel mechanism with two modes of 2T and 1T1R. Background Art

[0002] Parallel mechanisms with fixed degrees of freedom are widely used in industrial robots, motion simulators, attitude controllers, medical robots, etc. due to their high stiffness, large load-bearing capacity, high precision, etc. 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 required. Under this background, scholars' research on reconfigurable parallel mechanisms has gradually deepened. Reconfigurable parallel mechanisms are mainly divided into two types, including motion bifurcation parallel mechanisms and metamorphic parallel mechanisms. By using variable-degree-of-freedom metamorphic kinematic pairs to replace traditional constant-degree-of-freedom kinematic pairs during motion, the constraint properties of the mechanism's branches change during motion, and finally a new metamorphic mechanism is designed. Compared with motion bifurcation parallel mechanisms, there is no motion bifurcation point, and the two motion modes are completely independent.

[0003] Currently, there are few metamorphic parallel mechanisms that can achieve two modes of 2T and 1T1R. 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-bearing capacity. This type of mechanism has certain application prospects in fields such as welding, drilling and riveting surface machining, large equipment attitude regulators, and industrial robots.

[0004] Therefore, how to change the current situation in the prior art where the mode switching process of the metamorphic parallel mechanism that can achieve two modes of 2T and 1T1R is complex, and the motion performance is poor and the load-bearing capacity is poor has become a technical problem that needs to be urgently solved by those skilled in the art. Summary of the Invention

[0005] In view of the above problems, the purpose of the present invention is to provide a metamorphic parallel mechanism with two modes of 2T and 1T1R. The branch configuration of this mechanism 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 two working modes are completely controllable. By driving different driving pairs, this mechanism can achieve two working modes of two translations and one translation and one rotation, and comprehensively obtain a working space with excellent performance. At the same time, the singular configuration is eliminated, and the operability of the mechanism is increased.

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

[0007] A variable-cell parallel mechanism with two modes of 2T and 1T1R 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 connected between the moving platform and the fixed platform; the second branch chain and the third branch chain are symmetrically arranged with respect to the first branch chain;

[0008] The first branch chain includes five revolute pairs and two Hooke joints from the moving platform to the fixed platform. Among them, two revolute pairs and two Hooke joints form a parallelogram configuration, and the two revolute pairs in this parallelogram configuration are respectively connected to the corresponding prismatic pairs of the fixed platform;

[0009] The second branch chain sequentially includes two revolute pairs and a second branch chain C pair from the moving platform to the fixed platform;

[0010] The third branch chain sequentially includes a spherical pair, a prismatic pair and a revolute pair from the moving platform to the fixed platform;

[0011] The revolute pair in the second branch chain, the prismatic pair in the third branch chain, and the two prismatic pairs at the bottom of the first branch chain are driving pairs, that is, a total of four driving pairs. The four driving pairs drive the moving platform to realize the movement and mutual switching between the spatial two-translation working mode and the one-translation-one-rotation working mode relative to the fixed platform.

[0012] Further, the fixed platform is of a rectangular structure, and two parallel moving slide rails are provided at positions corresponding to the two revolute pairs at the bottom of the first branch chain, and fixed hinge supports are provided at positions corresponding to the second branch chain and the third branch chain; the moving platform is of an isosceles triangle structure, and a spherical pair hinge support corresponding to the third branch chain and a revolute pair hinge support corresponding to the second branch chain are respectively installed at the symmetric two base angle positions, and a revolute pair hinge support corresponding to the first branch chain is installed at the top angle position; the rotation axis of the revolute pair hinge support is parallel to the moving platform; the rotation axis of the revolute pair hinge support is perpendicular to the moving platform.

[0013] Furthermore, the first branch chain includes a first sliding hinge support, a second sliding hinge support, a first branch chain link I, a first branch chain link II, a first branch chain link III, a first branch chain link IV, a first branch chain link V, a first branch chain revolute pair I, a first branch chain revolute pair II, a first branch chain revolute pair III, a first branch chain revolute pair IV, a first branch chain revolute pair V, a first Hooke joint, and a second Hooke joint; the top end of the first branch chain link I is connected to a corresponding revolute joint support on the moving platform through the first branch chain revolute pair I; the top end of the first branch chain link II is connected to the end of the first branch chain link I through the first branch chain revolute pair II; the end of the first branch chain link II is connected to the middle part of the upper end of the first branch chain link III through the first branch chain revolute pair III; the left and right ends of the first branch chain link III are respectively connected to the first branch chain link IV and the first branch chain link V through the first Hooke joint and the second Hooke joint to form a parallelogram configuration; the end of the first branch chain link IV is connected to the first sliding hinge support through the first branch chain revolute pair IV; the end of the first branch chain link V is connected to the second sliding hinge support through the first branch chain revolute pair V; the first sliding hinge support and the second sliding hinge support are respectively connected to corresponding moving slide rails on the fixed platform.

[0014] Furthermore, the axis direction of the first branch chain revolute pair I is perpendicular to the axis directions of the first branch chain revolute pair II and the first branch chain revolute pair III; the first branch chain link III, the first branch chain link IV, and the first branch chain link V form a closed-loop parallelogram configuration through the first Hooke joint and the second Hooke joint; the first sliding hinge support and the second sliding hinge support are connected through a slide rail pair on the fixed platform to achieve collinear rotation axes.

[0015] Furthermore, the second branch chain includes a second branch chain link I, a second branch chain link II, a second branch chain revolute pair I, a second branch chain revolute pair II, and a second branch chain C pair; the top end of the second branch chain link I is connected to a corresponding revolute joint support on the moving platform through the second branch chain revolute pair I; the end of the second branch chain link I is connected to the top end of the second branch chain link II through the second branch chain revolute pair II; the end of the second branch chain link II is connected to a corresponding fixed hinge support on the fixed platform through the second branch chain C pair.

[0016] Furthermore, the rotation axes of the two revolute pairs in the second branch chain are parallel to the rotation axis of the second branch chain C pair.

[0017] Further, the third branch chain includes a first third-branch connecting rod, a second third-branch connecting rod, a third-branch rotating pair, a third-branch spherical pair, and a third-branch sliding pair; the top end of the first third-branch connecting rod is connected to a corresponding spherical pair hinge support on the moving platform through the third-branch spherical pair; the end of the first third-branch connecting rod is connected to the top end of the second third-branch connecting rod through the third-branch sliding pair; the end of the second third-branch connecting rod is connected to a corresponding fixed hinge support on the fixed platform through the third-branch rotating pair.

[0018] Further, the moving direction of the third-branch sliding pair is perpendicular to the rotation axis of the third-branch rotating pair and passes through the center of the sphere of the third-branch spherical pair.

[0019] The present invention has the following beneficial effects compared with the prior art:

[0020] By driving four kinematic pairs, the present invention drives the moving platform to move and switch between two working modes of two translations and one translation and one rotation relative to the fixed platform to cope with different working environments. In the present invention, the branch chains are symmetrically distributed, with strong load-bearing capacity, simple calculation and control, and can be applied to operations in packing production lines, material handling, robot spraying, friction stir welding, 3D printing, machining manufacturing and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic diagram of the overall structure of the present invention;

[0022] Figure 2 is a schematic diagram of the structure of the present invention in the two-translation working mode;

[0023] Figure 3 is a schematic diagram of the structure of the present invention in the one-translation and one-rotation working mode. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] 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, other drawings can be obtained based on these drawings without creative efforts.

[0025] It should be noted that in the description of the present invention, 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, and 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.

[0026] See the attached Figures 1-3, a specific structure of an embodiment of a metamorphic parallel mechanism with two modes of 2T and 1T1R proposed by the present invention is given. The parallel mechanism includes a first branch chain 1, a second branch chain 2, a third branch chain 3, a moving platform 4, and a fixed platform 5; the first branch chain 1, the second branch chain 2, and the third branch chain 3 are connected between the moving platform 4 and the fixed platform 5; wherein the second branch chain 2 and the third branch chain 3 are arranged centered on the first branch chain; the first branch chain 1 includes five revolute pairs and two Hooke joints from the moving platform 4 to the fixed platform 5, and a parallelogram configuration is formed by two revolute pairs and two Hooke joints, and the two revolute pairs in the parallelogram configuration are respectively connected to the corresponding prismatic pairs of the fixed platform 5; the second branch chain 2 successively includes two revolute pairs and a second branch chain C pair from the moving platform 4 to the fixed platform 5; the third branch chain 3 successively includes a spherical pair, a prismatic pair, and a revolute pair from the moving platform 4 to the fixed platform 5.

[0027] In this embodiment, the fixed platform 5 is of a rectangular structure, and two parallel moving slide rails 51 are provided at positions corresponding to the two revolute pairs at the bottom of the parallelogram configuration in the first branch chain 1, and fixed hinge supports are provided at positions corresponding to the ends of the second branch chain 2 and the third branch chain 3; the moving platform 4 is of an isosceles triangle structure, and a spherical pair hinge support corresponding to the third branch chain 3 and a revolute pair hinge support corresponding to the second branch chain 2 are respectively installed at the symmetric two base angle positions, and a revolute pair hinge support corresponding to the first branch chain 1 is installed at the vertex angle position; the rotation axis of the revolute pair hinge support is parallel to the moving platform 4; the rotation axis of the revolute pair hinge support is perpendicular to the moving platform 4.

[0028] Specifically, the first branch chain 1 includes the first branch chain connecting rod I 11, the first branch chain connecting rod II 12, the first branch chain connecting rod III 13, the first branch chain connecting rod IV 14, the first branch chain connecting rod V 15, the first branch chain revolute pair I 16, the first branch chain revolute pair II 17, the first branch chain revolute pair III 18, the first branch chain revolute pair IV 19, the first branch chain revolute pair V 110, the first Hooke's joint 111, the second Hooke's joint 112, the first sliding hinge support 113 and the second sliding hinge support 114; the top end of the first branch chain connecting rod I 11 is connected to the corresponding revolute hinge support on the moving platform 4 through the first branch chain revolute pair I 16; the top end of the first branch chain connecting rod II 12 is connected to the end of the first branch chain connecting rod I 11 through the first branch chain revolute pair II 17; the end of the first branch chain connecting rod II 12 is connected to the middle of the upper end of the first branch chain connecting rod III 13 through the first branch chain revolute pair III 18; the left and right ends of the first branch chain connecting rod III 13 are respectively connected to the first branch chain connecting rod IV 14 and the first branch chain connecting rod V 15 through the first Hooke's joint 111 and the second Hooke's joint 112 to form a parallelogram configuration; the end of the first branch chain connecting rod IV 14 is connected to the first sliding hinge support 113 through the first branch chain revolute pair IV 19; the end of the first branch chain connecting rod V 15 is connected to the second sliding hinge support 114 through the first branch chain revolute pair V 110; the first sliding hinge support 113 and the second sliding hinge support 114 are respectively connected to the corresponding moving slide rails 51 on the fixed platform 5.

[0029] Among them, the axis direction of the first branch chain revolute pair I 16 is perpendicular to the axis directions of the first branch chain revolute pair II 17 and the first branch chain revolute pair III 18; the first branch chain connecting rod III 13, the first branch chain connecting rod IV 14 and the first branch chain connecting rod V 15 form a closed-loop parallelogram configuration through the first Hooke's joint 111 and the second Hooke's joint 112; the first sliding hinge support 113 and the second sliding hinge support 114 are connected through a moving pair with the slide rail 51 on the fixed platform 5, and the rotation axes of the first branch chain revolute pair IV 19 and the first branch chain revolute pair V 110 can be collinear.

[0030] The second branch chain 2 includes the second branch chain connecting rod I 21, the second branch chain connecting rod II 22, the second branch chain revolute pair I 23, the second branch chain revolute pair II 24 and the second branch chain C pair 25; the top end of the second branch chain connecting rod I 21 is connected to the corresponding revolute hinge support on the moving platform 4 through the second branch chain revolute pair I 23; the end of the second branch chain connecting rod I 21 is connected to the top end of the second branch chain connecting rod II 22 through the second branch chain revolute pair II 24; the end of the second branch chain connecting rod II 22 is connected to the corresponding fixed hinge support on the fixed platform 5 through the second branch chain C pair 25. Among them, the rotation axes of the second branch chain revolute pair I 23 and the second branch chain revolute pair II 24 are parallel to the rotation axis of the second branch chain C pair 25.

[0031] The third branch chain 3 includes a third branch chain connecting rod I31, a third branch chain connecting rod II32, a third branch chain revolute pair 33, a third branch chain spherical pair 34 and a third branch chain prismatic pair 35; the top end of the third branch chain connecting rod I31 is connected to a corresponding spherical pair hinge support on the moving platform 4 through the third branch chain spherical pair 34; the end of the third branch chain connecting rod I31 is connected to the top end of the third branch chain connecting rod II32 through the third branch chain prismatic pair 35; the end of the third branch chain connecting rod II32 is connected to a corresponding fixed hinge support on the fixed platform 5 through the third branch chain revolute pair 33. Among them, the moving direction of the third branch chain prismatic pair 35 is perpendicular to the rotation axis of the third branch chain revolute pair 33 and passes through the center of the sphere of the third branch chain spherical pair 34.

[0032] The mechanism contains a total of three prismatic pairs, namely a first branch chain prismatic pair I115, a first branch chain prismatic pair II116 and a third branch chain prismatic pair 35.

[0033] The mechanism contains a total of eight revolute pairs, namely a first branch chain revolute pair I16, a first branch chain revolute pair II17, a first branch chain revolute pair III18, a first branch chain revolute pair IV19, a first branch chain revolute pair V110, a second branch chain revolute pair I23, a second branch chain revolute pair II24 and a third branch chain revolute pair 33.

[0034] Among them, the second branch chain revolute pair II24, the third branch chain prismatic pair 35, the first branch chain prismatic pair I115 and the first branch chain prismatic pair II116 serve as driving pairs, that is, a total of four driving pairs are included, and the four driving pairs drive the moving platform 4 to realize the movement and mutual switching between the spatial two-translation working mode and the one-translation one-rotation working mode relative to the fixed platform 5.

[0035] When the first sliding hinge support 113 and the second sliding hinge support 114 achieve collinear rotation axes through the slide rail 51 on the fixed platform 5, the mechanism enters the one-translation one-rotation working mode, as Figure 3 shown; when the first sliding hinge support 113 and the second sliding hinge support 114 are separated and fixed on both sides so that the first branch chain connecting rod IV14 and the first branch chain connecting rod V15 are parallel, the mechanism enters the two-translation working mode, as Figure 2 shown; the two modes do not interfere with each other and no singular configurations will occur.

[0036] Matters not described in detail in this invention are all well-known technologies.

[0037] The embodiments described above are only used to describe 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 should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A metamorphic parallel mechanism with two modes of 2T and 1T1R, 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 connected between the moving platform and the fixed platform; the second branch chain and the third branch chain are symmetrically arranged with respect to the first branch chain; The first branch chain includes five revolute pairs and two Hooke's joints from the moving platform to the fixed platform. Two of the revolute pairs and two Hooke's joints form a parallelogram configuration, and the two revolute pairs in this parallelogram configuration are respectively connected to the corresponding prismatic pairs on the fixed platform; The second branch chain includes two revolute pairs and a second branch chain C pair in sequence from the moving platform to the fixed platform; The third branch chain includes a spherical pair, a prismatic pair, and a revolute pair in sequence from the moving platform to the fixed platform; The fixed platform is of a rectangular structure, and two parallel prismatic rails are provided at positions corresponding to the two revolute pairs at the bottom of the first branch chain, and fixed hinge supports are provided at positions corresponding to the second branch chain and the third branch chain; the moving platform is of an isosceles triangle structure, and a spherical pair hinge support corresponding to the third branch chain and a revolute pair hinge support corresponding to the second branch chain are respectively installed at the positions of the two symmetric base angles, and a revolute pair hinge support corresponding to the first branch chain is installed at the position of the top angle; the axis of rotation of the revolute pair hinge support is parallel to the moving platform; the axis of rotation of the revolute pair hinge support is perpendicular to the moving platform; The first branch chain includes a first sliding hinge support, a second sliding hinge support, a first branch chain link I, a first branch chain link II, a first branch chain link III, a first branch chain link IV, a first branch chain link V, a first branch chain revolute pair I, a first branch chain revolute pair II, a first branch chain revolute pair III, a first branch chain revolute pair IV, a first branch chain revolute pair V, a first Hooke's joint, and a second Hooke's joint; the top end of the first branch chain link I is connected to the corresponding revolute pair hinge support on the moving platform through the first branch chain revolute pair I; the top end of the first branch chain link II is connected to the end of the first branch chain link I through the first branch chain revolute pair II; the end of the first branch chain link II is connected to the middle of the upper end of the first branch chain link III through the first branch chain revolute pair III; the left and right ends of the first branch chain link III are respectively connected to the first branch chain link IV and the first branch chain link V through the first Hooke's joint and the second Hooke's joint to form a parallelogram configuration; the end of the first branch chain link IV is connected to the first sliding hinge support through the first branch chain revolute pair IV; the end of the first branch chain link V is connected to the second sliding hinge support through the first branch chain revolute pair V; the first sliding hinge support and the second sliding hinge support are respectively connected to the corresponding prismatic rails on the fixed platform; The axis direction of the first branch chain revolute pair I is perpendicular to the axis directions of the first branch chain revolute pair II and the first branch chain revolute pair III; the first branch chain link III, the first branch chain link IV, and the first branch chain link V form a closed-loop parallelogram configuration through the first Hooke's joint and the second Hooke's joint; the first sliding hinge support and the second sliding hinge support are connected through the prismatic rail pair on the fixed platform to achieve collinear rotation axes; The second branch chain includes a second branch chain link I, a second branch chain link II, a second branch chain revolute pair I, a second branch chain revolute pair II, and a second branch chain C pair; the top end of the second branch chain link I is connected to a corresponding revolute pair hinge support on the moving platform through the second branch chain revolute pair I; the end of the second branch chain link I is connected to the top end of the second branch chain link II through the second branch chain revolute pair II; the end of the second branch chain link II is connected to a corresponding fixed hinge support on the fixed platform through the second branch chain C pair; The axes of rotation of the two revolute pairs in the second branch chain are parallel to the axis of rotation of the second branch chain C pair; The third branch chain includes a third branch chain link I, a third branch chain link II, a third branch chain revolute pair, a third branch chain spherical pair, and a third branch chain prismatic pair; the top end of the third branch chain link I is connected to a corresponding spherical pair hinge support on the moving platform through the third branch chain spherical pair; the end of the third branch chain link I is connected to the top end of the third branch chain link II through the third branch chain prismatic pair; the end of the third branch chain link II is connected to a corresponding fixed hinge support on the fixed platform through the third branch chain revolute pair; The direction of motion of the third branch chain prismatic pair is perpendicular to the axis of rotation of the third branch chain revolute pair and passes through the center of the sphere of the third branch chain spherical pair; The second branch chain revolute pair II, the third branch chain prismatic pair, the first branch chain prismatic pair I, and the first branch chain prismatic pair II serve as driving pairs, that is, a total of four driving pairs, and the four driving pairs drive the moving platform to realize the motion and mutual switching between the spatial two-translation working mode and the one-translation one-rotation working mode relative to the fixed platform; When the first sliding hinge support and the second sliding hinge support achieve collinear axes of the revolute pairs through the slide rail on the fixed platform, the mechanism enters the one-translation one-rotation working mode; when the first sliding hinge support and the second sliding hinge support are separated and fixed on both sides so that the first branch chain link IV and the first branch chain link V are parallel, the mechanism enters the two-translation working mode.

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