CN112338902A - Four-degree-of-freedom decoupling parallel mechanism - Google Patents
Four-degree-of-freedom decoupling parallel mechanism Download PDFInfo
- Publication number
- CN112338902A CN112338902A CN202011329650.2A CN202011329650A CN112338902A CN 112338902 A CN112338902 A CN 112338902A CN 202011329650 A CN202011329650 A CN 202011329650A CN 112338902 A CN112338902 A CN 112338902A
- Authority
- CN
- China
- Prior art keywords
- connecting rod
- pair
- moving
- cylindrical
- branch
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J9/00—Program-controlled manipulators
- B25J9/003—Program-controlled manipulators having parallel kinematics
Landscapes
- Engineering & Computer Science (AREA)
- Robotics (AREA)
- Mechanical Engineering (AREA)
- Transmission Devices (AREA)
Abstract
本发明公开了一种四自由度解耦并联机构，本机构由三个支链组成，每个支链包括两个移动副和两个转动副共四个运动副，动平台可以有两平动和两转动四个自由度。机构结构的耦合度为0，即具有结构解耦特性，可以容易地计算机构的解析正解，从而有利于进行机构的工作空间分析及动力学分析等；机构动平台运动旋量的每一个分量的值都是只由一个驱动副决定，即具有运动学解耦特性，该特性有利于降低运动控制的难度和提高机构的控制精度。本发明具有机构分析和控制难度均较低、工作空间大，刚度高、装配容易的优点。可以用于分拣、装配、喷涂、加工和3D打印等场合。
The invention discloses a decoupling parallel mechanism with four degrees of freedom. The mechanism is composed of three branch chains, each branch chain includes two moving pairs and two rotating pairs, a total of four moving pairs, and the moving platform can have two translational motion pairs. and two rotations with four degrees of freedom. The coupling degree of the mechanism structure is 0, that is, it has the characteristics of structural decoupling, and the analytical positive solution of the mechanism can be easily calculated, which is conducive to the work space analysis and dynamic analysis of the mechanism. The value is only determined by one driving pair, that is, it has the characteristic of kinematic decoupling, which is beneficial to reduce the difficulty of motion control and improve the control accuracy of the mechanism. The invention has the advantages of lower difficulty in mechanism analysis and control, large working space, high rigidity and easy assembly. It can be used for sorting, assembly, spraying, processing and 3D printing.
Description
Technical Field
The invention relates to a parallel mechanism, in particular to a four-degree-of-freedom parallel mechanism capable of realizing two movements and two rotations.
Background
The parallel mechanism has the advantages of compact structure, high rigidity, strong bearing capacity, small accumulated error and the like, but the general structure has high coupling degree, is difficult to obtain the positive solution of the mechanism, and has high kinematic coupling and complex kinematic control.
Most of the existing four-degree-of-freedom parallel mechanisms cannot simultaneously have two characteristics of motion decoupling and structure decoupling. Patent application No. 201510387578.1 proposes a two-movement two-rotation complete decoupling mechanism, which realizes motion decoupling, but the coupling degree of the structure is higher, and the difficulty of solving the positive solution is higher. And the axes of 8 revolute pairs are required to be converged at one point, so that the assembly difficulty is high. Patent application No. 201610141778.3 proposes a three-translation one-rotation parallel manipulator, which has a low degree of structural coupling, but does not achieve complete structural decoupling and motion decoupling.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, provides a four-degree-of-freedom parallel mechanism which has the characteristics of structural decoupling and motion decoupling, and has the advantages of lower mechanism analysis and control difficulty, large working space, high rigidity and easy assembly.
The invention relates to a four-degree-of-freedom decoupling parallel mechanism which comprises three static platforms, a first branched chain, a second branched chain, a third branched chain and a movable platform, the three static platforms are all fixed, the first branched chain, the second branched chain and the third branched chain respectively comprise a U-shaped connecting rod and an L-shaped connecting rod, a static platform sliding groove is formed in one end of the L-shaped connecting rod, the middle of the other end of the L-shaped connecting rod is fixedly connected with one end of the connecting rod, a connecting rod chute is arranged in the lower flange plate of the U-shaped connecting rod, a side rod section of the static platform is connected in the static platform chute of the L-shaped connecting rod in a sliding way, the static platform and the static platform sliding groove form a first sliding pair, the other end of the connecting rod is inserted into the connecting rod sliding groove of the U-shaped connecting rod to form a second sliding pair, so that the L-shaped connecting rod is in sliding connection with the U-shaped connecting rod, and the sliding direction of the first sliding pair is perpendicular to that of the second sliding pair;
the bottom wall of the movable platform is connected with a left support and a right support at left and right intervals, the left support and the right support respectively comprise support plates arranged at left and right intervals, the top wall of each support plate is fixedly connected with the bottom wall of the movable platform, the square head end of a square head cylindrical connecting rod is arranged between the left support plate and the right support plate of the right support, the upper end of a perforated cylindrical rod is arranged between the left support plate and the right support plate of the left support, the left side of a rotating shaft penetrates through the left support plate and the right support plate of the left support and the upper end of the perforated cylindrical rod, the right side of the rotating shaft penetrates through the left support plate and the right support plate of the right support and the square head cylindrical connecting rod, nuts are connected with the left end and the right end of the rotating shaft, the perforated cylindrical rod is rotatably connected with the rotating shaft to;
the lower side of the square-head cylindrical connecting rod is connected with the upper flange plate of the U-shaped connecting rod of the first branched chain through a third rotating pair, the lower part of the cylindrical rod with the hole is coaxially and rotatably connected with the upper end of one cylindrical connecting rod through a sixth rotating pair, the lower end of the cylindrical connecting rod is sequentially connected with the upper flange plate of the third branched chain and the upper flange plate of the second branched chain through a fifth rotating pair and a fourth rotating pair from top to bottom respectively in a rotating manner, and the rotating axis of the third rotating pair is perpendicular to that of the second rotating pair;
the planes of the first moving pair and the second moving pair of each branched chain are parallel to the horizontal plane, the moving direction of the first moving pair on the third branched chain is perpendicular to the moving direction of the first moving pair on the second branched chain, and the rotating axis of the first rotating pair is perpendicular to the rotating axis of the sixth rotating pair.
The invention has the following advantages:
the mechanism has two translational motions and two rotational motions with four degrees of freedom, a topological structure of the mechanism is decomposed into a plurality of single open chains according to an orientation feature set theory, and the coupling degree of the mechanism structure is further analyzed to be 0 according to the relationship between the degree of freedom of the mechanism and the degree of freedom of a kinematic pair (excluding a local degree of freedom), the number of driving pairs and the number of independent displacement equations of ordered single open chains which can be listed, so that the mechanism has a structural decoupling characteristic, the analytical forward solution of the mechanism can be easily calculated, and the mechanism is favorable for working space analysis, kinetic analysis and the like; according to the momentum theory, in any branch from the static platform to the movable platform, if a certain component of the momentum of a certain driving joint is not zero, the corresponding components of the momentum of other joints are all zero; in all the driving joint rotations, if a component of a certain driving rotation is not zero, corresponding components of other driving joint rotations are all zero. Therefore, each component of the motion vector of the mechanism moving platform is determined by only one driving joint, and the mechanism moving platform has a kinematic decoupling characteristic which is beneficial to reducing the difficulty of motion control and improving the control precision of the mechanism. The invention can form a three-movement two-rotation series-parallel mixing mechanism by connecting a small mechanism with a movement freedom degree in series at the tail end of the movable platform, wherein the movement freedom degree is vertical to the two translation directions of the parallel mechanism, and the three-movement two-rotation series-parallel mixing mechanism is used for occasions such as sorting, assembling, spraying, processing and 3D printing.
Drawings
FIG. 1 is a schematic structural diagram of a four-DOF parallel mechanism according to the present invention;
FIG. 2 is a schematic perspective view of a first branch of the structure shown in FIG. 1;
FIG. 3 is a schematic view of an L-shaped link in the configuration shown in FIG. 1;
FIG. 4 is a schematic view of a perforated cylindrical bar pivotally connected to a left support in the configuration shown in FIG. 1;
FIG. 5 is a schematic view of a cylindrical rod in rotatable connection with the perforated cylindrical rod of the configuration shown in FIG. 4;
fig. 6 is a diagrammatic view of the moving platform of the structure shown in fig. 1.
Detailed Description
The following embodiments are provided to illustrate the present invention, but are not intended to limit the scope of the present invention.
As shown in the attached drawings, the four-degree-of-freedom parallel mechanism comprises three static platforms 1, a first branched chain 2, a second branched chain 3, a third branched chain 4 and a movable platform 6, wherein the three static platforms 1 are all fixed.
The first branched chain 2, the second branched chain 3 and the third branched chain 4 respectively comprise a U-shaped connecting rod 10 and an L-shaped connecting rod 8, wherein a fixed platform sliding groove is formed in one end of the L-shaped connecting rod 8, the middle of the other end of the L-shaped connecting rod 8 is fixedly connected with one end of the connecting rod, and a connecting rod sliding groove is formed in the lower flange plate of the U-shaped connecting rod. A side rod section of the static platform 1 is connected in a sliding mode in a static platform sliding groove of the L-shaped connecting rod 8, the static platform 1 and the static platform sliding groove form a first sliding pair 7, and the other end of the connecting rod is inserted into a connecting rod sliding groove of the U-shaped connecting rod 10 to form a second sliding pair 9, so that the L-shaped connecting rod 8 and the U-shaped connecting rod 10 are connected in a sliding mode. The sliding direction a of the first moving pair 7 and the sliding direction b of the second moving pair 9 are perpendicular to each other.
A left support 14 and a right support 13 are connected on the bottom wall of the movable platform 6 at intervals from left to right, the left support 14 and the right support 13 both comprise support plates arranged at left and right intervals, the top wall of each support plate is fixedly connected with the bottom wall of the movable platform 6, the square head end of a square head cylindrical connecting rod 12 is arranged between the left and right support plates of the right support 13, the upper end of a perforated cylindrical rod 5 is arranged between the left and right support plates of the left support 14, the left side of a rotating shaft passes through the left and right support plates of the left support 14 and the upper end of the perforated cylindrical rod 5, and the right side of the rotating shaft passes through the left and right support plates of the right support 13 and the square head end of the square head cylindrical connecting rod 12, the left end and the right end of the rotating shaft are connected with nuts, the cylindrical rod 5 with the hole is rotationally connected with the rotating shaft to form a first rotating pair, and the square-head cylindrical connecting rod 12 is rotationally connected with the rotating shaft to form a second rotating pair.
The lower side of the square-head cylindrical connecting rod 12 is connected with the upper flange plate of the U-shaped connecting rod of the first supporting chain 2 through a third rotating pair 11, the lower part of the perforated cylindrical rod 5 is coaxially and rotatably connected with the upper end of a cylindrical connecting rod 15 through a sixth rotating pair 18, as an embodiment of the invention, the structure of the sixth rotating pair 18 can comprise a bearing mounting hole formed in the middle of the bottom wall of the perforated cylindrical rod 5, a bearing is mounted in the bearing mounting hole, and the upper end of the cylindrical connecting rod 15 is fixedly connected with an inner ring of the bearing.
The lower end of the cylindrical connecting rod 15 is connected with the upper flange plate of the third branched chain 4 and the upper flange plate of the second branched chain 3 from top to bottom in sequence through a fifth revolute pair and a fourth revolute pair respectively.
As an embodiment of the present invention, the third revolute pair 11, the fourth revolute pair, and the fifth revolute pair are bearing structures, the bearing structures include bearing mounting holes respectively formed at an end of an upper flange plate of the U-shaped link of the first branch chain 2, an end of an upper flange plate of the U-shaped link of the second branch chain 3, and an end of an upper flange plate of the U-shaped link of the third branch chain 4, bearings are mounted in the bearing mounting holes, a lower side of the square-head cylindrical link 12 passes through a bearing inner ring on the first branch chain 2, the cylindrical link 15 sequentially passes through a bearing inner ring on the third branch chain 4 and a bearing inner ring on the second branch chain 3 from top to bottom, and the cylindrical link, the U-shaped link of the second branch chain 3, and the U-shaped link of the third branch chain 4 are connected by the fourth revolute pair 16 and the fifth revolute pair 17, respectively.
The rotation axis c of the third revolute pair 11 is perpendicular to the rotation axis d of the second revolute pair 13.
The planes of the first and second sliding pairs 7, 9 of the respective branches are parallel to the horizontal plane, and the moving direction g of the first sliding pair 7 on the third branch 4 is perpendicular to the moving direction e of the first sliding pair 7 on the second branch 3. The rotation axis d of the first revolute pair and the rotation axis f of the sixth revolute pair 18 are perpendicular to each other.
The driving pairs are a second rotating pair 13, a first moving pair 7 on the second branched chain 3, a first moving pair 7 on the third branched chain 4 and a sixth rotating pair 18. The rotating shaft is driven to drive the movable platform 6 to rotate so as to realize the rotation of the second revolute pair 13, the L-shaped connecting rod 8 is driven to enable the connecting rod 8 on the second branched chain 3 to move along the e direction so as to realize the movement of the first moving pair 7 on the second branched chain 3, and the L-shaped connecting rod 8 is driven to enable the connecting rod 8 on the third branched chain 4 to move along the g direction so as to realize the movement of the first moving pair 7 on the third branched chain 4. The sixth revolute pair 18 drives the perforated cylindrical rod 5 to rotate around the f-axis through driving the cylindrical connecting rod 15 to rotate, so that the sixth revolute pair 18 rotates.
(1) The structural decoupling of the parallel mechanism is discussed:
according to the theory of the orientation feature set,
wherein
Δj- -the jth single open-chain SOC in BKCjDegree of constraint of
fiOf the ith kinematic pairDegree of freedom
mj- - (th) socjNumber of pairs of movements Ij- - (th) socjNumber of driving pairs
The degree of coupling of the basic kinematic chain BKC is defined as:
wherein min {. means that BKC is decomposed into v SOCs (Delta)j) There are many decomposition schemes, which should be taken
The minimum SOC allocation scheme.
The first single open chain of the invention is composed of two sliding pairs of the second branch chain 3 and two sliding pairs of the third branch chain 4, SOC1T { -T ≠ T { [ T ] T { [ T ] T }, having four mobile joints,
wherein two drive pairs are respectively a first moving pair 7 of the second branched chain 3 and a first moving pair 7 of the third branched chain 4, I1Two translational displacements are generated, the first single open chain can get two equations for the translational displacement,
the degree of constraint Δ of the first single open chain1When the value is 0, the two sliding joints of the second sliding pair 9 of the second branch chain 3 and the second sliding pair 9 of the third branch chain 4 can be released.
Similarly, the second single-open chain is composed of the sixth revolute pair 18, the first revolute pair 14, the second revolute pair 13, the third revolute pair 11 and two revolute pairs of the first branch chain 2, and the SOC2{-R⊥R|R⊥R⊥T⊥T}，
The rotation angle of the driving pair cylindrical connecting rod 15 and the rotation angle of the second rotating pair 13 are known, I2The rotation angle of the third rotating pair 11 is determined by the rotation angle of the cylindrical connecting rod 15, the rotation angle of the first rotating pair is the same as that of the second rotating pair, the two moving pairs are determined by the two driving moving pairs in the first single open chain,
the degree of constraint Δ of the second single open chain2All joints can be solved as 0. In summary, in the parallel mechanism, when the driving pairs are the second revolute pair 13, the sixth revolute pair 18, the first revolute pair 7 of the second branched chain 3, and the first revolute pair 7 of the third branched chain 4, respectively, the coupling degree k of the present invention is zero, all passive joints can be solved, and an analytic positive solution of the parallel mechanism can be obtained.
(2) The motion decoupling of the parallel mechanism is discussed:
according to the theory of helicity: the four driving pairs are respectively a first moving pair 7 of the second branched chain 3, a first moving pair 7 of the third branched chain 4, a second rotating pair 13 and a sixth rotating pair 18.
Assuming that the origin of coordinates is at the intersection of the axis d of the second revolute pair 13 and the axis f of the sixth revolute pair 18, the x-axis is parallel to the moving direction e of the first revolute pair 7 of the second branched chain 3, and the y-axis is parallel to the moving direction g of the first revolute pair 7 of the third branched chain 4.
Rotating amount of moving platform
$P＝(α β γ x y z)T
Driving pair rotation angle
θ＝(θ1 θ1 θ3 θ4 0 0)T
Wherein
Dependent movement of one of alpha, beta being the other
i represents the first and the secondA three-branched chain; $ fit for the treatment of diabetes1,i $2,i $3,i $4,iThe motion rotation amounts of all joints of the ith branched chain are respectively,
respectively represents the movement speed of each joint of the ith branch chain
Wherein:
$a,2＝[0 0 1 0 0 0]
$a,3＝[0 0 0 1 0 0]
$a,4＝[0 0 0 0 1 0]
Jc＝[$c,1 T $c,2 T]Unit restraint rotation force rotation quantity provided for branched chain i to moving platform
$c,1 T＝[0 0 0 0 0 1]
Formula (1) two-side co-multiplication JxIs finished to obtain
Wherein Jθ＝Jx($1,i $2,i $3,i $4,i 0 0)
Formula (2) two sides are multiplied by Jx -1To obtain
Wherein J is Jx -1Jθ
The motion decoupling is realized by determining one motion output component of the movable platform by only one driving input.
The device can realize two rotations and two translation, and the two rotations are respectively along the rotation axis d of the second rotating pair 13 and the rotation axis f of the sixth rotating pair 18. The two translations are respectively along the moving direction e of the first moving pair 7 of the second branched chain and the moving direction g of the first moving pair 7 of the third branched chain.
The above-mentioned embodiments are only for illustrating the technical ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and to carry out the same, and the present invention shall not be limited to the embodiments, i.e. the equivalent changes or modifications made within the spirit of the present invention shall fall within the scope of the present invention.
Claims (1)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011329650.2A CN112338902A (en) | 2020-11-24 | 2020-11-24 | Four-degree-of-freedom decoupling parallel mechanism |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011329650.2A CN112338902A (en) | 2020-11-24 | 2020-11-24 | Four-degree-of-freedom decoupling parallel mechanism |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN112338902A true CN112338902A (en) | 2021-02-09 |
Family
ID=74364692
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202011329650.2A Withdrawn CN112338902A (en) | 2020-11-24 | 2020-11-24 | Four-degree-of-freedom decoupling parallel mechanism |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112338902A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113319829A (en) * | 2021-07-07 | 2021-08-31 | 天津大学 | High-rigidity motion decoupling three-translation parallel mechanism |
-
2020
- 2020-11-24 CN CN202011329650.2A patent/CN112338902A/en not_active Withdrawn
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113319829A (en) * | 2021-07-07 | 2021-08-31 | 天津大学 | High-rigidity motion decoupling three-translation parallel mechanism |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN105729450B (en) | Four-freedom parallel mechanism | |
| Angeles | The qualitative synthesis of parallel manipulators | |
| CN104626099A (en) | Completely-decoupled three-rotating three-moving six-freedom-degree parallel-serial mechanism | |
| CN108555889A (en) | The space five-freedom series-parallel connection process unit and its application method of redundant bondage | |
| CN200951497Y (en) | Two-D moving and two-D rotation parallel platform mechanism | |
| CN1586807A (en) | Three freedom redundancy parallel mechanism for realizing two dimension translation and one dimension rotation | |
| CN204976628U (en) | Five degree of freedom industrial robot | |
| CN107553470A (en) | Parallel institution and its expansion multi-axis linkages with five degree of freedom | |
| CN205588291U (en) | Four degree of freedom parallel mechanism | |
| CN107498541A (en) | A kind of two translations one rotate 3-freedom parallel mechanism | |
| CN110653797B (en) | A three-degree-of-freedom pneumatic translation parallel mechanism | |
| Kiselev et al. | Parallel robots with a circular guide: Systematic review of kinematic schemes and methods of synthesis and analysis | |
| CN102626920A (en) | Non-concurrent axis symmetric three-dimensional-rotation parallel mechanism with two-degree of freedom planar subchains | |
| CN109304703A (en) | A three-translation parallel mechanism operator with zero coupling degree | |
| CN104875188A (en) | (2T1R)&(2R) Completely isotropic parallel serial robot mechanism | |
| CN100411826C (en) | A four-degree-of-freedom parallel robot mechanism with two-dimensional translation and two-dimensional rotation | |
| CN109571444B (en) | A Partially Decoupled Parallel Mechanism with Two Translations and One Rotation | |
| Uchiyama | Structures and characteristics of parallel manipulators | |
| CN105643593A (en) | (3T)&2R five-degree-of-freedom decoupling parallel-series connection mechanism | |
| CN106272362B (en) | A kind of four-degree-of-freedom robot mechanism of achievable complete cycle revolution | |
| CN102114599A (en) | Decoupling three-rotation parallel mechanism for imaginary axis lathe and robot | |
| CN105619383B (en) | A kind of three one rotating parallel device people's platforms of translation of the kinematic pair moving platform of weak coupling two | |
| Enferadi et al. | A novel approach for forward position analysis of a double-triangle spherical parallel manipulator | |
| CN100348378C (en) | Three freedom degrees decoupling sphere parallel mechanism | |
| CN214238227U (en) | Four-degree-of-freedom decoupling parallel mechanism |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| WW01 | Invention patent application withdrawn after publication |
Application publication date: 20210209 |
|
| WW01 | Invention patent application withdrawn after publication |