CN108297070B - Three-freedom parallel mechanism - Google Patents
Three-freedom parallel mechanism Download PDFInfo
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- CN108297070B CN108297070B CN201711418392.3A CN201711418392A CN108297070B CN 108297070 B CN108297070 B CN 108297070B CN 201711418392 A CN201711418392 A CN 201711418392A CN 108297070 B CN108297070 B CN 108297070B
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- connecting rod
- branched chain
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- spherical hinge
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J9/00—Programme-controlled manipulators
- B25J9/003—Programme-controlled manipulators having parallel kinematics
- B25J9/0054—Programme-controlled manipulators having parallel kinematics with kinematics chains having a spherical joint at the base
Abstract
The invention provides a three-degree-of-freedom parallel mechanism which comprises a fixed platform, a movable platform and three moving branched chains, wherein at least one of the moving branched chains is a flexible branched chain; the flexible branched chain comprises a first connecting rod, a second connecting rod and an axis variable revolute pair, the axis variable revolute pair comprises a fixed component, a movable component and a spherical hinge pair, one end of the fixed component is fixedly arranged on the fixed platform, the other end of the fixed component is matched and attached to the inclined surface of the movable component, the spherical hinge pair is contained in the fixed component, the spherical hinge connecting rod of the spherical hinge pair penetrates out of the movable component, the first connecting rod is respectively and rotatably connected with the spherical hinge connecting rod and the second connecting rod, and the second connecting rod is connected with the spherical hinge of the movable platform. The variable-axis revolute pair is fused in the structure of the moving branched chain, so that the force and moment transmission of the moving branched chain is facilitated, and the singular configuration of a parallel mechanism can be effectively avoided.
Description
Technical Field
The invention belongs to the field of machinery, and particularly relates to a three-degree-of-freedom parallel mechanism.
Background
Since the parallel robot is proposed for the first time in 1938, the parallel robot has the characteristics of higher rigidity, stronger bearing capacity, small error, high precision, small dead weight-load ratio, good dynamic performance, easiness in control and the like, and is widely applied to various social fields. At present, the 2-degree-of-freedom, 3-degree-of-freedom, 4-degree-of-freedom and 6-degree-of-freedom parallel mechanisms are common, and the three-degree-of-freedom parallel mechanisms are the least-degree-of-freedom parallel mechanisms which are most researched and most widely applied, and can be divided into four types according to the types of the degrees of freedom of a moving platform: 3 rotating parallel mechanism, 2 rotating 1 moving parallel mechanism, 1 rotating 2 moving parallel mechanism and 3 moving parallel mechanism.
An ankle joint rehabilitation robot (CN200810052248.7) is proposed by Liuji professor and the like at Hebei university of industry, the model of the ankle joint rehabilitation robot is consistent with the models of Zhao iron stone at Yanshan university and the ankle joint rehabilitation robot proposed by Daiheng at London university, and both are 3-RSS/S type three-degree-of-freedom parallel mechanisms. The parallel mechanism is provided with four moving branch chains, wherein the lower end of the middle moving branch chain is fixed on a fixed platform, the upper end of the middle moving branch chain is connected with the center of a moving platform by adopting a spherical hinge, the other three moving branch chains are uniformly distributed along the circumferential direction, one end of a driving connecting rod is connected with the fixed platform by adopting a revolute pair, the other end of the driving connecting rod is connected with a driven connecting rod by adopting a spherical hinge pair, and one end of the driven connecting rod is connected with the moving platform by adopting a spherical; the mechanism can rotate around the center of a spherical hinge of the middle motion branched chain in three degrees of freedom.
The Wang Yongfeng et al of Shenzhen advanced technology research institute proposes an ankle joint rehabilitation robot (CN102631275A), and the parallel mechanism is a 3- (HS) S/S type three-degree-of-freedom parallel mechanism. The parallel mechanism is also provided with four moving branch chains, wherein the lower end of the middle moving branch chain is fixed on the fixed platform, the upper end of the middle moving branch chain is connected with the center of the moving platform by adopting a spherical hinge, the three moving branch chains are uniformly distributed along the circumferential direction, the bottom end of the middle moving branch chain is connected with the fixed platform by adopting a spiral pair, and the included angle between the axis of the spiral pair and the fixed platform can be adjusted; in addition, one end of the support connecting rod is connected with the sliding block on the screw pair through a spherical hinge, and the other end of the support connecting rod is connected with the movable platform through a spherical hinge; the mechanism can rotate around the center of a spherical hinge of the middle motion branched chain in three degrees of freedom.
In the three-degree-of-freedom parallel mechanisms, the kinematic pairs of the branched chains all adopt kinematic pairs in a standard form, and if the axes of the revolute pairs are always fixed and invariable in the motion process, the transmission of force and moment of the kinematic branched chains is not facilitated; in addition, the kinematic pair in the standard form cannot easily avoid the singular configuration of the mechanism because the motion axis of the kinematic pair is fixed.
Disclosure of Invention
The embodiment of the invention relates to a three-degree-of-freedom parallel mechanism which can at least solve part of defects in the prior art.
The embodiment of the invention relates to a three-degree-of-freedom parallel mechanism which comprises a fixed platform and a movable platform, wherein the fixed platform is connected with the movable platform through a first moving branched chain, a second moving branched chain and a third moving branched chain which are connected in parallel; the flexible branched chain comprises a first connecting rod, a second connecting rod and an axis variable revolute pair, wherein the axis variable revolute pair comprises a fixed component, a movable component and a spherical hinge pair, one end of the fixed component is fixedly installed on the fixed platform, the other end of the fixed component is matched with the inclined plane of the movable component to be attached to the inclined plane of the movable component, the spherical hinge pair is contained in the fixed component, the spherical hinge connecting rod of the spherical hinge pair penetrates out of the movable component, the first connecting rod is respectively connected with the spherical hinge connecting rod and the second connecting rod in a rotatable mode, and the second connecting rod is connected with the spherical hinge of the movable platform.
As one embodiment, the connection points of the first moving branched chain, the second moving branched chain and the third moving branched chain are flexible branched chains, and the connection points of the moving platform and the three second connecting rods are annularly arranged on the moving platform.
As one embodiment, the three-degree-of-freedom parallel mechanism further comprises a middle connecting rod, wherein one end of the middle connecting rod is fixed on the fixed platform, and the other end of the middle connecting rod is connected with the movable platform through a spherical hinge.
In one embodiment, the first moving branch chain, the second moving branch chain and the third moving branch chain are connected and arranged around the intermediate link along the circumferential direction of the moving platform.
In one embodiment, each of the flexible branched chains is connected to a driving unit, and the driving unit is connected to the corresponding first link or the second link.
In one embodiment, the fixed member and the movable member are assembled into a cylindrical structure when the axes of the fixed member and the movable member are coincident.
The embodiment of the invention at least has the following beneficial effects:
in the flexible branched chain, when the first link drives the ball hinge link to rotate, the inclined plane of the movable member is limited to rotate on the inclined plane of the fixed member due to the action of the inclined plane, and the axis of the ball hinge link is changed in real time. Compared with a moving branched chain with a common rotating pair structure, the variable-axis rotating pair is fused in the structure of the moving branched chain, so that the force and moment transmission of the moving branched chain is facilitated, and the singular configuration of a parallel mechanism can be effectively avoided.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a three-degree-of-freedom parallel mechanism according to an embodiment of the present invention;
FIG. 2 is a schematic structural diagram of an axis-variable revolute pair provided in an embodiment of the present invention;
fig. 3 is a schematic usage state diagram of a three-degree-of-freedom parallel mechanism according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 1-3, this embodiment provides a three-degree-of-freedom parallel mechanism, which includes a fixed platform 1 and a movable platform 2, where the fixed platform 1 and the movable platform 2 are connected through a first moving branched chain, a second moving branched chain and a third moving branched chain that are connected in parallel, and it is easy to understand that one end of each of the three moving branched chains is connected to the movable platform 2, and the other end is connected to the fixed platform 1.
In the connection of the first moving branched chain, the second moving branched chain and the third moving branched chain, at least one of the moving branched chains is a flexible branched chain; the flexible branched chain comprises a first connecting rod 5, a second connecting rod 6 and an axis variable revolute pair 4, wherein the axis variable revolute pair 4 comprises a fixed component 41, a movable component 42 and a spherical hinge pair 43, one end of the fixed component 41 is fixedly installed on the fixed platform 1, the other end of the fixed component is matched and attached to the inclined surface of the movable component 42, the spherical hinge pair 43 is contained in the fixed component 41, the spherical hinge connecting rod 431 of the fixed component penetrates out of the movable component 42, the first connecting rod 5 is respectively in rotatable connection with the spherical hinge connecting rod 431 and the second connecting rod 6, and the second connecting rod 6 is in spherical hinge connection with the movable platform 2. The rotatable connection structure of the first connecting rod 5 and the spherical hinge connecting rod 431 and the rotatable connection structure of the first connecting rod 5 and the second connecting rod 6 are common revolute pairs, the rotating shafts of the two rotatable connection structures are generally parallel to each other, wherein the connecting rotating shaft of the first connecting rod 5 and the spherical hinge connecting rod 431 is the axis of the spherical hinge connecting rod 431; preferably, when the hinge axis direction of the spherical hinge connection structure of the second link 6 and the movable platform 2 is perpendicular to the movable platform 2, the rotation axis direction of the two rotatable connection structures corresponding to the first link 5 is also perpendicular to the movable platform 2. The fixed member 41 and the movable member 42 are in a slope fit structure, that is, one end of the fixed member 41 away from the fixed platform 1 has a slope, one end of the movable member 42 away from the first link 5 also has a slope, and the two slopes are adapted to be capable of being attached to each other; easily understood, in order to facilitate the free motion of the three-degree-of-freedom parallel mechanism, the two inclined planes are both planes, and both the two inclined planes and the fixed platform 1 form an included angle. The fixed member 41 and the movable member 42 are preferably hollow members, so that the ball joint pair 43 can be accommodated therein, specifically, as shown in fig. 2, a ball socket of the ball joint pair 43 is accommodated in the fixed member 41, a ball head of the ball joint pair 43 is engaged with the ball socket, the ball joint link 431 is connected to the ball head, and the end of the movable member 42 away from the fixed member 41 penetrates through the hollow inner cavity of the movable member 42; preferably, the fixed member 41 and the movable member 42 are both cylindrical members, the ball and socket is preferably coaxially disposed with the fixed member 41, and the ball joint link 431 is preferably coaxially disposed with the movable member 42. Further preferably, the fixed member 41 and the movable member 42 are assembled into a cylindrical structure when the axes are coincident.
When the first link 5 drives the ball pivot link 431 to rotate, the inclined plane of the movable member 42 is limited to rotate on the inclined plane of the fixed member 41 due to the action of the inclined plane, and the axis of the ball pivot link 431 is changed in real time; the angle of this change in axis is related to the angle of inclination of the ramp. Compared with a moving branched chain with a common rotating pair structure, the variable-axis rotating pair is fused in the structure of the moving branched chain, so that the force and moment transmission of the moving branched chain is facilitated, and the singular configuration of a parallel mechanism can be effectively avoided.
As a preferred embodiment, as shown in fig. 1 and 3, the connections of the first moving branched chain, the second moving branched chain and the third moving branched chain are all flexible branched chains, and the connection points of the moving platform 2 and the three second connecting rods 6 are annularly arranged on the moving platform 2, so that the three-degree-of-freedom parallel mechanism with the structure operates more stably and reliably.
Further preferably, as shown in fig. 1 and 3, the three-degree-of-freedom parallel mechanism further includes an intermediate connecting rod 3, one end of the intermediate connecting rod 3 is fixed on the fixed platform 1, and the other end of the intermediate connecting rod 3 is connected with the movable platform 2 through a spherical hinge. Preferably, the first moving branch chain, the second moving branch chain and the third moving branch chain are connected and arranged around the middle connecting rod 3 along the circumferential direction of the moving platform 2, and the moving platform 2 can rotate around the center of a spherical hinge connected with the middle connecting rod 3 in three degrees of freedom. The three-degree-of-freedom parallel mechanism with the structure operates more stably and reliably; the three-degree-of-freedom parallel mechanism provided by the embodiment is a novel 3-RRRS/S type three-degree-of-freedom parallel mechanism, is simple in structure, stable and reliable in motion of the movable platform 2, good in force/torque transmission performance and high in flexibility, and can be applied to the fields of virtual axis machine tools, aviation simulation equipment, medical equipment and the like. In one embodiment, the movable platform 2 is a circular platform, and the center of the spherical hinge connected to the intermediate link 3 is preferably located on the central axis of the movable platform 2 (i.e. perpendicular to the axis of the movable platform 2).
As a preferred embodiment, as shown in fig. 1 and 3, each of the flexible branched chains is connected with a driving unit 7, and the driving unit 7 is connected with the corresponding first link 5 or the corresponding second link 6. The action of the driving unit 7 causes the relative position change between the first connecting rod 5 and the second connecting rod 6 and the axis change of the corresponding axis variable revolute pair 4, thereby driving the movable platform 2 to move. Preferably, the driving unit 7 may adopt a driving motor, which drives the rotating shaft between the first connecting rod 5 and the second connecting rod 6 to rotate, so as to drive the position of the first connecting rod 5 and the position of the second connecting rod 6 to change; as a possible embodiment, the driving motor may be a micro motor that is mounted on one of the links. The first moving branched chain, the second moving branched chain and the third moving branched chain are all in the structure of the flexible branched chain, and the required rotating action of the moving platform 2 can be realized through the cooperation of the three driving units 7.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (6)
1. The utility model provides a three degree of freedom parallel mechanism, includes and decides the platform and move the platform, decide the platform with move the platform and connect through parallelly connected first motion branched chain, second motion branched chain and third motion branched chain, its characterized in that: in the connection of the first moving branched chain, the second moving branched chain and the third moving branched chain, the first moving branched chain, the second moving branched chain and the third moving branched chain are all flexible branched chains;
the flexible branched chain comprises a first connecting rod, a second connecting rod and an axis variable revolute pair, wherein the axis variable revolute pair comprises a fixed component, a movable component and a spherical hinge pair, one end of the fixed component is fixedly installed on the fixed platform, the other end of the fixed component is matched with the inclined plane of the movable component to be attached to the inclined plane of the movable component, the spherical hinge pair is contained in the fixed component, the spherical hinge connecting rod of the spherical hinge pair penetrates out of the movable component, the first connecting rod is respectively connected with the spherical hinge connecting rod and the second connecting rod in a rotatable mode, and the second connecting rod is connected with the spherical hinge of the movable platform.
2. The three-degree-of-freedom parallel mechanism of claim 1, wherein: the connecting points of the movable platform and the three second connecting rods are annularly arranged on the movable platform.
3. The three-degree-of-freedom parallel mechanism of claim 1, wherein: the movable platform is characterized by further comprising a middle connecting rod, wherein one end of the middle connecting rod is fixed on the fixed platform, and the other end of the middle connecting rod is connected with the movable platform through a spherical hinge.
4. The three-degree-of-freedom parallel mechanism of claim 3, wherein: the first moving branched chain, the second moving branched chain and the third moving branched chain are arranged around the middle connecting rod along the circumferential direction of the moving platform.
5. The three-degree-of-freedom parallel mechanism of claim 1, wherein: each flexible branched chain is connected with a driving unit, and the driving unit is connected with the corresponding first connecting rod or the corresponding second connecting rod.
6. The three-degree-of-freedom parallel mechanism of claim 1, wherein: the fixed member and the movable member are spliced into a cylindrical structure when the axes of the fixed member and the movable member are overlapped.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201711418392.3A CN108297070B (en) | 2017-12-25 | 2017-12-25 | Three-freedom parallel mechanism |
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| CN201711418392.3A CN108297070B (en) | 2017-12-25 | 2017-12-25 | Three-freedom parallel mechanism |
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| CN108297070B true CN108297070B (en) | 2021-05-25 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109590209B (en) * | 2018-11-27 | 2021-10-08 | 江苏大学 | Three-degree-of-freedom parallel Chinese chestnut sieve |
| CN111331580B (en) * | 2020-03-17 | 2022-12-16 | 中国民航大学 | Six-degree-of-freedom parallel mechanism with turnable moving platform |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP3995449B2 (en) * | 2001-11-09 | 2007-10-24 | 三菱電機株式会社 | Parallel mechanism |
| CN103029121B (en) * | 2012-12-11 | 2014-11-12 | 燕山大学 | Three-degree-of-freedom parallel simulation platform with plane four-connecting rod closed loop structure |
| CN103070757B (en) * | 2013-01-08 | 2014-10-15 | 北京工业大学 | Parallel-type initiative/passive ankle rehabilitation training device |
| CN104706453B (en) * | 2015-03-25 | 2016-09-21 | 北京航空航天大学 | A kind of lower limb rehabilitation robot mechanism that can change between two kinds of configurations of 3URS and 2RRS/URS |
| JP2017035769A (en) * | 2015-08-13 | 2017-02-16 | アズビル株式会社 | Four degree-of-freedom mechanism |
| JP6284129B2 (en) * | 2015-09-17 | 2018-02-28 | 広島県 | Compliance device |
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