CN110539293B - Four-degree-of-freedom parallel mechanism - Google Patents
Four-degree-of-freedom parallel mechanism Download PDFInfo
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- CN110539293B CN110539293B CN201910976422.5A CN201910976422A CN110539293B CN 110539293 B CN110539293 B CN 110539293B CN 201910976422 A CN201910976422 A CN 201910976422A CN 110539293 B CN110539293 B CN 110539293B
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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
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Abstract
The invention provides a four-degree-of-freedom parallel mechanism, which comprises: the device comprises a fixed platform, a movable platform and three moving branched chains positioned between the fixed platform and the movable platform; each motion branch chain comprises a crank rocker mechanism, first arc-shaped rods and second arc-shaped rods, the crank rocker mechanism comprises a connecting rod, a first motor capable of moving along the axial direction of the connecting rod is mounted on the connecting rod, the axes of three first motor output shafts are intersected at one point in a space, one end of each first arc-shaped rod is connected with a revolute pair between movable platforms, the other end of each first arc-shaped rod is connected with a revolute pair at one end of each second arc-shaped rod, the other end of each second arc-shaped rod is connected with an output shaft of the first motor, the axes of the revolute pairs between the first arc-shaped rods and the movable platforms and the axes of the revolute pairs between the first arc-shaped rods and the second arc-shaped rods are intersected at another point in the space, and the intersection points of the. The parallel mechanism can realize the decoupling of three rotation directions and the decoupling of 3 relative rotation motions of one movement motion.
Description
Technical Field
The invention belongs to the technical field of parallel mechanisms, and particularly relates to a four-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, a parallel mechanism with 2 degrees of freedom, 3 degrees of freedom, 4 degrees of freedom and 6 degrees of freedom is common; the three-degree-of-freedom parallel mechanism is a few-degree-of-freedom parallel mechanism which is most researched and most widely applied.
The existing three-rotation parallel mechanism is characterized in that a fixed platform of the parallel mechanism is annular, and three motion branched chains which are identical in structure and are uniformly distributed in space are uniformly distributed in the circumferential direction of the fixed platform. Each motion branched chain consists of a moving pair, a rotating pair and a spherical hinge. The moving pair can move on the annular track, the rotating axes of the three rotating pairs are coplanar and intersect at one point, and the moving platform can rotate around the point in three directions. The prior art also has another three-degree-of-freedom parallel mechanism, and a movable platform and a fixed platform of the mechanism are connected by adopting 3 moving branched chains which are symmetrically distributed in the circumferential direction. Each branched chain is composed of 2 sections of arc connecting rods with the same arc center, the upper section of arc connecting rod is connected with the movable platform in a spherical hinge mode, and the upper section of arc connecting rod is installed in a cavity of the lower section of arc connecting rod and can reciprocate along the tangential direction of the arc of the cavity. All adopt revolute pair to be connected between 3 hypomere arc connecting rods and the fixed platform, the axis of revolute pair coincides each other to perpendicular to fixed platform points to the arc center of arc connecting rod. The rotation of the movable platform around the center of the arc-shaped connecting rod in 3 directions is realized by driving the lower arc-shaped connecting rod to rotate around the fixed platform. The prior art also provides a one-movement three-rotation four-freedom-degree rotation and movement complete decoupling parallel mechanism which consists of a movable platform, a fixed platform and three branched chains with double rotation freedom degrees, so that the movable platform can move in one dimension and rotate in three degrees of freedom in spherical surface around a fixed point.
However, the above parallel mechanisms all have 3 degrees of freedom, the rotation center is the intersection point of the revolute pair or the center of the arc-shaped connecting rod, but the rotation center is fixed, and the rotation center of the latter parallel mechanism is adjusted only by the bottom revolute pair, so that when the rotation center is adjusted in a large range, the movement displacement of the revolute pair is large, and the force/moment transmission performance of the movement branched chain is poor. Based on this, there is a need for a new parallel mechanism.
Disclosure of Invention
An object of the present invention is to solve the above-mentioned problems and to provide at least the advantages which will be described later.
The invention also aims to provide a four-degree-of-freedom parallel mechanism which can realize the decoupling of three rotation directions and the decoupling of one movement motion relative to 3 rotation motions.
To achieve these objects and other advantages in accordance with the purpose of the invention, there is provided a four-degree-of-freedom parallel mechanism including: the device comprises a fixed platform, a movable platform and three moving branched chains positioned between the fixed platform and the movable platform;
each motion branch chain comprises a crank rocker mechanism, a first arc-shaped rod and a second arc-shaped rod, the crank rocker mechanism comprises a connecting rod, a first motor capable of moving along the axial direction of the connecting rod is mounted on the connecting rod, the axes of three first motor output shafts are intersected at one point in a space, one end of each first arc-shaped rod is connected with a revolute pair between the movable platforms, the other end of each first arc-shaped rod is connected with a revolute pair at one end of the corresponding second arc-shaped rod, the other end of each second arc-shaped rod is connected with an output shaft of the corresponding first motor, the axis of the revolute pair between the corresponding first arc-shaped rod and the movable platform and the axis of the revolute pair between the corresponding first arc-shaped rod and the corresponding second arc-shaped rod are intersected at another point in the space, and the intersection.
Preferably, the four-degree-of-freedom parallel mechanism further comprises a crank and a rocker which are positioned on two sides of the connecting rod, two ends of the connecting rod are respectively and rotatably connected with one end of the crank and one end of the rocker, the fixed platform is further fixedly connected with a first supporting rod and a second supporting rod, the first supporting rod is rotatably connected with the other end of the rocker, the second supporting rod is provided with a second motor, and an output shaft of the second motor is connected with the crank to drive the crank to rotate.
Preferably, the four-degree-of-freedom parallel mechanism further comprises a bracket, the bracket is mounted on the connecting rod and can move along the axial direction of the connecting rod, and the first motor is mounted on the bracket.
The invention at least comprises the following beneficial effects:
1. according to the four-degree-of-freedom parallel mechanism, the crank of the crank rocker mechanism is driven to rotate, so that the intersection point of the axes of the output shafts of the three first motors moves up and down along the normal of the fixed platform, and the movable platform has reciprocating motion along the normal direction of the fixed platform. Simultaneously, the second arc-shaped rod is driven to rotate through the rotation of the first motor, so that the first arc-shaped rod is rotated, the movable platform rotates around an X shaft, a Y shaft and a Z shaft of a three-dimensional coordinate system with the intersection point of the axis of the revolute pair of the first arc-shaped rod and the axis of the revolute pair of the second arc-shaped rod as the origin of the three-dimensional coordinate system, and the parallel mechanism can realize the decoupling of three rotation directions and the decoupling of 3 relative rotation motions of one moving motion.
2. According to the four-degree-of-freedom parallel mechanism, the parallel mechanism is driven by the three second motors 9 and the three first motors to realize four-degree-of-freedom motion, so that the force/torque transmission of the motion branch chain is facilitated, the working space of the parallel mechanism can be increased, the four-degree-of-freedom parallel mechanism is simple in structure and high in flexibility, and the four-degree-of-freedom parallel mechanism can be applied to the fields of virtual axis machine tools, aviation simulation equipment, ankle joint rehabilitation equipment and the like.
Drawings
FIG. 1 is a schematic structural diagram of a four-DOF parallel mechanism according to the present invention;
FIG. 2 is a schematic view of the axes of the output shafts of three first motors of the present invention intersecting at a point;
fig. 3 is a schematic view of a point where the axis of the revolute pair between the first arc-shaped rod and the movable platform and the axis of the revolute pair between the first arc-shaped rod and the second arc-shaped rod intersect.
Detailed Description
The present invention is further described in detail below with reference to the attached drawings so that those skilled in the art can implement the invention by referring to the description text.
It should be noted that in the description of the present invention, the terms "lateral", "longitudinal", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.
As shown in fig. 1 to 3, a four-degree-of-freedom parallel mechanism includes: the cross sections of the fixed platform 1 and the movable platform 12 can be circular, and actually can be set to be square, rectangular and the like according to needs, three moving branched chains are arranged between the fixed platform 1 and the movable platform 12, and the three moving branched chains are uniformly distributed on the fixed platform 1 at intervals; wherein each motion branch chain comprises a crank rocker mechanism, a first arc rod 11 and a second arc rod 10, the crank rocker mechanism comprises a crank, a connecting rod 6 and a rocker which are hinged with each other, the connecting rod 6 is provided with a first motor 8 which can move along the axial direction of the connecting rod 6, and the axes of the output shafts of the first motors 8 on the connecting rods 6 of the three crank rocker mechanisms are intersected with one point in the space, as shown in fig. 2 at point O, two ends of the first arc rod 11 are connected with the movable platform 12 and the second arc rod 10 through revolute pairs respectively, the other end of the second arc rod 10 is connected with the output shaft of the first motor 8, the axis of the revolute pair between the first arc rod 11 and the movable platform 12 and the axis of the revolute pair between the first arc rod 11 and the second arc rod 10 intersect at another point in the space, as shown in fig. 3 at point O, and the point coincides with the intersection point of the axes of the output shafts of the three first motors 8. According to the four-degree-of-freedom parallel mechanism, the crank of the crank rocker mechanism is driven to rotate, so that an angle is formed between the connecting rod 6 and the fixed platform 1, the output axis of the first motor 8 is parallel to the connecting rod 6, the same included angle is formed between the output axis of the first motor 8 and the fixed platform 1, the intersection point of the output axes of the three first motors 8 moves up and down along the normal of the fixed platform 1, and the movable platform 12 has reciprocating motion along the normal direction of the fixed platform 1. Meanwhile, the second arc-shaped rod 10 is driven to rotate by the rotation of the first motor 8, so that the first arc-shaped rod 11 rotates, the movable platform 12 rotates around the intersection point of the axis of the revolute pair of the first arc-shaped rod 11 and the axis of the revolute pair of the second arc-shaped rod 10, namely, the point O in fig. 2 and 3, and the point X, the axis Y and the axis Z of the three-dimensional coordinate system taking the point as the origin of the three-dimensional coordinate system, namely, the rotation center of the movable platform 12 of the parallel mechanism is the point O, the movable platform 120 performs three-degree-of-freedom rotational motion around the point O, the parallel mechanism can realize decoupling in three rotational directions and decoupling of one moving motion relative to 3 rotational motions, and the transmission performance of the force/moment of the moving branch chain of.
In another technical scheme, the crank and rocker mechanism further comprises a crank 3 and a rocker 5 which are positioned at two sides of a connecting rod 6, two ends of the connecting rod 6 are respectively rotatably connected with one end of the crank 3 and one end of the rocker 5, specifically, two ends of the connecting rod 6 are respectively hinged with the crank 3 and the rocker 5, meanwhile, a first supporting rod 4 and a second supporting rod 2 are fixedly connected on a fixed platform 1, the first supporting rod 4 and the second supporting rod 2 are fixed on the fixed platform 1 in a welding mode, the lengths of the first supporting rod 4 and the second supporting rod 2 are the same, the lengths of the crank 3 and the rocker 5 are different, the first supporting rod 4 is rotatably connected with the other end of the rocker 5, a second motor 9 is mounted on the second supporting rod 2, an output shaft of the second motor 9 is connected with the crank 3 to drive the crank 3 to rotate, so that an angle is formed between the connecting rod 6 and the fixed platform 1, and further an output axis of the first motor 8, and forms the same included angle with the fixed platform 1. The parallel mechanism is driven by means of redundant motors, namely the three second motors 9 and the three first motors 8 drive the parallel mechanism to realize four-degree-of-freedom movement, so that the parallel mechanism is beneficial to force/torque transmission of the moving branch chains on the one hand, can increase the working space of the parallel mechanism, is simple in structure and high in flexibility, and can be applied to the fields of virtual axis machine tools, aviation simulation equipment, ankle joint rehabilitation equipment and the like.
In another technical scheme, the device further comprises a bracket 7, the bracket 7 is mounted on the connecting rod 6 and can move along the axial direction of the connecting rod 6, and the first motor 8 is mounted on the bracket 7. Specifically, this support 7 can be a strip cuboid, has seted up a through-hole on this cuboid, and connecting rod 6 passes this through-hole and can follow this through-hole round trip movement, and first motor 8 is installed on this support 7 and the output shaft is connected with second arc pole 10, and first motor 8 drives second arc pole 10 and rotates.
While embodiments of the invention have been described above, it is not limited to the applications set forth in the description and the embodiments, which are fully applicable in various fields of endeavor to which the invention pertains, and further modifications may readily be made by those skilled in the art, it being understood that the invention is not limited to the details shown and described herein without departing from the general concept defined by the appended claims and their equivalents.
Claims (3)
1. A four-degree-of-freedom parallel mechanism is characterized by comprising: the device comprises a fixed platform, a movable platform and three moving branched chains positioned between the fixed platform and the movable platform;
each motion branched chain comprises a crank rocker mechanism, a first arc-shaped rod and a second arc-shaped rod, the crank rocker mechanism comprises a connecting rod, a first motor capable of moving along the axial direction of the connecting rod is mounted on the connecting rod, the axes of three first motor output shafts are intersected at one point in a space, one end of the first arc-shaped rod is connected with the movable platform through a revolute pair, the other end of the first arc-shaped rod is connected with one end of the second arc-shaped rod through a revolute pair, the other end of the second arc-shaped rod is connected with the output shaft of the first motor, the axis of the revolute pair between the first arc-shaped rod and the movable platform and the axis of the revolute pair between the first arc-shaped rod and the second arc-shaped rod are intersected at another point in the space, and the point is coincided with the intersection point.
2. The four-degree-of-freedom parallel mechanism according to claim 1, wherein the crank and rocker mechanism further comprises a crank and a rocker located on both sides of the connecting rod, both ends of the connecting rod are rotatably connected with one end of the crank and one end of the rocker, respectively, the fixed platform is further fixedly connected with a first supporting rod and a second supporting rod, the first supporting rod is rotatably connected with the other end of the rocker, the second supporting rod is provided with a second motor, and an output shaft of the second motor is connected with the crank to drive the crank to rotate.
3. The four degree-of-freedom parallel mechanism of claim 1, further comprising a bracket mounted on the link and movable in the direction of the link axis, the first motor being mounted on the bracket.
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| CN201910976422.5A CN110539293B (en) | 2019-10-15 | 2019-10-15 | Four-degree-of-freedom parallel mechanism |
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| CN201910976422.5A CN110539293B (en) | 2019-10-15 | 2019-10-15 | Four-degree-of-freedom parallel mechanism |
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| CN113041517B (en) * | 2021-04-30 | 2023-10-10 | 上海联影医疗科技股份有限公司 | Motion platform, radiotherapy bed and medical equipment |
| CN114559421B (en) * | 2022-04-24 | 2022-07-29 | 西安德普赛科计量设备有限责任公司 | Completely-decoupled cylindrical coordinate 3-movement parallel mechanism |
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| CN101497198B (en) * | 2009-02-24 | 2011-01-05 | 燕山大学 | Three-freedom degree rotary motion parallel connection mechanism with remote motion centre |
| US9579786B2 (en) * | 2013-09-26 | 2017-02-28 | Wen-Der TRUI | Spherical coordinates manipulating mechanism |
| CN103909526B (en) * | 2014-04-11 | 2016-05-11 | 北京航空航天大学 | The two degrees of freedom parallel manipulator wrist that a kind of motor pattern is variable |
| CN104308835A (en) * | 2014-10-24 | 2015-01-28 | 天津大学 | Plane-symmetry three-rotating parallel connection mechanism |
| CN104985610B (en) * | 2015-07-02 | 2017-03-08 | 上海交通大学 | One mobile three rotates four-degree-of-freedom rotates mobile full decoupled parallel institution |
| CN106289696B (en) * | 2016-10-10 | 2019-03-22 | 镇江高等职业技术学校 | The three translational vibration platforms based on parallel institution |
| CN206519947U (en) * | 2017-03-13 | 2017-09-26 | 河北工业大学 | A kind of three-branch chain six-freedom degree parallel mechanism with arc prismatic pair |
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Effective date of registration: 20220420 Address after: 435002 Huangshi economic and Technological Development Zone, Hubei Province Room 301, R & D building, building B, No. 189, Jinshan Avenue, Tieshan District Patentee after: Hubei Hengcheng Intelligent Technology Co.,Ltd. Address before: 435003 No. 16 Guilin North Road, Hubei, Huangshi Patentee before: HUBEI POLYTECHNIC University |