CN107097217B - Spherical parallel mechanism with reconstruction capability of movable platform - Google Patents
Spherical parallel mechanism with reconstruction capability of movable platform Download PDFInfo
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- CN107097217B CN107097217B CN201710476069.5A CN201710476069A CN107097217B CN 107097217 B CN107097217 B CN 107097217B CN 201710476069 A CN201710476069 A CN 201710476069A CN 107097217 B CN107097217 B CN 107097217B
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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
- B25J9/0045—Programme-controlled manipulators having parallel kinematics with kinematics chains having a rotary joint at the base
- B25J9/0048—Programme-controlled manipulators having parallel kinematics with kinematics chains having a rotary joint at the base with kinematics chains of the type rotary-rotary-rotary
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Abstract
The utility model provides a move sphere parallel mechanism that platform has reconsitution ability, includes the frame, moves platform and motion branch chain, it comprises the sphere multibar mechanism of four piece at least connecting rods to move the platform, each connecting rod rotates the connection through connecting rod revolute pair head and the tail and encloses and close and form and move the platform, motion branch chain one end is passed through the frame revolute pair and is connected with the frame rotation, the other end is connected with moving the platform rotation through moving the platform revolute pair, wherein move platform revolute pair and connecting rod revolute pair coaxial line, the quantity of motion branch chain is the same with the quantity of the connecting rod that moves the platform and contain, the connecting rod revolute pair, the axis of frame revolute pair and moving the platform revolute pair crosses in the same point. The invention improves the rotation capacity of the movable platform, increases the actual available working space, and simultaneously improves the rigidity of the mechanism, thereby improving the load capacity and the movement precision of the mechanism and improving the working performance of the mechanism.
Description
Technical Field
The invention relates to a parallel mechanism, in particular to a spherical parallel mechanism with a movable platform having reconstruction capability.
Background
The parallel mechanism is a closed loop mechanism which is formed by connecting a movable platform and a static platform through at least two independent motion chains, has two or more degrees of freedom and is driven in a parallel mode. Compared with a serial robot, the parallel robot has the following advantages: the accumulated error is small, and the precision is high; the driving device can be arranged on the fixed platform or close to the fixed platform, and the moving part has light weight, high speed and good dynamic response; compact structure, high rigidity and large bearing capacity. Therefore, the parallel robot has the same rigidity to the equipment,
The application is wider in occasions with higher requirements on movement speed, positioning accuracy or load.
A less-dof parallel mechanism refers to a parallel mechanism with less than 6 degrees of freedom, and may be applied to many work tasks that are suitable for operation of a parallel mechanism, but do not require all 6 degrees of freedom. Compared with a parallel mechanism with 6 degrees of freedom, the parallel mechanism with less degrees of freedom has the advantages of simple structure, easy control, convenient manufacture, low price and the like. The spherical parallel mechanism is one of important few-degree-of-freedom parallel mechanisms, and has been applied to the actual engineering fields of satellite tracking follow-up devices, numerical control rotary tables, electronic smart eyes and the like.
However, due to the limitation of singular configurations, the rotating capability of the movable platform of the parallel mechanism is often smaller, and even a relatively simple planar parallel mechanism can achieve a rotating range which does not exceed 180 degrees in theory and is smaller in practice; the singular configuration also affects the flexibility of the motion of the movable platform, because the load transfer efficiency of the movable platform is rapidly reduced when the movable platform is close to the singular configuration; in addition, the bearing capacity is poor when the number of the moving branched chains of the mechanism is small, so that the working performance of the moving platform is affected.
The redundant driving parallel mechanism is a parallel mechanism with the number of input members more than the number of freedom degrees of output members, some parallel mechanisms can assist a platform to cross over a singular configuration by adding a redundant driving branched chain so as to obtain larger rotation capacity, but the redundant driving can cause over-constraint to generate internal force, so that the mechanism faces a complex control problem; and a part of parallel mechanisms are selected to increase redundant driving in certain branched chains, but the redundant driving results in the occurrence of a mixed structure, so that the load transmission characteristics of the original parallel mechanisms are changed.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a spherical parallel mechanism with a reconfigurable capability of a movable platform, which improves the rotation capability of the movable platform, increases the actually available working space and improves the rigidity of the mechanism, thereby improving the load capacity and the movement precision of the mechanism and improving the working performance of the mechanism.
In order to solve the technical problems, the invention adopts the following technical scheme:
the utility model provides a move sphere parallel mechanism that platform has reconsitution ability, includes the frame, moves platform and motion branch chain, it comprises the sphere multibar mechanism of four piece at least connecting rods to move the platform, each connecting rod rotates the connection through connecting rod revolute pair head and the tail and encloses and close and form and move the platform, motion branch chain one end is passed through the frame revolute pair and is connected with the frame rotation, the other end is connected with moving the platform rotation through moving the platform revolute pair, wherein move the coincidence of platform revolute pair and connecting rod revolute pair, the quantity of motion branch chain is the same with the quantity of the connecting rod that moves the platform and contain, the connecting rod revolute pair, the axis of frame revolute pair and move the platform revolute pair crosses in the same point.
The motion branched chain is composed of a driving connecting rod and a driven connecting rod, one end of the driving connecting rod is rotatably connected with the base through a base rotating pair, the other end of the driving connecting rod is rotatably connected with one end of the driven connecting rod through a connecting rod rotating pair, the other end of the driven connecting rod is rotatably connected with a movable platform rotating pair on the movable platform, and the axes of the connecting rod rotating pair, the base rotating pair and the movable platform rotating pair are intersected at the same point.
The driving connecting rod and the driven connecting rod are both arc-shaped rods.
The length of the driving connecting rod is greater than, equal to or less than that of the driven connecting rod.
The spherical multi-rod mechanism is composed of four connecting rods, the number of the moving branched chains is four, and the four moving branched chains are uniformly or irregularly distributed on the base.
The spherical multi-rod mechanism is composed of five connecting rods, the number of the moving branch chains is five, and the five moving branch chains are uniformly or irregularly distributed on the base.
The invention can assist the moving platform to cross the singular configuration by adding the moving branch chain, thereby obtaining larger rotating capability, increasing the actually available working space, and simultaneously improving the rigidity of the mechanism, thereby improving the load capacity and the moving precision of the mechanism and improving the working performance of the mechanism.
In addition, the movable platform can reconstruct the movable platform by utilizing the redundant degree of freedom of the original system, and the reconstruction capability of the movable platform can be used as the drive of the end effector arranged on the movable platform. The movable platform is additionally provided with the end effector which can convert the reconstruction capability of the movable platform into the movement along the normal direction of the spherical surface, so that an additional motor is prevented from being installed on the movable platform. Or the reconstruction capability is utilized to directly use the movable platform as an end effector to realize operations such as grabbing and the like.
Drawings
FIG. 1 is a schematic top view of the present invention;
FIG. 2 is a schematic perspective view of the present invention;
FIG. 3 is a schematic diagram of the motion of the present invention;
FIG. 4 is a schematic diagram of a mobile platform reconfiguration according to the present invention;
FIG. 5 is a schematic representation of the present invention moving and effecting reconstruction of a platform;
FIG. 6 is a schematic top view of a five-DOF spherical parallel mechanism according to the present invention;
FIG. 7 is a schematic diagram of the movement of the movable platform along the normal direction of the spherical surface after the end effector is installed;
FIG. 8 is a schematic view of a portion of the process for driving the end effector to move in the normal direction of the sphere in accordance with the present invention;
FIG. 9 is a schematic view of the process of the present invention in which the movable platform is directly used as an end effector to clamp a workpiece;
FIG. 10 is a schematic view of the present invention showing a process in which a movable platen is directly used as an end effector to clamp a workpiece;
FIG. 11 is a schematic view of the process of clamping a workpiece with the movable platform directly as an end effector according to the present invention;
FIG. 12 is a schematic view of the present invention with a movable platen directly used as an end effector for clamping a workpiece.
Detailed Description
To facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.
As shown in attached figures 1 and 2, the invention discloses a spherical parallel mechanism with a reconfigurable capability of a movable platform, which comprises a base 1, the movable platform 2 and a movable branched chain 3, wherein the movable platform 2 is composed of a spherical multi-rod mechanism comprising at least four connecting rods, each connecting rod is in head-tail rotating connection and enclosure through a connecting rod rotating pair to form the movable platform 2, one end of the movable branched chain 3 is in rotating connection with the base 1 through a base rotating pair 4, the other end of the movable branched chain is in rotating connection with the movable platform 2 through a movable platform rotating pair 21, the movable platform rotating pair and the connecting rod rotating pair are superposed, the number of the movable branched chain is the same as that of the connecting rods contained in the movable platform, and the axes of the connecting rod rotating pair, the base rotating pair and the movable platform rotating pair are converged at the same point. The number of the moving branched chains is the same as the total degree of freedom of the whole spherical parallel mechanism. The motion branched chain 3 is composed of a driving connecting rod 31 and a driven connecting rod 33, one end of the driving connecting rod 31 is rotatably connected with the machine base 1 through a machine base rotating pair 4, the other end of the driving connecting rod is rotatably connected with one end of the driven connecting rod 33 through a connecting rod rotating pair 32, the other end of the driven connecting rod 33 is rotatably connected with a movable platform rotating pair 21 on the movable platform 2, the axes of the connecting rod rotating pair 32, the machine base rotating pair 4, the connecting rod rotating pair and the movable platform rotating pair 21 are intersected at the same point, namely, the axes of the connecting rod rotating pair, the machine base rotating pair and the movable platform rotating pair are intersected and converged at the sphere center of the spherical surface parallel mechanism, and the motion of the movable platform is ensured to be completed on a spherical surface.
In addition, the driving connecting rod and the driven connecting rod are arc-shaped rods. The length of initiative connecting rod is greater than, equals or is less than the length of driven connecting rod, specifically can carry out nimble selection setting by actual conditions.
In addition, the parameters of the rod of each moving branched chain and the latitude of the arrangement of the motor for driving the moving branched chain, whether the motor is uniformly distributed or not are not particularly limited, and the parameters can be adjusted according to the required moving space and load requirements so as to achieve different moving effects. That is, when there are a plurality of moving branches, all the moving branches may be uniformly distributed on the base or irregularly distributed on the base.
The spherical parallel mechanism with specific degrees of freedom is explained in detail below.
In the first embodiment, as shown in fig. 1 and 2, the spherical multi-bar mechanism is a spherical four-bar mechanism, the spherical four-bar mechanism is composed of four connecting bars, the four connecting bars are respectively connected and enclosed by four connecting bar revolute pairs in an end-to-end rotation manner to form a movable platform, and two adjacent connecting bars can rotate by taking the connecting bar revolute pair as a rotation center. At the moment, the number of the moving branched chains is four, and the total degree of freedom of the spherical parallel mechanism is four degrees of freedom. The three-freedom-degree spherical moving platform comprises a base which drives a moving platform to move, and the moving platform can realize the movement of three degrees of freedom by power transmitted by four groups of moving branched chains, wherein the three degrees of freedom comprise two translational degrees of freedom along a spherical surface and one rotational degree of freedom around an axis in the radius direction, and the three-freedom-degree spherical moving platform is shown in an attached figure 3.
As shown in the attached figure 4, the movable platform can reconstruct the movable platform by utilizing the redundant degree of freedom of the original system, each connecting rod of the movable platform formed by the spherical four-bar mechanism rotates to a certain degree, and the reconstruction effect figure of the movable platform can be seen in the attached figure 4. Fig. 5 is a schematic diagram of the situation that when the movable platform moves normally, the position, the corner and the movable platform change simultaneously, and the action of the four moving branch chains transmits force to the movable platform, so that the position of the movable platform and the corners of two adjacent connecting rods are changed.
As shown in fig. 7 and 8, an end effector is mounted on the movable platform, and the end effector can be mounted on the movable platform revolute pair through a threaded connection. The end effector A and a connecting rod B of the movable platform are matched through threads to form a screw pair, and the screw pair and a connecting rod C of the movable platform form a moving pair; when the movable platform is reconstructed, the movable platform is driven to act by the movable branched chain, the connecting rod B rotates relative to the connecting rod C and transmits the motion to the end effector A through threaded engagement, and the rotation of the end effector A is limited by a sliding pair between the end effector A and the connecting rod C, so that the end effector A can only translate along the common axis of the end effector A, the connecting rod B and the connecting rod C, namely the direction of a spherical normal. Through the process, the reconstruction motion of the movable platform is converted into the translation of the end effector A along the normal direction of the spherical surface, so that the motor can be prevented from being installed on the movable platform, and the inertia of moving parts of the mechanism is reduced. The reconstruction capability can be used for directly using the movable platform as an end effector to realize operations such as grabbing and the like. As shown in fig. 9-12, the movable platform is directly used as an end effector, the movable platform is used for clamping a workpiece, and the movable platform is driven by four groups of moving branched chains to clamp the workpiece.
In the second embodiment, as shown in fig. 6, the spherical multi-rod mechanism is a spherical five-rod mechanism, the spherical five-rod mechanism is composed of five connecting rods, the five connecting rods are respectively connected and enclosed by five connecting rod revolute pairs in an end-to-end revolute manner to form a movable platform, the number of the five kinematic branched chains is five, and the five kinematic branched chains are uniformly distributed on the base.
The above description has been made by using a movable platform composed of a spherical four-bar mechanism and a movable platform composed of a spherical five-bar mechanism, but the above examples are not intended to be limiting. The device can also be a movable platform formed by a spherical six-rod mechanism, a movable platform formed by a spherical seven-rod mechanism and the like.
It should be noted that the above description is not intended to limit the technical solutions of the present invention, and any obvious alternative is within the protection scope of the present invention without departing from the inventive concept of the present invention.
Claims (6)
1. The utility model provides a move sphere parallel mechanism that platform has reconsitution ability, includes the frame, moves platform and motion branch chain, a serial communication port, it comprises the sphere multibar mechanism of four piece at least connecting rods to move the platform, each connecting rod rotates the connection through connecting rod revolute pair head and the tail and encloses and close and form and move the platform, motion branch chain one end is passed through the frame revolute pair and is connected with the frame rotation, the other end is rotated through moving the platform revolute pair and being connected with moving the platform, wherein move platform revolute pair and connecting rod revolute pair coaxial line, the quantity of motion branch chain is the same with the quantity of the connecting rod that moves the platform and contain, the connecting rod revolute pair, the axis of frame revolute pair and move the platform revolute pair intersects in the same point.
2. The spherical parallel mechanism with reconstruction capability of the movable platform according to claim 1, wherein the moving branch chain is composed of a driving connecting rod and a driven connecting rod, one end of the driving connecting rod is rotatably connected with the base through a base rotating pair, the other end of the driving connecting rod is rotatably connected with one end of the driven connecting rod through a connecting rod rotating pair, the other end of the driven connecting rod is rotatably connected with a movable platform rotating pair on the movable platform, and the axes of the connecting rod rotating pair, the base rotating pair, the connecting rod rotating pair and the movable platform rotating pair are intersected at the same point.
3. The spherical parallel mechanism with reconstruction capability of moving platform according to claim 2, wherein said driving connecting rod and driven connecting rod are both arc-shaped rods.
4. The spherical parallel mechanism with reconstruction capability of the moving platform according to claim 3, wherein the length of the driving link is greater than, equal to or less than that of the driven link.
5. The spherical parallel mechanism with the reconfigurable capability of the movable platform according to any one of claims 2 to 4, wherein the spherical multi-rod mechanism is composed of four connecting rods, the number of the moving branched chains is four, and the four moving branched chains are uniformly or irregularly distributed on the base.
6. The spherical parallel mechanism with the reconfigurable capability of the movable platform according to any one of claims 2 to 4, wherein the spherical multi-rod mechanism is composed of five connecting rods, the number of the movable branched chains is five, and the five movable branched chains are uniformly or irregularly distributed on the base.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201710476069.5A CN107097217B (en) | 2017-06-21 | 2017-06-21 | Spherical parallel mechanism with reconstruction capability of movable platform |
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| CN201710476069.5A CN107097217B (en) | 2017-06-21 | 2017-06-21 | Spherical parallel mechanism with reconstruction capability of movable platform |
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| CN107097217A CN107097217A (en) | 2017-08-29 |
| CN107097217B true CN107097217B (en) | 2023-03-10 |
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| CN110434840B (en) * | 2019-09-16 | 2024-04-02 | 河北工业大学 | Three-degree-of-freedom generalized spherical parallel mechanism |
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| CN101214647A (en) * | 2007-12-26 | 2008-07-09 | 燕山大学 | Spherical surface two-freedom symmetrical parallel connection robot mechanism with redundancy drive |
| CN102275161A (en) * | 2011-07-08 | 2011-12-14 | 常州大学 | Three-rotation spherical motion mechanism |
| CN202292761U (en) * | 2011-10-14 | 2012-07-04 | 北华航天工业学院 | Symmetrical parallel robot mechanism with three degrees of freedom of redundant driven plane |
| US9579786B2 (en) * | 2013-09-26 | 2017-02-28 | Wen-Der TRUI | Spherical coordinates manipulating mechanism |
| CN105459092B (en) * | 2016-01-08 | 2017-04-12 | 天津大学 | Multi-closed-loop two-degree-of-freedom rotation catching and releasing mechanism |
| CN206899231U (en) * | 2017-06-21 | 2018-01-19 | 东莞爱创机器人科技有限公司 | A kind of moving platform has the sphere parallel mechanism of re-configurability |
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