CN108582152B - Joint mechanism with three degrees of freedom and capable of rotating at fixed point - Google Patents
Joint mechanism with three degrees of freedom and capable of rotating at fixed point Download PDFInfo
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- CN108582152B CN108582152B CN201810453291.8A CN201810453291A CN108582152B CN 108582152 B CN108582152 B CN 108582152B CN 201810453291 A CN201810453291 A CN 201810453291A CN 108582152 B CN108582152 B CN 108582152B
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- connecting rod
- revolute pair
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J17/00—Joints
- B25J17/02—Wrist joints
- B25J17/0283—Three-dimensional joints
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Abstract
The invention discloses a three-degree-of-freedom joint mechanism capable of rotating at a fixed point, which comprises a rack (1), a composite revolute pair (2), a first connecting rod (3), a first revolute pair (4), a second connecting rod (5), a second revolute pair (6), a third connecting rod (7), a sliding pair external member (8) and a fourth connecting rod (9), wherein the composite revolute pair (2) is connected with the rack (1), the composite revolute pair (2) is connected with the first connecting rod (3), the first connecting rod (3) is connected with the first revolute pair (4), the first revolute pair (4) is connected with the second connecting rod (5), the second connecting rod (5) is connected with the second revolute pair (6), the second revolute pair (6) is connected with the third connecting rod (7), and the third connecting rod (7) is connected with the sliding pair external member (8). The invention has the following advantages: the three fixed-point rotation functions are realized, the problem of motion continuity is solved, the coordinated synchronous motion among the components can be ensured, the overall structure is simpler, and meanwhile, objects can be accommodated through the mechanism, so that the three fixed-point rotation mechanism is widely applied.
Description
Technical Field
The invention relates to the field of mechanical design, in particular to a three-degree-of-freedom joint mechanism capable of rotating at fixed points.
Background
At present, the robot technology is widely applied to the fields of society, life, military, industrial production and the like. Generally, robots with different functions adopt different joint design mechanisms according to different tasks, and establish corresponding joint configuration schemes, such as shoulder joints, wrist joints, waist joints and the like. As an index for evaluating the movement performance of these joint mechanisms, the degree of freedom of joints is always an important matter in designing and developing robots.
Generally, industrial robots mostly adopt a single-degree-of-freedom rotary joint form, so that the installation and motion control of a rotary motor can be greatly facilitated. With the development of linear motor technology, some sliding joint mechanisms are gradually applied and popularized.
From the angle of freedom, the sliding joint is still a single-degree-of-freedom mechanism, and the sliding joint replaces unidirectional rotation of a fixed shaft by translational one-dimensional motion. In actual production, in order to realize multi-degree-of-freedom motion of an industrial robot, a multi-link composite mechanism is generally adopted to realize the multi-degree-of-freedom, and even redundant degrees of freedom are generated to improve motion performance. Theoretically, in various motion modes, three-degree-of-freedom fixed point rotation motion is difficult to realize, and the three-degree-of-freedom rotation mechanism has great application requirements in daily life and industrial production.
In addition, industrial robots are mostly solid link mechanisms, which mostly aim at force-type tasks such as grabbing, supporting, carrying and the like, and do not require accurate motion transmission. At the same time, they also do not have the functional requirements of accommodating objects. However, in certain engineering applications, there is a functional need to contain objects within a confined space. For example, underwater high-pressure suits transmitted by divers during deep sea exploration, and astronauts' internal-pressure type astronautics suits under the outer space environment, etc. They often have low requirements for load bearing and good motion performance, and at the same time they are required to be able to accommodate the working personnel well without causing injury to the personnel. It follows that such joints must have good kinematic properties.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the three-degree-of-freedom fixed-point rotary motion of the traditional industrial robot is difficult to realize, the multiple degrees of freedom are usually realized through a multi-connecting-rod composite mechanism, even redundant degrees of freedom are generated to improve the motion performance, the complexity of the structure is increased, and the defect that an object cannot be accommodated exists.
The technical problem proposed by the invention is solved as follows: the joint mechanism comprises a rack, a composite revolute pair, a first connecting rod, a first revolute pair, a second connecting rod, a second revolute pair, a third connecting rod, a sliding pair external member and a fourth connecting rod;
the outer ring of the composite rotating pair is connected with the rack, a global coordinate system xyz is fixed at the rack, the composite rotating pair is fixed at an origin o of the coordinate system xyz, the inner ring of the composite rotating pair is fixedly connected with one end of a first connecting rod, the other end of the first connecting rod is fixedly connected with the outer ring of the first rotating pair, the inner ring of the first rotating pair is fixedly connected with one end of a second connecting rod, the other end of the second connecting rod is fixedly connected with the inner ring of the second rotating pair, the outer ring of the second rotating pair is fixedly connected with one end of a third connecting rod, the other end of the third connecting rod is fixedly connected with the outer ring of the sliding pair suite, a fourth connecting rod and the inner ring of the sliding pair suite form a sliding pair, and one end of the fourth connecting rod is connected with the origin o in a spherical hinge pair manner;
the central axis of the compound revolute pair is parallel to the y coordinate axis of the global coordinate system, and the included angle between the first connecting rod and the central axis of the compound revolute pair is α1The first connecting rod can rotate around the fixed shaft relative to the composite rotating pair, and the relative rotation angle between the first connecting rod and the composite rotating pair is theta1The included angle between the second connecting rod and the first connecting rod is α2The second connecting rod can rotate around the fixed axis relative to the first connecting rod, and the relative rotation angle between the second connecting rod and the first connecting rod is theta2The included angle between the third connecting rod and the second connecting rod is α3The third connecting rod can rotate around a fixed axis relative to the second connecting rod, and the relative rotation angle of the third connecting rod and the second connecting rod is theta3The fourth connecting rod and the third connecting rod are parallel to each other at the sliding pair, and the sliding direction of the sliding pair is always parallel to the third connecting rod and the fourth connecting rod;
the inner ring and the outer ring of all the revolute pairs can relatively rotate, and all the connecting rods are objects playing a connecting role and are not limited to rod-shaped objects;
the length of the first connecting rod is d1The length of the second connecting rod is d2The length of the third connecting rod is d3。
d1＝r1sinα1；
d2＝r1cosα1sinα2；
d3＝r1cosα1cosα2sinα3；
Wherein r is1Is the radius of any circle with the origin o as the center.
α3＝α2-α1；
α2＞α1。
The composite revolute pair comprises an inner revolute pair and an outer revolute pair, the central axes of the two revolute pairs are kept coincident, the upper end faces of the two revolute pairs are horizontally aligned, meanwhile, the outer ring of the inner revolute pair is fixedly connected with the inner ring of the outer revolute pair to ensure that the composite revolute pair has two rotational degrees of freedom, the inner ring of the inner revolute pair forms the inner ring of the composite revolute pair, and the outer ring of the outer revolute pair forms the outer ring of the composite revolute pair.
θ1The value range of (a) is 0-360 DEG, theta2And theta3The value ranges of the two are the same and are all 0-90 degrees.
All revolute pairs adopt ball bearings, and sliding pair external members adopt sliding bearings.
The invention has the following advantages: the structure realizes the function of three fixed-point rotation, solves the problem of motion continuity, can ensure the coordinated synchronous motion among components, makes the whole structure simpler, and can also accommodate objects through the mechanism, thereby realizing more extensive application.
Drawings
FIG. 1 is a schematic structural diagram of a three-degree-of-freedom joint mechanism capable of fixed point rotation;
fig. 2 is a specific embodiment of a joint mechanism that uses three degrees of freedom and can rotate at fixed points (for convenience of displaying the internal structure of a component, a sliding pair kit is hidden);
fig. 3 is a perspective view of a specific embodiment of a joint mechanism with three degrees of freedom and fixed point rotation (for convenience of displaying the internal structure of the component, the sliding pair kit is not shown);
the device comprises a rack 1, a composite revolute pair 2, a first connecting rod 3, a first revolute pair 4, a second connecting rod 5, a second revolute pair 6, a third connecting rod 7, a sliding pair kit 8 and a fourth connecting rod 9.
Detailed Description
The invention will be further described with reference to the accompanying drawings.
As shown in fig. 2 and 3, the numbers corresponding to those of fig. 1 are used for convenience of explanation. The joint mechanism scheme comprises a rack 1, a composite revolute pair 2, a first connecting rod 3, a first revolute pair 4, a second connecting rod 5, a second revolute pair 6, a third connecting rod 7, a sliding pair external member 8 and a fourth connecting rod 9, wherein the rack 1 is fixedly connected to an outer ring of the composite revolute pair 2, and one end of the first connecting rod 3 is connected to an inner ring of the composite revolute pair 2.
The composite revolute pair 2 comprises an inner ball bearing and an outer ball bearing, and can also be connected by other bearings such as a ball bearing, a needle bearing and the like. The central axes of the two ball bearings are kept coincident, the upper end faces are horizontally aligned, and meanwhile, the outer ring of the inner ball bearing is fixedly connected with the inner ring of the outer ball bearing, so that the composite revolute pair 2 is guaranteed to have two rotational degrees of freedom integrally, and can rotate around the central axis of the inner ball bearing and also rotate around the central axis of the outer ball bearing. The inner ring of the inner ball bearing forms the inner ring of the composite revolute pair 2, and the outer ring of the outer revolute pair forms the outer ring of the composite revolute pair 2.
The other end of the first link 3 is fixedly connected to the outer ring of the first revolute pair 4, and the first revolute pair 4 is preferably a ball bearing, but other bearing connections such as a ball bearing, a needle bearing and the like can also be adopted. The inner ring of the first revolute pair 4 is fixedly connected with one end of a second connecting rod 5, the other end of the second connecting rod 5 is fixedly connected with the inner ring of a second revolute pair 6, the second revolute pair 6 is preferably a ball bearing, and other bearing connections such as a ball bearing, a needle bearing and the like can also be adopted. The outer ring of the second revolute pair 6 is fixedly connected with one end of a third connecting rod 7, the other end of the third connecting rod 7 is fixedly connected with the outer ring of a sliding pair external member 8, the sliding pair external member 8 is preferably a sliding bearing, and in order to display the internal structure of a component conveniently, the sliding pair external member 8 is hidden in the figures 2 and 3, the inner ring of the sliding pair external member 8 is sleeved on a fourth connecting rod 9 and can freely slide on the fourth connecting rod 9, the fourth connecting rod 9 is connected with the central point of the rack 1 through a spherical hinge pair, and the fourth connecting rod 9 can rotate around the central point of the rack 1 in a universal mode.
The first connecting rod 3, the second connecting rod 5 and the third connecting rod 7 are all rigid shells, and the fourth connecting rod 9 is a rod body.
As shown in fig. 2, in order to facilitate explanation of the structure of the present embodiment, the connecting lines of the midpoints between the upper and lower sides of the section of the symmetry plane of the first link 3, the second link 5, and the third link 7 represent the direction and length of each link, respectively.
The central axis of the composite rotary pair 2 is in the vertical direction, and the central axis of the composite rotary pair 2 is between the first connecting rod 3 and the central axisIncluded angle is α1Since the first link 3 is fixed on the inner ring of the compound revolute pair 2, the first link 3 can perform fixed-axis rotation relative to the compound revolute pair 2, and the relative rotation angle θ between the first link 3 and the compound revolute pair 21The range is 0 degree to 360 degrees, namely the first connecting rod 3 can freely rotate in a fixed axis way.
The included angle between the second connecting rod 5 and the first connecting rod 3 is α2And the second link 5 can perform fixed-axis rotation relative to the first link 3, and the relative rotation angle theta between the second link 5 and the first link 32Is 0 to 90 degrees.
The included angle between the third connecting rod 7 and the second connecting rod 5 is α3And the third connecting rod 7 can perform fixed-axis rotation relative to the second connecting rod 5, and the third connecting rod 7 and the second connecting rod 5 rotate relatively by an angle theta3Is a relative rotation angle theta with the second link 5 and the first link 32The same applies to a range of 0 to 90 degrees.
The fourth link 9 and the third link 7 are parallel to each other, and the sliding direction of the sliding pair kit 8 is always parallel to the third link 7 and the fourth link 9.
The first link 3 has a length d1The length of the second link 5 is d2The length of the third link 7 is d3The relationship between the length of each connecting rod and the included angle between the connecting rods is as follows:
d1＝r1sinα1；
d2＝r1cosα1sinα2；
d3＝r1cosα1cosα2sinα3；
wherein r is1Is the outer ring radius of the composite revolute pair 2.
Meanwhile, the included angle between the connecting rods also satisfies the following relational expression:
α3＝α2-α1；
α2＞α1。
in actual operation, the fourth connecting rod 9 is rotated around the center point of the frame 1 in a universal manner to drive the sliding pair member 8 on the fourth connecting rod 9 to slide, and since the outer ring of the sliding pair member 8 is fixedly connected with one end of the third connecting rod 7, the third connecting rod 7 can follow the sliding pair member 8 to slide along the fourth connecting rod 9.
The other end of the third link 7 is connected with the outer ring of the second revolute pair 6, so that the second link 5, one end of which is fixed on the inner ring of the second revolute pair 6, can rotate around the axis of the second revolute pair 6.
The other end of the second connecting rod 5 is fixed on the inner ring of the first revolute pair 4, so that the inner ring of the first revolute pair 4 and the inner ring of the second revolute pair 6 synchronously rotate through the second connecting rod 5.
Since the outer ring of the first revolute pair 4 rotates relative to the inner ring, the first link 3, which is fixed at one end to the outer ring of the first revolute pair 4, also rotates. Because the composite revolute pair 2 has two degrees of freedom and the other end of the first link 3 is fixed on the inner ring of the composite revolute pair 2, the composite revolute pair 2 can satisfy all rotation angles of the first link 3 to ensure that the fourth link 9 can rotate freely.
Therefore, by changing the position of the fourth connecting rod 9, the joint mechanism can realize three-degree-of-freedom fixed-point rotation to adapt to actual production requirements, so that the problem that the movement in the production cannot be continuously carried out is solved. Simultaneously, the size of the inner ring of each revolute pair can be adjusted to accommodate objects, so that the requirement of using the structure in the joint mechanism is met, the problem that knees or elbows of aerospace suits, underwater high-pressure suits and the like are difficult to bend is solved, and the joint part can move more flexibly through a simpler structure.
The invention is described above in further detail by means of the embodiments shown in the drawings, which are given by way of illustration of the invention described above, but it should not be understood that the scope of the subject matter described above is limited to the examples described.
Claims (6)
1. A three-degree-of-freedom joint mechanism capable of rotating at fixed points is characterized by comprising a rack (1), a composite revolute pair (2), a first connecting rod (3), a first revolute pair (4), a second connecting rod (5), a second revolute pair (6), a third connecting rod (7), a sliding pair external member (8) and a fourth connecting rod (9);
the outer ring of the composite revolute pair (2) is connected with the rack (1), a global coordinate system xyz is fixed at the rack (1), the composite revolute pair (2) is fixed at an origin o of the coordinate system xyz, the inner ring of the composite revolute pair (2) is fixedly connected with one end of a first connecting rod (3), the other end of the first connecting rod (3) is fixedly connected with the outer ring of a first revolute pair (4), the inner ring of the first revolute pair (4) is fixedly connected with one end of a second connecting rod (5), the other end of the second connecting rod (5) is fixedly connected with the inner ring of a second revolute pair (6), the outer ring of the second revolute pair (6) is fixedly connected with one end of a third connecting rod (7), the other end of the third connecting rod (7) is fixedly connected with the outer ring of a sliding pair external member (8), a fourth connecting rod (9) and the inner ring of the sliding pair external member (8) form a sliding pair, and one end of the fourth connecting rod (9) is connected with the origin o in a spherical hinge joint;
the central axis of the composite revolute pair (2) is parallel to the y coordinate axis of the global coordinate system, and the included angle between the first connecting rod (3) and the central axis of the composite revolute pair (2) is α1The first connecting rod (3) can rotate in a fixed axis manner relative to the composite revolute pair (2), and the relative rotation angle between the first connecting rod (3) and the composite revolute pair (2) is theta1The included angle between the second connecting rod (5) and the first connecting rod (3) is α2The second connecting rod (5) can rotate around a fixed axis relative to the first connecting rod (3), and the relative rotation angle between the second connecting rod (5) and the first connecting rod (3) is theta2The included angle between the third connecting rod (7) and the second connecting rod (5) is α3The third connecting rod (7) can perform fixed-axis rotation relative to the second connecting rod (5), and the relative rotation angle of the third connecting rod (7) and the second connecting rod (5) is theta3The fourth connecting rod (9) and the third connecting rod (7) are parallel to each other at the sliding pair, and the sliding direction of the sliding pair is always parallel to the third connecting rod (7) and the fourth connecting rod (9);
the inner ring and the outer ring of all the revolute pairs can relatively rotate, and all the connecting rods are objects playing a connecting role and are not limited to rod-shaped objects;
the length of the first connecting rod (3) is d1The length of the second connecting rod (5) is d2The length of the third connecting rod (7) is d3；
The fourth connecting rod (9) is rotated around the center point of the rack (1) in a universal manner to drive the sliding auxiliary sleeve (8) on the fourth connecting rod (9) to slide, and the outer ring of the sliding auxiliary sleeve (8) is fixedly connected with one end of the third connecting rod (7), so that the third connecting rod (7) can slide along with the sliding auxiliary sleeve (8) along the fourth connecting rod (9);
the outer ring of the first rotating pair (4) can rotate relative to the inner ring, so that the first connecting rod (3) with one end fixed on the outer ring of the first rotating pair (4) can also rotate, and the composite rotating pair (2) has two degrees of freedom, and the other end of the first connecting rod (3) is fixed on the inner ring of the composite rotating pair (2), so that the composite rotating pair (2) can meet all rotation angles of the first connecting rod (3) to ensure that the fourth connecting rod (9) can rotate freely; by changing the position of the fourth connecting rod (9), the joint mechanism can realize three-degree-of-freedom fixed-point rotation.
2. The three-degree-of-freedom joint mechanism capable of fixed point rotation according to claim 1,
d1＝r1sinα1；
d2＝r1cosα1sinα2；
d3＝r1cosα1cosα2sinα3；
wherein r is1Is the radius of any circle with the origin o as the center.
3. The three-degree-of-freedom joint mechanism capable of fixed point rotation according to claim 1,
α3＝α2-α1；
α2＞α1。
4. the joint mechanism with three degrees of freedom and fixed point rotation according to claim 1 is characterized in that the composite revolute pair (2) comprises an inner revolute pair and an outer revolute pair, the central axes of the two revolute pairs are kept coincident, the upper end surfaces of the two revolute pairs are horizontally aligned, and meanwhile, the outer ring of the inner revolute pair is fixedly connected with the inner ring of the outer revolute pair to ensure that the composite revolute pair (2) has two rotational degrees of freedom, the inner ring of the inner revolute pair forms the inner ring of the composite revolute pair (2), and the outer ring of the outer revolute pair forms the outer ring of the composite revolute pair (2).
5. The three-degree-of-freedom joint mechanism capable of fixed point rotation according to claim 1, wherein θ is1The value range of (a) is 0-360 DEG, theta2And theta3The value ranges of the two are the same and are all 0-90 degrees.
6. The three-degree-of-freedom joint mechanism capable of fixed point rotation according to claim 1, wherein all revolute pairs adopt ball bearings, and the sliding pair kit (8) adopts sliding bearings.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810453291.8A CN108582152B (en) | 2018-05-14 | 2018-05-14 | Joint mechanism with three degrees of freedom and capable of rotating at fixed point |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810453291.8A CN108582152B (en) | 2018-05-14 | 2018-05-14 | Joint mechanism with three degrees of freedom and capable of rotating at fixed point |
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| Publication Number | Publication Date |
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| CN108582152A CN108582152A (en) | 2018-09-28 |
| CN108582152B true CN108582152B (en) | 2020-09-29 |
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| CN201810453291.8A Expired - Fee Related CN108582152B (en) | 2018-05-14 | 2018-05-14 | Joint mechanism with three degrees of freedom and capable of rotating at fixed point |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110877337B (en) * | 2019-11-29 | 2020-11-24 | 武汉科技大学 | Intelligent control method, chip and system for three-link manipulator |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3405406A (en) * | 1966-07-19 | 1968-10-15 | Nasa Usa | Hard space suit |
| US4598427A (en) * | 1984-12-20 | 1986-07-08 | The United States Of America As Represented By The Administrator, National Aeronautics And Space Administration | Elbow and knee joint for hard space suits |
| US4594734A (en) * | 1984-12-20 | 1986-06-17 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Shoulder and hip joint for hard space suits |
| CN107082124B (en) * | 2017-06-14 | 2021-04-06 | 电子科技大学 | Aerospace suit hip joint |
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