CN109849047B - Mechanical arm joint with controllable rigidity - Google Patents
Mechanical arm joint with controllable rigidity Download PDFInfo
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- CN109849047B CN109849047B CN201910239794.XA CN201910239794A CN109849047B CN 109849047 B CN109849047 B CN 109849047B CN 201910239794 A CN201910239794 A CN 201910239794A CN 109849047 B CN109849047 B CN 109849047B
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Abstract
The invention provides a mechanical arm joint with controllable rigidity. The first moving branched chain comprises six revolute pairs, and a sixth revolute pair and a seventh revolute pair are connected with the upper platform; the first rotating pair is connected with the second rotating pair through a connecting rod, the second rotating pair is connected with the third rotating pair through a connecting rod, the third rotating pair is connected with the fourth rotating pair through a connecting rod, the fourth rotating pair is connected with the fifth rotating pair through a connecting rod, and the fifth rotating pair is connected with the sixth rotating pair through a connecting rod; the second moving branched chain comprises a seventh revolute pair; the seventh revolute pair connects the upper platform and the lower platform. And the second rotating pair is driven to change the position of the axis of the third rotating pair, the position of the intersection point of the axis of the first rotating pair, the axis of the third rotating pair and the axis of the sixth rotating pair in the first chain movement is changed, the rotating condition is damaged, and the controllable rigidity and the locking at any position of the mechanism are realized.
Description
Technical Field
The invention relates to the field of robots, in particular to a mechanical arm joint with controllable rigidity.
Background
The mechanical arm is bionic electromechanical equipment and can simulate the actions of a human hand and realize operation by changing the pose of a target object. The method is widely applied to the fields of large-scale equipment, robots, sensors and micro-operation. The robot maintains a specified position and posture in space, and joints of the robot must be locked in a given posture, so that the joint locking of the robot becomes an indispensable part for the mechanism design of the robot. However, most mechanical arm joints implement the movement of the mechanism through a rotating shaft, and when the mechanical arm joints stop working, a small amount of relative rotation between two components may still be caused due to inertia and the like, so that the mechanical joint capable of implementing self-locking is designed, and the problem of improving the movement precision is a challenging problem.
The literature, "experimental research on joint locking structure of medical robot based on external friction" proposes a locking structure of mechanical arm joint based on external friction, but the friction coefficient is smaller and smaller due to long-term friction between the friction plate and the joint, and the locking capability is reduced. Chinese patent CN109421040A discloses a six-degree-of-freedom intelligent cooperative robot, which comprises a base, a plurality of nodes and a plurality of connecting rods, the base is fixedly connected with the nodes, the nodes are fixedly connected with each other or connected through the connecting rod, the motor, the brake, the encoder and the speed reducer are sequentially sleeved on the transmission shaft, a mounting groove for embedding the driver is formed in the surface of one side of the encoder mounting shell, the encoder mounting shell is provided with an outer connecting part at one side opposite to the mounting groove, the outer connecting part is used for being connected with an external structure, the center of the motor mounting shell is provided with a motor cavity, one end of the motor cavity close to the brake mounting cover is provided with an inner flange, the support sleeve is sleeved on the transmission shaft and consists of an outer ring part, a ball part and an inner ring part, the inner ring portion is tightly connected with the outer side surface of the transmission shaft, and the outer ring portion is in contact connection with the inner side surface of the encoder mounting shell. The patent still does not address the problem of motion accuracy.
Disclosure of Invention
The invention aims to provide a mechanical arm joint with controllable rigidity, and overcomes the defects of complex structure, inconvenient control and low motion precision in the prior art.
The purpose of the invention can be realized by the following technical scheme:
a mechanical arm joint with controllable rigidity comprises an upper platform, a lower platform, a first moving branch chain and a second moving branch chain, wherein the first moving branch chain and the second moving branch chain are connected between the upper platform and the lower platform,
the first moving branched chain comprises a first rotating pair, a second rotating pair, a third rotating pair, a fourth rotating pair,
A fifth revolute pair and a sixth revolute pair,
the second moving branched chain comprises a seventh revolute pair,
the sixth revolute pair is connected with the upper platform, the first revolute pair is connected with the lower platform, the seventh revolute pair is respectively connected with the upper platform and the lower platform,
the fifth rotating pair is respectively connected with the fourth rotating pair and the sixth rotating pair through two connecting rods,
the third rotating pair is respectively connected with the fourth rotating pair and the second rotating pair through a connecting rod,
the second rotating pair is connected with the first rotating pair through a connecting rod.
The axes of the first rotating pair, the third rotating pair and the sixth rotating pair are intersected at a point which is positioned on the extension line of the axis of the seventh rotating pair. And the axes of the second revolute pair, the fourth revolute pair and the fifth revolute pair are parallel to the axis space of the seventh revolute pair. The mechanism can rotate only when the axes of the two revolute pairs are coaxial, and cannot rotate when the axes of the two revolute pairs are not coaxial.
And the axis of the third revolute pair is not in the same plane with the axes of the other revolute pairs. Specifically, the axes of the first rotating pair, the third rotating pair and the sixth rotating pair are not on the same plane, and the spaces meet at a point; the axial spaces of the second revolute pair, the fourth revolute pair and the fifth revolute pair are parallel. The mechanism can rotate only when the axes of the two revolute pairs are coaxial, and cannot rotate when the axes of the two revolute pairs are not coaxial. The axes of the first rotating pair, the third rotating pair and the sixth rotating pair are intersected at a point and are equivalent to a spherical hinge, and the axis of the spherical hinge is coaxial with the axis of the seventh rotating pair on the right side in an initial state, so that the rotating condition is met. When the whole mechanism rotates to a certain angle, the axis of the third revolute pair is driven by the driving force added to the second revolute pair, so that the axis of the third revolute pair is changed, the axes of the first revolute pair, the third revolute pair and the sixth revolute pair are not converged, the coaxial condition is not met, the rigidity of the mechanism is increased at the moment, the controllability of the rigidity is realized, and the mechanism is locked. The second joint controls the rotation angle of the second joint through a servo motor, so that the movement precision is improved.
The rotating pair can be a rigid hinge or a flexible hinge, so that two connected rod pieces can rotate relatively around the axis of the hinge, and two hinges forming the rotating pair are respectively connected with one connecting rod.
And the seventh revolute pair is respectively connected with the upper platform and the lower platform through connecting rods.
Compared with the prior art, the invention destroys the rotation condition by changing the position of the third revolute pair axis in the first branched chain, and has the following advantages:
1. controllable rigidity can be realized: the mechanism can rotate only when the axes of the two revolute pairs are coaxial, and cannot rotate when the axes of the two revolute pairs are not coaxial. The axes of the first rotating pair, the third rotating pair and the sixth rotating pair are intersected at a point and are equivalent to a ball hinge, and the rotating axis of the ball hinge is coaxial with the axis of the seventh rotating pair on the right side in an initial state, so that the rotating condition is met. The second revolute pair, the third revolute pair, the fourth revolute pair and the fifth revolute pair form a four-bar mechanism, when the whole mechanism rotates to a certain angle, the axis of the third revolute pair is driven by the driving force added to the second revolute pair, so that the axis of the first revolute pair, the axis of the third revolute pair and the axis of the sixth revolute pair are not converged, the coaxial condition is not met, the rigidity of the mechanism is increased at the moment, the controllability of the rigidity is realized, and the mechanism is locked at the same time.
2. The purpose that the mechanism does not rotate any more under any bending angle can be realized: the mechanism can rotate only when the axes of the two revolute pairs are coaxial, and cannot rotate when the axes of the two revolute pairs are not coaxial. The axes of the first rotating pair, the third rotating pair and the sixth rotating pair are intersected at a point and are equivalent to a spherical hinge, and the axis of the spherical hinge is coaxial with the axis of the seventh rotating pair on the right side in an initial state, so that the rotating condition is met. When the whole mechanism rotates to a certain angle, the axis of the third revolute pair is driven by the driving force added to the second revolute pair, so that the axis of the third revolute pair is changed, the axes of the first revolute pair, the third revolute pair and the sixth revolute pair are not converged, the coaxial condition is not met, and the mechanism is locked.
3. Simple to operate, inertia are little, and the motion response is fast: the joint structure of the invention is connected by the rod pieces with smaller size, so the whole size of the joint is also small, and the motion of the joint is controlled by the servo motor, so the joint structure has smaller moment of inertia.
Drawings
FIG. 1 is a schematic structural view of the present invention;
fig. 2 is a schematic diagram of the present invention.
In the figure, 1-upper platform, 2-lower platform, 12-seventh revolute pair, 13-first revolute pair, 14-sixth revolute pair, 15-third revolute pair, 16-second revolute pair, 17-fourth revolute pair, 18-fifth revolute pair, 19-first connecting rod, 20-second connecting rod, 21-third connecting rod, 22-fourth connecting rod and 23-fifth connecting rod.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.
Examples
A mechanical arm joint with controllable rigidity is structurally shown in figure 1 and comprises an upper platform 1, a lower platform 2, a first moving branch chain and a second moving branch chain, wherein the first moving branch chain and the second moving branch chain are connected between the upper platform and the lower platform.
The first moving branched chain comprises a first revolute pair 13, a second revolute pair 16, a third revolute pair 15, a fourth revolute pair 17, a fifth revolute pair 18 and a sixth revolute pair 14; the sixth revolute pair 14 and the seventh revolute pair 12 are connected with the upper platform 1, and the first revolute pair 13 and the seventh revolute pair 12 are connected with the lower platform 2. The second kinematic branched chain comprises a fifth seventh revolute pair 16; the fifth revolute pair 18 is connected to the first revolute pair 14 by a first link 19, and the fifth revolute pair 18 is connected to the sixth revolute pair 17 by a second link 20. The sixth revolute pair 17 is connected with the third revolute pair 15 through a third connecting rod 21, the third revolute pair 15 is connected with the seventh revolute pair 16 through a fourth connecting rod 22, and the seventh revolute pair 16 is connected with the second revolute pair 13 through a fifth connecting rod 23; the first revolute pair 13 is connected with the second revolute pair 16 through a fifth connecting rod 23, the second revolute pair 16 is connected with the third revolute pair 15 through a fourth connecting rod 22, the third revolute pair 15 is connected with the fourth revolute pair 17 through a third connecting rod 21, the fourth revolute pair 17 is connected with the fifth revolute pair 18 through a second connecting rod 20, and the fifth revolute pair 18 is connected with the sixth revolute pair 14 through a first connecting rod; the second moving branched chain comprises a seventh revolute pair; the seventh revolute pair 12 is connected with the upper platform 1 and the lower platform 2 through connecting rods respectively.
The axis of the first revolute pair 13, the axis of the third revolute pair 15 and the axis of the sixth revolute pair 14 intersect at a point on the extension line of the axis of the seventh revolute pair 12. The axes of the second revolute pair 16, the fourth revolute pair 17 and the fifth revolute pair 118 are parallel to the axis of the seventh revolute pair 12, and the axis of the third revolute pair 15 is not in the same plane as the axes of the other revolute pairs.
The working principle of the invention can be explained as follows in connection with fig. 2:
when the axes of the first revolute pair 13, the third revolute pair 15 and the sixth revolute pair 14 in the first kinematic branched chain meet at a point, which is equivalent to a meeting revolute pair, or is equivalent to a spherical hinge, and the meeting point is on the extension line of the axis of the seventh revolute pair 12, namely, the axes of the first revolute pair 13, the third revolute pair 15, the sixth revolute pair 14 and the seventh revolute pair 18 meet at a point in space, the coaxial condition is satisfied, so when the seventh revolute pair 18 rotates, the mechanism can rotate around the axis of the seventh revolute pair 18. The axes of the first rotating pair, the third rotating pair and the sixth rotating pair are intersected at one point. And in the initial state, the rotation axis of the ball hinge is coaxial with the axis of the seventh right revolute pair, so that the rotation condition is met. The second revolute pair 16, the third revolute pair 15, the fourth revolute pair 17 and the fifth revolute pair 18 form a four-bar mechanism, when the whole mechanism rotates to a certain angle, the axis of the third revolute pair 15 is driven by a driving force added to the second revolute pair 16 to change, so that the axes of the first revolute pair 13, the third revolute pair 15 and the sixth revolute pair 14 do not meet the coaxial condition any more, the rigidity of the mechanism is increased at the moment, the rigidity is controlled, and the mechanism is locked.
When the second revolute pair 16 in the first kinematic branched chain is rotated by the motor, the position of the axis of the third revolute pair 15 is changed, so that the space of the axis of the first revolute pair 13, the axis of the third revolute pair 15, the axis of the sixth revolute pair 14 and the axis of the seventh revolute pair 12 do not meet the coaxial condition any more, the mechanism can not rotate any more, the rigidity is increased, and the controllable rigidity is realized.
The embodiments described above are described to facilitate an understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.
Claims (4)
1. A mechanical arm joint with controllable rigidity comprises an upper platform, a lower platform, a first moving branch chain and a second moving branch chain, wherein the first moving branch chain and the second moving branch chain are connected between the upper platform and the lower platform,
the method is characterized in that:
the first moving branched chain comprises a first revolute pair, a second revolute pair, a third revolute pair, a fourth revolute pair, a fifth revolute pair and a sixth revolute pair,
the sixth revolute pair is connected with the upper platform, the first revolute pair is connected with the lower platform, the fifth revolute pair is respectively connected with the fourth revolute pair and the sixth revolute pair through two connecting rods, the third revolute pair is respectively connected with the second revolute pair and the fourth revolute pair through two connecting rods, the second revolute pair is connected with the first revolute pair through a connecting rod,
the second moving branched chain comprises a seventh revolute pair, and the second moving branched chain is connected with the upper platform and the lower platform respectively;
the axes of the first rotating pair, the third rotating pair and the sixth rotating pair are intersected at a point which is positioned on the axis extension line of the seventh rotating pair;
the axes of the second revolute pair, the fourth revolute pair and the fifth revolute pair are parallel to the axis space of the seventh revolute pair;
the axis of the third revolute pair is not in the same plane with the axes of other revolute pairs;
the axes of the first rotating pair, the third rotating pair and the sixth rotating pair are not on the same plane, and the spaces are converged at one point.
2. A manipulator joint with controlled stiffness according to claim 1, wherein the revolute pair is a rigid hinge or a flexible hinge.
3. The mechanical arm joint with controllable rigidity as claimed in claim 2, wherein the two hinges forming the revolute pair are respectively connected with a connecting rod.
4. The mechanical arm joint with controllable rigidity as claimed in claim 1, wherein the seventh revolute pair is connected with the upper platform and the lower platform respectively through connecting rods.
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| CN201910239794.XA CN109849047B (en) | 2019-03-27 | 2019-03-27 | Mechanical arm joint with controllable rigidity |
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| CN201910239794.XA CN109849047B (en) | 2019-03-27 | 2019-03-27 | Mechanical arm joint with controllable rigidity |
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| CN109849047B true CN109849047B (en) | 2021-09-10 |
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Citations (7)
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| US6047610A (en) * | 1997-04-18 | 2000-04-11 | Stocco; Leo J | Hybrid serial/parallel manipulator |
| WO2003078111A1 (en) * | 2002-03-18 | 2003-09-25 | Abb Ab | Manipulator and method involving a manipulator for movement of an object, comprising at least two driving parallel kinematic connecting chains |
| CN1803410A (en) * | 2006-01-18 | 2006-07-19 | 河北工业大学 | Two freedom degrees decoupling sphere parallel mechanism |
| CN102275162A (en) * | 2011-07-08 | 2011-12-14 | 常州大学 | Three-rotation spherical surface parallel operation device |
| CN105234922A (en) * | 2015-10-08 | 2016-01-13 | 南昌大学 | Three-degree of freedom (DOF) translational and one-DOF rotational parallel robot device |
| CN105881494A (en) * | 2014-11-07 | 2016-08-24 | 江南大学 | Decoupling hybrid mechanism with five freedom degrees of 1T&(2T)&2R |
| CN206825405U (en) * | 2017-04-07 | 2018-01-02 | 河南科技大学 | Isotropic space two degrees of freedom rotating parallel device people |
-
2019
- 2019-03-27 CN CN201910239794.XA patent/CN109849047B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6047610A (en) * | 1997-04-18 | 2000-04-11 | Stocco; Leo J | Hybrid serial/parallel manipulator |
| WO2003078111A1 (en) * | 2002-03-18 | 2003-09-25 | Abb Ab | Manipulator and method involving a manipulator for movement of an object, comprising at least two driving parallel kinematic connecting chains |
| CN1803410A (en) * | 2006-01-18 | 2006-07-19 | 河北工业大学 | Two freedom degrees decoupling sphere parallel mechanism |
| CN102275162A (en) * | 2011-07-08 | 2011-12-14 | 常州大学 | Three-rotation spherical surface parallel operation device |
| CN105881494A (en) * | 2014-11-07 | 2016-08-24 | 江南大学 | Decoupling hybrid mechanism with five freedom degrees of 1T&(2T)&2R |
| CN105234922A (en) * | 2015-10-08 | 2016-01-13 | 南昌大学 | Three-degree of freedom (DOF) translational and one-DOF rotational parallel robot device |
| CN206825405U (en) * | 2017-04-07 | 2018-01-02 | 河南科技大学 | Isotropic space two degrees of freedom rotating parallel device people |
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