Metamorphic five-rod mechanism
Technical Field
The invention relates to the technical field of robots, in particular to a metamorphic five-rod mechanism.
Background
The traditional mechanical equipment is generally fixed-freedom equipment with a single operation mode, but with the development of scientific technology, particularly industrial production and special application environments such as high-risk and aerospace engineering, a mechanism is required to have good adaptability and variable structure characteristics, and the mechanism is expected to change the degree of freedom and the operation mode according to the change of the operation environment or operation task.
Disclosure of Invention
The invention aims to provide a metamorphic five-rod mechanism, which solves the problems that the traditional machine only has the fixed freedom degree of a single operation mode, and has poor adaptability and deformability.
In order to solve the technical problems, the invention adopts the following technical scheme:
the metamorphic five-bar mechanism comprises a rack, two spherical five-bar mechanisms, two connecting bars and two connecting rods, wherein the spherical five-bar mechanisms comprise a first spherical five-bar mechanism and a second spherical five-bar mechanism which are arranged in parallel and connected to the rack, the first spherical five-bar mechanism and the second spherical five-bar mechanism are respectively connected with a first connecting bar and a second connecting bar, the first connecting bar is connected with the first connecting rod through a sixth rotating pair, the second connecting bar is connected with the second connecting rod through a seventh rotating pair, and the top ends of the first connecting bar and the second connecting bar are connected through an eighth rotating pair.
Further, the first spherical five-bar mechanism comprises a first straight bar A and a second straight bar A which are vertically fixed on the rack; the end of the first straight rod A is connected with one end of a first bent rod A through a first revolute pair A, and the end of the second straight rod A is connected with one end of a second bent rod A through a second revolute pair A; the other end of the first bent rod A is connected with one end of a third bent rod A through a third revolute pair A, the other end of the second bent rod A is connected with one end of a fourth bent rod A through a fourth revolute pair A, and the other end of the fourth bent rod A is connected with the other end of the third bent rod A through a fifth revolute pair A; the bend angles of the first bent rod A, the second bent rod A, the third bent rod A and the fourth bent rod A are all 90 degrees; the lower end of the first connecting rod 4 is fixed at the corner of the fourth bent rod A, and the first connecting rod is upward vertical to the plane of the fourth bent rod A;
the second spherical surface five-bar mechanism has the same structure as the first spherical surface five-bar mechanism and comprises a first straight bar B and a second straight bar B which are vertically fixed on the rack; the end of the first straight rod B is connected with one end of a first bent rod B through a first revolute pair B, and the end of the second straight rod B is connected with one end of a second bent rod B through a second revolute pair B; the other end of the first bent rod B is connected with one end of a third bent rod B through a third revolute pair B, the other end of the second bent rod B is connected with one end of a fourth bent rod B through a fourth revolute pair B, and the other end of the fourth bent rod B is connected with the other end of the third bent rod B through a fifth revolute pair B; the bend angles of the first bent rod B, the second bent rod B, the third bent rod B and the fourth bent rod B are all 90 degrees; the lower end of the second side link is fixed at the corner of the fourth bent rod B, and the second side link is upward vertical to the plane of the fourth bent rod B;
the axes of the sixth revolute pair, the seventh revolute pair, the eighth revolute pair, the fourth revolute pair A and the fourth revolute pair B are parallel, the second revolute pair A and the second revolute pair B are coaxially arranged and have the same rotation angle, and the axes of the first revolute pair A and the first revolute pair B are parallel.
Still further, the first side link and the second side link have the same specification, and the first connecting rod and the second connecting rod have the same specification.
Still further, two clearance holes are formed in the rack and located right below the first spherical five-bar mechanism and the second spherical five-bar mechanism.
Compared with the prior art, the invention has the beneficial technical effects that:
the metamorphic five-bar mechanism comprises a rack, two spherical five-bar mechanisms, two side link rods and two connecting rods, wherein the two connecting rods are connected with the two spherical five-bar mechanisms through the two side link rods, the connecting rods are connected with the side link rods through revolute pairs, and two adjacent connecting rods are connected through the revolute pairs; the invention has ingenious conception and compact and reasonable structure, the two spherical five-rod mechanisms are arranged on the rack side by side, the rotating amplitude of the spherical five-rod mechanism connected with the rack is selected as an input pair, and the metamorphic five-rod mechanism can be correspondingly switched into five different operation modes by selectively driving or locking the rotating pair on the spherical five-rod mechanism connected with the rack.
Drawings
The invention is further illustrated in the following description with reference to the drawings.
FIG. 1 is a schematic view of an initial orientation of a metamorphic five-bar mechanism according to the present invention;
FIG. 2 is a schematic view of the metamorphic five-bar mechanism operating mode A of the present invention;
FIG. 3 is a schematic view of the metamorphic five-bar mechanism operating mode B of the present invention;
FIG. 4 is a schematic view of the metamorphic five-bar mechanism operating mode C of the present invention;
FIG. 5 is a schematic view of the metamorphic five-bar mechanism operating mode D of the present invention;
FIG. 6 is a schematic view of the metamorphic five-bar mechanism operating mode E of the present invention;
description of reference numerals: 1. a frame;
2. a first spherical five-bar mechanism; 201. a first straight bar A; 202. a second straight rod A; 203. a first revolute pair A; 204. a first curved bar A; 205. a second revolute pair A; 206. a second curved bar A; 207. a third revolute pair A; 208. a third curved bar A; 209. a fourth revolute pair A; 210. a fourth curved bar A; 211. a fifth revolute pair A;
3. a second spherical five-bar mechanism; 301. a first straight bar B; 302. a second straight rod B; 303. a first revolute pair B; 304. a first curved bar B; 305. a second revolute pair B; 306. a second curved bar B; 307. a third revolute pair B; 308. a third curved bar B; 309. a fourth revolute pair B; 310. a fourth curved bar B; 311. a fifth revolute pair B;
4. a first link lever; 5. a first link; 6. a second link; 7. a second side link; 8. a sixth revolute pair; 9. a seventh revolute pair; 10. and an eighth revolute pair. Detailed Description
As shown in fig. 1, a metamorphic five-bar mechanism includes a frame 1, two spherical five-bar mechanisms, two link levers and two connecting bars, where the spherical five-bar mechanism includes two first spherical five-bar mechanisms 2 and two second spherical five-bar mechanisms 3 arranged in parallel and connected to the frame 1, the first spherical five-bar mechanisms 2 and the second spherical five-bar mechanisms 3 are respectively connected with a first link lever 4 and a second link lever 7, the first link lever 4 is connected with a first connecting bar 5 through a sixth revolute pair 8, the second link lever 7 is connected with a second connecting bar 6 through a seventh revolute pair 9, and top ends of the first connecting bar 5 and the second connecting bar 6 are connected through an eighth revolute pair 10.
Specifically, the first spherical five-bar mechanism 2 comprises a first straight bar a201 and a second straight bar a202 which are vertically fixed on the rack 1; the end of the first straight rod A201 is connected with one end of a first bent rod A204 through a first revolute pair A203, and the end of the second straight rod A202 is connected with one end of a second bent rod A206 through a second revolute pair A205; the other end of the first bent rod a204 is connected with one end of a third bent rod a208 through a third revolute pair a207, the other end of the second bent rod a206 is connected with one end of a fourth bent rod a210 through a fourth revolute pair a209, and the other end of the fourth bent rod a210 is connected with the other end of the third bent rod a208 through a fifth revolute pair a 211; the bend angles of the first bent rod A204, the second bent rod A206, the third bent rod A208 and the fourth bent rod A210 are all 90 degrees; the lower end of the first connecting rod 4 is fixed at the corner of the fourth curved rod a210, and the first connecting rod 4 is upward perpendicular to the plane of the fourth curved rod a 210; the axes of the first revolute pair a203, the second revolute pair a205, the third revolute pair a207, the fourth revolute pair a209 and the fifth revolute pair a211 all pass through the same rotation center point O, and the loci of all points on all the members of the first spherical five-bar mechanism 2 are spherical curves centered on the point O.
The second spherical five-bar mechanism 3 has the same structure as the first spherical five-bar mechanism 2, and comprises a first straight bar B301 and a second straight bar B302 which are vertically fixed on the rack 1; the end of the first straight rod B301 is connected with one end of a first bent rod B304 through a first revolute pair B303, and the end of the second straight rod B302 is connected with one end of a second bent rod B306 through a second revolute pair B305; the other end of the first bent rod B304 is connected with one end of a third bent rod B308 through a third revolute pair B307, the other end of the second bent rod B306 is connected with one end of a fourth bent rod B310 through a fourth revolute pair B309, and the other end of the fourth bent rod B310 is connected with the other end of the third bent rod B308 through a fifth revolute pair B311; the bending angles of the first bent rod B304, the second bent rod B306, the third bent rod B308 and the fourth bent rod B310 are all 90 degrees; the lower end of the second side link 7 is fixed at the corner of the fourth curved bar B310, and the second side link 7 is upward perpendicular to the plane of the fourth curved bar B310; the axes of the first revolute pair B303, the second revolute pair B305, the third revolute pair B307, the fourth revolute pair B309 and the fifth revolute pair B311 all pass through the same rotation center O ', and the loci of all points on all the members of the second spherical five-bar mechanism are spherical curves centered on the O' point.
The axes of the sixth revolute pair 8, the seventh revolute pair 9, the eighth revolute pair 10, the fourth revolute pair a209 and the fourth revolute pair B309 are parallel, the second revolute pair a205 and the second revolute pair B305 are coaxially arranged and have the same rotation angle, and the axes of the first revolute pair a203 and the first revolute pair B303 are parallel.
The first side link 4 and the second side link 7 have the same specification, and the first connecting rod 5 and the second connecting rod 6 have the same specification. Two clearance holes are formed in the rack 1 and are located right below the first spherical five-bar mechanism 2 and the second spherical five-bar mechanism 3.
A first revolute pair A203, a first revolute pair B303 and a second revolute pair A205 (or a second revolute pair B305) which are connected with a frame 1 are selected as input pairs of the metamorphic five-rod mechanism, the rotation angle of the first revolute pair A203 is set to be alpha, the rotation angle of the first revolute pair B303 is set to be gamma, and the rotation angle of the second revolute pair A205 and the second revolute pair B305 is set to be beta.
In the initial configuration shown in fig. 1, α ═ β ═ γ ═ 0 °, the first side link 4 and the second side link 7 are perpendicular to the gantry 1. In the initial configuration, the second revolute pair a205, the fifth revolute pair a211, the second revolute pair B305 and the fifth revolute pair B311 are coaxial, the first revolute pair a203 and the fourth revolute pair a209 are coaxial, and the first revolute pair B303 and the fourth revolute pair B309 are coaxial.
As shown in fig. 1, a reference coordinate system O-xyz is established at the point O of the rotation center of the first spherical five-bar mechanism, the x axis of the reference coordinate system is coaxial with the first revolute pair a203, the y axis of the reference coordinate system is coaxial with the second revolute pair a205, and the z axis of the reference coordinate system is determined by the cross product of the x axis and the y axis.
As shown in FIG. 2, the metamorphic five-bar mechanism is shown in the operating mode A. When α ≠ 0 °, β ≠ 0 °, and γ ≠ 0 °, that is, when the input pairs are the first revolute pair a203, the first revolute pair B303, and the second revolute pair a205 (or the second revolute pair B305) simultaneously driven, the cell-changing five-bar mechanism is switched from the initial configuration to the operation mode a. If the first link 5 is selected as the output member of the metamorphic five-bar mechanism, in the operation mode a, the number of degrees of freedom of the first link 5 is 3, and the nature of the degrees of freedom is two continuous rotations and one continuous movement, namely 2R1T movement (when representing movement, the letter R represents rotation and the letter T represents movement). The rotation axes are respectively a y axis and a [ cos beta 0-sin beta ] T axis, and the moving direction is [ sin beta sin alpha cos beta cos alpha cos beta sin alpha ] T.
FIG. 3 shows the metamorphic five bar mechanism in operation mode B. When α ≠ 0 °, γ ≠ 0 °, and the second revolute pair a205 and the second revolute pair B305 are locked at β ═ 0 °, the metamorphic five-bar mechanism is switched from the initial configuration to the operation mode B. If the first link 5 is selected as the output member of the mechanism, in the operation mode B, the number of degrees of freedom of the first link 5 is 2, and the properties of the degrees of freedom are continuous rotation around the x-axis and movement in the [0cos α sin α ] T direction. In the operation mode B, the metamorphic five-bar mechanism is changed to the planar 5R mechanism.
FIG. 4 shows the metamorphic five bar mechanism in operation mode C. When β ≠ 0 ° and α ≠ γ ═ 0 ° locks the first revolute pair a203 and the first revolute pair B303, the metamorphic five-bar mechanism switches from the initial configuration to the operation mode C. If the first link 5 is selected as the output member of the mechanism, in the operation mode C, the number of degrees of freedom of the first link 5 is 1, and the nature of the degrees of freedom is continuous rotation around the y-axis. And in the operation mode C, the metamorphic five-rod mechanism integrally rotates around the y axis, and the metamorphic five-rod mechanism is equivalent to a revolute pair with the rotating shaft as the y axis.
FIG. 5 shows the metamorphic five-bar mechanism in the operating mode D. When α ≠ 0 °, β ≠ 0 °, and the first rotation pair B303 is locked at γ ═ 0 °, the metamorphic five-bar mechanism is switched from the initial configuration to the operation mode D. If the first link 5 is selected as the output member of the mechanism, the number of degrees of freedom of the first link 5 in the operation mode D is 2.
FIG. 6 shows the metamorphic five bar mechanism in the operating mode E. When α ≠ 0 ° and the second revolute pair a205 and the first revolute pair B303 are locked at β ≠ 0 °, the metamorphic five-bar mechanism switches from the initial configuration to the operation mode E. If the first link 5 is selected as the output member of the mechanism, the number of degrees of freedom of the first link 5 in the operation mode E is 1. In the operation mode E, the metamorphic five-bar mechanism is changed to the planar 4R mechanism.
The metamorphic five-rod mechanism can be used as a metamorphic unit to be applied to the design of a reconfigurable parallel mechanism, and the metamorphic five-rod mechanism can also be used as a robot manipulator to be applied to engineering practice.
The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.