CN114012709A - Four-degree-of-freedom parallel robot with variable-rod-length parallelogram closed-loop subchain - Google Patents

Abstract

The invention relates to a four-degree-of-freedom parallel robot with a variable-rod-length parallelogram closed-loop subchain, which comprises a rack, a first branched chain, a second branched chain, a third branched chain, a fourth branched chain, a first motor, a second motor, a third motor, a fourth motor and a movable platform. The first branched chain, the second branched chain, the third branched chain and the fourth branched chain are distributed at 90 degrees, the first motor, the second motor, the third motor and the fourth motor are fixed on the rack and are respectively connected with the first branched chain, the second branched chain, the third branched chain and the fourth branched chain, and the first branched chain, the second branched chain and the third branched chain are respectively connected with the movable platform. The four-degree-of-freedom parallel robot with the variable-rod-length parallelogram closed-loop subchain can realize the motion of the movable platform in three-dimensional translation and one-dimensional rotation in space.

Description

Four-degree-of-freedom parallel robot with variable-rod-length parallelogram closed-loop subchain

Technical Field

The invention relates to the field of industrial robots, in particular to a four-degree-of-freedom parallel robot with a variable-rod-length parallelogram closed-loop subchain.

Background

The parallel robot and the serial robot together form an important part of the industrial robot, the parallel robot has the advantages of high rigidity, high speed, strong flexibility, light weight and the like, is most widely applied to light industries such as food, medicine, electronics and the like, and has incomparable advantages in the aspects of material handling, packaging, sorting and the like. With the increasingly wide application of parallel robots in the market, the parallel robots become new forces for the growth of industrial robots. The parallel robot is a closed loop system consisting of a dynamic platform, a static platform and two or more independent motion branched chains connecting the dynamic platform and the static platform, and compared with the traditional serial robot, the parallel robot has the advantages of no error accumulation, high motion precision, small motion inertia, good dynamic property and the like, and the drive can be arranged near the static platform.

At present, a four-degree-of-freedom parallel robot with three-translation and one-rotation freedom degree has wide application in the industrial fields of material moving, surface assembly, part processing and the like. In order to meet more industrial requirements, mechanisms such as H4, I4, Heli4 and Par4 with four branches are successively invented, wherein an H4 type parallel mechanism which has four branches and a double-acting platform and can realize SCARA movement is successfully commercialized, and typically represents products such as Adept Quattro series, but the parallel mechanism has the characteristics of multiple moving components, complex kinematics and the like. In addition, the university of Qinghua also provides a symmetrical four-branched-chain four-degree-of-freedom parallel mechanism which is simple in structure, provided with a single-action platform and small in working space. The four branched chains are adopted to connect the rack and each branched chain of the movable platform comprises the telescopic parallelogram closed-loop subchain, the movable platform can complete the motion of three-dimensional translation and one-dimensional rotation in space, and the movable platform has the advantages of simple structure, large working space, high precision, high speed and the like.

Disclosure of Invention

The invention provides a four-freedom parallel robot capable of realizing three-dimensional translation and one-dimensional rotation for solving the technical problems in the prior art.

In order to achieve the purpose of the invention, the invention adopts the following technical scheme:

the four-degree-of-freedom parallel robot with the variable-rod-length parallelogram closed-loop subchain comprises a rack 0, a first branched chain 1, a second branched chain 2, a third branched chain 3, a fourth branched chain 4, a first motor 110, a second motor 210, a third motor 310, a fourth motor 410 and a movable platform 5.

The first support chain 1 comprises a first driving rod 112, a first connecting rod 116, a second connecting rod 117, a third connecting rod 120, a fourth connecting rod 121, a first connecting piece 122 and a second connecting piece 113, wherein the first connecting rod 116 is connected with the first driving rod 112 through a first revolute pair 114, the second connecting rod 117 is connected with the first driving rod 112 through a second revolute pair 115, the first connecting piece 122 is connected with the first connecting rod 116 through a third revolute pair 123, the first connecting piece 122 is connected with the second connecting rod 117 through a fourth revolute pair 124, the third connecting rod 120 is connected with the first connecting rod 116 through a first revolute pair 118, the fourth connecting rod 121 is connected with the second connecting rod 117 through a second revolute pair 119, the second connecting piece 113 is connected with the third connecting rod 120 through a first spherical hinge 125, and the second connecting piece 113 is connected with the fourth connecting rod 121 through a second spherical hinge 126; the first active lever 112 of the first branched chain 1 is connected with the first motor 110 through a first zero rotation pair 111, the first motor 110 is fixed on the frame 0, the second connecting member 113 of the first support chain 1 is connected with the movable platform 5 through a zero-two revolute pair 51, the axis of the first zero-two revolute pair 111 is perpendicular to the axis of the first revolute pair 114, the axis of the first zero-two revolute pair 111 is perpendicular to the axis of the second revolute pair 115, the axes of the first revolute pair 114, the second revolute pair 115, the third revolute pair 123 and the fourth revolute pair 124 are parallel to each other, the distance between the axes of the first revolute pair 114 and the second revolute pair 115 is equal to the distance between the center of the first spherical hinge 125 and the center of the second spherical hinge 126, and the distance between the center of the first spherical hinge 125 and the axis of the first revolute pair 114 is equal to the distance between the center of the second spherical hinge 126 and the axis of the second revolute pair 115.

The second branched chain 2 comprises a second driving rod 212, a fifth connecting rod 216, a sixth connecting rod 217, a seventh connecting rod 220, an eighth connecting rod 221, a third connecting piece 222 and a fourth connecting piece 213, the fifth connecting rod 216 is connected with the second driving rod 212 through a fifth revolute pair 214, the sixth connecting rod 217 is connected with the second driving rod 212 through a sixth revolute pair 215, the third connecting piece 222 is connected with the fifth connecting rod 216 through a seventh revolute pair 223, the third connecting piece 222 is connected with the sixth connecting rod 217 through an eighth revolute pair 224, the seventh connecting rod 220 is connected with the fifth connecting rod 216 through a third revolute pair 218, the eighth connecting rod 221 is connected with the sixth connecting rod 217 through a fourth revolute pair 219, the fourth connecting piece 213 is connected with the seventh connecting rod 220 through a third spherical hinge 225, and the fourth connecting piece 213 is connected with the eighth connecting rod 221 through a fourth spherical hinge 226; the second driving rod 212 of the second branched chain 2 is connected with the second motor 210 through the second zero-one revolute pair 211, the second motor 210 is fixed on the frame 0, the fourth connecting member 213 of the second branched chain 2 is connected with the movable platform 5 through a second zero-two revolute pair 52, the axis of the second zero-two revolute pair 211 is perpendicular to the axis of the fifth revolute pair 214, the axis of the second zero-two revolute pair 211 is perpendicular to the axis of the sixth revolute pair 215, the axes of the fifth revolute pair 214, the sixth revolute pair 215, the seventh revolute pair 223 and the eighth revolute pair 224 are parallel to each other, the distance between the axis of the fifth revolute pair 214 and the axis of the sixth revolute pair 215 is equal to the distance between the center of the third spherical hinge 225 and the center of the fourth spherical hinge 226, and the distance between the center of the third spherical hinge 225 and the axis of the fifth revolute pair 214 is equal to the distance between the center of the fourth spherical hinge 226 and the axis of the sixth revolute pair 215.

The third branched chain 3 includes a third driving rod 312, a ninth connecting rod 316, a tenth connecting rod 317, an eleventh connecting rod 320, a twelfth connecting rod 321, a fifth connecting rod 322, and a sixth connecting rod 313, the ninth connecting rod 316 is connected to the third driving rod 312 through a ninth revolute pair 314, the tenth connecting rod 317 is connected to the third driving rod 312 through a tenth revolute pair 315, the fifth connecting rod 322 is connected to the ninth connecting rod 316 through an eleventh revolute pair 323, the fifth connecting rod 322 is connected to the tenth connecting rod 317 through a twelfth revolute pair 324, the eleventh connecting rod 320 is connected to the ninth connecting rod 316 through a fifth revolute pair 318, the twelfth connecting rod 321 is connected to the tenth connecting rod 317 through a sixth revolute pair 319, the sixth connecting rod 313 is connected to the eleventh connecting rod 320 through a fifth spherical hinge 325, and the sixth connecting rod 313 is connected to the twelfth connecting rod 321 through a sixth spherical hinge 326; the third driving rod 312 of the third branched chain 3 is connected with the third motor 310 through a third zero-first rotating pair 311, the third motor 310 is fixed on the frame 0, the sixth connecting part 313 of the third branched chain 3 is connected with the movable platform 5 through a third zero-second rotating pair 53, the axis of the third zero rotating pair 311 is perpendicular to the axis of the ninth rotating pair 314, the axis of the third zero rotating pair 311 is perpendicular to the axis of the tenth rotating pair 315, the axes of the ninth rotating pair 314, the tenth rotating pair 315, the eleventh rotating pair 323 and the twelfth rotating pair 324 are parallel to each other, the distance between the axis of the ninth rotating pair 314 and the axis of the tenth rotating pair 315 is equal to the distance between the axis of the eleventh rotating pair 323 and the axis of the twelfth rotating pair 324, the distance between the axis of the ninth rotating pair 314 and the axis of the tenth rotating pair 315 is equal to the distance between the center of the fifth spherical hinge 325 and the center of the sixth spherical hinge 326, the distance between the center of the fifth spherical hinge 325 and the axis of the ninth rotating pair 314 is equal to the distance between the center of the sixth spherical hinge 315 .

The fourth branched chain 4 includes a fourth driving rod 412, a thirteenth connecting rod 416, a fourteenth connecting rod 417, a fifteenth connecting rod 420, a sixteenth connecting rod 421, a seventh connecting member 422, and an eighth connecting member 413, the thirteenth connecting rod 416 is connected to the fourth driving rod 412 through a thirteenth rotating pair 414, the fourteenth connecting rod 417 is connected to the fourth driving rod 412 through a fourteenth rotating pair 415, the seventh connecting member 422 is connected to the thirteenth connecting rod 416 through a fifteenth rotating pair 423, the seventh connecting member 422 is connected to the fourteenth connecting rod 417 through a sixteenth rotating pair 424, the fifteenth connecting rod 420 is connected to the thirteenth connecting rod 416 through a seventh moving pair 418, the sixteenth connecting rod 421 is connected to the fourteenth connecting rod 417 through an eighth moving pair 419, the eighth connecting member 413 is connected to the fifteenth connecting rod 420 through a seventh spherical hinge 425, and the eighth connecting member 413 is connected to the sixteenth connecting rod 421 through an eighth spherical hinge 426; the fourth driving rod 412 of the fourth branched chain 4 is connected with the fourth motor 410 through a fourth zero-first revolute pair 411, the fourth motor 410 is fixed on the frame 0, the eighth connecting piece 413 of the fourth branched chain 4 is connected with the movable platform 5 through a fourth zero-second revolute pair 54, the axis of the fourth zero revolute pair 411 is perpendicular to the axis of the thirteenth revolute pair 414, the axis of the fourth zero revolute pair 411 is perpendicular to the axis of the fourteenth revolute pair 415, the axes of the thirteenth revolute pair 414, the fourteenth revolute pair 415, the fifteenth revolute pair 423 and the sixteenth revolute pair 424 are parallel to each other, the distance between the axis of the thirteenth revolute pair 414 and the axis of the fourteenth revolute pair 415 is equal to the distance between the axis of the fifteenth revolute pair 423 and the axis of the sixteenth revolute pair 424, the distance between the axis of the thirteenth revolute pair 414 and the axis of the fourteenth revolute pair 415 is equal to the distance between the center of the seventh spherical hinge 425 and the center of the eighth spherical hinge 426, and the distance between the center of the thirteenth spherical hinge 425 and the thirteenth revolute pair 414 is equal to the center of the fourteenth spherical hinge 426 The distance between the axes of the kinematic pairs 415 is equal.

Compared with the prior art, the invention has the following obvious and prominent substantive characteristics and remarkable advantages:

1. the four-degree-of-freedom parallel robot with the variable-rod-length parallelogram closed-loop subchain has the advantages of simple and symmetrical structure, small motion inertia of a mechanism and good dynamic performance because the driving device is arranged on the rack;

2. the device has the advantages of simple structure, high speed and flexible movement capability, and various actuators can be installed on the movable platform, so the device is easy to popularize and apply.

Drawings

FIG. 1 is a schematic structural diagram of a four-degree-of-freedom parallel robot with a variable-rod-length parallelogram closed-loop subchain.

Fig. 2 is a schematic diagram of a first branch chain structure of a four-degree-of-freedom parallel robot with a variable-rod-length parallelogram closed-loop subchain according to the invention.

FIG. 3 is a schematic diagram of a structure of a second branched chain of a four-degree-of-freedom parallel robot with a variable-rod-length parallelogram closed-loop subchain according to the present invention.

FIG. 4 is a schematic diagram of a structure of a third branched chain of a four-degree-of-freedom parallel robot with a variable-rod-length parallelogram closed-loop subchain.

FIG. 5 is a schematic diagram of a fourth branched chain structure of a four-degree-of-freedom parallel robot with a variable-rod-length parallelogram closed-loop subchain according to the present invention.

FIG. 6 is a schematic structural diagram of a four-degree-of-freedom parallel robot moving platform containing a variable-rod-length parallelogram closed-loop subchain according to the invention.

Detailed Description

The technical solution of the present invention is further explained with reference to the drawings and the embodiments.

Referring to fig. 1 to 6, the four-degree-of-freedom parallel robot including the variable-rod-length parallelogram closed-loop subchain includes a frame 0, a first branch chain 1, a second branch chain 2, a third branch chain 3, a fourth branch chain 4, a first motor 110, a second motor 210, a third motor 310, a fourth motor 410, and a moving platform 5.

The first support chain 1 comprises a first driving rod 112, a first connecting rod 116, a second connecting rod 117, a third connecting rod 120, a fourth connecting rod 121, a first connecting piece 122 and a second connecting piece 113, wherein the first connecting rod 116 is connected with the first driving rod 112 through a first revolute pair 114, the second connecting rod 117 is connected with the first driving rod 112 through a second revolute pair 115, the first connecting piece 122 is connected with the first connecting rod 116 through a third revolute pair 123, the first connecting piece 122 is connected with the second connecting rod 117 through a fourth revolute pair 124, the third connecting rod 120 is connected with the first connecting rod 116 through a first revolute pair 118, the fourth connecting rod 121 is connected with the second connecting rod 117 through a second revolute pair 119, the second connecting piece 113 is connected with the third connecting rod 120 through a first spherical hinge 125, and the second connecting piece 113 is connected with the fourth connecting rod 121 through a second spherical hinge 126; the first active lever 112 of the first branched chain 1 is connected with the first motor 110 through a first zero rotation pair 111, the first motor 110 is fixed on the frame 0, the second connecting member 113 of the first support chain 1 is connected with the movable platform 5 through a zero-two revolute pair 51, the axis of the first zero-two revolute pair 111 is perpendicular to the axis of the first revolute pair 114, the axis of the first zero-two revolute pair 111 is perpendicular to the axis of the second revolute pair 115, the axes of the first revolute pair 114, the second revolute pair 115, the third revolute pair 123 and the fourth revolute pair 124 are parallel to each other, the distance between the axes of the first revolute pair 114 and the second revolute pair 115 is equal to the distance between the center of the first spherical hinge 125 and the center of the second spherical hinge 126, and the distance between the center of the first spherical hinge 125 and the axis of the first revolute pair 114 is equal to the distance between the center of the second spherical hinge 126 and the axis of the second revolute pair 115.

The second branched chain 2 comprises a second driving rod 212, a fifth connecting rod 216, a sixth connecting rod 217, a seventh connecting rod 220, an eighth connecting rod 221, a third connecting piece 222 and a fourth connecting piece 213, the fifth connecting rod 216 is connected with the second driving rod 212 through a fifth revolute pair 214, the sixth connecting rod 217 is connected with the second driving rod 212 through a sixth revolute pair 215, the third connecting piece 222 is connected with the fifth connecting rod 216 through a seventh revolute pair 223, the third connecting piece 222 is connected with the sixth connecting rod 217 through an eighth revolute pair 224, the seventh connecting rod 220 is connected with the fifth connecting rod 216 through a third revolute pair 218, the eighth connecting rod 221 is connected with the sixth connecting rod 217 through a fourth revolute pair 219, the fourth connecting piece 213 is connected with the seventh connecting rod 220 through a third spherical hinge 225, and the fourth connecting piece 213 is connected with the eighth connecting rod 221 through a fourth spherical hinge 226; the second driving rod 212 of the second branched chain 2 is connected with the second motor 210 through the second zero-one revolute pair 211, the second motor 210 is fixed on the frame 0, the fourth connecting member 213 of the second branched chain 2 is connected with the movable platform 5 through a second zero-two revolute pair 52, the axis of the second zero-two revolute pair 211 is perpendicular to the axis of the fifth revolute pair 214, the axis of the second zero-two revolute pair 211 is perpendicular to the axis of the sixth revolute pair 215, the axes of the fifth revolute pair 214, the sixth revolute pair 215, the seventh revolute pair 223 and the eighth revolute pair 224 are parallel to each other, the distance between the axis of the fifth revolute pair 214 and the axis of the sixth revolute pair 215 is equal to the distance between the center of the third spherical hinge 225 and the center of the fourth spherical hinge 226, and the distance between the center of the third spherical hinge 225 and the axis of the fifth revolute pair 214 is equal to the distance between the center of the fourth spherical hinge 226 and the axis of the sixth revolute pair 215.

The third branched chain 3 includes a third driving rod 312, a ninth connecting rod 316, a tenth connecting rod 317, an eleventh connecting rod 320, a twelfth connecting rod 321, a fifth connecting rod 322, and a sixth connecting rod 313, the ninth connecting rod 316 is connected to the third driving rod 312 through a ninth revolute pair 314, the tenth connecting rod 317 is connected to the third driving rod 312 through a tenth revolute pair 315, the fifth connecting rod 322 is connected to the ninth connecting rod 316 through an eleventh revolute pair 323, the fifth connecting rod 322 is connected to the tenth connecting rod 317 through a twelfth revolute pair 324, the eleventh connecting rod 320 is connected to the ninth connecting rod 316 through a fifth revolute pair 318, the twelfth connecting rod 321 is connected to the tenth connecting rod 317 through a sixth revolute pair 319, the sixth connecting rod 313 is connected to the eleventh connecting rod 320 through a fifth spherical hinge 325, and the sixth connecting rod 313 is connected to the twelfth connecting rod 321 through a sixth spherical hinge 326; the third driving rod 312 of the third branched chain 3 is connected with the third motor 310 through a third zero-first rotating pair 311, the third motor 310 is fixed on the frame 0, the sixth connecting part 313 of the third branched chain 3 is connected with the movable platform 5 through a third zero-second rotating pair 53, the axis of the third zero rotating pair 311 is perpendicular to the axis of the ninth rotating pair 314, the axis of the third zero rotating pair 311 is perpendicular to the axis of the tenth rotating pair 315, the axes of the ninth rotating pair 314, the tenth rotating pair 315, the eleventh rotating pair 323 and the twelfth rotating pair 324 are parallel to each other, the distance between the axis of the ninth rotating pair 314 and the axis of the tenth rotating pair 315 is equal to the distance between the axis of the eleventh rotating pair 323 and the axis of the twelfth rotating pair 324, the distance between the axis of the ninth rotating pair 314 and the axis of the tenth rotating pair 315 is equal to the distance between the center of the fifth spherical hinge 325 and the center of the sixth spherical hinge 326, the distance between the center of the fifth spherical hinge 325 and the axis of the ninth rotating pair 314 is equal to the distance between the center of the sixth spherical hinge 315 .

The fourth branched chain 4 includes a fourth driving rod 412, a thirteenth connecting rod 416, a fourteenth connecting rod 417, a fifteenth connecting rod 420, a sixteenth connecting rod 421, a seventh connecting member 422, and an eighth connecting member 413, the thirteenth connecting rod 416 is connected to the fourth driving rod 412 through a thirteenth rotating pair 414, the fourteenth connecting rod 417 is connected to the fourth driving rod 412 through a fourteenth rotating pair 415, the seventh connecting member 422 is connected to the thirteenth connecting rod 416 through a fifteenth rotating pair 423, the seventh connecting member 422 is connected to the fourteenth connecting rod 417 through a sixteenth rotating pair 424, the fifteenth connecting rod 420 is connected to the thirteenth connecting rod 416 through a seventh moving pair 418, the sixteenth connecting rod 421 is connected to the fourteenth connecting rod 417 through an eighth moving pair 419, the eighth connecting member 413 is connected to the fifteenth connecting rod 420 through a seventh spherical hinge 425, and the eighth connecting member 413 is connected to the sixteenth connecting rod 421 through an eighth spherical hinge 426; the fourth driving rod 412 of the fourth branched chain 4 is connected with the fourth motor 410 through a fourth zero-first revolute pair 411, the fourth motor 410 is fixed on the frame 0, the eighth connecting piece 413 of the fourth branched chain 4 is connected with the movable platform 5 through a fourth zero-second revolute pair 54, the axis of the fourth zero revolute pair 411 is perpendicular to the axis of the thirteenth revolute pair 414, the axis of the fourth zero revolute pair 411 is perpendicular to the axis of the fourteenth revolute pair 415, the axes of the thirteenth revolute pair 414, the fourteenth revolute pair 415, the fifteenth revolute pair 423 and the sixteenth revolute pair 424 are parallel to each other, the distance between the axis of the thirteenth revolute pair 414 and the axis of the fourteenth revolute pair 415 is equal to the distance between the axis of the fifteenth revolute pair 423 and the axis of the sixteenth revolute pair 424, the distance between the axis of the thirteenth revolute pair 414 and the axis of the fourteenth revolute pair 415 is equal to the distance between the center of the seventh spherical hinge 425 and the center of the eighth spherical hinge 426, and the distance between the center of the thirteenth spherical hinge 425 and the thirteenth revolute pair 414 is equal to the center of the fourteenth spherical hinge 426 The distance between the axes of the kinematic pairs 415 is equal.

The first motor 110 drives the first driving rod 112 of the first branched chain 1 to move, the second motor 210 drives the second driving rod 212 of the second branched chain 2 to move, the third motor 310 drives the third driving rod 312 of the third branched chain 3 to move, and the fourth motor 410 drives the fourth driving rod 412 of the fourth branched chain 4 to move, so that spatial three-dimensional translation and one-dimensional rotation of the movable platform 5 can be realized.

The above embodiments are merely illustrative of the technical ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the protection scope of the present invention. All changes, modifications, substitutions, combinations or simplifications made according to the spirit and principle of the technical scheme of the invention are equivalent substitution modes, and the invention is within the protection scope of the invention as long as the invention aims at the invention and the technical principle and the invention concept of the four-freedom-degree parallel robot containing the variable-rod-length parallelogram closed-loop subchain do not depart from the invention.

Claims (1)

1. Four-degree-of-freedom parallel robot containing variable-rod-length parallelogram closed-loop subchain comprises a rack 0, a first branched chain 1, a second branched chain 2, a third branched chain 3, a fourth branched chain 4, a first motor 110, a second motor 210, a third motor 310, a fourth motor 410 and a movable platform 5, and is characterized in that:

the first support chain 1 comprises a first driving rod 112, a first connecting rod 116, a second connecting rod 117, a third connecting rod 120, a fourth connecting rod 121, a first connecting piece 122 and a second connecting piece 113, wherein the first connecting rod 116 is connected with the first driving rod 112 through a first revolute pair 114, the second connecting rod 117 is connected with the first driving rod 112 through a second revolute pair 115, the first connecting piece 122 is connected with the first connecting rod 116 through a third revolute pair 123, the first connecting piece 122 is connected with the second connecting rod 117 through a fourth revolute pair 124, the third connecting rod 120 is connected with the first connecting rod 116 through a first revolute pair 118, the fourth connecting rod 121 is connected with the second connecting rod 117 through a second revolute pair 119, the second connecting piece 113 is connected with the third connecting rod 120 through a first spherical hinge 125, and the second connecting piece 113 is connected with the fourth connecting rod 121 through a second spherical hinge 126; the first active lever 112 of the first branched chain 1 is connected with the first motor 110 through a first zero rotation pair 111, the first motor 110 is fixed on the frame 0, the second connecting member 113 of the first support chain 1 is connected with the movable platform 5 through a zero-two revolute pair 51, the axis of the first zero-two revolute pair 111 is perpendicular to the axis of the first revolute pair 114, the axis of the first zero-two revolute pair 111 is perpendicular to the axis of the second revolute pair 115, the axes of the first revolute pair 114, the second revolute pair 115, the third revolute pair 123 and the fourth revolute pair 124 are parallel to each other, the distance between the axes of the first revolute pair 114 and the second revolute pair 115 is equal to the distance between the center of the first spherical hinge 125 and the center of the second spherical hinge 126, and the distance between the center of the first spherical hinge 125 and the axis of the first revolute pair 114 is equal to the distance between the center of the second spherical hinge 126 and the axis of the second revolute pair 115;

the second branched chain 2 comprises a second driving rod 212, a fifth connecting rod 216, a sixth connecting rod 217, a seventh connecting rod 220, an eighth connecting rod 221, a third connecting piece 222 and a fourth connecting piece 213, the fifth connecting rod 216 is connected with the second driving rod 212 through a fifth revolute pair 214, the sixth connecting rod 217 is connected with the second driving rod 212 through a sixth revolute pair 215, the third connecting piece 222 is connected with the fifth connecting rod 216 through a seventh revolute pair 223, the third connecting piece 222 is connected with the sixth connecting rod 217 through an eighth revolute pair 224, the seventh connecting rod 220 is connected with the fifth connecting rod 216 through a third revolute pair 218, the eighth connecting rod 221 is connected with the sixth connecting rod 217 through a fourth revolute pair 219, the fourth connecting piece 213 is connected with the seventh connecting rod 220 through a third spherical hinge 225, and the fourth connecting piece 213 is connected with the eighth connecting rod 221 through a fourth spherical hinge 226; the second driving rod 212 of the second branched chain 2 is connected with the second motor 210 through the second zero-one revolute pair 211, the second motor 210 is fixed on the frame 0, the fourth connecting member 213 of the second branched chain 2 is connected with the movable platform 5 through two zero two revolute pairs 52, the axis of the second zero one revolute pair 211 is perpendicular to the axis of the fifth revolute pair 214, the axis of the second zero one revolute pair 211 is perpendicular to the axis of the sixth revolute pair 215, the axes of the fifth revolute pair 214, the sixth revolute pair 215, the seventh revolute pair 223 and the eighth revolute pair 224 are parallel to each other, the distance between the axis of the fifth revolute pair 214 and the axis of the sixth revolute pair 215 is equal to the distance between the axis of the seventh revolute pair 223 and the axis of the eighth revolute pair 224, the distance between the axis of the fifth revolute pair 214 and the axis of the sixth revolute pair 215 is equal to the distance between the center of the third spherical hinge 225 and the center of the fourth spherical hinge 226, and the distance between the center of the third spherical hinge 225 and the axis of the fifth revolute pair 214 are equal to the distance between the center of the fourth spherical hinge 226 and the axis of the sixth revolute pair 215;

the third branched chain 3 includes a third driving rod 312, a ninth connecting rod 316, a tenth connecting rod 317, an eleventh connecting rod 320, a twelfth connecting rod 321, a fifth connecting rod 322, and a sixth connecting rod 313, the ninth connecting rod 316 is connected to the third driving rod 312 through a ninth revolute pair 314, the tenth connecting rod 317 is connected to the third driving rod 312 through a tenth revolute pair 315, the fifth connecting rod 322 is connected to the ninth connecting rod 316 through an eleventh revolute pair 323, the fifth connecting rod 322 is connected to the tenth connecting rod 317 through a twelfth revolute pair 324, the eleventh connecting rod 320 is connected to the ninth connecting rod 316 through a fifth revolute pair 318, the twelfth connecting rod 321 is connected to the tenth connecting rod 317 through a sixth revolute pair 319, the sixth connecting rod 313 is connected to the eleventh connecting rod 320 through a fifth spherical hinge 325, and the sixth connecting rod 313 is connected to the twelfth connecting rod 321 through a sixth spherical hinge 326; the third driving rod 312 of the third branched chain 3 is connected with the third motor 310 through a third zero-first rotating pair 311, the third motor 310 is fixed on the frame 0, the sixth connecting part 313 of the third branched chain 3 is connected with the movable platform 5 through a third zero-second rotating pair 53, the axis of the third zero rotating pair 311 is perpendicular to the axis of the ninth rotating pair 314, the axis of the third zero rotating pair 311 is perpendicular to the axis of the tenth rotating pair 315, the axes of the ninth rotating pair 314, the tenth rotating pair 315, the eleventh rotating pair 323 and the twelfth rotating pair 324 are parallel to each other, the distance between the axis of the ninth rotating pair 314 and the axis of the tenth rotating pair 315 is equal to the distance between the axis of the eleventh rotating pair 323 and the axis of the twelfth rotating pair 324, the distance between the axis of the ninth rotating pair 314 and the axis of the tenth rotating pair 315 is equal to the distance between the center of the fifth spherical hinge 325 and the center of the sixth spherical hinge 326, the distance between the center of the fifth spherical hinge 325 and the axis of the ninth rotating pair 314 is equal to the distance between the center of the sixth spherical hinge 315 (ii) a

The fourth branched chain 4 includes a fourth driving rod 412, a thirteenth connecting rod 416, a fourteenth connecting rod 417, a fifteenth connecting rod 420, a sixteenth connecting rod 421, a seventh connecting member 422, and an eighth connecting member 413, the thirteenth connecting rod 416 is connected to the fourth driving rod 412 through a thirteenth rotating pair 414, the fourteenth connecting rod 417 is connected to the fourth driving rod 412 through a fourteenth rotating pair 415, the seventh connecting member 422 is connected to the thirteenth connecting rod 416 through a fifteenth rotating pair 423, the seventh connecting member 422 is connected to the fourteenth connecting rod 417 through a sixteenth rotating pair 424, the fifteenth connecting rod 420 is connected to the thirteenth connecting rod 416 through a seventh moving pair 418, the sixteenth connecting rod 421 is connected to the fourteenth connecting rod 417 through an eighth moving pair 419, the eighth connecting member 413 is connected to the fifteenth connecting rod 420 through a seventh spherical hinge 425, and the eighth connecting member 413 is connected to the sixteenth connecting rod 421 through an eighth spherical hinge 426; the fourth driving rod 412 of the fourth branched chain 4 is connected with the fourth motor 410 through a fourth zero-first revolute pair 411, the fourth motor 410 is fixed on the frame 0, the eighth connecting piece 413 of the fourth branched chain 4 is connected with the movable platform 5 through a fourth zero-second revolute pair 54, the axis of the fourth zero revolute pair 411 is perpendicular to the axis of the thirteenth revolute pair 414, the axis of the fourth zero revolute pair 411 is perpendicular to the axis of the fourteenth revolute pair 415, the axes of the thirteenth revolute pair 414, the fourteenth revolute pair 415, the fifteenth revolute pair 423 and the sixteenth revolute pair 424 are parallel to each other, the distance between the axis of the thirteenth revolute pair 414 and the axis of the fourteenth revolute pair 415 is equal to the distance between the axis of the fifteenth revolute pair 423 and the axis of the sixteenth revolute pair 424, the distance between the axis of the thirteenth revolute pair 414 and the axis of the fourteenth revolute pair 415 is equal to the distance between the center of the seventh spherical hinge 425 and the center of the eighth spherical hinge 426, and the distance between the center of the thirteenth spherical hinge 425 and the thirteenth revolute pair 414 is equal to the center of the fourteenth spherical hinge 426 The distance between the axes of the kinematic pairs 415 is equal.

Images