A novel nine-degree-of-freedom motion redundant parallel mechanism

Abstract

The application provides a novel nine-degree-of-freedom motion redundant parallel mechanism, which comprises a fixed base platform, a movable end platform and three motion branches; wherein the fixed base platform and the movable end platform are oppositely arranged and connected through the three motion branches; each of the motion branches is a hybrid structure, which is sequentially connected by a first serial part, a parallel part and a second serial part, and has seven degrees of freedom in space. The application has compact structure, high structural stiffness, small rotational inertia of the motion branch, low motion transmission cumulative error and high end positioning accuracy; meanwhile, the application has three redundant degrees of freedom, and the configuration of each motion branch can be changed without changing the position and posture of the movable end platform, so that the application can actively avoid singular and other undesirable configurations, and the movable end platform has more flexible motion, and the mechanism has larger working space and stronger posture adjustment capacity.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of mechanism and robot technology, in particular to a novel nine-degree-of-freedom motion-redundant parallel mechanism. BACKGROUND

[0002] Compared with serial mechanisms, parallel mechanisms have more compact structure, faster response speed and better load capacity, so they are widely used in the fields of automated production and motion simulator. At the same time, the structural stiffness and positioning accuracy of parallel mechanisms are also significantly improved, so they also have an important position in the field of precision instrument manufacturing and assembly.

[0003] However, due to the influence of singular configurations, the workspaces of most parallel mechanisms are very limited, especially in the attitude space. This greatly limits the application range of traditional parallel mechanisms in the field of manufacturing and assembly. Specifically, without changing the structure, size and installation method of the mechanism, most traditional parallel mechanisms are only suitable for the manufacturing and assembly of one or several specific and simple-shaped parts, and are not suitable for the manufacturing and assembly of parts with complex structure or multiple surfaces to be processed, and cannot be adaptively applied to the manufacturing and assembly of multiple parts.

[0004] Compared with traditional parallel mechanisms, the motion branch of the motion-redundant parallel mechanism has more degrees of freedom than the end-effector, which can change the configuration of the motion branch and the mechanism while keeping the position and attitude of the end-effector unchanged. This makes the motion-redundant parallel mechanism actively avoid undesirable configurations, including singular configurations, thereby obtaining more flexible motion and larger workspace.

[0005] In current research, the motion branch of most parallel mechanisms is designed based on serial structure. However, for the long motion branch of the motion-redundant parallel mechanism, this will greatly increase the cumulative error in the motion transmission process, thereby reducing the positioning accuracy of the end-effector. Therefore, the motion branch of the motion-redundant parallel mechanism is designed based on hybrid structure, which has good comprehensive performance. While retaining the motion flexibility of serial structure, it also has the structural compactness and high precision of parallel structure, which can reduce the influence of cumulative error on the positioning accuracy of the end-effector. SUMMARY

[0006] Based on the problems existing in the prior art, the purpose of the present application is to provide a novel nine-degree-of-freedom motion-redundant parallel mechanism which can actively avoid undesirable configurations, has a large workspace and strong attitude adjustment capability, and has strong adaptive ability in the field of manufacturing and assembly.

[0007] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0008] A novel nine-degree-of-freedom motion redundant parallel mechanism, comprising a rack fixed platform, a terminal moving platform and three motion branch chains;

[0009] The terminal moving platform is oppositely arranged with the rack fixed platform, and the two are connected with each other through the three motion branch chains.

[0010] The three motion branch chains are of the same structure, and each of the three motion branch chains has seven degrees of freedom, and the two ends are connected with the rack fixed platform and the terminal moving platform respectively.

[0011] According to an embodiment of the present application, the rack fixed platform comprises a fixed platform body and three fixed driver supports, and the fixed driver supports are distributed along the circumference of the fixed platform body and are fixedly connected with the fixed platform body.

[0012] Each of the three motion branch chains comprises a first serial part, a parallel part and a second serial part.

[0013] The first serial part has one degree of freedom, and comprises a first rotary driver and a branch driver support.

[0014] The first rotary driver is arranged on the fixed driver support of the rack fixed platform, and an output shaft is fixedly connected with the branch driver support.

[0015] The parallel part has two degrees of freedom, and a rack end is arranged on the branch driver support of the first serial part, and an output end is connected with the second serial part.

[0016] The second serial part has four degrees of freedom, and is a driven part, comprising three rotary hinges and a redundant link. The three rotary hinges provide three rotary degrees of freedom. Two ends of the redundant link are connected with the three rotary hinges and the terminal moving platform respectively, and the redundant link provides one rotary degree of freedom, which is the redundant degree of freedom of the motion branch chain.

[0017] According to an embodiment of the present application, the parallel part comprises a second rotary driver, a third rotary driver, a first crank link, a second crank link, a first triangular link, a second triangular link, a driven link, an output link, a link shaft pad and a link rotary connection assembly.

[0018] The second rotary driver and the third rotary driver are arranged on the two sides of the branch driver support of the first serial part respectively, and output shafts of the second rotary driver and the third rotary driver are fixedly connected with crank ends of the first crank link and the second crank link respectively.

[0019] The first triangular link is rotatably connected with the link end of the second crank link, one vertex of the second triangular link and one end of the driven link at three vertices respectively.

[0020] The second triangular link is rotatably connected with the link end of the first crank link and the middle part of the output link at the other two vertices not connected with the first triangular link;

[0021] One end of the output link is rotatably connected with the driven link, and the other end is fixedly connected with the second serial part;

[0022] The link rotatable connection assembly comprises a link rotation shaft, a link bearing and a link bearing pressing plate; the rotatable connections among the first crank link, the second crank link, the first triangular link, the second triangular link, the driven link and the output link are realized through the link rotatable connection assembly; and the link rotation shaft pad is used to fill the height difference caused by the thickness of the link.

[0023] According to an embodiment of the present application, the three rotatable hinges of the second serial part are spherical hinges, comprising a spherical head and a spherical seat; the spherical head is fixedly connected with the redundant link, and the spherical seat is fixedly connected with the output link of the parallel part.

[0024] According to an embodiment of the present application, the three rotatable hinges of the second serial part are composite hinges, comprising a link base, a first rotatable base, a second rotatable base and a third rotatable base;

[0025] The link base, the first rotatable base, the second rotatable base and the third rotatable base are rotatably connected in sequence;

[0026] The link base is fixedly connected with the output link of the parallel part;

[0027] The flange end of the third rotatable base is fixedly connected with the redundant link, and the link end is rotatably connected with the second rotatable base.

[0028] According to an embodiment of the present application, the link base comprises two completely same link base side plates, two completely same output link pads, a hinge first bearing, a first bearing base and a first bearing end cover;

[0029] The two output link pads are fixedly connected to the two sides of the output link of the parallel part, and one link base side plate is fixedly connected to the outer side of each of the two output link pads;

[0030] The first bearing base is arranged at one end of the link base away from the output link of the parallel part, and is fixedly connected with the two link base side plates on the two sides; the first bearing base is provided with a mounting hole for mounting the hinge first bearing, and the hinge first bearing is fixedly connected with the first bearing base at the mounting hole through the outer ring thereof; the first bearing end cover is fixedly connected with the first bearing base, and clamps and fixes the two sides of the outer ring of the hinge first bearing; the inner ring of the hinge first bearing is fixedly connected with the first rotatable base.

[0031] According to an embodiment of the present application, the first rotatable base comprises a hinge first rotation shaft, a second bearing base, a hinge second bearing and a second bearing end cover;

[0032] The hinge first rotating shaft end is rotatably connected with the connecting rod base through the hinge first bearing, and the flange end is fixedly connected with the second bearing base; the second bearing base is provided with a mounting hole for mounting the hinge second bearing, and the hinge second bearing is fixedly connected with the second bearing base through the outer ring at the mounting hole; the second bearing base is fixedly connected with the second bearing end cover, and the two sides of the outer ring of the hinge second bearing are clamped and fixed; the inner ring of the hinge second bearing is fixedly connected with the second rotating base.

[0033] According to an embodiment of the present application, the second rotating base comprises two identical second base side plates, a hinge second rotating shaft, a hinge rotating shaft gasket, a third bearing base, a hinge third bearing and a third bearing end cover.

[0034] The flange end of the hinge second rotating shaft is fixedly connected with one of the second base side plates, and the rotating shaft end is rotatably connected with the first rotating base through the hinge second bearing; the hinge rotating shaft gasket is arranged on the hinge second rotating shaft to fill the height difference between the hinge second bearing and the second base side plate on the side of the rotating shaft end of the hinge second rotating shaft; the third bearing base is arranged at the end of the second rotating base away from the first rotating base, and the two sides thereof are fixedly connected with the two second base side plates, respectively; the third bearing base is provided with a mounting hole for mounting the hinge third bearing, and the hinge third bearing is fixedly connected with the third bearing base through the outer ring at the mounting hole; the third bearing base is fixedly connected with the third bearing end cover, and the two sides of the outer ring of the hinge third bearing are clamped and fixed; the inner ring of the hinge third bearing is fixedly connected with the connecting rod end of the third rotating base.

[0035] According to an embodiment of the present application, the redundant connecting rod comprises a redundant connecting rod rotating shaft and a redundant connecting rod main body; the two ends of the redundant connecting rod main body are fixedly connected with the three rotating hinges of the second series connection part and the flange end of the redundant connecting rod rotating shaft, respectively; the rotating shaft end of the redundant connecting rod rotating shaft is rotatably connected with the end moving platform.

[0036] According to an embodiment of the present application, the end moving platform comprises a moving platform main body, three identical moving platform bearing pressing plates and three identical moving platform bearings.

[0037] The moving platform bearing pressing plates are circumferentially distributed and fixedly connected with the moving platform main body;

[0038] The moving platform main body is provided with mounting holes, and the outer rings of the moving platform bearings are fixedly connected with the moving platform main body at the corresponding mounting holes; the moving platform main body and the moving platform bearing pressing plates jointly clamp and fix the two sides of the outer rings of the moving platform bearings;

[0039] The inner rings of the moving platform bearings are fixedly connected with the rotating shaft end of the redundant connecting rod rotating shaft.

[0040] In general, the present application has the following advantages:

[0041] 1. The application provides a novel nine-degree-of-freedom motion redundant parallel mechanism, wherein the motion branch chain is based on a hybrid structure design, the structure is compact and has high structural stiffness, and the cumulative error of motion transmission can be reduced; meanwhile, the hybrid motion branch chain can enable the drivers to be centrally arranged at one end of the fixed platform of the rack, the rotational inertia of the motion branch chain during the motion process can be greatly reduced, and thus good dynamic performance is obtained.

[0042] 2. The application provides a novel nine-degree-of-freedom motion redundant parallel mechanism, wherein the redundant connecting rod of the second series connection part of the motion branch chain can provide a redundant rotational degree of freedom, each motion branch chain can independently transform its own configuration without affecting the position and posture of the end moving platform, and the novel nine-degree-of-freedom motion redundant parallel mechanism can actively avoid singular configurations and other undesirable configurations during the motion process, the motion of the motion branch chain is more flexible, and thus the novel nine-degree-of-freedom motion redundant parallel mechanism can have a larger working space and stronger posture adjustment capacity.

[0043] 3. The application provides a novel nine-degree-of-freedom motion redundant parallel mechanism, wherein the parallel part of the motion branch chain can amplify the input angular displacement of the second rotational driver and the third rotational driver through the redundant degree of freedom of the motion branch chain, and the response speed of the novel nine-degree-of-freedom motion redundant parallel mechanism can be further improved.

[0044] 4. The application provides a novel nine-degree-of-freedom motion redundant parallel mechanism, wherein the three rotational hinges included in the novel nine-degree-of-freedom motion redundant parallel mechanism can be converted from a spherical hinge mode to a composite hinge mode; the composite hinge mode can greatly reduce the influence of the motion pair stroke limit on the working space of the motion branch chain, and the flexibility of the motion of each motion branch chain can be significantly improved, and thus the posture adjustment capacity of the end moving platform of the novel nine-degree-of-freedom motion redundant parallel mechanism is further improved. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 FIG. 1 is a schematic diagram of the overall structure of a novel nine-degree-of-freedom motion redundant parallel mechanism provided by the application, wherein the three rotational hinges of the second series connection part adopt a spherical hinge mode;

[0046] Figure 2 FIG. 2 is a schematic diagram of the overall structure of a novel nine-degree-of-freedom motion redundant parallel mechanism provided by the application, wherein the three rotational hinges of the second series connection part adopt a composite hinge mode;

[0047] FIG. 3(a) is a schematic diagram of the structure of a motion branch chain in the embodiment of the application, wherein the three rotational hinges of the second series connection part adopt a composite hinge mode;

[0048] Figure 3(b) is an exploded structural schematic diagram of the connecting rod rotation connection assembly in the embodiment of the present application;

[0049] Figure 4(a) is a structural schematic diagram of the connecting rod base of the compound hinge in the embodiment of the present application;

[0050] Figure 4(b) is an exploded structural schematic diagram of the connecting rod base of the compound hinge in the embodiment of the present application;

[0051] Figure 5(a) is a structural schematic diagram of the first rotation base of the compound hinge in the embodiment of the present application;

[0052] Figure 5(b) is an exploded structural schematic diagram of the first rotation base of the compound hinge in the embodiment of the present application;

[0053] Figure 6(a) is an assembly structural schematic diagram of the second rotation base and the third rotation base of the compound hinge in the embodiment of the present application;

[0054] Figure 6(b) is an exploded structural schematic diagram of the second rotation base and the third rotation base of the compound hinge in the embodiment of the present application;

[0055] Figure 7(a) is a structural schematic diagram of the redundant connecting rod in the embodiment of the present application;

[0056] Figure 7(b) is an exploded structural schematic diagram of the redundant connecting rod in the embodiment of the present application;

[0057] Figure 8 Figure 8 is a structural schematic diagram of the end moving platform in the embodiment of the present application.

[0058] In the figures:

[0059] 1: fixed platform; 1-1: fixed platform body; 1-2: fixed driver support;

[0060] 2: end moving platform; 2-1: moving platform body; 2-2: moving platform bearing; 2-3: moving platform bearing pressing plate;

[0061] 3: motion branch chain;

[0062] 3-1: first series part; 31-1: first rotation driver; 31-2: branch chain driver support;

[0063] 3-2: parallel part; 32-1: second rotation driver; 32-2: third rotation driver; 32-3: first crank connecting rod; 32-4: second crank connecting rod; 32-5: first triangular connecting rod; 32-6: second triangular connecting rod; 32-7: driven connecting rod; 32-8: output connecting rod; 32-9: connecting rod rotation shaft pad; 32-10: connecting rod rotation connection assembly;

[0064] 3210-1: Connecting rod shaft; 3210-2: Connecting rod bearing; 3210-3: Connecting rod bearing pressure plate;

[0065] 3-3: Second series connection section;

[0066] 33-1: Ball joint; 331-1: Ball head; 331-2: Ball seat;

[0067] 33-2: Redundant connecting rod; 332-1: Redundant connecting rod pivot; 332-2: Redundant connecting rod body;

[0068] 33-3: Composite hinge;

[0069] 333-1: Connecting rod base; 3331-1: Connecting rod base side plate; 3331-2: Output connecting rod pad; 3331-3: First hinge bearing; 3331-4: First bearing base; 3331-5: First bearing end cap;

[0070] 333-2: First rotating base; 3332-1: First hinge shaft; 3332-2: Second bearing base; 3332-3: Second hinge bearing; 3332-4: Second bearing end cap;

[0071] 333-3: Second rotating base; 3333-1: Second base side plate; 3333-2: Second hinge pivot; 3333-3: Hinge pivot washer; 3333-4: Third bearing base; 3333-5: Third hinge bearing; 3333-6: Third bearing end cap;

[0072] 333-4: Third rotating base. Detailed Implementation

[0073] The following descriptions of the embodiments are made with reference to the accompanying illustrations to illustrate specific embodiments in which the invention can be implemented.

[0074] like Figure 1 and Figure 2 As shown, a novel nine-DOF motion redundant parallel mechanism includes a frame fixed platform 1, an end effector moving platform 2, and three motion chains 3. The frame fixed platform 1 consists of a fixed platform body 1-1 and three structurally identical fixed actuator supports 1-2. The fixed platform body 1-1 is configured as an equilateral triangular plate; the fixed actuator supports 1-2 are distributed circumferentially along the fixed platform body 1-1, located on the center line of the equilateral triangle, spaced at 120-degree intervals, and fixedly connected to the fixed platform body 1-1 by screws. The end effector moving platform 2 is positioned opposite the frame fixed platform 1, and the two are interconnected by the three motion chains 3. The three motion chains 3 have identical structures and dimensions; each motion chain 3 has one end fixedly connected to a fixed actuator support 1-2, and the other end rotatably connected to the end effector moving platform 2.

[0075] As Figure 2 Each of the kinematic chains 3 is a hybrid structure, as shown in FIG. 3(a) and FIG. 3(b), which is composed of a first series part 3-1, a parallel part 3-2 and a second series part 3-3, and has seven degrees of freedom in three-dimensional space, including three degrees of freedom of movement in three orthogonal directions, three degrees of freedom of rotation in three orthogonal directions and one redundant degree of freedom of rotation.

[0076] As a specific embodiment, the first series part 3-1 includes a first rotary driver 31-1 and a chain driver support 31-2, and has one degree of freedom. The outside of the first rotary driver 31-1 is fixedly connected to the fixed driver support 1-2 by a screw, and the output shaft of the first rotary driver 31-1 is fixedly connected to the chain driver support 31-2 by a screw. The output shafts of the first rotary drivers 31-1 of the three kinematic chains 3 are coplanar and converge at a point, and the plane is parallel to the plane on which the fixed platform body 1-1 is located. This structural layout can avoid a type of singular configuration of the kinematic chain 3 and ensure the continuity of the working space.

[0077] The parallel part 3-2 is a planar parallel structure and has two degrees of freedom in the plane. The parallel part 3-2 includes a second rotary driver 32-1, a third rotary driver 32-2, a first crank link 32-3, a second crank link 32-4, a first triangular link 32-5, a second triangular link 32-6, a driven link 32-7, an output link 32-8, a link shaft pad 32-9 and a link rotary connection assembly 32-10.

[0078] The outer parts of the second rotation driver 32-1 and the third rotation driver 32-2 are respectively fixed to the two sides of the branch driver support 31-2 by screws, and the output shafts are respectively connected to the crank ends of the first crank link 32-3 and the second crank link 32-4 and fixed by screws. The axes of the output shafts of the second rotation driver 32-1 and the third rotation driver 32-2 coincide with each other, and are perpendicular to the axis of the output shaft of the first rotation driver 31-1 in the motion branch 3 and meet at a point. The end of the first crank link 32-3 away from the driver (i.e. the link end) is rotationally connected to the second triangular link 32-6 at one of the vertices of the second triangular link 32-6; the end of the second crank link 32-4 away from the driver (i.e. the link end) is rotationally connected to the first triangular link 32-5 at one of the vertices of the first triangular link 32-5. The first triangular link 32-5 and the second triangular link 32-6 are both provided as equilateral triangular plate-shaped links, and are arranged in a posture with the opposite vertices being rotationally connected, and only connected to each other at the opposite vertices without being connected to other links. The first triangular link 32-5 is also rotationally connected to the driven link 32-7 at the last vertex of the first triangular link 32-5 which is not connected to other links; the second triangular link 32-6 is also rotationally connected to the middle part of the output link 32-8 at the last vertex of the second triangular link 32-6 which is not connected to other links. One end of the output link 32-8 is rotationally connected to the end of the driven link 32-7 away from the first triangular link 32-5, and the other end is fixed to the second series part 3-3.

[0079] As a specific embodiment, the rotational connections between the first crank link 32-3, the second crank link 32-4, the first triangular link 32-5, the second triangular link 32-6, the driven link 32-7 and the output link 32-8 are all realized by the link rotational connection assembly 32-10. The link rotational connection assembly 32-10 comprises a link rotational shaft 3210-1, a link bearing 3210-2 and a link bearing pressing plate 3210-3. Take the rotational connection between the first triangular link 32-5 and the driven link 32-7 as an example to illustrate the specific implementation of the link rotational connection assembly 32-10: the first triangular link 32-5 is provided with a mounting hole at the corresponding vertex, the link bearing 3210-2 is arranged in the mounting hole, and the outer ring of the link bearing 3210-2 is fixedly connected with the first triangular link 32-5 through the mounting hole; the link bearing pressing plate 3210-3 is arranged on the mounting hole, and the link bearing pressing plate 3210-3 is fixedly connected with the first triangular link 32-5 by screws, clamping and fixing the two sides of the outer ring of the link bearing 3210-2; the two sides of the inner ring of the link bearing 3210-2 are clamped and fixed by the rotational shaft step of the link rotational shaft 3210-1 and the nut; the link rotational shaft 3210-1 is connected with the inner ring of the link bearing 3210-2 at the rotational shaft end, and is fixedly connected with the driven link 32-7 at the flange end by screws; the link bearing 3210-2 is specifically arranged as a pair of opposed angular contact bearings to improve the accuracy. When this rotational connection mode is adopted, due to the superposition of the thicknesses of the link members, there is a height difference at the rotational connection between the first crank link 32-3 and the second triangular link 32-6, and the height difference is filled by the link rotational shaft pad 32-9, which is arranged between the flange end of the link rotational shaft 3210-1 and the second triangular link 32-6 and is fixedly connected with them by screws.

[0080] The second series part 3-3 comprises a three-rotational hinge and a redundant link 33-2, and has four degrees of freedom. The three-rotational hinge has three rotational degrees of freedom, and the directions are mutually orthogonal.

[0081] As shown in FIGS. 7(a) and 7(b), the redundant link 33-2 is composed of a redundant link rotational shaft 332-1 and a redundant link body 332-2. The redundant link body 332-2 is arranged as an L-shaped link, one end of which is fixedly connected with the three-rotational hinge, and the other end is fixedly connected with the flange end of the redundant link rotational shaft 332-1 by screws. The redundant link rotational shaft 332-1 is rotationally connected with the terminal moving platform 2 at the rotational shaft end, and the rotational axis direction is perpendicular to the plane where the terminal moving platform 2 is located, thereby providing a rotational degree of freedom for the second series part 3-3. This degree of freedom is the redundant degree of freedom of the motion branch 3.

[0082] As Figure 8As shown, the end moving platform 2 includes a moving platform body 2-1, three identical moving platform bearings 2-2, and three identical moving platform bearing pressure plates 2-3. The moving platform bearings 2-2 are distributed circumferentially along the moving platform body 2-1 at 120-degree intervals. The outer ring is fixedly connected to the corresponding mounting holes provided on the moving platform body 2-1, and the inner ring is connected to the shaft end of the redundant connecting rod shaft 332-1. The two sides of the inner ring are clamped and fixed by the shaft step and nut of the redundant connecting rod shaft 332-1, respectively. The moving platform bearing pressure plates 2-3 are fixedly connected to the moving platform body 2-1 by screws, and the two clamp and fix the outer ring of the moving platform bearings 2-2.

[0083] like Figure 1 As shown, the three-rotation hinge of the second series section 3-3 can be configured as a ball hinge 33-1. The ball hinge 33-1 includes a ball head 331-1 and a ball seat 331-2. The ball head 331-1 is fixedly connected to the redundant connecting rod 33-2, while the ball seat 331-2 is fixedly connected to the output connecting rod 32-8 of the parallel section 3-2. This configuration is compact, has a low moment of inertia, and its force analysis is simple.

[0084] like Figure 2 As shown in Figures 3(a) and 3(b), the three-rotation hinge of the second series part 3-3 can also be configured as a composite hinge 33-3. The composite hinge 33-3 is composed of a connecting rod base 333-1, a first rotating base 333-2, a second rotating base 333-3, and a third rotating base 333-4 connected in sequence. The composite hinge 33-3 is fixed to the parallel part 3-2 at the connecting rod base 333-1 and fixed to the redundant connecting rod 33-2 at the third rotating base 333-4. With this configuration, the three-rotation hinge can have a larger rotation range in each degree of freedom direction, which can reduce the restriction of the kinematic pair stroke on the working space of the kinematic branch 3, making the movement of the kinematic branch 3 more flexible, and thus enabling the end effector platform 2 to have a larger working space and stronger attitude adjustment capability.

[0085] Furthermore, as shown in Figures 4(a) and 4(b), the connecting rod base 333-1 includes two identical connecting rod base side plates 3331-1, two identical output connecting rod pads 3331-2, a hinge first bearing 3331-3, a first bearing base 3331-4, and a first bearing end cap 3331-5; the first bearing base 3331-4 is provided with a mounting hole for mounting the hinge first bearing 3331-3, which is fixedly connected to the outer ring of the hinge first bearing 3331-3 at the mounting hole; the first bearing base 3331-4 is provided with a first bearing end cap 3331-5, and the two are fixedly connected by screws, and together clamp and fix the two sides of the outer ring of the hinge first bearing 3331-3. Two connecting rod base side plates 3331-1 are respectively connected to both sides of the first bearing base 3331-4 and fixed with screws; both connecting rod base side plates 3331-1 are connected to the output connecting rod 32-8 of the parallel part 3-2 at the end away from the first bearing base 3331-4, and the height difference caused by the size of the first bearing base 3331-4 is made up by the output connecting rod pad 3331-2; the connecting rod base side plates 3331-1, the output connecting rod pad 3331-2 and the output connecting rod 32-8 are finally clamped and fixed with bolts and nuts.

[0086] As shown in Figures 5(a) and 5(b), the first rotating base 333-2 includes a first hinge shaft 3332-1, a second bearing base 3332-2, a second hinge bearing 3332-3, and a second bearing end cap 3332-4. The shaft end of the first hinge shaft 3332-1 is connected to the inner ring of the first hinge bearing 3331-3. The two sides of the inner ring of the first hinge bearing 3331-3 are clamped and fixed by the shaft step of the first hinge shaft 3332-1 and the nut, respectively. The flange end of the first hinge shaft 3332-1 is fixed to the second bearing base 3332-2 by screws. The second bearing base 3332-2 is provided with a mounting hole for mounting the hinge second bearing 3332-3, which is fixedly connected to the outer ring of the hinge second bearing 3332-3 at the mounting hole; a second bearing end cap 3332-4 is provided on the second bearing base 3332-2, and the two are fixedly connected by screws, and respectively clamp and fix the two sides of the outer ring of the hinge second bearing 3332-3.

[0087] As shown in FIG. 6(a) and FIG. 6(b), the second rotating base 333-3 comprises two identical second base side plates 3333-1, a hinged second rotating shaft 3333-2, a hinged rotating shaft washer 3333-3, a third bearing base 3333-4, a hinged third bearing 3333-5 and a third bearing end cover 3333-6. The hinged second rotating shaft 3333-2 is fixed to one second base side plate 3333-1 at the flange end by a screw, fixed to the inner ring of the hinged second bearing 3332-3 at the rotating shaft end, and clamps the inner ring of the hinged second bearing 3332-3 on both sides through the rotating shaft step and the hinged rotating shaft washer 3333-3; the hinged rotating shaft washer 3333-3 is finally clamped by the other second base side plate 3333-1 and fixed by a nut. Both second base side plates 3333-1 are connected to the third bearing base 3333-4 at the end away from the hinged second rotating shaft 3333-2 and fixed by a screw. The third bearing base 3333-4 is provided with a mounting hole, and the outer ring of the hinged third bearing 3333-5 is fixed at the mounting hole; the third bearing end cover 3333-6 is arranged on the third bearing base 3333-4, and the two are fixed by a screw and clamp the outer ring of the hinged third bearing 3333-5 on both sides, respectively. The inner ring of the hinged third bearing 3333-5 is fixed to the rotating shaft end of the third rotating base 333-4, and the two sides of the inner ring are clamped and fixed by the rotating shaft step and the nut of the third rotating base 333-4, respectively; the flange end of the third rotating base 333-4 is fixed to the redundant connecting rod 33-2 by a screw.

[0088] The hinged first bearing 3331-3, the hinged second bearing 3332-3 and the hinged third bearing 3333-5 are all arranged as opposed angular contact bearings to improve the motion accuracy.

[0089] In order to improve the stability and reliability of the composite hinge 33-3 during work, the axis of rotation of the third rotating base 333-4 relative to the second rotating base 333-3 is arranged to be coplanar with the axis of the hinge first rotating shaft 3332-1, and the plane is perpendicular to the axis of the hinge second rotating shaft 3333-2; at the same time, the axis of the hinge first rotating shaft 3332-1 is arranged to form a certain angle with the output connecting rod 32-8; the rotating axes of the hinge first rotating shaft 3332-1, the hinge second rotating shaft 3333-2 and the third rotating base 333-4 are arranged to converge at a point, which is the rotation center of the composite hinge 33-3, and the position is kept constant relative to the connecting rod base 333-1. Under this structural layout, the motion of the composite hinge 33-3 can be completely equivalent to that of the spherical hinge 33-1, but it can have a larger rotation range. Specifically, the composite hinge 33-3 can rotate infinitely in the first and third rotating freedom directions, and the rotation range in the second rotating freedom direction is also better than that of the spherical hinge 33-1; at the same time, this structural layout can avoid the singular configuration of the composite hinge 33-3, at which the rotating axes of the hinge first rotating shaft 3332-1 and the third rotating base 333-4 are collinear, and the composite hinge 33-3 only has two orthogonal rotating freedoms; in addition, this structural layout can make the rotation center of the composite hinge 33-3 collinear with the output connecting rod 32-8, so as to reduce the complexity of the mechanism kinematics.

[0090] The working process of the application is as follows:

[0091] In order to facilitate the understanding of the application, the following is combined with Figure 2 The working principle of the novel nine-degree-of-freedom motion redundant parallel mechanism is described in detail:

[0092] Specifically, in this embodiment, the rack fixed platform 1 is arranged in a horizontal plane, and the end moving platform 2 is movably arranged above the rack fixed platform 1.

[0093] According to the inverse kinematics of the novel nine-degree-of-freedom motion redundant parallel mechanism, according to the given motion trajectory (i.e. the position and attitude change function) of the end moving platform 2 and the change function of the redundant degree of freedom configuration (i.e. the change rule of the relative position relationship between the redundant connecting rod 33-2 and the end moving platform 2), the inputs of the first rotating driver 31-1, the second rotating driver 32-1 and the third rotating driver 32-2 in each motion branch chain 3 can be determined. Under the cooperative action of all nine drivers in the three motion branch chains 3, the end moving platform 2 can realize free movement and rotation in a three-dimensional working space.

[0094] Specifically, in each motion branch chain 3:

[0095] In the first serial part 3-1, the output rotating shaft of the first rotating driver 31-1 arranged on the fixed driver support 1-2 rotates and drives the support chain driver support 31-2 fixedly connected to the output rotating shaft to rotate; further, the support chain driver support 31-2 drives the parallel part 3-2 and the second serial part 3-3 arranged thereon to rotate.

[0096] In the parallel part 3-2, the output rotating shafts of the second rotating driver 32-1 and the third rotating driver 32-2 fixedly connected to the support chain driver support 31-2 rotate respectively, and drive the second crank connecting rod 32-4 and the first crank connecting rod 32-3 fixedly connected to the output rotating shafts to rotate in a plane respectively; under the action of the rotation, the first triangular connecting rod 32-5 and the second triangular connecting rod 32-6 move in the plane respectively with the hinge points connected to the second crank connecting rod 32-4 and the first crank connecting rod 32-3 respectively; under the influence of the movement of the two hinge points, the first triangular connecting rod 32-5 and the second triangular connecting rod 32-6 rotate relatively at the hinge points connected to each other; the movement of the second triangular connecting rod 32-6 can change the position of the output connecting rod 32-8 in the plane; the relative rotation of the first triangular connecting rod 32-5 and the second triangular connecting rod 32-6 can change the relative positions of the two vertices connected to the driven connecting rod 32-7 and the output connecting rod 32-8 respectively by the first triangular connecting rod 32-5 and the second triangular connecting rod 32-6 in the plane, further, can change the shape of the triangle composed of the two vertices and the hinge points connected to the driven connecting rod 32-7 and the output connecting rod 32-8, and further, can change the posture of the output connecting rod 32-8 in the plane.

[0097] In this embodiment, the movement plane of the parallel part 3-2 is orthogonal to the rotating shaft of the first rotating driver 31-1 of the first serial part 3-1, and the two degrees of freedom of the movement of the parallel part 3-2 in the plane are also linearly independent of the degrees of freedom of the first serial part 3-1; therefore, under the cooperative action of the first rotating driver 31-1, the second rotating driver 32-1 and the third rotating driver 32-2, the connecting point of the output connecting rod 32-8 and the second serial part 3-3 has three degrees of freedom in space, specifically, three orthogonal movement degrees of freedom.

[0098] In the second serial part 3-3, the working principle of the three-rotation hinge is explained in the mode of the compound hinge 33-3. The connecting rod base 333-1 of the compound hinge 33-3 is fixedly connected with the output connecting rod 32-8; under the cooperation of the three drivers of the motion branch chain 3, the connecting rod base 333-1 also moves in the three-dimensional space, and drives the first rotation base 333-2, the second rotation base 333-3, the third rotation base 333-4, the redundant connecting rod 33-2 and the vertex of the corresponding end moving platform 2 to move together; with the change of the relative position between the connecting rod base 333-1 and the redundant connecting rod 33-2, the relative rotation occurs between the connecting rod base 333-1, the first rotation base 333-2, the second rotation base 333-3 and the third rotation base 333-4.

[0099] On this basis, in order to facilitate further understanding of the present application, the working principle of the redundant degree of freedom of the motion branch chain 3 of the novel nine-degree-of-freedom motion redundant parallel mechanism is explained as follows:

[0100] In a motion branch chain 3, under the cooperation of the drivers, the rotation center of the compound hinge 33-3 can be freely moved in the working space. If the motion trajectory of the rotation center is a circular arc relative to the rack fixed platform 1, the plane where the circular arc is located is perpendicular to the direction of the rotation axis of the redundant connecting rod rotation shaft 332-1, the radius is the vertical distance from the rotation center to the rotation axis of the redundant connecting rod rotation shaft 332-1, and the center of the circle is on the rotation axis of the redundant connecting rod rotation shaft 332-1, then the motion of the motion branch chain 3 will not affect the position and attitude of the end moving platform 2, but only change the configuration of the motion branch chain 3. Therefore, the motion branch chain 3 can actively avoid singularities and other undesirable configurations.

[0101] In this embodiment, the novel nine-degree-of-freedom motion redundant parallel mechanism provided by the present application has high structural stiffness and positioning accuracy; the motion of the mechanism motion branch chain 3 is very flexible, and the end moving platform 2 can have a large working space and a very strong attitude adjustment capability; through the redundant degree of freedom of the motion branch chain 3, the mechanism can actively avoid singularities and undesirable configurations without affecting the motion of the end moving platform 2; at the same time, the parallel arrangement of the rotation shaft of the first rotation driver 31-1 of the motion branch chain 3 with the rack fixed platform 1 can avoid a type of singularities of the motion branch chain 3, further ensuring the continuity of the working space, and this type of singularity occurs when the rotation center of the three-rotation hinge of the second serial part 3-3 is located on the rotation axis of the first rotation driver 31-1.

[0102] The novel nine-degree-of-freedom motion redundant parallel mechanism provided by the present application can select all rotation drivers as step motors, DC motors, brushless motors or rudders and all other drivers that can be used as rotation drivers.

[0103] The above embodiments are the preferred embodiments of the present application, but the embodiments of the present application are not limited to the above embodiments, and any changes, modifications, substitutions, combinations, simplifications, etc. made without departing from the spirit and principles of the present application should be equivalent replacement manners and should be included in the protection scope of the present application.

Claims

1. A novel nine-degree-of-freedom motion redundant parallel mechanism, characterized in that, include: The frame consists of a fixed platform, an end-effector moving platform, and three motion chains. The end-effector platform is positioned opposite to the frame stationary platform, and the two are interconnected by the three motion chains. The three motion chains described are identical in structure, all being hybrid structures. Each of the motion chains has seven degrees of freedom, and its two ends are respectively connected to the frame fixed platform and the end moving platform. The frame platform includes a platform body and three fixed drive brackets, which are distributed circumferentially along the platform body and fixedly connected to it. Each of the aforementioned kinematic branches includes: a first series portion, a parallel portion, and a second series portion; The first series section has one degree of freedom, including a first rotary driver and a branch driver bracket; The first rotary driver is mounted on the fixed driver bracket, and the output shaft is fixedly connected to the branch driver bracket; The parallel section has two degrees of freedom, with the frame end mounted on the branch drive bracket and the output end connected to the second series section. The second series section has four degrees of freedom and is a driven section, including a three-rotation hinge and a redundant link; the three-rotation hinge provides three rotational degrees of freedom; the two ends of the redundant link are respectively connected to the three-rotation hinge and the end moving platform, and the redundant link provides one rotational degree of freedom, which is the redundant degree of freedom of the motion branch; The parallel section includes: a second rotary driver, a third rotary driver, a first crank connecting rod, a second crank connecting rod, a first triangular connecting rod, a second triangular connecting rod, a driven connecting rod, an output connecting rod, a connecting rod shaft pad, and a connecting rod rotation connection assembly; The second rotary driver and the third rotary driver are respectively disposed on both sides of the branch drive bracket, and the output shafts of the second rotary driver and the third rotary driver are respectively fixedly connected to the crank ends of the first crank connecting rod and the second crank connecting rod; The first triangular connecting rod is rotatably connected at three vertices to the connecting rod end of the second crank connecting rod, one vertex of the second triangular connecting rod, and one end of the driven connecting rod, respectively. The second triangular connecting rod is rotatably connected to the connecting rod end of the first crank connecting rod and the middle part of the output connecting rod at the other two vertices that are not connected to the first triangular connecting rod, respectively. One end of the output link is rotatably connected to the driven link, and the other end is fixedly connected to the second series part; The connecting rod rotation connection assembly includes a connecting rod shaft, a connecting rod bearing, and a connecting rod bearing pressure plate; the rotational connection between the first crank connecting rod, the second crank connecting rod, the first triangular connecting rod, the second triangular connecting rod, the driven connecting rod, and the output connecting rod is all achieved through the connecting rod rotation connection assembly; the connecting rod shaft pad is used to compensate for the height difference caused by the thickness of the connecting rod.

2. The novel nine-degree-of-freedom motion redundant parallel mechanism according to claim 1, characterized in that, The three-rotation hinge of the second series section is a ball hinge, including a ball head and a ball seat; the ball head is fixedly connected to the redundant connecting rod, and the ball seat is fixedly connected to the output connecting rod of the parallel section.

3. The novel nine-degree-of-freedom motion redundant parallel mechanism according to claim 1, characterized in that, The three-rotation hinge of the second series section is a composite hinge, including a connecting rod base, a first rotation base, a second rotation base and a third rotation base; The connecting rod base, the first rotating base, the second rotating base and the third rotating base are rotatably connected in sequence; The connecting rod base is fixedly connected to the output connecting rod of the parallel section; The flange end of the third rotating base is fixedly connected to the redundant connecting rod, and the connecting rod end is rotatably connected to the second rotating base.

4. A novel nine-degree-of-freedom motion redundant parallel mechanism according to claim 3, characterized in that, The connecting rod base includes: two identical connecting rod base side plates, two identical output connecting rod pads, a hinge first bearing, a first bearing base, and a first bearing end cap; The two output link pads are respectively fixed to both sides of the output link of the parallel part, and a link base side plate is fixed to the outer side of each of them; The first bearing base is disposed at the end of the connecting rod base away from the output connecting rod, and its two sides are respectively fixedly connected to the side plates of the two connecting rod bases; the first bearing base is provided with a mounting hole for mounting the first hinge bearing, and the first hinge bearing is fixedly connected to the first bearing base at the mounting hole through its outer ring; the first bearing end cap is fixedly connected to the first bearing base, and the two clamp and fix the two sides of the outer ring of the first hinge bearing; the inner ring of the first hinge bearing is fixedly connected to the first rotating base.

5. A novel nine-degree-of-freedom motion redundant parallel mechanism according to claim 3, characterized in that, The first rotating base includes: a first hinge shaft, a second bearing base, a second hinge bearing, and a second bearing end cap; The first pivot of the hinge is rotatably connected to the connecting rod base via the first hinge bearing, and the flange end is fixedly connected to the second bearing base. The second bearing base has a mounting hole for mounting the second hinge bearing, and the second hinge bearing is fixedly connected to the second bearing base at the mounting hole via its outer ring. The second bearing end cap is fixedly connected to the second bearing base, and the two clamp and fix the two sides of the outer ring of the second hinge bearing. The inner ring of the second hinge bearing is fixedly connected to the second rotating base.

6. A novel nine-degree-of-freedom motion redundant parallel mechanism according to claim 3, characterized in that, The second rotating base includes: two identical second base side plates, a second hinge shaft, a hinge shaft washer, a third bearing base, a third hinge bearing, and a third bearing end cap; The flange end of the second hinge shaft is fixedly connected to one of the second base side plates, and the shaft end is rotatably connected to the first rotating base through the second hinge bearing. The hinge shaft washer is disposed on the second hinge shaft to compensate for the height difference between the second hinge bearing and the second base side plate on one side of the hinge shaft end. The third bearing base is disposed at the end of the second rotating base away from the first rotating base, and its two sides are fixedly connected to the two second base side plates respectively. The third bearing base is provided with mounting holes for mounting the third hinge bearing, and the third hinge bearing is fixedly connected to the third bearing base through its outer ring at the mounting holes. The third bearing end cap is fixedly connected to the third bearing base, and the two clamp and fix the two sides of the outer ring of the third hinge bearing. The inner ring of the third hinge bearing is fixedly connected to the connecting rod end of the third rotating base.

7. A novel nine-degree-of-freedom motion redundant parallel mechanism according to claim 1, characterized in that, The redundant link includes a redundant link shaft and a redundant link body; both ends of the redundant link body are fixedly connected to the three rotating hinges of the second series section and the flange end of the redundant link shaft, respectively; the shaft end of the redundant link shaft is rotatably connected to the end moving platform.

8. A novel nine-degree-of-freedom motion redundant parallel mechanism according to claim 7, characterized in that, The end-effector platform includes: a platform body, three identical platform bearing plates, and three identical platform bearings; The bearing pressure plates of the moving platform are distributed circumferentially and fixedly connected to the main body of the moving platform. The moving platform body is provided with mounting holes, which are fixed to the outer ring of the moving platform bearing at the corresponding mounting holes. The moving platform body and the moving platform bearing pressure plate together clamp and fix the two sides of the outer ring of the moving platform bearing. The inner ring of the moving platform bearing is fixedly connected to the shaft end of the redundant connecting rod shaft.

Images