阅读说明：本技术 基于闭环驱动绳索的超冗余联动柔性机械臂 (Super-redundancy linkage flexible mechanical arm based on closed-loop driving rope ) 是由 徐文福 黄健 刘天亮 梁斌 于 2019-08-14 设计创作，主要内容包括：基于闭环驱动绳索的超冗余联动柔性机械臂,包括机械臂组(1)、驱动绳索组(2)和驱动部(3),驱动部(3)牵引驱动绳索组(2),驱动绳索组(2)拉动机械臂组(1)并使其摆动；驱动绳索组(2)包括第一驱动绳索(21)和第二驱动绳索(22),第一驱动绳索(21)的首端(21a)和第二驱动绳索(22)的首端(22a)分别与机械臂组(1)连接；第一驱动绳索(21)的末端(21b)与驱动部(3)连接,第二驱动绳索(22)的末端(22b)穿过绳索中转部(4)与驱动部(3)连接；绳索中转部(4)使第二驱动绳索(22)牵引机械臂组(1)的方向和第一驱动绳索(21)牵引机械臂组(1)的方向相反。本发明能够一定程度上减少驱动部(3)的数量。(The super-redundancy linkage flexible mechanical arm based on the closed-loop driving rope comprises a mechanical arm group (1), a driving rope group (2) and a driving part (3), wherein the driving part (3) pulls the driving rope group (2), and the driving rope group (2) pulls the mechanical arm group (1) and enables the mechanical arm group to swing; the driving rope group (2) comprises a first driving rope (21) and a second driving rope (22), and the head end (21a) of the first driving rope (21) and the head end (22a) of the second driving rope (22) are respectively connected with the mechanical arm group (1); the tail end (21b) of the first driving rope (21) is connected with the driving part (3), and the tail end (22b) of the second driving rope (22) penetrates through the rope transfer part (4) to be connected with the driving part (3); the rope turning part (4) makes the direction in which the second driving rope (22) pulls the arm group (1) opposite to the direction in which the first driving rope (21) pulls the arm group (1). The invention can reduce the number of the driving parts (3) to a certain extent.)

1. The super-redundancy linkage flexible mechanical arm based on the closed-loop driving rope is characterized by comprising

the driving part pulls the driving rope group, and the driving rope group pulls the mechanical arm group to enable the mechanical arm group to swing;

The driving rope group comprises a first driving rope and a second driving rope, and the head end of the first driving rope and the head end of the second driving rope are respectively connected with the mechanical arm group;

The tail end of the first driving rope is connected with the driving part, and the tail end of the second driving rope penetrates through the rope transfer part and is connected with the driving part;

the rope turning part makes the direction in which the second driving rope pulls the arm group opposite to the direction in which the first driving rope pulls the arm group.

2. The closed-loop drive rope based ultra-redundant linked flexible robotic arm of claim 1, wherein the drive portion comprises a first slider and a drive motor driving the first slider to slide;

the first driving rope is arranged in the advancing direction of the first sliding block, and the tail end of the first driving rope is connected to the first sliding block;

The rope transfer portion is disposed in a backward direction of the first slider, and a distal end of the second drive rope passes through the rope transfer portion and is connected to the first slider.

3. The closed loop drive rope based hyper-redundant linked flexible mechanical arm of claim 2, wherein a first pulley and a second pulley are disposed on the first slider;

The end of the first driving rope is fixed to the advancing direction of the first sliding block through the first pulley;

The end of the second drive rope passes through the rope turning portion and the second pulley in this order, and is fixed to the backward direction of the first slider.

4. The closed-loop drive rope based ultra-redundant linkage flexible mechanical arm according to any one of claims 1 to 3, wherein two sets of drive rope sets are connected to one set of mechanical arm set, and are driven by two drive parts respectively;

on the arm group, the first drive rope and the second drive rope of one group of the drive rope groups are respectively arranged on two radial sides of the arm group, and the first drive rope and the second drive rope of the other group of the drive rope groups are also respectively arranged on two radial sides of the arm group;

the first driving ropes and the second driving ropes of the two groups of driving rope groups are uniformly distributed along the circumferential direction of the mechanical arm group.

5. the closed loop drive rope based hyper-redundant linked flexible mechanical arm of claim 4, wherein said sets of arms comprise a plurality of sets, adjacent said sets of arms being articulated by joints.

6. The closed loop drive rope based hyper-redundant linked flexible mechanical arm of claim 5, further comprising a housing, wherein the drive portion comprises a plurality of segments distributed along a circumference of an edge portion of the housing and mounted to the housing.

7. the closed-loop drive rope-based hyper-redundant linked flexible mechanical arm according to claim 6, wherein the rope transit portions comprise a plurality of positions, are distributed along the circumferential direction of the middle portion of the box body, and are mounted on the box body, and the mounting heights of the rope transit portions on the box body are different.

8. The closed-loop drive rope-based super-redundant linkage flexible mechanical arm as claimed in claim 7, further comprising an annular middle swivel base, wherein the middle swivel base is arranged in the middle of the box body, a plurality of mounting seats with different heights are arranged on the middle swivel base, and the rope swivel parts are respectively mounted on the mounting seats.

9. the closed-loop drive rope based ultra-redundant linkage flexible mechanical arm according to claim 8, wherein each rope transit portion comprises two third pulleys, the third pulleys of the same rope transit portion are mounted on the same mounting seat, and the heights of the two mounted third pulleys are the same.

10. The closed-loop drive rope-based ultra-redundant linkage flexible mechanical arm as claimed in claim 9, wherein the mounting seats are respectively provided with two mounting surfaces with the same height at two sides of the middle rotary seat in the radial direction, the mounting surfaces of different mounting seats have different heights, the third pulleys are respectively mounted on the mounting surfaces of the same mounting seat, and the two mounted third pulleys have the same height.

Technical Field

The invention relates to the technical field of robots, in particular to a super-redundancy linkage flexible mechanical arm based on a closed-loop driving rope.

Background

Industrial robots have been widely used in the manufacturing fields of electrical, chemical, mechanical and the like, but are limited by their excessive structure or high rigidity, and conventional multi-joint rigid industrial robots are difficult to adapt to narrow working environments, such as pipeline cleaning and the like. Compared with the traditional mechanical arm, the super-redundancy mechanical arm can realize bending, stretching and twisting of a plurality of continuous parts due to the inherent super-redundancy characteristic, and the motion and operation capability in a narrow space are far better than that of the traditional multi-joint rigid connecting rod robot.

In the super-redundant robot arm, as the number of joints increases, the redundancy of the whole arm also increases, and the number of corresponding driving elements also increases, which also causes difficulty in controlling the robot arm and increases the weight and cost of the robot arm.

disclosure of Invention

The invention provides a super-redundancy linkage flexible mechanical arm based on a closed-loop driving rope, which aims to solve the technical problem of excessive number of motors on a super-redundancy mechanical arm to a certain extent.

The super-redundancy linkage flexible mechanical arm based on the closed-loop driving rope comprises a mechanical arm group, a driving rope group and a driving part, wherein the driving part pulls the driving rope group, and the driving rope group pulls the mechanical arm group and enables the mechanical arm group to swing; the driving rope group comprises a first driving rope and a second driving rope, and the head end of the first driving rope and the head end of the second driving rope are respectively connected with the mechanical arm group; the tail end of the first driving rope is connected with the driving part, and the tail end of the second driving rope penetrates through the rope transfer part and is connected with the driving part; the rope turning part makes the direction in which the second driving rope pulls the arm group opposite to the direction in which the first driving rope pulls the arm group.

Preferably, the driving part comprises a first slider and a driving motor for driving the first slider to slide; the first driving rope is arranged in the advancing direction of the first sliding block, and the tail end of the first driving rope is connected to the first sliding block; the rope transfer portion is disposed in a backward direction of the first slider, and a distal end of the second drive rope passes through the rope transfer portion and is connected to the first slider.

Further preferably, a first pulley and a second pulley are arranged on the first sliding block; the end of the first driving rope is fixed to the advancing direction of the first sliding block through the first pulley; the end of the second drive rope passes through the rope turning portion and the second pulley in this order, and is fixed to the backward direction of the first slider.

Preferably, two sets of the driving rope sets are connected to one set of the mechanical arm set, and the two sets of the driving rope sets are respectively driven by the two driving parts; on the arm group, the first drive rope and the second drive rope of one group of the drive rope groups are respectively arranged on two radial sides of the arm group, and the first drive rope and the second drive rope of the other group of the drive rope groups are also respectively arranged on two radial sides of the arm group; the first driving ropes and the second driving ropes of the two groups of driving rope groups are uniformly distributed along the circumferential direction of the mechanical arm group.

Further preferably, the arm sets include a plurality of sets, and adjacent arm sets are hinged by a joint.

Still further preferably, the device further comprises a box body, and the driving part comprises a plurality of driving parts which are distributed along the circumferential direction of the edge part of the box body and are installed on the box body.

Still further preferably, the rope transit portion includes a plurality of portions, which are distributed along a circumferential direction of a middle portion of the case and are mounted on the case, and mounting heights of the rope transit portion on the case are different.

Preferably, the rope transfer device further comprises an annular middle swivel base, the middle swivel base is arranged in the middle of the box body, a plurality of installation bases with different heights are arranged on the middle swivel base, and the rope transfer portions are respectively installed on the installation bases.

Further preferably, each rope transferring part comprises two third pulleys, the third pulleys of the same rope transferring part are mounted on the same mounting seat, and the two mounted third pulleys are the same in height.

Still further preferably, the mounting seats are respectively provided with two mounting surfaces with the same height on two radial sides of the middle rotating seat, the mounting surfaces of different mounting seats have different heights, the third pulleys are respectively mounted on the mounting surfaces of the same mounting seat, and the two mounted third pulleys have the same height.

According to the super-redundancy linkage flexible mechanical arm based on the closed-loop driving ropes, the rope group is driven by the driving part, and the directions of the first driving rope and the second driving rope in the driving rope group for pulling the mechanical arm group are opposite, so that the mechanical arm group can be driven to swing by one driving part, and the number of the driving parts on the super-redundancy linkage flexible mechanical arm based on the closed-loop driving ropes is reduced to a certain extent.

Drawings

FIG. 1 is a schematic view of one embodiment of a closed loop drive rope based hyper-redundant linked flexible robotic arm;

FIG. 2 is an enlarged view of a portion of FIG. 1A;

FIG. 3 is an exploded view of a joint;

FIG. 4 is a schematic view of one embodiment of a robot arm set;

FIG. 5 is a schematic view of one embodiment of a drive section and drive cord set;

FIG. 6 is a schematic view of another embodiment of a drive section and drive cord set;

Fig. 7 is a partial enlarged view at fig. 6B;

Fig. 8 is a schematic view of an embodiment of a transfer base.

Detailed Description

the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the present invention can be implemented in many different ways and is not limited to the embodiments described herein, but rather these embodiments are provided to enable those skilled in the art to understand the disclosure more thoroughly.

Further, the description of the illustrative embodiments in accordance with the principles of the invention is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description. In describing the embodiments of the invention disclosed, reference to any direction or orientation is intended merely to facilitate explanation and is not intended to limit the scope of the invention in any way. Relative terms such as "front," "back," "upper," "lower," "rear," "outer," "inner," "middle," "inner," "outer," "lower," "upper," "horizontal," "vertical," "above," "below," "up," "down," "top" and "bottom") and derivatives thereof (e.g., "horizontally," "downwardly," "upwardly," etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description only and do not require that the apparatus be constructed or operated in a particular orientation unless otherwise specifically stated. Thus, the invention should not be limited to the exemplary embodiments which illustrate some possible non-limiting combinations of features which may be present alone or in other feature combinations; the scope of protection of the invention is defined by the appended claims.

As presently contemplated, this disclosure describes the best mode or mode of practice of the invention. The present invention is not intended to be understood from the limiting layer, but rather is to be provided as an illustrative example only, in connection with the accompanying drawings, so as to inform those skilled in the art of the advantages and construction of the invention. Like reference characters designate like or similar parts throughout the various views of the drawings.

Fig. 1 is a schematic diagram of an embodiment of a super-redundant linked flexible robotic arm based on closed loop drive cables, fig. 2 is a close-up view at fig. 1A, and fig. 3 is an exploded view of a joint 5. Referring to fig. 1, 2 and 3, the super-redundancy linkage flexible mechanical arm based on the closed-loop driving ropes comprises a mechanical arm group 1, a driving rope group 2 and a driving part 3, wherein the driving part 3 drives the rope group 2, and the driving rope group 2 pulls the mechanical arm group 1 to swing. The arm groups 1 may include a plurality of groups, and adjacent arm groups 1 are connected in series by the joint portion 5. Each arm group 1 may include a plurality of arm rods 11 and a plurality of joints 5, and adjacent arm rods 11 are hinged and connected in series through the joints 5 and pulled through a linkage rope 12 to form an integral arm group 1.

in the following description, an arm positioned on the upper surface of one joint portion 5 is referred to as an upper arm 111, and an arm positioned on the lower surface of the joint portion 5 is referred to as a lower arm 112. The joint section 5 includes three link members 51, the link members 51 include an upper connecting portion 511 and a lower connecting portion 512, the upper connecting portion 511 and the lower end surface 111a of the upper arm lever 111 may be articulated by a universal joint 52a, and the lower connecting portion 512 and the upper end surface 112a of the lower arm lever 112 may also be articulated by a universal joint 52 b. It should be noted that the universal joint may be a known universal joint, or may be a connecting block having two hinge holes perpendicular to each other, and respectively hinge with the connecting rod 51 and the arm 12 to form a universal joint structure. This allows the upper arm lever 111 and the lower arm lever 112 to swing in all directions around the rotation axis of the joint 5.

The upper connecting portions 511 of the three link members 51 are hinged to the upper arm 111 on the lower end surface 111a of the upper arm 111 so as to be evenly distributed at 120 degrees around the axial center of the upper arm 111. The lower connecting portions 512 of the three link members 51 are hinged to the lower arm 112 on the upper end surface 112a of the lower arm 112 so as to be evenly distributed at 120 degrees around the axial center of the lower arm 112. The position where the upper connecting portion 511 and the upper arm link 111 of a single link member 51 are hinged is shifted, for example, 180 degrees, in the circumferential direction of the arm link 11(111, 112) with respect to the position where the lower connecting portion 512 and the lower arm link 112 are hinged, that is, when the upper arm link 111 and the lower arm link 112 are in the coaxial position, assuming that the hinge position of the lower connecting portion 512 and the lower arm link 112 of one link member 51 is 0 degree, the hinge position of the upper connecting portion 511 and the upper arm link 111 of the link member 51 is rotated 180 degrees around the axis of the arm link 11 with respect to the hinge position of the lower connecting portion 512 and the lower arm link 112.

Fig. 4 is a schematic diagram of an embodiment of the arm assembly 1, and referring to fig. 4, each arm 11 in the arm assembly 1 is connected in series by three linkage ropes 12a, 12b, 12c, one end of each linkage rope 12a, 12b, 12c is connected to the uppermost arm 11 in the arm assembly 1, and the other end of each linkage rope 12a, 12b, 12c passes through each joint 5 and each arm 11 in sequence from top to bottom and is connected to the lowermost arm 11 in the arm assembly 1.

Preferably, when the number of the arm links 11 in one arm group 1 is large, the other ends of the three link ropes 12a, 12b, 12c may be connected to the upper end surface of one arm link 11b in the middle of the arm group 1, and then connected to the lowermost arm link 11 in the arm group 1 through another link rope 12d, 12e, 2f from the lower end surface of the last arm link 11a of the arm link 11 b. The three interlocking ropes 12 are also distributed at 120 degrees, respectively, and the directions of the three interlocking ropes 12 can be defined and guided by the three spiral guide pipes 13a, 13b, 13c, respectively, when passing through the respective arms 11. Similarly, the connection position of the upper arm 11 of the arm group 1 of the three interlocking ropes 12a, 12b, and 12c may be shifted in the circumferential direction, for example, by 180 degrees, from the connection position of the lower arm 11 of the arm group 1. Thus, the total length of each of the link ropes 12 is not changed, and when one of the joint portions 5 rotates, the link rope 12 of the joint portion 5 changes, and the link ropes 12 of the other joint portions 5 in the same arm group 1 also change accordingly. Because the three link members 51 are respectively dislocated by 180 degrees, the linkage ropes 12 at the joints 5 mutually form 180 degrees have the same variable quantity, so that the variable quantity of the linkage ropes 12 of each joint 5 is equal, and the linkage effect and the large-angle rotation are realized.

As described above, the driving unit 3 drives the rope group 2, and the driving rope group 2 pulls the arm group 1 to swing. The drive rope group 2 includes a first drive rope 21 and a second drive rope 22, a head end 21a of the first drive rope 21 is connected to the arm group 1, and a head end 22a of the second drive rope 22 is also connected to the arm group 1. The end 21b of the first drive rope 21 is connected to the drive unit 3, the end 22b of the second drive rope 22 is connected to the drive unit 3 through the rope transfer unit 4, and the rope transfer unit 4 causes the direction in which the second drive rope 22 pulls the arm group 1 to be opposite to the direction in which the first drive rope 21 pulls the arm group 1. Thus, a closed-loop driving route is formed among the driving unit 3, the first driving rope 21, the arm group 1, the second driving rope 22 and the rope transit unit 4, and when the driving unit 3 drives the first driving rope 21 to pull the arm group 1, the swing of the arm group 1 simultaneously actively pulls the second driving rope 22, and when the driving unit 3 drives the second driving rope 22 to pull the arm group 1, the swing of the arm group 1 simultaneously actively pulls the first driving rope 21. In this way, the two drive ropes 21 and 22 can be simultaneously driven by one drive unit 3, and the arm group 1 can be stably swung.

Fig. 5 is a schematic view of an embodiment of the drive part 3 and the drive rope set 2. Referring to fig. 5, the driving part 3 preferably includes a first slider 31, a driving motor 32 driving the first slider 31 to slide, and a transmission mechanism 33. The drive motor 32 slides the first slider 31 by driving the transmission mechanism 33. In order to facilitate the installation of the driving part 3, a case 6 may be further provided, and the case 6 includes an upper case plate 61, a middle case plate 62, and a lower case plate 63, which are respectively disposed from top to bottom. The driving motor 32 is mounted on the lower box plate 63, the transmission mechanism 33 includes a screw transmission assembly 331 and a linear slide rail 332, and the first slider 31 is mounted on the linear slide rail 332 and connected with a screw nut 331a of the screw transmission assembly 331. The two ends of the screw driving unit 331 are supported to the upper case plate 61 and the middle case plate 62 through bearing seats 333 and 334, respectively. Similarly, the two ends of the linear guideway 332 are also fixed to the upper box plate 61 and the middle box plate 62, respectively, and the driving motor 32 and the lead screw transmission assembly 331 are coupled by a coupler.

For convenience of the following description, a direction in which the driving motor 32 drives the first slider 31 to approach the arm group 1 is referred to as a forward direction of the first slider 31, and a direction in which the driving motor 32 drives the first slider 31 to separate from the arm group 1 is referred to as a backward direction of the first slider 31.

The first drive rope 21 is disposed in the advancing direction of the first slider 31, the head end 21a of the first drive rope 21 is attached to the arm unit 1, the tail end 21b of the first drive rope 21 is attached to the first slider 31, and the tail end 21b of the first drive rope 21 may be directly fixed to the first slider 31. When the drive motor 32 drives the first slider 31 to move backward so that the entire first drive rope 21 is in the forward direction of the first slider 31, the first drive rope 21 pulls the arm group 1 and swings around the joint 5.

The rope transit portion 4 is provided in the retreating direction of the first slider 31, the rope transit portion 4 can be attached to the case 6, and although the stroke by which the first slider 31 can retreat may be large, the rope transit portion 4 is provided outside the stroke by which the first slider 31 can retreat to ensure that the second drive rope 22 does not fall off from the rope transit portion 4. The rope transit 4 may be mounted on the middle box plate 62 or the lower box plate 63, for example, the middle rotating base 7 may be mounted on the middle box plate 62, the rope transit 4 includes at least one pulley (also referred to as a third pulley 41 for convenience of distinction), the third pulley 41 is supported by a shaft to the middle rotating base 7, a head end 21a of the second driving rope 22 is also connected to the arm assembly 1, and a tail end 22b of the second driving rope 22 passes through the rope transit 4 and is connected to the first slider 31. That is, the second drive rope 22 is connected to the first slider 31 from the backward direction of the first slider 31 via the guide of the third pulley 41. The first ends 21a and 22a of the first and second drive ropes 21 and 22 are provided on both sides of the arm group 1 in the radial direction, respectively, and are symmetrical with respect to the rotation axis ZX of the joint portion 5. As a result, when the first slider 31 advances, the second drive rope 22 is pulled by the first slider 31, and the arm unit 1 is pulled to swing (to the right side as viewed in the drawing), and at the same time, the arm unit 1 and the first drive rope 21 are also in a state of being tensioned to each other, and therefore, the arm unit 1 can be stably swung. Similarly, when the first slider 31 moves backward, the first drive rope 21 is pulled by the first slider 31, and the arm unit 1 is pulled and swung (to the right and left in the drawing), and at the same time, the arm unit 1 and the second drive rope 22 are pulled close to each other, so that the arm unit 1 can be stably swung. Furthermore, since the first drive rope 21 and the second drive rope 22 are driven by the same drive motor 32, the expansion and contraction lengths and speeds of the two drive ropes 21 and 22 can be ensured to be uniform, and any compensation from the aspect of control is not needed.

Fig. 6 is a schematic view of another embodiment of the drive portion 3 and the drive rope set 2, and fig. 7 is a partial enlarged view at fig. 6B. Referring to fig. 6 and 7, in order to shorten the driving stroke of the driving unit 3, the structure of the housing 6 is further made compact, and the weight of the entire robot arm is reduced. The first slider 31 is provided with two pulleys (also referred to as a first pulley 311 and a second pulley 312 for convenience of distinction). Wherein the distal end 21b of the first drive rope 21 is fixed to the advancing direction of the first slider 31 through the first pulley 311, for example, to the upper case plate 61. The distal end 22b of the second drive rope 22 passes through the rope transit portion 4 and the second pulley 312 in this order, and is fixed to the retreating direction of the first slider 31, for example, to the middle box plate 62. Accordingly, when the first slider 31 slides, the first drive rope 21 and the second drive rope 22 extend and contract in a stroke twice as long as the sliding stroke of the first slider 31, and therefore, the driving stroke of the driving section 3 can be shortened in a double manner without changing the swing angle of the arm assembly 1, and the structure of the housing 6 in which the driving section 3 is incorporated can be made more compact.

In order to further reduce the number of the driving parts 3 of the arm group 1 and to allow more freedom in swinging the arm group 1, it is preferable that two sets of driving ropes 2, 2a are connected to one set of arm group 1, and the two sets of driving ropes 2, 2a are driven by the two driving parts 3, respectively. On the arm group 1, the first drive ropes 21 and the second drive ropes 22 of one set of drive rope groups 2 are respectively disposed on both sides in the radial direction of the arm group 1, the first drive ropes 21a and the second drive ropes 22a of the other set of drive rope groups 2a are also respectively disposed on both sides in the radial direction of the arm group 1, and the first drive ropes 21, 21a and the second drive ropes 22, 22a of the two sets of drive rope groups 2, 2a are uniformly distributed in the circumferential direction of the arm group 1. That is, the same arm group 1 is connected to four drive ropes 21, 21a, 22, and 22a, and the four drive ropes 21, 21a, 22, and 22a are distributed at 90-degree angular intervals in the circumferential direction of the arm group 1 around the rotation axis of the joint 5. Thus, different combinations of forward and backward movements of the two first sliders 31 driven by the two drive motors 32 can be realized, and the swing of the arm group 1 at each angle can be realized.

Fig. 8 is a schematic view of an embodiment of the middle rotating base 7, referring to fig. 8 and with continued reference to fig. 1, as described above, the arm assembly 1 may include a plurality of segments, each of which is hinged by the joint portion 5, and when the arm assembly 1 includes a plurality of segments, the driving portion 3 may also include a plurality corresponding to the number of the arm assemblies 1. Preferably, the case 6 may have a cylindrical shape, and the driving portion 3 is attached to the case 6 along a circumferential direction of a radial edge portion 6a of the case 6.

Further preferably, the rope transit portion 4 may include a plurality of portions corresponding to the number of the driving portions 3, and be attached to the case 6 in the circumferential direction of the middle portion 6b in the radial direction of the case 6. Preferably, the middle rotating base 7 for mounting the third pulley 41 of the rope transit 4 may have a ring shape, and the middle rotating base 7 is disposed at a middle portion of the case 6, for example, at a middle portion of the middle case plate 62. Since the first drive rope 21 and the second drive rope 22 are respectively disposed at two radial sides of the arm assembly 1, and are symmetrical to each other, when the end 22b of the second drive rope 22 is connected to the drive part 3, it is necessary to pass around the case 6 from one radial side of the case 6 to connect to the drive part 3 located at the other radial side of the case 6. In order to solve this problem, since the interference is likely to occur between the different second drive ropes 22 when the drive rope group 2 includes a plurality of groups, the housing 6 may be provided with the mount seats 71 having different mount heights, and the rope transit portions 4 may be mounted on the different mount seats 71 so that the mount heights of the rope transit portions 4 are different from each other, thereby avoiding the interference between the second drive ropes 22. Further preferably, each rope transit 4 comprises two third pulleys 41a, 41b, respectively, and the third pulleys 41a, 41b are mounted on the same mounting seat 71, respectively, and the two mounted third pulleys 41 have the same height. Still more preferably, the mounting seat 71 is provided with two mounting surfaces 711a and 711b having the same height on two sides of the transfer seat 7 in the radial direction, the mounting surfaces 711 of different mounting seats 71 have different heights, the third pulleys 41a and 41b are mounted on the mounting surfaces 711a and 711b of the same mounting seat 71 (i.e., having the same height), and the two mounted third pulleys 41a and 41b have the same height. By providing the two third pulleys 41a and 41b, the second drive rope 22 can be changed from extending in the axial direction of the casing 6 to extending in the radial direction of the casing 6, and can be made to reach the first slider 31.

Further, a guide seat 8 may be provided above the relay seat 7, the guide seat 8 may be provided with a plurality of guide holes 81 for allowing the second drive ropes 22 to pass therethrough, respectively, and the guide seat 8 may be locked to the relay seat 7 to fix the support shaft 42 of each third pulley 41. When the guide base 8 and the middle rotary base 7 are locked with each other, the guide holes 81 on the guide base 8 are respectively located above the third pulleys 41 of the middle rotary base 7.

The various features described in the foregoing detailed description may be combined in any manner and, for the sake of unnecessary repetition, various combinations are not intended to be encompassed by the invention.

The above embodiments are merely illustrative of the technical solutions of the present invention and are not restrictive, and any modifications or equivalent substitutions which do not depart from the scope of the present invention should be included in the technical solutions of the present invention.