WO2023138071A1

WO2023138071A1 - Under-actuated continuum mechanical arm

Info

Publication number: WO2023138071A1
Application number: PCT/CN2022/118022
Authority: WO
Inventors: 张庭; 宁传新; 李阳; 冯凯祥; 巩振华; 唐庆康
Original assignee: 苏州大学
Priority date: 2022-01-19
Filing date: 2022-09-09
Publication date: 2023-07-27
Also published as: CN114407074A; CN114407074B

Abstract

An under-actuated continuum mechanical arm, which comprises three driving motors (4, 5, 6), three driving ropes (1, 2, 3), and a plurality of sequentially connected joints (7); each joint (7) comprises a dynamic platform (71) and a static platform (72); three driven ropes (73) are connected on the dynamic platform (71) in each joint (7); each joint (7) is connected to three variable diameter driving mechanisms (8), the driven ropes (73) and the variable diameter driving mechanisms (8) in each joint (7) are in one-to-one correspondence, and each driven rope (73) in each joint (7) is connected to an output end of a corresponding variable diameter driving mechanism (8); the variable diameter driving mechanisms (8) comprise variable diameter pulleys (81), and the variable diameter pulleys (81) comprise variable diameter outer annular bodies (811); and the outer annular bodies (811) of the variable diameter pulleys (81) in the variable diameter driving mechanisms (8) at each joint (7) are all driven by corresponding driving ropes (1, 2, 3) to rotate. As a consequence, the present invention has a simple arrangement structure, is low in overall weight and small in size, and the flexibility and the load capacity of a mechanical arm can also be effectively ensured.

Description

An underactuated continuum manipulator

technical field

The invention relates to the technical field of mechanical arms, in particular to an underactuated continuum mechanical arm.

Background technique

The continuum manipulator has a long and thin shape as a whole, and is composed of multiple subsections connected in series. The components of each subsection often have greater flexibility, which makes the continuum manipulator have good compliance characteristics and flexibility. In view of the above characteristics of the continuum manipulator, the continuum manipulator is widely used in various fields.

The patent application announcement number is a Chinese patent with CN108237524A. A line -driven continuous robot is disclosed. The robot includes the driver system and the robotic arm. The robotic arm includes multiple single -joint blocks connected in turn. The motivation is connected, and the other end is fixed through the robotic arm and is fixed with the end of the robotic arm. The drive system drives the robotic arm to generate side bending or telescopic deformation to achieve the grasp of the target. However, the movement space of the whole mechanical arm of the above-mentioned structure is small, and the degree of freedom is low.

The Chinese patent application publication number is CN105014689A, which discloses a rope-driven continuum mechanical arm and robot with motion decoupling, including a plurality of mechanical arm sleeves, traction rope sets and joints; multiple mechanical arm sleeves are arranged in sequence and adjacent mechanical arm sleeves are hinged to form a mechanical arm body; the front end of the mechanical arm body is used to connect the wire rope to drive the base; After passing through the through holes arranged on the rope guide discs of a plurality of joints on the front side of the corresponding joints, the base is connected with a wire rope to drive the base. The above-mentioned mechanical arm uses ropes to run through the whole mechanism, and each rope is driven by a motor. Hooke hinges are used between the driving units. The driving device is too large, and there are too many driving ropes, which makes the overall mechanism too complicated. Moreover, due to the rigid structure, continuous deformation cannot be achieved, the flexibility is not good, and the application places are limited.

The Chinese patent with the publication number of patent application CN112873190A discloses a continuous tensegrity robot driven by multi-section ropes, including a base, a plurality of basic units, a plurality of connection structures and three driving mechanisms arranged in front and back. The centers of the basic units are provided with elastic connectors, which are elastically connected to the basic units; the driving mechanism includes a plurality of ropes and a plurality of driving units for driving the movement of the ropes, and the front ends of the ropes are connected to the driving units. The structure of the manipulator is mainly composed of multiple basic units connected in series. The center of each basic unit is equipped with an elastic connector, which is elastically connected to the basic unit and can be bent in multiple directions. However, due to the use of elastic connectors between each basic unit, the overall motion stability of the mechanical arm is poor, and the working pressure is low, so the output force is small and the load capacity is weak.

To sum up, for the existing continuum manipulators driven by ropes, if there are too few driving ropes, the movement of the mechanism will be inflexible and the degree of freedom will be low. If there are too many driving ropes, the overall structure will be more complicated, and the overall load capacity will also be weak. Moreover, since each drive unit of the manipulator needs to use multiple drivers in parallel, it will also lead to more drives, which increases the overall weight and volume of the manipulator, and cannot meet the needs of use.

Contents of the invention

Therefore, the technical problem to be solved by the present invention is to overcome the defect that the continuum manipulator in the prior art cannot simplify the structure and reduce the overall weight and volume of the manipulator on the basis of ensuring flexibility and load capacity.

In order to solve the above-mentioned technical problems, the present invention provides an underactuated continuum mechanical arm, which includes three drive motors, three drive ropes and a plurality of sequentially connected joints, and the drive motors correspond to the drive ropes one by one;

Each of the joints includes a dynamic platform and a static platform, and the dynamic platform and the static platform are connected by a spherical pair; the dynamic platform in each of the joints is connected with three driven ropes;

Each of the joints is connected with three variable-diameter drive mechanisms, the driven rope in each of the joints corresponds to the variable-diameter drive mechanism, and each of the driven ropes in each of the joints is connected to the output end of the corresponding variable-diameter drive mechanism;

The variable-diameter driving mechanism includes a variable-diameter pulley, and the variable-diameter pulley includes an outer ring body with a variable diameter;

The outer ring body of the variable diameter pulley in the first variable diameter drive mechanism at each joint is driven to rotate by the first drive rope;

The outer ring body of the variable diameter pulley in the second variable diameter drive mechanism at each joint is driven to rotate by the second drive rope;

The outer ring body of the variable-diameter pulley in the third variable-diameter drive mechanism at each joint is driven to rotate by the third drive rope.

In one embodiment of the present invention, the variable-diameter driving mechanism further includes a fixed plate and a movable plate, the movable plate is movably connected to the fixed plate, and the movable plate is driven by a pushing device to move relative to the fixed plate; the variable-diameter pulley includes an inner bracket and a plurality of arc plates, the inner bracket is connected to the fixed plate, all the arc plates surround the inner bracket to form the outer ring body, each of the arc plates is connected to the inner bracket through an elastic member, and the moving direction of the movable plate is connected to the outer ring. The axes of the rings are parallel, and each of the circular arc plates abuts at least one tensioning rope, one end of the tensioning rope is connected to the fixed plate body, and the other end is connected to the movable plate body.

In one embodiment of the present invention, the pushing device adopts a lead screw nut transmission mechanism, the lead screw nut transmission mechanism includes a lead screw and a drive nut, the drive nut is screwed on the lead screw and can move linearly along the lead screw, the drive nut is connected to the movable plate body, the lead screw is connected to the inner bracket through a bearing, and the lead screw is driven to rotate by an auxiliary motor.

In one embodiment of the present invention, the inner bracket includes an inner ring body and a plurality of limiting sleeves, each of the circular arc plates is connected with a limiting rod, the limiting rods correspond to the limiting sleeves one by one, the limiting rods can be slidably connected in the corresponding limiting sleeves, the limiting sleeves are connected to the outer wall of the inner ring body, and one elastic member is connected between each limiting rod and the corresponding limiting sleeve.

In one embodiment of the present invention, a limiting plate is provided at one end of the limiting rod facing the inner ring body, one end of the elastic member is connected to the limiting plate, and the other end abuts against the corresponding limiting sleeve.

In one embodiment of the present invention, the elastic member is a compression spring.

In one embodiment of the present invention, the fixed plate is connected with an output sheave, one end of the driven rope in each joint is wound on the output sheave of the corresponding variable diameter drive mechanism, and the other end is connected with the moving platform.

In one embodiment of the present invention, two adjacent joints are connected by a connecting rod, one end of the connecting rod between two adjacent joints is connected to the dynamic platform of one joint, and the other end is connected to the static platform of the adjacent joint.

In one embodiment of the present invention, a first support rod is connected to the moving platform, a second support rod is connected to the static platform, and the first support rod and the second support rod in each joint are connected through a spherical pair.

In one embodiment of the present invention, a rope hole corresponding to the driven rope is provided on the moving platform of each joint, and the driven rope is connected in the corresponding rope hole.

The above technical solution of the present invention has the following advantages compared with the prior art:

The continuum manipulator of the above-mentioned embodiment of the present invention has a simple structure, which not only reduces the number of motors required by the continuum manipulator, greatly reduces the overall weight and volume of the continuum manipulator, but also effectively ensures the flexibility and load capacity of the manipulator, so that the manipulator can work in a complex environment and has a certain load-carrying and fine operation ability, so that the manipulator can achieve a high load-to-weight ratio under the condition of light weight.

Description of drawings

In order to make the content of the present invention more clearly understood, the present invention will be further described in detail below according to the specific embodiments of the present invention and in conjunction with the accompanying drawings.

Fig. 1 is the structural representation of the underactuated continuum mechanical arm of the present invention;

Fig. 2 is a schematic structural view of the variable-diameter drive mechanism in Fig. 1;

Fig. 3 is a schematic top view of the variable diameter pulley in Fig. 1;

Fig. 4 is the schematic diagram of the structure of the cooperation of variable diameter pulley and tension rope in Fig. 3;

Fig. 5 is a schematic structural view of the joint in Fig. 1;

Fig. 6 is a schematic structural view of the moving platform in Fig. 5;

Fig. 7 is a schematic structural view of the static platform in Fig. 5;

Explanation of reference signs in the manual:

1. The first driving rope; 2. The second driving rope; 3. The third driving rope; 4. The first main driving motor; 5. The second main driving motor; 6. The third main driving motor;

7, joint; 71, moving platform; 711, first installation hole; 712, rope hole; 713, first support rod; 72, static platform; 721, second installation hole; 722, second support rod; 73, driven rope;

8. Variable diameter drive mechanism; 81. Variable diameter pulley; 811. Outer ring body; 8111. Arc plate; 8112. Limit rod; 8113. Limit plate; 812. Inner support; 8121. Inner ring body; 8122. Limit sleeve; wheel;

9. Connecting rod.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and implement it, but the examples given are not intended to limit the present invention.

Referring to Figure 1, this embodiment discloses an underactuated continuum mechanical arm, which includes three drive motors, three drive ropes and a plurality of sequentially connected joints 7, and the drive motors correspond to the drive ropes one by one;

Each joint 7 includes a moving platform 71 and a static platform 72, which are connected by a spherical pair between the moving platform 71 and the static platform 72; three driven ropes 73 are connected to the moving platform 71 in each joint 7, so that power is transmitted to the moving platform 71 by the driven rope 73;

Each joint 7 is connected with three variable-diameter drive mechanisms 8 to drive the joint 7 to move. The driven rope 73 in each joint 7 corresponds to the variable-diameter drive mechanism 8. Each driven rope 73 in each joint 7 is connected to the output end of the corresponding variable-diameter drive mechanism 8. That is, the driven rope 73 is pulled by the variable-diameter drive mechanism 8, so that the moving platform 71 moves;

The variable-diameter driving mechanism 8 includes a variable-diameter pulley 81, and the variable-diameter pulley 81 includes a variable-diameter outer ring body 811;

The outer ring body 811 of the variable diameter pulley 81 in the first variable diameter drive mechanism 8 at each joint 7 is driven to rotate by the first drive rope 1; during installation, it is only necessary to make the first drive rope 1 go around the outer ring body 811 of the variable diameter pulley 81 in the first variable diameter drive mechanism 8 at each joint 7 in turn;

The outer ring body 811 of the variable-diameter pulley 81 in the second variable-diameter drive mechanism 8 at each joint 7 is driven to rotate by the second drive rope 2; during installation, it is only necessary to make the second drive rope 2 go around the outer ring body 811 of the variable-diameter pulley 81 in the second variable-diameter drive mechanism 8 at each joint 7 in turn;

The outer ring body 811 of the variable diameter pulley 81 in the third variable diameter drive mechanism 8 at each joint 7 is driven to rotate by the third drive rope 3;

The variable-diameter pulley 81 in the variable-diameter drive mechanism 8 in the above structure has an outer ring body 811 with a variable diameter. By changing the diameter of the outer ring body 811, the output speed of the variable-diameter drive mechanism 8 can be changed. The entire variable-diameter driving mechanism 8 where the body 811 is located rotates together. When the diameter of the outer ring body 811 becomes larger, the overall output speed of the outer ring body 811 and the variable-diameter driving mechanism 8 where it is located becomes smaller. The joint 7 is driven by the same drive motor but has different effects of different rotation amplitudes, which realizes the power input on a drive rope, and can be changed to different speed outputs by the variable diameter pulley 81.

In addition, three driven ropes 73 are connected to the moving platform 71 of each joint 7, and each driven rope 73 is pulled and driven by an independent variable-diameter driving mechanism 8, thereby effectively realizing the three-degree-of-freedom movement of the moving platform 71 and effectively ensuring the movement flexibility of the joint 7. By controlling the pulled amount of the three driven ropes 73, the moving platform 71 can produce different swing angles.

Only three driving motors are used as the active input in the above-mentioned mechanical arm, which effectively reduces the number of driving motors placed on the joint 7 of the mechanical arm, thereby greatly reducing the overall weight and volume of the entire mechanical arm and improving its rapid response capability; and only three driving ropes and the variable-diameter driving mechanism 8 can be used to achieve multi-degree-of-freedom motion, which not only ensures the flexibility of the joint 7 movement, but also makes the structure of the mechanical arm simpler; at the same time, the above-mentioned mechanical arm also has better load capacity.

In one of the implementations:

As shown in Fig. 2, Fig. 3 and Fig. 4, the variable-diameter driving mechanism 8 also includes a fixed plate body 82 and a movable plate body 83, the movable plate body 83 is movably connected to the fixed plate body 82, and the movable plate body 83 is driven by a pushing device 84 to move relative to the fixed plate body 82;

The variable diameter pulley 81 includes an inner bracket 812 and a plurality of arc plates 8111, the inner bracket 812 is connected with the fixed plate body 82, and all the arc plates 8111 in the variable diameter pulley 81 are enclosed outside the inner bracket 812 to form an outer ring body 811, and each arc plate 8111 is connected with the inner bracket 812 through an elastic member 813; The pulley 81 rotates together;

The moving direction of the movable plate body 83 is parallel to the axis of the outer ring body 811, and each circular arc plate 8111 abuts against at least one tensioning rope 85, one end of the tensioning rope 85 is connected with the fixed plate body 82, and the other end is connected with the movable plate body 83.

For example, the tension cord 85 abuts against the inner side of the outer ring body 811 .

When the pushing device 84 drives the movable plate body 83 to move away from the fixed plate body 82, the distance between the fixed plate body 82 and the movable plate body 83 becomes larger, and the tension rope 85 is gradually tightened. At this time, the tension rope 85 drives each circular arc plate 8111 to move outward, so that the diameter of the outer ring body 811 becomes larger. During this process, each elastic member 813 in the variable diameter drive mechanism 8 is in a stretched state;

When the pushing device 84 drives the movable plate body 83 to move towards the fixed plate body 82, the distance between the fixed plate body 82 and the movable plate body 83 becomes smaller, and the tension rope 85 becomes more and more loose.

In one of the embodiments, the outer wall of each arc plate 8111 is provided with an arc-shaped rope groove, and the arc-shaped rope grooves of all the arc-shaped plates 8111 in the variable diameter pulley 81 surround and form an annular groove on the outer ring body 811 for the corresponding driving rope to wind.

In one of the embodiments, the pushing device 84 adopts a screw 841 nut transmission mechanism. The screw 841 nut transmission mechanism includes a screw 841 and a drive nut. The drive nut is screwed on the screw 841 and can move linearly along the screw 841. In each variable diameter drive mechanism 8, the drive nut is connected to the movable plate body 83. The screw 841 is driven by an auxiliary motor (not shown). Can not drive inner bracket 812 to rotate during.

The driving motor drives the lead screw 841 to rotate, and the rotation of the lead screw 841 will make the drive nut and the movable plate body 83 move linearly along the lead screw 841, thereby changing the distance between the fixed plate body 82 and the movable plate body 83, thereby changing the tension state of the tension rope 85 between the fixed plate body 82 and the movable plate body 83.

In one of the embodiments, in each variable-diameter pulley 81: the inner bracket 812 includes an inner ring body 8121 and a plurality of limit sleeves 8122, each circular arc plate 8111 is connected with a limit rod 8112, each limit rod 8112 corresponds to the limit sleeve 8122, and the limit rods 8112 can be slidably connected to the corresponding limit sleeve 8122, and the limit sleeves 8122 are connected to the outer wall of the inner ring body 8121 Above, an elastic member 813 is connected between each limiting rod 8112 and the corresponding limiting sleeve 8122 .

When the limiting rod 8112 moves outward relative to the limiting sleeve 8122, the diameter of the outer ring body 811 formed by the plurality of arc plates 8111 becomes larger; otherwise, the diameter of the outer ring body 811 becomes smaller.

In one embodiment, a limiting plate 8113 is provided at one end of the limiting rod 8112 toward the inner ring body 8121 , one end of the elastic member 813 is connected to the limiting plate 8113 , and the other end abuts against the end of the corresponding limiting sleeve 8122 . The setting of the limiting plate 8113 can limit the elastic member 813 and prevent it from slipping.

Further, the limiting plate 8113 can be T-shaped.

Further, the inner ring body 8121 is connected with the lead screw 841 through a bearing.

In one embodiment, the plurality of arc plates 8111 outside the inner bracket 812 are evenly distributed in the circumferential direction.

In one embodiment, the elastic member 813 is a compression spring, and other elastic elements may also be used.

In one of the embodiments, the fixed plate body 82 is connected with an output sheave 86, and one end of the driven rope 73 in each joint 7 is wound on the output sheave 86 of the corresponding variable diameter driving mechanism 8, and the other end is connected with the moving platform 71. When the variable-diameter pulley 81 in the variable-diameter drive mechanism 8 rotates under the drive of the drive rope, it will drive the fixed plate body 82 and the output sheave 86 to rotate together.

In one of the embodiments, two adjacent joints 7 are connected by a connecting rod 9, one end of the connecting rod 9 between two adjacent joints 7 is connected to the dynamic platform 71 of one joint 7, and the other end is connected to the static platform 72 of the adjacent joint 7.

Specifically, as shown in FIGS. 6-7 , the middle part of the moving platform 71 is provided with a first installation hole 711, and the middle part of the static platform 72 is provided with a second installation hole 721. One end of the connecting rod 9 between two adjacent joints 7 is connected to the first installation hole 711 on the moving platform 71 of a joint 7, and the other end is connected to the second installation hole 721 on the static platform 72 of the adjacent joint 7.

Further, a detachable connection is adopted between the connecting rod 9 and the moving platform 71, and a detachable connection is also adopted between the connecting rod 9 and the static platform 72 of the adjacent joint 7; the above-mentioned structure is convenient for installation and disassembly, which is beneficial to the expansion of multiple joints 7, and realizes the different length requirements of the continuum manipulator. The detachable connection can be threaded.

In one of the embodiments, as shown in FIG. 5 , a first support rod 713 is connected to the moving platform 71 , a second support rod 722 is connected to the static platform 72 , and the first support rod 713 and the second support rod 722 in each joint 7 are connected by a spherical pair.

In one of the embodiments, as shown in FIG. 6 , the moving platform 71 of each joint 7 is provided with a rope hole 712 corresponding to the driven rope 73, and the driven rope 73 is connected in the corresponding rope hole 712, that is, each moving platform 71 is provided with three rope holes 712, and each rope hole 712 corresponds to a driven rope 73. One end of the driven rope 73 is fixed in the corresponding rope hole 712, and the other end is connected to the output end of the corresponding variable diameter drive mechanism 8.

Further, as shown in FIG. 6 , the plurality of rope holes 712 on the moving platform 71 are evenly distributed in the circumferential direction.

The continuum manipulator of the above embodiment is driven by ropes, and three driving ropes are pulled by three driving motors and wound in turn in the corresponding variable-diameter driving mechanisms at each joint, and output by each variable-diameter driving mechanism at different speeds, thereby driving the moving platform of each joint to swing at different angles to meet the needs of different motion modes. The robotic arm as a whole uses only three driving motors as active inputs, and each joint has three degrees of freedom. This not only reduces the number of motors required for the continuum robotic arm, but also greatly reduces the overall weight and size of the continuum robotic arm. At the same time, it can effectively ensure the flexibility and stiffness of the robotic arm, meet the load requirements of the robotic arm, enable the robotic arm to work in complex environments and have a certain load-carrying and fine-handling capability, and enable the robotic arm to achieve a high load-to-weight ratio with a light weight.

Apparently, the above-mentioned embodiments are only examples for clear description, and are not intended to limit the implementation. For those of ordinary skill in the art, on the basis of the above description, other changes or changes in various forms can also be made. It is not necessary and impossible to exhaustively list all the implementation manners here. However, the obvious changes or changes derived therefrom are still within the scope of protection of the present invention.

Claims

An underactuated continuum mechanical arm is characterized in that: it comprises three driving motors, three driving ropes and a plurality of sequentially connected joints, and the driving motors and the driving ropes correspond one-to-one;

Each of the joints includes a dynamic platform and a static platform, and the dynamic platform and the static platform are connected by a spherical pair; the dynamic platform in each of the joints is connected with three driven ropes;

Each of the joints is connected with three variable-diameter drive mechanisms, the driven rope in each of the joints corresponds to the variable-diameter drive mechanism, and each of the driven ropes in each of the joints is connected to the output end of the corresponding variable-diameter drive mechanism;

The variable-diameter driving mechanism includes a variable-diameter pulley, and the variable-diameter pulley includes an outer ring body with a variable diameter;

The outer ring body of the variable diameter pulley in the first variable diameter drive mechanism at each joint is driven to rotate by the first drive rope;

The outer ring body of the variable diameter pulley in the second variable diameter drive mechanism at each joint is driven to rotate by the second drive rope;

The outer ring body of the variable-diameter pulley in the third variable-diameter drive mechanism at each joint is driven to rotate by the third drive rope.
The underactuated continuum mechanical arm according to claim 1, characterized in that: the variable-diameter drive mechanism also includes a fixed plate and a movable plate, the movable plate is movably connected to the fixed plate, and the movable plate is driven by a pushing device to move relative to the fixed plate; the variable-diameter pulley includes an inner support and a plurality of arc plates, the inner support is connected to the fixed plate, and all the arc plates surround the inner support to form the outer ring, and each of the arc plates is connected to the inner support through an elastic member. The moving direction of the plate body is parallel to the axis of the outer ring body, and each arc plate abuts at least one tensioning rope, one end of the tensioning rope is connected with the fixed plate body, and the other end is connected with the movable plate body.
The underactuated continuum mechanical arm according to claim 2, wherein the pushing device adopts a screw nut transmission mechanism, the screw nut transmission mechanism includes a screw and a transmission nut, the transmission nut is screwed on the screw and can move linearly along the screw, the transmission nut is connected to the movable plate, the screw is connected to the inner bracket through a bearing, and the screw is driven to rotate by an auxiliary motor.
The underactuated continuum mechanical arm according to claim 2, wherein the inner support includes an inner ring body and a plurality of limit sleeves, each of the circular arc plates is connected with a limit rod, the limit rods correspond to the limit sleeves one by one, the limit rods can be slidably connected in the corresponding limit sleeves, the limit sleeves are connected to the outer wall of the inner ring body, and one elastic member is connected between each limit rod and the corresponding limit sleeve.
The underactuated continuum mechanical arm according to claim 4, wherein a limit plate is provided at one end of the limit rod facing the inner ring body, one end of the elastic member is connected to the limit plate, and the other end abuts against the corresponding limit sleeve.
The underactuated continuum mechanical arm according to claim 2, wherein the elastic member is a compression spring.
The underactuated continuum mechanical arm according to claim 2, wherein an output sheave is connected to the fixed plate, one end of the driven rope in each joint is wound on the output sheave of the corresponding strain diameter drive mechanism, and the other end is connected to the moving platform.
The underactuated continuum mechanical arm according to claim 1, wherein two adjacent joints are connected by a connecting rod, one end of the connecting rod between two adjacent joints is connected to the dynamic platform of one joint, and the other end is connected to the static platform of the adjacent joint.
The underactuated continuum mechanical arm according to claim 1, wherein a first support rod is connected to the moving platform, a second support rod is connected to the static platform, and the first support rod and the second support rod in each joint are connected through a spherical pair.
The underactuated continuum robotic arm according to claim 1, wherein a rope hole corresponding to the driven rope is provided on the moving platform of each joint, and the driven rope is connected to the corresponding rope hole.