Cable-driven bionic mechanical arm based on spherical cable-driven joints

Abstract

A cable-driven bionic mechanical arm based on spherical cable-driven joints comprises a shoulder joint, an elbow joint, a wrist joint and driving ropes distributed at all positions, wherein the shoulder joint, the elbow joint and the wrist joint are connected in sequence. The shoulder joint belongs to a spherical cable-driven joint, and a double-layer spherical hinge constrained by a single grommet and a three-degree-of-freedom rope parallel driving module are arranged in the shoulder joint; a single-degree-of-freedom rope parallel driving module is arranged in the elbow joint; the wrist joint belongs to a spherical cable-driven joint, and a spherical hinge and a three-degree-of-freedom rope parallel driving module are arranged in the wrist joint. According to the invention, concentrated arrangement of the driving units is realized, the joint structure is simple and stable, the motion range is large, and the robot has the advantages of high load-weight ratio and flexible motion, and is suitable for application scenes facing man-machine cooperation.

Description

Technical Field

[0001] The present application relates to the field of robotics technology, and in particular to a cable-driven bionic robotic arm based on a spherical cable-driven joint. Background Art

[0002] With the development of modern industry, robotic arms have been widely used in many fields. Bionic robotic arms, with their similar characteristics to human arms, have shown extremely high interaction and learning performance with people. They are favored in fields that require high interaction with people, such as medical treatment, human-computer interaction, and entertainment. Research on bionic robotic arms has high practical value and great development potential.

[0003] The human arm has a total of seven degrees of freedom, three at the shoulder joint, one at the elbow joint, one at the forearm joint, and two at the wrist joint. It has the characteristics of high degrees of freedom, low inertia, large workspace and high dynamic characteristics. The rope has the characteristics of high strength, low inertia and high flexibility. Rope drive has natural advantages in miniaturization, lightness, flexibility and precision. Due to the force transmission characteristics of the rope, the drive end can be arranged in almost any desired position. At the same time, the rope and the human tendon have high similarity in force transmission and motion transmission. Starting from the basic structure of the human upper limb, it is expected to achieve similarity between the drive mechanism and kinematics and humans, greatly improving the comprehensive performance of the bionic robotic arm.

[0004] In the existing cable-driven bionic robotic arm design, there are two design directions. One is to regard the rope as human muscles and imitate the human muscles to arrange the ropes. Since human muscles are mostly driven by direct pulling, this type of design usually uses a straight-pull cable configuration. The mechanical structure design of this configuration is simple, but due to the interference between the ropes and between the ropes and the mechanism, it is difficult for the joints to have a working space similar to that of the human body.

[0005] Another method regards the rope as a medium for remote transmission and designs the transmission structure to achieve rotational joints with the same degrees of freedom as the human body. This type of joint can achieve a working space similar to that of the human body, but usually has a complex mechanical structure and cable routing, and does not have similar kinematic laws and driving mechanisms as the human body.

[0006] Therefore, how to balance simple structural design, large workspace, and similarity of kinematics and drive mechanism with the human body is one of the research issues of humanoid robotic arms. Summary of the invention

[0007] In order to solve the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a cable-driven bionic manipulator based on a spherical cable-driven joint with a simple structure, a large working space, and kinematics and driving mechanism similar to those of the human body. It is noted that the deep muscles inside the human joint are mostly attached to the joint surface, so the spherical cable-driven joint is designed based on this mechanism. In the spherical cable-driven joint, the driving rope is wrapped around the surface of the sphere, and the rope relies on the inherent tension of the rope to adhere to the sphere and form a stable rope path, and is driven along the sphere.

[0008] In order to achieve the above object, the present invention adopts the following technical solution:

[0009] A cable-driven bionic manipulator based on a spherical cable-driven joint comprises a shoulder joint, an elbow joint, a wrist joint and driving ropes distributed at various positions which are connected in sequence; the shoulder joint belongs to the spherical cable-driven joint, and is internally provided with a double-layer ball joint constrained by a single cable ring and a three-degree-of-freedom rope parallel driving module; the elbow joint is internally provided with a single-degree-of-freedom rope parallel driving module; the wrist joint belongs to the spherical cable-driven joint, and is internally provided with a ball joint and a three-degree-of-freedom rope parallel driving module;

[0010] The spherical cable-driven joint has a driving rope wrapped around the surface of the sphere, and relies on the inherent tension of the driving rope to fit the spherical surface and form a stable rope path, thereby driving along the spherical surface;

[0011] The double-layer ball joint constrained by a single cable ring of the shoulder joint is composed of an outer base, a middle shell, an inner ball head and a closed rope ring. The closed rope ring passes through the cable holes on the outer base and the middle shell one by one, and is always covered on the surface of the middle shell when the middle shell performs two-degree-of-freedom deflection, forming a constrained structure;

[0012] The three-degree-of-freedom cable parallel drive module of the shoulder joint comprises a cable fixed to the middle shell and a cable fixed to the inner ball head; the cable fixed to the middle shell is led out from the cable outlet hole located on the outer base, arranged along the surface of the middle shell, and fixedly connected to the edge of the middle shell to drive the middle shell; the cable fixed to the inner ball head is led out from the cable outlet hole located on the outer base, passes through the cable through hole located on the middle shell along the surface of the middle shell and the inner ball head, is wound around and fixed on the shaft of the inner ball head, and drives the inner ball head;

[0013] The single-degree-of-freedom rope parallel drive module of the elbow joint comprises a movable pulley force-enhancing structure and a straight-pull cable drive module;

[0014] The movable pulley force-increasing structure is composed of a boom connecting rod, pulley 1, pulley 2, a movable pulley and a forearm base, wherein the boom connecting rod, pulley 1, pulley 2 and the forearm base are coaxial, and the movable pulley is located on the forearm base, and its central plane is tangent to the edges of pulley 1 and pulley 2;

[0015] The straight-pull cable drive module is composed of a boom connecting rod, a pulley three, a pulley four and a forearm base, wherein the pulley three is fixedly connected to the boom connecting rod, the pulley four is fixedly connected to the forearm base, and the pulleys three and four are located on the ventral side of the elbow joint; the forearm base elbow is driven by an elbow rope one and an elbow rope two, the elbow rope one is led out from the rope outlet hole located on the outer base, connected to the rope outlet hole of the boom connecting rod through a Bowden line, and successively bypasses the pulley one, the movable pulley and the pulley two located on the forearm base, and is fixedly connected to the boom connecting rod; the elbow rope two is led out from the rope outlet hole located on the outer base, connected to the rope outlet hole of the boom connecting rod through a Bowden line, bypasses the pulley three located on the boom connecting rod, and is fixedly connected to the pulley four located on the forearm base;

[0016] The ball joint of the wrist joint is composed of a wrist shell and a wrist ball head located in the wrist shell;

[0017] The three-degree-of-freedom rope parallel drive module of the wrist joint comprises a forearm connecting rod and four ropes fixed to the wrist ball head. The ropes are led out from the rope outlet holes located on the outer base, connected to the forearm connecting rod through Bowden cables, arranged along the surface of the wrist ball head, wound around and fixed on the shaft of the wrist ball head, and drive the wrist ball head. The driving principle is that when the rope on the same side is pulled, the wrist ball head is deflected, and when the rope on the opposite side is pulled, the wrist ball head is rotated.

[0018] The inner ball head is fixedly connected to the upper arm connecting rod, and the lower arm base is fixedly connected to the lower arm connecting rod, so that the shoulder joint, elbow joint and wrist joint are connected in sequence to form a bionic mechanical arm as a whole.

[0019] Preferably, four cable holes are evenly distributed on the edges of the outer base and the middle shell, and the closed rope rings are staggered through the eight cable holes one by one, and wrapped around the surface of the middle shell to form a constraint structure. When the wrap angles of the outer base and the middle shell are 45° and 103° respectively, the middle shell is constrained and has approximately two degrees of deflection freedom, expanding the deflection angle range of the inner ball joint.

[0020] Preferably, in the shoulder joint, there are four ropes fixed to the middle shell and four ropes fixed to the inner ball head, and the driving principle is: when the rope on the same side is pulled, the inner ball head is deflected, and the deflection angle is greater than 100°; when the rope on the opposite side is pulled, the inner ball head is rotated, and the rotation angle is greater than 360°. It can reach another posture from one posture with any trajectory in the working space.

[0021] Preferably, in the wrist joint, when the ipsilateral rope is pulled, the wrist ball head is deflected, and the deflection angle is greater than 50°; when the contralateral rope is pulled, the wrist ball head is rotated, and the rotation angle is greater than 360°, and it is possible to reach another posture from one posture with any trajectory in the working space.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] 1. Since the middle shell, the inner ball head and the wrist ball head simultaneously serve as the revolving pair in the structural parts and the rope guiding mechanism in the transmission parts, the mechanical design is reduced and the arm structure is simple;

[0024] 2. Since the ropes of the wrist and shoulder joints are wrapped on the spherical surface, the friction between the ropes and the spherical surface acts as a damper, the ropes are less likely to vibrate, and the rope path is more stable;

[0025] 3. Under the same driving torque, the rope wrapped around the spherical surface occupies a smaller volume than the straight cable, so the arm body volume is smaller.

[0026] 4. All joints of the robotic arm are remotely driven by ropes, and the arm does not have any drive, so it is light in weight and has good maneuverability.

[0027] In summary, the cable-driven bionic mechanical arm based on the spherical cable-driven joint of the present invention has a simple structure, small size, light weight, large load, good maneuverability, and a large working space. At the same time, the ropes arranged along the spherical surface are more stable and not easily interfered by the external environment. It is suitable for application scenarios facing human-machine collaboration. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention and / or the solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments and / or the prior art description. Obviously, the drawings described below are only some embodiments of the present invention.

[0029] Figure 1 It is a schematic diagram of the overall assembly structure of the cable-driven humanoid robot arm of the present invention;

[0030] Figure 2 It is a schematic diagram of the shoulder joint assembly structure of the present invention;

[0031] Figure 3 It is a schematic diagram of the elbow joint assembly structure of the present invention;

[0032] Figure 4 It is a schematic diagram of the wrist joint assembly structure of the present invention;

[0033] Description of Figure Numbers:

[0034]

[0035]

[0036] The implementation mode, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0037] The embodiments of the present application will be described in detail below in conjunction with the accompanying drawings, examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0038] like Figure 1 The cable-driven bionic mechanical arm based on a spherical cable-driven joint shown in the figure comprises a shoulder joint S, an elbow joint E and a wrist joint W which are fixedly connected in sequence.

[0039] The shoulder joint S comprises an outer base 1, a middle shell 4, an inner ball head 7 and a closed rope ring 2. The outer base 1, the middle shell 4 and the inner ball head 7 are in contact in a spherical sliding manner, and the sphere centers of the three coincide. The closed rope ring 2 passes through the cable holes located at the edges of the outer base 1 and the middle shell 4 one by one, and is coated on the surface of the middle shell 4 to form a constraint structure. Under the constraint of the closed rope ring 2, the middle shell 4 has two deflection degrees of freedom relative to the outer base 1, and the inner ball head 7 has three rotational degrees of freedom relative to the middle shell 2.

[0040] The middle shell 4 of the shoulder joint S is driven by middle rope 1 5, middle rope 2 8, middle rope 3 10 and middle rope 4 11, all of which are drawn from the outer base 1 and wrapped around the middle shell 4. The basic driving principle is that when the rope on one side is pulled, the middle shell 4 deflects in the corresponding direction.

[0041] The inner ball head 7 of the shoulder joint S is driven by inner rope 1 3, inner rope 2 6, inner rope 3 9 and inner rope 4 12, all of which are led out from the outer base 1, pass through the rope holes on the middle shell 4, and are wound around and covered on the surface of the inner ball head 7. The basic driving principle is that the inner ball head 7 deflects when the rope on the same side is pulled, and the inner ball head 7 spins when the rope on the opposite side is pulled.

[0042] The elbow joint E comprises an arm connecting rod 13, a pulley 15, a pulley 2 16, a pulley 3 14, a pulley 4 19, a movable pulley 18 and a forearm base 17, wherein the arm connecting rod 13, the pulley 15, the pulley 2 16 and the forearm base 17 are coaxial, the movable pulley 18 is located on the forearm base 17, and its central plane is tangent to the edges of the pulley 15 and the pulley 2 16; the pulley 3 14 is fixedly connected to the arm connecting rod 13, the pulley 4 19 is fixedly connected to the forearm base 17, and the pulley 3 14 and the pulley 4 19 are located on the ventral side of the elbow joint. The forearm base 17 has one degree of rotational freedom relative to the arm connecting rod 13.

[0043] The forearm base 17 of the elbow joint E is driven by the elbow rope 1 20 and the elbow rope 2 21. The elbow rope 1 20 is led out from the rope outlet hole of the boom link 13, passes through the pulley 1 15, the movable pulley 18 and the pulley 2 16 in sequence, and is fixed on the boom link 13; the elbow rope 2 21 is led out from the rope outlet hole of the boom link 13, passes through the pulley 3 14, and is fixed on the pulley 4 19. The basic driving principle is that when one side of the rope is pulled, the forearm base 17 rotates in the corresponding direction.

[0044] The wrist joint W includes a forearm link 26, a wrist housing 27 and a wrist ball head 28, wherein the wrist housing 27 is fixedly connected to the end of the forearm link 26, and the wrist ball head 28 and the wrist housing 27 are in contact in the form of spherical sliding. The wrist ball head 28 has three rotational degrees of freedom relative to the wrist housing 27.

[0045] The wrist ball head 28 of the wrist joint W is driven by wrist rope 1 22, wrist rope 2 23, wrist rope 3 24 and wrist rope 4 25, all of which are drawn out from the rope outlet holes of the forearm link 26, and are wound around and covered on the surface of the wrist ball head 28. The basic driving principle is that the wrist ball head 28 deflects when the rope on the same side is pulled, and the wrist ball head 28 spins when the rope on the opposite side is pulled.

[0046] The working process of the cable-driven bionic mechanical arm based on the spherical cable-driven joint of the present invention is: according to the kinematic geometric relationship, the middle layer rope 1 5, the middle layer rope 2 8, the middle layer rope 3 10, the middle layer rope 4 11, the inner layer rope 1 3, the inner layer rope 2 6, the inner layer rope 3 9 and the inner layer rope 4 12 are driven to rotate the shoulder joint S to the desired posture; the elbow rope 1 20 and the elbow rope 2 21 are driven to cause the elbow joint E to flex to the desired angle; the wrist rope 1 22, the wrist rope 2 23, the wrist rope 3 24 and the wrist rope 4 25 are driven to cause the wrist joint W to rotate to the desired posture.

[0047] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A cable-driven bionic manipulator based on a spherical cable-driven joint, characterized in that: It includes a shoulder joint, an elbow joint, a wrist joint connected in sequence, and driving ropes distributed at various positions; the shoulder joint is a spherical cable-driven joint, and is internally provided with a double-layer ball joint constrained by a single cable ring and a three-degree-of-freedom rope parallel driving module; the elbow joint is internally provided with a single-degree-of-freedom rope parallel driving module; the wrist joint is a spherical cable-driven joint, and is internally provided with a ball joint and a three-degree-of-freedom rope parallel driving module; The spherical cable-driven joint has a driving rope wrapped around the surface of the sphere, and relies on the inherent tension of the driving rope to fit the spherical surface and form a stable rope path, thereby driving along the spherical surface; The double-layer ball joint constrained by a single cable ring of the shoulder joint is composed of an outer base, a middle shell, an inner ball head and a closed rope ring. The closed rope ring passes through the cable holes on the outer base and the middle shell one by one, and is always covered on the surface of the middle shell when the middle shell performs two-degree-of-freedom deflection, forming a constrained structure; The three-degree-of-freedom cable parallel drive module of the shoulder joint comprises a cable fixed to the middle shell and a cable fixed to the inner ball head; the cable fixed to the middle shell is led out from the cable outlet hole located on the outer base, arranged along the surface of the middle shell, and fixedly connected to the edge of the middle shell to drive the middle shell; the cable fixed to the inner ball head is led out from the cable outlet hole located on the outer base, passes through the cable through hole located on the middle shell along the surface of the middle shell and the inner ball head, is wound around and fixed on the shaft of the inner ball head, and drives the inner ball head; The single-degree-of-freedom rope parallel drive module of the elbow joint comprises a movable pulley force-enhancing structure and a straight-pull cable drive module; The movable pulley force-increasing structure is composed of a boom connecting rod, a pulley 1, a pulley 2, a movable pulley and a forearm base, wherein the boom connecting rod, the pulley 1, the pulley 2 and the forearm base are coaxial, and the movable pulley is located on the forearm base, and its central plane is tangent to the pulley 1 and the pulley 2; The straight-pull cable drive module is composed of a boom connecting rod, a pulley three, a pulley four and a forearm base, wherein the pulley three is fixedly connected to the boom connecting rod, the pulley four is fixedly connected to the forearm base, and the pulleys three and four are located on the ventral side of the elbow; the forearm base elbow is driven by an elbow rope one and an elbow rope two, the elbow rope one is led out from the rope outlet hole located on the outer base, connected to the rope outlet hole of the boom connecting rod through a Bowden line, and successively bypasses the pulley one, the movable pulley and the pulley two located on the forearm base, and is fixedly connected to the boom connecting rod; the elbow rope two is led out from the rope outlet hole located on the outer base, connected to the rope outlet hole of the boom connecting rod through a Bowden line, bypasses the pulley three located on the boom connecting rod, and is fixedly connected to the pulley four located on the forearm base; The ball joint of the wrist joint is composed of a wrist shell and a wrist ball head located in the wrist shell; The three-degree-of-freedom cable parallel drive module of the wrist joint comprises a forearm connecting rod and four cables fixedly connected to the wrist ball head. The cables are led out from the cable outlet holes located on the outer base, connected to the forearm connecting rod through Bowden cables, arranged along the surface of the wrist ball head, wound around and fixed on the shaft of the wrist ball head, and drive the wrist ball head. The driving principle is that the wrist ball head deflects when the ipsilateral rope is pulled, and the wrist ball head rotates when the contralateral rope is pulled; The inner ball head is fixedly connected to the upper arm connecting rod, and the lower arm base is fixedly connected to the lower arm connecting rod, so that the shoulder joint, elbow joint and wrist joint are connected in sequence to form a bionic mechanical arm as a whole.

2. The cable-driven bionic mechanical arm based on a spherical cable-driven joint according to claim 1, characterized in that: There are four cable holes evenly distributed on the edges of the outer base and the middle shell. The closed rope rings are staggered through the eight cable holes one by one and wrapped around the surface of the middle shell to form a constraint structure. When the wrap angles of the outer base and the middle shell are 45° and 103° respectively, the middle shell is constrained and has approximately two deflection degrees of freedom, expanding the deflection angle range of the inner ball joint.

3. The cable-driven bionic mechanical arm based on a spherical cable-driven joint according to claim 1, characterized in that: In the shoulder joint, there are four ropes fixed to the middle shell and four ropes fixed to the inner ball head, and the driving principle is: when the rope on the same side is pulled, the inner ball head is deflected, and the deflection angle is greater than 100°; when the rope on the opposite side is pulled, the inner ball head is rotated, and the rotation angle is greater than 360°.

4. The cable-driven bionic mechanical arm based on a spherical cable-driven joint according to claim 1, characterized in that: In the wrist joint, when the ipsilateral rope is pulled, the wrist ball head is deflected, and the deflection angle is greater than 50°; when the contralateral rope is pulled, the wrist ball head is rotated, and the rotation angle is greater than 360°.

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