Cable-driven tensegrity continuous robotic arm

Abstract

This invention provides a rope-driven, tensioned, continuous robotic arm, belonging to the field of robotics technology. The robotic arm consists of several joint groups connected in series. Each joint group comprises several joints connected in series. Each joint includes a lower joint end, an upper joint end, a chuck, a push rod, a compression unit, a tension unit, and a ball joint. A tension unit and a compression unit are located between the lower and upper joint ends. A spring sleeve is fitted around the compression unit, and a chuck is mounted on the upper part of the spring sleeve. The chuck is connected to the ball joint via a push rod and a double-ended bolt. A ball joint sleeve is provided around the ball joint, which passes through a central through-hole at the upper end of the joint. Each joint group is equipped with a set of drive ropes. This invention, by constructing a three-level structure of joint-joint group-robotic arm, can achieve complex bending, compression, and coupled movements, mimicking various biomimetic movements of an elephant's trunk. It also possesses advantages such as good deformability and high structural rigidity, enabling independent movement of a single joint group and collaborative operation of multiple joint groups.

Description

Technical Field

[0001] This invention relates to the field of robotics, and more particularly to a rope-driven tensioned integral continuous robotic arm. Background Technology

[0002] The development of robotics technology is an important indicator of a country's scientific and technological innovation and high-end manufacturing level. In the face of confined, complex, and obstacle-ridden unstructured environments, continuous robotic arms, mimicking the structural morphology and functional principles of soft organs such as elephant trunks and octopus tentacles, possessing good flexibility and adaptability, have attracted increasing attention from researchers both domestically and internationally. However, existing structural design methods typically use soft materials as the main body, which, while offering good flexibility, have low structural stiffness and are difficult to withstand large loads. Other methods involve large-scale splicing of mechanical structures such as universal joints, but require a large number of joints to achieve good flexibility. How to construct a continuous robotic arm that combines functional flexibility and structural stiffness is one of the challenging problems in the field of robotic arms. Tensioned integral structures are a type of stable structure formed by the mutual balance of pre-compressed and pre-stretched components, possessing advantages such as deformability and good load-bearing capacity. Therefore, mimicking the elephant trunk's motion mode and based on the force principle of tensioned integral structures, this invention discloses a novel elephant trunk-inspired tensioned integral continuous robotic arm. Summary of the Invention

[0003] This invention provides a rope-driven, tensioned, continuous robotic arm. This robotic arm mimics the movement pattern of an elephant's trunk in nature, enabling various movements such as bending and compression. Structurally, the connection between rigid and flexible components gives the robotic arm both high flexibility and good rigidity. Functionally, the multi-joint group cooperative drive design allows the robotic arm to achieve both independent movement of single joint groups and collaborative operation of multiple joint groups, providing a new solution to the aforementioned problems.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0005] A rope-driven tensioned integral continuous robotic arm consists of several (generally no less than two) joint groups connected in series by drive ropes and connectors;

[0006] The joint assembly consists of several (generally no less than two) tensioned integral joints connected in series by connectors;

[0007] The tensioned integral joint includes an upper joint end, a lower joint end, a tension unit, and a compression unit. The upper and lower ends of the tension unit are respectively connected to the upper and lower joint ends. The lower part of the compression unit is connected to the lower joint end. The upper part of the compression unit is connected to a push rod. The push rod is connected to a ball joint by a double-ended bolt. The ball joint passes through the central through hole at the upper end of the joint and serves as a connector to the lower joint end of the next tensioned integral joint.

[0008] The drive rope is connected to the lower end of the joint, and the connection point of the drive rope and the connection point of the tension unit are located on the same radial direction at the lower end of the joint (correspondingly, the number of drive ropes connected to the lower end of the joint is the same as or an integer multiple of the number of springs in the tension unit).

[0009] The compression unit is a compression spring with a stiffness 10 to 30 times that of the tension unit, and the compression spring is located in a spring sleeve with circumferentially distributed rectangular grooves.

[0010] The top of the spring sleeve is provided with a chuck, which consists of two semi-circular discs and is connected to the spring sleeve by bolts to prevent the compressed spring from slipping out of the spring sleeve.

[0011] The push rod is designed with a fan blade and a spring sleeve assembly. The compression and recovery of the compressed unit are achieved by sliding the push rod in the rectangular groove.

[0012] The tension unit consists of four tension springs.

[0013] The upper and lower ends of the joint are two disc-shaped structures, and hooks are provided on the opposite sides of the two disc-shaped structures. The two ends of the tension spring are respectively connected to the hooks of the two disc-shaped structures.

[0014] The ball joint is connected to an external ball joint sleeve by bolts.

[0015] In the above structure, the sleeve height needs to be adapted to the free height of the pressure unit to avoid tension problems in the pressure unit; the center of the ball joint is higher than the hook connection point at the upper end of the joint to avoid structural instability.

[0016] The tensioning integral joint is driven by the same set of circumferentially distributed drive ropes, forming a joint group;

[0017] No fewer than two joint groups are connected in series, each joint group is driven by a different set of drive ropes to form a robotic arm, wherein the drive rope of the latter joint group passes through all the preceding joint groups.

[0018] The upper and lower ends of the joint, the spring sleeve, the push rod, the chuck, and the ball joint sleeve are made of lightweight, high-buffering energy-absorbing materials, including aluminum alloy, stainless steel, and epoxy resin.

[0019] The tension and compression units are made of materials or structures that have a certain tensile / compressive stiffness but cannot withstand pressure / tension, including elastic ropes, shape memory alloys or springs; the ball joint can be a structure with omnidirectional rotation function; all of the above components can be replaced according to requirements.

[0020] In this robotic arm, the greater the stiffness difference between the tension and compression units, the smaller the compressive deformation of the structural coupling when the joint undergoes bending deformation. However, an increased stiffness difference also requires a larger external load to induce compressive deformation in the robotic arm. Preferably, the stiffness of the compression spring is 10 to 30 times that of the tension spring.

[0021] The above technical solution has at least the following advantages compared with the existing technology:

[0022] The above scheme utilizes the principle of tension-compression balance, which gives the joint both flexibility and sufficient structural rigidity. To mimic the basic movements of an elephant's trunk—bending, compression, and torsion—a three-tiered structure of joint-joint group-robotic arm is constructed, enabling the robotic arm to perform complex bending, compression, and coupled movements.

[0023] When no external drive is applied, the robotic arm can maintain its initial state due to the prestress in its structure. When an external load is applied, the drive rope contracts, causing the robotic arm to move. Depending on the type of drive rope, the robotic arm can produce different motion patterns. Since the drive rope is continuous, the deformation of each joint can be considered uniform.

[0024] The following are some drive schemes and robotic arm variations: For driving only any one joint group: A single drive rope under tension can achieve unidirectional bending of that joint group; an adjacent drive rope under tension, depending on the load on the two drive ropes, can cause the joint group to bend within the space formed by the two drive ropes; tension on the opposite side / all drive ropes can achieve overall compression of all joint groups affected by the drive rope of that joint group. For driving any two adjacent joint groups: A single drive rope for each of the two joint groups under tension, depending on the amount of contraction, can achieve unidirectional variable curvature bending of the two joint groups; tension on a single drive rope of any joint group, and tension on the opposite single drive rope of another adjacent joint group, can achieve S-shaped bending of the two joint groups. Extending these drive schemes to a robotic arm allows for both independent movement of a single joint group and collaborative operation of multiple joint groups.

[0025] The above functions are all related to the number of joints connected in series and the setting of drive ropes. As the number of joints increases and the drive ropes are different, the robotic arm can combine complex motion patterns. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the overall structure of a rope-driven tensioned continuous robotic arm according to the present invention;

[0028] Figure 2 for Figure 1 A magnified view of a single joint in section A;

[0029] Figure 3 This is a schematic diagram of the bending configuration of the robotic arm under the contraction of a single rope of the present invention.

[0030] Figure 4 This is a schematic diagram of the S-shaped configuration of the robotic arm of the present invention under the contraction of multiple ropes.

[0031] The annotations in the attached figures are explained as follows:

[0032] 1-Lower end of joint; 2-Spring sleeve; 3-Chuck; 4-Push rod; 5-Double-ended bolt; 6-Spherical joint; 7-Compression unit; 8-Tension unit; 9-Spherical joint sleeve; 10-Upper end of joint; 11-Drive rope for the first joint group; 12-Drive rope for the second joint group. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0034] It should be noted that the terms "up", "down", "left", "right", "front", and "back" used in this invention are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0035] This invention provides a rope-driven, tensioned, continuous robotic arm. For example... Figure 1 As shown, the robotic arm consists of several joint groups connected in series via drive ropes and connectors;

[0036] The joint assembly is composed of several tension integral joints connected in series by connectors;

[0037] like Figure 2 The tensioning integral joint includes an upper joint end 10, a lower joint end 1, a tension unit 8, and a compression unit 7. The upper and lower ends of the tension unit 8 are respectively connected to the upper joint end 10 and the lower joint end 1. The lower part of the compression unit 7 is connected to the lower joint end 1, and the upper part of the compression unit 7 is connected to a push rod 4. The push rod 4 is connected to a ball joint 6 through a double-ended bolt 5. The ball joint 6 passes through the central through hole of the upper joint end 10 and serves as a connector to the lower joint end 1 of the next tensioning integral joint.

[0038] The drive rope is connected to the lower end of the joint, and the connection point of the drive rope and the connection point of the tension unit are located on the same radial direction at the lower end of the joint.

[0039] The compression unit is a compression spring with a stiffness 10 to 30 times that of the tension unit, and the compression spring is located in a spring sleeve 2 with circumferentially distributed rectangular grooves.

[0040] The top of the spring sleeve 2 is provided with a chuck 3, which consists of two semi-circular discs and is connected to the spring sleeve by bolts.

[0041] The push rod 4 is designed with a fan blade and a spring sleeve assembly. The compression and recovery of the compressed unit are achieved by sliding the push rod in the rectangular groove.

[0042] The tension unit 8 consists of four tension springs.

[0043] The upper and lower ends of the joint are two disc-shaped structures, and hooks are provided on the opposite sides of the two disc-shaped structures. The two ends of the tension spring are respectively connected to the hooks of the two disc-shaped structures.

[0044] The ball joint 6 is connected to the external ball joint sleeve 9 by bolts.

[0045] The center of the ball joint is higher than the hook-and-loop connection point at the upper end of the joint.

[0046] The tensioning integral joint is driven by the same set of circumferentially distributed drive ropes, forming a joint group;

[0047] No fewer than two joint groups are connected in series, each joint group is driven by a different set of drive ropes to form a robotic arm, wherein the drive rope of the latter joint group passes through all the preceding joint groups.

[0048] In specific design, such as Figure 1As shown, the robotic arm is in its initial state. Its structure consists of six interconnected tensioned integral joints, each with identical structural dimensions and mechanical properties. The robotic arm has eight drive cables. Four of these cables are connected at one end to the hook at the lower end of the third joint, evenly distributed circumferentially, and at the other end to a motor. The other four cables are connected at one end to the hook at the lower end of the sixth joint, also evenly distributed circumferentially, and at the other end to a motor.

[0049] Based on the configuration of the robotic arm's drive ropes, the robotic arm can be divided into two joint groups. The first three joints are collectively referred to as the first joint group, and the latter three joints are collectively referred to as the second joint group. The drive rope 12 of the second joint group passes through the first joint group. By controlling the contraction of the eight drive ropes (drive rope 11 of the first joint group and drive rope 12 of the second joint group) via a motor, the joint groups coordinate with each other, allowing the robotic arm to exhibit various motion modes.

[0050] like Figure 3 As shown, in this embodiment, the driving scheme involves only a single drive rope of the second joint group of the robotic arm being stretched. The working mechanism and deformation effect of the robotic arm are as follows: any motor of the second joint group receives a pulse signal from the host computer, and the drive rope connected to the motor generates a corresponding contraction. At the same time, according to the kinematic model, the other motors of the second joint group receive pulse signals, and the corresponding other drive ropes generate a stretch. At this time, the state of the robotic arm changes from the initial state to the bending state, the second joint group undergoes bending deformation, and the first joint group remains unchanged.

[0051] like Figure 4 As shown, the driving scheme in this example is an S-shaped retraction of the robotic arm. Specifically, a single drive cable of the second joint group is under tension, and a corresponding single drive cable of the first joint group is also under tension. The working mechanism and deformation effect of the robotic arm are as follows: Any motor in the second joint group receives a pulse signal from the host computer, and the drive cable connected to the motor generates a corresponding contraction amount. According to the kinematic model, the remaining motors in the second joint group receive pulse signals, and the corresponding remaining drive cables generate extension amounts. The working mechanism is consistent with only the single drive cable of the second joint group being under tension. Simultaneously, the corresponding single drive cable of the first joint group is under tension, and according to the kinematic model, the remaining drive cables generate extension amounts. At this point, the robotic arm's state changes from the initial state to an S-shaped bending state.

[0052] In the above driving scheme, all driving ropes should receive signals simultaneously.

[0053] The following points need to be explained:

[0054] (1) The accompanying drawings of the embodiments of the present invention only involve the structures involved in the embodiments of the present invention. Other structures can refer to the general design.

[0055] (2) Where there is no conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other to obtain new embodiments.

[0056] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. The scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A rope-driven, tensioned, continuous robotic arm, characterized in that, It consists of several joint groups connected in series via drive ropes and connectors; The joint assembly is composed of several tension integral joints connected in series by connectors; The tensioned integral joint includes an upper joint end, a lower joint end, a tension unit, and a compression unit. The upper and lower ends of the tension unit are respectively connected to the upper and lower joint ends. The lower part of the compression unit is connected to the lower joint end. The upper part of the compression unit is connected to a push rod. The push rod is connected to a ball joint by a double-ended bolt. The ball joint passes through the central through hole at the upper end of the joint and serves as a connector to the lower joint end of the next tensioned integral joint.

2. The rope-driven tensioned integral continuous robotic arm according to claim 1, characterized in that, The drive rope is connected to the lower end of the joint, and the connection point of the drive rope and the connection point of the tension unit are located on the same radial direction at the lower end of the joint.

3. The rope-driven tensioned integral continuous robotic arm according to claim 1, characterized in that, The compression unit is a compression spring with a stiffness 10 to 30 times that of the tension unit, and the compression spring is located in a spring sleeve with circumferentially distributed rectangular grooves. The spring sleeve is provided with a chuck at the top, and the chuck is composed of two semi-circular discs, which are connected to the spring sleeve by bolts. The push rod is designed with a fan blade and a spring sleeve assembly. The compression and recovery of the compressed unit are achieved by sliding the push rod in the rectangular groove.

4. The rope-driven tensioned integral continuous robotic arm according to claim 1, characterized in that, The tension unit consists of four tension springs. The upper and lower ends of the joint are two disc-shaped structures, and hooks are provided on the opposite sides of the two disc-shaped structures. The two ends of the tension spring are respectively connected to the hooks of the two disc-shaped structures.

5. The rope-driven tensioned integral continuous robotic arm according to claim 3, characterized in that, The ball joint is connected to an external ball joint sleeve by bolts.

6. The rope-driven tensioned integral continuous robotic arm according to claim 4, characterized in that, The center of the ball joint is higher than the hook-and-loop connection point at the upper end of the joint.

7. The rope-driven tensioned integral continuous robotic arm according to claim 1, characterized in that, The tensioning integral joint is driven by the same set of circumferentially distributed drive ropes, forming a joint group; The robotic arm consists of at least two joint groups connected in series, each driven by a different set of drive ropes, with the drive rope of the later joint group passing through all the preceding joint groups.

8. The rope-driven tensioned integral continuous robotic arm according to claim 5, characterized in that, The upper end of the joint, the lower end of the joint, the spring sleeve, the push rod, the chuck, and the ball joint sleeve are made of lightweight, high-buffering energy-absorbing materials, specifically one or more of aluminum alloy, stainless steel, and epoxy resin.

9. The rope-driven tensioned integral continuous robotic arm according to claim 1, characterized in that, The tension unit and compression unit are made of elastic rope, shape memory alloy or spring.

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