An underwater elephant trunk rope continuous type mechanical arm and a control method thereof

Abstract

This invention relates to the field of underwater robots and biomimetic robotic arms, and particularly to an underwater elephant trunk-like continuous robotic arm and its control method, comprising a drive box, a continuous robotic arm body, a drive rope, and an end effector; the continuous robotic arm body includes at least two continuous joint segments connected sequentially along the axial direction, each continuous joint segment including a base disk, an end disk, a plurality of intermediate support disks disposed between the base disk and the end disk, and a central support structure; by adopting a three-segment elephant trunk-like variable diameter continuous structure, the robotic arm has good compliant bending ability, spatial passage ability, and adaptability to complex environments; by setting anti-torsion holes on the disks and inserting anti-torsion rods to form an anti-torsion skeleton distributed along the axial direction of the joint segments, the torsional stiffness of the continuous joint segments around the axis can be effectively improved, bending-accompanied torsion can be reduced, and end-effector posture stability and repeatability can be improved.

Description

Technical Field

[0001] This application relates to the field of underwater robots and biomimetic robotic arms, and in particular to an underwater continuous robotic arm that mimics an elephant trunk rope and its control method. Background Technology

[0002] With the increasing demand for marine resource development and underwater operations, traditional rigid robotic arms are clearly insufficient for underwater tasks in confined spaces due to their large size, high mass, limited degrees of freedom, and weak ability to navigate complex and narrow environments. Compared with traditional rigid robotic arms, continuous robotic arms have advantages such as more degrees of freedom, better compliance, more flexible movement, and the ability to navigate around obstacles, making them more suitable for biomimetic operations in complex environments.

[0003] Rope-driven continuous robotic arms achieve bending and rotation of joint segments by retracting and extending the drive rope, combining advantages such as small size, light weight, and ease of remote actuation. However, existing underwater rope-driven continuous robotic arms still have the following problems in practical applications: On the one hand, under underwater fluid disturbances and the coordinated actuation of multiple ropes, the continuous joint segments of the robotic arm are prone to bending and twisting, resulting in end-effector attitude deviation, decreased repeatability, and insufficient motion consistency; on the other hand, the robotic arm often needs to maintain good compliant passage capability while also possessing a certain degree of stability and external protection capability in different tasks. Based on this, it is necessary to propose an underwater continuous robotic arm that combines an elephant trunk-like continuous configuration, rope-driven compliant characteristics, torsional resistance, and external constraint capability. Summary of the Invention

[0004] To address the problems existing in the background art, this invention proposes an underwater elephant trunk rope-like continuous robotic arm and its control method.

[0005] The underwater elephant trunk rope-inspired continuous robotic arm and its control method provided in this application adopt the following technical solution: An underwater continuous robotic arm with an elephant trunk rope design includes a drive unit, a continuous robotic arm body, a drive rope, and an end effector. The continuous robotic arm body includes at least two continuous joint segments connected sequentially along the axial direction. Each continuous joint segment includes a base disk, an end disk, a plurality of intermediate support disks disposed between the base disk and the end disk, and a central support structure. The drive box is located at the near end of the continuous robotic arm body. The drive box contains a drive device and a drive rope guide mechanism. After being guided by the guide mechanism, the drive rope passes through the wire hole on each disc and is connected to the corresponding continuous joint segment to drive the corresponding continuous joint segment to produce bending and / or rotational motion. Each of the continuous joint segments has anti-torsion holes on its disk, and each continuous joint segment has at least two anti-torsion rods that pass through the anti-torsion holes. The anti-torsion rods extend along the axial direction of the continuous joint segment and are spaced apart along the circumferential direction to form an anti-torsion skeleton for the continuous joint segment, which is used to limit the torsion of the continuous joint segment around its own axis. The continuous robotic arm body is provided with a flexible sleeve on its outside, and at least one set of clamping members are provided on the outside of the flexible sleeve for applying circumferential constraints to the continuous joint segments.

[0006] Furthermore, the continuous robotic arm body includes a first continuous joint segment, a second continuous joint segment, and a third continuous joint segment connected sequentially along the axial direction, and the three continuous joint segments form a trunk-like variable diameter structure that is narrower at the front and wider at the back along the length direction of the robotic arm.

[0007] Furthermore, each continuous joint segment is provided with three anti-torsion bars, which extend along the axial direction of the continuous joint segment and are evenly spaced along the circumferential direction.

[0008] Furthermore, the anti-torsion hole is located in the bisector direction of the angle between adjacent drive rope passage holes within the same continuous joint segment.

[0009] Furthermore, each of the continuous joint segments is provided with three drive ropes, and the three drive ropes in the same continuous joint segment are arranged at intervals along the circumferential direction.

[0010] Furthermore, the central support structure is a central support rod that can be elastically deformed.

[0011] Furthermore, the flexible sleeve has a segmented structure, with each sleeve segment corresponding to a continuous joint segment, and the outer diameter of the sleeve gradually decreases along the length of the robotic arm.

[0012] Furthermore, the fastening element is a strap, clamp, or binding rope, and the fastening elements are arranged at intervals along the axial direction of the robotic arm, with the size of each fastening element gradually decreasing along the length of the robotic arm.

[0013] Furthermore, the diameter of the disk in each continuous joint segment decreases sequentially from the proximal end to the distal end along the length of the robotic arm.

[0014] This application also provides a control method for an underwater elephant trunk rope-inspired continuous robotic arm, the control method comprising the following steps: S1. Establish the mapping relationship between the drive space, joint space and operation space, and solve the length change of the drive rope of each continuous joint segment according to the target end pose. S2. Control the drive device to extend and retract the corresponding drive rope according to the length change, so as to realize the bending motion of the continuous joint segment; S3. During the bending motion, the torsion of the continuous joint segments is restricted by the anti-torsion skeleton, and the posture stability of the robotic arm in the underwater environment is improved by the flexible sleeve and the clamping member.

[0015] Beneficial effects Compared with the prior art, the present invention provides an underwater elephant trunk rope-inspired continuous robotic arm and its control method, which has the following beneficial effects: 1. In this invention, a three-segment elephant trunk-like variable diameter continuous structure is adopted, which gives the robotic arm good flexibility, spatial mobility and adaptability to complex environments.

[0016] 2. In this invention, the bottom-centralized drive and double pulley reversing structure can reduce the size and mass of the robotic arm body, and is conducive to improving the overall compactness of the layout and the guiding efficiency of the drive rope.

[0017] 3. In this invention, by setting anti-torsion holes on the disc and inserting anti-torsion rods, an anti-torsion skeleton distributed along the joint segment axis is formed, which can effectively improve the axial torsional stiffness of the continuous joint segment, reduce bending accompanied by torsion, and improve end-effector posture stability and repeatability.

[0018] 4. In this invention, by setting a flexible sleeve on the outside of the robotic arm, the robotic arm's ability to isolate and protect itself from the external underwater environment can be improved, and a continuous force-bearing interface can be provided for the peripheral constraints.

[0019] 5. In this invention, by setting a clamping element on the outside of the flexible sleeve, the degree of local circumferential constraint of the continuous joint segment can be adjusted according to the task requirements, thereby taking into account both the compliant passage capability and stable operation capability of the robotic arm.

[0020] 6. In this invention, by coordinating the anti-torsion skeleton with the flexible sleeve and the fastening element, a composite stable structure with both internal anti-torsion reinforcement and external circumferential constraint can be formed, thereby improving the operational reliability of the robotic arm in complex underwater environments. Attached Figure Description

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0022] Figure 1 This is a three-dimensional structural diagram of this application.

[0023] Figure 2 This is a three-dimensional structural diagram of the drive box and the continuous robotic arm body of this application.

[0024] Figure 3 This is a three-dimensional structural diagram of the continuous joint segment of this application.

[0025] Figure 4 This is a three-dimensional structural diagram of the drive box of this application.

[0026] Figure 5 This is a cross-sectional structural diagram of the drive box of this application.

[0027] Explanation of reference numerals in the attached drawings: 1. Drive box; 2. Continuous robotic arm body; 3. First continuous joint segment; 4. Second continuous joint segment; 5. Third continuous joint segment; 6. Drive rope; 7. End effector; 8. Base disk; 9. End disk; 10. Intermediate support disk; 101. Anti-torsion hole; 11. Central support structure; 12. Anti-torsion bar; 13. Flexible sleeve; 14. Fastening element; 15. Drive motor; 16. Guide wheel; 17. Winding wheel; 18. Top plate; 19. Intermediate plate; 20. Base plate; 21. Bolt. Detailed Implementation

[0028] 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 embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1 like Figures 1 to 5 As shown, this embodiment provides an underwater elephant trunk-like rope-driven continuous robotic arm, including a drive box 1, a continuous robotic arm body 2, a drive rope 6, an end effector 7, and a control system. The control system is electrically connected to the drive box 1 and the end effector 7, and the control system can adjust the angle of the end effector 7 through the continuous robotic arm body 2.

[0030] The continuous robotic arm body 2 includes at least two continuous joint segments connected sequentially along the axial direction. As a preferred embodiment, such as... Figure 1 As shown, the continuous robotic arm body 2 specifically includes a first continuous joint segment 3, a second continuous joint segment 4, and a third continuous joint segment 5 connected sequentially along the axial direction. The three continuous joint segments form a trunk-like variable diameter structure that is narrower at the front and wider at the back along the length direction of the robotic arm. In this embodiment, the disc diameter of each continuous joint segment decreases sequentially from the proximal end (drive box 1 side) to the distal end (end actuator 7 side) along the length direction of the robotic arm to form a trunk-like tapered shape.

[0031] Each continuous joint segment includes a base disk 8, an end disk 9, a plurality of intermediate support disks 10 disposed between the base disk and the end disk, and a central support structure 11. The central support structure 11 is an elastically deformable central support rod, such as a slender rod made of spring steel, nickel-titanium alloy or superelastic polymer material, used to provide axial support for each joint segment and allow it to bend.

[0032] like Figures 4-5 As shown, the drive box 1 is located at the near end (i.e., the bottom or root) of the continuous robotic arm body 2. The drive box 1 is equipped with a drive device and a drive rope guide mechanism. The drive device includes a base plate 20, a middle plate 19, a top plate 18, a drive motor 15, and bolts 21. The base plate 20, the middle plate 19, and the top plate 18 are arranged sequentially. The base plate 20 and the middle plate 19 are connected by bolts 21 to form a receiving cavity. The guide mechanism is located inside the receiving cavity and is fixedly installed in the middle of the base plate 20. Motor seats are evenly installed on the side of the middle plate 19 near the top plate 18. Motor holes are evenly opened on the top plate 18. The drive motor 15 is installed on the motor holes. The top end of the drive motor 15 extends into the receiving cavity through the motor seat and is connected to the guide mechanism.

[0033] like Figure 5 As shown, the guiding mechanism includes multiple guide wheels 16 and winding wheels 17. The number of guide wheels 16 and winding wheels 17 corresponds to the number of drive motors 15. The guide wheels 16 are installed in the middle of the base plate 20, and the winding wheels 17 are installed on the outer side of the base plate 20. The output end of the drive motor 15 is connected to the winding wheels 17. After being guided by the guide wheels 16 and winding wheels 17, the drive rope 6 passes through the corresponding guide holes on each disc and is connected to the end disc 9 of the corresponding continuous joint segment. By controlling the drive device to retract and extend the drive rope 6, the corresponding continuous joint segment can be driven to produce bending or rotational movements.

[0034] Preferably, each continuous joint segment is provided with three drive ropes 6. The three drive ropes in the same continuous joint segment are arranged at 120° intervals along the circumferential direction to realize the bending motion and combined bending of the joint segment in two orthogonal directions. The drive ropes 6 between different continuous joint segments can be staggered at a certain angle along the circumferential direction to avoid motion interference. The drive ropes 6 are preferably made of super-elastic steel wire rope, polymer fiber rope (such as Dyneema rope) or shape memory alloy wire with a diameter of 0.3mm-1.0mm to take into account both high strength and low bending resistance.

[0035] Example 2 like Figures 2-5 As shown, this embodiment, based on embodiment one, further provides an anti-torsion frame and external constraint structure to improve the stability of the robotic arm around the axis.

[0036] Anti-torsion holes 101 are provided on the disks of each continuous joint segment, and at least two anti-torsion rods 12 are provided in each continuous joint segment, passing through the anti-torsion holes 101. In this embodiment, three anti-torsion rods 12 are preferred. The anti-torsion rods 12 extend along the axial direction of the continuous joint segment and are evenly distributed along the circumferential direction to form an anti-torsion skeleton of the continuous joint segment. The anti-torsion skeleton is used to limit the torsion of the continuous joint segment about its own axis and improve the posture stability during bending.

[0037] To avoid motion interference between the anti-torsion bar 12 and the drive rope 6, the anti-torsion hole 101 is preferably located on the bisector of the angle between adjacent drive rope passage holes in the same continuous joint segment. For example, when each joint segment is provided with three drive ropes 6, the three anti-torsion bars 12 are respectively located at the mid-angle position between each pair of adjacent drive ropes, that is, arranged at 60° intervals on the bisector of the angle between the drive ropes, and the whole is still distributed at 120° intervals.

[0038] Furthermore, a flexible sleeve 13 is provided on the outside of the continuous robotic arm body 2. The flexible sleeve 13 can be made of flexible polymer materials such as polyurethane elastomer, silicone rubber or thermoplastic elastomer. The flexible sleeve 13 is used to provide external isolation, protection and a continuous peripheral force interface for the robotic arm body.

[0039] At least one set of clamping members 14 are provided on the outer side of the flexible sleeve 13. The clamping members 14 are used to apply circumferential constraints to the continuous joint segment, thereby improving the local equivalent stiffness and damping of the joint segment. The clamping members 14 can be annular tightening members such as straps, clamps, cable ties, or binding ropes. The clamping members 14 are arranged at intervals along the axial direction of the robotic arm, and the number of them can be one, two, or more. In the tightened state, the clamping members 14 transmit circumferential clamping force inward through the flexible sleeve 13. In the relaxed state, the robotic arm can still maintain a high degree of compliance.

[0040] As a preferred structure in this embodiment, the flexible sleeve 13 is a segmented structure, with each sleeve segment corresponding to a continuous joint segment, and the outer diameter of each sleeve segment gradually decreases along the length of the robotic arm to adapt to the elephant trunk-like variable diameter structure; correspondingly, the fastening member 14 is set in multiple groups, with each group corresponding to a sleeve segment, and the size of each fastening member 14 also gradually decreases along the length of the robotic arm.

[0041] Through the above structure, the anti-torsion skeleton, the flexible sleeve 13 and the clamping member 14 together form a synergistic stabilizing structure with internal anti-torsion reinforcement and external circumferential constraint, which improves the attitude stability and motion consistency of the robotic arm in the underwater fluid disturbance environment.

[0042] Example 3 This embodiment provides another preferred variable diameter structural parameter. The continuous robotic arm body 2 includes a first continuous joint segment 3, a second continuous joint segment 4, and a third continuous joint segment 5. The length of each continuous joint segment is 200mm, and the total length of the whole machine is 600mm. Each continuous joint segment is provided with 7 disks, namely 1 base disk 8, 1 end disk 9, and 5 intermediate support disks 10. A total of 21 disks are provided in the three continuous joint segments.

[0043] The base disc of the first continuous joint segment 3 has a diameter of 56 mm, the end disc of the third continuous joint segment 5 has a diameter of 38 mm, and the diameter of each disc in the middle decreases by 1 mm from bottom to top, forming a uniformly tapered shape resembling an elephant trunk.

[0044] In the first continuous joint segment 3, the second continuous joint segment 4, and the third continuous joint segment 5, the radius of the distance between the wire hole of the drive rope 6 and the center of the disk is 21mm, 17mm, and 14mm, respectively; the circumferential radius of the anti-torsion bar 12 is 23mm, 19mm, and 15mm, respectively; the diameter of the anti-torsion hole is 2.4mm, 2.0mm, and 1.6mm, respectively; the diameter of the anti-torsion bar is 2.1mm, 1.7mm, and 1.3mm, respectively; the diameter of the central support bar is 4.5mm, 4.0mm, and 3.5mm, respectively; and the drive rope 6 is made of 0.5mm diameter super-elastic steel wire rope.

[0045] The flexible sleeve 13 is divided into three sections, each 200mm in length. The first section has an inner diameter of 37mm at the bottom and 29mm at the top. The second section has an inner diameter of 29mm at the bottom and 26mm at the top. The third section has an inner diameter of 27mm at the bottom and 24mm at the top. The sleeve wall thickness is 1mm, and the material is polyurethane elastomer. There is an assembly gap between each sleeve section and the corresponding continuous joint section. Three sets of fastening members 14 are provided, each corresponding to one of the three continuous joint sections. Each set of fastening members 14 is installed 40mm from the left end of the corresponding sleeve section. The width and wall thickness of the fastening members 14 gradually decrease along the length of the robotic arm.

[0046] Example 4 This embodiment provides a control method for an underwater elephant trunk-like rope-driven continuous robotic arm based on the above embodiments. The method includes the following steps: S1. Establish mapping relationships and solve driving variables Establish a mapping relationship between the drive space, joint space, and operation space. Specifically, based on the geometric parameters of the robotic arm, the routing of the drive rope, and the kinematic model of each continuous joint segment, establish a forward and inverse mapping from the change in length of the drive rope to the bending angle and bending plane azimuth of the joint segment (joint space), and then to the position and posture of the end effector (operation space). Based on the target end effector pose, solve the bending angle required for each continuous joint segment through inverse kinematics, and then solve the length change (i.e., extension / retraction) required for each drive rope 6.

[0047] S2, Execution Drive Control Based on the calculated changes in the length of each drive rope, the drive device in the drive box 1 is controlled to precisely wind up and down the corresponding drive rope 6. By controlling the different wind up and down amounts of the three drive ropes in the same joint segment, continuous bending motion of the joint segment in any bending plane is achieved. By controlling the bending of multiple joint segments sequentially or in coordination, a large-scale spatial movement of the entire robotic arm is achieved.

[0048] S3, Enhanced Attitude Stability During the bending motion of each joint segment, the anti-torsion skeleton formed by the anti-torsion rods 12 passing through the anti-torsion holes 101 of each disc passively restricts the accompanying torsion of each continuous joint segment around its own axis. At the same time, the flexible sleeve 13 and the fastening member 14 sleeved on the outside of the robotic arm apply additional circumferential compression constraints to the outer periphery of the robotic arm, thereby improving the equivalent stiffness and anti-disturbance capability of the joint segments. Thus, the above-mentioned internal and external structures work together to improve the attitude stability and end-effector positioning accuracy of the robotic arm in complex environments such as underwater fluid disturbances and wave impacts.

[0049] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. An underwater elephant trunk rope continuous type robot arm, characterized by, It includes a drive box (1), a continuous robotic arm body (2), a drive rope (6), and an end effector (7); The continuous robotic arm body (2) includes at least two continuous joint segments connected sequentially along the axial direction. Each continuous joint segment includes a base disk (8), an end disk (9), a plurality of intermediate support disks (10) disposed between the base disk and the end disk, and a central support structure (11). The drive box (1) is located at the near end of the continuous robotic arm body (2). The drive box is equipped with a drive device and a drive rope guide mechanism. The drive rope (6) is guided by the guide mechanism and passes through the wire hole on each disc and is connected to the corresponding continuous joint segment to drive the corresponding continuous joint segment to produce bending and / or rotational motion. Each of the continuous joint segments is provided with an anti-torsion hole (101) on its disk. Each continuous joint segment is provided with at least two anti-torsion rods (12) that pass through the anti-torsion hole (101). The anti-torsion rods (12) extend along the axial direction of the continuous joint segment and are distributed at intervals along the circumferential direction to form an anti-torsion skeleton of the continuous joint segment, which is used to limit the torsion of the continuous joint segment about its own axis. The continuous robotic arm body (2) is provided with a flexible sleeve (13) on the outside, and at least one set of fastening members (14) are provided on the outside of the flexible sleeve (13) for applying circumferential constraints to the continuous joint segment.

2. The underwater elephant-trunk-imitating-rope continuous type mechanical arm according to claim 1, characterized in that: The continuous robotic arm body (2) includes a first continuous joint segment (3), a second continuous joint segment (4) and a third continuous joint segment (5) connected sequentially along the axial direction, and the three continuous joint segments form a trunk-like variable diameter structure that is narrow at the front and wide at the back along the length direction of the robotic arm.

3. The underwater elephant-trunk-imitating-rope continuous type mechanical arm according to claim 2, characterized in that: Each continuous joint segment is provided with three anti-torsion bars (12), which extend along the axial direction of the continuous joint segment and are evenly distributed along the circumferential direction.

4. The underwater elephant trunk rope-like continuous robotic arm according to claim 1, characterized in that: The anti-torsion hole (101) is located in the bisector direction between adjacent drive rope passage holes within the same continuous joint segment.

5. The underwater elephant trunk rope-like continuous robotic arm according to claim 1, characterized in that: Each of the continuous joint segments is provided with three drive ropes (6), and the three drive ropes in the same continuous joint segment are arranged at intervals along the circumferential direction.

6. The underwater elephant trunk rope-like continuous robotic arm according to claim 1, characterized in that: The central support structure (11) is a central support rod that can be elastically deformed.

7. The underwater elephant trunk rope-like continuous robotic arm according to claim 1, characterized in that: The flexible sleeve (13) has a segmented structure, with each sleeve segment corresponding to a continuous joint segment, and the outer diameter of the sleeve gradually decreases along the length of the robotic arm.

8. The underwater elephant trunk rope-like continuous robotic arm according to claim 1, characterized in that: The fastening element (14) is a strap, clamp or binding rope. The fastening elements (14) are arranged at intervals along the axial direction of the robotic arm, and the size of each fastening element (14) gradually decreases along the length of the robotic arm.

9. The underwater elephant trunk rope-like continuous robotic arm according to claim 1, characterized in that: The diameter of the disk in each continuous joint segment decreases sequentially from the proximal end to the distal end along the length of the robotic arm.

10. A control method for an underwater elephant trunk rope-inspired continuous robotic arm, comprising the underwater elephant trunk rope-inspired continuous robotic arm as described in any one of claims 1-9, characterized in that, The heat-concentrating method includes the following steps: S1. Establish the mapping relationship between the drive space, joint space and operation space, and solve the length change of the drive rope of each continuous joint segment according to the target end pose. S2. Control the drive device to extend and retract the corresponding drive rope (6) according to the length change, so as to realize the bending motion of the continuous joint segment; S3. During the bending motion, the torsion of the continuous joint segments is restricted by the anti-torsion skeleton, and the posture stability of the robotic arm in the underwater environment is improved by the flexible sleeve (13) and the clamping member (14).

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