An underactuated robot finger with a rigid-flexible hybrid transmission mechanism

Abstract

An underactuated robotic finger with a rigid-flexible hybrid transmission mechanism relates to the field of intelligent robotics. The driving bevel gear inside the gearbox is connected to the drive motor for transmission, while the driven bevel gear is connected to the worm. A connecting seat is fixed to the top of the gearbox, with a rotating shaft mounted in the middle to house a worm gear that meshes with the worm. The end of the knuckle housing is rotationally connected to the worm gear, the end of the swing arm is hinged to the front edge of the connecting seat, and a sliding rod is slidably mounted in a limit slot at the top. The end of the drive arm is hinged to the rear edge of the worm gear surface, and the top is hinged to the inner end of the sliding rod. The fingertip assembly includes a flexible base and a rigid frame with a spring, which is hinged to the top of the knuckle housing. The outer end of the sliding rod is hinged to a rigid support rod that is embedded in the fingertip assembly. The rigid-flexible hybrid transmission mechanism, combined with the underactuated design, is simple and easy to implement, meeting the requirements of anthropomorphic prosthetic fingers in terms of size, weight, integration, and grasping envelope. It features coupled-adaptive motion, improving flexibility and comfort.

Description

Technical Field

[0001] The present invention relates to the technical field of intelligent robots, in particular to an under-actuated robot finger with a rigid-flexible hybrid transmission mechanism. Background Art

[0002] With the continuous advancement of robotics technology, more and more research and development efforts are focused on how to better mimic the movements and functions of the human hand. As a core component in prosthetic systems, robotic fingers play an extremely important role. To improve the functionality of robotic fingers, current research focuses on humanoid design, humanoid size, low cost, and lightweight. However, existing robotic fingers generally suffer from the following significant problems:

[0003] Inadequate humanoid design: Currently, many robotic fingers still utilize traditional electrical drive systems, operated by separate mechanical devices. While these designs can achieve basic finger movements, because human finger movement is a highly coordinated and complex process, existing designs often fall short in terms of delicate grasping, pinching, and precise manipulation. Existing technologies, in particular, have significant limitations in controlling grasping, failing to effectively simulate the natural, coordinated movements of the human hand.

[0004] Limitations of humanoid size: To improve the dexterity and adaptability of prosthetic hands, the size and proportions of the fingers must closely resemble those of the human hand. However, existing prosthetic fingers often use traditional actuation methods, resulting in complex structures and significant discrepancies in size and proportions from the human hand. This makes prosthetic fingers less comfortable and natural during use. Existing prosthetic fingers often differ significantly from human fingers in length, joint spacing, and range of motion of the knuckles, affecting the wearer's operating experience and comfort.

[0005] High cost and weight: Current prosthetic finger designs typically require complex drive mechanisms and high-precision control systems, resulting in high overall device costs. This is especially true when using high-precision motors and transmission systems, which further increases manufacturing and maintenance costs. Furthermore, the large motors and mechanical components required by traditional drive methods contribute to the device's overall weight, compromising wearer comfort and the feasibility of prolonged use. Summary of the Invention

[0006] In order to address the shortcomings of the background technology, the present invention provides an under-actuated robot finger with a rigid-flexible hybrid transmission mechanism. The rigid-flexible hybrid transmission mechanism is combined with the under-actuated design to make the structure simpler and easier to use, meeting the requirements of anthropomorphic prosthetic fingers in terms of size, weight, integration and grasping envelope, and has the characteristics of coupled-adaptive motion, which greatly improves flexibility and comfort.

[0007] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: an under-actuated robot finger with a rigid-flexible hybrid transmission mechanism, comprising a driving motor, a gearbox, a connecting seat, a driving arm, a swing arm, a sliding rod, a finger joint shell and a fingertip assembly, wherein the driving motor housing is coaxially fixed to the bottom end of the gearbox, and an active bevel gear and a driven bevel gear that mesh with each other are arranged inside the gearbox, the active bevel gear is connected to the output shaft of the driving motor through a coupling for transmission, the driven bevel gear is connected to the worm through a key, and the two ends of the worm are rotatably connected to the gearbox through bearings, the connecting seat is fixedly arranged at the top of the gearbox, a rotating shaft is fixedly installed in the middle position of the connecting seat, a worm gear is rotatably sleeved on the rotating shaft and meshed with the worm, the end of the finger joint shell is rotatably connected to the worm gear through a transfer bearing, the end of the swing arm is hinged to the front edge of the connecting seat through two pins, and the top of the swing arm is extended to The limit groove is tilted backward and extends into the inside of the knuckle shell, and the slide rod is slidably installed in the limit groove, and the end of the driving arm is hinged to the rear edge of the worm gear surface through a pin shaft, and the top of the driving arm is hinged to the inner end of the slide rod through a connecting pin. The fingertip assembly includes a flexible base and a rigid frame, and the flexible base is made into the surface of the finger pad and a frame structure is set on its back. The frame structure is composed of six sections of sheet frames arranged at intervals along the length direction, among which the first two sections of sheet frames at the tip are integrally formed with the flexible base, and the remaining four sections of sheet frames adopt the rigid frame and are fixed to the flexible base. The end of the flexible base is fixed with a connecting ear and is hinged to the top of the knuckle shell through a joint axis. Springs are respectively arranged between the ends of adjacent two sections of sheet frames, and a rigid support rod is hinged at the outer end of the slide rod, and the free end of the rigid support rod is inserted through each spring in turn and supports the corresponding position of the sheet frame embedded in the tip.

[0008] Furthermore, an encoder is fixedly installed on the bottom of the driving motor.

[0009] Furthermore, a resistive pressure sensor is fixedly installed on the front side of the outer wall of the knuckle shell to measure the contact signal with the grasped object.

[0010] Furthermore, a position sensor is fixedly installed at the end of the knuckle housing to measure the relative rotational position information between the worm gear and the knuckle housing.

[0011] Furthermore, a sliding sleeve is installed inside the open end of the limiting groove.

[0012] Furthermore, a strain gauge is installed between the first two sections of the sheet-like skeleton in the skeleton structure of the fingertip assembly to measure flexible deformation information.

[0013] Furthermore, a fixed adapter is installed between the hinged end of the rigid support rod and the joint axis to maintain the stability of the relative position.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1. Based on the requirements of humanoid prosthetic fingers in terms of size, weight, integration and grasping envelope, the present invention combines a rigid-flexible hybrid transmission mechanism with an under-actuated design, making the structure more compact, reducing the complexity of traditional drive systems and control systems, thereby significantly reducing overall costs, making the robot finger structure simpler and easier to use, and having the characteristics of adaptive grasping and proportional coupled motion of the mechanism.

[0016] 2. The robot finger of the present invention has a coupled-adaptive motion function, which is specifically manifested as follows:

[0017] Anthropomorphic coupled motion in free space: When not in contact with the grasped object, the knuckle rotation and the flexible base deformation of the fingertip are linked in a fixed ratio, presenting an anthropomorphic pre-grasp action.

[0018] Adaptive movement after the knuckles contact the object: After the knuckles contact the grasped object, they stop moving, while the flexible base of the fingertips can continue to bend and deform, achieving adaptive enveloping grasp of the object.

[0019] In summary, the robot finger of the present invention exhibits significant advantages in anthropomorphic design, anthropomorphic size, low cost and light weight, and can significantly improve flexibility and comfort while ensuring efficient operation as a prosthetic finger. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the overall structure of the robot finger of the present invention;

[0021] Figure 2 It is an axonometric diagram of the fingertip assembly of the robot finger of the present invention.

[0022] In the figure: 1. Driving motor; 2. Coupling; 3. Screw; 4. Active bevel gear; 5. Gearbox; 6. Bearing 1; 7. Bearing 2; 8. Connecting seat; 9. Worm; 10. Bearing 3; 11. Driven bevel gear; 12. Worm gear; 13. Pin 1; 14. Driving arm; 15. Pin 2; 16. Rotating shaft; 17. Swing arm; 18. Connecting pin; 19. Limiting groove; 20. Sleeve; 21. Resistive pressure sensor; 22. Flexible substrate; 23. Strain gauge; 24. Position sensor; 25. Slide rod; 26. Knuckle housing; 27. Rigid support rod; 28. Spring 1; 29. ​​Spring 2; 30. Spring 3; 31. Spring 4; 32. Spring 5; 33. Encoder; 34. Rigid skeleton; 35. Joint shaft; 36. Adapter. DETAILED DESCRIPTION

[0023] The technical solutions of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0024] like Figures 1 and 2 As shown, an under-actuated robot finger with a rigid-flexible hybrid transmission mechanism includes a drive motor 1, a coupling 2, a screw 3, a driving bevel gear 4, a gearbox 5, a bearing 1 6, a bearing 2 7, a connecting seat 8, a worm 9, a bearing 3 10, a driven bevel gear 11, a worm gear 12, a pin 1 13, a drive arm 14, a pin 2 15, a rotating shaft 16, a swing arm 17, a connecting pin 18, a limit groove 19, a sliding sleeve 20, a resistive pressure sensor 21, a flexible substrate 22, a strain gauge 23, a position sensor 24, a sliding rod 25, a finger joint shell 26, a rigid support rod 27, a spring 1 28, a spring 2 29, a spring 30, a spring 4 31, a spring 5 32, an encoder 33, a rigid skeleton 34, a joint shaft 35 and an adapter 36.

[0025] Combine Figure 1As shown, the housing of the drive motor 1 is coaxially fixed to the bottom of the gearbox 5 by screws 3, and an encoder 33 is fixedly installed at the bottom of the drive motor 1. The gearbox 5 is provided with a driving bevel gear 4 and a driven bevel gear 11 that mesh with each other to transmit the motion and force output by the drive motor 1. The driving bevel gear 4 is connected to the output shaft of the drive motor 1 through a coupling 2 for transmission. The coupling 2 is rotationally connected to the gearbox 5 through bearing 2 7. The two ends of the worm 9 are rotationally connected to the gearbox 5 through bearing 1 6 and bearing 3 10 respectively. The driven bevel gear 11 is connected to the worm 9 by a key. The connecting seat 8 is fixedly set at the top of the gearbox 5, and a rotating shaft 16 is fixedly installed in the middle position of the connecting seat 8. The worm gear 12 is rotatably sleeved on the rotating shaft 16 and meshes with the worm 9 to transmit the motion and force output by the driven bevel gear 11. The knuckle housing 26 is hollow and has a connecting piece at its end. It is rotatably connected to the worm gear 12 via an adapter bearing. A resistive pressure sensor 21 is fixedly mounted on the front outer wall of the knuckle housing 26 to measure contact signals with the grasped object. A position sensor 24 is fixedly mounted on the connecting piece at the end of the knuckle housing 26 to measure the relative rotational position of the worm gear 12 and the knuckle housing 26. The end of the swing arm 17 is hingedly connected to a pin 2 15 fixedly mounted on the front edge of the connecting base 8 to form a revolving pair. A limit slot 19 extends from the top of the swing arm 17 and extends rearwardly into the interior of the knuckle housing 26. A sliding sleeve 20 is mounted inside the open end of the limit slot 19. The slide rod 25 slides within the limit slot 19 to form a sliding pair. The end of the drive arm 14 is hingedly connected to a pin 13 fixedly mounted on the rear edge of the worm gear 12 to form a revolving pair. The top of the drive arm 14 is hingedly connected to the inner end of the slide rod 25 via a connecting pin 18.

[0026] Combine Figures 1 and 2As shown, a fingertip assembly is mounted on the top of the knuckle housing 26. The assembly is composed of a flexible substrate 22 and a rigid framework 34. The flexible substrate 22 is made of a flexible material, with a framework structure positioned on its back. This framework consists of six segments of sheet-like framework spaced apart along the length. The first two segments of the sheet-like framework at the tip are integrally formed from the same material as the flexible substrate 22. Strain gauges 23 are installed between the first two segments to measure flexible deformation. The remaining four segments are fixed to the flexible substrate 22 using the rigid framework 34. A connecting lug is fixed to the end of the flexible substrate 22 and hingedly connected to the top of the knuckle housing 26 via a joint axis 35, forming a revolute joint. This allows the fingertip assembly to rotate relative to the knuckle housing 26 about this joint axis 35. Except for the tip, all segments of the framework have through-holes at their centers. Springs 1 28, 29, 30, 4 31, and 5 32 are positioned sequentially between the ends of two adjacent segments, from the tip to the front. A rigid support rod 27 is hingedly provided at the outer end of the slide rod 25, and the free end of the rigid support rod 27 is sequentially inserted through the through holes of each sheet-like frame in the skeleton structure as well as spring 1 28, spring 29, spring 30, spring 4 31, and spring 5 32, and supports the corresponding position of the sheet-like frame embedded in the tip to transmit the movement and force from the slide rod 25. In addition, a fixed adapter 36 is installed between the hinged end of the rigid support rod 27 and the joint axis 35 to keep the relative position between the hinged end of the rigid support rod 27 and the joint axis 35 stable.

[0027] The innovation of the robot finger of the present invention is:

[0028] Rigid-Flexible Hybrid Transmission Mechanism: This hybrid transmission mechanism utilizes a combination of rigid and flexible materials. While the rigid structure supports the flexible structure, it transmits and regulates motion, enabling coordinated multi-degree-of-freedom movement of the fingers. This design significantly enhances finger flexibility and adaptability while ensuring structural stability and reliability. Compared to traditional hardware-based drives, the rigid-flexible hybrid transmission mechanism enables natural grasping motion without adding excessive weight or complexity.

[0029] Under-actuated design: By reducing the number of drive components and leveraging the synergy of transmission mechanisms to achieve joint motion control, the under-actuated design helps further reduce cost and weight. Compared with traditional drive designs, it can achieve coordinated motion of more joints with fewer drive resources, making finger movements smoother and more precise.

[0030] Humanoid size and natural finger movement, low cost and light weight: Through size design and structural planning, the prosthetic finger can better fit the size proportions of the human hand, making the finger length, joint angle, inter-knuckle spacing, etc. closer to the natural structure of human fingers. Through the optimized design of the rigid-flexible hybrid transmission mechanism, the complexity of the motor, transmission components and control system in the traditional drive system is reduced, thereby significantly reducing the overall cost. The structure is simpler and easier, and the design is compact, which helps to effectively reduce the overall weight of the finger. The wearer can maintain a high level of comfort during long-term use and avoid fatigue caused by excessive weight.

[0031] 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 configurations without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations coming within the meaning and range of equivalents of the claims are intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0032] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. An underactuated robot finger with a rigid-flexible hybrid transmission mechanism, characterized by: The invention comprises a driving motor (1), a gear box (5), a connecting seat (8), a driving arm (14), a swing arm (17), a slide bar (25), a finger joint housing (26) and a fingertip assembly. The housing of the driving motor (1) is coaxially fixed to the bottom end of the gear box (5). An active bevel gear (4) and a driven bevel gear (11) that mesh with each other are provided inside the gear box (5). The active bevel gear (4) is connected to the output shaft of the driving motor (1) through a coupling (2). The driven bevel gear (11) is connected to a worm (9) through a key. The two ends of the rod (9) are rotatably connected to the gear box (5) through bearings, the connecting seat (8) is fixedly arranged on the top of the gear box (5), the middle position of the connecting seat (8) is fixedly installed with a rotating shaft (16), the rotating shaft (16) is rotatably sleeved with a worm wheel (12) and meshed with the worm (9), the end of the knuckle shell (26) is rotatably connected to the worm wheel (12) through a transfer bearing, the end of the swing arm (17) is hinged to the front edge of the connecting seat (8) through a second pin (15), and a limit slot (19) is extended from the top of the swing arm (17) and extends backward. The fingertip assembly is tilted and extends into the interior of the finger joint shell (26), and the slide rod (25) is slidably installed in the limit groove (19). The end of the driving arm (14) is hinged to the rear edge of the worm gear (12) through a pin shaft (13), and the top of the driving arm (14) is hinged to the inner end of the slide rod (25) through a connecting pin (18). The fingertip assembly includes a flexible base (22) and a rigid skeleton (34). The flexible base (22) is made into the surface of the fingertip and a skeleton structure is set on its back side. The skeleton structure is composed of six sections of sheet skeletons arranged at intervals along the length direction. The first two sections of the sheet skeleton at the tip are integrally formed with the flexible base (22), and the remaining four sections of the sheet skeleton adopt the rigid skeleton (34) and are fixed to the flexible base (22). The end of the flexible base (22) is fixed with a connecting ear and is hinged to the top of the finger joint shell (26) through a joint shaft (35). Springs are respectively arranged between the ends of the two adjacent sections of the sheet skeleton, and a rigid support rod (27) is hingedly arranged at the outer end of the slide rod (25). The free end of the rigid support rod (27) is sequentially inserted through each spring and supports the corresponding position of the sheet skeleton embedded in the tip.

2. The underactuated robot finger with a rigid-flexible hybrid transmission mechanism according to claim 1, characterized in that: An encoder (33) is fixedly mounted on the bottom of the driving motor (1).

3. The underactuated robot finger with a rigid-flexible hybrid transmission mechanism according to claim 1, characterized in that: A resistive pressure sensor (21) is fixedly mounted on the front side of the outer wall of the knuckle housing (26) to measure a contact signal with the grasped object.

4. The underactuated robot finger with a rigid-flexible hybrid transmission mechanism according to claim 1, characterized in that: A position sensor (24) is fixedly installed at the end of the knuckle housing (26) to measure relative rotational position information between the worm gear (12) and the knuckle housing (26).

5. The underactuated robot finger with a rigid-flexible hybrid transmission mechanism according to claim 1, characterized in that: A sliding sleeve (20) is installed inside the opening end of the limiting groove (19).

6. The underactuated robot finger with a rigid-flexible hybrid transmission mechanism according to claim 1, characterized in that: A strain gauge (23) is installed between the first two sections of the sheet-like skeleton in the skeleton structure of the fingertip assembly to measure flexible deformation information.

7. The underactuated robot finger with a rigid-flexible hybrid transmission mechanism according to claim 1, characterized in that: A fixed adapter (36) is installed between the hinged end of the rigid support rod (27) and the joint shaft (35) to maintain the stability of the relative position.

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