Variable cross-section tendon-driven 3D-printed five-fingered dexterous hand

Abstract

The application relates to a 3D-printed five-fingered dexterous hand based on a variable cross-section tendon driving, which comprises a palm assembly, the inside of which is provided with a tendon guide groove; a general finger, the inside of which is provided with a variable cross-section driving tendon for transmitting bidirectional driving force, the proximal end of the variable cross-section driving tendon being arranged in the tendon guide groove of the palm assembly; a thumb, the proximal end of which is connected with the palm assembly; a forearm assembly, the proximal end of the palm assembly being connected with the forearm assembly; and a distributed linear driving system, the distributed linear driving system comprising a plurality of linear driving units. The variable cross-section tendon of the general finger is combined with the linear driving unit, and the antagonistic ropes of a traditional hand are eliminated; the palm adopts a three-layer superimposed architecture, the tendon guide groove is directly integrated on the middle layer, and modular assembly is facilitated; the variable cross-section tendon mounting interface design makes the maintenance of a complex electromechanical system more convenient, and the easy-maintenance requirement of the dexterous hand in actual application is met.

Description

Technical Field

[0001] This invention relates to the field of robotic hand technology, and in particular to a 3D-printed five-finger dexterous hand based on variable cross-section tendon drive. Background Technology

[0002] Multi-fingered dexterous hands are the core components for robots to achieve complex grasping and fine manipulation. Traditional dexterous hands typically contain a large number of mechanical parts, which are not only extremely cumbersome to assemble and expensive to manufacture, but also difficult to maintain.

[0003] In terms of drive system layout, existing dexterous hands mainly face two extremes: one is to place all motors in the forearm, driven by long Teflon conduits and cables. While this reduces the weight of the hand, it results in extremely complex tendon routing, high friction, and a high susceptibility to coupling interference. The other is to concentrate most of the motors inside the hand. This simplifies the wiring but makes the hand too large and greatly increases the rotational inertia of the robotic arm's end effector, severely affecting the robotic arm's dynamic response capability. In addition, traditional tethered dexterous hands, because the tether can only be pulled and not pushed, must use complex antagonistic tether arrangements or additional return springs, further encroaching on the limited internal space. Summary of the Invention

[0004] This invention provides a 3D-printed five-finger dexterous hand based on variable cross-section tendon drive, aiming to solve at least one of the technical problems existing in the prior art.

[0005] The technical solution of this invention is a 3D-printed five-fingered dexterous hand based on variable cross-section tendon drive, comprising: Hand assembly; A universal finger, the proximal end of which is connected to the palm assembly; The thumb, the proximal end of which is connected to the palm assembly; Forearm assembly, the proximal end of the palm assembly is connected to the forearm assembly; A distributed linear drive system includes multiple linear drive units, which are respectively disposed inside the palm assembly and the forearm assembly.

[0006] Furthermore, the palm assembly includes a palm pad layer, a middle layer, and a back cover layer; The surface of the palm pad is a high-friction contact surface; A tendon guide groove is provided on the side of the middle layer near the palm pad layer; The middle layer is also provided with a groove on the side near the back of the hand cover layer, the groove being used to accommodate multiple linear drive units integrated inside the palm assembly; The back of the hand cover is a rigid protective plate used to seal the internal structure of the palm assembly.

[0007] Furthermore, the universal finger includes a finger base, a metacarpophalangeal rotatory joint, a first proximal phalanx, a metacarpophalangeal flexion-extension joint, a second proximal phalanx, a proximal interphalangeal joint, a middle phalanx, a distal interphalangeal joint, and a distal phalanx, connected in sequence. It also includes proximal interphalangeal joint driving tendons, first metacarpophalangeal joint driving tendons, second metacarpophalangeal joint driving tendons, and variable cross-section passive coupling tendons. The first end of the proximal interphalangeal joint driving tendon is connected to the middle phalanx, the middle part of the proximal interphalangeal joint driving tendon passes through the second tendon channel built into the second proximal phalanx and the first tendon channel built into the first proximal phalanx in sequence, and the second end of the proximal interphalangeal joint driving tendon extends proximally and is connected to an external driving source. The first metacarpophalangeal joint driving tendon and the second metacarpophalangeal joint driving tendon are arranged in parallel. The first ends of the first metacarpophalangeal joint driving tendon and the second metacarpophalangeal joint driving tendon are respectively connected to the second proximal phalanx. The second ends of the first metacarpophalangeal joint driving tendon and the second metacarpophalangeal joint driving tendon extend proximally and are respectively connected to an external driving source. The first end of the variable cross-section passive coupling tendon is connected to the distal phalanx. The middle part of the cross-section passive coupling tendon passes through the third tendon channel built into the middle phalanx and extends along the surface of the middle phalanx and the surface of the second proximal phalanx. The second end of the cross-section passive coupling tendon is connected to the second proximal phalanx. The variable cross-section passive coupling tendon is used to mechanically couple the proximal and distal interphalangeal joints, thereby achieving linkage between the proximal and distal interphalangeal joints.

[0008] Furthermore, the proximal interphalangeal joint driving tendon, the first metacarpophalangeal joint driving tendon, and the second metacarpophalangeal joint driving tendon are all variable cross-section driving tendons, and the metacarpophalangeal roll joint, the metacarpophalangeal pitch joint, the proximal interphalangeal joint, and the distal interphalangeal joint are all flexible hinge joints. The proximal interphalangeal joint driving tendon, the first metacarpophalangeal joint driving tendon, and the second metacarpophalangeal joint driving tendon have varying cross-sectional dimensions along their respective length directions. In the bending regions corresponding to the metacarpophalangeal joints, metacarpophalangeal joints, proximal interphalangeal joints, and distal interphalangeal joints, the thickness of the proximal interphalangeal joint driving tendon, the first metacarpophalangeal joint driving tendon, and the second metacarpophalangeal joint driving tendon is reduced to provide maximum flexibility. In the weak bending region outside the planes of the corresponding metacarpophalangeal joints, metacarpophalangeal joints, proximal interphalangeal joints, and distal interphalangeal joints, the thickness of the proximal interphalangeal joint driving tendon, the first metacarpophalangeal joint driving tendon, and the second metacarpophalangeal joint driving tendon is increased to improve flexion resistance.

[0009] Furthermore, the thumb includes a carpal joint, an interphalangeal joint, and a metacarpophalangeal joint connected in sequence, and also includes a carpal joint drive rope for driving the carpal joint, a metacarpophalangeal joint rope for driving the metacarpophalangeal joint, and a thumb variable cross-section passive coupling tendon for connecting the interphalangeal joint and the metacarpophalangeal joint.

[0010] Furthermore, the forearm assembly includes an open interface for quick finger replacement, a drive array, a PCB circuit board, and a wrist interface; The proximal ends of the first and second metacarpophalangeal joint driving tendons of the universal finger and the connection ends of the linear drive unit installed in the forearm assembly are exposed at the open interface to achieve modular separation and quick maintenance. The remaining eleven linear drive units place most of their mass at the rear to reduce end-effector rotational inertia. The drive array is composed of the remaining eleven linear drive units arranged densely, and remotely drives the dexterous hand across the wrist joint by driving tendons at the first and second metacarpophalangeal joints of each general finger.

[0011] Furthermore, the distributed linear drive system includes fifteen linear drive units, of which four linear drive units are integrated inside the palm assembly, and the remaining eleven linear drive units are disposed inside the forearm assembly.

[0012] Furthermore, four linear drive units integrated inside the palm assembly drive the proximal interphalangeal joint drive tendons of the four universal fingers. The proximal ends of the proximal interphalangeal joint drive tendons are connected to the linear output ends of the corresponding linear drive units. The linear drive units achieve the bending and stable return movements of the corresponding universal fingers by applying tension or thrust to the proximal interphalangeal joint drive tendons.

[0013] Furthermore, the eleven linear drive units integrated inside the forearm assembly are used to drive the other joint degrees of freedom of each universal finger. In order to balance the complexity of the wiring and the rotational inertia of the dexterous hand end, the forearm assembly and the palm assembly are set separately. The eleven linear drive units in the forearm assembly cross the wrist assembly to remotely drive the universal finger and the thumb. The eleven linear drive units integrated inside the forearm assembly are divided into a first-layer drive unit, a second-layer drive unit, and a third-layer drive unit from front to back. The first-layer drive unit includes four linear drive units arranged side by side, the second-layer drive unit includes four linear drive units arranged side by side, and the third-layer drive unit includes three linear drive units arranged side by side. The four drive units of the first layer drive unit are respectively connected to the first metacarpophalangeal joint drive tendons of the four universal fingers. The four drive units of the second layer drive unit are respectively connected to the second metacarpophalangeal joint drive tendons of the four universal fingers. The three drive units of the third layer drive unit are respectively connected to the first carpometacarpophalangeal joint drive rope on the thumb side, the second carpometacarpophalangeal joint drive rope on the other side of the thumb, and the metacarpophalangeal joint drive rope of the thumb.

[0014] Furthermore, the linear drive unit includes a brushless hollow cup motor, a gear reduction mechanism, a trapezoidal lead screw, and an output nut that cooperates with the trapezoidal lead screw; The rotational motion of the brushless hollow cup motor is transmitted to the trapezoidal lead screw through the gear reduction mechanism, and is converted into the linear motion of the output nut. The output nut is fixedly connected to the proximal end of the variable cross-section driving tendon.

[0015] The beneficial effects of this invention are: The aforementioned 3D-printed five-fingered dexterous hand based on variable cross-section tendon actuation employs a distributed linear drive layout. Some actuators are placed within the palm assembly to simplify wiring, while most actuators are positioned in the forearm assembly to reduce end-effector inertia. The variable cross-section tendons of the universal fingers, combined with linear drive units, eliminate the antagonistic cords of traditional hands. The palm uses a three-layer stacked architecture, with tendon guide grooves directly integrated into the middle layer for easy modular assembly. The variable cross-section tendon mounting interface design makes maintenance of complex electromechanical systems more convenient, meeting the maintainability requirements of dexterous hands in practical applications.

[0016] The aforementioned 3D-printed five-finger dexterous hand based on variable cross-section tendon drive can achieve assembly-free finger manufacturing through integrated 3D printing technology while ensuring dexterity. It also adopts a distributed linear drive system and a three-layer palm component architecture to achieve efficient transmission, compact layout and lightweight design of the whole hand system. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of a 3D-printed five-fingered dexterous hand based on variable cross-section tendon drive in an embodiment of the present invention.

[0018] Figure 2 This is a schematic diagram of the other side of the 3D-printed five-fingered dexterous hand based on variable cross-section tendon drive in an embodiment of the present invention.

[0019] Figure 3 This is a schematic diagram of the structure of a universal finger in a 3D-printed five-finger dexterous hand based on variable cross-section tendon drive in an embodiment of the present invention.

[0020] Figure 4 This is a schematic diagram of the structure on the other side of the universal finger in the 3D-printed five-finger dexterous hand based on variable cross-section tendon drive in an embodiment of the present invention.

[0021] Figure 5 This is a schematic diagram of the structure of a universal finger in a five-finger dexterous hand based on variable cross-section tendon-driven 3D printing in an embodiment of the present invention.

[0022] Figure 6 This is a schematic cross-sectional view of the printing of a universal finger in a five-finger dexterous hand based on variable cross-section tendon-driven 3D printing in an embodiment of the present invention.

[0023] Figure 7 This is a schematic diagram of the structure of the thumb in a 3D-printed five-finger dexterous hand based on variable cross-section tendon drive in an embodiment of the present invention.

[0024] Figure 8 This is an exploded structural diagram of the palm component in a 3D-printed five-finger dexterous hand based on variable cross-section tendon drive in an embodiment of the present invention.

[0025] Figure 9 This is an exploded structural diagram of the forearm component in a 3D-printed five-finger dexterous hand based on variable cross-section tendon drive in an embodiment of the present invention.

[0026] Figure 10 This is a schematic diagram of the linear drive unit in a 3D-printed five-finger dexterous hand based on variable cross-section tendon drive in an embodiment of the present invention.

[0027] Reference numerals in the attached figures: 1. General finger; 11. Finger base; 12. Metacarpophalangeal rotator joint; 13. First proximal phalanx; 14. Metacarpophalangeal flexion-extension joint; 15. Second proximal phalanx; 16. Proximal interphalangeal joint; 17. Middle phalanx; 18. Distal interphalangeal joint; 19. Distal phalanx; 110. Tendon driving the proximal interphalangeal joint; 111. Tendon driving the first metacarpophalangeal joint; 112. Tendon driving the second metacarpophalangeal joint; 113. Variable cross-section passively coupled tendon; 11 4. Tensioning pin; 115. Oil reservoir micro-groove; 116. Pre-bending angle; 2. Thumb; 21. Wrist-metacarpophalangeal joint; 221. First wrist-metacarpophalangeal joint drive rope; 222. Second wrist-metacarpophalangeal joint drive rope; 23. Interphalangeal joint; 24. Metacarpophalangeal joint; 25. Metacarpophalangeal joint rope; 26. Thumb variable cross-section passively coupled tendon; 27. Protective sleeve; 3. Palm assembly; 31. Palm pad layer; 32. Intermediate layer; 33. Back of hand cover layer; 34. Tendon guide groove; 4. Forearm assembly; 41. Open interface; 42. Drive array; 43. PCB circuit board; 44. Wrist interface; 5. Linear drive unit; 51. Brushless hollow cup motor; 52. Gear reduction mechanism; 53. Trapezoidal lead screw; 54. Output nut. Detailed Implementation

[0028] The following will provide a clear and complete description of the concept, specific structure, and technical effects of the present invention in conjunction with the embodiments and accompanying drawings, so as to fully understand the purpose, solution, and effects of the present invention. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0029] It should be noted that, unless otherwise specified, when a feature is referred to as "fixed" or "connected" to another feature, it can be directly fixed or connected to the other feature, or indirectly fixed or connected to the other feature. Furthermore, the descriptions of "upper," "lower," "left," "right," "top," and "bottom" used in this invention are only relative to the relative positional relationships of the various components of the invention in the accompanying drawings.

[0030] Furthermore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is for the purpose of describing particular embodiments only and not for limiting the invention. The term "and / or" as used herein includes any combination of one or more of the associated listed items.

[0031] It should be understood that although the terms first, second, third, etc., may be used in this disclosure to describe various elements, these elements should not be limited to these terms. These terms are only used to distinguish elements of the same type from one another. For example, without departing from the scope of this disclosure, a first element may also be referred to as a second element, and similarly, a second element may also be referred to as a first element.

[0032] Reference Figures 1 to 10 In some embodiments, the technical solution of the present invention is a 3D-printed five-fingered dexterous hand based on variable cross-section tendon drive, referring to... Figure 1 and Figure 2 The aforementioned 3D-printed five-fingered dexterous hand based on variable cross-section tendon drive includes: Hand component 3; A universal finger 1, the proximal end of which is connected to the palm assembly 3; Thumb 2, the proximal end of which is connected to the palm assembly 3; Forearm assembly 4, the proximal end of the palm assembly 3 is connected to the forearm assembly 4; A distributed linear drive system includes multiple linear drive units 5, which are respectively disposed inside the palm assembly 3 and the forearm assembly 4.

[0033] The beneficial effects of this invention are: The aforementioned 3D-printed five-fingered dexterous hand based on variable cross-section tendon drive adopts a distributed linear drive layout, placing some actuators within the palm assembly 3 to simplify wiring, and placing most of the actuators at the rear of the forearm assembly 4 to reduce end-effector inertia; the variable cross-section tendon of the universal finger 1, combined with the linear drive unit 5, eliminates the antagonistic cords of traditional hands; the palm adopts a three-layer stacked architecture, with the tendon guide groove 34 directly integrated on the middle layer 32, facilitating modular assembly; the variable cross-section tendon mounting interface design makes the maintenance of complex electromechanical systems more convenient, meeting the maintainability requirements of dexterous hands in practical applications.

[0034] The aforementioned 3D-printed five-finger dexterous hand based on variable cross-section tendon drive can achieve assembly-free finger manufacturing through integrated 3D printing technology while ensuring dexterous operation capabilities. It also adopts a distributed linear drive system and a three-layer palm component architecture to achieve efficient transmission, compact layout and lightweight design of the entire hand system.

[0035] The aforementioned 3D-printed five-finger dexterous hand based on variable cross-section tendon drive includes four universal fingers 1, a thumb 2, a palm assembly 3, a forearm assembly 4, and a distributed linear drive system. Each finger (including the variable cross-section tendon) is integrally formed using flexible material through 3D printing. Utilizing the flexion resistance of the thickened tendon area, a single tendon can achieve both flexion and retraction movements of the finger, eliminating the need for antagonistic cables. The palm assembly 3 employs a three-layer composite structure consisting of a palm pad 31, a middle layer 32, and a back cover layer 33. The middle layer 32 has guide grooves to constrain and regulate the routing of the push-pull tendons. The 3D-printed five-finger dexterous hand based on variable cross-section tendon drive uses fifteen linear drive units 5, four of which are integrated into the palm to drive the interphalangeal joints 23, and eleven are integrated into the forearm assembly 4 to reduce end-effector inertia, forming a distributed drive architecture. The drive module and tendon connection interface are located on the side for easy maintenance. The thumb 2 uses a hybrid transmission structure combining wrist-palm joint 21 cable drive and internal variable cross-section tendon linkage. The aforementioned 3D-printed five-fingered dexterous hand based on variable cross-section tendon drive adopts a distributed linear drive architecture, with the distributed linear drive system embedded inside the palm component 3 and the forearm component 4 respectively. This invention achieves finger-free assembly, lightweight design, and high maintainability of the dexterous hand system, meeting the requirements of dynamic and agile grasping operations.

[0036] The universal finger 1 is made of a single flexible material and is integrally formed by 3D printing without any mechanical assembly or connection.

[0037] Multiple universal fingers 1 and thumb 2 are mounted on the front end of the palm assembly 3, and the forearm assembly 4 is connected to the palm assembly 3 via the wrist interface 44.

[0038] The 3D-printed five-fingered dexterous hand based on variable cross-section tendon drive adopts a distributed linear drive architecture, with linear drive units 5 embedded inside the palm component 3 and the forearm component 4 respectively.

[0039] Furthermore, refer to Figure 8 The palm assembly 3 includes a palm pad layer 31, a middle layer 32, and a back of hand cover layer 33; The surface of the palm pad layer 31 is a high-friction contact surface; The middle layer 32 is provided with a tendon guide groove 34 on the side near the palm pad layer 31; The intermediate layer 32 is also provided with a groove on the side near the back of the hand cover layer 33. The groove is used to accommodate multiple linear drive units 5 integrated inside the palm assembly 3. The back of the hand cover 33 is a rigid protective plate used to seal the internal structure of the palm assembly 3.

[0040] Specifically, the palm assembly 3 consists of a palm pad layer 31, a middle layer 32, and a back cover layer 33, arranged sequentially from the palm to the back of the hand. The palm assembly 3 adopts a three-layer composite structure. The palm pad layer 31 is printed with flexible material to provide a high-friction contact surface. The tendon guide groove 34 is used to regulate the routing of the first metacarpophalangeal joint driving tendon 111 and the second metacarpophalangeal joint driving tendon 112.

[0041] The palm assembly 3 adopts a modular three-layer stacked structure, consisting of a palm pad layer 31, an intermediate layer 32, and a back cover layer 33, arranged sequentially from the palm to the back of the hand. The palm pad layer 31 is printed using a flexible material to provide a high-friction contact surface; the front of the intermediate layer 32 is machined with regularly arranged tendon guide grooves 34, through which the first metacarpophalangeal joint driving tendon 111 and the second metacarpophalangeal joint driving tendon 112 from each common finger 1 pass through the tendon guide grooves 34 and are radially constrained to prevent lateral flexion when pushed; the interior of the intermediate layer 32 also has four linear drive units 5 for driving the proximal interphalangeal joint driving tendon 110 of the fingers, shortening the transmission path; the back cover layer 33 is a rigid protective plate used to enclose the entire palm structure.

[0042] Furthermore, refer to Figures 3 to 6 The universal finger 1 includes a finger base 11, a metacarpophalangeal rolling joint 12, a first proximal phalanx 13, a metacarpophalangeal pitching joint 14, a second proximal phalanx 15, a proximal interphalangeal joint 16, a middle phalanx 17, a distal interphalangeal joint 18, and a distal phalanx 19 connected in sequence. It also includes a proximal interphalangeal joint driving tendon 110, a first metacarpophalangeal joint driving tendon 111, a second metacarpophalangeal joint driving tendon 112, and a variable cross-section passive coupling tendon 113. The first end of the proximal interphalangeal joint driving tendon 110 is connected to the middle phalanx 17. The middle part of the proximal interphalangeal joint driving tendon 110 passes through the second tendon channel built into the second proximal phalanx 15 and the first tendon channel built into the first proximal phalanx 13 in sequence. The second end of the proximal interphalangeal joint driving tendon 110 extends proximally and is connected to an external driving source. The first metacarpophalangeal joint driving tendon 111 and the second metacarpophalangeal joint driving tendon 112 are arranged in parallel. The first ends of the first metacarpophalangeal joint driving tendon 111 and the second metacarpophalangeal joint driving tendon 112 are respectively connected to the second proximal phalanx 15. The second ends of the first metacarpophalangeal joint driving tendon 111 and the second metacarpophalangeal joint driving tendon 112 extend proximally and are respectively connected to an external driving source. The first end of the variable cross-section passive coupling tendon 113 is connected to the distal phalanx 19. The middle part of the cross-section passive coupling tendon passes through the third tendon channel built into the middle phalanx 17 and extends along the surface of the middle phalanx 17 and the surface of the second proximal phalanx 15. The second end of the cross-section passive coupling tendon is connected to the second proximal phalanx 15. The variable cross-section passive coupling tendon 113 is used to mechanically couple the proximal interphalangeal joint 16 and the distal interphalangeal joint 18, thereby realizing the linkage between the proximal interphalangeal joint 16 and the distal interphalangeal joint 18.

[0043] Specifically, four universal fingers 1 are provided, arranged side by side; the proximal end of each universal finger 1 is connected to the palm assembly 3. A variable cross-section driving tendon, consisting of a proximal interphalangeal joint driving tendon 110, a first metacarpophalangeal joint driving tendon 111, and a second metacarpophalangeal joint driving tendon 112, runs through the interior of each universal finger 1. This variable cross-section driving tendon is extremely thin in the bending region to provide flexibility, and thickens in the weak bending region to improve flexion resistance, thereby enabling it to transmit linear thrust when pushed proximally, achieving finger return and extension.

[0044] The universal finger 1 can achieve bidirectional push-pull actuation using only a single driving tendon without complex assembly. Simultaneously, a special structural design overcomes the friction and relaxation issues of 3D-printed flexible materials, meeting the requirements of high efficiency, lightweight design, and high reliability for robotic grasping. The universal finger 1 adopts an integrated design of phalanx, flexible hinge, and tendon, using a single flexible material for one-time 3D printing, completely eliminating the traditional assembly process and significantly shortening the manufacturing cycle. It innovatively employs a variable cross-section tendon design, which can transmit thrust like a rigid linkage during the return phase, completely eliminating the need for antagonistic ropes or return springs and greatly reducing the complexity of the drive system. An oil storage microgroove 115 and a lateral tensioning pin 114 are designed inside the phalanx, effectively reducing frictional resistance and compensating for initial relaxation during 3D printing. The pre-bending angle 116 of the flexible hinge uses structural prestress to resist material creep, ensuring precise rebound after finger grasping. Furthermore, by introducing IMU sensors combined with data-driven kinematic modeling methods, the problem of establishing analytical equations for the nonlinear deformation of flexible 3D printing materials was successfully overcome, enabling high-fidelity state estimation and precise closed-loop control of the dexterous hand.

[0045] Reference Figure 3 and Figure 4The integrated 3D-printed dexterous finger's internal tendon and joint structure includes a variable cross-section driving tendon passing through the first proximal phalanx 13 and the second proximal phalanx 15, a variable cross-section passive coupling tendon 113 passing through the middle phalanx 17, an oil reservoir microgroove 115, and a laterally inserted tension pin 114. The distal ends of the three variable cross-section driving tendons are fixed to the corresponding phalanges, and their proximal ends extend from a base and connect to an external driving source. The two ends of the variable cross-section passive coupling tendon 113 are respectively connected to and fixed to the second proximal phalanx 15 and the distal phalanx 19. In addition, a sensor mounting slot is formed on the surface or inside the distal phalanx 19, and an IMU (Inertial Measurement Unit) is fixed in the mounting slot for real-time capture of the spatial posture of the fingertip. Except for the IMU, all the above components are made of a single flexible material and formed in a single 3D printing step, forming a continuous integrated structure.

[0046] Furthermore, refer to Figures 3 to 6 The proximal interphalangeal joint driving tendon 110, the first metacarpophalangeal joint driving tendon 111 and the second metacarpophalangeal joint driving tendon 112 are all variable cross-section driving tendons, and the metacarpophalangeal roll joint 12, the metacarpophalangeal pitch joint 14, the proximal interphalangeal joint 16 and the distal interphalangeal joint 18 are all flexible hinge joints. The proximal interphalangeal joint driving tendon 110, the first metacarpophalangeal joint driving tendon 111, and the second metacarpophalangeal joint driving tendon 112 have varying cross-sectional dimensions along their respective length directions. In the bending regions corresponding to the metacarpophalangeal roll joint 12, metacarpophalangeal pitch joint 14, proximal interphalangeal joint 16 and distal interphalangeal joint 18, the thickness of the proximal interphalangeal joint driving tendon 110, the first metacarpophalangeal joint driving tendon 111 and the second metacarpophalangeal joint driving tendon 112 is reduced to provide maximum flexibility. In the weak bending region outside the plane of the corresponding metacarpophalangeal roll joint 12, metacarpophalangeal pitch joint 14, proximal interphalangeal joint 16 and distal interphalangeal joint 18, the thickness of the proximal interphalangeal joint driving tendon 110, the first metacarpophalangeal joint driving tendon 111 and the second metacarpophalangeal joint driving tendon 112 is increased to improve flexion resistance.

[0047] Specifically, the variable cross-section driving tendon has a varying cross-sectional size along its length, with a reduced thickness in the bending region corresponding to the flexible hinge joint and an increased thickness in the interior or non-bending region of the corresponding phalanx to improve its resistance to flexion. This allows the variable cross-section driving tendon to transmit effective thrust within the tendon guide groove 34 of the intermediate layer 32 when the linear drive unit 5 pushes the output nut 54 forward.

[0048] Furthermore, the proximal interphalangeal joint driving tendon 110, the first metacarpophalangeal joint driving tendon 111, and the second metacarpophalangeal joint driving tendon 112 of the universal finger 1 achieve stable return movement of the finger by relying on the anti-flexion ability provided by the increased thickness area when the finger is in the return phase, without the need to configure antagonistic ropes or return springs. The metacarpophalangeal rolling joint 12 is composed of two orthogonally arranged single-degree-of-freedom flexible hinge joints connected in series, which respectively realize the mechanical decoupling of finger pitch and roll movements; The middle phalanx 17 is also provided with a laterally inserted tensioning pin 114, which abuts against the variable cross-section passive coupling tendon 113. The tensioning pin 114 is used to tension the variable cross-section passive coupling tendon 113 to compensate for the initial relaxation during the 3D printing manufacturing process. Oil storage microgrooves 115 are arrayed on the inner walls of the first tendon channel, the second tendon channel, and the third tendon channel. The oil storage microgroove 115 is used to reduce the contact area between the corresponding variable cross-section driving tendon and the inner wall of the first tendon channel, the second tendon channel, or the third tendon channel, and to contain grease to reduce frictional resistance during operation. The metacarpophalangeal roll joint 12, the metacarpophalangeal pitch joint 14, the proximal interphalangeal joint 16, and the distal interphalangeal joint 18 have a preset pre-bending angle 116 in the initial integrated 3D printing state. The pre-bending angle 116 is used to provide the return torque of the joint and resist the creep and stress relaxation of the flexible material, so as to ensure that the flexible hinge can spring back to the initial position after repeated driving. The distal phalanx 19 is provided with a sensor mounting slot, and an IMU inertial measurement unit for real-time acquisition of spatial posture and motion data of the fingertip is fixed in the sensor mounting slot.

[0049] Reference Figure 6 The pre-bending angle 116 is formed by the angle between the first ray and the second ray, wherein the first ray runs from the center of the distal interphalangeal joint 18 to the center of the proximal interphalangeal joint 16, and the second ray runs from the center of the proximal interphalangeal joint 16 to the center of the metacarpophalangeal joint 14.

[0050] Specifically, the transmission and return decoupling principle of the universal finger 1 is as follows: the variable cross-section driving tendon has a varying cross-sectional size along its length. In the bending region corresponding to the flexible hinge joint, the thickness of the variable cross-section driving tendon decreases to provide maximum bending compliance; in the weak bending region outside the joint plane, the thickness of the variable cross-section driving tendon increases to improve flexion resistance. When an external driving source pulls the driving tendon, the tension overcomes the resistance of the flexible hinge, causing the finger to bend. When the finger is in the return phase, the driving source reverses the drive, and the variable cross-section driving tendon, relying on the flexion resistance provided by the increased thickness region, can stably transmit the thrust. Combined with the inherent elasticity of the flexible hinge, it achieves stable extension and return movement of the finger, thus replacing the antagonistic rope or return spring mechanism in traditional mechanical fingers. At the same time, the variable cross-section passive coupling tendon 113, because it connects the proximal interphalangeal joint 16 and the distal interphalangeal joint 18, can realize the mechanical linkage between the two joints.

[0051] The friction optimization and compensation principle of the universal finger 1 is as follows: Oil-retaining microgrooves 115 are arrayed on the inner wall of the tendon channel within the phalanx. The design of these microgrooves not only reduces the physical contact area between the variable cross-section driving tendon and the inner wall of the channel but also accommodates injected grease, thereby significantly reducing frictional resistance during long-term operation. Simultaneously, since the 3D printing process easily causes initial relaxation of the flexible material, the tensioning pin 114, laterally inserted inside the middle phalanx 17, abuts against the variable cross-section passively coupled tendon 113. By applying lateral pressure to tension the passively coupled tendon, the initial relaxation is effectively compensated. Furthermore, the flexible hinge joint has a pre-bending angle 116 preset in the initial 3D printing state. This angle provides a stable return torque during repeated finger actuation and resists creep and stress relaxation of the flexible material, ensuring rebound accuracy.

[0052] The present invention also proposes a kinematic modeling method for the universal finger 1, comprising the following steps: S1. Based on the pseudo-rigid body model and the DH parameter method, establish the kinematic coordinate system of the general finger 1 and construct the positive kinematic transfer matrix from the joint configuration space to the fingertip task space. S2. Multimodal calibration measurement: The joint angles of the planar joints under different actuator displacements are collected offline using the visual tracking method; at the same time, the spatial Euler angles of the metacarpophalangeal roll joint 12 and the metacarpophalangeal pitch joint 14 under the dual actuator coupled drive are collected using the IMU inertial measurement unit to obtain dense actuator-joint spatial calibration data. S3. The multinomial regression algorithm is used to fit the actuator-joint spatial calibration data. For the high-dimensional coupled motion of the metacarpophalangeal roll joint 12 and the metacarpophalangeal pitch joint 14, the multinomial regression algorithm is used to establish a nonlinear mapping model to eliminate the hysteresis and cross-coupling effect caused by the deformation of flexible materials. S4. Input the real-time drive displacement of the external drive source into the nonlinear mapping model, and combine it with the positive kinematic transfer matrix to achieve high-fidelity finger end pose estimation, thereby adjusting the drive source output to achieve precise closed-loop control of the dexterous finger.

[0053] Furthermore, refer to Figure 7 The thumb 2 includes a wrist-to-palm joint 21, an interphalangeal joint 23, and a metacarpophalangeal joint 24 connected in sequence. It also includes a wrist-to-palm joint drive rope 22 for driving the wrist-to-palm joint 21, a metacarpophalangeal joint 24 rope for driving the metacarpophalangeal joint 24, and a thumb variable cross-section passive coupling tendon 26 for connecting the interphalangeal joint 23 and the metacarpophalangeal joint 24.

[0054] Specifically, the thumb 2 is laterally positioned on the palm assembly 3 relative to the general finger 1. To adapt to the special spatial constraints of the palm edge and the large range of motion requirements of the thumb 2, the thumb 2 adopts a hybrid transmission structure. The wrist-palm joint 21 at the bottom of the thumb 2 is driven by the wrist-palm joint drive rope 22. The interphalangeal joint 23 and metacarpophalangeal joint 24 inside the thumb 2 achieve mechanical linkage through the passive coupling tendon 26 of the thumb variable cross section.

[0055] In one specific embodiment, refer to Figure 1 A protective sleeve 27 is also provided at the junction of the thumb 2 and the palm component 3.

[0056] Furthermore, refer to Figure 9 The forearm assembly 4 includes an open interface 41 for quick finger replacement, a drive array 42, a PCB circuit board 43, and a wrist interface 44. The proximal ends of the first metacarpophalangeal joint driving tendon 111 and the second metacarpophalangeal joint driving tendon 112 of the general finger 1 are exposed at the open interface 41 to connect with the linear drive unit 5 installed in the forearm assembly 4, so as to achieve modular separation and quick maintenance. The remaining eleven linear drive units 5 place most of their mass at the rear to reduce end-effector rotational inertia. The drive array 42 is composed of the remaining eleven linear drive units 5 arranged in a dense manner. It remotely drives the dexterous hand across the wrist joint by driving tendons 111 and 112 at the first metacarpophalangeal joint of each general finger 1.

[0057] Specifically, the connection between the output nuts 54 of the eleven linear drive units 5 in the forearm assembly 4 and the variable cross-section drive tendon of the universal finger 1 is located on the inner side. When maintenance is required, the operator can quickly disassemble and assemble through this interface, which significantly improves the maintainability of the system.

[0058] Furthermore, refer to Figure 9 and Figure 10The distributed linear drive system includes fifteen linear drive units 5, of which four linear drive units 5 are integrated inside the palm assembly 3, and the remaining eleven linear drive units 5 are disposed inside the forearm assembly 4.

[0059] Specifically, the system's power source is a linear drive unit 5, each of which includes a brushless coreless motor 51, a gear reduction mechanism 52, a trapezoidal lead screw 53, and an output nut 54. During operation, the rotational motion of the brushless coreless motor 51, after torque amplification by the gear reduction mechanism 52, drives the trapezoidal lead screw 53 to rotate, which in turn converts into smooth linear motion of the output nut 54. The proximal end of the variable cross-section driving tendon is directly fixed to the corresponding output nut 54. The output nut 54 moves backward to pull the finger to bend and moves forward to push the finger to straighten.

[0060] Furthermore, refer to Figure 8 Four linear drive units 5 integrated inside the palm assembly 3 drive the proximal interphalangeal joint drive tendons 110 of the four universal fingers 1. The proximal ends of the proximal interphalangeal joint drive tendons 110 are connected to the linear output ends of the corresponding linear drive units 5. The linear drive units 5 apply tension or push force to the proximal interphalangeal joint drive tendons 110 to realize the bending and stable return movements of the corresponding universal fingers 1.

[0061] Furthermore, refer to Figure 9 Eleven linear drive units 5 integrated inside the forearm assembly 4 are used to drive the other joint degrees of freedom of each general finger 1. In order to balance the complexity of the wiring and the rotational inertia of the dexterous hand end, the forearm assembly 4 and the palm assembly 3 are set separately. The eleven linear drive units 5 inside the forearm assembly 4 cross the wrist assembly to remotely drive the general finger 1 and the thumb 2. The eleven linear drive units 5 integrated inside the forearm assembly 4 are divided into a first layer drive unit, a second layer drive unit, and a third layer drive unit from front to back. The first layer drive unit includes four linear drive units 5 arranged side by side, the second layer drive unit includes four linear drive units 5 arranged side by side, and the third layer drive unit includes three linear drive units 5 arranged side by side. The four drive units of the first layer drive unit are respectively connected to the first metacarpophalangeal joint drive tendon 111 of the four universal fingers 1. The four drive units of the second layer drive unit are respectively connected to the second metacarpophalangeal joint drive tendon 112 of the four universal fingers 1. The three drive units of the third layer drive unit are respectively connected to the first carpal joint drive rope 221 on one side of the thumb 2, the second carpal joint drive rope 222 on the other side of the thumb 2, and the metacarpophalangeal joint drive rope 25 of the thumb 2.

[0062] Furthermore, refer to Figure 10 The linear drive unit 5 includes a brushless hollow cup motor 51, a gear reduction mechanism 52, a trapezoidal lead screw 53, and an output nut 54 that cooperates with the trapezoidal lead screw 53; The rotational motion of the brushless hollow cup motor 51 is transmitted to the trapezoidal lead screw 53 via the gear reduction mechanism 52, and is converted into the linear motion of the output nut 54. The output nut 54 is fixedly connected to the proximal end of the variable cross-section driving tendon.

[0063] The above description is merely a preferred embodiment of the present invention. The present invention is not limited to the above-described embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure, as long as they achieve the technical effects of the present invention by the same means, should be included within the scope of protection of this disclosure. Within the scope of protection of the present invention, the technical solutions and / or implementation methods can have various modifications and variations.

Claims

1. A 3D-printed five-fingered dexterous hand based on variable cross-section tendon drive, characterized in that, include: Hand component (3); A universal finger (1), the proximal end of which is connected to the palm assembly (3); The thumb (2) is connected to the proximal end of the palm assembly (3); Forearm assembly (4), the proximal end of the palm assembly (3) is connected to the forearm assembly (4); A distributed linear drive system includes multiple linear drive units (5), which are respectively disposed inside the palm assembly (3) and the forearm assembly (4).

2. The 3D-printed five-fingered dexterous hand based on variable cross-section tendon drive according to claim 1, characterized in that, The palm assembly (3) includes a palm pad layer (31), an intermediate layer (32), and a back cover layer (33). The surface of the palm pad (31) is a high-friction contact surface; The intermediate layer (32) is provided with a tendon guide groove (34) on the side near the palm pad layer (31). The intermediate layer (32) is also provided with a groove on the side near the back cover layer (33), the groove being used to accommodate multiple linear drive units (5) integrated inside the palm assembly (3). The back of the hand cover (33) is a rigid protective plate used to seal the internal structure of the palm assembly (3).

3. The 3D-printed five-fingered dexterous hand based on variable cross-section tendon drive according to claim 1, characterized in that, The universal finger (1) includes a finger base (11), a metacarpophalangeal rotator joint (12), a first proximal phalanx (13), a metacarpophalangeal flexion joint (14), a second proximal phalanx (15), a proximal interphalangeal joint (16), a middle phalanx (17), a distal interphalangeal joint (18), and a distal phalanx (19) connected in sequence. It also includes the proximal interphalangeal joint driving tendon (110), the first metacarpophalangeal joint driving tendon (111), the second metacarpophalangeal joint driving tendon (112), and the variable cross-section passive coupling tendon (113). The first end of the proximal interphalangeal joint driving tendon (110) is connected to the middle phalanx (17), the middle part of the proximal interphalangeal joint driving tendon (110) passes through the second tendon channel built into the second proximal phalanx (15) and the first tendon channel built into the first proximal phalanx (13) in sequence, and the second end of the proximal interphalangeal joint driving tendon (110) extends proximally and connects to an external driving source; The first metacarpophalangeal joint driving tendon (111) and the second metacarpophalangeal joint driving tendon (112) are arranged in parallel. The first ends of the first metacarpophalangeal joint driving tendon (111) and the second metacarpophalangeal joint driving tendon (112) are respectively connected to the second proximal phalanx (15). The second ends of the first metacarpophalangeal joint driving tendon (111) and the second metacarpophalangeal joint driving tendon (112) extend proximally and are respectively connected to an external driving source. The first end of the variable cross-section passive coupling tendon (113) is connected to the distal phalanx (19). The middle part of the cross-section passive coupling tendon passes through the third tendon channel built into the middle phalanx (17) and extends along the surface of the middle phalanx (17) and the surface of the second proximal phalanx (15). The second end of the cross-section passive coupling tendon is connected to the second proximal phalanx (15). The variable cross-section passive coupling tendon (113) is used to mechanically couple the proximal interphalangeal joint (16) and the distal interphalangeal joint (18) to achieve linkage between the proximal interphalangeal joint (16) and the distal interphalangeal joint (18).

4. The 3D-printed five-fingered dexterous hand based on variable cross-section tendon drive according to claim 3, characterized in that, The proximal interphalangeal joint driving tendon (110), the first metacarpophalangeal joint driving tendon (111) and the second metacarpophalangeal joint driving tendon (112) are all variable cross-section driving tendons, and the metacarpophalangeal roll joint (12), the metacarpophalangeal pitch joint (14), the proximal interphalangeal joint (16) and the distal interphalangeal joint (18) are all flexible hinge joints. The proximal interphalangeal joint driving tendon (110), the first metacarpophalangeal joint driving tendon (111), and the second metacarpophalangeal joint driving tendon (112) have varying cross-sectional dimensions along their respective length directions. In the bending regions corresponding to the metacarpophalangeal roll joint (12), metacarpophalangeal pitch joint (14), proximal interphalangeal joint (16) and distal interphalangeal joint (18), the thickness of the proximal interphalangeal joint driving tendon (110), the first metacarpophalangeal joint driving tendon (111) and the second metacarpophalangeal joint driving tendon (112) is reduced to provide maximum flexibility. In the weak bending region outside the plane of the corresponding metacarpophalangeal roll joint (12), metacarpophalangeal pitch joint (14), proximal interphalangeal joint (16) and distal interphalangeal joint (18), the thickness of the proximal interphalangeal joint driving tendon (110), the first metacarpophalangeal joint driving tendon (111) and the second metacarpophalangeal joint driving tendon (112) is increased to improve flexion resistance.

5. The 3D-printed five-fingered dexterous hand based on variable cross-section tendon drive according to claim 1, characterized in that, The thumb (2) includes a carpal joint (21), an interphalangeal joint (23) and a metacarpophalangeal joint (24) connected in sequence, and also includes a carpal joint drive rope (22) for driving the carpal joint (21), a metacarpophalangeal joint (24) rope for driving the metacarpophalangeal joint (24), and a thumb variable cross section passive coupling tendon (26) for connecting the interphalangeal joint (23) and the metacarpophalangeal joint (24).

6. The 3D-printed five-fingered dexterous hand based on variable cross-section tendon drive according to claim 1, characterized in that, The forearm assembly (4) includes an open interface (41) for quick finger replacement, a drive array (42), a PCB circuit board (43) and a wrist interface (44). The proximal ends of the first metacarpophalangeal joint driving tendon (111) and the second metacarpophalangeal joint driving tendon (112) of the universal finger (1) and the connection end of the linear drive unit (5) installed in the forearm assembly (4) are exposed at the open interface (41) to achieve modular separation and quick maintenance. The remaining eleven linear drive units (5) have most of their mass rearward to reduce end-effector rotational inertia. The drive array (42) is composed of the remaining eleven linear drive units (5) arranged in a dense manner. The drive tendons (111) and (112) of the first metacarpophalangeal joints of each general finger (1) remotely drive the dexterous hand across the wrist joint.

7. The 3D-printed five-fingered dexterous hand based on variable cross-section tendon drive according to claim 1, characterized in that, The distributed linear drive system includes fifteen linear drive units (5), of which four linear drive units (5) are integrated inside the palm assembly (3), and the remaining eleven linear drive units (5) are disposed inside the forearm assembly (4).

8. The 3D-printed five-fingered dexterous hand based on variable cross-section tendon drive according to claim 7, characterized in that, Four linear drive units (5) integrated inside the palm assembly (3) drive the proximal interphalangeal joint drive tendons (110) of the four universal fingers (1). The proximal ends of the proximal interphalangeal joint drive tendons (110) are connected to the linear output ends of the corresponding linear drive units (5). The linear drive units (5) apply tension or push force to the proximal interphalangeal joint drive tendons (110) to realize the bending and stable return movements of the corresponding universal fingers (1).

9. The 3D-printed five-fingered dexterous hand based on variable cross-section tendon drive according to claim 7, characterized in that, Eleven linear drive units (5) integrated inside the forearm assembly (4) are used to drive the other joint degrees of freedom of each universal finger (1). In order to balance the complexity of the wiring and the rotational inertia of the dexterous hand end, the forearm assembly (4) and the palm assembly (3) are set separately. The eleven linear drive units (5) inside the forearm assembly (4) cross the wrist assembly to remotely drive the universal finger (1) and the thumb (2). The eleven linear drive units (5) integrated inside the forearm assembly (4) are divided into a first layer drive unit, a second layer drive unit and a third layer drive unit from front to back. The first layer drive unit includes four linear drive units (5) arranged side by side, the second layer drive unit includes four linear drive units (5) arranged side by side, and the third layer drive unit includes three linear drive units (5) arranged side by side. The four drive units of the first layer drive unit are respectively connected to the first metacarpophalangeal joint drive tendon (111) of the four universal fingers (1), the four drive units of the second layer drive unit are respectively connected to the second metacarpophalangeal joint drive tendon (112) of the four universal fingers (1), and the three drive units of the third layer drive unit are respectively connected to the first carpal joint drive rope (221) on one side of the thumb (2), the second carpal joint drive rope (222) on the other side of the thumb (2) and the metacarpophalangeal joint drive rope (25) of the thumb (2).

10. The 3D-printed five-fingered dexterous hand based on variable cross-section tendon drive according to claim 1, characterized in that, The linear drive unit (5) includes a brushless hollow cup motor (51), a gear reduction mechanism (52), a trapezoidal lead screw (53), and an output nut (54) that cooperates with the trapezoidal lead screw (53). The rotational motion of the brushless hollow cup motor (51) is transmitted to the trapezoidal lead screw (53) through the gear reduction mechanism (52), and is converted into the linear motion of the output nut (54). The output nut (54) is fixedly connected to the proximal end of the variable cross-section driving tendon.

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