Multi-degree-of-freedom tendon-driven robot finger

Abstract

The multi-degree-of-freedom tendon-driven robot finger comprises a palm knuckle, a first knuckle, a second knuckle, a third knuckle, a driving device and a tendon rope, and each knuckle comprises a knuckle body and a tendon rope guiding mechanism; the palm knuckles and the first knuckles are connected through first ligaments to form first interphalangeal joints with three degrees of freedom, the first knuckles and the second knuckles are connected through second ligaments to form second interphalangeal joints with single degrees of freedom, and the second knuckles and the third knuckles are connected through third ligaments to form third interphalangeal joints with single degrees of freedom; the tendon ropes comprise the radial side finger bending tendon rope, the ulnar side finger bending tendon rope and the finger stretching tendon rope, the tendon ropes penetrate through the tendon rope guiding mechanism and are connected with the driving device, and the driving device drives the fingers to conduct stretching-bending movement and abduction-adduction movement through the tendon ropes. The finger stretching tendon rope comprises a non-elastic body part used for achieving stretching of a first interphalangeal joint, a first elastic part used for achieving stretching of a second interphalangeal joint and a second elastic part used for achieving stretching of a third interphalangeal joint.

Description

Technical Field

[0001] This invention relates to the field of robot end effector technology, and in particular to a multi-degree-of-freedom tendon-driven robot finger based on a rigid-flexible coupling structure, which has high flexibility and compliance. Background Technology

[0002] For decades, many research institutions at home and abroad have made remarkable achievements in the design and control of robotic dexterous hands in order to simulate and reproduce the functions of human hands. For robotic fingers, which are closely related to the performance of robotic dexterous hands, most technical solutions adopt simple serial pin joint designs and linkage transmissions, which cannot simultaneously achieve the dexterity and compliance close to that of human fingers; some solutions adopt bionic joint designs and tendon-wire transmissions that highly replicate the structure of human fingers, but the joint stability and control precision are insufficient. Summary of the Invention

[0003] In view of this, the present invention proposes a multi-degree-of-freedom tendon-driven robotic finger, which aims to realize a multi-degree-of-freedom bionic robotic finger with flexibility, compliance and high motion repeatability through innovative interphalangeal joint design and connection method, combined with motor-tendon cable drive, so as to solve the problem that existing robotic fingers are difficult to simultaneously achieve the flexibility, compliance, joint stability and structural compactness close to human fingers.

[0004] To address the above problems, the present invention proposes the following technical solution: A multi-degree-of-freedom tendon-driven robotic finger includes: a finger body, a driving device, and tendon ligaments. The finger body includes a palmar phalanx, a first phalanx, a second phalanx, and a third phalanx. Each phalanx includes a phalanx body and a tendon ligament guiding mechanism. The palmar phalanx is connected to the first phalanx by a first ligament to form a first interphalangeal joint. The first phalanx is connected to the second phalanx by a second ligament to form a second interphalangeal joint. The second phalanx is connected to the third phalanx by a third ligament to form a third interphalangeal joint. The first interphalangeal joint has three degrees of freedom. The joints, the second interphalangeal joint and the third interphalangeal joint are single-degree-of-freedom joints; the tendon cords include radial flexor tendon cords, ulnar flexor tendon cords and extensor tendon cords, the tendon cords pass through the tendon cord guide mechanism and are connected to the drive device, the drive device drives the fingers to perform extension-flexion and abduction-adduction movements through the tendon cords; wherein, the extensor tendon cords include a non-elastic main body for achieving extension of the first interphalangeal joint, a first elastic part for achieving extension of the second interphalangeal joint and a second elastic part for achieving extension of the third interphalangeal joint.

[0005] Further, the tendon ligament guiding mechanism includes: a palmar tendon ligament guiding portion located at the proximal end of the palmar phalanx, a first tendon ligament guiding portion located in the middle of the first phalanx, a second tendon ligament guiding portion located in the middle of the second phalanx, and a third tendon ligament guiding portion located at the distal end of the third phalanx; one end of the radial flexor tendon ligament and the ulnar flexor tendon ligament are fixed to the third phalanx, and the other end is connected to the driving device after passing through the second tendon ligament guiding portion, the first tendon ligament guiding portion, and the palmar tendon ligament guiding portion in sequence; one end of the non-elastic main body is fixed to the first phalanx, and the other end is connected to the driving device after passing through the palmar tendon ligament guiding portion; the first elastic portion is located on the dorsal side of the second interphalangeal joint, and its two ends pass over the dorsal side of the first tendon ligament guiding portion and the dorsal side of the second tendon ligament guiding portion respectively before connecting end to end; the second elastic portion is located on the dorsal side of the third interphalangeal joint, and its two ends pass over the dorsal side of the second tendon ligament guiding portion and the dorsal side of the third tendon ligament guiding portion respectively before connecting end to end.

[0006] Furthermore, both the first and second tendon cord guiding portions have guide holes at their proximal and distal ends on the radial and ulnar sides of the palm, respectively, for constraining and guiding the path of the tendon cord. Even further, the guide holes are circular guide holes.

[0007] Furthermore, one end of the radial flexor tendon cord is knotted and sintered after passing over the connecting post between the third tendon cord guide portion and the phalanx body of the third phalanx. The other end passes through the palmar radial guide hole of the second and first tendon cord guide portions, and passes over the palmar radial reversing post of the palmar tendon cord guide portion, before connecting to the first motor of the drive device. One end of the ulnar flexor tendon cord is knotted and sintered after passing over the connecting post between the third tendon cord guide portion and the phalanx body of the third phalanx. The other end passes through the palmar ulnar guide hole of the second and first tendon cord guide portions, and passes over the palmar ulnar reversing post of the palmar tendon cord guide portion, before connecting to the first motor of the drive device. Two motors; one end of the non-elastic main body is knotted and sintered after passing around the connecting post between the first tendon guide part and the phalanx body of the first phalanx, and the other end passes through the guide hole on the back side of the phalanx body of the palm phalanx and passes around the reversing post on the back side of the palm tendon guide part, and is connected to the third motor of the drive device; the first elastic part is a first elastic line, and the two ends of the first elastic line are respectively connected end to end and knotted after passing around the connecting post on the back side of the first tendon guide part and the back side of the second tendon guide part; the second elastic part is a second elastic line, and the two ends of the second elastic line are respectively connected end to end and knotted after passing around the connecting post on the back side of the second tendon guide part and the back side of the third tendon guide part.

[0008] Furthermore, the first interphalangeal joint adopts a ball-and-socket structure, which is a three-degree-of-freedom joint including extension-flexion, abduction-adduction, and external rotation-internal rotation; the second interphalangeal joint and the third interphalangeal joint both adopt a pin-like structure, which are single-degree-of-freedom joints of extension-flexion.

[0009] Furthermore, the first, second, and third ligaments each contain multiple parallel fishing lines; adjacent ends of two adjacent phalanges each have a through hole, and the two ends of each ligament connect end to end after passing through the adjacent through holes, thereby connecting and constraining adjacent phalanges to form an interphalangeal joint. Even further, each ligament contains three parallel high-molecular-weight polyethylene fishing lines, and the diameter of the reserved through hole should be at least the sum of the diameters of the three fishing lines.

[0010] Furthermore, the main body of the palmar knuckle and the guiding part of the palmar tendon are made of aluminum alloy and are manufactured by selective laser melting technology.

[0011] Furthermore, the first, second, and third phalanges are all integrally formed using multi-material fused deposition modeling technology. The main body of each phalange is made of polyethylene terephthalate, and the tendon ligament guiding part is made of thermoplastic polyurethane.

[0012] The beneficial effects of this invention are reflected in the following: the multi-degree-of-freedom tendon-driven robot finger provided by this invention simultaneously possesses high flexibility, compliance, and compactness, as well as high motion repeatability. Specifically, by designing the first interphalangeal joint as a three-degree-of-freedom joint and designing the finger extensor tendon rope as a hybrid structure with a non-elastic main body driving at the proximal joint and an elastic part passively rebounding at the distal joint, the finger simultaneously possesses high flexibility and compliance. With the motor built-in and tendon rope transmission, the three tendon ropes, based on various combinations of coordinated drive, enable one finger of this invention to achieve three active degrees of freedom with only three motors, greatly reducing the number of motors required and improving compactness. In addition, the finger of this invention is driven by two flexor tendon ropes on the left and right sides simultaneously, ensuring that the driven finger does not wobble or deviate when flexing, thereby ensuring high motion repeatability. Ultimately, the finger of this invention can achieve five degrees of freedom (including three active degrees of freedom) of dexterous and compliant movement of a human-like finger, as well as stable and precise grasping function, with fewer drive units (3 motors) and a highly integrated structure, achieving an excellent balance between performance, cost, and size. Attached Figure Description

[0013] Figure 1 This is a front view of the overall structure of a multi-degree-of-freedom tendon-driven robot finger in one embodiment of the present invention.

[0014] Figure 2 yes Figure 1 The image shows a rear view of the overall structure of the finger of a multi-degree-of-freedom tendon-driven robot.

[0015] Figure 3 yes Figure 1 The left view shows the overall structure of the finger of a multi-degree-of-freedom tendon-driven robot. Detailed Implementation

[0016] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the embodiments of the present invention are not limited thereto.

[0017] The present invention aims to provide a specific implementation of a multi-degree-of-freedom tendon-driven robot finger. Its core lies in the innovative joint structure design (the first interphalangeal joint has three degrees of freedom, and the second and third joints have one degree of freedom) and the ingenious tendon-driven scheme, which comprehensively achieves the flexibility, compliance and compactness of the finger, while also ensuring high motion repeatability accuracy.

[0018] Please refer to Figures 1 to 3 This invention provides a multi-degree-of-freedom tendon-driven robot finger, comprising: a finger body, a driving device 7, and tendon ropes 6. The finger body includes a palmar phalanx 1, a first phalanx 2, a second phalanx 3, and a third phalanx 4. Each phalanx includes a phalanx body and a tendon rope guiding mechanism. Adjacent phalanges are connected by ligaments 5 to form interphalangeal joints. The driving device includes three motors 71, 72, and 73. The tendon ropes 6 include a radial flexor tendon rope 61, an ulnar flexor tendon rope 62, and a finger extensor tendon rope 63.

[0019] Please refer to Figure 1 The palmar phalanx 1 includes a phalanx body 11 and a palmar tendon ligament guiding portion 12; the first phalanx 2 includes a phalanx body 21 and a first tendon ligament guiding portion 22; the second phalanx 3 includes a phalanx body 31 and a second tendon ligament guiding portion 32; and the third phalanx 4 includes a phalanx body 41 and a third tendon ligament guiding portion 42. Preferably, the palmar tendon ligament guiding portion 12 is located at the proximal end of the palmar phalanx 1, the first tendon ligament guiding portion 22 is located in the middle of the first phalanx 2, the second tendon ligament guiding portion 32 is located in the middle of the second phalanx 3, and the third tendon ligament guiding portion 42 is located at the distal end of the third phalanx 4. Furthermore, both the first tendon ligament guiding portion 22 and the second tendon ligament guiding portion 32 have guide holes at their proximal and distal ends on the radial and ulnar sides of the palmar side, respectively, allowing the tendon ligament to pass through for restraint and guidance. The guide holes have a depth of 2 mm and a diameter of 1.5 mm.

[0020] Please refer to Figure 3The first interphalangeal joint is formed by ligament 51 connecting the first metacarpal phalanx 1 and the first metacarpal phalanx 2; the second interphalangeal joint is formed by ligament 52 connecting the first metacarpal phalanx 2 and the second metacarpal phalanx 3; and the third interphalangeal joint is formed by ligament 53 connecting the second metacarpal phalanx 3 and the third metacarpal phalanx 4. The first interphalangeal joint has a ball-and-socket structure, providing three degrees of freedom: extension-flexion, abduction-adduction, and external rotation-internal rotation. The second and third interphalangeal joints both have a pin-like structure, providing only one degree of freedom: extension-flexion. Specifically, the two ends of the ligament 51 at the first interphalangeal joint pass through the positioning holes at the base of the first phalanx 2 and the head of the palmar phalanx 1, respectively, and are then tied and sintered on the other side for fixation. The two ends of the ligament 52 at the second interphalangeal joint pass through the positioning holes at the base of the second phalanx 3 and the head of the first phalanx 2, respectively, and are then tied and sintered on the other side for fixation. The two ends of the ligament 53 at the third interphalangeal joint pass through the positioning holes at the base of the third phalanx 4 and the head of the second phalanx 3, respectively, and are then tied and sintered on the other side for fixation.

[0021] Figure 2 This is a rear view of the finger, showing the back side of the finger. (Example:) Figure 2 As shown, in a preferred embodiment, the finger extensor tendon cord 63 includes a non-elastic main body portion 631 and an elastic portion (specifically including a first elastic line 632 and a second elastic line 633), wherein the non-elastic main body portion 631 is located on the dorsal side of the first interphalangeal joint, and the first elastic line 632 and the second elastic line 633 are located on the dorsal sides of the second interphalangeal joint and the third interphalangeal joint, respectively.

[0022] Please refer to Figure 1One end of the radial flexor tendon cord 61 is knotted and sintered after passing over the connecting post between the third tendon cord guide portion 42 and the phalanx body 41 of the third phalanx. The other end passes through the palmar radial guide holes of the second tendon cord guide portion 32 and the first tendon cord guide portion 22, and passes over the palmar radial reversing post of the palmar tendon cord guide portion 12, before being connected to the motor 71. One end of the ulnar flexor tendon cord 62 is knotted and sintered after passing over the connecting post between the third tendon cord guide portion 42 and the phalanx body 41 of the third phalanx. The other end passes through the palmar ulnar guide holes of the second tendon cord guide portion 32 and the first tendon cord guide portion 22, and passes over the palmar ulnar reversing post of the palmar tendon cord guide portion 12, before being connected to the motor 72. One end of the non-elastic main body 631 of the finger extensor tendon cord 63 is knotted and sintered after passing around the connecting post between the first tendon cord guide part 22 and the phalanx body 21 of the first phalanx. The other end passes through the guide hole on the back side of the phalanx body 11 of the palm phalanx and passes around the reversing post on the back side of the palm tendon cord guide part 12, and is connected to the motor 73. The two ends of the first elastic line 632 are respectively connected end to end and knotted after passing around the connecting post on the back side of the first tendon cord guide part 22 and the back side of the second tendon cord guide part 32. The two ends of the second elastic line 633 are respectively connected end to end and knotted after passing around the connecting post on the back side of the second tendon cord guide part 32 and the back side of the third tendon cord guide part 42.

[0023] Motors 71 and 72 drive the first interphalangeal joint to flex via radial flexor tendon cord 61 and ulnar flexor tendon cord 62, and motor 73 drives the first interphalangeal joint to extend via the inelastic body portion 631 of the extensor tendon cord. When motor 73 restricts the flexion of the first interphalangeal joint via the inelastic body portion 631 of the extensor tendon cord, motors 71 and 72 drive the second and third interphalangeal joints to flex via radial flexor tendon cord 61 and ulnar flexor tendon cord 62, and the second and third interphalangeal joints are extended via the first elastic cord 632 and the second elastic cord 633. When motor 73 restricts the flexion of the first interphalangeal joint via the inelastic body portion 631 of the extensor tendon cord, motor 71 drives the first interphalangeal joint to abduct via radial flexor tendon cord 61, and motor 72 drives the first interphalangeal joint to adduct via ulnar flexor tendon cord 62.

[0024] In some specific embodiments of the present invention, adjacent ends of two adjacent phalanges are respectively provided with through holes, and the two ends of each ligament are connected end to end after passing through the adjacent through holes, thereby connecting and constraining adjacent phalanges to form interphalangeal joints. In an exemplary implementation, the ligaments connecting the phalanges are three parallel high molecular weight polyethylene fishing lines, and the diameter of the reserved through holes should be at least the sum of the diameters of the three fishing lines, preferably slightly larger than the sum of the diameters of the three parallel fishing lines. In a specific embodiment of the present invention using three parallel high molecular weight polyethylene fishing lines, a through hole with a diameter of 2 mm is reserved. In addition, the radial flexor tendon rope 61 and the ulnar flexor tendon rope 62 are both implemented using a single high molecular weight polyethylene fishing line; the non-elastic main body of the extensor tendon rope 63 uses the same high molecular weight polyethylene fishing line as the flexor tendon rope, while the elastic part uses thermoplastic polyurethane elastic thread.

[0025] In an exemplary embodiment of the present invention, the phalanx body 11 and the palm tendon tract guide portion 12 of the palm phalanx 1 are made of aluminum alloy and are manufactured by selective laser melting (SLM) technology; the first phalanx 2, the second phalanx 3 and the third phalanx 4 are all integrally formed by fused deposition modeling (FDM) technology, wherein their phalanx body portions are all made of polyethylene terephthalate (PETG) material, and their tendon tract guide portions are all made of thermoplastic polyurethane (TPU) material.

[0026] The multi-degree-of-freedom tendon-driven robot finger provided in the foregoing embodiments of the present invention combines the advantages of traditional pin joints and bionic joints in terms of joint design, and innovatively optimizes the tendon-driven path, bringing the following technical advantages: 1. This invention can reproduce the five degrees of freedom of a human finger, of which the first interphalangeal joint has three degrees of freedom, thereby achieving the flexibility and suppleness of a human finger; 2. When the two palmar tendons (radial flexor tendon 61 and ulnar flexor tendon 62) drive finger flexion simultaneously, high repetitive motion accuracy can be ensured. 3. Based on the optimized tendon drive path design, three sets of motor-tendon cable drives can achieve three active degrees of freedom, thereby making the overall structure, including the drive part, more compact.

[0027] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, several equivalent substitutions or obvious modifications can be made without departing from the concept of the present invention, and all such modifications, achieving the same performance or purpose, should be considered within the scope of protection of the present invention.

Claims

1. A multi-degree-of-freedom tendon-driven robotic finger, characterized in that, include: The finger body comprises a finger body, a drive mechanism, and a tendon cord. The finger body includes a palmar phalanx (1), a first phalanx (2), a second phalanx (3), and a third phalanx (4). Each phalanx includes a phalanx body and a tendon cord guiding mechanism. The palmar phalanx is connected to the first phalanx by a first ligament (51) to form a first interphalangeal joint. The first phalanx is connected to the second phalanx by a second ligament (52) to form a second interphalangeal joint. The second phalanx is connected to the third phalanx by a third ligament (53) to form a third interphalangeal joint. The first interphalangeal joint is a three-degree-of-freedom joint, while the second and third interphalangeal joints are single-degree-of-freedom joints. The tendon cords include radial flexor tendon cords (61), ulnar flexor tendon cords (62), and extensor tendon cords (63). The tendon cords pass through the tendon cord guide mechanism and are connected to the drive device. The drive device drives the fingers to perform extension-flexion and abduction-adduction movements through the tendon cords. The extensor tendon cord (63) includes a non-elastic main body (631) for achieving extension of the first interphalangeal joint, a first elastic part (632) for achieving extension of the second interphalangeal joint, and a second elastic part (633) for achieving extension of the third interphalangeal joint.

2. The multi-degree-of-freedom tendon-driven robotic finger as described in claim 1, characterized in that, The tendon ligament guiding mechanism includes: a palm tendon ligament guiding portion (12) located at the proximal end of the palm phalanx (1), a first tendon ligament guiding portion (22) located in the middle of the first phalanx (2), a second tendon ligament guiding portion (32) located in the middle of the second phalanx (3), and a third tendon ligament guiding portion (42) located at the distal end of the third phalanx (4). One end of the radial flexor tendon cord (61) and the ulnar flexor tendon cord (62) are fixed to the third phalanx (4), and the other end is connected to the drive device after passing through the second tendon cord guide portion (32), the first tendon cord guide portion (22) and the palm tendon cord guide portion (12) in sequence. One end of the non-elastic main body (631) is fixed to the first phalanx (2), and the other end is connected to the drive device via the palm tendon guide part (12); The first elastic portion (632) is located on the dorsal side of the second interphalangeal joint, and its two ends pass over the dorsal side of the first tendon rope guide portion (22) and the dorsal side of the second tendon rope guide portion (32) respectively and then connect end to end; the second elastic portion (633) is located on the dorsal side of the third interphalangeal joint, and its two ends pass over the dorsal side of the second tendon rope guide portion (32) and the dorsal side of the third tendon rope guide portion (42) respectively and then connect end to end.

3. The multi-degree-of-freedom tendon-driven robotic finger as described in claim 2, characterized in that, The first tendon cord guiding portion (22) and the second tendon cord guiding portion (32) are provided with guide holes at the proximal and distal ends of the palmar radial side and palmar ulnar side, respectively, for constraining and guiding the path of the tendon cord.

4. The multi-degree-of-freedom tendon-driven robotic finger as described in claim 3, characterized in that, The guide hole is a guide circular hole.

5. The multi-degree-of-freedom tendon-driven robotic finger as described in claim 3, characterized in that, One end of the radial flexor tendon cord (61) passes around the connecting post between the third tendon cord guide part (42) and the phalanx body of the third phalanx, is knotted and sintered to fix it, and the other end passes through the palmar radial guide hole of the second tendon cord guide part (32) and the first tendon cord guide part (22), and passes around the palmar radial reversing post of the palmar tendon cord guide part (12), and is connected to the first motor (71) of the drive device. One end of the ulnar flexor tendon cord (62) passes around the connecting post between the third tendon cord guide part (42) and the phalanx body of the third phalanx, is knotted and sintered to fix it, and the other end passes through the palmar ulnar guide hole of the second tendon cord guide part (32) and the first tendon cord guide part (22), and passes around the palmar ulnar reversing post of the palmar tendon cord guide part (12), and is connected to the second motor (72) of the drive device. One end of the non-elastic main body (631) is knotted and sintered after passing around the connecting post between the first tendon guide part (22) and the phalanx body of the first phalanx. The other end passes through the guide hole on the back side of the phalanx body of the palm phalanx and passes around the reversing post on the back side of the palm tendon guide part (12), and is connected to the third motor (73) of the drive device. The first elastic part (632) is a first elastic line. The two ends of the first elastic line are connected end to end and knotted after wrapping around the proximal end of the back side of the first tendon rope guide part (22) and the connecting post on the back side of the second tendon rope guide part (32). The second elastic part (633) is a second elastic line. The two ends of the second elastic line are connected end to end and knotted after wrapping around the connecting post on the back side of the second tendon guide part (32) and the back side of the third tendon guide part (42).

6. The multi-degree-of-freedom tendon-driven robotic finger as described in any one of claims 1 to 5, characterized in that, The first interphalangeal joint adopts a ball-and-socket structure and is a three-degree-of-freedom joint including extension-flexion, abduction-adduction, and external rotation-internal rotation; the second and third interphalangeal joints both adopt a pin-like structure and are single-degree-of-freedom joints of extension-flexion.

7. The multi-degree-of-freedom tendon-driven robotic finger as described in any one of claims 1 to 5, characterized in that, The first ligament (51), the second ligament (52) and the third ligament (53) each contain multiple parallel fishing lines; the adjacent ends of two adjacent phalanges are respectively reserved with through holes, and the two ends of each ligament are connected end to end after passing through the adjacent through holes, thereby connecting and constraining the adjacent phalanges to form an interphalangeal joint.

8. The multi-degree-of-freedom tendon-driven robotic finger as described in claim 7, characterized in that, Each ligament contains three parallel high molecular weight polyethylene fishing lines, and the diameter of the reserved through hole should be at least the sum of the diameters of the three fishing lines.

9. The multi-degree-of-freedom tendon-driven robotic finger as described in any one of claims 1 to 5, characterized in that, The main body of the palmar phalanx and the palmar tendon guide part (12) are made of aluminum alloy and are manufactured by selective laser melting technology.

10. The multi-degree-of-freedom tendon-driven robotic finger as described in any one of claims 1 to 5, characterized in that, The first phalanx (2), the second phalanx (3) and the third phalanx (4) are all integrally formed by multi-material fused deposition modeling technology. The main body of the three phalanxes is made of polyethylene terephthalate, and the tendon ligament guiding part is made of thermoplastic polyurethane.

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