One-degree-of-freedom finger structure

Abstract

The utility model relates to the technical field of manipulators, in particular to a one-degree-of-freedom finger structure which comprises an actuator and a finger joint assembly, the actuator comprises an output end moving along a straight line, a connecting tool is fixedly arranged at the end of the actuator, and the output end penetrates through the connecting tool; a first connecting part is fixedly arranged on the connecting tool, and the first connecting part is located on one side of the output end; the finger joint assembly comprises a first connecting rod, a second connecting rod, a fingertip seat, a transmission connecting rod, a first coupling connecting rod and a second coupling connecting rod, and a second connecting part is fixedly arranged on the fingertip seat. In order to solve the technical problem that an existing mechanical finger structure has defects, output of a single actuator is used as power, and a multi-connecting-rod mechanism is designed to serve as a main body of the finger structure, so that anthropomorphic natural bending of fingers is achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of manipulators, in particular to a finger structure with one degree of freedom. Background Art

[0002] Some traditional robot end effectors (i.e., manipulators) have design limitations on their palm and finger structures, resulting in a single overall grasping method and lack of flexibility.

[0003] For example, the flexibility of an anthropomorphic robotic hand is primarily limited by the structure of its fingers. Achieving the same bending dexterity as a human finger requires complex structural design for the finger joints, and each joint requires a separate drive mechanism. This results in excessive complexity and extremely high design, manufacturing, and assembly costs. Utility Model Content

[0004] In response to the technical problems of defects in existing mechanical finger structures, the utility model provides a one-degree-of-freedom finger structure, which uses the output of a single actuator as power and designs a multi-link mechanism as the main body of the finger structure, thereby realizing anthropomorphic natural bending of the finger.

[0005] The technical solution provided by the utility model is: a one-degree-of-freedom finger structure, including an actuator and a finger joint assembly; the actuator includes an output end that moves along a straight line, and the end of the actuator is fixedly provided with a connecting tooling, and the output end passes through the connecting tooling; a first connecting part is fixedly provided on the connecting tooling, and the first connecting part is located on one side of the output end; the finger joint assembly includes a first connecting rod, a second connecting rod, a fingertip seat, a transmission connecting rod, a first coupling connecting rod and a second coupling connecting rod, and a second connecting part is fixedly provided on the fingertip seat; the first connecting rod and the first connecting part are hinged to form a first rotation pair R1, the second connecting rod and the first connecting rod are hinged to form a second rotation pair R2, and the second connecting rod and the second connecting part are hinged to form a third rotation pair R3. When the finger joint assembly is fully stretched, the rotation center lines of the first rotation pair R1, the second rotation pair R2 and the third rotation pair R3 are parallel and coplanar. ; A first extension is provided on the side of the first connecting rod facing the output end, and two ends of the transmission connecting rod are hinged to the output end and the first extension respectively; a second extension is fixedly provided on the side of the first connecting portion facing the output end, and a third extension is fixedly provided on the second connecting rod at a position close to the second rotating pair R2, and the third extension is located on the side of the second connecting rod away from the output end, and the two ends of the first coupling connecting rod are hinged to the second extension and the third extension respectively; a fourth extension is fixedly provided on the first connecting rod at a position close to the second rotating pair R2, and the fourth extension is located on the side of the first connecting rod facing the output end; a fifth extension is fixedly provided on the fingertip seat, and the fifth extension is located on the side of the second connecting portion away from the output end; the two ends of the second coupling connecting rod are hinged to the fourth extension and the fifth extension respectively.

[0006] Optionally, the transmission connecting rod is in an arc shape, and the concave side of the arc-shaped transmission connecting rod faces the first connecting rod.

[0007] Optionally, there is a bend on the first coupling link near the first rotation pair R1 and the second rotation pair R2, and there is a bend on the second coupling link near the second rotation pair R2 and the third rotation pair R3.

[0008] Optionally, contoured covering pieces are fixedly provided on the outer sides of the first connecting rod, the second connecting rod and the fingertip seat.

[0009] Optionally, the length of the first connecting rod is greater than the length of the second connecting rod, and the length of the second connecting rod is greater than the length of the fingertip seat.

[0010] Optionally, the actuator includes a housing, in which a planetary roller screw pair and a motor are arranged; the planetary roller screw pair includes a nut, a screw, a roller and a cage, the nut is arranged on the outside of the screw, and a plurality of rollers are arranged around the screw and the nut, the rollers are respectively engaged with the nut and the screw, and the output end is fixedly connected to the nut; the cage is located between the nut and the screw, and the two ends of the rollers are respectively rotatably connected to the cage; the motor includes a stator and a rotor, the stator is arranged on the outside of the rotor and fixedly connected to the housing, and the screw is fixedly connected to the rotor; a spherical bearing is provided at one end of the actuator, and a tension and pressure sensor is provided on the end of the housing close to the spherical bearing, a rotary encoder is provided between the screw and the housing, a linear displacement sensor is provided between the output end and the inner wall of the housing, a control unit is provided in the housing, and the motor, linear displacement sensor, rotary encoder and tension and pressure sensor are all electrically connected to the control unit.

[0011] Optionally, the roller includes a first meshing section and a second meshing section, the middle diameter of the first meshing section is larger than the middle diameter of the second meshing section, the first meshing section meshes with a portion of the external thread of the lead screw, and the second meshing section meshes with the internal thread of the nut; the lead screw and the nut have the same number of thread heads, the thread profiles of the lead screw and the nut are both triangular, the lead of the threads on the first meshing section and the second meshing section is zero, and the thread profiles on the first meshing section and the second meshing section are semicircular.

[0012] Optionally, a sheath is fixedly provided on the outer side of the nut, and the sheath is used to abut against the inner wall of the shell.

[0013] Optionally, the linear displacement sensor includes a first reading unit and a magnetic grating, the magnetic grating is fixedly arranged on the outside of the nut, the first reading unit is fixedly arranged on the inside of the shell, the first reading unit is arranged opposite to the magnetic grating, and the first reading unit is electrically connected to the control unit.

[0014] Optionally, the rotary encoder includes a second reading unit and a magnetic pole, a magnet sheath is fixedly provided at one end of the lead screw, the magnetic pole is fixedly provided on the magnet sheath, the magnetic pole is arranged opposite to the second reading unit, and the second reading unit is electrically connected to the control unit.

[0015] Beneficial effects

[0016] The technical solution provided by the present invention has the following beneficial effects compared with the existing technology: in response to the technical problem of defects in the existing mechanical finger structure, the present invention uses the output of a single actuator as power and designs a multi-link mechanism as the main body of the finger structure, thereby realizing the anthropomorphic natural bending of the fingers. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a structural schematic diagram of a 1-DOF finger structure proposed in an embodiment of the present utility model.

[0018] Figure 2 This is one of the structural schematic diagrams of the finger joint assembly proposed in an embodiment of the present utility model.

[0019] Figure 3 This is the second structural diagram of the finger joint assembly proposed in an embodiment of the present utility model.

[0020] Figure 4 This is the third structural diagram of the finger joint assembly proposed in an embodiment of the present utility model.

[0021] Figure 5 This is a schematic diagram of the movement principle of the finger joint assembly proposed in an embodiment of the present utility model.

[0022] Figure 6 This is a structural diagram of the actuator proposed in an embodiment of the present utility model. DETAILED DESCRIPTION

[0023] In order to further understand the content of the present invention, the present invention is described in detail with reference to the accompanying drawings and embodiments.

[0024] The present application will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific examples described herein are intended solely to illustrate the relevant utility model and are not intended to limit the utility model. It should also be noted that, for ease of description, only the relevant portions of the utility model are shown in the accompanying drawings. Terms such as "first," "second," and so on, used in the present utility model are provided for the convenience of describing the technical solution of the present utility model and do not have a specific limiting effect. They are general references and do not constitute a limitation on the technical solution of the present utility model. It should be noted that, unless conflicting, the embodiments and features within the embodiments of the present application may be combined with one another. In the description of the present utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating positions or locations, are based on the positions or locations shown in the accompanying drawings and are intended solely to facilitate the description of the present utility model and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting the present utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Unless otherwise expressly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be a communication between the internal parts of two components. For those of ordinary skill in the art, the specific meanings of the above terms in this utility model can be understood according to the specific circumstances. Multiple technical solutions in the same embodiment, as well as multiple technical solutions in different embodiments, can be arranged and combined to form new technical solutions that do not contain contradictions or conflicts, and all of these are within the scope of protection claimed by this utility model.

[0025] Example 1

[0026] Combined with attachment Figure 1-5 , this embodiment proposes a 1-DOF finger structure, including an actuator 2 and a finger joint assembly 1.

[0027] Actuator 2 includes an output end 21 that moves linearly. In this embodiment, actuator 2 preferably employs a planetary roller screw micro linear actuator, with output end 21 typically secured to the translational motion component of the planetary roller screw micro linear actuator. In other embodiments, actuator 2 may also be a micro linear motor, micro electric push rod, or the like.

[0028] In this embodiment, a connecting fixture 22 is fixedly provided at the end of the actuator 2, and the output end 21 passes through the connecting fixture 22. A first connecting portion 23 is fixedly provided on the connecting fixture 22, and the first connecting portion 23 is located on one side of the output end 21.

[0029] The finger joint assembly 1 includes a first connecting rod 11 , a second connecting rod 12 , a fingertip seat 13 , a transmission connecting rod 14 , a first coupling connecting rod 15 and a second coupling connecting rod 16 . A second connecting portion 131 is fixedly provided on the fingertip seat 13 .

[0030] The first connecting rod 11 is hingedly connected to the first connecting portion 23 to form a first rotational pair R1, the second connecting rod 12 is hingedly connected to the first connecting rod 11 to form a second rotational pair R2, and the second connecting rod 12 is hingedly connected to the second connecting portion 131 to form a third rotational pair R3. In other words, in this embodiment, the first connecting rod 11, the second connecting rod 12, and the fingertip seat 13 constitute the "skeleton" portion of the finger joint assembly 1, which can simulate the bending of the three knuckles of a human finger.

[0031] In this embodiment, when the finger joint assembly 1 is fully extended, the rotational centerlines of the first, second, and third rotational pairs R1, R2, and R3 are parallel and coplanar. This is intended to simplify the structure, ensure bending flexibility, and reduce design difficulty, facilitating analysis of the relative motion relationship between the first connecting rod 11, the second connecting rod 12, and the fingertip seat 13 during design, while also ensuring that the finger joint assembly 1 is as consistent with the human finger in terms of form as possible.

[0032] In this embodiment, a first extension portion 111 is provided on the side of the first connecting rod 11 facing the output end 21, and both ends of the transmission connecting rod 14 are hingedly connected to the output end 21 and the first extension portion 111, respectively. In other words, the linear motion of the output end 21 can drive the first connecting rod 11 to swing relative to the first connecting portion 23 through the connection between the transmission connecting rod 14 and the first extension portion 111.

[0033] In this embodiment, a second extension portion 231 is fixedly provided on the side of the first connecting portion 23 facing the output end 21, and a third extension portion 121 is fixedly provided on the second connecting rod 12 at a position close to the second rotating pair R2. The third extension portion 121 is located on the side of the second connecting rod 12 away from the output end 21, and the two ends of the first coupling link 15 are hinged to the second extension portion 231 and the third extension portion 121 respectively.

[0034] A fourth extension portion 112 is fixedly provided on the first connecting rod 11 at a position close to the second rotation pair R2, and the fourth extension portion 112 is located on the side of the first connecting rod 11 facing the output end 21; a fifth extension portion 132 is fixedly provided on the fingertip seat 13, and the fifth extension portion 132 is located on the side of the second connecting portion 131 away from the output end 21; the two ends of the second coupling link 16 are hinged to the fourth extension portion 112 and the fifth extension portion 132 respectively.

[0035] The arrangement of the first coupling link 15 and the second coupling link 16 can play a role similar to that of "tendons" or "muscles", and can further transmit the swing of the first link 11 relative to the first connecting part 23 to the second link 12 and the fingertip seat 13, so that the finger joint assembly 1 can achieve anthropomorphic flexible bending or stretching.

[0036] The following is combined with Figure 5 To further illustrate the operating principle of the one-degree-of-freedom finger structure of this embodiment: Initially, the finger joint assembly 1 is in a vertically extended position, and the output end 21 of the actuator 2 is also at the initial stage of its travel. When the finger joint assembly 1 needs to bend, the output end 21 of the actuator 2 moves linearly outward from the actuator 2. This, through the transmission link 14 and the first extension 111, pushes the first connecting rod 11 to swing away from the output end 21.

[0037] During the swinging of the first link 11, the first coupling link 15 connected to the second extension portion 231 and the third extension portion 121 will drive the second link 12 to swing, that is, the second link 12 will swing relative to the first link 11, and at this time the swinging direction of the second link 12 is consistent with the swinging direction of the first link 11.

[0038] During the swinging of the second connecting rod 12, the second coupling connecting rod 16 connected to the fourth extension part 112 and the fifth extension part 132 will drive the fingertip seat 13 to swing, that is, the fingertip seat 13 will swing relative to the second connecting rod 12, and at this time the swinging direction of the fingertip seat 13 is consistent with the swinging direction of the first connecting rod 11 and the second connecting rod 12.

[0039] Thus, the finger joint assembly 1 of this embodiment eventually transitions from a vertically extended state to a bent state. This bending and stretching movement is defined as one degree of freedom in this embodiment. It is conceivable that the degree of bending of the finger joint assembly 1 can be changed by controlling the stroke of the output end 21 of the actuator 2.

[0040] In summary, the finger joint assembly 1 of this embodiment uses a single actuator 2 as a power source and realizes the anthropomorphic natural bending and extension of the one-degree-of-freedom finger structure through the transmission connection of a multi-link mechanism.

[0041] In this embodiment, the first connecting rod 11, the second connecting rod 12, the fingertip seat 13, the transmission connecting rod 14, the first coupling connecting rod 15 and the second coupling connecting rod 16 should preferably be arranged as shown in the attached figure. Figure 3-4 The symmetrical form shown, that is, the transmission link 14, the first coupling link 15 and the second coupling link 16 should be symmetrically arranged on both sides of the first link 11, the second link 12 and the fingertip seat 13, respectively, to ensure the stability of the transmission.

[0042] To simulate the bending of a human finger as closely as possible, in a preferred embodiment, the length of the first connecting rod 11 is greater than the length of the second connecting rod 12, and the length of the second connecting rod 12 is greater than the length of the fingertip seat 13. As a result, the swing angle of the second connecting rod 12 can be slightly greater than the swing angle of the first connecting rod 11, and the swing angle of the fingertip seat 13 can also be slightly greater than the swing angle of the second connecting rod 12.

[0043] To ensure smooth transmission of the finger joint assembly 1, in a preferred embodiment, the transmission link 14 is arc-shaped, with the concave side of the arc-shaped transmission link 14 facing the first connecting rod 11. As a result, when the output end 21 of the actuator 2 is extended or retracted, the transmission link 14 can more smoothly transmit the thrust, avoid obstruction, and thus more smoothly drive the first connecting rod 11 to swing.

[0044] Furthermore, in another embodiment, a bend is formed on the first coupling link 15 near the first rotational pair R1 and the second rotational pair R2, and a bend is formed on the second coupling link 16 near the second rotational pair R2 and the third rotational pair R3. In this embodiment, the bends on the first coupling link 15 and the second coupling link 16 can also improve the transmission effect and avoid blockage or interference.

[0045] In addition, as attached Figure 1 In one embodiment, contoured covers 17 are fixedly mounted on the outer sides of the first link 11, the second link 12, and the fingertip base 13. In this embodiment, the provision of contoured covers 17 not only enhances the appearance of the 1-DOF finger structure, making it more realistic, but also protects the finger joint assembly 1. Furthermore, the material of contoured covers 17 can be used to modify surface adhesion and friction, thereby improving the performance of the 1-DOF finger structure when used in a robotic hand.

[0046] Example 2

[0047] Combined with attachment Figure 6 Compared with the technical solution of Example 1, the one-degree-of-freedom finger structure of this embodiment can be improved as follows: the actuator 2 includes a housing 20, and a planetary roller screw pair and a motor are arranged in the housing 20.

[0048] Among them, the planetary roller screw pair includes a nut 24, a screw 25, rollers 26 and a retaining frame 27. The nut 24 is arranged on the outside of the screw 25, and a number of rollers 26 are arranged around the screw 25 and the nut 24. The rollers 26 are respectively engaged with the nut 24 and the screw 25, and the output end 21 is fixedly connected to the nut 24.

[0049] The cage 27 is located between the nut 24 and the screw 25, and the two ends of the roller 26 are respectively connected to the cage 27. In this embodiment, the arrangement of the cage 27 can be used to ensure the stability of the arrangement of the roller 26, and can ensure that the planetary roller screw pair moves efficiently, accurately and stably.

[0050] The motor includes a stator 28 and a rotor 29 . The stator 28 is disposed outside the rotor 29 and fixedly connected to the housing 20 . The lead screw 25 is fixedly connected to the rotor 29 .

[0051] A spherical bearing 30 is provided at one end of the actuator 2, a tension and pressure sensor is provided at the end of the housing 20 close to the spherical bearing 30, a rotary encoder is provided between the screw 25 and the housing 20, a linear displacement sensor is provided between the output end 21 and the inner wall of the housing 20, and a control unit 31 is provided in the housing 20. The motor, linear displacement sensor, rotary encoder and tension and pressure sensor are all electrically connected to the control unit 31.

[0052] The planetary roller screw pair of this embodiment has threads machined into its nut 24 and threads machined into its lead screw 25. Combined with the aforementioned structural form, the main operating principle of the actuator 2 of this embodiment is as follows: the control unit 31 controls the motor to drive the lead screw 25 in the planetary roller screw pair to rotate. The nut 24 in the planetary roller screw pair converts the rotational motion of the lead screw 25 into linear motion, driving the output end 21 to translate, thereby achieving linear motion output.

[0053] The movement of the lead screw 25 is controlled by a motor, which is in turn controlled by a control unit 31. A rotary encoder on the control unit 31 outputs the number of revolutions of the lead screw 25 to the control unit 31. A linear displacement sensor outputs the linear movement of the nut 24 to the control unit 31. The tension and pressure sensor outputs the applied tension and pressure to the control unit 31. Because the rotary encoder and linear displacement sensor are co-located on the lead screw 25, they operate synchronously, and both utilize absolute value control. Thus, the control unit 31 combines the input information from the rotary encoder, linear displacement sensor, and tension and pressure sensor to control the movement of the output terminal 21 of the actuator 2.

[0054] In a preferred embodiment, roller 26 includes a first meshing segment 261 and a second meshing segment 262. The median diameter of first meshing segment 261 is larger than that of second meshing segment 262. First meshing segment 261 meshes with the external threads located on a portion of lead screw 25, while second meshing segment 262 meshes with the internal threads of nut 24. Thus, lead screw 25, roller 26, and nut 24 form a differential planetary roller screw, ensuring the precision and stability of actuator 2.

[0055] Furthermore, in a further embodiment, the screw 25 and nut 24 have the same number of thread starts, and both have triangular thread profiles. Furthermore, the threads on the first and second meshing segments 261, 262 have a zero lead, i.e., annular threads, and the thread profiles on the first and second meshing segments 261, 262 are semicircular. This creates a differential planetary roller screw pair that effectively reduces the lead, improving load capacity while making the actuator 2's transmission structure more compact and increasing energy density.

[0056] In this embodiment, the motor is preferably a frameless torque motor. The motor's stator 28 drives the motor's rotor 29, which in turn rotates the lead screw 25, thereby driving the nut 24 in linear motion. Specifically, the motor rotor 29 is directly fixed to the lead screw 25, achieving a direct connection with the lead screw 25. This effectively eliminates the need for an intermediate gear reduction mechanism, significantly improving the structural integration while reducing costs.

[0057] In other embodiments, a sheath 32 is fixedly disposed on the outside of the nut 24. The sheath 32 is configured to abut against the inner wall of the housing 20, that is, the sheath 32 is configured to directly slide and rub against the housing 20, thereby protecting the nut 24. The sheath 32 is preferably made of a non-metallic material such as plastic to reduce the friction coefficient, reduce energy consumption, and improve transmission efficiency.

[0058] In this embodiment, a linear displacement sensor is disposed between the nut 24 and the housing 20. In a preferred embodiment, the linear displacement sensor includes a first reading unit 33 and a magnetic grid 34. The magnetic grid 34 is fixedly disposed on the outside of the sheath 32, and the first reading unit 33 is fixedly disposed on the inside of the housing 20. The first reading unit 33 and the magnetic grid 34 are disposed opposite each other and are electrically connected to the control unit 31. Thus, the sheath 32 is used to implement the linear displacement sensor. Because the sheath 32 is fixed to the nut 24, the linear displacement sensor can accurately read the displacement data of the nut 24.

[0059] Furthermore, the rotary encoder is preferably configured as follows: the rotary encoder includes a second reading unit 35 and a magnetic pole 36. A magnet sheath 37 is fixedly mounted on one end of the lead screw 25. The magnetic pole 36 is fixedly mounted on the magnet sheath 37. The magnetic pole 36 is positioned opposite the second reading unit 35. The second reading unit 35 is electrically connected to the control unit 31. Thus, the magnetic pole 36 is directly fixed to the end of the lead screw 25, allowing accurate reading of the rotation data of the lead screw 25.

[0060] In summary, the actuator 2 used in this embodiment, by using a planetary roller screw pair, effectively reduces the lead, improves the load-bearing capacity, and makes the internal transmission structure more compact and the energy density improved; and adopts a design of direct connection between the motor and the screw 25, which effectively improves the integration of the structural layout and reduces the cost.

[0061] Combining Examples 1 and 2, we can see that the multi-link design of the finger joint assembly in this embodiment, a one-degree-of-freedom finger structure, ensures good rigidity and stability while maintaining high flexibility. Furthermore, the finger joint assembly, combined with actuator 2, forms a direct-drive design, ensuring strong load-bearing capacity. When applied to a robotic arm, it can provide strong grasping flexibility and stability.

[0062] The above schematically describes the present invention and its embodiments, which are not restrictive. The accompanying drawings only illustrate one embodiment of the present invention, and the actual structure is not limited thereto. Therefore, if a person skilled in the art is inspired by the above and, without departing from the inventive purpose of the present invention, designs structures and embodiments similar to the technical solution without creatively designing them, they shall fall within the scope of protection of the present invention.

Claims

1. A 1-DOF finger structure, characterized in that: It includes an actuator (2) and a finger joint assembly (1); The actuator (2) includes an output end (21) that moves in a straight line, a connecting tool (22) is fixedly provided at the end of the actuator (2), and the output end (21) passes through the connecting tool (22); a first connecting portion (23) is fixedly provided on the connecting tool (22), and the first connecting portion (23) is located on one side of the output end (21); The finger joint assembly (1) comprises a first connecting rod (11), a second connecting rod (12), a fingertip seat (13), a transmission connecting rod (14), a first coupling connecting rod (15) and a second coupling connecting rod (16); a second connecting portion (131) is fixedly provided on the fingertip seat (13); The first connecting rod (11) is hinged to the first connecting portion (23) to form a first rotation pair R1, the second connecting rod (12) is hinged to the first connecting rod (11) to form a second rotation pair R2, and the second connecting rod (12) is hinged to the second connecting portion (131) to form a third rotation pair R3. When the finger joint assembly (1) is fully extended, the rotation center lines of the first rotation pair R1, the second rotation pair R2 and the third rotation pair R3 are parallel and coplanar. A first extension portion (111) is provided on one side of the first connecting rod (11) facing the output end (21), and both ends of the transmission connecting rod (14) are hinged to the output end (21) and the first extension portion (111), respectively; A second extension portion (231) is fixedly provided on the first connecting portion (23) on a side facing the output end (21); a third extension portion (121) is fixedly provided on the second connecting rod (12) at a position close to the second rotation pair R2; the third extension portion (121) is located on a side of the second connecting rod (12) facing away from the output end (21); and two ends of the first coupling connecting rod (15) are hinged to the second extension portion (231) and the third extension portion (121), respectively; A fourth extension portion (112) is fixedly provided on the first connecting rod (11) at a position close to the second rotation pair R2, and the fourth extension portion (112) is located on the side of the first connecting rod (11) facing the output end (21); a fifth extension portion (132) is fixedly provided on the fingertip seat (13), and the fifth extension portion (132) is located on the side of the second connecting portion (131) away from the output end (21); and both ends of the second coupling connecting rod (16) are hinged to the fourth extension portion (112) and the fifth extension portion (132) respectively.

2. The one-degree-of-freedom finger structure according to claim 1, characterized in that: The transmission connecting rod (14) is in an arc shape, and the concave side of the arc-shaped transmission connecting rod (14) faces the first connecting rod (11).

3. A one-degree-of-freedom finger structure according to claim 1 or 2, characterized in that: There is a bend on the first coupling link (15) at a position close to the first rotation pair R1 and the second rotation pair R2, and there is a bend on the second coupling link (16) at a position close to the second rotation pair R2 and the third rotation pair R3.

4. The one-degree-of-freedom finger structure according to claim 1, characterized in that: A contoured cover (17) is fixedly provided on the outer sides of the first connecting rod (11), the second connecting rod (12) and the fingertip seat (13).

5. The one-degree-of-freedom finger structure according to claim 1, characterized in that: The length of the first connecting rod (11) is greater than the length of the second connecting rod (12), and the length of the second connecting rod (12) is greater than the length of the fingertip seat (13).

6. The one-degree-of-freedom finger structure according to claim 1, characterized in that: The actuator (2) comprises a housing (20), wherein a planetary roller screw pair and a motor are arranged in the housing (20); The planetary roller screw pair comprises a nut (24), a screw (25), a roller (26) and a retaining frame (27); the nut (24) is arranged on the outside of the screw (25); a plurality of rollers (26) are arranged around the screw (25) and the nut (24); the rollers (26) are respectively engaged with the nut (24) and the screw (25); the output end (21) is fixedly connected to the nut (24); the retaining frame (27) is located between the nut (24) and the screw (25); and both ends of the rollers (26) are respectively rotatably connected to the retaining frame (27); The motor comprises a stator (28) and a rotor (29), wherein the stator (28) is arranged outside the rotor (29) and fixedly connected to the housing (20), and the lead screw (25) is fixedly connected to the rotor (29); A spherical bearing (30) is provided at one end of the actuator (2), a tension and pressure sensor is provided at one end of the housing (20) close to the spherical bearing (30), a rotary encoder is provided between the lead screw (25) and the housing (20), a linear displacement sensor is provided between the output end (21) and the inner wall of the housing (20), a control unit (31) is provided in the housing (20), and the motor, the linear displacement sensor, the rotary encoder and the tension and pressure sensor are all electrically connected to the control unit (31).

7. The one-degree-of-freedom finger structure according to claim 6, characterized in that: The roller (26) includes a first meshing section (261) and a second meshing section (262), wherein the median diameter of the first meshing section (261) is larger than the median diameter of the second meshing section (262), the first meshing section (261) meshes with the external thread of a portion of the lead screw (25), and the second meshing section (262) meshes with the internal thread of the nut (24); The number of thread heads of the lead screw (25) and the nut (24) is the same, the thread profiles of the lead screw (25) and the nut (24) are both triangular, the lead of the threads on the first meshing section (261) and the second meshing section (262) is zero, and the thread profiles on the first meshing section (261) and the second meshing section (262) are semicircular.

8. The one-degree-of-freedom finger structure according to claim 6, characterized in that: A sheath (32) is fixedly provided on the outer side of the nut (24), and the sheath (32) is used to abut against the inner wall of the housing (20).

9. The one-degree-of-freedom finger structure according to claim 6, characterized in that: The linear displacement sensor comprises a first reading unit (33) and a magnetic grid (34), wherein the magnetic grid (34) is fixedly arranged on the outside of the nut (24), and the first reading unit (33) is fixedly arranged on the inside of the housing (20), the first reading unit (33) and the magnetic grid (34) are arranged opposite to each other, and the first reading unit (33) is electrically connected to the control unit (31).

10. The one-degree-of-freedom finger structure according to claim 6, characterized in that: The rotary encoder includes a second reading unit (35) and a magnetic pole (36), one end of the lead screw (25) is fixedly provided with a magnet sheath (37), the magnetic pole (36) is fixedly provided on the magnet sheath (37), the magnetic pole (36) and the second reading unit (35) are arranged opposite to each other, and the second reading unit (35) is electrically connected to the control unit (31).

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