A large opening and closing range mechanical gripper based on under-actuation principle

Abstract

The present application belongs to the technical field of mechanical gripper, and particularly relates to a large opening and closing range mechanical gripper based on the under-actuation principle, which is used to solve the problem of complex control of the multi-degree-of-freedom mechanical gripper due to too many driving sources. The mechanical gripper comprises a rack, a driving unit, a symmetrical motion unit and two finger units arranged on the rack. The finger unit comprises a first motion joint, a root knuckle, a second motion joint and a terminal knuckle connected in sequence. An elastic member for elastically pulling the two root knuckles is arranged between the two root knuckles. A connecting rod is connected between the first motion joint and the second motion joint. The driving unit is connected to the two first motion joints and is used to drive the two first motion joints to move synchronously so as to open and close the two root knuckles. The symmetrical motion unit is used to constrain the two root knuckles to move synchronously and symmetrically on the rack. The mechanical gripper is convenient to control, and a single driving unit is used to drive multiple finger units to realize the effect of multi-degree-of-freedom large opening and closing range clamping action.

Description

Technical Field

[0001] This invention relates to the field of mechanical gripper technology, and more specifically, to a mechanical gripper with a large opening and closing range based on the underactuated principle. Background Technology

[0002] A robotic gripper is a mechanical device used to grasp, hold, or manipulate objects. As an end effector in robots, robotic grippers play a vital role in enhancing robot capabilities, adapting to different task scenarios, and improving the success rate and reliability of tasks.

[0003] In the research and application of multi-fingered robotic grippers, the fingers of the gripper are generally constructed by connecting several joints in series. However, in order to enhance the anthropomorphism and flexibility of the gripper, it is often necessary to design more joint degrees of freedom for the gripper's fingers, and then configure a drive source and sensor for each degree of freedom. Such a design can easily lead to too many drive sources, complex control, and reduced flexibility and controllability of the gripper, which urgently needs to be improved. Summary of the Invention

[0004] To improve the problem of complex control of multi-degree-of-freedom mechanical grippers due to too many drive sources, this invention provides a mechanical gripper with a large opening and closing range based on the underactuated principle.

[0005] This invention provides a large opening and closing range mechanical gripper based on the underactuated principle, employing the following technical solution:

[0006] A large-range mechanical gripper based on the underactuated principle includes a frame. The frame is equipped with: two sets of finger units symmetrically arranged on the frame; each finger unit includes a first kinematic joint, a root phalanx, a second kinematic joint, and a distal phalanx connected sequentially; the middle portion of the root phalanx is rotatably connected to the frame; a drive unit connected to the two first kinematic joints, used to drive the two first kinematic joints to move synchronously, thereby causing the two root phalanxes to open and close relative to each other; and a symmetrical kinematic unit used to constrain the two root phalanxes, enabling them to move synchronously and symmetrically on the frame; a connecting rod movably connecting the first and second kinematic joints, the moving first kinematic joint driving the second kinematic joint to move via the connecting rod, causing the two distal phalanxes to open and close relative to each other.

[0007] By adopting the above technical solution, during use, the drive unit, the first motion joint, and the root phalanx form a single motion chain; the drive unit, the first motion joint, the root phalanx, the connecting rod, the second motion joint, and the distal phalanx form another motion chain, and multiple motion chains are driven by a single drive unit. The finger unit under this configuration has more degrees of freedom, and a single drive unit is easier to control, making the mechanical gripper have multiple advantages such as simple control, high flexibility, and strong controllability.

[0008] During use, under the constraint of the symmetrical motion unit, the root phalanges of the two finger units are driven by a single drive unit to perform opening and closing movements; while the terminal phalanges at the ends of the two root phalanges can also perform opening and closing movements under the drive of the second motion joint, thus giving the mechanical gripper a large opening and closing range, and giving the mechanical gripper the characteristics of large gripping range, high degree of freedom, high stability and few drive sources.

[0009] As a further preferred embodiment, the first moving joint includes a triangular connecting plate, a transmission structure, and a connecting structure. One corner of the triangular connecting plate is rotatably connected to the frame, one corner is away from the frame and connected to the drive unit through the transmission structure, and one corner is movably connected to the root phalanx through the connecting structure.

[0010] By adopting the above technical solution, the triangular connecting plate is set as the core module of the joint, so that the drive unit can drive the root phalanx through the transmission structure and the triangular connecting plate. It also facilitates the drive unit to drive the second unit through the triangular connecting plate and the connecting rod, thereby realizing the movement of the end phalanx and realizing the multi-degree-of-freedom adjustment of the finger unit.

[0011] As a further preferred embodiment, the connecting structure includes a movable pin fixed to one corner of the triangular connecting plate, a strip-shaped hole is provided on the surface of the root phalanx, the extension direction of the strip-shaped hole is consistent with the swing direction of the root phalanx, the movable pin passes through the strip-shaped hole, and the movable pin can be separated and touch the two side walls of the strip-shaped hole under the drive of the triangular connecting plate.

[0012] By adopting the above technical solution, the movable pin and strip hole realize the delayed hysteresis adjustment between the end phalanx and the root phalanx, so that the adjustment between the end phalanx and the root phalanx can achieve flexible sequential action, and the mechanical gripper can flexibly perform multi-gradient adjustment to achieve a wide range of clamping action.

[0013] As a further preferred embodiment, the second motion joint includes a connecting rod and an adjusting rod, the connecting rod and the adjusting rod being arranged crosswise, one end of the connecting rod being rotatably connected to the outer side of the end of the root phalanx, and the opposite end being rotatably connected to the inner side of the end phalanx; the middle part of the adjusting rod is rotatably connected to the inner side of the end of the root phalanx, one end of its length direction is rotatably connected to the end of the connecting rod away from the first joint, and the other end is bent and rotatably connected to the outer side of the end phalanx.

[0014] By adopting the above technical solution, the connecting rod and adjusting rod are combined into a reverse cross linkage mechanism, so that when the drive unit is used to drive the first motion joint to move so as to open the two phalanges, the two first motion joints drive the two end phalanges to open each other through the connecting rod, connecting rod and adjusting rod, so as to realize the large-range opening and closing of the mechanical claw.

[0015] As a further preferred embodiment, the symmetrical motion unit includes a central rod and two pull rods. The middle part of the central rod is rotatably connected to the frame. The two pull rods are symmetrically arranged with the rotatable connection between the central rod and the frame as the center. One end of each pull rod is rotatably connected to both ends of the central rod, and the opposite ends of each pull rod are rotatably connected to the root of each of the two root phalanges.

[0016] By adopting the above technical solution, the two phalanges form motion constraints through the pull rod and the central rod. Thus, during the process of the drive unit driving the two first motion joints, under the combined constraints of the two pull rods and the central rod, the two phalanges can only perform opening and closing movements synchronously, ensuring the stability of the mechanical gripper's gripping of objects and the uniformity of the phalange's movements.

[0017] As a further preferred embodiment, the drive unit includes a telescopic power component, the fixed end of which is connected to a transmission structure, and the telescopic end of which is connected to another transmission structure.

[0018] By adopting the above technical solution, during use, the telescopic power component performs telescopic movement, realizing the adjustment of the distance between the telescopic power component and the two transmission structures. Thus, under the constraint of the symmetrical motion unit, the opening and closing movement between the two finger joints is realized, achieving the under-drive operation effect of the mechanical claw.

[0019] As a further preferred embodiment, the transmission structure includes a triangular transmission plate and a transmission rod. One corner of the triangular transmission plate is rotatably connected to the frame, one corner is movably connected to the telescopic power component, and one corner is rotatably connected to the connecting rod. The triangular transmission plate, the transmission rod, the triangular connecting plate, and the frame form a parallelogram mechanism.

[0020] By adopting the above technical solution, a parallelogram mechanism is formed between the triangular transmission plate, transmission rod, triangular connecting plate and frame, which enables the drive unit to stably transmit highly accurate motion through the parallelogram mechanism, ensuring the high stability and high precision of the mechanical gripper.

[0021] As a further preferred embodiment, a clamping block is fixedly provided on the inner side of the middle part of the root phalanx, and the two clamping blocks and the two terminal phalanxes form an article clamping area.

[0022] By adopting the above technical solution, the object held on the mechanical gripper is limited by multiple points and a large area of ​​the gripping block and the end phalanx, so as to greatly improve the gripping stability of the object on the mechanical gripper.

[0023] As a further preferred embodiment, an elastic element is provided between the roots of the two root phalanges to elastically tighten them together.

[0024] By adopting the above technical solution, the two root knuckles are tightened by the elastic force of the elastic element, so that the root knuckles can still maintain a stable initial state when not driven by the driving unit.

[0025] As a further preferred embodiment, the frame includes two spaced-apart base plates, with an assembly cavity formed between the two base plates for assembling symmetrical motion units and root phalanges.

[0026] By adopting the above technical solution, the two substrates can provide external protection for the symmetrical motion unit and the root phalanx, thus protecting the symmetrical motion unit and the root phalanx.

[0027] In summary, the present invention has at least the following beneficial technical effects:

[0028] 1. Under the constraint of the symmetrical motion unit, the root phalanges of the two finger units are driven by a single drive unit to perform opening and closing movements; at the same time, the terminal phalanges at the ends of the two root phalanges can also perform opening and closing movements under the drive of the second motion joint, so that the mechanical gripper has a large opening and closing range, and the mechanical gripper has the characteristics of large gripping range, high degree of freedom, high stability and few drive sources.

[0029] 2. The drive unit, the first motion joint, and the root phalanx form a motion chain, and the drive unit, the first motion joint, the root phalanx, the connecting rod, the second motion joint, and the distal phalanx form another motion chain. All of these motion chains are driven by a single drive unit. The finger unit in this configuration can achieve multi-degree-of-freedom adjustment with only a single drive unit, giving the mechanical gripper multiple advantages such as ease of control, high flexibility, and strong controllability.

[0030] 3. The movable pin and strip hole enable the adjustment of the delay hysteresis between the end phalanx and the root phalanx, allowing the end phalanx and the root phalanx to move in sequence flexibly, enabling the mechanical gripper to perform a wide range of gripping actions.

[0031] 4. Each finger unit, drive unit, and symmetrical motion unit is highly integrated and flattened on the substrate, enabling the mechanical gripper to perform multi-degree-of-freedom gripping operations with a large opening and closing range in various narrow spaces and gaps under program control, with a small size structure. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present invention;

[0033] Figure 2 This is a structural schematic diagram of the symmetrical motion unit inside the display frame;

[0034] Figure 3 It is a display Figure 2 Enlarged view of point A in the middle.

[0035] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0036] 1. Frame; 11. Base plate; 2. Drive unit; 21. Telescopic power component; 3. Symmetrical motion unit; 31. Center rod; 32. Pull rod; 4. First motion joint; 41. Triangular connecting plate; 42. Triangular transmission plate; 43. Transmission rod; 44. Movable pin; 5. Root finger joint; 51. Elastic component; 52. Mounting ring; 53. Strip hole; 54. Clamping block; 6. Second motion joint; 61. Connecting rod; 62. Adjusting rod; 7. End finger joint; 8. Connecting rod; 9. Y-shaped plate. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0038] In the description of this invention, it should be understood that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0039] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0040] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0041] The following is in conjunction with the appendix Figure 1-3The present invention will be described in further detail below.

[0042] This invention discloses a mechanical gripper with a large opening and closing range based on the underactuated principle.

[0043] Reference Figure 1 and Figure 2 A large-range mechanical gripper based on the underactuated principle includes a frame 1, on which finger units, a drive unit 2, and a symmetrical motion unit 3 are mounted. Two sets of finger units are symmetrically arranged on the frame 1. Each finger unit includes a first motion joint 4, a root phalanx 5, a second motion joint 6, and a distal phalanx 7 connected sequentially. An elastic element 51 is provided between the roots of the two root phalanxes 5 to elastically tighten them. The first motion joint 4 and the root phalanx 5 form a first motion chain. A connecting rod 8 is provided on the outer side of each root phalanx 5, positioned between the first motion joint 4 and the second motion joint 6. The first motion joint 4 can drive the second motion joint 6 to move via the connecting rod 8, causing the two distal phalanxes 7 to open and close relative to each other. This forms a second motion chain consisting of the first motion joint 4, the root phalanx 5, the connecting rod 8, the second motion joint 6, and the distal phalanx 7. The drive unit 2 connects to the two first motion joints 4 and drives them to move synchronously, thereby causing the two root phalanxes 5 to open and close. The symmetrical motion unit 3 is located between the two root phalanges 5 to constrain the two root phalanges 5, so that the two root phalanges 5 move synchronously and symmetrically on the frame 1.

[0044] Furthermore, refer to Figure 1 and Figure 2 The frame 1 includes two spaced-apart base plates 11, with an assembly cavity formed between the two base plates 11 for assembling the symmetrical motion unit 3 and the root finger joints 5. The side of the two root finger joints 5 that is close to each other is the inner side, and the side that is away from each other is the outer side. The inner side of each root finger joint 5 is fixed with a mounting ring 52.

[0045] In this embodiment, the elastic element 51 includes a spring, with both ends of the spring fixed to the two mounting rings 52, and the spring is tensioned between the two root joints 5. In other embodiments, the elastic element 51 can also be an elastic structure such as a spring sheet, an elastic pad, or an elastic rope, as long as it can elastically tighten the roots of the two root joints 5.

[0046] Furthermore, the drive unit 2 includes a telescopic power component 21, which is disposed on the side of the frame 1 and faces the opening direction of the mechanical claw to avoid collision interference with the grasped target.

[0047] Furthermore, refer to Figure 1 and Figure 2The first moving joint 4 includes a triangular connecting plate 41, a transmission structure, and a connecting structure. One corner of the triangular connecting plate 41 is rotatably connected to the frame 1 and the root finger joint 5 via a pin; another corner is away from the frame 1 and connected to the drive unit 2 via the transmission structure; and the third corner is movably connected to the root finger joint 5 via the connecting structure. This allows the drive unit 2 to drive the triangular connecting plate 41 to move via the transmission structure, thereby driving the root finger joint 5 through the moving triangular connecting plate 41.

[0048] Furthermore, two transmission structures are symmetrically arranged on opposite sides of the frame 1. The transmission structure includes a triangular transmission plate 42 and a transmission rod 43, with the triangular transmission plate 42 and transmission rod 43 close to the telescopic power member 21. One corner of the triangular transmission plate 42 is rotatably connected to the frame 1 via a pin, another corner is movably connected to the telescopic power member 21 via a pin, and another corner is rotatably connected to the end of the transmission rod 43 via a pin. The end of the transmission rod 43 away from the triangular transmission plate 42 is rotatably connected to one corner of the triangular connecting plate 41. The triangular transmission plate 42, transmission rod 43, triangular connecting plate 41, and frame 1 form a parallelogram mechanism.

[0049] It should be noted that the rotation axis of each pin is aligned with the thickness direction of the base plate 11. In this embodiment, the telescopic power component 21 is a cylinder, which is connected to the air circuit and is controlled by a program. In other embodiments, the telescopic power component 21 can also be a hydraulic cylinder, an electric push rod, etc., as long as it can achieve the rotational adjustment of the two triangular transmission plates 42. The transmission rod 43 can also be replaced with a flexible traction rope, a high-toughness metal wire, etc.

[0050] In some feasible embodiments, the transmission structure may further include a roller and a pull rope. The roller is rotatably mounted on the frame 1, and its rotation axis coincides with the rotation axis of the root finger 5. The pull rope is located on one side of the frame 1 and wrapped around the surface of the roller. One end of the pull rope is connected to the end of the telescopic power member 21, and the other end is connected to the triangular connecting plate 41. By pulling or releasing the pull rope through the telescopic power member 21, the pull rope drives the triangular connecting plate 41 to move, thereby realizing motion transmission.

[0051] Furthermore, refer to Figure 2 and Figure 3 In this embodiment, the connecting structure includes a movable pin 44, which is fixed to one corner of the triangular connecting plate 41. A strip-shaped hole 53 is formed on the surface of the root phalanx 5, the extension direction of which is consistent with the swing direction of the root phalanx 5. One end of the movable pin 44 passes through the strip-shaped hole 53. During the operation of the mechanical gripper, the movable pin 44, driven by the triangular connecting plate 41, can detachably contact the two side walls of the strip-shaped hole 53 along its extension direction, thereby driving the root phalanx 5 to move.

[0052] In other embodiments, the movable pin 44 may be disposed on the surface of the root phalanx 5; and the strip hole 53 is correspondingly disposed on the surface of the triangular connecting plate 41 and is adapted to the movable pin 44.

[0053] Furthermore, refer to Figure 2 To achieve synchronous and symmetrical movement of the two root phalanges 5, the symmetrical movement unit 3 includes a central rod 31 and two pull rods 32. The central rod 31 is located between the two root phalanges 5, and its middle part is rotatably connected to the frame 1 via a pin. The two pull rods 32 are symmetrically arranged around the rotatable connection point between the central rod 31 and the frame 1. One end of each pull rod 32 is rotatably connected to both ends of the central rod 31, and the opposite ends of each pull rod 32 are rotatably connected to the roots of the two root phalanges 5. In other embodiments, the central rod 31 can also be replaced by a disc, a gear disc, or other structures.

[0054] By using two sets of anti-symmetrically arranged tie rods 32 on the symmetrical motion unit 3, the motion constraint of the root phalanx 5 is achieved, thereby ultimately realizing the symmetrical movement of the two sets of finger units under the condition of a single drive unit 2.

[0055] Furthermore, the second motion joint 6 includes a connecting rod 61 and an adjusting rod 62. The connecting rod 61 and the adjusting rod 62 are arranged crosswise. One end of the connecting rod 61 is rotatably connected to the outer side of the end of the root phalanx 5 via a pin, and the opposite end is rotatably connected to the inner side of the distal phalanx 7 via a pin. The middle part of the adjusting rod 62 is rotatably connected to the inner side of the end of the root phalanx 5 via a pin, one end of its length is rotatably connected to the end of the connecting rod 8 away from the first joint via a pin, and the other end is bent and rotatably connected to the outer side of the distal phalanx 7 via a pin.

[0056] The connecting rod 61, the root phalanx 5, and the adjusting rod 62 are combined to form a reverse cross linkage mechanism, so that when the drive unit 2 drives the first motion joint 4 to move and open the two root phalanxes 5, the two first motion joints 4 also drive the two end phalanxes 7 to open with each other through the connecting rod 8, the connecting rod 61, and the adjusting rod 62; at the same time, the motion joints and the base plate are highly integrated and flattened, so that the mechanical gripper can achieve a wide range and multiple degrees of freedom of opening and closing clamping operations with a small size structure.

[0057] Furthermore, refer to Figure 1 and Figure 2 To improve the gripping stability of the mechanical claw, a gripping block 54 is fixedly provided on the inner side of the middle part of the root phalanx 5. A Y-shaped plate 9 is fixed on the outer surface of the side of one base plate 11 away from the other base plate 11. The Y-shaped plate 9 is misaligned with the finger unit. The two supports of the Y-shaped plate 9 extend toward the two end phalanxes 7 and form an arc-shaped limiting profile on one side of the two root phalanxes 5. The two gripping blocks 54, the two end phalanxes 7, and the Y-shaped plate 9 form an object gripping area.

[0058] Furthermore, the Y-shaped plate 9 is fixed to the base plate 11 by multiple bolts, and the multiple bolts are arranged along the direction of the end finger 7 of the base plate 11. During use, the position of the Y-shaped plate 9 on the base plate 11 can be adjusted along the direction close to the end finger 7 by adjusting the number of bolts and the installation position of the Y-shaped plate 9 on the base plate 11, so as to adjust the final bolt locking position of the Y-shaped plate 9 on the base plate 11.

[0059] During use, the telescopic power component 21 is controlled by a program. When the two sets of root phalanges 5 are stretched by springs to reach their mechanical limit positions, they remain stationary relative to the frame 1. The telescopic power component 21 drives the triangular transmission plate 42. Since the triangular transmission plate 42, transmission rod 43, triangular connecting plate 41, and frame 1 form a parallelogram mechanism, the parallelogram mechanism drives the end phalanges 7 through the connecting rod 8 and the second motion joint 6. When the movable pin 44 at one corner of the triangular connecting plate 41 moves to the inner wall of the extension direction of the strip hole 53, the movable pin 44 drives the root phalanges 5 to move. At this time, the relative positions of the root phalanges 5, the second motion joint 6, and the end phalanges 7 remain stationary. The three as a whole achieve a large opening and closing action under the drive of the parallelogram mechanism.

[0060] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A mechanical gripper with a large opening and closing range based on the underactuated principle, characterized in that, Includes a frame (1), said frame (1) being provided with: Two sets of finger units are symmetrically arranged on the frame (1). Each finger unit includes a first kinematic joint (4), a root knuckle (5), a second kinematic joint (6), and a distal knuckle (7) that are connected in sequence. The drive unit (2) is connected to the two first motion joints (4) and is used to drive the two first motion joints (4) to move synchronously so as to drive the two root phalanges (5) to open and close to each other. Symmetrical motion unit (3) is used to constrain the two root phalanges (5) so that the two root phalanges (5) move synchronously and symmetrically on the frame (1); A connecting rod (8) is provided between the first motion joint (4) and the second motion joint (6) to connect them. The first motion joint (4), driven by the driving unit (2), drives the second motion joint (6) through the connecting rod (8), so that the two end phalanges (7) open and close to each other. The first moving joint (4) includes a triangular connecting plate (41), a transmission structure and a connecting structure. One corner of the triangular connecting plate (41) is rotatably connected to the frame (1), one corner is away from the frame (1) and connected to the drive unit (2) through the transmission structure, and one corner is movably connected to the root finger joint (5) through the connecting structure. The connecting structure includes a movable pin (44) fixed to one corner of the triangular connecting plate (41), and a strip hole (53) is provided on the surface of the root phalanx (5). The extension direction of the strip hole (53) is consistent with the swing direction of the root phalanx (5). The movable pin (44) passes through the strip hole (53). Under the drive of the triangular connecting plate (41), the movable pin (44) can detachably touch the two inner sidewalls of the extension direction of the strip hole (53). The drive unit (2) includes a telescopic power component (21), the fixed end of which is connected to a transmission structure, and the telescopic end of which is connected to another transmission structure. The second motion joint (6) includes a cross-connecting rod (61) and an adjusting rod (62). One end of the connecting rod (61) is rotatably connected to the outer side of the end of the root phalanx (5), and the opposite end is rotatably connected to the inner side of the end phalanx (7). The middle part of the adjusting rod (62) is rotatably connected to the inner side of the end of the root phalanx (5), and one end of its length direction is rotatably connected to the end of the connecting rod (8) away from the first motion joint (4), while the other end is bent and rotatably connected to the outer side of the end phalanx (7). The symmetrical motion unit (3) includes a central rod (31) and two pull rods (32). The middle part of the central rod (31) is rotatably connected to the frame (1). The two pull rods (32) are symmetrically arranged with the rotatable connection between the central rod (31) and the frame (1) as the center. One end of the two pull rods (32) is rotatably connected to both ends of the central rod (31). The opposite ends of the two pull rods (32) are rotatably connected to the roots of the two root phalanges (5).

2. The large opening and closing range mechanical gripper based on the underactuated principle according to claim 1, characterized in that, The transmission structure includes a triangular transmission plate (42) and a transmission rod (43). One corner of the triangular transmission plate (42) is rotatably connected to the frame (1), one corner is movably connected to the telescopic power component (21), and one corner is rotatably connected to the transmission rod (43). The end of the transmission rod (43) away from the triangular transmission plate (42) is rotatably connected to the triangular connecting plate (41) and the connecting rod (8). The triangular transmission plate (42), the transmission rod (43), the triangular connecting plate (41), and the frame (1) form a parallelogram mechanism.

3. A large-range opening and closing mechanical gripper based on the underactuated principle according to claim 1, characterized in that, A clamping block (54) is fixedly provided on the inner side of the middle part of the root phalanx (5), and the two clamping blocks (54) and the two terminal phalanxes (7) form an article clamping area.

4. A large-range opening and closing mechanical gripper based on the underactuated principle according to claim 1, characterized in that, An elastic element (51) is provided between the roots of the two root phalanges (5) to elastically tighten them together.

5. A large-range opening and closing mechanical gripper based on the underactuated principle according to claim 1, characterized in that, The frame (1) includes two spaced-apart base plates (11), and an assembly cavity for assembling the symmetrical motion unit (3) and the root phalanx (5) is formed between the two base plates (11).

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