A robot end effector suitable for fish body gripping on a production line

Abstract

The application discloses a robot end effector suitable for fish body grabbing in a production line. The end effector comprises a driving mechanism, a bent link structure, a main base and an asymmetric four-finger structure. The driving mechanism is installed at the center of the main base, the bent link structure is hinged on the driving mechanism and the main base, and the root end of the asymmetric four-finger structure is installed on the bottom surface of the bent link structure. The end of the asymmetric four-finger structure faces the production line. The driving mechanism drives the bent link structure, and then drives the asymmetric four-finger structure to move towards each other to grab the fish body. The fish body can be quickly turned from a lying state to an upright state, and then firmly grabbed to move smoothly. The end effector has controllability, and can effectively meet the stable and efficient grabbing requirements of fish bodies within a certain size range.

Description

TECHNICAL FIELD

[0001] The application relates to a robot end effector and relates to the technical field of robots, in particular to a robot end effector suitable for fish body grabbing on a production line. BACKGROUND

[0002] With the advancement of robot technology, the fish processing industry is rapidly developing towards automation and intelligence. In fish processing, fish bodies usually need to be sorted, oriented, fed, cut and packaged. These steps are gradually shifting from manual operation to robot automation to improve production efficiency and reduce labor costs. Among them, fish body grabbing is a crucial step in fish processing, that is, the robot uses a mechanical arm and an end effector to grab the flat fish on the production line for the next operation. The complex shape of the fish body, the slippery surface and the individual differences make the fish body prone to damage and falling during grabbing, which brings many challenges to the design and development of the robot end effector in fish processing.

[0003] Existing fish body grabbing devices are mostly rigid structures. Patent CN107711745A discloses a long handle fish grabbing device, which grabs fish bodies through fish grabbing claws. Patent CN212212413U discloses a new fish grabbing rod, which grabs fish bodies through fish grabbing forceps. Similar rigid end effectors are subject to fish body shape and size, and the grabbing force is difficult to control, which can easily cause fish body damage, misplacement and fish body slipping, and cannot meet the fish body grabbing requirements on the fish processing production line. The current general-purpose flexible end effector usually adopts a symmetrical design and is mostly controlled by air pressure. It is suitable for grabbing objects with rough or dry surfaces, but still has great limitations for grabbing fish bodies with slippery surfaces, especially in fish processing production, it cannot stably grab fish bodies in a flat posture on the production line. Therefore, it is urgent to develop a robot end effector for fish body grabbing on the production line to improve the intelligent level of fish processing, reduce labor costs and improve production efficiency. SUMMARY

[0004] In order to solve the problems in the background art, the application provides a robot end effector suitable for fish body grabbing on a production line, which can realize the rapid turning of fish bodies from a flat posture to an upright posture and firmly grab the fish bodies for smooth movement, has controllability, and can effectively meet the stable and efficient grabbing requirements of fish bodies within a certain size range.

[0005] The technical scheme adopted by the application is:

[0006] The robot end effector suitable for production line fish body grabbing of the application comprises a driving mechanism, a bent link structure, a main base and an asymmetric four-finger structure, the driving mechanism is installed at the center of the main base, the bent link structure is hinged on the driving mechanism and the main base, the root end of the asymmetric four-finger structure is installed on the bottom surface of the bent link structure, and the end of the asymmetric four-finger structure faces the production line.

[0007] The asymmetric four-finger structure comprises two fin strip structures I and two fin strip structures II, the root ends of the two fin strip structures I are installed on one side of the bottom surface of the bent link structure and are symmetrically arranged at intervals, the root ends of the two fin strip structures II are installed on the other side of the bottom surface of the bent link structure and are symmetrically arranged at intervals, each fin strip structure I faces a respective fin strip structure II, and the four sides of the two fin strip structures I and the two fin strip structures II facing each other serve as respective finger palm surfaces.

[0008] The fin strip structure I is an inverted isosceles triangle structure composed of a rigid top surface and two flexible inclined surfaces, the rigid top surface of the fin strip structure I serves as the root end of the fin strip structure I, and the top corner of the fin strip structure I serves as the end of the fin strip structure I; the center of the fin strip structure I is a hollow structure and is uniformly and evenly arranged with a plurality of flexible fins along the finger length direction of the fin strip structure I, each flexible fin is perpendicular to the finger length direction of the fin strip structure I; and symmetrically two sides of the end of the fin strip structure I are further provided with parallel arranged end shovels, the two end shovels are located on the symmetrically two sides of the finger palm surface of the fin strip structure I and are perpendicular to the finger palm surface.

[0009] The end of the fin strip structure I is located between the two end shovels and does not exceed the bottom edge of the two end shovels, the bottom edge of the end shovels near the side of the finger back surface of the fin strip structure I is higher than the side near the finger palm surface of the fin strip structure I, the end shovels are curved towards the inner side of the asymmetric four-finger structure center, the inner side of the end shovels forms an acute angle with the bottom edge of the end shovels, and the upper end of the inner side of the end shovels does not exceed the finger palm surface of the fin strip structure I.

[0010] The fin strip structure II is an inverted isosceles triangle structure with the finger back surface and the finger palm surface of the two sides of the top corner curved towards the center of the asymmetric four-finger structure, the fin strip structure II is composed of a rigid top surface and two flexible inclined surfaces with curvature, the rigid top surface of the fin strip structure II serves as the root end of the fin strip structure II, and the top corner of the fin strip structure II serves as the end of the fin strip structure II; the center of the fin strip structure II is a hollow structure and is uniformly and evenly arranged with a plurality of flexible fins along the finger length direction of the fin strip structure II, each flexible fin is perpendicular to the finger length direction of the fin strip structure II in which the flexible fin is located; and the finger palm surface of the fin strip structure II is covered with a granular rubber friction pad as a contact surface for contacting the fish body on the production line.

[0011] The fin strip structure I and the fin strip structure II are both hard TPU materials; the granular rubber friction pad is made of natural rubber material, and a plurality of cylindrical protrusions are arranged on the contact surface of the granular rubber friction pad facing the center of the asymmetric four-finger structure.

[0012] The main base is a horizontally arranged I-shaped plate structure, a through rectangular through slot is formed in the center of the main base, and the driving mechanism is installed between the rectangular through slots of the main base; the driving mechanism comprises a lead screw stepping motor, a motor base, a lead screw nut, a nut base and a driving base arranged in sequence from top to bottom, the lead screw stepping motor is installed on the top surface of the horizontally arranged motor base, the bottom surface of the motor base is installed on the top surface of the main base through a plurality of round nuts I, the center of the motor base is provided with a circular through hole, and the output shaft of the lead screw stepping motor vertically penetrates the circular through hole of the motor base; the center of the horizontally arranged nut base is provided with a stepped circular through hole, the upper hole diameter of the stepped circular through hole is larger than the lower hole diameter, the lead screw nut is installed in the upper through hole of the stepped circular through hole, and the lead screw nut is threadedly sleeved on the output shaft of the lead screw stepping motor; the bottom surface of the nut base is connected to the top surface of the horizontally arranged driving base through a plurality of round nuts II; the bending link structure is hinged on the main base and the driving base.

[0013] The bending link structure comprises four link groups, each link group comprises a U-shaped bending link I, a U-shaped bending link II and a U-shaped bending fixing piece, one end of the U-shaped bending link I is hinged to one end of the U-shaped bending link II, and the U-shaped bending fixing piece is installed on the bottom surface of the U-shaped bending link II. The other end of the U-shaped bending link I of the four link groups is hinged at four top corners of the main base respectively, the other end of the U-shaped bending link II of the four link groups is hinged at four top corners of the driving base respectively; the root ends of the two fin strip structures I and the two fin strip structures II are installed on the bottom surface of the U-shaped bending link II through the respective U-shaped bending fixing pieces.

[0014] The beneficial effects of the present application are:

[0015] 1) The robot end effector suitable for fish body grabbing of the present application has simple structure, lightweight design and low production cost; 2) The present application uses a lead screw stepping motor as a driving source, and the control mode is simple, which is convenient for device design and control; 3) The present application adopts a fin strip structure, which has the characteristics of self-adaptive fitting to objects, can improve the adaptability of the mechanical hand to the fish body shape, and reduce the fish body grabbing failure rate; 4) The present application adopts an asymmetric four-finger structure, which can realize the overturning of the fish body from lying to standing on the abdomen, thereby increasing the contact between the fish body and the flexible surface of the fin strip structure, and improving the stability of fish body grabbing.

[0016] In summary, the present invention drives the bent connecting rod structure through a driving mechanism, and then drives the asymmetric four-finger structure to move toward each other to grasp the fish body. It can realize the rapid flipping of the fish body from a lying flat state to an upright state on the belly and back, and then firmly grasp the fish body for smooth movement. It has a certain degree of controllability and can effectively meet the stable and efficient grasping needs of fish bodies within a certain size range. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0018] Figure 2 It is a structural diagram of the driving mechanism;

[0019] Figure 3 It is a structural diagram of the bent connecting rod structure;

[0020] Figure 4 This is a schematic diagram of the structure of the asymmetric four-finger fin structure I;

[0021] Figure 5 This is a schematic diagram of the structure of the asymmetric four-finger fin structure II;

[0022] Figure 6 It is a structural diagram of the main base;

[0023] Figure 7 This is a schematic diagram of the principle of the present invention when catching a fish;

[0024] In the figure: 1. Driving mechanism, 11. Screw stepper motor, 12. Motor base, 13. Round nut I, 14. Screw nut, 15. Nut base, 16. Round nut II, 17. Driving base, 2. Bending connecting rod structure, 21. U-shaped bending connecting rod I, 22. U-shaped bending connecting rod II, 23. U-shaped bending fixing part, 3. Main base, 4. Asymmetric four-finger structure, 41. Fin structure I, 42. End shovel, 43. Fin structure II, 44. Granular rubber friction pad. DETAILED DESCRIPTION

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] like Figure 1As shown, the present invention's robotic end effector for fish grabbing on a production line comprises a drive mechanism 1, a bending link structure 2, a main base 3, and an asymmetric four-finger structure 4. The drive mechanism 1 is mounted at the center of the main base 3, the bending link structure 2 is hingedly connected to the drive mechanism 1 and the main base 3, and the root end of the asymmetric four-finger structure 4 is mounted on the bottom surface of the bending link structure 2, with the distal end of the asymmetric four-finger structure 4 facing the production line. The drive mechanism 1, via the bending link structure 2, drives the asymmetric four-finger structure 4 in a mutually directed motion to grab fish on the production line. This allows for rapid flipping of the fish from a flat position to an upright position, thereby securely grasping the fish and allowing for smooth movement.

[0027] The asymmetric four-finger structure 4 includes two fin ray structures I41 and two fin ray structures II43. The root ends of the two fin ray structures I41 are installed on one side of the bottom surface of the bending connecting rod structure 2 and are arranged symmetrically at intervals. The root ends of the two fin ray structures II43 are installed on the other side of the bottom surface of the bending connecting rod structure 2 and are arranged symmetrically at intervals. Each fin ray structure I41 faces its own fin ray structure II43, and the four side surfaces facing the two fin ray structures I41 and the two fin ray structures II43 serve as their respective finger webs.

[0028] like Figure 4 As shown, the fin structure I41 is an inverted isosceles triangle structure consisting of a rigid top surface and two flexible inclined surfaces. The rigid top surface of the fin structure I41 serves as the root end of the fin structure I41, and the top angle of the fin structure I41 serves as the end of the fin structure I41. The center of the fin structure I41 is a hollow structure and a number of flexible fin rays are arranged in sequence and evenly spaced along the finger length direction of the fin structure I41. Each flexible fin ray is perpendicular to the finger length direction of the fin structure I41. Parallel end shovels 42 are also installed on the symmetrical sides of the end of the fin structure I41. The two end shovels 42 are located on the symmetrical sides of the finger ventral surface of the fin structure I41 and are perpendicular to the finger ventral surface.

[0029] The end of the fin structure I 41 is located between the two end shovel blades 42 and does not exceed the bottom edges of the two end shovel blades 42. The side of the bottom edge of the end shovel blade 42 close to the dorsal surface of the fin structure I 41 is higher than the side close to the ventral surface of the fin structure I 41. The inner side of the end shovel blade 42 toward the center of the asymmetric four-finger structure 4 is bent toward the center of the asymmetric four-finger structure 4. There is an acute angle between the inner side of the end shovel blade 42 and its own bottom edge. The upper end of the inner side of the end shovel blade 42 does not exceed the ventral surface of the fin structure I 41.

[0030] like Figure 4As shown, the end shovel 42 is an acrylic piece with a thickness of 3 mm, which is composed of a horizontal top surface, a J-shaped left side surface, an inwardly concave arc-shaped right side surface, and a bottom surface that is inclined to the right and forms an angle of 15 degrees with the horizontal top surface. The horizontal top surface of the end shovel 42 does not exceed the two flexible inclined surfaces of the fin strip structure I 41, and the arc-shaped right side surface of the end shovel 42 forms an acute angle with the bottom surface and intersects at the right side of the horizontal top surface. The end shovel 42 is provided with three cylindrical holes for fixed installation. This structural feature allows the fish body on the production line to slide upward along the arc-shaped right side surface of the end shovel 42 during the grabbing process, thereby achieving the effect of fish body turning over. At the same time, the bottom surface of the end shovel 42 can push away other fish bodies around the target fish body during the downward grabbing process of the end effector.

[0031] As shown in Figure 5 , the fin strip structure II 43 is an isosceles trapezoidal structure with the two sides of the top angle pointing backward and the two sides of the bottom angle pointing toward the center of the asymmetric four-finger structure 4. The fin strip structure II 43 is composed of a rigid top surface and two flexible inclined surfaces with curvature. The rigid top surface of the fin strip structure II 43 serves as the root end of the fin strip structure II 43, and the top angle of the fin strip structure II 43 serves as the end of the fin strip structure II 43. The center of the fin strip structure II 43 is a hollow structure and is uniformly spaced with several flexible fin strips along the finger length direction. Each flexible fin strip is perpendicular to the finger length direction of the segment of the fin strip structure II 43 it is located in. The palm surface of the fin strip structure II 43 is covered with a granular rubber friction pad 44 as the contact surface with the fish body on the production line.

[0032] As shown in Figure 5 , the granular rubber friction pad 44 is made of natural rubber material. The contact surface of the granular rubber friction pad 44 toward the center of the asymmetric four-finger structure 4 is arrayed with several cylindrical protrusions, which have a large static and dynamic friction coefficient and can effectively limit the movement of the fish body. The fin strip structure I 41 and the fin strip structure II 43 are made of hard TPU material, which makes the asymmetric four-finger structure 4 have a certain flexibility and rigidity, improving the grabbing ability of the end effector on the fish body.

[0033] As shown in Figure 4 and Figure 5As shown, fin strip structure I 41 and fin strip structure II 43 are both based on an inverted isosceles triangle structure with a base angle of 80 degrees and a base of 48 mm, consisting of a parallel arrangement of fin strip groups, a rigid top surface and two flexible inclined surfaces; the inner wall of the flexible inclined surface at the lower end of the fin strip structure I 41 is provided with three cylindrical holes for fixing the end shovel 42, the flexible inclined surface of the fin strip structure II 43 close to the fish body is bent 15 degrees towards the fish body at a vertical distance of 10 cm from the rigid top surface, and the flexible inclined surface of the fin strip structure II 43 away from the fish body is bent 25 degrees towards the fish body at a vertical distance of 11 cm from the rigid top surface. Due to the flexible deformation ability of the fin strip structure I 41 and the fin strip structure II 43, the asymmetric four-finger structure 4 can form the maximum envelope for the fish body in the upright state, thereby limiting the movement of the fish body in all directions and reducing the risk of fish body damage and falling.

[0034] As shown in Figure 2 and Figure 6 The main base 3 is a horizontally arranged I-shaped plate structure, a rectangular through slot is formed in the center of the main base 3, and the driving mechanism 1 is installed between the rectangular through slots of the main base 3; the driving mechanism 1 includes a lead screw stepper motor 11, a motor base 12, a lead screw nut 14, a nut base 15 and a driving base 17 arranged in sequence from top to bottom, the lead screw stepper motor 11 is installed on the top surface of the horizontally arranged motor base 12, the bottom surface of the motor base 12 is installed on the top surface of the main base 3 through a plurality of round nuts I 13, the center of the motor base 12 has a circular through hole, and the output shaft of the lead screw stepper motor 11 vertically penetrates the circular through hole of the motor base 12; the center of the horizontally arranged nut base 15 is provided with a stepped circular through hole, the upper hole diameter of the stepped circular through hole is larger than the lower hole diameter, the lead screw nut 14 is installed in the upper through hole of the stepped circular through hole, and the lead screw nut 14 is threadedly sleeved on the output shaft of the lead screw stepper motor 11; the bottom surface of the nut base 15 is connected to the top surface of the horizontally arranged driving base 17 through a plurality of round nuts II 16; the driving base 17 is a horizontally arranged I-shaped plate structure, and a through slot is formed in the center of the driving base 17; the bending link structure 2 is hinged on the main base 3 and the driving base 17.

[0035] As shown in Figure 3As shown, the bent link structure 2 includes four link groups, each of which includes a U-shaped bent link I 21, a U-shaped bent link II 22, and a U-shaped bent fixing member 23. One end of the U-shaped bent link I 21 is hinged to one end of the U-shaped bent link II 22, and the U-shaped bent fixing member 23 is mounted on the bottom surface of the U-shaped bent link II 22. The other ends of the U-shaped bent links I 21 of the four link groups are hinged to the four top corners of the main base 3, and the other ends of the U-shaped bent links II 22 of the four link groups are hinged to the four top corners of the drive base 17. The root ends of the two fin ray structures I 41 and the two fin ray structures II 43 are each mounted on the bottom surface of the U-shaped bent link II 22 via a respective U-shaped bent fixing member 23. By using U-shaped bent links instead of ordinary links, production costs are reduced to a certain extent.

[0036] like Figure 7 As shown, the control method of the robot end effector is as follows: when the fish body to be caught on the production line moves to the bottom, the robot end effector drives the screw stepper motor 11 to make the output shaft of the screw stepper motor 11 rotate in the forward direction, and then drives the nut base 15 and the drive base 17 to move downward in sequence through the screw nut 14, so that each connecting rod member of the bending connecting rod structure 2 drives the two fin ray structures I41 and the two fin ray structures II43 of the asymmetric four-fin structure 4 to open; until the ends of the two fin ray structures I41 and the two fin ray structures II43 are close to the top surface of the production line directly below and the fish body to be caught is located between the finger ventral surfaces of the two fin ray structures I41 and the two fin ray structures II43, the screw stepper motor 11 is driven to make the output shaft of the screw stepper motor 11 rotate in the reverse direction, thereby driving the two fin ray structures I41 and the two fin ray structures II43 to tighten. When the two fin ray structures I 41 and the two fin ray structures II 43 continue to move toward each other after coming into contact with the fish body, the flexible inclined surface of the fin ray structure II 43 close to the fish body is covered with a granular rubber friction pad 44, and its larger static and dynamic friction coefficients restrict the movement of the side of the fish body close to the fin ray structure II 43, while the side of the fish body close to the fin ray structure I 41 slides upward along the inner surface of the end shovel 42 and the flexible inclined surface of the fin ray structure I 41 close to the fish body until the fish body flips from a lying state to a ventral and dorsal upright state; due to the flexible deformation ability of the fin ray structure I 41 and the fin ray structure II 43, under the continued drive of the driving mechanism 1, the two fin ray structures I 41 and the two fin ray structures II 43 form a maximum envelope for the fish body in the ventral and dorsal upright state, restricting the movement of the fish body in all directions, thereby completing the task of grabbing the fish body on the production line. In summary, the asymmetric four-finger structure 4 can achieve a rapid flipping of the fish body from a lying state to an upright state with its belly and back erected, thereby firmly grasping the fish body for smooth movement.

[0037] The present invention used medium-sized scaled and unscaled crucian carp, tilapia, snakehead carp, and grass carp as experimental subjects, both fresh and thawed. The SCARA ES6-700-SR robotic arm was used to conduct gripping experiments on fish on a conveyor belt. Through repeated gripping experiments, the present invention achieved a 100% success rate for gripping flat-bodied fish such as crucian carp and tilapia, while the success rate for gripping round-bodied fish such as snakehead carp and grass carp exceeded 90%. Supplementary testing was also conducted for practical scenarios such as gripping position offset, fish with different ventral and dorsal orientations, fish stacking, and fish closely packed together. The present invention demonstrated excellent adaptability in all of these scenarios.

[0038] The present invention solves the problems of poor adaptability of existing end effectors to fish bodies on the production line and low grasping success rate. It can realize the rapid flipping of the fish body from a lying position to an upright position on its belly and back, and then firmly grasp the fish body for smooth movement. It has a certain degree of controllability and can effectively meet the stable and efficient grasping needs of fish bodies within a certain size range on the production line.

[0039] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions in the specification are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A robot end effector suitable for fish grabbing on a production line, characterized by: The invention comprises a driving mechanism (1), a bending connecting rod structure (2), a main base (3) and an asymmetric four-finger structure (4), wherein the driving mechanism (1) is installed at the center of the main base (3), the bending connecting rod structure (2) is hinged on the driving mechanism (1) and the main base (3), the root end of the asymmetric four-finger structure (4) is installed on the bottom surface of the bending connecting rod structure (2), and the end of the asymmetric four-finger structure (4) faces the production line; The asymmetric four-finger structure (4) includes two fin ray structures I (41) and two fin ray structures II (43), the root ends of the two fin ray structures I (41) are installed on one side of the bottom surface of the bending connecting rod structure (2) and are arranged symmetrically at intervals, and the root ends of the two fin ray structures II (43) are installed on the other side of the bottom surface of the bending connecting rod structure (2) and are arranged symmetrically at intervals, each fin ray structure I (41) faces a respective fin ray structure II (43), and the four side faces of the two fin ray structures I (41) and the two fin ray structures II (43) serve as their respective finger ventral surfaces; The fin structure I (41) is an inverted isosceles triangle structure consisting of a rigid top surface and two flexible inclined surfaces; parallel end shovels (42) are also installed on the symmetrical sides of the end of the fin structure I (41), and the two end shovels (42) are located on the symmetrical sides of the finger ventral surface of the fin structure I (41) and are perpendicular to the finger ventral surface; The end of the fin structure I (41) is located between the two end shovel blades (42) and does not exceed the bottom edges of the two end shovel blades (42). The side of the bottom edge of the end shovel blade (42) close to the dorsal surface of the fin structure I (41) is higher than the side close to the ventral surface of the fin structure I (41). The inner side of the end shovel blade (42) toward the center of the asymmetric four-finger structure (4) is bent toward the center of the asymmetric four-finger structure (4). The inner side of the end shovel blade (42) forms an acute angle with its own bottom edge. The upper end of the inner side of the end shovel blade (42) does not exceed the ventral surface of the fin structure I (41). The fin structure II (43) is an inverted isosceles triangle structure with the back and ventral surfaces of the two sides of a vertex bent toward the center of the asymmetric four-finger structure (4); the ventral surface of the fin structure II (43) is covered with a granular rubber friction pad (44) as a contact surface with the fish body on the production line.

2. The robot end effector suitable for fish grabbing on a production line according to claim 1, characterized in that: The rigid top surface of the fin structure I (41) serves as the root end of the fin structure I (41), and the top angle of the fin structure I (41) serves as the end of the fin structure I (41); the center of the fin structure I (41) is a hollow structure and a plurality of flexible fin rays are uniformly arranged in sequence along the length direction of the fin structure I (41), and each flexible fin ray is perpendicular to the length direction of the fin structure I (41).

3. The robot end effector suitable for fish grabbing on a production line according to claim 1, characterized in that: The fin structure II (43) is composed of a rigid top surface and two curved flexible inclined surfaces. The rigid top surface of the fin structure II (43) serves as the root end of the fin structure II (43), and the top angle of the fin structure II (43) serves as the end of the fin structure II (43). The center of the fin structure II (43) is a hollow structure and a number of flexible fin rays are arranged in sequence and evenly spaced along the length direction of the fin structure II (43). Each flexible fin ray is perpendicular to the length direction of the fin structure II (43) in which it is located.

4. The robot end effector suitable for fish grabbing on a production line according to claim 3, characterized in that: The fin structure I (41) and the fin structure II (43) are both made of hard TPU material; the granular rubber friction pad (44) is specifically made of natural rubber material, and the granular rubber friction pad (44) has a plurality of cylindrical protrusions arranged in an array on the contact surface facing the center of the asymmetric four-finger structure (4).

5. The robot end effector suitable for fish grabbing on a production line according to claim 1, characterized in that: The main base (3) is a horizontally arranged I-shaped plate structure, and a through rectangular through slot is provided in the center of the main base (3). The drive mechanism (1) is installed between the rectangular through slots of the main base (3); the drive mechanism (1) comprises a screw stepper motor (11), a motor base (12), a screw nut (14), a nut base (15) and a drive base (17) arranged in sequence from top to bottom, the screw stepper motor (11) is installed on the top surface of the horizontally arranged motor base (12), the bottom surface of the motor base (12) is installed on the top surface of the main base (3) through a plurality of round nuts I (13), and the motor base (12) is provided with a plurality of round nuts I (13). The center of the nut base (15) is provided with a circular through hole, and the output shaft of the screw stepper motor (11) vertically passes through the circular through hole of the motor base (12); the center of the horizontally arranged nut base (15) is provided with a stepped circular through hole, the upper side aperture of the stepped circular through hole is larger than the lower side aperture, the screw nut (14) is installed in the upper side through hole of the stepped circular through hole, and the screw nut (14) is threadedly sleeved on the output shaft of the screw stepper motor (11); the bottom surface of the nut base (15) is connected to the top surface of the horizontally arranged drive base (17) through a plurality of round nuts II (16); the bent connecting rod structure (2) is hinged on the main base (3) and the drive base (17).

6. The robot end effector suitable for fish grabbing on a production line according to claim 1, characterized in that: The bending link structure (2) includes four link groups, each link group includes a U-shaped bending link I (21), a U-shaped bending link II (22) and a U-shaped bending fixing piece (23), one end of the U-shaped bending link I (21) is hinged to one end of the U-shaped bending link II (22), and the U-shaped bending fixing piece (23) is installed on the bottom surface of the U-shaped bending link II (22); the other ends of the U-shaped bending links I (21) of the four link groups are respectively hinged at the four top corners of the main base (3), and the other ends of the U-shaped bending links II (22) of the four link groups are respectively hinged at the four top corners of the driving base (17); the root ends of the two fin ray structures I (41) and the two fin ray structures II (43) are each installed on the bottom surface of the U-shaped bending link II (22) through a respective U-shaped bending fixing piece (23).

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