End effector of picking robot with rotation telescoping function and execution method

Abstract

The present application belongs to the technical field of picking robots, and relates to a picking robot end effector with a rotating telescopic function and an execution method. The execution mechanism can realize angle adjustment of the clamping part in a small range at a picking site, avoiding injury to nearby unripe fruits and vegetables. After receiving a picking instruction, the second driving mechanism drives the first driving mechanism to pitch up and down and / or swing left and right; when the clamping part reaches the picking site for picking, first, the first driven wheel drives the ball screw nut to rotate (at this time, the second driven wheel is stationary) or the second driven wheel drives the spline nut to rotate (at this time, the first driven wheel is stationary), so that the screw key shaft extends in the axial direction; then, the first driven wheel drives the ball screw nut to rotate and the second driven wheel drives the spline nut to rotate, so that the screw key shaft rotates, thereby further driving the clamping part to rotate, separating the picking fruit or vegetable from the fruit stem, and completing the picking.

Description

Technical Field

[0001] This invention belongs to the field of harvesting robot technology, and relates to an end effector and execution method for a harvesting robot with rotation and telescopic functions. Background Technology

[0002] With the maturity of robotics technology, the reduction of costs, and its widespread application, robots have gradually entered the agricultural field and will promote the development of modern agriculture towards industrialized production, unmanned operation, and intelligence. Fruit and vegetable harvesting is characterized by strong seasonality, high labor intensity, and demanding environmental and operational requirements, making robotic operations urgently needed in agricultural production.

[0003] Currently, fruit and vegetable harvesting still relies heavily on manual labor, resulting in high labor costs and low harvesting efficiency. Manual harvesting is difficult on taller fruit trees and carries the risk of falls and injuries due to the complex working environment. Therefore, mechanized fruit and vegetable harvesting devices are needed to liberate labor, improve labor productivity, reduce labor costs, ensure the quality of fresh fruits and vegetables, and meet the real-time needs of crop growth. Although some simple harvesting robots have emerged in domestic and international research, most of these products are only designed for harvesting specific types of fruit, lacking versatility and functionality.

[0004] In response, an existing Chinese patent (publication number: CN102090210A, publication date: June 15, 2011) discloses an end effector and robot for a multi-fruit and vegetable harvesting robot. It uses an eccentric blade as a shearing mechanism, which, driven by a motor, drives the eccentric blade to cut, thus improving harvesting efficiency to some extent. However, because this actuator relies on the eccentric blade, it is prone to accidentally damaging nearby unripe fruits and vegetables, especially clustered fruits and vegetables such as jujubes and oranges, when the actuator's movement distance is short. It is currently unable to harvest other clustered fruits and vegetables. Therefore, there is an urgent need to design an end effector suitable for multi-type fruit and vegetable harvesting robots that can improve harvesting efficiency and mechanization rate while reducing costs. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a harvesting robot end effector and execution method with rotation and telescopic functions, which can improve harvesting efficiency and is applicable to the harvesting of various types of fruits and vegetables.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] On one hand, the present invention provides an end effector for a harvesting robot with rotation and telescopic functions, which is disposed at the end of the robotic arm of the harvesting robot and includes a clamping part, a first driving mechanism and a second driving mechanism; the first driving mechanism is connected to the clamping part and is used to drive the clamping part to perform rotation and / or telescopic movements; the second driving mechanism is connected to the first driving mechanism and is used to drive the first driving mechanism to pitch up and down and / or swing left and right.

[0008] Furthermore, the second drive mechanism includes a fixed frame, a third drive motor, a transmission assembly, and a fourth drive motor;

[0009] The third drive motor is fixedly connected to the fixed frame and is used to drive the fourth drive motor to pitch up and down through the transmission assembly;

[0010] The fourth drive motor is movably connected to the fixed frame, and the output shaft of the fourth drive motor is fixedly connected to the first drive mechanism to drive the first drive mechanism to swing left and right.

[0011] Furthermore, the transmission assembly includes a first rotating wheel, a second rotating wheel, and a transmission belt;

[0012] The first rotating wheel is fixedly connected to the output shaft of the third drive motor, and the second rotating wheel is fixedly connected to the fourth drive motor;

[0013] When the third drive motor starts working, the fourth drive motor achieves pitching by cooperating with the first rotating wheel, the second rotating wheel and the transmission belt.

[0014] Furthermore, the fixing frame is a U-shaped frame; the third drive motor is fixedly installed on the side wall or bottom of the U-shaped frame, the fourth drive motor is hinged to the two side walls of the U-shaped frame, and the output shaft of the fourth drive motor can pitch up and down in the space area where the opening of the U-shaped frame is located.

[0015] Furthermore, the first drive mechanism includes a first mounting bracket and a ball screw spline mechanism mounted within the first mounting bracket;

[0016] The ball screw spline mechanism includes a screw spline shaft, a first driven wheel and a second driven wheel symmetrically distributed on the screw spline shaft, and a first drive motor and a second drive motor symmetrically distributed on one side of the first mounting bracket.

[0017] The first drive motor drives the first drive wheel to rotate, and the first drive wheel drives the first driven wheel to rotate; the second drive motor drives the second drive wheel to rotate, and the second drive wheel drives the second driven wheel to rotate; the first driven wheel and the second driven wheel are located on the other side of the first mounting bracket;

[0018] The lead screw spline shaft has several sets of parallel grooves along the axial direction and a spiral groove along the helical direction; a ball screw nut and a spline nut are also installed on the lead screw spline shaft respectively. The ball screw nut is connected to the first driven wheel through a flange, and the spline nut is connected to the second driven wheel through a flange.

[0019] When either the first driven wheel or the second driven wheel rotates while the other driven wheel remains stationary, the lead screw spline shaft extends / retracts axially under the rotation of the ball screw nut or spline nut.

[0020] When the first driven wheel and the second driven wheel rotate in the same direction and at the same speed, the lead screw spline shaft rotates under the combined action of the ball screw nut and the spline nut.

[0021] Furthermore, when the second driven wheel stops rotating and only the first driven wheel drives the ball screw nut to rotate, the screw spline shaft moves linearly along the axial direction; when the first driven wheel stops rotating and only the second driven wheel drives the spline nut to rotate, the screw spline shaft moves helically.

[0022] Furthermore, the first drive mechanism includes an encoder for measuring the rotational displacement of the first drive motor and the second drive motor; optionally, the encoder has a power-off memory function.

[0023] Furthermore, the clamping part is a chuck or suction cup fixedly installed at the end of the lead screw spline shaft.

[0024] Furthermore, the first mounting bracket includes a housing installed outside the ball screw nut and spline nut, and also includes a first mounting bracket for placing the first drive motor and the second drive motor; the first mounting bracket has a U-shaped cross section and is integrally formed from a rectangular plate and trapezoidal plates located on both sides of the rectangular plate; the first drive motor and the second drive motor are respectively mounted on corresponding motor brackets, and the motor brackets are fixedly mounted on the rectangular plate by bolts.

[0025] Furthermore, the outer surface of the rectangular plate and the outer surface of the outer shell are provided with mark recognition points to improve the positioning accuracy of the vision system of the harvesting robot and increase the system operating speed.

[0026] On the other hand, the present invention also provides an execution method for an end effector of a harvesting robot with rotation and telescopic functions. When the end effector of the harvesting robot receives a harvesting command and performs a harvesting action, the specific execution process is as follows:

[0027] 1) The end effector of the harvesting robot moves to the harvesting position: the rotation of the third drive motor in the second drive mechanism drives the fourth drive motor, which in turn drives the first drive mechanism to pitch up and down; under the action of the fourth drive motor, the first drive mechanism is driven to swing left and right.

[0028] 2) The clamping part of the end effector of the harvesting robot extends to clamp the fruits and vegetables to be harvested: the first driven wheel in the first drive mechanism drives the ball screw nut to rotate, so that the screw spline shaft extends axially, thereby driving the clamping part to extend; or, the second driven wheel in the first drive mechanism drives the spline nut to rotate, so that the screw spline shaft extends spirally axially, thereby driving the clamping part to extend.

[0029] 3) The clamping part of the end effector of the harvesting robot drives the fruit and vegetables to be harvested to rotate, so that the fruit and vegetables to be harvested are separated from the fruit stem: the first driven wheel drives the ball screw nut to rotate and the second driven wheel drives the spline nut to rotate in the same direction and at the same speed, so that the screw spline shaft rotates. The clamping part further drives the fruit and vegetables to be harvested to rotate, thus completing the separation of the fruit and vegetables from the fruit stem.

[0030] 4) The clamping part of the end effector of the harvesting robot retracts: the first driven wheel drives the ball screw nut to rotate, causing the screw spline shaft to retract axially, thereby causing the clamping part to retract; or, the second driven wheel drives the spline nut to rotate, causing the screw spline shaft to spirally retract axially, thereby causing the clamping part to retract.

[0031] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects: When the actuator receives the picking instruction issued by the picking robot, the second drive mechanism drives the first drive mechanism to pitch up and down and / or swing left and right to ensure that the clamping part reaches the picking position for picking fruits and vegetables. When the clamping part reaches the picking position, the ball screw nut is first rotated by the first driven wheel (while the second driven wheel remains stationary) or the spline nut is rotated by the second driven wheel (while the first driven wheel remains stationary), causing the screw spline shaft to extend axially. Then, the ball screw nut and spline nut rotate in the same direction and at the same speed by the first driven wheel and the second driven wheel, respectively, causing the screw spline shaft to rotate. This further rotates the fruit or vegetable to be picked, causing it to detach from the stem. Finally, the ball screw nut is rotated by the first driven wheel (while the second driven wheel remains stationary) or the spline nut is rotated by the second driven wheel (while the first driven wheel remains stationary), causing the screw spline shaft to retract axially, completing the picking process.

[0032] This actuator, without the need for an eccentric blade, can harvest fruits and vegetables, especially clustered fruits and vegetables such as jujubes and oranges, simply by using the cooperation of the first drive mechanism, the second drive mechanism, and the clamping part. The first drive mechanism uses a ball screw spline mechanism, which enables the clamping part to complete linear, helical, and rotational movements. In conjunction with the second drive mechanism, the first drive mechanism can achieve pitching and / or swaying, which is beneficial for the clamping part to make small-range angle adjustments at the part to be harvested, avoiding accidental damage to nearby unripe fruits and vegetables. Attached Figure Description

[0033] The accompanying drawings are incorporated in and form part of this specification, and together with the description serve to explain the principles of the invention.

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 A schematic diagram of the end effector of the harvesting robot with rotation and telescopic function provided by the present invention;

[0036] Figure 2 A schematic diagram of the first drive mechanism in the end effector of the harvesting robot with rotation and telescopic function provided by the present invention;

[0037] Figure 3 This is a schematic diagram of the second drive mechanism in the end effector of the harvesting robot with rotation and telescopic function provided by the present invention.

[0038] The components are: 1. Clamping part; 2. First drive mechanism; 21. Lead screw spline shaft; 22. First driven wheel; 23. Second driven wheel; 24. First driving wheel; 25. Second driving wheel; 26. Housing; 27. Second mounting bracket; 271. Rectangular plate; 272. Trapezoidal plate; 28. Mark identification point; 3. Second drive mechanism; 31. Third drive motor; 32. Fourth drive motor; 33. First rotating wheel; 34. Second rotating wheel. Detailed Implementation

[0039] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of structures consistent with some aspects of the invention as detailed in the appended claims.

[0040] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0041] Example 1

[0042] See Figure 1-3 As shown, the present invention provides an end effector for a harvesting robot with rotation and telescopic functions, which is disposed at the end of the robotic arm of the harvesting robot and includes a clamping part 1, a first driving mechanism 2 and a second driving mechanism 3; the first driving mechanism 2 is connected to the clamping part 1 and is used to drive the clamping part 1 to perform rotation and / or telescopic movements; the second driving mechanism 3 is connected to the first driving mechanism 2 and is used to drive the first driving mechanism 2 to pitch up and down and / or swing left and right.

[0043] The second drive mechanism 3 includes a fixed frame, a third drive motor 31, a transmission assembly, and a fourth drive motor 32.

[0044] The third drive motor 31 is fixedly connected to the fixed frame and is used to drive the fourth drive motor 32 to pitch up and down through the transmission component, thereby driving the first drive mechanism 2, which is fixedly connected to the output shaft of the fourth drive motor 32, to pitch up and down.

[0045] The fourth drive motor 32 is movably connected to the fixed frame, and the output shaft of the fourth drive motor 32 is fixedly connected to the first drive mechanism 2 to drive the first drive mechanism 2 to swing left and right.

[0046] Furthermore, the transmission assembly includes a first rotating wheel 33, a second rotating wheel 34, and a transmission belt; optionally, the transmission belt is a synchronous belt or a belt.

[0047] The first rotating wheel 33 is fixedly connected to the output shaft of the third drive motor 31, and the second rotating wheel 34 is fixedly connected to the fourth drive motor 32; combined Figure 1 and Figure 3 It should be understood that the second rotating wheel 34 is fixedly connected to the housing of the fourth drive motor 32;

[0048] When the third drive motor 31 starts working, the fourth drive motor 32 tilts up and down through the cooperation of the first rotating wheel 33, the second rotating wheel 34, and the transmission belt, thereby driving the first drive mechanism 2, which is fixedly connected to the output shaft of the fourth drive motor 32, to tilt up and down. Preferably, the tilt angle of the fourth drive motor 32 is ±30°.

[0049] Furthermore, the fixing frame is a U-shaped frame; the third drive motor 31 is fixedly installed on the side wall or bottom of the U-shaped frame, and the fourth drive motor 32 is hinged to both side walls of the U-shaped frame, and the output shaft of the fourth drive motor 32 can pitch up and down in the space where the opening of the U-shaped frame is located. Figure 3 It should be understood that when the fixing frame is a U-shaped frame, the optimal positional arrangement of the third drive motor 31, the fourth drive motor 32, and the transmission assembly including the first rotating wheel 33, the second rotating wheel 34, and the transmission belt in the second drive mechanism 3 is as follows:

[0050] The bottom area of ​​the U-shaped frame is horizontally supported by the third drive motor 31, and the top area is vertically supported by the fourth drive motor 32; the first rotating wheel 33 is fixed on the output shaft of the third drive motor 31, and the second rotating wheel 34 is fixed on the base of the fourth drive motor 32; the transmission belt is wound around the first rotating wheel 33 and the second rotating wheel 34.

[0051] The first drive mechanism 2 includes a first mounting bracket and a ball screw spline mechanism installed in the first mounting bracket;

[0052] The ball screw spline mechanism includes a screw spline shaft 21, a first driven wheel 22 and a second driven wheel 23 symmetrically distributed on the screw spline shaft 21, and a first drive motor and a second drive motor symmetrically distributed on one side of the first mounting bracket.

[0053] The first drive motor drives the first drive wheel 24 to rotate, and the first drive wheel 24 drives the first driven wheel 22 to rotate; the second drive motor drives the second drive wheel 25 to rotate, and the second drive wheel 25 drives the second driven wheel 23 to rotate; the first driven wheel 22 and the second driven wheel 23 are located on the other side of the first mounting bracket;

[0054] The lead screw spline shaft 21 has several sets of parallel grooves along the axial direction and a spiral groove along the helical direction; a ball screw nut and a spline nut are also installed on the lead screw spline shaft 21 respectively. The ball screw nut is connected to the first driven wheel 22 through a flange, and the spline nut is connected to the second driven wheel 23 through a flange.

[0055] When either the first driven wheel 22 or the second driven wheel 23 rotates while the other driven wheel remains stationary, the lead screw spline shaft 21 extends / retracts axially under the rotation of the ball screw nut or spline nut.

[0056] When the first driven wheel 22 and the second driven wheel 23 rotate in the same direction and at the same speed, the lead screw spline shaft 21 rotates under the combined action of the ball screw nut and the spline nut.

[0057] Furthermore, when the first driven wheel 22 and the second driven wheel 23 rotate in the same direction and there is a certain speed difference between them, the lead screw spline shaft 21 performs helical motion under the combined action of the ball screw nut and the spline nut. In the technical solution of the end effector of the harvesting robot provided by the present invention, the first drive mechanism 2 innovatively uses a ball screw spline mechanism as the drive device, which can achieve small size and lighter weight, making it easier to reach into the fruit tree for harvesting.

[0058] In some embodiments, the first driving wheel 24 drives the first driven wheel 22 to rotate via belt drive, and the second driving wheel 25 drives the second driven wheel 23 to rotate via belt drive. It should be noted that, in addition to belt drive, synchronous belt or magnetic drive can also be used.

[0059] In some embodiments, the lead screw spline shaft 21 extends / retracts axially, specifically: when the second driven wheel 23 stops rotating and only the first driven wheel 22 drives the ball screw nut to rotate, the lead screw spline shaft 21 moves linearly axially; when the first driven wheel 22 stops rotating and only the second driven wheel 23 drives the spline nut to rotate, the lead screw spline shaft 21 moves helically.

[0060] In some embodiments, the first drive mechanism includes an encoder for measuring the rotational displacement of the first drive motor and the second drive motor; optionally, the encoder has a power-off memory function.

[0061] In some embodiments, the clamping part 1 is a gripper or a suction cup fixedly mounted on the end of the lead screw spline shaft 21. In some embodiments, the gripper can be an electric gripper or a pneumatic gripper; the electric gripper is preferably a servo-driven electric gripper. In some embodiments, the suction cup can be a vacuum suction cup device.

[0062] Preferably, a channel can be opened axially at the center of the lead screw spline shaft 21 to avoid the connecting pipe / line in the chuck or suction cup being affected by the extension / retraction / rotation of the lead screw spline shaft 21, thereby extending the service life of the pipe / line.

[0063] In some exemplary embodiments, the first mounting bracket includes a housing mounted on the outside of the ball screw nut and the spline nut, and also includes a first mounting bracket for fixing the first drive motor and the second drive motor. The first mounting bracket has a U-shaped cross section and is integrally formed by a rectangular plate 271 and trapezoidal plates 272 located on both sides of the rectangular plate 271. The first drive motor and the second drive motor are respectively mounted on corresponding motor brackets, and the motor brackets are fixedly mounted on the rectangular plate 271 by bolts.

[0064] To improve the positioning accuracy of the vision system of the harvesting robot, mark recognition points are provided on the outer surface of the rectangular plate 271 and the outer surface of the shell 26; at the same time, the spatial coordinate points of the mark recognition points can be read by the camera, and the computing speed of the entire robotic arm system can be further improved by the spatial coordinate points.

[0065] In addition, this embodiment also includes a fruit and vegetable collection mechanism that cooperates with the actuator. The fruit and vegetable collection mechanism includes a fruit and vegetable turnover frame, which is connected to the fruit and vegetable collection frame via a transmission pipe. To reduce bumps and drops on the fruits and vegetables during collection, the fruit and vegetable turnover frame, transmission pipe, and fruit and vegetable collection frame are all made of soft cushioning material to prevent damage from bumps during harvesting.

[0066] Example 2 (The following description uses a spatial coordinate system to define the execution method of the above-mentioned actuator. Since the execution process involves 3 "rotations" and 1 "extension", it can achieve a certain working range in space, which facilitates the harvesting robot to perform harvesting operations.)

[0067] Based on Embodiment 1, this embodiment also provides an execution method for an end effector of a harvesting robot with rotational and telescopic functions. A three-dimensional coordinate system is established with the center of the fourth drive motor 32 as the origin. The rotation direction of the fourth drive motor 32 is defined as the Z-axis, the length direction of the U-shaped frame is defined as the Y-axis, and the straight line direction determined by the hinge point between the fourth drive motor 32 and the U-shaped frame is defined as the X-axis. When the end effector of the harvesting robot receives a harvesting command and performs a harvesting action, the specific execution process is as follows:

[0068] 1) The end effector of the harvesting robot moves to the harvesting position: the rotation of the third drive motor 31 in the second drive mechanism 3 drives the fourth drive motor 32, which in turn drives the first drive mechanism 2 to pitch up and down (i.e., along the direction of movement). Figure 1 In the Z-axis direction, the pitch angle is adjusted within a small range, approximately 30° (this is the first "rotation"); under the action of the fourth drive motor 32, the first drive mechanism 2 is driven to swing left and right (i.e., along the Z-axis). Figure 1 It swings along the Y-axis (this is the second "rotation");

[0069] 2) The clamping part 1 of the end effector of the harvesting robot extends to clamp the fruits and vegetables to be harvested: the first driven wheel 22 in the first drive mechanism 2 drives the ball screw nut to rotate, so that the screw spline shaft 21 extends axially, thereby driving the clamping part 1 to extend; or, the second driven wheel 23 in the first drive mechanism 2 drives the spline nut to rotate, so that the screw spline shaft 21 extends spirally axially, thereby driving the clamping part 1 to extend.

[0070] 3) The clamping part 1 of the end effector of the harvesting robot drives the fruit and vegetables to be harvested to rotate, so that the fruit and vegetables to be harvested are separated from the fruit stem: the first driven wheel 22 drives the ball screw nut to rotate and the second driven wheel 23 drives the spline nut to rotate in the same direction and at the same speed, so that the screw spline shaft 21 rotates (this is the third "rotation"), and the clamping part 1 further drives the fruit and vegetables to be harvested to rotate, so as to complete the separation of the fruit and vegetables from the fruit stem;

[0071] 4) The clamping part 1 of the end effector of the harvesting robot retracts: the ball screw nut is rotated by the first driven wheel 23, causing the screw spline shaft 21 to retract axially, thereby causing the clamping part 1 to retract; or, the spline nut is rotated by the second driven wheel 23, causing the screw spline shaft 21 to retract helically axially, thereby causing the clamping part 1 to retract.

[0072] This actuator, without the need for an eccentric blade, can harvest fruits and vegetables, especially clustered fruits and vegetables such as jujubes and oranges, simply by using the cooperation of the first drive mechanism 2, the second drive mechanism 3, and the clamping part 1. The first drive mechanism 2 adopts a ball screw spline mechanism, which enables the clamping part 1 to complete linear, helical, and rotational movements. In conjunction with the second drive mechanism 3, the first drive mechanism 2 can achieve pitching and / or swaying, which is beneficial for the clamping part 1 to make small-range angle adjustments at the part to be harvested, avoiding accidental damage to nearby unripe fruits and vegetables.

[0073] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention.

[0074] It should be understood that the present invention is not limited to the content already described above, and various modifications and changes can be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. An end effector for a harvesting robot with rotational and telescopic functions, disposed at the end of the robotic arm of the harvesting robot, characterized in that, It includes a clamping part (1), a first driving mechanism (2) and a second driving mechanism (3); the first driving mechanism (2) is connected to the clamping part (1) and is used to drive the clamping part (1) to rotate and / or extend; the second driving mechanism (3) is connected to the first driving mechanism (2) and is used to drive the first driving mechanism (2) to pitch up and down and / or swing left and right. The second drive mechanism (3) includes a fixed frame, a third drive motor (31), a transmission assembly, and a fourth drive motor (32); The third drive motor (31) is fixedly connected to the fixed frame and is used to drive the fourth drive motor (32) to pitch up and down through the transmission assembly; The fourth drive motor (32) is movably connected to the fixed frame, and the output shaft of the fourth drive motor (32) is fixedly connected to the first drive mechanism (2) to drive the first drive mechanism (2) to swing left and right. The transmission assembly includes a first rotating wheel (33), a second rotating wheel (34), and a transmission belt; The first rotating wheel (33) is fixedly connected to the output shaft of the third drive motor (31), and the second rotating wheel (34) is fixedly connected to the fourth drive motor (32); When the third drive motor (31) starts working, the fourth drive motor (32) achieves pitch by cooperating with the first rotating wheel (33), the second rotating wheel (34) and the transmission belt; The first drive mechanism (2) includes a first mounting bracket and a ball screw spline mechanism installed in the first mounting bracket; The ball screw spline mechanism includes a screw spline shaft (21), a first driven wheel (22) and a second driven wheel (23) symmetrically distributed on the screw spline shaft (21), and a first drive motor and a second drive motor symmetrically distributed on one side of the first mounting bracket; The first drive motor drives the first drive wheel (24) to rotate, and the first drive wheel (24) drives the first driven wheel (22) to rotate; the second drive motor drives the second drive wheel (25) to rotate, and the second drive wheel (25) drives the second driven wheel (23) to rotate; the first driven wheel (22) and the second driven wheel (23) are located on the other side of the first mounting bracket; The lead screw spline shaft (21) has several sets of parallel grooves along the axial direction and a spiral groove along the helical direction; a ball screw nut and a spline nut are also installed on the lead screw spline shaft (21), the ball screw nut is connected to the first driven wheel (22) through a flange, and the spline nut is connected to the second driven wheel (23) through a flange. When either the first driven wheel (22) or the second driven wheel (23) rotates while the other driven wheel remains stationary, the lead screw spline shaft (21) extends / retracts axially under the rotation of the ball screw nut or spline nut. When the first driven wheel (22) and the second driven wheel (23) rotate in the same direction and at the same speed, the lead screw spline shaft (21) rotates under the combined action of the ball screw nut and the spline nut.

2. The end effector of the harvesting robot according to claim 1, characterized in that, The fixed frame is a U-shaped frame; the third drive motor (31) is fixedly installed on the side wall or bottom of the U-shaped frame, the fourth drive motor (32) is hinged to the two side walls of the U-shaped frame, and the output shaft of the fourth drive motor (32) can pitch up and down in the space area where the opening of the U-shaped frame is located.

3. The end effector of the harvesting robot according to claim 1, characterized in that, When the second driven wheel (23) stops rotating and only the first driven wheel (22) drives the ball screw nut to rotate, the screw spline shaft (21) moves linearly along the axial direction; when the first driven wheel (22) stops rotating and only the second driven wheel (23) drives the spline nut to rotate, the screw spline shaft (21) moves helically.

4. The end effector of the harvesting robot according to claim 1, characterized in that, The first drive mechanism includes an encoder for measuring the rotational displacement of the first drive motor and the second drive motor.

5. The end effector of the harvesting robot according to claim 1, characterized in that, The clamping part (1) is a chuck or suction cup that is fixedly installed at the end of the lead screw spline shaft (21).

6. The end effector of the harvesting robot according to claim 1, characterized in that, The first mounting bracket includes a housing (26) installed outside the ball screw nut and spline nut, and a second mounting bracket (27) for placing the first drive motor and the second drive motor; the second mounting bracket (27) has a U-shaped cross section and is integrally formed by a rectangular plate (271) and trapezoidal plates (272) located on both sides of the rectangular plate (271); the first drive motor and the second drive motor are respectively mounted on corresponding motor brackets, and the motor brackets are fixedly mounted on the rectangular plate (271) by bolts.

7. The execution method of the end effector of the harvesting robot according to any one of claims 1-6, characterized in that, When the end effector of the harvesting robot receives a harvesting command and performs the harvesting action, the specific execution process is as follows: 1) The end effector of the picking robot moves to the picking position: the rotation of the third drive motor (31) in the second drive mechanism (3) drives the fourth drive motor (32) to drive the first drive mechanism (2) to pitch up and down; under the action of the fourth drive motor (32), the first drive mechanism (2) is driven to swing left and right. 2) The clamping part (1) of the end effector of the harvesting robot extends to clamp the fruits and vegetables to be harvested: the ball screw nut is rotated by the first driven wheel (22) in the first drive mechanism (2), so that the screw spline shaft (21) extends along the axial direction, thereby driving the clamping part (1) to extend; or, the spline nut is rotated by the second driven wheel (23) in the first drive mechanism (2), so that the screw spline shaft (21) extends spirally along the axial direction, thereby driving the clamping part (1) to extend; 3) The clamping part (1) of the end effector of the harvesting robot drives the fruit and vegetables to be harvested to rotate, so that the fruit and vegetables to be harvested are separated from the fruit stem: the first driven wheel (22) drives the ball screw nut to rotate and the second driven wheel (23) drives the spline nut to rotate in the same direction and at the same speed, so that the screw spline shaft (21) rotates. The clamping part (1) further drives the fruit and vegetables to be harvested to rotate, so as to complete the separation of the fruit and vegetables from the fruit stem. 4) The clamping part (1) of the end effector of the harvesting robot retracts: the ball screw nut is rotated by the first driven wheel (22), so that the screw spline shaft (21) retracts along the axial direction, thereby driving the clamping part (1) to retract; or, the spline nut is rotated by the second driven wheel (23), so that the screw spline shaft (21) retracts along the axial direction, thereby driving the clamping part (1) to retract.

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