Grab-and-rotate coordinated apple picking end effector

Abstract

This utility model discloses a gripping and rotating coordinated apple-picking end effector, installed at the end of a picking robotic arm, comprising a cylindrical housing, a linear motor, a transmission mechanism, and a gripper assembly. The transmission mechanism converts the linear motion output by the linear motor into linear and rotational motions. The gripper assembly opens and rotates via an upward motion, and closes and rotates in the opposite direction via a downward motion to twist and break the fruit stem. The transmission mechanism uses a pin sleeve in cooperation with a central groove shaft, and achieves step-by-step movement through a spiral groove and a limiting groove structure. The gripper assembly completes clamping and twisting through a guide ridge and a hinge seat. This design simplifies the drive structure, reduces costs, improves reliability and picking efficiency, and is suitable for apple picking scenarios with short stems and dense branches.

Description

Technical Field

[0001] This utility model belongs to the field of agricultural machinery technology, specifically relating to a compact gripping and rotating collaborative harvesting execution unit for automated fruit and vegetable harvesting, which is particularly suitable for fruit and vegetable harvesting scenarios with short fruit stalks and complex growing environments (such as dense branches). Background Technology

[0002] The advancement of agricultural modernization has significantly increased the demands for mechanization and intelligentization in fruit and vegetable harvesting. Traditional manual harvesting methods, due to their low efficiency, heavy labor, and high costs, are increasingly unable to meet the needs of industrial development. Although existing harvesting equipment (such as vibrating or semi-automatic machines) has achieved some degree of manual labor substitution, their application still faces significant shortcomings: limited adaptability, high damage rates, and insufficient level of intelligence. Especially when handling diverse fruit and vegetable varieties, shapes, or ripeness levels, the structural rigidity of the actuators and the complex transmission of the power system constitute the core challenges to improving equipment performance.

[0003] The applicant's previous fruit and vegetable harvesting actuator, integrating gripping, twisting, and cutting functions, relied on multi-stage transmission structures (such as gear trains and linkage mechanisms) to collaboratively drive the grippers to complete compound actions. This type of solution achieved sequential action coordination through a pre-set mechanical linkage path, functionally meeting the requirements for gripping and separating fruit stems. Its core value lies in effectively improving harvesting efficiency and providing an early structural prototype for automated harvesting equipment. However, this design paradigm has significant drawbacks:

[0004] I. Structural Complexity and Manufacturing Challenges

[0005] The applicant's previous technology focused on a "multi-stage transmission" design paradigm, achieving compound actions through complex linkage combinations. This resulted in a large number of components and stringent assembly tolerance requirements (for example, insufficient gear meshing precision could easily lead to motion interference or jamming). In contrast, this application establishes a technical route that eliminates the need for complex transmission mechanisms to achieve step-by-step actions. It uses helical grooves and related limiting designs to replace multi-link transmissions to achieve grasping and torsional actions.

[0006] In the past, when developing composite motion actuators, the technical approach followed the traditional idea of ​​"functional integration and structural superposition," prioritizing the comprehensiveness of motion while neglecting cost and reliability. This resulted in a more complex drive system (increasing processing and assembly costs by 30% to 50%), while also reducing the reliability and maintainability of the equipment.

[0007] II. Problems of Insufficient Adaptability

[0008] Previous technologies struggled to adapt to different harvesting targets. Key parameters of their actuators (such as gripper closing force and torsion angle) were difficult to adjust, resulting in high redesign costs. Furthermore, they lacked adaptability to the biomechanical characteristics of fruits / stems (such as hardness and brittleness), requiring a complete redesign of the transmission mechanism whenever the torsion angle needed adjustment. In contrast, this application employs a "step-by-step action – mechanical limit" design, enabling independent control of the gripper opening and closing and rotational movements. It can adapt to different fruit and vegetable characteristics by replacing the central groove shaft and cylindrical shell.

[0009] III. Defects in Transmission Stability and Motion Accuracy

[0010] Previous designs by the applicant focused on a "linkage transmission - overall rotation" structural design. The gripper drive relied on a linkage mechanism, and the turntable rotation was rigidly connected to the cylindrical shell, resulting in large transmission clearance (>0.2mm) and low rotational accuracy (angular error >1°). This made it prone to jamming or component interference in areas with dense branches. In contrast, this application establishes a "linear bearing - dynamic-static separation" technical approach, replacing the linkage transmission with linear bearings. The inner ring of the turntable is separated from the outer shell through bearings, improving motion stability and accuracy.

[0011] In traditional mechanical design, linkage mechanisms are widely used in the actuator field due to their simple structure and low cost. This has led to a fixed perception in the industry of the "limitations of linkage transmission," neglecting the potential of linear bearings in low-friction, high-precision transmission, as well as the role of the turntable structure separation design in improving stability.

[0012] The aforementioned inherent defects constitute the core obstacle to the large-scale promotion of the previous integrated gripping and rotating actuator: First, its complex configuration (due to the transmission mechanism with many parts) significantly increases manufacturing and maintenance costs; second, it cannot flexibly respond to the differences in biomechanical characteristics of different fruit and vegetable varieties and individual maturity, and the cost of replacing different parts to achieve the harvesting of different fruits and vegetables is very high, which limits the applicability of the equipment in diversified orchard scenarios.

[0013] To overcome the aforementioned bottlenecks, there is an urgent need to develop a new type of actuator with highly integrated structure, precise motion control, and environmental adaptability. Its core lies in reconstructing the power transmission topology and innovating a composite motion coordination mechanism (which is also fundamentally different from the applicant's previous similar designs), thereby eradicating the structural problems of existing technologies. Utility Model Content

[0014] The purpose of this utility model is to provide a gripping and rotating coordinated apple harvesting end effector. It addresses the technical problems of existing fruit and vegetable harvesting actuators that rely on complex linkage transmissions, resulting in structural redundancy (many parts, high assembly precision requirements), high manufacturing costs (increased hardware and assembly costs due to the large number of parts), low reliability (linkages are prone to jamming, and there is a high risk of motion interference), and insufficient harvesting efficiency (simultaneous execution of compound actions is prone to conflict). By designing a rotating groove shaft and a limiting structure, the linear motion is converted into the opening, closing, and rotating actions of the gripper in stages, thereby simplifying the transmission structure, reducing costs, and improving harvesting efficiency and reliability.

[0015] To achieve the above objectives, this utility model provides a gripping and rotating coordinated apple picking end effector for picking apples by being installed at the end of a picking robotic arm, comprising a cylindrical housing, a linear motor, a transmission mechanism, and a gripper assembly;

[0016] The lower middle part of the transmission mechanism is located inside the cylindrical housing, and the top of the transmission mechanism is hinged to the gripper assembly.

[0017] The cylindrical housing is equipped with a motion limiting structure that restricts the movement of the transmission mechanism. The motion limiting structure is used to enable the transmission mechanism to convert the linear motion output by the linear motor into linear motion and rotational motion.

[0018] The gripper assembly opens and then rotates under the upward linear motion output by the transmission mechanism.

[0019] The gripper assembly closes and then rotates in the opposite direction under the downward linear motion output by the transmission mechanism, thereby twisting off the apple stem.

[0020] The transmission mechanism includes a pin sleeve and a central groove shaft inserted in the pin sleeve. The outer surface of the lower middle part of the central groove shaft is provided with a spiral groove. A pin is installed on the side wall of the pin sleeve, and the inner end of the pin extends into the spiral groove.

[0021] A linear motor is installed at the bottom of the cylindrical housing. The output end of the linear motor is connected to the pin sleeve and is used to drive the pin sleeve to move up and down.

[0022] A limiting protrusion is radially connected to the middle of the central groove shaft. The diameter of the central groove shaft above the limiting protrusion is smaller than the diameter of the central groove shaft below it. The central groove shaft above the limiting protrusion is called the reduced diameter section.

[0023] The upper part of the inner wall of the cylindrical shell is radially recessed and provided with an upward limiting groove, a circumferential limiting groove and a downward limiting groove that match the limiting protrusion. The upward limiting groove, the circumferential limiting groove and the downward limiting groove are arranged adjacent to each other from top to bottom.

[0024] When the central groove shaft is at the lower limit position, the limiting protrusion is located in the downward limiting groove;

[0025] When the central groove shaft is at its upper limit position, the limiting protrusion is located within the upper limiting groove;

[0026] The motion limiting structure includes the upward limiting groove, the circumferential limiting groove, and the downward limiting groove.

[0027] The central groove shaft has three guide ridges on the diameter reduction section limiting protrusion. Each guide ridge is evenly distributed around the diameter reduction section. Each guide ridge is fixedly connected to an upper hinge seat at its top.

[0028] The gripper assembly includes a limit bearing installed at the top of the cylindrical housing. The outer ring of the limit bearing is fixedly connected to the cylindrical housing. An inner ring clamping plate is fixedly connected to the inner ring of the cylindrical housing. The inner ring clamping plate is provided with three guide grooves. The guide ridges and guide grooves are matched one by one, and each guide ridge is inserted into the corresponding guide groove.

[0029] The inner ring clamp is fixedly connected to the bottom ring. The bottom ring is provided with three lower hinge seats corresponding to each guide ridge. Each lower hinge seat is hinged to a gripper rod. Each gripper rod extends upward and is connected to a gripping groove for gripping apples. Each gripper rod is connected to a linear bearing. Each linear bearing is connected to a bearing sleeve. The bearing sleeve encloses the linear bearing. Each bearing sleeve is connected to a hinge plate. The hinge plate corresponds to the upper hinge seat. The hinge plate is inserted into the corresponding upper hinge seat and rotates with the upper hinge seat through a pin.

[0030] The lower hinge seats correspond one-to-one with the upper hinge seats, and each lower hinge seat forms a concentric outer circle, while each upper hinge seat forms a concentric inner circle. The centers of both the concentric outer and inner circles are located on the axis of the central groove shaft.

[0031] The inner ring clamp is provided with two plates spaced apart at the top and bottom.

[0032] The circumferential angle of the spiral groove is 360-1080 degrees.

[0033] This utility model has the following advantages:

[0034] This invention no longer uses the previous linkage mechanism design, and the number of moving parts is greatly reduced. Through single motor drive and mechanical step-by-step action design, it achieves simplified drive structure, reduced manufacturing cost (reduced number of parts leads to reduced hardware and assembly costs), improved reliability (significantly reduced risk of motion interference) and improved picking efficiency (shortened execution time of compound actions).

[0035] The transmission mechanism has a simple structure, few parts, and low cost. It can easily convert the linear motion output by the linear motor into sequential linear and rotary motions without the risk of linkage jamming, and the action is accurate and rapid.

[0036] The gripper assembly has a simple structure. When the linear bearings and bearing sleeves move upward with the central groove axis, they naturally constrain the gripper bars to open, allowing them to cover the target apple. When the linear bearings and bearing sleeves move downward with the central groove axis, they naturally constrain the gripper bars to retract, thus clamping the target apple. The gripper assembly can rotate together with the central groove axis, thereby achieving the action of twisting the apple.

[0037] Two inner clamping plates enhance structural strength. The angle of the spiral grooves ensures that the apple stem can be twisted at an angle of 360 to 1080 degrees, allowing the apple to be broken by the pulling action of the harvesting robotic arm.

[0038] By changing different central groove shafts (different spiral groove angles) and matching cylindrical shells (matching the torsion angle) with axial length (height) of the circumferential limiting groove, the angle at which the fruit stalk is twisted can be easily controlled to meet the needs of harvesting fruits and vegetables with different characteristics. Attached Figure Description

[0039] Figure 1 This is a three-dimensional structural diagram of the present invention, wherein the cylindrical shell and bearing sleeve are made transparent to show their internal structure.

[0040] Figure 2 This is a schematic diagram of the structure of this utility model.

[0041] Figure 3 yes Figure 2 AA sectional view.

[0042] Figure 4 yes Figure 2 BB cross-sectional view.

[0043] Figure 5 yes Figure 2 CC section view.

[0044] Figure 6 This is a three-dimensional structural diagram of the present invention.

[0045] Figure 7 This is a top view of the inner ring clamping plate.

[0046] 1. Cylindrical shell 1

[0047] Installation location: It serves as the housing for the actuator and is installed at the end of the harvesting robotic arm.

[0048] Structural relationship: The upper part of the inner wall is provided with an upward limiting groove 9, a circumferential limiting groove 10, and a downward limiting groove 11. A linear motor 2 is installed at the bottom and a limiting bearing 13 is installed at the top.

[0049] Working principle: The internal limiting groove constrains the motion state (linear or rotational) of the transmission mechanism, providing support and motion guidance for each component.

[0050] Technical function: Integrating the transmission mechanism and gripper assembly to achieve motion trajectory control and ensure the overall structural stability of the actuator.

[0051] 2. Linear Motor 2

[0052] Installation location: Fixed to the bottom of the cylindrical shell 1.

[0053] Structural relationship: The output end is connected to the pin sleeve 3, driving it to move up and down.

[0054] Working principle: It provides axial power and indirectly drives the linear and rotary motion of the central groove shaft 4 by controlling the lifting and lowering of the pin sleeve 3.

[0055] Technical function: As a single power source, it replaces the traditional multi-motor design, simplifies the drive system, reduces costs, and improves reliability.

[0056] 3. Pin sleeve 3

[0057] Installation position: It is sleeved on the outside of the central groove shaft 4 and located in the lower part of the cylindrical shell 1.

[0058] Structural relationship: Pin 6 is installed on the side wall, and the inner end of Pin 6 extends into the spiral groove 5 of the central groove shaft 4; the bottom is connected to the output end of the linear motor 2.

[0059] Working principle: As the linear motor 2 moves up and down, the linear motion is converted into the rotational motion of the central groove shaft 4 through the cooperation of the pin 6 and the spiral groove 5.

[0060] Technical function: It transmits power and realizes the conversion of motion forms, and is the core component of the transmission mechanism.

[0061] 4. Center groove shaft 4

[0062] Installation position: Inserted into the pin sleeve 3, with the lower middle part located inside the cylindrical housing 1, and the top hinged to the gripper assembly.

[0063] Structural relationship: The lower outer surface is provided with a spiral groove 5, the middle radially connected with a limiting protrusion 7 (in this embodiment, the limiting protrusion 7 and the central groove shaft 4 are integrally set), and the upper part is a reduced diameter section with a guide ridge 8.

[0064] Working principle: By cooperating with the limiting protrusion 7 and the limiting groove (9 / 10 / 11) inside the cylindrical shell 1, the step-by-step movement of "first straight line and then rotation" is achieved whether it is going up or down; the reduced diameter section cooperates with the guide groove 15 of the inner ring clamping plate 14 through the guide rib 8, which drives the gripper assembly to move.

[0065] Technical function: The core transmission component converts the power of the linear motor into the opening, closing, and rotational motion of the gripper.

[0066] 5. Spiral groove 5

[0067] Installation location: Lower outer surface of the central groove shaft 4.

[0068] Structural relationship: It mates with the pin 6 of the pin sleeve 3, with a circumferential angle of 360°~1080°.

[0069] Working principle: When the pin 6 moves up and down along the spiral groove 5, it forces the central groove shaft 4 to rotate around the axis. The rotation angle is determined by the length of the spiral groove and the lead.

[0070] Technical function: To realize the conversion of linear motion into rotational motion, so that the twisting angle of the fruit stalk meets the requirements for breaking.

[0071] 6. Pin 6

[0072] Installation location: on the side wall of pin sleeve 3, with the inner end extending into the spiral groove 5.

[0073] Structural relationship: It slides with the spiral groove 5 and rises and falls synchronously with the pin sleeve 3.

[0074] Working principle: Through mechanical constraint with the spiral groove 5, the linear motion of the pin sleeve 3 is converted into the rotational torque of the central groove shaft 4.

[0075] Technical function: It connects the pin sleeve and the central groove shaft, transmits rotational power, and is a key contact component for motion conversion.

[0076] 7. Limiting protrusion 7

[0077] Installation location: Two are arranged radially symmetrically in the middle of the central groove shaft 4.

[0078] Structural relationship: Matches the upward limiting groove 9, circumferential limiting groove 10, and downward limiting groove 11 inside the cylindrical shell 1.

[0079] Working principle: When moving within different limiting grooves, the movement direction of the central groove shaft 4 is restricted (only linear movement is allowed within the circumferential limiting groove 10, while rotation is allowed within the upward and downward limiting grooves).

[0080] Technical function: Through mechanical limiting, the "linear-rotation" action is switched to ensure that the gripper completes the opening, closing and twisting in steps.

[0081] 8. Guide ridge 8

[0082] Installation location: three evenly distributed around the circumference of the reduced diameter section of the central groove shaft 4.

[0083] Structural relationship: The top is connected to the hinge seat 12, which is inserted into the guide groove 15 of the inner ring clamping plate 14 in a one-to-one correspondence.

[0084] Working principle: When the central groove shaft 4 rises and falls, it drives the inner ring clamping plate 14 to rotate through the guide groove 15, while constraining the radial displacement of the gripper assembly.

[0085] Technical function: To transmit rotational motion to the gripper assembly, ensuring that the grippers open, close and rotate synchronously, thereby improving motion accuracy.

[0086] 9. Upward limit slot 9

[0087] Installation location: Upper part of the inner wall of the cylindrical shell 1, above the circumferential limiting groove 10.

[0088] Structural relationship: Annular groove, matching the limiting protrusion 7, with the bottom of the groove facing upward.

[0089] Working principle: When the central groove shaft 4 rises to the limit position, the limiting protrusion 7 enters the upper limiting groove 9. At this time, the pin 6 continues to move, which will force the central groove shaft 4 to rotate.

[0090] Technical function: It triggers the rotational action after the grippers open, preparing for the subsequent twisting of the fruit stalk.

[0091] 10. Circumferential limiting groove 10

[0092] Installation location: Upper part of the inner wall of cylindrical shell 1, located between the upper limit groove 9 and the lower limit groove 11.

[0093] Structural relationship: The annular groove matches the limiting protrusion 7 and connects the upper and lower limiting grooves.

[0094] Working principle: When the limiting protrusion 7 is located here, the central groove shaft 4 can only move axially (cannot rotate), ensuring that the gripper can stably complete the opening or closing action.

[0095] Technical function: To achieve separate control of linear motion and rotational motion, avoiding motion interference.

[0096] 11. Downward limit slot 11

[0097] Installation location: Upper part of the inner wall of the cylindrical shell 1, below the circumferential limiting groove 10.

[0098] Structural relationship: Annular groove, matching the limiting protrusion 7, with the bottom of the groove facing downwards.

[0099] Working principle: When the central groove shaft 4 descends to the limit position, the limiting protrusion 7 enters the downward limiting groove 11. At this time, the continued movement of the pin 6 will force the central groove shaft 4 to rotate in the opposite direction.

[0100] Technical function: Triggers the reverse rotation after the grippers close, which, in conjunction with the robotic arm, pulls and twists the fruit stem to break.

[0101] 12. Upper hinge seat 12

[0102] Installation location: Top of guide rib 8, three in total, each corresponding to the hinge plate of the gripper assembly.

[0103] Structural relationship: It is rotatably connected to the hinge plate of the bearing sleeve 22 via a pin.

[0104] Working principle: When the central groove shaft 4 rises and falls, it drives the bearing sleeve 22 to move up and down through the hinge plate, thereby driving the gripper rod 19 to open and close.

[0105] Technical function: Connects the transmission mechanism and the gripper assembly, transmits linear motion to the gripper, and realizes the gripping action.

[0106] 13. Limit bearing 13

[0107] Installation location: Top of cylindrical shell 1.

[0108] Structural relationship: The outer ring is fixed to the cylindrical shell 1, and the inner ring is fixed to the inner ring clamping plate 14.

[0109] Working principle: The outer ring is fixed and the inner ring rotates, allowing the inner ring clamping plate 14 to rotate synchronously with the central groove shaft 4 while maintaining a fixed axial position.

[0110] Technical function: To separate the rotational motion of the gripper assembly from the fixed structure of the cylindrical shell, thereby improving motion stability.

[0111] 14. Inner ring clamp 14

[0112] Installation location: Two limit bearings are installed at intervals on the upper and lower inner rings of bearing 13.

[0113] Structural relationship: It is provided with three guide grooves 15 (which mate with guide ribs 8) and screw holes 16 (which are fixed with bottom ring 17).

[0114] Working principle: The rotational torque of the guide rib 8 is received through the guide groove 15, which drives the bottom ring 17 and the gripper rod 19 to rotate synchronously.

[0115] Technical function: Transmits rotational motion to the gripper assembly; the double-clamp design enhances structural strength and ensures gripping stability.

[0116] 15. Guide groove 15

[0117] Installation location: On the inner ring clamping plate 14, there are three, corresponding one-to-one with the guide ridge 8.

[0118] Structural relationship: The groove shape matches the guide rib 8, and the guide rib 8 is inserted into the groove for sliding fit.

[0119] Working principle: The circumferential displacement of the guide rib 8 is restricted, and the rotational motion of the central groove shaft 4 is transmitted to the inner ring clamping plate 14.

[0120] Technical function: To ensure the synchronization of movement between the transmission mechanism and the gripper assembly, and to avoid jamming caused by radial offset.

[0121] 16. Screw hole 16

[0122] Installation location: On the inner ring clamping plate 14, used for fixed connection with the bottom ring 17.

[0123] Structural relationship: The inner ring clamping plate 14 and the bottom ring 17 are rigidly connected by screws.

[0124] Working principle: The rotational torque of the inner ring clamping plate 14 is transmitted to the bottom ring 17, which in turn drives the gripper rod 19 to rotate.

[0125] Technical function: To ensure a rigid connection between the gripper assembly and the transmission mechanism, preventing loosening or displacement during movement.

[0126] 17. Bottom ring 17

[0127] Installation location: Above the inner ring clamp 14, secured with screws.

[0128] Structural relationship: Three lower hinge seats 18 are evenly distributed in the circumference and are hinged to the gripper rod 19.

[0129] Working principle: It rotates with the inner ring clamping plate 14, and at the same time, the opening and closing angle of the gripper rod 19 is constrained by the lower hinge seat 18.

[0130] Technical function: Connects the inner clamping plate and the gripper bar, transmits rotational motion and provides support for the gripper.

[0131] 18. Lower hinge seat 18

[0132] Installation location: on the bottom ring 17, three in total, corresponding one-to-one with the gripper bar 19.

[0133] Structural relationship: Hinged to the gripper bar 19 via a pin.

[0134] Working principle: As the rotation fulcrum of the gripper bar 19, it works in conjunction with the lifting and lowering motion of the hinge seat 12 to realize the opening and closing of the gripper.

[0135] Technical function: The linkage mechanism that constitutes the gripper converts linear motion into angular displacement of the gripper, thereby enabling the gripping and release of the apple.

[0136] 19. Gripper bar

[0137] Installation position: on the lower hinge seat 18, extending upwards, with the end connected to the clamping groove 20.

[0138] Structural relationship: The middle part is connected to the bearing sleeve 22 via a linear bearing 21, and the top part is hinged to the upper hinge seat 12.

[0139] Working principle: When the bearing sleeve 22 is raised and lowered, the linear bearing 21 pushes the gripper rod 19 to rotate around the lower hinge seat 18 to realize the opening and closing action; when the bottom ring 17 rotates, it drives the clamping groove 20 to twist the fruit stem.

[0140] Technical function: It directly performs clamping and twisting actions and is the core actuator of the gripper assembly.

[0141] 20. Clamping slot 20

[0142] Installation location: Top of gripper bar 19, three grippers, forming a clamping space.

[0143] Structural relationship: The groove shape is adapted to the shape of an apple, and the inner wall may be designed with anti-slip or cushioning structure (not explicitly stated in the document).

[0144] Working principle: When the grippers close, they adhere to the surface of the apple, providing a stable clamping force; when twisted, they drive the fruit stem to rotate through friction.

[0145] Technical function: Directly contacting and grasping apples to ensure no damage to the fruit during harvesting and to enhance the post-harvest commercial value.

[0146] 21. Linear bearing 21 (The document does not include the attached diagram labels; these are added based on the description)

[0147] Installation location: Middle of gripper bar 19.

[0148] Structural relationship: It slides with the bearing sleeve 22 and connects the gripper rod 19 to the bearing sleeve 22.

[0149] Working principle: Reduce friction between bearing sleeve 22 and gripper rod 19 to ensure smooth opening and closing of the gripper.

[0150] Technical function: Reduce friction, improve motion accuracy and reliability, and reduce the risk of jamming.

[0151] 22. Bearing sleeve 22 (The document does not include the attached drawing label; this is added based on the description)

[0152] Installation location: outside of linear bearing 21, connected to upper hinge seat 12 via hinge plate.

[0153] Structural relationship: The enclosure linear bearing 21 rises and falls with the upper hinge seat 12.

[0154] Working principle: It receives the linear motion of the upper hinge seat 12 and drives the gripper rod 19 to rotate and open and close through the linear bearing 21.

[0155] Technical function: To transmit linear motion to the gripper bar, while protecting the linear bearing and improving the durability of the mechanism. Detailed Implementation

[0156] like Figures 1 to 7 As shown, this utility model provides a gripping and rotating coordinated apple picking end effector for installation at the end of a picking robotic arm, including a cylindrical housing 1, a linear motor 2, a transmission mechanism, and a gripper assembly;

[0157] The lower middle part of the transmission mechanism is located inside the cylindrical housing 1, and the top of the transmission mechanism is hinged to the gripper assembly.

[0158] The cylindrical housing 1 is provided with a motion limiting structure that restricts the movement state of the transmission mechanism. The motion limiting structure is used to enable the transmission mechanism to convert the linear motion output by the linear motor 2 into linear motion and rotational motion.

[0159] The gripper assembly opens and then rotates under the upward linear motion output by the transmission mechanism.

[0160] The gripper assembly closes and then rotates in the opposite direction under the downward linear motion output by the transmission mechanism, thereby twisting off the apple stem.

[0161] This invention no longer uses the previous linkage mechanism design, and the number of moving parts is greatly reduced. Through single motor drive and mechanical step-by-step action design, it achieves simplified drive structure, reduced manufacturing cost (reduced number of parts leads to reduced hardware and assembly costs), improved reliability (significantly reduced risk of motion interference) and improved picking efficiency (shortened execution time of compound actions).

[0162] The transmission mechanism includes a pin sleeve 3 and a central groove shaft 4 inserted in the pin sleeve 3. The outer surface of the lower middle part of the central groove shaft 4 is provided with a spiral groove 5. A pin 6 is installed on the side wall of the pin sleeve 3, and the inner end of the pin 6 extends into the spiral groove 5.

[0163] Linear motor 2 is installed at the bottom of cylindrical housing 1. The output end of linear motor 2 is connected to pin sleeve 3 and used to drive pin sleeve 3 to move up and down.

[0164] A limiting protrusion 7 is radially connected to the middle of the central groove shaft 4. The diameter of the central groove shaft 4 above the limiting protrusion 7 is smaller than the diameter of the central groove shaft 4 below it. The central groove shaft 4 above the limiting protrusion 7 is called the reduced diameter section. Two limiting protrusions 7 are symmetrically provided.

[0165] Figure 3 The reason why it appears that there is no reduction in diameter on the right side of the reduced diameter section is because a guide ridge 8 is set there and is precisely cut into it. The guide ridge 8 is integrally set with the reduced diameter section and its outer diameter is the same as the outer diameter of the central groove shaft 4 below the limiting protrusion 7.

[0166] The upper part of the inner wall of the cylindrical shell 1 is radially recessed and provided with an upward limiting groove 9, a circumferential limiting groove 10 and a downward limiting groove 11 that match the limiting protrusion 7. The upward limiting groove 9, the circumferential limiting groove 10 and the downward limiting groove 11 are arranged adjacent to each other from top to bottom. The upward limiting groove 9 and the downward limiting groove 11 are both annular grooves that communicate with the circumferential limiting groove 10. The bottom of the upward limiting groove 9 is on top and the bottom of the downward limiting groove 11 is on the bottom.

[0167] When the central groove shaft 4 is at the lower limit position, the limiting protrusion 7 is located in the downward limiting groove 11;

[0168] When the central groove shaft 4 is at the upper limit position, the limiting protrusion 7 is located in the upper limiting groove 9;

[0169] The motion limiting structure includes the upward limiting groove 9, the circumferential limiting groove 10, and the downward limiting groove 11.

[0170] The transmission mechanism has a simple structure, few parts, and low cost. It can easily convert the linear motion output by the linear motor 2 into sequential linear and rotary motions without the risk of linkage jamming, and the action is accurate and rapid.

[0171] The central groove shaft 4 has three guide ridges 8 on the diameter reduction section limiting protrusion 7. Each guide ridge 8 is evenly distributed in the circumference of the diameter reduction section. Each guide ridge 8 is fixedly connected to an upper hinge seat 12 at its top.

[0172] The gripper assembly includes a limiting bearing 13 mounted on the top of the cylindrical housing 1. The outer ring of the limiting bearing 13 is fixedly connected to the cylindrical housing 1. The inner ring of the cylindrical housing 1 is fixedly connected to an inner ring clamping plate 14 (the inner ring clamping plate 14 is a rotatable part). The inner ring clamping plate 14 is provided with three guide grooves 15. The guide ribs 8 are matched one-to-one with the guide grooves 15, and each guide rib 8 is inserted into the corresponding guide groove 15. Reference numeral 16 is a screw hole on the inner ring clamping plate 14, which is used for fixed connection with the bottom ring 17.

[0173] The inner ring clamping plate 14 is fixedly connected to the bottom ring 17. The bottom ring 17 is provided with three lower hinge seats 18 corresponding to each guide ridge 8. Each lower hinge seat 18 is hinged to a claw rod 19. Each claw rod 19 extends upward and is connected to a clamping groove 20 for clamping apples. Each claw rod 19 is connected to a linear bearing 21. Each linear bearing 21 is connected to a bearing sleeve 22. The bearing sleeve 22 encloses the linear bearing 21. Each bearing sleeve 22 is connected to a hinge plate 23. The hinge plate 23 corresponds to the upper hinge seat 12. The hinge plate 23 is inserted into the corresponding upper hinge seat 12 and rotates with the upper hinge seat 12 through a pin.

[0174] The lower hinge seat 18 corresponds one-to-one with the upper hinge seat 12, and each lower hinge seat 18 forms a concentric outer circle, while each upper hinge seat 12 forms a concentric inner circle. The centers of both the concentric outer and inner circles are located on the axis of the central groove shaft 4.

[0175] The gripper assembly has a simple structure. When the linear bearings 21 and bearing sleeves 22 move upward with the central groove shaft 4, they naturally constrain the gripper bars 19 to open, thus covering the target apple. When the linear bearings 21 and bearing sleeves 22 move downward with the central groove shaft 4, they naturally constrain the gripper bars 19 to retract, thus clamping the target apple. The gripper assembly can rotate together with the central groove shaft 4, thereby realizing the action of twisting the apple.

[0176] Two inner ring clamping plates 14 are provided at intervals. The two inner ring clamping plates 14 improve the structural strength. The circumferential angle of the spiral groove 5 is 360-1080 degrees. The angle of the spiral groove 5 can ensure that the angle of twisting the apple stem reaches 360 degrees to 1080 degrees (including the two ends), ensuring that it can be twisted and broken by the pulling action of the harvesting robot arm.

[0177] This utility model is installed at the end of a harvesting robotic arm as the end effector of the harvesting robot. Its working principle is as follows: a single linear motor 2 drives a composite motion mechanism, converting linear motion into a "clamping and rotating" action of the gripper in stages. Power source: The linear motor 2 provides axial extension and retraction power, driving the pin sleeve 3 to move longitudinally.

[0178] The working process of this utility model is as follows:

[0179] S1. Positioning: The harvesting robot identifies the location of fruits and vegetables through its vision system and drives the robotic arm to align the gripping component of this utility model with the target apple.

[0180] S2. The upward phase of the gripper extending towards the apple: The linear motor 2 drives the pin sleeve 3 to move upward. The limiting protrusion 7 in the middle of the rotating groove shaft immediately enters the circumferential limiting groove 10 from the downward limiting groove 11 on the cylindrical housing 1, thus being restricted from circumferential rotation by the cylindrical housing 1, forcing the rotating groove shaft to only rise axially. When the rotating groove shaft rises axially, it drives the bearing sleeve 22 to rise together through the upper hinge seat 12, forcing each gripper rod 19 and each gripper to open, covering the target apple within it. At the end of the upward phase, the limiting protrusion 7 enters the upward limiting groove 9. After the limiting protrusion 7 enters the upward limiting groove 9, the linear motor 2 drives the pin sleeve 3 to continue moving upward a certain distance. At this time, the rotating groove shaft no longer moves upward. During the process of the pin 6 rising along the spiral groove 5, the pin 6 forces the rotating groove shaft to rotate.

[0181] S3. The descending stage of gripping the apple: The linear motor 2 drives the pin sleeve 3 to move downwards. The limiting protrusion 7 in the middle of the rotating groove shaft immediately enters the circumferential limiting groove 10 from the upper limiting groove 9 on the cylindrical shell 1, thus restricting its circumferential rotation by the cylindrical shell 1 and forcing the rotating groove shaft to descend axially. When the rotating groove shaft descends axially, it drives the bearing sleeve 22 to descend together through the upper hinge seat 12, forcing each gripper rod 19 and each gripper to close, thereby allowing each gripping groove 20 to clamp the target apple. After clamping the apple, the picking robot will control its robotic arm to retract, thus creating a pulling effect on the apple, and most of the apple stems will be broken off.

[0182] S4. Apple Twisting Stage. Linear motor 2 drives pin sleeve 3 to continue moving downwards. The limiting protrusion 7 in the middle of the rotating groove shaft enters the downward limiting groove 11, thus preventing the rotating groove shaft from descending further. At this time, as pin 6 descends along the spiral groove 5, pin 6 forces the rotating groove shaft to rotate in the opposite direction, causing the gripper assembly to rotate together. This twists the stem of the apple that has not been broken. Under the combined action of twisting force and pulling force, the apple stem is effectively broken. For apples whose stems have already been broken in step S2, no torque needs to be applied to the apple in step S3, reducing the load on linear motor 2.

[0183] S5. The picking robot drives the robotic arm to move the gripper assembly to the apple storage position. At this time, the linear motor 2 drives the pin sleeve 3 to move upward, and the gripper assembly opens to release the apple. Then the picking robot drives the robotic arm to move the gripper assembly to the next apple to be picked, so that each gripper of the gripper assembly covers the target apple. Then step S3 can be executed. By repeating steps S3 to S5, apples can be picked continuously.

[0184] This invention can standardize the harvesting process, improve the degree of automation, and the rotational separation method is more suitable for crisp and tender fruit stems than shearing.

[0185] The above embodiments are only used to illustrate and not limit the technical solutions of this utility model. Although the utility model has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the utility model without departing from the spirit and scope of the utility model. Any modifications or partial substitutions should be covered within the scope of the claims of this utility model.

Claims

1. A gripping and rotating coordinated apple-picking end effector, for installation at the end of a picking robotic arm, characterized in that: Includes a cylindrical housing, a linear motor, a transmission mechanism, and a gripper assembly; The lower middle part of the transmission mechanism is located inside the cylindrical housing, and the top of the transmission mechanism is hinged to the gripper assembly. The cylindrical housing is equipped with a motion limiting structure that restricts the movement of the transmission mechanism. The motion limiting structure is used to enable the transmission mechanism to convert the linear motion output by the linear motor into linear motion and rotational motion. The gripper assembly opens and then rotates under the upward linear motion output by the transmission mechanism. The gripper assembly closes and then rotates in the opposite direction under the downward linear motion output by the transmission mechanism, thereby twisting off the apple stem. The transmission mechanism includes a pin sleeve and a central groove shaft inserted in the pin sleeve. The outer surface of the lower middle part of the central groove shaft is provided with a spiral groove. A pin is installed on the side wall of the pin sleeve, and the inner end of the pin extends into the spiral groove. A linear motor is installed at the bottom of the cylindrical housing. The output end of the linear motor is connected to the pin sleeve and is used to drive the pin sleeve to move up and down. A limiting protrusion is radially connected to the middle of the central groove shaft. The diameter of the central groove shaft above the limiting protrusion is smaller than the diameter of the central groove shaft below it. The central groove shaft above the limiting protrusion is called the reduced diameter section. The upper part of the inner wall of the cylindrical shell is radially recessed and provided with an upward limiting groove, a circumferential limiting groove and a downward limiting groove that match the limiting protrusion. The upward limiting groove, the circumferential limiting groove and the downward limiting groove are arranged adjacent to each other from top to bottom. When the central groove shaft is at the lower limit position, the limiting protrusion is located in the downward limiting groove; When the central groove shaft is at its upper limit position, the limiting protrusion is located within the upper limiting groove; The motion limiting structure includes the upward limiting groove, the circumferential limiting groove, and the downward limiting groove.

2. The grasping and rotating coordinated apple picking end effector according to claim 1, characterized in that: The central groove shaft has three guide ridges on the diameter reduction section limiting protrusion. Each guide ridge is evenly distributed around the diameter reduction section. Each guide ridge is fixedly connected to an upper hinge seat at its top. The gripper assembly includes a limit bearing installed at the top of the cylindrical housing. The outer ring of the limit bearing is fixedly connected to the cylindrical housing. An inner ring clamping plate is fixedly connected to the inner ring of the cylindrical housing. The inner ring clamping plate is provided with three guide grooves. The guide ridges and guide grooves are matched one by one, and each guide ridge is inserted into the corresponding guide groove. The inner ring clamp is fixedly connected to the bottom ring. The bottom ring is provided with three lower hinge seats corresponding to each guide ridge. Each lower hinge seat is hinged to a gripper rod. Each gripper rod extends upward and is connected to a gripping groove for gripping apples. Each gripper rod is connected to a linear bearing. Each linear bearing is connected to a bearing sleeve. The bearing sleeve encloses the linear bearing. Each bearing sleeve is connected to a hinge plate. The hinge plate corresponds to the upper hinge seat. The hinge plate is inserted into the corresponding upper hinge seat and rotates with the upper hinge seat through a pin. The lower hinge seats correspond one-to-one with the upper hinge seats, and each lower hinge seat forms a concentric outer circle, while each upper hinge seat forms a concentric inner circle. The centers of both the concentric outer and inner circles are located on the axis of the central groove shaft.

3. The grasping and rotating coordinated apple picking end effector according to claim 2, characterized in that: The inner ring clamp is provided with two plates spaced apart at the top and bottom.

4. The grasping and rotating coordinated apple picking end effector according to claim 2, characterized in that: The circumferential angle of the spiral groove is 360-1080 degrees.

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