Tomato picking, shearing and clamping integrated end effector with force sensing function

Abstract

The invention provides a tomato stem shearing and clamping integrated end effector with a force sensing function. The tomato stem shearing and clamping integrated end effector comprises a supporting frame; the servo electric push rod is mounted on the support frame; the shearing mechanism comprises an upper shear blade and a lower shear blade which are oppositely positioned, the lower shear blade is fixed on the support frame, and the upper shear blade is connected with the servo electric push rod; the torsion clamping mechanism is arranged below the shearing mechanism, and is used for clamping the sheared fruit stem section when the fruit stem is sheared; and the piezoelectric film force sensing mechanism is fixed on the torsion clamping mechanism and is used for sensing the change of the clamping force in real time and transmitting an electric signal to a control system through a signal processing module so as to dynamically adjust the clamping force. The end effector clamps the cut-off fruit stems while cutting off the tomato fruit stems, so that fruits are not directly touched and extruded, and real nondestructive picking is realized.

Description

Technical Field

[0001] This invention relates to the field of agricultural machinery and intelligent equipment technology, and in particular to an end effector for tomato harvesting, especially an integrated end effector for cutting and clamping tomato stems with force sensing function. Background Technology

[0002] With the development of agricultural modernization and intelligentization, the application of robotics technology in agricultural production is becoming increasingly widespread. As a high-value economic crop, tomatoes require not only high efficiency and low cost in their harvesting process, but also the preservation of fruit quality.

[0003] Traditional manual harvesting suffers from high labor intensity, low efficiency, and easy damage to the fruit. Existing harvesting robots primarily employ two types of end effectors: one uses flexible grippers to directly hold the fruit, with the robotic arm twisting to break the stem; the other is a combined gripper-shear structure, where the flexible grippers hold the fruit while the scissors cut the stem, though these actions are separate. However, both methods lack precise control and sensing capabilities, often resulting in fruit compression or inaccurate cutting, increasing fruit damage and the risk of fruit falling, thus affecting fruit quality. These end effectors have many shortcomings in practical applications. For example, pure gripping mechanisms easily pull on the stem during harvesting, causing plant damage or fruit drop; the combined gripper-shear structure, due to its complex structure, large size, and high control difficulty, cannot effectively locate the stem, increasing the risk of fruit drop and damage, thus hindering its widespread application in actual production. Summary of the Invention

[0004] To address the shortcomings of the existing technologies, this invention provides an integrated end effector for cutting and holding tomato stems with force sensing function. This solves the problems of low harvesting efficiency, high fruit damage rate, and complex structure in the existing technologies. The end effector cuts the tomato stems while holding the cut stems, preventing the fruit from being directly touched or squeezed, thus achieving truly damage-free harvesting.

[0005] To achieve the above objectives, the present invention provides an integrated end effector for cutting and holding tomato stems with force sensing function, comprising:

[0006] Support frame;

[0007] A servo electric actuator is mounted on the support frame;

[0008] A shearing mechanism, comprising an upper shear blade and a lower shear blade positioned relative to each other, the lower shear blade being fixed on the support frame, and the upper shear blade being connected to the servo electric actuator;

[0009] A torque clamping mechanism is provided below the shearing mechanism and is used to clamp the cut-off fruit stem segment when shearing the fruit stem.

[0010] The piezoelectric film force sensing mechanism is fixed on the torque clamping mechanism and is used to sense changes in clamping force in real time and transmit electrical signals to the control system through the signal processing module to dynamically adjust the clamping force.

[0011] In some embodiments, the servo electric actuator is connected to a actuator motor, the actuator motor is mounted on an actuator motor support, and a servo electric actuator shaft is also mounted on the actuator motor via a first locking nut.

[0012] In some embodiments, the servo electric actuator is connected to the upper scissor blade via a connecting shaft and an actuator shaft.

[0013] In some embodiments, the torque clamping mechanism includes:

[0014] A movable clamping block and a fixed clamping block are provided, wherein the movable clamping block is installed below the upper scissor blade, and the fixed clamping block is installed below the lower scissor blade.

[0015] The movable clamping block and the fixed clamping block are connected to the push rod motor via the upper scissor blade and the lower scissor blade.

[0016] In some embodiments, the torque clamping mechanism further includes: a torsion spring, a clamping shaft, and a positioning screw;

[0017] The movable clamping block can rotate around the clamping shaft. The center ring of the torsion spring is nested on the clamping shaft. One end of the spring is restricted from moving by the positioning screw, and the other end is connected to the hole in the movable clamping block.

[0018] In some embodiments, the piezoelectric film force sensing mechanism includes: a piezoelectric film and a control module connected thereto. The piezoelectric film is embedded inside the movable clamping block near the fruit stem clamping area. The piezoelectric film senses changes in clamping force in real time, and the distance between the movable clamping block and the fixed clamping block is controlled by the stroke of the servo electric actuator.

[0019] In some embodiments, the control module is further provided with a control module housing on the outside, and a top cover is installed on the support frame by Phillips screws.

[0020] In some embodiments, the upper scissor blade and the lower scissor blade are connected together by a rotating shaft and a second locking nut.

[0021] In some embodiments, the servo electric actuator includes a built-in high-strength worm gear transmission mechanism, a high-precision encoder, and a high-performance servo control system.

[0022] In some embodiments, the support frame is made of high-strength aluminum alloy and has multiple mounting slots.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] The tomato stem cutting and clamping integrated end effector with force sensing function provided by this invention can accurately cut the stem during the harvesting process, achieving precise cutting and synchronous clamping of the tomato stem. It can also stably clamp the stem without directly touching the fruit at the moment of cutting. This device can minimize mechanical contact and pressure on the fruit, prevent fruit damage and falling, and thus achieve efficient and damage-free tomato harvesting.

[0025] The end effector provided by this invention is a reciprocating structure driven by a micro servo electric actuator. Through precise control of the servo electric actuator, piezoelectric film clamping force sensing, and torsional elastic clamping, it achieves precise cutting of tomato stems and stable clamping of the fruit, effectively preventing fruit drop and damage during harvesting. The application of the servo electric actuator improves the equipment's response speed and control accuracy, the introduction of the piezoelectric film enhances the intelligent adjustment capability of the clamping force, and the torsional elastic clamping mechanism ensures clamping while cutting the stems. The overall structure is compact, low-cost, and easy to maintain, making it suitable for large-scale application in automated tomato harvesting equipment, greatly improving harvesting efficiency and reducing fruit damage.

[0026] The tomato stem shearing and clamping integrated end effector with force sensing function provided by this invention also has good scalability. The parameters of the shearing mechanism and clamping mechanism can be adjusted according to the harvesting needs of different crops to adapt to various harvesting environments. Through modular design, the compatibility between the components is strong, which facilitates customized improvement according to actual application conditions, further enhancing the versatility and adaptability of the equipment. The combination of the servo electric actuator control system, the piezoelectric film force sensing system and the torque elastic clamping mechanism enables the end effector provided by this invention to maintain a highly efficient and stable working state under different harvesting conditions, meeting diverse harvesting needs.

[0027] In practical applications, the tomato harvesting, shearing, and clamping integrated end effector with sensing function provided by this invention can be seamlessly integrated with various types of harvesting robots or robotic arms, providing a stable and efficient harvesting solution. Its intelligent control system and precise mechanical structure ensure that high-precision harvesting results can still be maintained under high-speed operation. Through the efficient drive of the servo electric actuator system, the intelligent force sensing of the piezoelectric film, and the flexible clamping of the torsional elastic clamping mechanism, the technical solution of this invention significantly improves the overall performance of the tomato harvesting robot, reduces labor costs and labor intensity, and meets the market demand for high-quality fruits. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the overall structure of the integrated end effector for tomato harvesting, shearing, and clamping with force sensing function, as shown in an embodiment of the present invention.

[0029] Figure 2 is a partial cross-sectional view of the tomato picking, cutting, and clamping integrated end effector with force sensing function shown in an embodiment of the present invention (through which the internal servo electric actuator and control module can be seen).

[0030] Figure 3 is a schematic diagram of the servo electric actuator mounting structure shown in an embodiment of the present invention;

[0031] Figure 4 is a schematic diagram of the torsion elastic clamping mechanism shown in an embodiment of the present invention;

[0032] In the attached figures, the following labels are used:

[0033] 1-Support frame;

[0034] 2-Servo electric actuator;

[0035] 3-Use the scissor blades;

[0036] 4- Cut the blades down;

[0037] 5- Rotating shaft;

[0038] 6-Second locking nut;

[0039] 7-Push rod motor;

[0040] 701 - First locking nut;

[0041] 702-Servo Electric Actuator Shaft;

[0042] 8-Push rod motor support;

[0043] 9-Connecting shaft;

[0044] 10 - Push rod pivot;

[0045] 11-Moving clamping block;

[0046] 12-Fixed clamping block;

[0047] 13-Torsion spring;

[0048] 14-Clamp the shaft;

[0049] 15 - Locating screws;

[0050] 16-Piezoelectric thin film;

[0051] 17-Control Module;

[0052] 18 - Control module housing;

[0053] 19-Phillips head screw;

[0054] 20 - Top cover. Detailed Implementation

[0055] See Figure 1-4 An embodiment of the present invention provides an integrated end effector for cutting and clamping tomato stems with force sensing function, comprising: a support frame 1; a servo electric actuator 2, mounted on the support frame 1 via a pin and a bracket; a cutting mechanism, the cutting mechanism including an upper shear blade 3 and a lower shear blade 4 positioned relative to each other, the lower shear blade 4 being fixed on the support frame 1, and the upper shear blade 3 being connected to the telescopic rod of the servo electric actuator 2 via an adapter module; the upper shear blade 3 and the lower shear blade 4 being connected together via a rotating shaft 5 and a second locking nut 6, the two being positioned relative to each other to form a cutting pair, achieving precise cutting of the tomato fruit; the upper shear blade 3 reciprocating under the drive of the servo electric actuator 2 to cut the tomato stem; a torque clamping mechanism, the torque clamping mechanism being located below the cutting mechanism, used to clamp the cut stem segment during stem cutting; and a piezoelectric film force sensing mechanism, fixed on the torque clamping mechanism, used to sense changes in clamping force in real time and transmit electrical signals to the control system via a signal processing module to dynamically adjust the clamping force.

[0056] In this embodiment, the servo electric actuator 2 is connected to a actuator motor 7, which is mounted on an actuator motor support 8. A servo electric actuator shaft 702 is also mounted on the actuator motor 7 via a first locking nut 701. The servo electric actuator 2 is connected to the upper shear blade 3 via a connecting shaft 9 and an actuator shaft 10, forming a reciprocating shearing mechanism.

[0057] The torque clamping mechanism described in this embodiment includes a movable clamping block 11 and a fixed clamping block 12. The movable clamping block 11 is installed below the upper scissor blade 3, and the fixed clamping block 12 is installed below the lower scissor blade 4. The movable clamping block 11 and the fixed clamping block 12 are connected to the push rod motor 7 through the upper scissor blade 3 and the lower scissor blade 4. The movable clamping block and the fixed clamping block close synchronously when cutting the fruit stem to clamp the cut fruit stem segment. The material and shape of the movable clamping block 11 and the fixed clamping block 12 (i.e., clamping blocks) can be changed according to the shape of the fruit stem to avoid damage to the fruit and improve clamping stability.

[0058] The torque clamping mechanism in this embodiment further includes: a torsion spring 13, a clamping shaft 14, and a positioning screw 15; the movable clamping block 11 can rotate around the clamping shaft 14, and the central coil of the torsion spring 13 is nested on the clamping shaft 14, with one end restricted by the positioning screw 15 and the other end connected to a hole in the movable clamping block 11. In this embodiment, the movable clamping block 11 is installed below the upper scissor blade 3 via the torsion spring 13 and can rotate around the clamping shaft 14. The torsion spring 13 provides elastic clamping force to ensure that the movable clamping block 11 and the fixed clamping block 12 firmly clamp the fruit stem during cutting.

[0059] When the servo electric actuator 2 pushes out and drives the shearing mechanism to operate, the moving clamp 11 and the fixed clamp 12 close under the drive of the shearing mechanism. Before shearing the fruit stem, the moving clamp 11 and the fixed clamp 12 contact the fruit stem. While the fruit stem continues to be sheared and squeezed, the moving clamp 11 rotates around the clamping shaft 14. At the same time, under the pull of the torsion spring 13, the moving clamp 11 and the fixed clamp 12 maintain a certain clamping force with the fruit stem to prevent it from falling off.

[0060] The piezoelectric film force sensing mechanism described in this embodiment includes a piezoelectric film 16 and a control module 17 connected thereto. The piezoelectric film 16 is embedded inside the movable clamping block 11 near the fruit stem clamping area and in contact with the fruit stem. The piezoelectric film 16 senses changes in clamping force in real time, and the distance between the movable clamping block 11 and the fixed clamping block 12 is controlled by the stroke of the servo electric push rod 2, thereby controlling the clamping force on the fruit stem after shearing. This integrated clamping and shearing end-effector structure effectively reduces pressure on the fruit skin and lowers the risk of damage.

[0061] In this embodiment, the piezoelectric film force sensing mechanism includes a piezoelectric film 16 embedded in the moving clamping block 11 and the fixed clamping block 12, and a control module 17 connected to the piezoelectric film 16. The control module 17 dynamically adjusts the stroke of the servo electric actuator 2 according to the electrical signal generated by the piezoelectric film 16 to achieve adaptive clamping. The piezoelectric film force sensing module has a fault detection and feedback mechanism. When an abnormal force change is detected during the clamping process, the control system automatically adjusts the control parameters to ensure the stability and safety of the clamping process.

[0062] In this embodiment, a control module housing 18 is also provided on the outside of the control module 17, and a top cover 20 is installed on the support frame 1 by a cross screw 19.

[0063] In this embodiment, the servo electric actuator 2 includes a built-in high-strength worm gear transmission mechanism, a high-precision encoder, and a high-performance servo control system. The servo electric actuator achieves precise control of motion speed and stroke through programming, and realizes motion limit through built-in limit switches to adapt to fruit stems of different thicknesses.

[0064] Specifically, the push rod motor provided in this embodiment adopts a micro servo electric cylinder control system, which can achieve precise control of stroke and speed through programming. The control module is connected to the piezoelectric film through the signal processing module. During the clamping process, the piezoelectric film senses the magnitude of the fruit stem clamping force in real time and feeds it back to the controller module. The control system adjusts the stroke of the push rod in real time according to the set clamping pressure value, realizing real-time monitoring and dynamic adjustment of the clamping force, ensuring that the best clamping effect can be maintained in various picking environments and fruit conditions.

[0065] The support frame described in this embodiment is made of high-strength aluminum alloy and has multiple mounting slots to accommodate different types of harvesting robots or robotic arms. Its compact design reduces vibration and noise, facilitating quick installation and disassembly on various harvesting robots or robotic arms. The material properties of the support frame ensure its durability in high-temperature and humid environments, making it suitable for greenhouse and outdoor operations. The compact design of the support frame optimizes the internal space layout, effectively reducing equipment vibration and noise, and improving the overall stability and durability of the actuator.

[0066] The end effector provided in this embodiment supports parameter adjustment through modular design. The parameters of the shearing mechanism and the clamping mechanism can be customized and improved according to the harvesting needs of different crops. The end effector is integrated with the harvesting robot or robotic arm through a standardized interface, supports quick installation and disassembly, and is suitable for greenhouse and outdoor operating environments.

[0067] In this embodiment, through the lightweight and miniaturized innovative structural design of the servo electric actuator, shearing mechanism, and force-sensing elastic clamping mechanism, precise cutting and stable clamping of tomato stems are achieved, making it suitable for automated tomato harvesting operations. Simultaneously with the cutting of the stem, the clamping block closes and holds the cut stem segment, preventing the stem and attached fruit from falling due to gravity.

[0068] The servo electric actuator provided in this embodiment adopts a built-in high-strength worm gear transmission mechanism, a high-precision encoder, and a high-performance servo control system, which has the advantages of large thrust, high precision, and high speed. The shearing mechanism consists of upper and lower shear blades, which are axially positioned relative to each other through a rotating shaft and a positioning nut. Their movement trajectory is flexible and controllable. The lower shear blade is fixed on the support frame and works with the upper shear blade to form a robust shearing pair. When the upper shear blade is closed, it can quickly and cleanly cut the tomato stem, creating the basic conditions for non-destructive harvesting. The torque clamping mechanism mainly consists of a pair of clamping blocks, a torsion spring, and screws, among other standard parts. A relatively stationary passive clamping block is fixedly installed below the lower shear blade, and a moving clamping block is installed below the upper shear blade through the action of the torsion spring. When the shearing mechanism performs shearing, the moving clamping block rotates and approaches the passive clamping block, the shear blades perform the shearing action, and the lower moving clamping block twists after contacting the stem, and the torsion spring acts to provide elastic clamping. This design applies sufficient clamping force to the cut fruit stem while avoiding excessive compression, ensuring a stable grip on the stem without directly contacting the fruit surface. A piezoelectric film force sensing module is fixed to the clamping block of the torque clamping mechanism, positioned at the point of contact with the stem, allowing for real-time sensing of changes in clamping force. The electrical signal generated by the piezoelectric film is transmitted to the control system via a signal processing module, which dynamically adjusts the clamping force accordingly, achieving adaptive clamping. The clamping block simultaneously closes to firmly hold the cut stem as the upper shear blades sever it. This design not only prevents fruit drop due to vibration or gravity but also ensures the fruit is not compressed or rubbed during harvesting, achieving truly damage-free harvesting. Furthermore, the piezoelectric film features a fault detection and feedback mechanism. When abnormal force changes occur during clamping, the system automatically adjusts the corresponding control parameters to ensure the stability and safety of the clamping process. This flexible and precise control method significantly improves the reliability and adaptability of the clamping mechanism.

[0069] In summary, the tomato stem shearing and clamping integrated end effector with force sensing function provided by this invention achieves precise shearing and synchronous clamping of tomato stems through the coordinated design of the push rod motor and the shearing and clamping mechanism, preventing the fruit from falling during harvesting. The torsional elastic clamping mechanism cleverly converts the torsional force of the torsion spring into a stem clamping force, achieving elastic clamping of the stem. The introduction of the piezoelectric film enhances the intelligent control capability of the clamping force, enabling dynamic adjustment of the clamping force according to the actual clamping force, ensuring the stability and safety of the clamping process. The overall structure is compact, easy to maintain, and suitable for large-scale applications, helping to improve the working efficiency of automated tomato harvesting equipment and reduce fruit damage.

[0070] Furthermore, the end effector provided by this invention can adjust the parameters of the cutting and clamping mechanisms according to the harvesting needs of different crops. For example, for thicker fruit stalks, the stroke length of the push rod motor and the clamping force of the moving clamp can be adjusted to achieve precise cutting and stable clamping of larger diameter fruit stalks. For fruit stalks of different shapes, replacing the moving and fixed clamps with different materials and shapes can also effectively prevent damage to the fruit.

[0071] In practical applications, the end effector of this invention can be seamlessly integrated with various types of harvesting robots or robotic arms. Through standardized interface design and modular component structure, users can quickly configure and adjust the equipment according to specific harvesting needs and operating environments. For example, under high-speed operating conditions, the high response speed and high control precision of the push rod motor ensure continuous and rapid shearing and clamping actions, meeting the needs of large-scale harvesting operations. Simultaneously, the real-time force sensing function of the piezoelectric film effectively prevents fruit damage caused by over-clamping or unstable clamping, improving the overall quality and efficiency of harvesting operations.

[0072] This invention combines servo electric actuator drive, piezoelectric film force sensing, and torque elastic clamping technology, significantly improving harvesting accuracy and efficiency. The servo electric actuator employs advanced real-time control technology, allowing for precise control of its speed and stroke through programming, adapting to different fruit stem thicknesses and cutting requirements. The system boasts fast response and high control precision, ensuring rapid and accurate execution of each cutting and clamping action. Built-in limit switches limit the movement, improving overall energy efficiency. The piezoelectric film on the clamping block connects to the control module, enabling real-time monitoring and feedback of the clamping force. Based on the electrical signals provided by the piezoelectric film, the control module dynamically adjusts the clamping force, ensuring optimal clamping performance under various harvesting environments and fruit conditions, enhancing clamping accuracy and safety, and providing a solid foundation for intelligent harvesting.

Claims

1. A force-sensing tomato stem cutting and gripping integrated end effector, characterized in that: The application relates to a fruit stem cutting device. The device comprises a support frame, a servo electric push rod installed on the support frame, a shearing mechanism comprising upper and lower shearing blades arranged oppositely, the lower shearing blade being fixed on the support frame, the upper shearing blade being connected with the servo electric push rod, a torsion clamping mechanism arranged below the shearing mechanism and used for clamping the cut fruit stem segment when the fruit stem is cut, and a piezoelectric film force sensing mechanism fixed on the torsion clamping mechanism and used for sensing the change of the clamping force in real time and transmitting the electric signal to a control system through a signal processing module to dynamically adjust the clamping force. The servo electric push rod is connected with a push rod motor, the push rod motor is installed on a push rod motor support, and a servo electric push rod rotating shaft is further installed on the push rod motor through a first locking nut. The servo electric push rod is connected with the upper shearing blade through a connecting shaft and a push rod rotating shaft. The torsion clamping mechanism comprises a movable clamping block and a fixed clamping block, the movable clamping block is installed below the upper shearing blade, and the fixed clamping block is installed below the lower shearing blade. The movable clamping block and the fixed clamping block are connected with the push rod motor through the upper shearing blade and the lower shearing blade.

2. The force sensing tomato stem cutting and gripping integrated end effector according to claim 1, wherein: The torsion clamping mechanism further comprises a torsion spring, a clamping rotating shaft and a positioning screw.

3. The force sensing tomato stem cutting and gripping integrated end effector according to claim 2, wherein: The movable clamping block can rotate around the clamping rotating shaft, the center ring of the torsion spring is nested on the clamping rotating shaft, one end of the center ring is limited in movement by the positioning screw, and the other end is connected with a hole in the movable clamping block.

4. The force sensing tomato stem cutting and gripping integrated end effector according to claim 2, wherein: The piezoelectric film force sensing mechanism comprises a piezoelectric film and a control module connected with the piezoelectric film, the piezoelectric film is embedded in the movable clamping block near the fruit stem clamping position, the change of the clamping force is sensed in real time through the piezoelectric film, and the distance between the movable clamping block and the fixed clamping block is controlled through the stroke of the servo electric push rod. A control module shell is further arranged outside the control module, and an upper cover is installed on the support frame through cross screws. The upper shearing blade and the lower shearing blade are connected through a rotating shaft and a second locking nut.

5. The force sensing tomato stem cutting and gripping integrated end effector according to claim 4, wherein: The servo electric push rod comprises a built-in high-strength worm gear transmission mechanism, a high-precision encoder and a high-performance servo control system. The support frame is made of high-strength aluminum alloy and has multiple installation spaces.

6. The force sensing tomato stem cutting and gripping integrated end effector according to claim 4, wherein: ​ 7. The force sensing tomato peduncle shearing and gripping integrated end effector according to claim 6, characterized in that: ​ 8. The force sensing tomato stem cutting and gripping integrated end effector according to claim 1, wherein: ​ 9. The force sensing tomato stem cutting and gripping integrated end effector according to claim 1, wherein: ​ 10. The force sensing tomato stem cutting and gripping integrated end effector according to claim 1, wherein: ​

Images