Bistable flexible vibration absorption gripper for fruits and vegetables with large length-diameter ratio

Abstract

The invention discloses a bistable flexible vibration absorption gripper for fruits and vegetables with large length-diameter ratio, which comprises a fixed plate, a size adjusting device and a plurality of flexible gripping mechanisms uniformly distributed along the circumferential direction, and the size adjusting device is arranged on the fixed plate and is used for driving the plurality of flexible gripping mechanisms to synchronously change the radial position so as to adjust the gripping space. Each flexible grabbing mechanism comprises a mounting base, a linear driving source and a flexible clamping bag body, the mounting bases are connected with the size adjusting devices and move in the radial direction under driving of the size adjusting devices, bistable elastic pieces are arranged in the flexible clamping bag bodies, the bistable elastic pieces have a first stable state and a second stable state, and the first stable state and the second stable state are parallel to each other. The bistable elastic sheet is in a straightened state in the first stable state, and the bistable elastic sheet is in an inward bending state in the second stable state; the fruit and vegetable grabbing device has the advantages that fruits and vegetables of different sizes can be rapidly, stably and losslessly grabbed, and the working efficiency and grabbing adaptability are improved.

Description

Technical Field

[0001] This invention relates to the field of agricultural machinery, and in particular to a bistable flexible vibration-absorbing gripper for fruits and vegetables with large aspect ratios. Background Technology

[0002] With the increasing intelligence and automation of modern agricultural production, the reliance on mechanized equipment in fruit and vegetable harvesting, sorting, and packaging is growing. Fruit and vegetable gripping devices, as key components in automated fruit and vegetable production lines, are responsible for directly contacting and handling fruits and vegetables, and their performance directly affects processing efficiency and product integrity. Especially when dealing with diverse fruit and vegetable varieties and significant morphological differences, flexible fruit and vegetable grippers capable of efficient and damage-free gripping are of great significance for improving the automation level of post-harvest processing, reducing labor costs, and minimizing fruit and vegetable damage.

[0003] Currently, common fruit and vegetable gripping devices are mainly divided into two categories: rigid mechanical claws and flexible pneumatic grippers. Rigid mechanical claws have high structural strength and good control precision, but due to their hard contact surface, they are prone to causing scratches or indentations on the skin when gripping fruits and vegetables, making them particularly unsuitable for soft or thin-skinned fruits and vegetables. Flexible grippers are usually made of elastomer materials such as silicone and rubber, and achieve a wrap-around gripping effect through air pressure, which can reduce the damage rate to some extent. However, traditional flexible grippers still have significant shortcomings in terms of response speed, gripping stability, and size adaptability. For example, when fruits and vegetables vary greatly in size or are long and thin (such as cucumbers, loofahs, and honeydew melons), the flexible fingers cannot form a stable covering contact. This is because the deformation range of the flexible pneumatic material is limited, and it cannot provide sufficient support and friction in the length direction, resulting in uneven distribution of clamping force. At the same time, long and thin fruits and vegetables are prone to swaying due to gravity or inertia during the grasping process, and the response lag of the flexible material makes it difficult for the gripper to compensate for changes in posture in time, resulting in slippage, deflection, or local collapse, which affects the grasping stability and operation accuracy.

[0004] In summary, existing flexible fruit and vegetable grippers still suffer from problems such as slow structural response, unstable gripping, and insufficient impact resistance when adapting to fruits and vegetables of different sizes and shapes, making it difficult to simultaneously meet the requirements of high responsiveness and safe gripping. Therefore, there is an urgent need to develop a flexible gripping device with adjustable structure, sensitive response, and vibration absorption and buffering capabilities to improve gripping efficiency and adaptability while ensuring the integrity of the fruit and vegetable surface, thereby promoting the intelligent and non-destructive development of post-harvest processing of fruits and vegetables. Summary of the Invention

[0005] The purpose of this invention is to provide a bistable flexible vibration-absorbing gripper for fruits and vegetables with large aspect ratios, which can achieve rapid, stable and non-destructive gripping of fruits and vegetables of different sizes, thereby improving work efficiency and gripping adaptability.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a bistable flexible vibration-absorbing gripper for fruits and vegetables with large aspect ratios, comprising a fixed plate, a size adjustment device, and multiple flexible gripping mechanisms evenly distributed along the circumferential direction. The size adjustment device is disposed on the fixed plate and is used to drive the multiple flexible gripping mechanisms to synchronously change their radial positions to adjust the gripping space. Each flexible gripping mechanism includes a mounting base, a linear drive source, and a flexible clamping capsule. The mounting base is connected to the size adjustment device and moves radially under the drive of the size adjustment device. A bistable elastic sheet is disposed in the flexible clamping capsule. The bistable elastic sheet has a first stable state and a second stable state. In the first stable state, the bistable elastic sheet is in a straight state, and in the second stable state, the bistable elastic sheet is in an inwardly bent state. The linear drive source is disposed on the mounting base and is used to apply force to the bistable elastic sheet, driving it to switch between the first stable state and the second stable state, thereby driving the flexible clamping capsule to switch between the straightened state and the bent state to achieve the clamping and release of fruits and vegetables.

[0007] Preferably, the size adjustment device includes a drive cylinder, a transmission component, and a guide component. The transmission component is connected to the output end of the drive cylinder. The guide component is fixed below the fixed plate and has a through hole in its center. Each mounting seat is connected to the guide component via a sliding guide mechanism and to the transmission component via a motion conversion mechanism. The axial movement of the transmission component is converted into the radial movement of the mounting seat via the motion conversion mechanism.

[0008] Preferably, the motion conversion mechanism includes a connecting frame and a vibration-absorbing connecting assembly. The connecting frame is fixedly connected to the transmission component, and the vibration-absorbing connecting assembly is connected between the connecting frame and the mounting base. The vibration-absorbing connecting assembly is provided with a sliding member, and the outer side of the mounting base is provided with a first inclined slide rail that slopes outward from top to bottom. The sliding member slides in cooperation with the first inclined slide rail. When the drive source drives the transmission component and the connecting frame to move axially, the vibration-absorbing connecting assembly moves axially synchronously with the connecting frame, and the sliding member slides along the first inclined slide rail, pushing the mounting base to move radially.

[0009] Preferably, the vibration-absorbing connection assembly includes an elastic plate and a fixing block. One end of the elastic plate is fixed to the lower end of the connecting frame, the fixing block is fixed to the other end of the elastic plate, and the sliding member is rotatably connected inside the fixing block.

[0010] Preferably, the upper end of the connecting frame is fixed with symmetrically distributed guide rods, and the fixing plate is provided with symmetrically distributed linear bearings, with the guide rods slidingly engaging with the corresponding linear bearings.

[0011] Preferably, the sidewall of the transmission component is uniformly provided with multiple second inclined slides that slope outwards from top to bottom. The number of second inclined slides is the same as the number of flexible gripping mechanisms. The sliding guide mechanism includes a mounting column, a mounting block, and a slide bearing. The mounting column is fixed to the upper end of the mounting base, the mounting block is fixed to the upper end of the mounting column, and the slide bearing is rotatably connected inside the mounting block and cooperates with the corresponding second inclined slide. Two movable bearings are also symmetrically arranged at the lower part of the mounting column. The two movable bearings roll into contact with the radial slides provided on the guide component to guide the radial movement of the mounting base.

[0012] Preferably, the linear drive source includes a flexible airbag and a limiting member. The flexible airbag is disposed on the mounting base, and one end of the flexible airbag is connected to the flexible clamping bladder. The limiting member is wound around the outer wall of the flexible airbag to limit the radial expansion of the flexible airbag and guide its axial elongation. When the flexible airbag is inflated, it expands radially and elongates axially, driving the bistable elastic sheet to quickly switch from a first stable state to a second stable state. When the flexible airbag is deflated, it shortens axially, and the bistable elastic sheet resets from the second stable state to the first stable state under the action of elastic restoring force, causing the flexible clamping bladder to return to its straightened state.

[0013] Preferably, the limiting member includes multiple winding threads, which are wound around the outer wall of the flexible airbag at a 45° helix angle in both clockwise and counterclockwise directions, to prevent the flexible airbag from rupturing due to excessive radial deformation, and to enable the flexible airbag to undergo simultaneous radial expansion and axial elongation deformation when inflated.

[0014] Preferably, the flexible clamping capsule includes a flexible capsule body, the bistable elastic sheet is fixed in the flexible capsule body, and the flexible capsule body is divided into a driving chamber and a sealing chamber. The driving chamber is located on one side close to the linear driving source, and the sealing chamber is located on the other side and is sealed. The sealing chamber is filled with gas.

[0015] Preferably, both the flexible airbag and the flexible clamping bladder are made of thermoplastic elastomer material with a Shore hardness of 90A through 3D printing.

[0016] Compared with existing technologies, the advantages of this invention are as follows: This device achieves efficient and non-destructive gripping of fruits and vegetables with large aspect ratios through a bistable drive mechanism and a size adaptive adjustment system. The size adjustment device can drive multiple flexible gripping mechanisms to move synchronously radially according to the diameter of the fruits and vegetables, adjusting the gripping space to accommodate fruits and vegetables of different sizes, thus solving the problem of poor size adaptability of traditional flexible grippers. During the gripping process, the linear drive source applies a thrust to the bistable elastic sheet inside the flexible gripping capsule. Utilizing the characteristic of the bistable elastic sheet to quickly switch between two stable states, it rapidly jumps from an extended state to a bent state, causing the flexible gripping capsule to quickly bend inward to cover the fruits and vegetables, significantly improving the response speed of the flexible gripper and overcoming the defect of lag in response of traditional flexible materials. The flexible gripping capsule is made of flexible material, forming flexible contact with the fruits and vegetables, which can effectively reduce damage to the surface of the fruits and vegetables during gripping. When releasing the fruits and vegetables, the linear drive source removes the thrust, and the bistable elastic sheet returns to the extended state under the action of elastic restoring force, and the flexible gripping capsule unfolds accordingly, completing the release action. The entire gripping process is responsive and reliable, enabling a complete work cycle of clamping and releasing. This device takes into account the three major requirements of rapid response, size adaptability, and non-destructive gripping, and is particularly suitable for the automated post-harvest processing of slender fruits and vegetables such as cucumbers, loofahs, and honeydew melons. It is of great significance to promoting the development of the fruit and vegetable industry. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0018] Figure 1 Front view of the present invention.

[0019] Figure 2 This is a three-dimensional structural schematic diagram of the present invention; Figure 3 This is a three-dimensional structural schematic diagram of the size adjustment device in this invention; Figure 4 This is a three-dimensional structural diagram of the drive cylinder and transmission component in this invention. Figure 5 This is a three-dimensional structural diagram of the transmission component in this invention; Figure 6 This is a three-dimensional structural schematic diagram of the vibration-absorbing connection component in this invention; Figure 7 This is a three-dimensional structural diagram of the sliding guide mechanism in this invention; Figure 8 This is a partial cross-sectional view of the linear drive source in this invention; Figure 9 This is a schematic diagram of the working principle of the linear drive source in this invention; Figure 10 This is a partial cross-sectional view of the flexible clamping capsule in this invention; Figure 11 This is a three-dimensional structural diagram of the invention in its initial state; Figure 12 This is a three-dimensional structural diagram of the present invention in the grasping state; Figure 13 This is a schematic diagram of the grasping space adjustment state of the present invention. Figure 1 ; Figure 14 This is a schematic diagram of the grasping space adjustment state of the present invention. Figure 2 ; In the diagram, 1. Fixed plate; 2. Size adjustment device; 3. Flexible gripping mechanism; 4. Mounting base; 5. Linear drive source; 6. Flexible clamping bladder; 7. Bistable elastic sheet; 8. Drive cylinder; 9. Transmission component; 10. Guide component; 11. Through hole; 12. Sliding guide mechanism; 13. Motion conversion mechanism; 14. Connecting frame; 15. Vibration-absorbing connecting assembly; 16. Sliding component; 17. First inclined slide; 18. Elastic plate; 19. Fixed block; 20. Guide rod; 21. Linear bearing; 22. Second inclined slide; 23. Mounting column; 24. Mounting block; 25. Slide bearing; 26. Moving bearing; 27. Radial slide; 28. Flexible airbag; 29. ​​Restricting component; 30. Flexible bladder body; 31. Drive chamber; 32. Sealed chamber. Detailed Implementation

[0020] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the content of the embodiments. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0021] Example 1: As Figures 1-14As shown, a bistable flexible vibration-absorbing gripper for fruits and vegetables with large aspect ratios includes a fixed plate 1, a size adjustment device 2, and multiple flexible gripping mechanisms 3 evenly distributed along the circumference. The size adjustment device 2 is mounted on the fixed plate 1 and is used to drive the multiple flexible gripping mechanisms 3 to synchronously change their radial positions to adjust the gripping space. Each flexible gripping mechanism 3 includes a mounting base 4, a linear drive source 5, and a flexible clamping capsule 6. The mounting base 4 is connected to the size adjustment device 2 and moves radially under the drive of the size adjustment device 2. A bistable elastic sheet 7 is provided inside the flexible clamping capsule 6. The bistable elastic sheet 7 has a first stable state and a second stable state. In the first stable state, the bistable elastic sheet 7 is in a straight state, and in the second stable state, the bistable elastic sheet 7 is in an inwardly bent state. The linear drive source 5 is mounted on the mounting base 4 and is used to apply force to the bistable elastic sheet 7, driving it to switch between the first stable state and the second stable state, thereby driving the flexible clamping capsule 6 to switch between the straight and bent states to achieve the clamping and release of fruits and vegetables.

[0022] Example 2: Figures 1-14 As shown, unlike Embodiment 1, the size adjustment device 2 includes a drive cylinder 8, a transmission component 9, and a guide component 10. The transmission component 9 is connected to the output end of the drive cylinder 8. The guide component 10 is fixed below the fixed plate 1, and a through hole 11 is provided in the center of the guide component 10. Each mounting seat 4 is connected to the guide component 10 through a sliding guide mechanism 12 and to the transmission component 9 through a motion conversion mechanism 13. The axial movement of the transmission component 9 is converted into the radial movement of the mounting seat 4 through the motion conversion mechanism 13.

[0023] In the above structure, the radial position of multiple flexible gripping mechanisms 3 is synchronously adjusted through a motion conversion mechanism, thereby adapting to fruits and vegetables with large length-to-diameter ratios of different sizes. The drive cylinder 8 serves as the power source, driving the transmission component 9 to move up and down axially. The axial movement of the transmission component 9 is converted into the radial movement of the mounting base 4 through the motion conversion mechanism 13, enabling the multiple flexible gripping mechanisms 3 to synchronously contract inward or expand outward, precisely adjusting the size of the gripping space. The guide component 10 is fixed below the fixed plate 1, with a through hole 11 in its center, providing space for fruits and vegetables with large length-to-diameter ratios to pass through, facilitating accurate positioning and stable gripping of slender fruits and vegetables by the gripper. The mounting base 4 is connected to the guide component 10 through a sliding guide mechanism 12, which stably guides the radial movement of the mounting base 4, ensuring that the multiple flexible gripping mechanisms 3 maintain a uniformly distributed circumferential state and smooth movement during adjustment.

[0024] The above-mentioned design scheme of converting axial motion into radial motion is compact and reliable in transmission. By adjusting the extension and retraction stroke of the drive cylinder 8, the gripping space can be infinitely adjusted, enabling the gripper to adapt to fruits and vegetables of different diameters, from small to large, and significantly improving the gripper's adaptability to targets of different sizes.

[0025] In this embodiment, the motion conversion mechanism 13 includes a connecting frame 14 and a vibration-absorbing connecting assembly 15. The connecting frame 14 is fixedly connected to the transmission component 9. The vibration-absorbing connecting assembly 15 is connected between the connecting frame 14 and the mounting base 4. The vibration-absorbing connecting assembly 15 is provided with a sliding component 16. The outer side of the mounting base 4 is provided with a first inclined slide rail 17 that slopes outward from top to bottom. The sliding component 16 slides in cooperation with the first inclined slide rail 17. When the drive source drives the transmission component 9 and the connecting frame 14 to move axially, the vibration-absorbing connecting assembly 15 moves axially synchronously with the connecting frame 14. The sliding component 16 slides along the first inclined slide rail 17, pushing the mounting base 4 to move radially.

[0026] In the above structure, the connecting frame 14 is fixedly connected to the transmission component 9 and moves axially up and down together with the transmission component 9. The vibration-absorbing connecting assembly 15 is connected between the connecting frame 14 and the mounting base 4, playing a dual role of motion transmission and vibration absorption. The outer side of the mounting base 4 is provided with a first inclined slide 17 that slopes outward from top to bottom. Thus, when the drive cylinder 8 drives the transmission component 9 and the connecting frame 14 to move axially downward, the vibration-absorbing connecting assembly 15 moves downward synchronously with the connecting frame 14. The sliding member 16 on the vibration-absorbing connecting assembly 15 slides along the first inclined slide 17. Under the inclined guidance of the inclined slide, the axial downward motion component is converted into a radially inward thrust, thereby pushing the mounting base 4 to move radially inward, realizing the reduction of the gripping space. Conversely, when the transmission component 9 and the connecting frame 14 move upward, the sliding member 16 slides upward along the first inclined slide 17. With the cooperation of the sliding guide mechanism 12, the mounting base 4 moves radially outward, realizing the expansion of the gripping space or the release of fruits and vegetables.

[0027] The aforementioned motion conversion method features a simple structure and reliable transmission. The motion conversion ratio can be flexibly controlled by adjusting the inclination angle of the inclined slide. The vibration-absorbing connection component 15, while transmitting motion, can absorb the impact and vibration generated during the motion process through its own elastic deformation, reducing the impact on the entire system, improving motion stability and service life, and providing a guarantee for the precise positioning and stable gripping of the flexible gripping mechanism 3.

[0028] In this embodiment, the vibration-absorbing connection assembly 15 includes an elastic plate 18 and a fixing block 19. One end of the elastic plate 18 is fixed to the lower end of the connecting frame 14, and the fixing block 19 is fixed to the other end of the elastic plate 18. The sliding member 16 is rotatably connected to the fixing block 19.

[0029] In the above structure, one end of the elastic plate 18 is fixed to the lower end of the connecting frame 14, and the other end is fixed to the fixing block 19, forming a cantilever elastic support structure. This structure can transmit motion and has good elastic deformation capability. Specifically, the fixing block 19 serves as the mounting carrier for the sliding member 16. The sliding member 16 is rotatably connected within the fixing block 19, allowing it to roll flexibly in the first inclined slide rail 17, reducing frictional resistance during motion and improving the efficiency and smoothness of motion conversion. When the connecting frame 14 drives the vibration-absorbing connecting assembly 15 to move axially, the fixing block 19 and the sliding member 16 move accordingly. The sliding member 16 slides along the first inclined slide rail 17 and pushes the mounting base 4 to move radially. During this process, the elastic plate 18, as the elastic connector between the connecting frame 14 and the fixing block 19, can absorb the impact and vibration energy generated during motion through its own elastic deformation, effectively mitigating the impact caused by sudden motion changes, protecting the transmission mechanism, and improving the stability of the system. The elastic deformation of the elastic plate 18 can also buffer the radial movement of the mounting base 4, avoiding vibration and noise that may be generated by rigid transmission, making the entire size adjustment process more stable and reliable.

[0030] Example 3: Figures 1-14 As shown, unlike Embodiment 2, the upper end of the connecting frame 14 is fixed with symmetrically distributed guide rods 20, and the fixing plate 1 is provided with symmetrically distributed linear bearings 21. The guide rods 20 and the corresponding linear bearings 21 are in sliding fit.

[0031] When the drive cylinder 8 drives the transmission component 9 and the connecting frame 14 to move axially, the guide rod 20 slides in the linear bearing 21. The linear bearing 21 constrains the movement trajectory of the guide rod 20, ensuring that the connecting frame 14 moves strictly up and down along the axial direction. This avoids radial offset or tilting sway of the connecting frame 14 during movement. The symmetrical distribution design enables the guide rod 20 to provide balanced support and constraint to the connecting frame 14, ensuring the balance and stability of the connecting frame 14 during movement and preventing uneven loading or jamming caused by uneven force.

[0032] In this embodiment, the side wall of the transmission component 9 is uniformly provided with multiple second inclined slides 22 that slope outward from top to bottom. The number of second inclined slides 22 is the same as the number of flexible gripping mechanisms 3. The sliding guide mechanism 12 includes a mounting post 23, a mounting block 24, and a slide bearing 25. The mounting post 23 is fixed to the upper end of the mounting base 4, the mounting block 24 is fixed to the upper end of the mounting post 23, and the slide bearing 25 is rotatably connected in the mounting block 24 and cooperates with the corresponding second inclined slide 22. The lower part of the mounting post 23 is also symmetrically provided with two movable bearings 26. The two movable bearings 26 are in rolling cooperation with the radial slides 27 provided on the guide component 10 to guide the radial movement of the mounting base 4.

[0033] In the above structure, multiple second inclined slides 22 are evenly arranged circumferentially on the side wall of the transmission component 9, sloping outward from top to bottom. The number of slides is the same as the number of flexible gripping mechanisms 3, ensuring that each mounting base 4 can obtain an independent and balanced driving force. The mounting column 23 is fixed to the upper end of the mounting base 4, and the mounting block 24 is fixed to the upper end of the mounting column 23. The slide bearing 25 is rotatably connected in the mounting block 24 and cooperates with the corresponding second inclined slide 22. When the transmission component 9 moves axially, the slide bearing 25 rolls in the second inclined slide 22. Under the inclined guidance of the slide, the axial movement of the transmission component 9 is converted into a radial driving force on the mounting base 4, pushing the mounting base 4 to move radially.

[0034] Two symmetrical movable bearings 26 are arranged at the lower part of the mounting column 23. These two movable bearings 26 roll into the radial slide rail 27 provided on the guide member 10, providing guiding constraints for the radial movement of the mounting base 4, ensuring that the mounting base 4 moves strictly in the radial direction without deviation or swaying. This dual guiding mechanism achieves motion conversion and radial drive through the cooperation of the slide bearing 25 and the second inclined slide rail 22, and provides motion guidance and trajectory constraint through the cooperation of the movable bearings 26 and the radial slide rail 27. The two work together to ensure the accuracy, smoothness and reliability of the movement of the mounting base 4.

[0035] In this embodiment, the linear drive source 5 includes a flexible airbag 28 and a limiting member 29. The flexible airbag 28 is disposed on the mounting base 4, and one end of the flexible airbag 28 is connected to the flexible clamping bladder 6. The limiting member 29 is wrapped around the outer wall of the flexible airbag 28 to limit the radial expansion of the flexible airbag 28 and guide it to extend axially. When the flexible airbag 28 is inflated, the flexible airbag 28 expands radially and extends axially, driving the bistable elastic sheet 7 to quickly switch from the first stable state to the second stable state. When the flexible airbag 28 is deflated, the flexible airbag 28 shortens axially, and the bistable elastic sheet 7 resets from the second stable state to the first stable state under the action of elastic restoring force, driving the flexible clamping bladder 6 to return to the straightened state.

[0036] The linear drive source 5 employs a driving method that combines a flexible airbag 28 with a limiting member 29, achieving rapid and reliable driving of the bistable elastic sheet 7. The flexible airbag 28 is mounted on the mounting base 4, with one end connected to the flexible clamping bladder 6, forming a complete pneumatic drive transmission chain. The limiting member 29 is wound around the outer wall of the flexible airbag 28, playing a crucial role in constraining and guiding the deformation of the flexible airbag 28. When the flexible airbag 28 is inflated, the limiting member 29 restricts its excessive radial expansion, guiding the flexible airbag 28 to expand moderately in the radial direction while mainly elongating in the axial direction. This deformation mode has the following effects: the radial expansion of the flexible airbag 28 increases its end face area, generating a greater axial thrust under the same air pressure conditions, while the axial elongation causes the end of the flexible airbag 28 to move forward, applying a concentrated thrust to the middle of the bistable elastic sheet 7 inside the flexible clamping bladder 6. When the thrust reaches the critical switching force of the bistable elastic sheet 7, the strain energy stored in the elastic sheet is rapidly released, driving the bistable elastic sheet 7 to jump instantaneously from the straight first stable state to the bent second stable state, causing the flexible clamping bladder 6 to quickly bend inward to complete the grasping action.

[0037] The aforementioned bistable rapid switching mechanism significantly improves the response speed of the flexible gripper, overcoming the inherent defect of slow response in traditional flexible pneumatic grippers. The release process is also highly efficient and reliable. When the flexible airbag 28 deflates, its axial shortening removes the thrust on the bistable elastic plate 7. Under the action of its own elastic restoring force, the bistable elastic plate 7 resets from the second stable state to the first stable state, driving the flexible clamping bladder 6 to return to the straight state, completing the release of fruits and vegetables. The entire process only requires adjusting the air pressure to achieve the switching between gripping and releasing. It has a fast response speed and reliable operation, making it particularly suitable for high-frequency repetitive operations in automated fruit and vegetable production lines.

[0038] In this embodiment, the limiting member 29 includes multiple winding lines, which are wound around the outer wall of the flexible airbag 28 in clockwise and counterclockwise directions at a 45° helix angle, respectively, to prevent the flexible airbag 28 from rupturing due to excessive radial deformation, and to enable the flexible airbag 28 to undergo simultaneous radial expansion and axial elongation deformation when inflated.

[0039] Multiple spiral threads are wound in a 45° helix angle, crisscrossing clockwise and counterclockwise directions on the outer wall of the flexible airbag 28, forming a grid-like constraint structure. This bidirectional spiral winding method can create a uniformly distributed constraint force on the surface of the flexible airbag 28. The 45° helix angle is a key parameter optimized in the design. This angle allows the spiral threads to simultaneously constrain deformation in both the radial and axial directions when the flexible airbag 28 is inflated. When the internal air pressure of the flexible airbag 28 increases, the spiral threads limit the excessive radial expansion of the airbag, preventing stress concentration or even rupture failure due to over-expansion. At the same time, due to the presence of the helix angle, the constraint effect of the spiral threads guides the flexible airbag 28 to convert some of the expansion energy into axial elongation deformation, enabling the flexible airbag 28 to simultaneously undergo moderate radial expansion and significant axial elongation during inflation.

[0040] The aforementioned deformation mode ensures both the increase in the end face area of ​​the flexible airbag 28 to enhance the axial output force and sufficient axial elongation to effectively drive the bistable elastic sheet 7. The cross structure of clockwise and counterclockwise bidirectional winding also improves the uniformity and stability of the constraint, avoiding the airbag torsion or uneven local stress that may be caused by unidirectional winding.

[0041] Example 4: Figures 1-14 As shown, unlike Embodiment 3, the flexible clamping capsule 6 includes a flexible capsule body 30, and a bistable elastic sheet 7 is fixed inside the flexible capsule body 30, dividing the flexible capsule body 30 into a driving chamber 31 and a sealing chamber 32. The driving chamber 31 is located on one side close to the linear driving source 5, and the sealing chamber 32 is located on the other side and is sealed. The sealing chamber 32 is filled with gas.

[0042] The flexible clamping capsule 6 adopts a dual-chamber structure, achieving both rapid driving and vibration absorption functions through the ingenious arrangement of bistable elastic plates 7. The flexible capsule body 30 serves as the main structure of the flexible clamping capsule 6, with the bistable elastic plates 7 fixed inside, dividing the entire flexible capsule body 30 into two independent functional areas: a driving chamber 31 and a sealed chamber 32. The driving chamber 31, located near the linear drive source 5, is the working area where the bistable elastic plate 7 receives thrust and switches states. When the flexible airbag 28 of the linear drive source 5 inflates and extends, its end applies thrust to the middle of the bistable elastic plate 7 within the driving chamber 31, driving the bistable elastic plate 7 to quickly switch from the first stable state to the second stable state, causing the entire flexible clamping capsule 6 to quickly bend inward to complete the grasping action. The sealed chamber 32 is located on the other side of the flexible bladder body 30 and is completely sealed. It is filled with gas and forms a closed air cushion structure. When the flexible clamping bladder 6 bends inward rapidly due to the rapid switching of the bistable elastic sheet 7 and comes into contact with the fruits and vegetables, the gas in the sealed chamber 32 is compressed. This gas compression process can effectively absorb the impact energy generated when the bistable elastic sheet 7 jumps rapidly and the vibration energy generated when the flexible clamping bladder 6 collides with the fruits and vegetables, playing a buffering and protective role and significantly reducing the impact damage to the surface of the fruits and vegetables.

[0043] In this embodiment, both the flexible airbag 28 and the flexible clamping bladder 6 are made of thermoplastic elastomer material with a Shore hardness of 90A through 3D printing.

[0044] The thermoplastic elastomer material with a Shore hardness of 90A has moderate hardness and good elasticity. It can withstand the internal air pressure during inflation without excessive deformation or damage, and it also has enough softness to achieve flexible contact with fruits and vegetables, effectively reducing damage to the surface of fruits and vegetables. The material with this hardness level can maintain stable mechanical properties during repeated inflation and deflation cycles, and is not prone to fatigue failure, thus extending the service life of the flexible airbag 28 and the flexible clamping bladder 6. The thermoplastic elastomer material has excellent airtightness, which can ensure that the flexible airbag 28 maintains a stable internal air pressure when inflated, while ensuring the long-term sealing performance of the sealed chamber 32 of the flexible clamping bladder 6 and maintaining its shock absorption and buffering function.

[0045] The gripper's complete gripping process for fruits and vegetables with large aspect ratios includes three stages: size adjustment, rapid clamping, and release. In the preparation stage before gripping, based on the diameter of the fruit or vegetable to be gripped, the drive cylinder 8 drives the transmission component 9 to move axially. The motion conversion mechanism 13 converts the axial motion into the radial motion of multiple flexible gripping mechanisms 3, causing the mounting base 4 to move synchronously radially, adjusting the gripping space size to fit the diameter of the target fruit or vegetable. When fruits and vegetables enter the gripping space through the through hole 11 in the center of the guide 10, the flexible airbag 28 begins to inflate. Under the constraint and guidance of the restrictor 29, the flexible airbag 28 undergoes radial expansion and axial elongation, increasing its end face area and generating greater axial thrust. At the same time, the axial elongation propels its end forward, applying concentrated thrust to the middle of the bistable elastic sheet 7 inside the flexible gripping bladder 6. When the thrust reaches the critical value, the strain energy stored in the bistable elastic sheet 7 is rapidly released, instantly jumping from the first stable state of straightening to the second stable state of bending. This rapid switching action causes multiple flexible gripping bladders 6 to bend inward almost simultaneously and rapidly, forming a wrapping grip that firmly holds the fruits and vegetables.

[0046] During the clamping process, the gas in the sealed chamber 32 of the flexible clamping bladder 6 is compressed, absorbing the impact energy generated by the rapid jump of the bistable elastic sheet 7 and the vibration energy from the collision with the fruits and vegetables. The elastic plate 18 of the vibration-absorbing connection component 15 also undergoes elastic deformation to absorb vibration a second time. The dual vibration absorption mechanism effectively reduces damage to the surface of the fruits and vegetables.

[0047] After completing the handling task, the flexible airbag 28 deflates, shortens axially, and removes the thrust on the bistable elastic plate 7. Under the action of elastic restoring force, the bistable elastic plate 7 resets from the second stable state to the first stable state, driving the flexible clamping bladder 6 to return to the straight state, smoothly releasing the fruits and vegetables, and completing the entire gripping cycle.

[0048] This device is particularly suitable for gripping long and thin fruits and vegetables with a large aspect ratio (such as cucumbers, loofahs, honeydew melons, eggplants, etc.). This adaptability is reflected in several aspects. Because the length of long and thin fruits and vegetables is much greater than their diameter, traditional grippers often struggle to create a stable grip. However, this gripper, through its size adjustment device 2, can flexibly adjust the gripping space according to the diameter of the fruit or vegetable, ensuring that multiple flexible gripping capsules 6 can fully contact the surface of the fruit or vegetable, forming a multi-point support evenly distributed along the circumference. This multi-point enveloping gripping method can generate a stable gripping force in the radial direction of the fruit or vegetable, effectively preventing slippage and swaying of long and thin fruits and vegetables during handling due to gravity or inertia. The through hole 11 in the center of the guide 10 allows long and thin fruits and vegetables to pass longitudinally through the gripper. The gripper can grasp the fruit or vegetable at an appropriate position along its length, selecting the center of gravity or structurally stable part of the fruit or vegetable for gripping, further improving the stability of the grip. The flexible gripping capsule 6 is made of flexible material, enabling it to form a large area of ​​flexible contact with the surface of slender fruits and vegetables. The uniform stress distribution avoids localized stress concentration and skin damage that can occur with rigid grippers. The rapid switching mechanism of the bistable elastic sheet 7 allows the gripper to quickly complete the gripping action, shortening the gripping time and improving work efficiency. The dual vibration absorption mechanism ensures that fragile fruits and vegetables are not damaged by impact during rapid gripping. The design of multiple flexible gripping mechanisms 3, evenly distributed along the circumference and synchronously adjustable radially, allows the gripper to adapt to significant differences in diameter among fruits and vegetables with large aspect ratios. Whether it's a small cucumber or a large eggplant, appropriate gripping space and force can be obtained through adjustment, greatly improving the gripper's versatility and adaptability, and meeting the practical needs of automated post-harvest processing of fruits and vegetables for multiple uses.

[0049] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A bi-stable compliant vibration absorption gripper for large aspect ratio fruits and vegetables, characterized by: The device comprises a fixed plate, a size adjusting device and a plurality of flexible gripping mechanisms distributed along the circumferential direction, the size adjusting device is arranged on the fixed plate and is used to drive the plurality of flexible gripping mechanisms to change the radial position synchronously to adjust the gripping space, each flexible gripping mechanism comprises a mounting base, a linear driving source and a flexible clamping capsule, the mounting base is connected with the size adjusting device and moves along the radial direction under the driving of the size adjusting device, the flexible clamping capsule is provided with a bistable elastic sheet, the bistable elastic sheet has a first stable state and a second stable state, in the first stable state, the bistable elastic sheet is in the straightened state, in the second stable state, the bistable elastic sheet is in the inwardly curved state, the linear driving source is arranged on the mounting base and is used to apply force to the bistable elastic sheet to drive the bistable elastic sheet to switch between the first stable state and the second stable state, thereby driving the flexible clamping capsule to switch between the straightened state and the curved state to realize the clamping and releasing of fruits and vegetables.

2. A bi-stable compliant vibration absorption gripper for long aspect ratio produce as claimed in claim 1, wherein: The size adjusting device comprises a driving cylinder, a transmission member and a guide member, the transmission member is connected with the output end of the driving cylinder, the guide member is fixed below the fixed plate, a through hole is formed in the center of the guide member, each mounting base is connected with the guide member through a sliding guide mechanism and is connected with the transmission member through a motion conversion mechanism, the axial motion of the transmission member is converted into the radial motion of the mounting base through the motion conversion mechanism.

3. A bi-stable compliant vibration absorption gripper for long aspect ratio produce as claimed in claim 2, wherein: The motion conversion mechanism comprises a connecting frame and a vibration absorption connecting assembly, the connecting frame is fixedly connected with the transmission member, the vibration absorption connecting assembly is connected between the connecting frame and the mounting base, a sliding member is arranged on the vibration absorption connecting assembly, a first inclined slide is arranged on the outside of the mounting base and inclines outward from top to bottom, the sliding member is in sliding fit with the first inclined slide, when the driving source drives the transmission member and the connecting frame to move along the axial direction, the vibration absorption connecting assembly moves along the axial direction synchronously with the connecting frame, the sliding member slides along the first inclined slide to push the mounting base to move along the radial direction.

4. A bi-stable compliant vibration absorption gripper for long aspect ratio produce according to claim 3, wherein: The vibration absorption connecting assembly comprises an elastic plate and a fixed block, one end of the elastic plate is fixed to the lower end of the connecting frame, the fixed block is fixed to the other end of the elastic plate, and the sliding member is rotatably connected in the fixed block.

5. A bi-stable compliant vibration absorption gripper for long aspect ratio produce as claimed in claim 3, wherein: The upper end of the connecting frame is fixed with symmetrically distributed guide rods, the fixed plate is provided with symmetrically distributed linear bearings, and the guide rods are in sliding fit with the corresponding linear bearings.

6. A bi-stable compliant vibration absorption gripper for long aspect ratio produce as claimed in claim 2, wherein: The side wall of the transmission member is uniformly provided with a plurality of second inclined slides inclined outward from top to bottom in the circumferential direction, the number of the second inclined slides is the same as the number of the flexible gripping mechanism, the sliding guide mechanism comprises a mounting column, a mounting block and a slide bearing, the mounting column is fixed at the upper end of the mounting seat, the mounting block is fixed at the upper end of the mounting column, the slide bearing is rotatably connected in the mounting block and matched with the corresponding second inclined slide, the lower part of the mounting column is also symmetrically provided with two moving bearings, the two moving bearings are rolling matched with the radial slides provided on the guide member, for guiding the radial movement of the mounting seat.

7. The bi-stable compliant vibration absorption gripper for long aspect ratio produce according to claim 1, wherein: The linear driving source comprises a flexible air bag and a limiting member, the flexible air bag is arranged on the mounting seat, one end of the flexible air bag is connected with the flexible clamping capsule, the limiting member is wound on the outer wall of the flexible air bag, for limiting the radial expansion of the flexible air bag and guiding its axial elongation; when the flexible air bag is inflated, the flexible air bag is radially expanded and axially elongated, driving the bistable elastic sheet to quickly switch from the first stable state to the second stable state; when the flexible air bag is deflated, the flexible air bag is axially shortened, and the bistable elastic sheet is reset from the second stable state to the first stable state under the action of the elastic restoring force, driving the flexible clamping capsule to return to the straightened state.

8. A bi-stable compliant vibration absorption gripper for long aspect ratio produce according to claim 7, wherein: The limiting member comprises a plurality of winding wires, the winding wires are wound on the outer wall of the flexible air bag in the clockwise direction and the counterclockwise direction respectively at a 45° spiral angle, for preventing the flexible air bag from being ruptured due to excessive radial deformation, and enabling the flexible air bag to simultaneously radially expand and axially elongate when inflated.

9. The bi-stable compliant vibration absorption gripper for long aspect ratio produce according to claim 1, wherein: The flexible clamping capsule comprises a flexible capsule body, the bistable elastic sheet is fixed in the flexible capsule body, dividing the flexible capsule body into a driving chamber and a sealed chamber, the driving chamber is located on one side close to the linear driving source, and the sealed chamber is located on the other side and is sealed, the sealed chamber is filled with gas.

10. The bi-stable compliant vibration absorption gripper for large aspect ratio fruits and vegetables of claim 7, wherein: The flexible air bag and the flexible clamping capsule are both made of thermoplastic elastomer material with a Shore hardness of 90A by 3D printing.

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