Magneto-rheological bionic bristle contact pad, grabbing manipulator and grabbing control method

Abstract

The invention relates to the technical field of manipulators with finger-shaped piece chucks, in particular to a magneto-rheological bionic bristle contact pad, a grabbing manipulator and a grabbing control method. According to the magnetorheological bionic bristle contact pad, Van der Waals force passively generated based on a bristle structure is organically combined with the characteristic that the state of the magnetorheological fluid can be rapidly changed, and rigidity control over bionic bristles is achieved by means of the characteristic of the magnetorheological fluid; when being applied to a manipulator, the self-adaptive grabbing device can be self-adaptive to the surface of a grabbed object and generate dry adhesion, the grabbing force can be accurately controlled and kept in the grabbing process, the self-adaptive grabbing device can be self-adaptive to the surface of the grabbed object, the surface of the grabbed object is not damaged, meanwhile, the grabbing force can be controlled in the grabbing process, and the grabbing efficiency is improved. And the grabbing quality and efficiency are improved.

Description

Technical Field

[0001] This invention relates to the field of robotic arms with finger-shaped grippers, and more particularly to magnetorheological biomimetic bristle pads, gripping robotic arms, and gripping control methods. Background Technology

[0002] With the continuous development of intelligent agriculture, harvesting robots have become commonly used intelligent equipment for fruit picking. When harvesting fruit, these robots not only need to quickly identify and accurately pick the fruit, but also ensure that the fruit is not damaged during the entire harvesting process to guarantee fruit quality. For hard-skinned fruits such as apples and pears, traditional robotic arms with rigid grippers can be used for picking. However, for soft-skinned fruits and vegetables such as tomatoes and peaches, rigid grippers can easily cause the skin to crack and be damaged, thus affecting fruit quality during harvesting.

[0003] To address the aforementioned issues, existing technologies employ vacuum adsorption robotic arms, utilizing negative pressure adsorption to avoid mechanical squeezing when picking fruits and vegetables. While this avoids damage caused by rigid mechanical structures, the irregular shapes of fruit and vegetable surfaces result in high energy consumption for establishing a large vacuum negative pressure, sometimes exceeding 160W. Furthermore, for soft-skinned fruits and vegetables with porous surfaces, such as kiwifruit, airflow leakage on the peel surface is severe, significantly reducing the adsorption effect.

[0004] Existing technologies also include forming bristle structures on the gripper surface of robotic arms that mimic the feet of geckos, spiders, or other insects. These bristles generate van der Waals forces to achieve adhesion and gripping. While this method can adapt to complex curved surfaces and achieve uniform force distribution on such surfaces, the van der Waals forces between the gripper and the fruit / vegetable surface are passive adhesive forces. This makes it difficult to control the force during the picking process, such as maintaining the gripping force during picking or releasing it when placing the fruit / vegetable after picking. Although this can prevent damage to the fruit / vegetable surface during picking, it significantly reduces harvesting efficiency. Summary of the Invention

[0005] The purpose of this invention is to provide a magnetorheological biomimetic bristle pad to solve the problem of uncontrollable grasping force in the bristle structure used in existing mechanical grippers.

[0006] Meanwhile, the present invention also aims to provide a gripping robot that uses the above-mentioned magnetorheological biomimetic bristle pad to solve the problem that the existing mechanical claws with bristle structures have low picking efficiency due to the uncontrollable gripping force.

[0007] Furthermore, the present invention aims to provide a gripping control method for controlling the aforementioned gripping robot, thereby solving the problem that the gripping force of existing mechanical claws with bristle structures is difficult to control.

[0008] The magnetorheological biomimetic bristle touch pad of the present invention adopts the following technical solution: The magnetorheological biomimetic bristle pad of the present invention includes a main pad body, which has a magnetorheological fluid cavity for containing magnetorheological fluid. One side surface of the main pad body is provided with an array of micropores communicating with the magnetorheological fluid cavity. Each micropore is provided with a biomimetic bristle, so that the side surface of the main pad body forms a bristle palm covered with biomimetic bristles, so that it can dryly adhere to the object by van der Waals forces when in contact with the object. The biomimetic bristles have bristle cavities communicating with the corresponding micropores for being filled with magnetorheological fluid. An excitation component is provided in the main pad body or on the surface of the main pad body, so that when the excitation component is energized and magnetized, all the biomimetic bristles harden, so as to realize the shape-conforming retention of the bristle palms on the object surface.

[0009] The beneficial effects of the above technical solution are as follows: One side of the main body of the magnetorheological bionic bristle contact pad has an array of bionic bristles. When the magnetorheological bionic bristle contact pad is applied to a mechanical gripper, the bionic bristles can adapt to the surface of the object being gripped (such as the irregular outer surface of fruits and vegetables) and generate van der Waals forces between the contact surface and the object, achieving dry adhesion. Moreover, the bionic bristles have bristle cavities that are identical to and filled with magnetorheological fluid in the main body. After the magnetorheological bionic bristle contact pad adheres to the object being gripped, a magnetic field is generated by supplying power to the excitation component to harden the magnetorheological fluid. This increases the stiffness of the bionic bristles that conform to the surface of the object being gripped, further enhancing the adhesion and achieving reliable gripping and holding. When it is necessary to release the object being gripped, the magnetic field is reduced or removed to liquefy the magnetorheological fluid, thereby reducing the stiffness of the bionic bristles and weakening the adhesion to the object, so as to quickly release the object.

[0010] The above technical solution organically combines the van der Waals force passively generated by the bristle structure with the rapid state change characteristics of magnetorheological fluid. By leveraging the properties of magnetorheological fluid, the stiffness of the biomimetic bristles can be controlled, thereby controlling the adhesion force at the adhesion interface. When applied to a robotic arm, it can adapt to the surface of the object being grasped and generate dry adhesion. Furthermore, it can precisely control and maintain the magnitude of the grasping force during the grasping process. It can adapt to the surface of the object being grasped without damaging the surface, while controlling the grasping force during the grasping process, thus improving the grasping quality and efficiency.

[0011] Furthermore, the bristle cavity extends from the root of the biomimetic bristle to near the tip.

[0012] The beneficial effects of the above technical solution are as follows: This can effectively control the stiffness of the entire bionic bristle. When the overall stiffness is increased, a conformal support is formed between the side of the main pad and the surface of the object being grasped, thus effectively maintaining the grasping force. When the overall stiffness is decreased, the force is unloaded between the side of the main pad and the surface of the object being grasped, making it easier to quickly release the object being grasped.

[0013] Furthermore, the biomimetic bristles are mushroom-shaped, including straight bristle bodies and mushroom heads at the ends of the bristle bodies. The bristle cavities include the bristle cavities within the bristle bodies and the head cavities within the mushroom heads.

[0014] The beneficial effects of the above technical solution are as follows: the mushroom-shaped bionic bristles make contact with the surface of the object being grasped through the mushroom head. With the help of the spherical outer surface of the mushroom head, they can better adapt to and fit the irregular surface of the object being grasped. This allows each bionic bristle to adaptively deform according to the three-dimensional shape of its contact point and fit with the surface of the object being grasped, ensuring the reliability of the fit.

[0015] Furthermore, the shape of the head cavity is consistent with the shape of a mushroom head.

[0016] The beneficial effects of the above technical solution are: it ensures that the wall thickness of the mushroom head remains as consistent as possible, thus guaranteeing better rigidity consistency with the contact surface of the object being grasped.

[0017] Furthermore, the bristles of each biomimetic bristle are tilted toward one side of the main pad, and the mushroom head of each biomimetic bristle protrudes outward perpendicular to the side of the main pad.

[0018] The beneficial effects of the above technical solution are: the tilt direction of each biomimetic bristle is consistent, and it can deform to the same side when it comes into contact with the surface of the object being grasped, resulting in good consistency of the grasping force direction and a more stable grasping process.

[0019] Furthermore, the biomimetic bristles have a thin-walled structure.

[0020] The beneficial effects of the above technical solution are: the biomimetic bristles with thin walls not only save materials, but also have higher softness when the magnetorheological fluid is in a liquefied state and higher stiffness when the magnetorheological fluid is in a hardened state. This avoids material waste due to excessive wall thickness and avoids affecting the stability of gripping when greater stiffness and stable gripping are required due to the softness of the material itself.

[0021] Furthermore, the main pad is a flexible pad, and the side of the main pad is provided with an array of protrusions. The micropores are arranged in the middle of each protrusion to form a micropore array, and the protrusions are separated by a gap groove.

[0022] The beneficial effects of the above technical solution are as follows: the arrangement of the protrusion array enables each bionic bristle to have its own root stability structure, so that when the head of each bionic bristle is squeezed and deformed, the root will not deform too much. At the same time, with the help of the spacing groove, the roots of adjacent bionic bristles are not affected, ensuring that each bionic bristle can adapt its deformation based on the contact point with the object being grasped, thus ensuring a close fit.

[0023] Furthermore, a mechanical sensor is provided at the bottom of the main pad to monitor the normal and tangential forces at the adhesion interface in real time.

[0024] The beneficial effects of the above technical solution are as follows: By setting a mechanical sensor at the bottom of the main pad, the reverse force and tangential force of the adhesion interface can be monitored in real time. During use, it can work with the control module to monitor the error and change of the gripping force, so that the control module can control the excitation module to adjust the magnetic field size, thereby realizing the stiffness adjustment of the biomimetic bristles and ensuring the stability of the gripping process.

[0025] Furthermore, the main pad includes a magnetorheological control layer and a biomimetic adhesive layer and a flexible base layer respectively bonded to its two sides. The magnetorheological control layer has a hollow structure, and the internal cavity constitutes the magnetorheological fluid cavity. The micropore array is provided on the biomimetic adhesive layer and connected to biomimetic bristles. The wall surface of the magnetorheological control layer that is bonded to the biomimetic adhesive layer has a connecting channel connecting each micropore and the magnetorheological fluid cavity. The flexible base layer is used to connect with the grasping fingers of the robotic arm. The excitation component is a flat excitation coil provided on the biomimetic adhesive layer and / or the flexible base layer to generate a magnetic field perpendicular to the main pad.

[0026] The beneficial effects of the above technical solution are as follows: the main pad is formed by bonding three functional layers: a magnetorheological control layer, a biomimetic adhesive layer, and a flexible substrate layer. The excitation coil, which serves as the excitation component, is arranged on the biomimetic adhesive layer and / or the flexible substrate layer. Each functional layer can be manufactured separately, which reduces the manufacturing difficulty of the main pad.

[0027] Furthermore, the flexible substrate is a millimeter-scale flexible layer, and the mechanical sensor is a multi-point distributed thin-film force sensor embedded inside the flexible substrate.

[0028] The beneficial effects of the above technical solution are: embedding the mechanical sensor in a millimeter-scale flexible substrate layer is not only easy to manufacture, but also enables relatively accurate detection of the force transmitted from the adhesion interface through biomimetic bristles, providing accurate data support for adjusting the magnetic field strength.

[0029] Furthermore, the diameter of the mushroom head of the biomimetic bristles is between 200-500 nm, the diameter of the bristle body is between 100-200 nm, the height is between 1-2 μm, and the array spacing is between 300-600 nm.

[0030] The beneficial effects of the above technical solution are as follows: By setting the size and arrangement of the biomimetic bristles in this way, more contact points can be formed within the limited contact area between the magnetorheological biomimetic bristle pad and the object being grasped, so that the ends of each biomimetic bristle form a contoured cloud of contact points, thereby improving the reliability and stability of grasping the object being grasped.

[0031] The gripping robot of the present invention adopts the following technical solution: The gripping manipulator of the present invention includes a base, a gripping arm, and a gripping hand. The gripping hand includes a gripping palm and multiple gripping fingers. At least some of the gripping fingers have magnetorheological biomimetic bristle pads at their fingertips. The magnetorheological biomimetic bristle pads include a main pad body with a magnetorheological fluid cavity for containing magnetorheological fluid. One side surface of the main pad body has an array of micropores communicating with the magnetorheological fluid cavity. Each micropore is provided with biomimetic bristles, so that the side surface of the main pad body is covered with biomimetic bristles. The biomimetic bristles are designed to adhere to objects dryly via van der Waals forces upon contact. Each bristle has an internal cavity that communicates with corresponding micropores to be filled with magnetorheological fluid. An excitation component is provided inside or on the surface of the main pad to harden all the biomimetic bristles when the excitation component is energized and magnetized, thereby enabling the bristle tentacles to maintain the shape of the object surface. A power supply for powering the magnetorheological biomimetic bristle pad and a control module for power supply control are installed on the base or gripping arm.

[0032] The beneficial effects of the above technical solution are as follows: The grasping finger tip of the above grasping robot is provided with a magnetorheological bionic bristle pad. One side of the main pad of the magnetorheological bionic bristle pad has an array of bionic bristles. Through the bionic bristles, it can adapt to the surface of the grasped object (such as the irregular outer surface of fruits and vegetables) and generate van der Waals force between the contact surface of the grasped object and the grasped object, so as to achieve dry adhesion. Moreover, the biomimetic bristles have the same magnetorheological fluid cavity as the main pad and are filled with magnetorheological fluid. After the magnetorheological biomimetic bristle pad adheres to the object being grasped, the magnetorheological fluid is hardened by supplying power to the excitation component to generate a magnetic field. This increases the stiffness of the biomimetic bristles that conform to the surface of the object being grasped, further enhancing the adhesion and achieving reliable grasping and holding. When it is necessary to release the object being grasped, the magnetorheological fluid is liquefied by reducing or removing the magnetic field, thereby reducing the stiffness of the biomimetic bristles and weakening the adhesion to the object being grasped, so as to quickly release the object being grasped.

[0033] The above technical solution organically combines the van der Waals force passively generated by the bristle structure with the rapid state change characteristics of magnetorheological fluid. By leveraging the properties of magnetorheological fluid, the stiffness of the biomimetic bristles can be controlled, thereby controlling the adhesion force at the adhesion interface. When applied to a robotic arm, it can adapt to the surface of the object being grasped and generate dry adhesion. Furthermore, it can precisely control and maintain the magnitude of the grasping force during the grasping process. It can adapt to the surface of the object being grasped without damaging the surface, while controlling the grasping force during the grasping process, thus improving the grasping quality and efficiency.

[0034] Furthermore, the bristle cavity extends from the root of the biomimetic bristle to near the tip.

[0035] The beneficial effects of the above technical solution are as follows: This can effectively control the stiffness of the entire bionic bristle. When the overall stiffness is increased, a conformal support is formed between the side of the main pad and the surface of the object being grasped, thus effectively maintaining the grasping force. When the overall stiffness is decreased, the force is unloaded between the side of the main pad and the surface of the object being grasped, making it easier to quickly release the object being grasped.

[0036] Furthermore, the biomimetic bristles are mushroom-shaped, including straight bristle bodies and mushroom heads at the ends of the bristle bodies. The bristle cavities include the bristle cavities within the bristle bodies and the head cavities within the mushroom heads.

[0037] The beneficial effects of the above technical solution are as follows: the mushroom-shaped bionic bristles make contact with the surface of the object being grasped through the mushroom head. With the help of the spherical outer surface of the mushroom head, they can better adapt to and fit the irregular surface of the object being grasped. This allows each bionic bristle to adaptively deform according to the three-dimensional shape of its contact point and fit with the surface of the object being grasped, ensuring the reliability of the fit.

[0038] Furthermore, the shape of the head cavity is consistent with the shape of a mushroom head.

[0039] The beneficial effects of the above technical solution are: it ensures that the wall thickness of the mushroom head remains as consistent as possible, thus guaranteeing better rigidity consistency with the contact surface of the object being grasped.

[0040] Furthermore, the bristles of each biomimetic bristle are tilted toward one side of the main pad, and the mushroom head of each biomimetic bristle protrudes outward perpendicular to the side of the main pad.

[0041] The beneficial effects of the above technical solution are: the tilt direction of each biomimetic bristle is consistent, and it can deform to the same side when it comes into contact with the surface of the object being grasped, resulting in good consistency of the grasping force direction and a more stable grasping process.

[0042] Furthermore, the biomimetic bristles have a thin-walled structure.

[0043] The beneficial effects of the above technical solution are: the biomimetic bristles with thin walls not only save materials, but also have higher softness when the magnetorheological fluid is in a liquefied state and higher stiffness when the magnetorheological fluid is in a hardened state. This avoids material waste due to excessive wall thickness and avoids affecting the stability of gripping when greater stiffness and stable gripping are required due to the softness of the material itself.

[0044] Furthermore, the main pad is a flexible pad, and the side of the main pad is provided with an array of protrusions. The micropores are arranged in the middle of each protrusion to form a micropore array, and the protrusions are separated by a gap groove.

[0045] The beneficial effects of the above technical solution are as follows: the arrangement of the protrusion array enables each bionic bristle to have its own root stability structure, so that when the head of each bionic bristle is squeezed and deformed, the root will not deform too much. At the same time, with the help of the spacing groove, the roots of adjacent bionic bristles are not affected, ensuring that each bionic bristle can adapt its deformation based on the contact point with the object being grasped, thus ensuring a close fit.

[0046] Furthermore, a mechanical sensor is provided at the bottom of the main pad to monitor the normal and tangential forces of the adhesion interface in real time. The mechanical sensor is connected to the control module to transmit the detected forces of the adhesion interface to the control module. The control module controls the power supply and the magnitude of the power supply current according to the magnitude of the forces.

[0047] The beneficial effects of the above technical solution are as follows: By setting a mechanical sensor at the bottom of the main pad, the reverse force and tangential force of the adhesion interface can be monitored in real time. During use, it can work with the control module to monitor the error and change of the gripping force, so that the control module can control the excitation module to adjust the magnetic field size, thereby realizing the stiffness adjustment of the biomimetic bristles and ensuring the stability of the gripping process.

[0048] Furthermore, the main pad includes a magnetorheological control layer and a biomimetic adhesive layer and a flexible base layer respectively bonded to its two sides. The magnetorheological control layer has a hollow structure, and the internal cavity constitutes the magnetorheological fluid cavity. The micropore array is provided on the biomimetic adhesive layer and connected to biomimetic bristles. The wall surface of the magnetorheological control layer that is bonded to the biomimetic adhesive layer has a connecting channel connecting each micropore and the magnetorheological fluid cavity. The flexible base layer is used to connect with the grasping fingers of the robotic arm. The excitation component is a flat excitation coil provided on the biomimetic adhesive layer and / or the flexible base layer to generate a magnetic field perpendicular to the main pad.

[0049] The beneficial effects of the above technical solution are as follows: the main pad is formed by bonding three functional layers: a magnetorheological control layer, a biomimetic adhesive layer, and a flexible substrate layer. The excitation coil, which serves as the excitation component, is arranged on the biomimetic adhesive layer and / or the flexible substrate layer. Each functional layer can be manufactured separately, which reduces the manufacturing difficulty of the main pad.

[0050] Furthermore, the flexible substrate is a millimeter-scale flexible layer, and the mechanical sensor is a multi-point distributed thin-film force sensor embedded inside the flexible substrate.

[0051] The beneficial effects of the above technical solution are: embedding the mechanical sensor in a millimeter-scale flexible substrate layer is not only easy to manufacture, but also enables relatively accurate detection of the force transmitted from the adhesion interface through biomimetic bristles, providing accurate data support for adjusting the magnetic field strength.

[0052] Furthermore, the diameter of the mushroom head of the biomimetic bristles is between 200-500 nm, the diameter of the bristle body is between 100-200 nm, the height is between 1-2 μm, and the array spacing is between 300-600 nm.

[0053] The beneficial effects of the above technical solution are as follows: By setting the size and arrangement of the biomimetic bristles in this way, more contact points can be formed within the limited contact area between the magnetorheological biomimetic bristle pad and the object being grasped, so that the ends of each biomimetic bristle form a contoured cloud of contact points, thereby improving the reliability and stability of grasping the object being grasped.

[0054] Furthermore, the grasping hand is equipped with a vision sensor for identifying the object being grasped. The vision sensor is connected to the control module and transmits visual information to the control module.

[0055] The beneficial effects of the above technical solution are as follows: the visual sensor can provide real-time feedback of environmental information, and by placing the visual sensor inside the grasping hand, the relative positional relationship between the grasping robot and the grasped object can be more accurately determined, so that the control module can control the movement of the grasping arm, thereby improving the accuracy and efficiency of grasping.

[0056] The grasping control method of the present invention adopts the following technical solution: The gripping control method of the present invention is applicable to the gripping robot arm of the above-mentioned technical solution, and includes the following steps: 1) Control the robotic arm to retract and grasp the object being grasped. The van der Waals force is formed by the adhesion between the magnetorheological biomimetic bristle pads at the tips of the grasping fingers and the surface of the object being grasped. 2) After grasping the object, monitor the force between the bristle pad of the magnetorheological bionic bristle contact pad and the adhesion interface of the object. When the force reaches the safe threshold range that can grasp without damaging the object, power the magnetorheological bionic bristle contact pad to harden the magnetorheological fluid and increase the stiffness of the bionic bristles to maintain the grasping state. 3) When it is necessary to put down the grasped object, cut off or reduce the power supply to the magnetorheological bionic bristle pad, reduce the stiffness of the bionic bristles, and open the grasping fingers to release and place the grasped object.

[0057] The beneficial effects of the above technical solution are as follows: When the gripping robot arm contacts and adheres to the object being gripped through the magnetorheological bionic bristle pads at the tips of its gripping fingers, it can form dry adhesion based on the van der Waals forces between the bionic bristles and the object being gripped. The entire pad can passively adapt to the surface shape of the object being gripped, thus conforming to the object's shape. When the force at the adhesion interface is within a safe threshold range, it means that the gripping force is sufficient to achieve stable gripping and movement of the object without damaging its surface. At this point, by hardening the magnetorheological fluid and increasing the stiffness of the bionic bristles, the tips of the gripping fingers form a rigid structure that conforms to the surface of the object being gripped, further improving the adhesion force at the adhesion interface and enabling reliable maintenance of the gripping force. When it is necessary to release and place the object being gripped, the stiffness of the bionic bristles is reduced by changing the hardness of the magnetorheological fluid, weakening the adhesion force at the adhesion interface, thereby achieving rapid release.

[0058] The above method uses magnetorheological fluid to control the hardness of biomimetic bristles, which can macroscopically control the microscopic forces, namely van der Waals forces, between the biomimetic bristles and the surface of the object being grasped. This efficiently enhances and maintains the grasping force while weakening the unloading force, thereby changing the passive and uncontrolled adhesion force into an active and controllable adhesion force. This improves the controllability of the grasping process and ensures that the grasping process is stable and efficient.

[0059] Furthermore, in step 2), during the process of grasping the object being grasped, the force between each magnetorheological bionic bristle contact pad and the adhesion interface of the object being grasped is monitored in real time. Fuzzy PID control is adopted to dynamically adjust the power supply current based on the force error and its rate of change.

[0060] The beneficial effects of the above technical solution are as follows: During the process of grasping the object being grasped, fuzzy PID control can dynamically adjust the macroscopic force in real time according to the magnitude and change of the microscopic force at the adhesion interface, thereby controlling the grasping force within a safe threshold range throughout the process, achieving stable grasping without damaging the surface of the object being grasped. Attached Figure Description

[0061] Figure 1This is a schematic diagram of one embodiment of the gripping robot of the present invention; Figure 2 for Figure 1 A schematic diagram of the structure of the middle-grip finger grasping mechanism; Figure 3 A schematic diagram of the magnetorheological biomimetic bristle touch pad; Figure 4 This is a schematic diagram illustrating the attachment and detachment states of the magnetorheological biomimetic bristle pad. Figure 5 A 3D model of biomimetic bristles; Figure 6 This is a front view of biomimetic bristles; Figure 7 for Figure 6 The left view; Figure 8 for Figure 6 Top view; Figure 9 This is a cross-sectional view of biomimetic bristles; Figure 10 for Figure 9 Enlarged view of the structure at point A in the middle; Figure 11 A schematic diagram showing the distribution of claw-like spikes on the surface of the mushroom head; Figure 12 A schematic diagram of the main cushion structure; Figure 13 Top view of the main pad body; Figure 14 A bottom view of the main cushion body; Figure 15 The front view of the main cushion body; Figure 16 for Figure 15 Sectional view at point D; Figure 17 for Figure 15 Sectional view at point B; Figure 18 for Figure 15 Sectional view at point C.

[0062] In the diagram: 1. Base; 2. Power supply; 3. Control module; 4. Air pump; 5. Air circuit; 6. Turntable bearing; 7. Rotary base; 8. Pitch servo; 9. Rotary servo; 10. Gripping arm; 11. Folding servo; 12. Telescopic cylinder; 13. Mechanical gripper base; 14. Gripping finger; 15. Gripping fingertip; 16. Vision sensor; 17. Constraint slot; 18. Retraction / extension linkage frame; 19. Hinge; 20. Finger body; 21. Finger root; 22. Constraint slide pin; 23. Finger... 24. End mounting base; 25. Magnetorheological bionic bristle touch pad; 26. Mechanical sensor; 27. Main pad body; 28. Micropore array; 29. ​​Bionic bristles; 30. Injection port; 31. Mushroom head; 32. Bristle body; 33. Magnetorheological fluid cavity; 34. Through-hole micropore; 35. Bristle inner cavity; 36. Head inner cavity; 37. Magnetorheological fluid; 38. Connecting port; 39. Claw; 40. Boss; 41. Spacing groove; 42. Magnetic coil; 43. Main channel; 44. Branch channel. Detailed Implementation

[0063] The specific embodiments of the present invention will be described below with reference to the accompanying drawings. It should be noted that, for ease of explanation, the directions such as "up," "down," "left," and "right" mentioned below refer to directions with respect to the overall direction. Figure 1 The directions shown are for reference only and are mainly used to indicate relative directions. They do not limit the actual orientation of the product during use, nor can they be used to limit the scope of protection of this invention.

[0064] Specific embodiments of the gripping robot of the present invention are as follows: Figure 1-2 As shown, the gripping robot includes a base 1, which serves as the supporting foundation for the entire gripping robot and is used for fixed installation on the mobile device to achieve material gripping, material transfer, and material release. A gripping arm 10 is mounted on the base 1, and a robotic hand is attached to the end of the gripping arm 10. The gripping arm 10 is a movable arm, capable of adjusting its spatial position relative to the base 1. The robotic hand includes a gripping palm and multiple gripping fingers 14 connected to the gripping palm. These fingers 14 can be driven to retract and open towards the palm, enabling the gripping and releasing of objects.

[0065] Specific examples Figure 1 As shown, the base 1 includes a plate-shaped seat, on which an arm base is mounted. A turntable bearing 6 is rotatably mounted on the arm base about a vertical axis, and a rotary seat 7 is fixedly mounted on the rotating ring of the turntable bearing 6. A rotary servo motor 9 is mounted on the arm base, and the rotary servo motor 9 is connected to the rotating ring for transmission, thereby driving the rotary seat 7 to rotate. Preferably, the rotary servo motor 9 can be a high-precision servo motor to ensure rotation accuracy. A pitch servo motor 8 is mounted at the middle of the rotary seat 7, and a pitch seat is connected to the action output component of the pitch servo motor 8. The gripping arm 10 is connected to the pitch seat and can be driven by the pitch seat to perform pitch movements.

[0066] The gripping arm 10 has a segmented structure, with adjacent segments connected by a folding servo motor 11. The folding servo motor 11 acts as a joint motor, enabling the arm to fold and extend. When the folding servo motor 11 is operating, it directly drives the arm segments, driven by its rotation output component, to rotate within a 270° range. Figure 1 As shown in the example, the gripping arm 10 comprises three sections, with folding servos 11 positioned between adjacent sections. The rotation axis of each folding servo 11 is parallel to the rotation axis of the pitch servo 8, enabling the gripping arm 10 to fold to a greater extent. Of course, in other embodiments, the rotation axis of the folding servo 11 can be perpendicular to the rotation axis of the pitch motor, and the rotation axes of different folding servos 11 can also be perpendicular, thereby achieving multi-dimensional motion.

[0067] Two of the three sections are structural sections, and one is a functional section. The structural section consists of a rigid arm body for physical connection, while the functional section not only provides physical connection but also motion control. Specifically, the functional section is located at the free end of the gripping arm 10 away from the pitch seat and is composed of a telescopic cylinder 12. The gripping hand of the robotic arm is mounted on the cylinder body of the telescopic cylinder 12, and the telescopic rod of the telescopic cylinder 12 is linked to the gripping fingers 14 movably mounted on the gripping hand, causing the gripping fingers 14 to retract and open. Of course, in other embodiments, the telescopic cylinder can be replaced with a telescopic hydraulic cylinder, or an electric push rod can be used. The fixed part of the electric push rod is connected to the gripping arm, the gripping hand is mounted on the fixed part of the electric push rod, and the telescopic rod of the electric push rod is driven to the gripping fingers.

[0068] Grasp fingers 14 Figure 2 As shown, it includes a curved finger body 20, one end of which is a finger root 21 and the other end is a finger tip. The finger root 21 of the grasping finger 14 is connected to the grasping palm. The bending direction and installation posture of the grasping finger 14 cause the finger tips of multiple grasping fingers 14 to approach each other and be distributed in a clustered manner.

[0069] The grasping hand includes a mechanical gripper base 13, which includes a central gripper base connected to a functional segment and finger connecting seats equal in number to the grasping fingers 14. The finger connecting seats extend outward from the central gripper base, and each finger connecting seat is radially connected to the central gripper base. The telescopic rod of the telescopic cylinder 12 passes through the central gripper base, that is, it passes through the center of the grasping hand. The finger connecting seats include a pair of arms that are parallel to each other in the circumferential direction of the central gripper base. A finger mounting groove is formed between the two pairs of arms for the finger roots 21 of the grasping fingers 14 to be inserted. Each pair of arms is provided with a radially extending constraint groove 17. The opening of the constraint groove 17 faces the circumferential side and is oriented towards the side of the finger root 21 of the grasping fingers 14. A constraint sliding pin 22 is fixed on the finger root 21 of the grasping fingers 14, and the constraint sliding pin 22 extends into the constraint groove 17. Based on the above structure, the root 21 of the grasping finger 14 can slide radially within the constraint groove 17, and the grasping finger 14 can rotate around the axis of the constraint pin 22.

[0070] The telescopic rod of the telescopic cylinder 12 passes through the central claw seat and is connected to a retraction linkage frame 18. The retraction linkage frame 18 is located within the space surrounded by multiple grasping fingers 14. The retraction linkage frame 18 is provided with radially outwardly extending hinge arms corresponding to each grasping finger 14. The middle region of the grasping finger 14 has a hinge portion 19, which is hinged to the hinge arm. The hinge portion 19 is closer to the finger root 21 than the finger tip. When the telescopic rod extends through the grasping palm, the finger root 21 slides radially outward along the constraint groove 17, and the finger tip of the grasping finger 14 rotates radially inward around the hinge portion 19 to perform the grasping action. When the telescopic rod retracts through the grasping palm, the finger root 21 slides radially inward along the constraint groove 17, and the finger tip of the grasping finger 14 rotates radially outward around the hinge portion 19 to perform the releasing action.

[0071] The base 1 is equipped with a power supply 2, an air pump 4, and a control module 3. The air pump 4 is connected to the telescopic cylinder 12 via an air passage 5, supplying air to the telescopic cylinder 12 to drive its telescopic movement. The power supply 2 provides power to the electrical components of the entire gripping robot. The control module 3 controls the air supply lines connecting the various servo motors and the telescopic cylinder 12. In one embodiment, the control module 3 can use an STM-32 control board, which is cost-effective, has low power consumption, and enables human-machine interaction, possessing high-performance computing capabilities. Of course, this invention does not exclude the use of other controllers such as a 51 microcontroller, ESP32 controller, PIC controller, MSP430 controller, etc., for the control module 3.

[0072] like Figure 1-2As shown, in this embodiment, the robotic hand is a three-claw robotic hand, meaning it has three grasping fingers 14, which are evenly spaced along the circumference of the grasping palm. A fingertip mounting base 23 is installed at the tip of each grasping finger 14, and a magnetorheological biomimetic bristle pad 24 is mounted on the fingertip mounting base 23. When the robotic hand performs a grasping action, the magnetorheological biomimetic bristle pad 24 at the fingertip contacts the surface of the object being grasped.

[0073] Specifically, the magnetorheological biomimetic bristle touch pad 24... Figure 3-4 as well as Figure 12-18 As shown. The magnetorheological biomimetic bristle touch pad 24 includes a main pad body 26, which includes three layers: a magnetorheological control layer, a biomimetic adhesive layer and a flexible base layer respectively bonded to both sides of the magnetorheological control layer.

[0074] The magnetorheological control layer has a hollow structure, with an internal cavity filled with magnetorheological fluid 36, forming a magnetorheological fluid cavity 32. The magnetorheological control layer can also have a sandwich structure, with the internal cavity formed by a sandwich space of consistent shape. An injection port 29 is provided on the side wall of the magnetorheological control layer to allow the magnetorheological fluid 36 to be injected into the internal cavity. Alternatively, as... Figure 15-17 As shown, the magnetorheological control layer has a laterally extending main channel 42 at its edge. One end of the main channel 42 extends to the side of the magnetorheological hollow layer, forming an injection port 29. Multiple longitudinally extending branch channels 43 are arranged parallel to each other within the magnetorheological control layer. The cross-sectional area of ​​the main channel 42 is larger than that of the branch channels 43. When magnetorheological fluid is injected into the hollow cavity through the injection port, the fluid flows uniformly from the main channel into each branch channel.

[0075] The magnetorheological control layer is a thin-layer structure formed by injection molding of a flexible polymer, and the thickness of the magnetorheological fluid cavity 32 is between 0.5 mm and 1 mm. The magnetorheological fluid 36 is a carbonyl iron powder-silicone oil-based magnetorheological fluid 36, with an iron powder volume fraction of 20%-40%.

[0076] The biomimetic adhesion layer includes a flexible, sheet-like adhesion layer. An array of protrusions is provided on the first side of the sheet-like adhesion layer, with spacing grooves 40 formed between the protrusions. The protrusions 39 can be rectangular or circular. When the protrusions 39 are rectangular, the spacing grooves 40 form a crisscrossing grid structure. Each protrusion has a through-protrusion and a through-hole 33 in the sheet-like adhesion layer at its center, thus forming a micropore array 27 on the biomimetic adhesion layer. A row of micropores at the ends of the micropore array 27 corresponds to and communicates with the main flow channel, and each row of micropores corresponds to and communicates with a branch flow channel. The second side of the sheet-like adhesion layer, opposite to the first side, is used for sealing and bonding with the side of the magnetorheological control layer. The magnetorheological control layer has connecting channels corresponding to and communicating with each through-hole 33 and the magnetorheological fluid cavity 32. Each protrusion 39 in the protrusion array has biomimetic bristles 28 corresponding to the positions of the through-holes 33, thereby forming bristle tentacles covered with biomimetic bristles 28 on this side surface of the main pad 26. Based on the bristle tentacles, the main pad 26 adheres to the object dryly through van der Waals forces when in contact with the object.

[0077] like Figure 5-10 As shown, the biomimetic bristle 28 has a bristle cavity communicating with the corresponding through-hole 33, and the bristle cavity is filled with magnetorheological fluid 36. The biomimetic bristle 28 can be in the shape of fine hair, and the internal bristle cavity is a fine-pore-shaped cavity. The biomimetic bristle 28 is mushroom-shaped, including a straight bristle body 31 and a mushroom head 30 at the end of the bristle body 31. The mushroom head is hemispherical. The bristle cavity includes a bristle inner cavity 34 inside the bristle body 31 and a head inner cavity 35 inside the mushroom head 30. The bristle inner cavity 34 communicates with the head inner cavity 35 through a connecting port 37 at the end. The mushroom-shaped bionic bristles 28 make contact with the surface of the object being grasped through the mushroom head 30. With the help of the spherical outer surface of the mushroom head 30, they can better adapt to and fit the irregular surface of the object being grasped. This allows each bionic bristle 28 to adaptively deform according to the three-dimensional shape of its contact point and fit with the surface of the object being grasped, ensuring the reliability of the fit.

[0078] The mushroom-shaped outer surface of the cap is arrayed with claw-like spikes 38, each spike being a triangular tip protruding outward from the spherical outer surface. (Combined) Figure 5-8 as well as Figure 11As shown, the claw spikes are arranged in an array as follows: the claw spikes 38 are divided into multiple groups, each group arranged in a semi-circular arc with a certain diameter of the hemispherical mushroom head as the diameter. Multiple groups of claw spikes surround this diameter and are distributed on the outer surface of the spherical shape at intervals with a set central angle. By setting the claw spikes 38, the outer surface of the object being grasped can be more closely adhered to, while enhancing the van der Waals force between the magnetorheological biomimetic bristle pad and the outer surface of the object being grasped. Of course, in other embodiments, the shape of the claw spikes can be other shapes, such as pyramid or cone; the distribution of the claw spikes can also be such that one circle is a group, and multiple groups are distributed in concentric rings with the highest point of the hemispherical mushroom head as the center.

[0079] The bristle 31 is a hollow tubular structure, with its inner hole forming the bristle cavity 34. The thin-shell structure of the mushroom head 30 has its inner cavity forming the head cavity 35, and the shape of the head cavity 35 is consistent with the shape of the mushroom head 30. This ensures that the wall thickness of the mushroom head 30 remains as consistent as possible, guaranteeing good rigidity consistency with the contact surface of the grasped object.

[0080] In the fabrication of the biomimetic adhesive layer, existing micro-nano casting methods (capillary micro-injection molding) and soft etching techniques are used to prepare a biomimetic surface with a nano-mushroom-like array. Polydimethylsiloxane (PDMS) or polyurethane (PU) is selected as the substrate, and a nanopillar array template is fabricated on a silicon wafer using laser interference lithography. A polymer material (often PDMS) is cast into the designed biomimetic surface template. Simultaneously, a solid mold without cavities, representing the millimeter-scale biomimetic surface, is placed into the cast polymer material. The cast composite mold is then placed in a vacuum chamber to remove air bubbles from the biomimetic surface. Next, the cast composite mold is placed in an 80°C vacuum drying oven to accelerate polymer curing. Finally, it is irradiated with ultraviolet light for 24 hours. After the polymer is completely cured, it is peeled off from the composite mold to obtain a biomimetic adhesive layer with mushroom-shaped ends made of a highly elastic polymer material.

[0081] The flexible substrate layer is a flexible silicone or rubber layer with a thickness of millimeters. It is also injection molded and bonded to the side of the control layer of the magnetorheological fluid 36, opposite to the biomimetic adhesion layer, using adhesive. The entire magnetorheological biomimetic bristle pad 24 is bonded to the fingertip mounting base 23 of the grasping finger 14 through the flexible substrate layer.

[0082] Preferably, the diameter of the mushroom head 30 of the manufactured biomimetic bristles 28 is controlled between 200-500 nm, the diameter of the bristle body 31 is controlled between 100-200 nm, the height of the biomimetic bristles 28 is controlled between 1-2 μm, and the array spacing is controlled between 300-600 nm. The iron powder particle size in the magnetorheological fluid 36 is between 5 nm and 10 nm, and the silicone oil is a low-viscosity polyalphaolefin synthetic base oil (i.e., PAO2 oil). The biomimetic bristles 28 have a thin-walled structure so that the diameter of the bristle cavity is above tens of nanometers. Of course, in other embodiments, the size and arrangement of the biomimetic bristles 28 may differ from the ranges listed above, depending on the surface conditions of different objects to be grasped and picked.

[0083] After the main pad 26, which includes the above three-layer structure, is bonded, it is placed in a vacuum chamber and evacuated. Then, it is kept at 80℃-100℃ (at this temperature, the flow viscosity of PAO2 oil is low). Magnetorheological fluid 36 is added to the magnetorheological fluid cavity 32 through the injection hole. Under the action of negative pressure, the magnetorheological fluid 36 can fill the magnetorheological fluid cavity 32 and flow fully into each biomimetic bristle 28. Then, the injection port 29 is sealed to complete the manufacturing of the entire magnetorheological biomimetic bristle touch pad 24.

[0084] An excitation component is embedded within the biomimetic adhesion layer and / or flexible substrate layer, or is covered on the surface of the excitation component. The excitation component has external terminals and is connected to the control module 3 via a power supply line. The control module 3 can control the on / off state and magnitude of the power supply current to the excitation component. The excitation component uses an excitation coil 41, which is a flat electromagnetic coil wound with copper wire. The number of turns is between 50 and 100, and the diameter of the copper wire is 0.2 mm.

[0085] Magnetorheological fluid 36 is a smart material whose rheological properties change drastically under an applied magnetic field. Its apparent viscosity can change from a liquid-like state to a solid-like state within milliseconds, and the transformation process is continuous, reversible, and controllable. Based on the above characteristics of magnetorheological fluid 36, when there is no power supply current to the excitation coil, i.e., when there is no magnetic field at the main pad 26, the magnetorheological fluid 36 exhibits fluid characteristics, and the stiffness of the biomimetic bristles 28 is low. When the control module 3 controls the power supply to the excitation coil, the excitation coil generates a vertical magnetic field at the main pad 26. Under the action of the magnetic field, the magnetorheological fluid 36 transforms into a solid-like state, i.e., hardens, in a very short time, and the stiffness of the biomimetic bristles 28 increases instantaneously. Moreover, by controlling the magnitude of the power supply current to the excitation coil and adjusting the magnitude of the magnetic field, the stiffness of the biomimetic bristles 28 can be adjusted.

[0086] The bottom of the main pad 26 of the magnetorheological biomimetic bristle contact pad 24 is equipped with a force sensor 25 to monitor the normal and tangential forces at the adhesion interface in real time. Specifically, the force sensor 25 is a multi-point distributed flexible thin-film piezoresistive force sensor (such as FSR402), approximately 0.3 mm thick, with a range of 0-10 N and an accuracy of ±0.05 N. The force sensor 25 is embedded inside a millimeter-scale flexible substrate layer. Several force sensors 25 are arranged in an array according to the area of ​​the main pad 26 to detect the force signals at the adhesion interface in the center and edge regions of the main pad 26. The force sensor 25 is connected to the control module 3. After amplification and filtering, the signal from the force sensor 25 is converted into a digital signal by the ADC module and transmitted to the control module 3.

[0087] The grasping hand is equipped with a vision sensor 16 for identifying the object being grasped. The vision sensor 16 is connected to the control module 3 and transmits visual information to the control module 3. Specifically, such as... Figure 1 As shown, the vision sensor 16 is installed at the center of the retraction linkage frame 18, with its lens facing directly in front of the robotic gripper. Positioning the vision sensor 16 at this location allows for a simple and accurate establishment of the positional relationship between the robotic gripper and the grasped object. Based on the visual signal, the relative positional relationship between the grasped object and the robotic gripper can be accurately determined. Of course, in other embodiments, the vision sensor 16 can also be positioned at other locations on the robotic gripper, such as at the end of the gripping arm 10, circumferentially positioned in the gap between two adjacent gripping fingers 14. In one embodiment, the vision sensor 16 uses a miniature CMOS camera with a resolution of 1080P and a standby power consumption of ≤1.5W. Of course, this invention does not preclude the use of other types of vision sensors 16.

[0088] The following description uses a gripping mechanical claw for grasping fruit as an example. The gripping mechanical claw of this invention has three states during use: a stationary state, the grasping process, and the returning process.

[0089] In the static state (initial state): the gripping arm 10 is upright on the rotary seat 7, the gripping fingers 14 are in the open state, and the diameter of the opening formed by each gripping finger 14 is 40mm. The mechanical gripper is at a 45° angle relative to the gripping arm 10.

[0090] Grasping process: The visual sensor 16 detects the location of the fruit to be picked. The control module 3 controls the rotary servo 9 to drive the rotary base 7 to rotate and position the robot arm directly above or below the fruit to be picked. Then, the control module 3 controls the telescopic cylinder 12 to move, driving multiple grasping fingers 14 to open. After that, the control module 3 controls the folding servo 11 and the pitch servo 8 to adjust the vertical distance of the robot arm so that each grasping finger 14 is on the periphery of the fruit to be picked. Then, the control module 3 controls the telescopic cylinder 12 to move, driving multiple grasping fingers 14 to close and clamp the fruit to be picked. The magnetorheological bionic bristle pads 24 of the grasping fingertips 15 of each grasping finger 14 are in contact with the outer surface of the fruit to be picked.

[0091] After the magnetorheological biomimetic bristle pad 24 of the grasping fingertip 15 comes into contact with the outer surface of the fruit being picked, the grasping process is a multimodal adaptive and actively controlled grasping process, specifically: The first is the adaptive flexible fitting mode. Utilizing the softness and high compliance of the biomimetic bristle array 28, it actively conforms to the complex curved surface of the fruit under low stiffness. The biomimetic bristles 28 undergo elastic deformation under slight pressure, increasing the contact area and generating an initial, uniformly distributed adsorption force through van der Waals forces. This stage aims to maximize the contact area and minimize local pressure.

[0092] The second is the critical perception and intelligent decision-making mode. The visual sensor 16 and the force sensor 25 determine that the fruit has been grasped. The force sensor 25, integrated into the bottom of the main pad 26, monitors the total gripping force of the adhesion interface of the bionic bristle array 28 in real time. When the force value reaches the pre-stored safety threshold range based on the fruit's mechanical model in the control module 3 (i.e., the critical force sufficient to grasp and pick the fruit without damaging it), the control module 3 determines that the current state is "optimal fit, critical grip stability".

[0093] Thirdly, there is the stiffness enhancement and stable gripping mode. After the gripping reaches the "optimal fit and critical gripping stability" state, the magnetorheological effect is immediately triggered. That is, the control module 3 supplies power to the excitation coil through the PWM controller. The magnetic field generated by the excitation coil causes the magnetorheological fluid 36 to harden, which increases the stiffness of the adhesion interface, strengthens and maintains the adhesion force, and "freezes" and "locks" the already formed optimal contact form, preventing slippage or stress concentration between the fruit and the mechanical claw. At this time, the gripping force can be effectively transmitted to the harvested fruit through the stiffened adhesion interface, which is sufficient to resist the inertial force and gravity during the harvesting process, while avoiding excessive squeezing and damage to the fruit.

[0094] Fourthly, there is the controllable release mode. After the fruit is picked from the branch, the control module 3 controls the rotation servo 9, pitch servo 8, and folding servo 11 to move the fruit to the designated position. The control module 3 controls the power supply of the excitation component to disconnect and cancel the magnetic field. The magnetorheological fluid 36 in the bionic bristles 28 instantly returns to a liquefied state. The stiffness of the bionic bristles 28 decreases, the adhesion interface becomes soft again, and the adhesion force decreases rapidly, achieving instantaneous "relaxation". At this time, the control module 3 controls the telescopic cylinder 12 to open the mechanical claw, quickly achieving non-destructive detachment of the fruit.

[0095] Furthermore, by embedding a real-time operating system in control module 3, a database of grasping parameters for different fruits (such as apples, peaches, strawberries, tomatoes, grapes, blueberries, kiwis, etc.) is established, including the safe threshold range of adhesion interface force, optimal stiffness curve, finger posture, etc., enabling one-click access. Control module 3 includes a microprocessor, a current drive module, a signal acquisition module, and a communication module, performing tasks such as sensor data acquisition, force control algorithm, current output, and communication processing. The force control algorithm adopts fuzzy PID control, dynamically adjusting the current output value based on the force error and its rate of change at the adhesion interface during the grasping and picking process (i.e., under stiffness enhancement and stable grasping mode), realizing closed-loop control and real-time adjustment of the grasping force. Based on the feedback of the adhesion force, the magnetic field strength of each area is dynamically adjusted to achieve local optimization of the grasping force distribution, compensating for the impact caused by inertial force or gravity during the picking process, ensuring the grasping stability and non-destructive nature throughout the process.

[0096] In one specific embodiment, the microprocessor of the control module 3 is an STM32F407 with a main frequency of 168 MHz, providing sufficient computing power. The current drive module uses an H-bridge circuit with a maximum output current of 2 A, a voltage of 12 V, and a PWM frequency of 1 kHz. The communication module uses a CAN bus or RS485 to exchange data with the main controller of the grasping robot in real time.

[0097] Return process: Control module 3 controls telescopic cylinder 12 and each servo motor to drive the robotic arm back to its initial position for reset calibration.

[0098] The following is a harvesting experiment using the gripping robot of the present invention for fruit picking: Experimental subject: mature tomatoes, about 6-8 cm in diameter, with a surface curvature radius of about 5 cm.

[0099] Grasping Process: ① The robotic arm approaches the tomato, making gentle contact with its biomimetic surface, initially generating an adhesive force of approximately 0.3 N. ② When the force detected by the force sensor 25 rises to 0.8 N (the lower limit of the safe threshold range), it outputs a current of 0.5 A to the excitation coil, causing the viscosity of the magnetorheological fluid 36 to increase and the structural stiffness to increase. ③ The gripping force stabilizes at around 1.2 N (the median of the safe threshold range) for 2 seconds, completing the picking action. ④ The current supplied to the excitation coil returns to zero, and the robotic arm gently detaches, leaving no visible damage to the tomato surface.

[0100] Experimental comparison: Compared with traditional pneumatic grippers, the present invention reduces the gripping damage rate by more than 95%, increases the harvesting success rate to 98%, and improves harvesting efficiency.

[0101] As can be seen from the above introduction, this invention overcomes the limitations of existing gripping manipulators, such as unadjustable stiffness, lack of real-time force feedback, poor adaptability to multiple scenarios, and uncontrollable desorption process, by coupling the controllable rheological properties of magnetorheological fluid 36 with the van der Waals force dry adhesion of the biomimetic bristle microstructure 28. It forms a composite gripping manipulator with real-time adjustable stiffness, self-sensing gripping force, and multi-modal adaptive gripping capabilities.

[0102] Structurally, a three-tiered composite structure of "nano-mushroom-shaped adhesion ends - magnetorheological fluid control layer - millimeter-scale flexible substrate" was designed, achieving synergistic controllability of micro-nano adhesion and macroscopic stiffness. In terms of materials, magnetorheological fluid 36 was embedded for the first time into the biomimetic bristle 28 adhesion structure, and the adhesion interface stiffness was continuously adjusted at the millisecond level by controlling the magnetic field with current. For control, a high-sensitivity mechanical sensor 25 was integrated to construct a closed-loop control system of "sensing-decision-regulation," enabling real-time feedback and adaptive adjustment of the gripping force. Functionally, it possesses multi-modal gripping capabilities of "gentle adsorption - enhanced stiffness - stable gripping - controllable desorption," adaptable to different fruit characteristics and harvesting environments, representing a significant technological advancement.

[0103] As described above, in the above embodiments, the bristle inner cavity extends from the root of the bionic bristle 28 to near the end. This allows for effective control of the stiffness of the entire bionic bristle 28. When the overall stiffness is increased, a conformal support is formed between the side of the main pad 26 and the surface of the grasped object, effectively maintaining the grasping force. When the overall stiffness is decreased, the force is dissipated between the side of the main pad 26 and the surface of the grasped object, facilitating rapid release of the grasped object. Of course, in other embodiments, depending on the surface hardness of the fruit being picked, the bristle inner cavity can extend from the root of the bionic bristle 28 to a position with a certain distance from the end. For example, the bristle inner cavity only includes the bristle inner cavity 34 within the bristle body 31, and the mushroom head 30 is a solid structure, so that the end of the bionic bristle 28 is mainly composed of a highly elastic composite material, unaffected by the rheological properties of the magnetorheological fluid 36, and always contacts the fruit being picked with a relatively soft end.

[0104] In the above embodiments, the side of the sheet-like adhesive layer is provided with an array of protrusions, and the micropores are provided in the middle of each protrusion to form a micropore array 27, with gaps formed between the protrusions. The arrangement of the protrusion array ensures that each biomimetic bristle 28 has its own root stabilization structure, so that when the head of each biomimetic bristle 28 is deformed by compression, the root will not deform significantly. Moreover, due to the arrangement of the gaps, even if the root deforms, it can prevent the deformation of the root of one biomimetic bristle 28 from affecting the roots of adjacent biomimetic bristles 28, ensuring that each biomimetic bristle 28 can adaptively deform based on its contact point with the object being grasped, ensuring a close fit. In other embodiments, the biomimetic bristles 28 can be directly formed on the side of the sheet-like adhesive layer without the protrusion array, which simplifies the structure and reduces manufacturing difficulty.

[0105] In one embodiment, each biomimetic bristle 28 extends perpendicularly to the main pad 26. This structure facilitates etching of the injection mold and reduces manufacturing difficulty and cost. Figure 3-4 In the illustrated embodiment, the bristle bodies 31 of each biomimetic bristle 28 are all tilted towards one side of the main pad 26, and the mushroom heads 30 of each biomimetic bristle 28 protrude outward perpendicular to the side of the main pad 26. This arrangement causes the biomimetic bristles 28 covering the entire bristle pad to form a pad structure oriented to one side. When in contact with the surface of the object being grasped, they deform in the same direction, resulting in good consistency of the grasping force direction. The adaptive flexible fitting mode adhesion force during the grasping process is relatively gentle, and the holding force is relatively stable in the stiffness enhancement and stable grasping mode.

[0106] This invention also provides a specific implementation of the magnetorheological bionic bristle contact pad, the specific structure of which is the same as that of the magnetorheological bionic bristle contact pad included in the gripping manipulator described above, and will not be described again in this article.

[0107] The present invention also provides a specific implementation method for the gripping control method of the gripping robot described above, which is the same as the control method of the gripping process described above.

[0108] The main steps include: 1) Control the robotic arm to retract and grasp the object being grasped. The magnetorheological bionic bristle pads at the tips of the grasping fingers adapt to the surface of the object being grasped and form van der Waals forces. 2) After grasping the object, monitor the force between the bristle pad of the magnetorheological bionic bristle contact pad and the adhesion interface of the object. As the grasping action proceeds, when the force reaches the safe threshold range that can grasp without damaging the object, power the magnetorheological bionic bristle contact pad to harden the magnetorheological fluid, increase the stiffness of the bionic bristles to maintain the grasping state. Then, the grasping arm is controlled to move to perform the picking action. During the picking process, the force between each magnetorheological bionic bristle pad and the adhesion interface of the grasped object is monitored in real time. Fuzzy PID control is used to dynamically adjust the power supply current according to the force error and its rate of change. 3) After picking the fruit off the branch, control the movement of the grasping arm and move the fruit to the designated position. When the fruit needs to be put down, cut off or reduce the power supply to the magnetorheological bionic bristle pad, reduce the stiffness of the bionic bristles, and open the grasping fingers to release and place the grasped object.

[0109] The specific implementation process is as follows: Step S1: Initialize the system and set the safety force threshold range, stiffness adjustment curve, and grasping posture parameters corresponding to the target fruit type.

[0110] Step S2: The vision system locates the fruit, the robotic arm moves to the target position, and the adhesive surface contacts the fruit.

[0111] Step S3: Collect mechanical sensor data in real time and calculate the current gripping force magnitude and distribution.

[0112] Step S4: If the gripping force is lower than the lower limit of the safety threshold, the current is kept at zero to maintain the flexible state of the adhesive structure; if the gripping force enters the safety threshold range, the corresponding current is output according to the force-current mapping relationship pre-stored in the control module (this mapping relationship is obtained based on the pre-grasping implementation for different fruit types) to adjust the stiffness of the bionic bristles.

[0113] Step S5: Continuously monitor the changes in gripping force. If force fluctuations or fruit displacement occur, dynamically adjust the current output through the PID control algorithm to maintain a stable gripping force.

[0114] Step S6: After the picking action is completed, the current returns to zero, the desorption procedure is executed, and the robotic arm is removed.

[0115] In the embodiments described above, step 2) further utilizes fuzzy PID control to dynamically adjust the power supply current in real time. This allows for real-time adjustment of the gripping force during the harvesting process, ensuring the gripping force remains within a safe threshold range while maintaining stable gripping. In other embodiments, depending on the surface hardness of the harvested fruit, if the inertial forces and impacts during harvesting do not damage the fruit surface, the dynamic adjustment process can be omitted. This simplifies the control program and computational load in the control module, reducing costs.

[0116] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. The scope of patent protection of the present invention shall be determined by the claims. Similarly, any equivalent structural changes made based on the description and drawings of the present invention shall also be included within the scope of protection of the present invention.

Claims

1. A magnetorheological biomimetic bristle touch pad, characterized in that, The device includes a main pad containing a magnetorheological fluid cavity. One side surface of the main pad has an array of micropores connected to the magnetorheological fluid cavity. Each micropore has a biomimetic bristle, forming a bristle-like tentacle covered by the biomimetic bristles on that side surface of the main pad. This allows for dry adhesion to an object via van der Waals forces upon contact. Each biomimetic bristle has a bristle cavity that communicates with the corresponding micropore to be filled with the magnetorheological fluid. An excitation component is provided inside or on the surface of the main pad. When the excitation component is energized and magnetized, all the biomimetic bristles harden, thereby achieving shape retention of the bristle tentacle on the object surface.

2. The magnetorheological biomimetic bristle touch pad according to claim 1, characterized in that, The bristle cavity extends from the root of the biomimetic bristle to near the tip.

3. The magnetorheological biomimetic bristle touch pad according to claim 2, characterized in that, The biomimetic bristles are mushroom-shaped, including straight bristle bodies and a mushroom head at the end of the bristle bodies. The bristle cavity includes the bristle body cavity inside the bristle body and the head cavity inside the mushroom head.

4. The magnetorheological biomimetic bristle touch pad according to claim 3, characterized in that, The shape of the inner cavity of the head is consistent with the shape of the mushroom head.

5. The magnetorheological biomimetic bristle touch pad according to claim 3 or 4, characterized in that, Each biomimetic bristle has its bristle body tilted toward one side of the main pad, and the mushroom head of each biomimetic bristle protrudes outward perpendicular to the side of the main pad.

6. The magnetorheological biomimetic bristle touch pad according to any one of claims 1-4, characterized in that, The biomimetic bristles have a thin-walled structure.

7. The magnetorheological biomimetic bristle touch pad according to any one of claims 1-4, characterized in that, The main pad is a flexible pad, and the side of the main pad is provided with an array of protrusions. The micropores are arranged in the middle of each protrusion to form a micropore array, and the protrusions are separated by a gap.

8. The magnetorheological biomimetic bristle touch pad according to any one of claims 1-4, characterized in that, The bottom of the main pad is equipped with a mechanical sensor to monitor the normal and tangential forces at the adhesion interface in real time.

9. The magnetorheological biomimetic bristle touch pad according to claim 8, characterized in that, The main pad includes a magnetorheological control layer and a biomimetic adhesive layer and a flexible base layer respectively bonded to its two sides. The magnetorheological control layer has a hollow structure, and the internal cavity forms the magnetorheological fluid cavity. The biomimetic adhesive layer is provided with the micropore array and connected with biomimetic bristles. The wall surface of the magnetorheological control layer that is bonded to the biomimetic adhesive layer has connecting channels that connect each micropore and the magnetorheological fluid cavity. The flexible base layer is used to connect with the grasping fingers of the robotic arm. The excitation component is a flat excitation coil provided on the biomimetic adhesive layer and / or the flexible base layer to generate a magnetic field perpendicular to the main pad.

10. The magnetorheological biomimetic bristle touch pad according to claim 9, characterized in that, The flexible substrate is a millimeter-scale flexible layer, and the mechanical sensor is a multi-point distributed thin-film force sensor embedded inside the flexible substrate.

11. The magnetorheological biomimetic bristle touch pad according to claim 3 or 4, characterized in that, The diameter of the mushroom head of the biomimetic bristles is between 200-500 nm, the diameter of the bristle body is between 100-200 nm, the height is between 1-2 μm, and the array spacing is between 300-600 nm.

12. A gripping robotic hand, comprising a base, a gripping arm, and a gripping hand, the gripping hand including a gripping palm and a plurality of gripping fingers, characterized in that, At least part of the fingertip of the grasping finger is provided with a magnetorheological bionic bristle touch pad as described in any one of claims 1-11, and a power supply for supplying power to the magnetorheological bionic bristle touch pad and a control module for power supply control are installed on the base or grasping arm.

13. The gripping robot according to claim 12, characterized in that, The mechanical sensor is connected to the control module to transmit the detected force of the adhesion interface to the control module. The control module controls the power supply and the magnitude of the power supply current according to the magnitude of the force.

14. The gripping robot according to claim 12, characterized in that, The grasping hand is equipped with a vision sensor for identifying the object being grasped. The vision sensor is connected to the control module and transmits visual information to the control module.

15. A grasping control method, characterized in that, The gripping robot arm applicable to any one of claims 12-14 includes the following steps: 1) Control the robotic arm to retract and grasp the object being grasped. The van der Waals force is formed by the adhesion between the magnetorheological biomimetic bristle pads at the tips of the grasping fingers and the surface of the object being grasped. 2) After grasping the object, monitor the force between the bristle pad of the magnetorheological bionic bristle contact pad and the adhesion interface of the object. When the force reaches the safe threshold range that can grasp without damaging the object, power the magnetorheological bionic bristle contact pad to harden the magnetorheological fluid and increase the stiffness of the bionic bristles to maintain the grasping state. 3) When it is necessary to put down the grasped object, cut off or reduce the power supply to the magnetorheological bionic bristle pad, reduce the stiffness of the bionic bristles, and open the grasping fingers to release and place the grasped object.

16. The grasping control method according to claim 15, characterized in that, in In step 2), during the process of grasping the object being grasped, the force between each magnetorheological bionic bristle contact pad and the adhesion interface of the object being grasped is monitored in real time. Fuzzy PID control is used to dynamically adjust the power supply current based on the force error and its rate of change.

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