Magnetic control modular variable stiffness soft gripper

Abstract

The application provides a magnetic control modular variable stiffness soft gripper, characterized in that the gripper is composed of a support assembly and a plurality of finger assemblies, the support assembly comprises a mounting chuck and a finger support, and the finger support can be fixedly mounted on the mounting chuck; one finger assembly is composed of a plurality of knuckles in series, and one knuckle comprises an electromagnet, a porous medium elastomer, a magneto-rheological fluid, a silica gel shell, a liquid inlet pipe and a liquid outlet pipe; the porous medium elastomer is in the shape of a curved column, is completely covered by the silica gel shell, and the inner surface of the silica gel shell is tightly combined with the outer surface of the porous medium elastomer; the magneto-rheological fluid is injected into the silica gel shell by using a pump, so that the end of the gripper is deformed in a curved manner; a magnetic field is generated by the electromagnet; the gripper can tightly combine with an object and be solidified; and the whole clamping action is completed through the cooperation of the two. The soft gripper provided by the application has high efficient grasping capacity and can better complete work in various complex environments.

Description

Technical Field

[0001] This invention relates to the field of soft gripper technology, and in particular to a magnetically controlled modular variable stiffness soft gripper. Background Technology

[0002] In manufacturing, companies often use traditional robotic arms or grippers as aids, but they are not adept at using soft materials. Therefore, in recent years, people have been striving to devise new methods to enable robotic arms to grasp small or fragile objects. National Invention Patent CN111571623A discloses a variable stiffness pneumatic soft gripper, designed as a centrally symmetrical three-finger flexible structure. This design utilizes the close fit between the variable stiffness module and the object, along with flexible mechanical clamping force, to grip objects of various complex shapes, solving problems such as enveloping gripping and grasping planar objects.

[0003] The design of the soft gripper is inspired by mollusks. After covering an object, it uses its appendages to grasp and squeeze, much like the tentacles of an octopus, capable of wrapping around (or being wrapped around) different parts of the object to apply pressure. The soft gripper in Chinese invention patent CN111571623A consists of multiple flexible air-conducting tubes that can be filled with air to obtain the necessary pressure to control the object. Because each air-conducting tube is independently pressurized, the tentacles can also form curls in a directional manner, wrapping around and squeezing the object. By increasing sufficient air pressure, the tentacles can gently lift the object, but independent pressure control is relatively complex.

[0004] Current soft grippers have complex structures, mostly relying on pneumatic or hydraulic drives, which are costly and difficult to control when gripping objects. Furthermore, their enveloping gripping effect is not ideal when dealing with irregularly shaped objects. Therefore, a new technical solution is needed to address these issues. Summary of the Invention

[0005] This invention addresses existing technical problems by proposing a magnetically controlled modular variable stiffness soft gripper. A magnetorheological fluid is injected into a silicone shell using a pump, causing the gripper's end to bend and deform. An electronic control system controls the distribution of the magnetic circuit within an electro-permanent magnet, thus magnetizing it and generating a magnetic field. The gripper can then tightly adhere to and solidify against the object. The two work together to complete the clamping action. To achieve the above objective, this invention provides the following technical solution:

[0006] This invention relates to a magnetically controlled modular variable stiffness soft gripper. The gripper is characterized by comprising a support assembly and several finger assemblies. The support assembly includes a mounting chuck and finger supports, wherein the finger supports can be fixed to the mounting chuck. Each finger assembly consists of several phalanges connected in series. Each phalange includes: an electro-permanent magnet, a porous dielectric elastomer, a magnetorheological fluid, a silicone shell, an inlet tube, and an outlet tube. The porous dielectric elastomer is shaped like a curved cylinder. The silicone shell completely encloses the porous dielectric elastomer, with the inner surface of the silicone shell tightly fitted to the outer surface of the porous dielectric elastomer. Two electro-permanent magnets are embedded within the porous dielectric elastomer. The inlet and outlet tubes connect the interior of the silicone shell to the outside environment. The inlet tube can inject the magnetorheological fluid, and the outlet tube can extract the magnetorheological fluid. The magnetorheological fluid exists inside the silicone shell, specifically filling the pores of the porous dielectric elastomer.

[0007] The electro-permanent magnet is made of AlNiCo material, and its internal magnetic circuit distribution is controlled and switched through an electronic control system to achieve the switching between demagnetization and magnetization states. The porous dielectric elastomer is made of an elastic material with an elastic modulus between 25 MPa and 40 MPa, and nanoscale magnetic particles are bonded to the porous dielectric elastomer. The magnetorheological fluid consists of magnetic particles, a base fluid, and a thixotropic agent; the magnetic particles are made of carbonyl iron powder, nickel, or cobalt, and the average particle size is between 1 and 50 μm; the base fluid is made of mineral oil, silicone oil, or fluoroether oil; the thixotropic agent is made of organobentonite, hydrogenated castor oil, or silica to enhance its thixotropic properties. The silicone shell is manufactured using additive manufacturing, such as 3D printing. The thickness of the surface on the side that grips the object is between 2 and 3 mm, the thickness of the surface on the side that does not contact the object is between 5 and 8 mm, and the thickness of the top and bottom sides is between 1 and 2 mm. The elastic modulus of the silicone shell is 2 to 3 times that of the porous media elastomer. The diameter of the inlet and outlet pipes is between 2 and 5 mm, allowing for the injection and extraction of magnetorheological fluid into the cavity using a pump. When magnetorheological fluid is pumped into the knuckles, the rate of change of the porous media elastomer is greater than that of the silicone shell, and because the silicone shell has a relatively smaller top and bottom thickness, it undergoes vertical stretching deformation. Each gripper consists of several finger components, and each finger component is composed of several knuckles connected in series. The number of finger components is X, where X ≥ 2; the number of knuckles on each finger component is Y, where Y ≥ 3. In this gripper, there are two electro-permanent magnets in each segment of the finger assembly. The two electro-permanent magnets can interact to achieve a variable stiffness effect, which hardens the magnetorheological fluid at the joint of the finger or the joint of two finger segments to achieve the gripping effect.

[0008] Compared with existing technologies, the method of this invention has the following advantages: This invention provides a magnetically controlled modular variable stiffness soft gripper. By injecting magnetorheological fluid into the silicone shell using a pump, the gripper's end bends and deforms. A magnetic field is generated by an electro-permanent magnet, allowing the gripper to tightly adhere to and solidify the object. The two work together to complete the entire clamping action. This gripping action has excellent gripping flexibility, can adaptively envelop objects of various shapes, and is not prone to damaging the object's surface. The bending degree of each finger component can be independently controlled, achieving dexterity and multimodality similar to a human hand. Furthermore, due to the excellent physical properties of the magnetorheological fluid, the response is rapid, eliminating the need for sensor installation and allowing it to adapt to complex external environments. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of the initial state of one knuckle of a software gripper.

[0010] Figure 2 This is a schematic diagram showing the distribution of permanent magnets in a soft gripper.

[0011] Figure 3 A schematic diagram showing the changes in a finger joint of a soft gripper before and after fluid is passed through it.

[0012] Figure 4 A schematic diagram of the variable stiffness gripping mechanism for a software-based finger gripper.

[0013] Explanation of key component symbols:

[0014] 1- knuckle, 2- support assembly, 21- mounting chuck, 22- finger support, 11- permanent magnet, 12- porous elastomer, 13- magnetorheological fluid, 14- silicone shell, 15- inlet pipe, 16- outlet pipe. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of this invention clearer, embodiments of the invention are described in detail below, providing further elaboration. It should be understood that the following embodiments are intended to explain the invention but are not intended to limit it.

[0016] like Figure 1As shown, the gripper consists of two finger assemblies fixed to a rigid gripper bracket. Each finger assembly comprises two knuckles connected in series. One knuckle 1 includes: an electro-permanent magnet 11, a porous dielectric elastomer 12, a magnetorheological fluid 13, a silicone shell 14, an inlet pipe 15, and an outlet pipe 16. The porous dielectric elastomer 12 is a curved cylinder. The silicone shell 14 completely covers the porous dielectric elastomer 12, with its inner surface tightly fitted to the outer surface of the porous dielectric elastomer 12. The two electro-permanent magnets 11 are embedded in the porous dielectric elastomer 12. The inlet pipe 15 and the outlet pipe 16 connect the interior of the silicone shell 14 to the outside. The inlet pipe 15 can inject the magnetorheological fluid 13, and the outlet pipe 16 can extract the magnetorheological fluid 13. The magnetorheological fluid 13 exists inside the silicone shell 14, specifically filling the pores of the porous dielectric elastomer 12. The electro-permanent magnet 11 is made of AlNiCo material, and its internal magnetic circuit distribution is controlled and switched by an electronic control system to achieve the switching between demagnetization and magnetization states. The porous dielectric elastomer 12 is made of an elastic material with an elastic modulus between 30 MPa, and nanoscale magnetic particles are bonded to the porous dielectric elastomer 12. The magnetic particles of the magnetorheological fluid 13 are made of carbonyl iron powder, and the average particle size of the magnetic particles is not higher than 50 nm. The base fluid of the magnetorheological fluid is silicone oil, and organic bentonite is added to the magnetorheological fluid 13 to enhance its thixotropic properties. The silicone shell 14 is manufactured by printing. The thickness of the surface on the side that grips the object is 2 mm, the thickness of the surface on the side that does not contact the object is 5 mm, and the thickness of the top and bottom sides is 1 mm. The elastic modulus of the silicone shell 14 is 3 times that of the porous dielectric elastomer 12. The inlet pipe 15 and the outlet pipe 16 have a diameter of 3 mm, and the magnetorheological fluid 13 can be injected and extracted into the cavity using a pump.

[0017] like Figure 2 As shown, the eight electro-permanent magnets are numbered 111 to 118.

[0018] like Figure 3 As shown, when magnetorheological fluid is pumped into the knuckle, the elastic modulus of the silicone shell is three times that of the porous media elastomer. The rate of change of the porous media elastomer is greater than that of the silicone shell. Furthermore, because the thickness of the silicone shell is relatively small, the knuckle undergoes vertical stretching and bending deformation.

[0019] like Figure 4As shown, magnetorheological fluid is injected into the silicone shell using a pump, causing the gripper end to bend and deform. The distribution of the internal magnetic circuit is controlled by an electronic control system, thereby achieving a magnetized state. Two sets of electro-permanent magnets generate a magnetic field, allowing the gripper to tightly adhere to the object. The magnetorheological fluid then solidifies, and the two work together to complete the entire clamping action. When magnetorheological fluid is pumped into the lower section of the finger joint, the finger joint stretches and bends. Under the influence of the magnetic field generated by electro-permanent magnets 113 and 114, and 117 and 118, the stiffness of the lower section of the finger joint increases, allowing the magnetorheological fluid to tightly adhere to the object and solidify, thus achieving the purpose of gripping.

[0020] The embodiments described above are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A magnetically controlled modular variable stiffness soft gripper, characterized in that, The gripper consists of a support assembly (2) and several finger assemblies. The support assembly (2) includes a mounting chuck (21) and a finger support (22), wherein the finger support (22) can be fixedly mounted on the mounting chuck (21). Each finger assembly is composed of several phalanges (1) connected in series. One phalange (1) includes: an electro-permanent magnet (11), a porous dielectric elastomer (12), a magnetorheological fluid (13), a silicone shell (14), an inlet pipe (15), and an outlet pipe (16). The porous dielectric elastomer (12) is in the shape of a curved cylinder, and the silicone shell (13) is... 14) The porous media elastomer (12) is completely covered. The inner surface of the silicone shell (14) is tightly attached to the outer surface of the porous media elastomer (12). Two electro-permanent magnets (11) are embedded in the porous media elastomer (12). The inlet pipe (15) and the outlet pipe (16) connect the inside of the silicone shell (14) to the outside. The inlet pipe (15) can inject magnetorheological fluid (13), and the outlet pipe (16) can extract magnetorheological fluid (13). The magnetorheological fluid (13) exists inside the silicone shell (14) and is specifically filled in the pores of the porous media elastomer (12).

2. The magnetically controlled modular variable stiffness soft gripper according to claim 1, characterized in that, The electro-permanent magnet (11) is made of AlNiCo material. The distribution of its internal magnetic circuit is controlled and converted by an electronic control system, thereby realizing the conversion between demagnetization and magnetization states.

3. The magnetically controlled modular variable stiffness soft gripper according to claim 1, characterized in that, The porous media elastomer (12) is made of an elastic material with an elastic modulus between 25 MPa and 40 MPa, and nanoscale magnetic particles are bonded to the porous media elastomer (12).

4. The magnetically controlled modular variable stiffness soft gripper according to claim 1, characterized in that, The magnetorheological fluid (13) is composed of magnetic particles, a base liquid, and a thixotropic agent; the magnetic particles are made from carbonyl iron powder, nickel, or cobalt, and the average particle size of the magnetic particles is between 1 and 50 μm; the base liquid is made from mineral oil, silicone oil, or fluoroether oil; and the thixotropic agent is made from organic bentonite, hydrogenated castor oil, or silicon dioxide to enhance its thixotropic properties.

5. A magnetically controlled modular variable stiffness soft gripper according to claim 1, characterized in that, The silicone shell (14) is made by additive manufacturing. The thickness of the surface on the side that grips the object is between 2 and 3 mm, the thickness of the surface on the side that does not contact the object is between 5 and 8 mm, and the thickness of the upper and lower sides is between 1 and 2 mm. The elastic modulus of the silicone shell (14) is 2 to 3 times that of the porous media elastomer (12).

6. A magnetically controlled modular variable stiffness soft gripper according to claim 1, characterized in that, The diameter of the inlet pipe (15) and outlet pipe (16) is between 2 and 5 mm, and the magnetorheological fluid (13) can be injected into and extracted into the cavity using a pump.

7. A magnetically controlled modular variable stiffness soft gripper according to claim 1, characterized in that, The gripper is composed of several finger components, and each finger component is composed of several knuckles (1) connected in series. The number of finger components is X, X≥2; the number of knuckles (1) on each finger component is Y, Y≥3.

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