Gripping mechanism and gripping device using a modified magnetic fluid
Patent Information
- Authority / Receiving Office
- DE · DE
- Patent Type
- Patents
- Current Assignee / Owner
- KIQ ROBOTICS INC
- Filing Date
- 2015-03-27
- Publication Date
- 2026-07-30
AI Technical Summary
Conventional magnetic fluids have high relative specific gravities and low viscosities, leading to weak gripping forces, and grippers using jamming phenomena struggle with fluctuating atmospheric pressures and temperature changes.
A modified magnetic fluid is created by mixing nonmagnetic powder, larger in size and lower in specific gravity than ferromagnetic particles, into a magnetic fluid base solution, enhancing gripping force and shear strength.
The modified magnetic fluid achieves lower specific gravity and higher gripping force, allowing stable gripping in varying environments and conditions.
Abstract
Description
Technical field
[0001] The present invention relates to a modified magnetic fluid, which is a further improved version of a magnetic fluid with fine particles of a ferromagnetic body dispersed in a liquid, and also relates to a gripping mechanism and a gripping device that use this modified magnetic fluid. Background technology
[0002] As shown in non-patent literature 1, a magnetorheological fluid (MR fluid) is known, consisting of a gel-like solution in which ferromagnetic ultrafine particles of 10 nm and several μm in size are stably dispersed in a liquid using a surfactant and similar agents. It has been disclosed that this magnetorheological fluid is used for dampers, actuators, seals, and couplings. Patent literature 1 discloses a metallic powder used for a magnetic fluid, formed from an iron-based alloy with a mean particle size of 0.1 to 25 μm and a maximum particle size of 50 μm or less. Patent literature 2 discloses a magnetic fluid composition comprising dispersed magnetic particles with a mean particle size of 0.1 to 500 μm in an ionic fluid containing anions and cations.Patent literature 3 disclosed a structure and a manufacturing process of such magnetic fluid, and patent literature 4 also proposed an article gripping device in which this magnetic fluid is used.
[0003] Regarding the gripping devices (gripping mechanisms) of industrial robots, there are various types depending on the variety of operating processes. Gripping devices used to grasp objects are called grippers, and it is common practice in industrial robot operations to automatically replace one gripper with another suitable for the shape and position of an object. However, this requires complex calculations for the robots to select and replace suitable grippers, create gripping plans for the selected grippers, estimate object positions from the beginning to the end of the gripping process, and similar tasks. This series of operations constitutes a bottleneck for efficient robot operation.Numerous investigations into the forms and mechanisms of gripping organs have been carried out to date, and in recent years, to improve operational efficiency by eliminating methods for determining the orientation of objects to be gripped and for the exchange of grippers, and inventions of a gripping organ (universal jamming gripper, referred to below simply as the “gripper”), such as the one shown in the non-patent literature 2, which freely grips objects of various shapes using negative pressure, have been reported.
[0004] A general description of this gripper 70 is in Fig. 8 shown. The gripper 70 has a holding element 71 , which is to be attached to the tip of a robot arm, a spherical rubber body 72 , which is attached to a lower section of the retaining element 71 to be attached, a fastening ring73 for the removable attachment of the spherical rubber body 72 on the lower section of the retaining element 71 , coffee bean powder 74 , which is inside the spherical rubber body 72 to be recorded, and a vacuum pump (not shown) with outlet openings 75 and 76 of the retaining element 71 to be connected. If this gripper 70 The activities used are to 1) the spherical rubber body 72 to have the shape of an object copied after the spherical rubber body 72 1) against which the object was pressed, 2) releasing air into the interior of the spherical rubber body 72 by activating the vacuum pump and solidifying the spherical rubber body 72 carried out using the jamming phenomenon and 3) actuating the robot arm to lift the object. Reference list of patent literature
[0005] Patent literature 1: Japanese patent no. 5660099 (claims 5 to 9) Patent literature 2: Japanese patent no. 5222296 (claim 1) Patent Literature 3: Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2006-505957 Patent Literature 4: Japanese Unexamined Patent Application Publication No. 2004-154909 Non-patented literature Non-Patent Literature 1: Fujita, Toyohisa and Kunio Shimada “Characteristics and Applications of Magnetorheological Fluids.” Journal of the Magnetics Society of Japan, Volume 27, No. 3, pp. 91-100, 2003 Non-Patent Literature 2: Amend, John R., Jr. Eric Brow,. Nicholas Rodenberg, Heinrich M. Jaeger and Hod Lipson “A Positive Pressure Universal Gripper Based on the Jamming of Granular Material.” IEEE Transactions on Robotics, Volume 28, No. 2, pp. 341–350, April 2012 Summary of the invention: Technical problem
[0006] Since the magnetic fluids described in Non-Patent Literature 1, Patent Literature 1, and Patent Literature 2 use iron powder as fine particles of a ferromagnetic body, there is a problem in that the relative specific gravities of the magnetic fluids become high. Furthermore, there is also a problem in that the viscosities and shear strengths of conventional magnetic fluids alone are relatively low when magnetized. The gripper described in Non-Patent Literature 2 70 It has the advantage of being relatively lightweight and able to easily grasp objects. However, there are problems regarding the gripper's gripping force. 70 is relatively weak, and since the jamming phenomenon that causes the gripping force uses relatively low atmospheric pressures generated by a vacuum generator, it is difficult to control the gripper. 70, to be used when surrounding atmospheric pressures fluctuate, in places under high pressure, such as in water, and in environments where the temperature changes easily, and similar.
[0007] The present invention was made in view of the above circumstances and its objectives are to provide a modified magnetic fluid with a relative specific gravity that is lower than that of conventional magnetic fluids and that has a high gripping force (shear strength) when used for grippers and the like, and to provide a gripping mechanism and a gripping device in which this modified magnetic fluid is used. Solution to the problem
[0008] To solve the preceding problem, a modified magnetic fluid according to a first aspect of the present invention has, at the time it is magnetized, a holding strength which is increased by mixing a non-magnetic powder into a magnetic fluid, wherein the magnetic fluid has a base solution and ferromagnetic fine particles, wherein the ferromagnetic fine particles are present in a dispersed state in the base solution, and wherein the non-magnetic powder has a larger size and a lower specific gravity than the ferromagnetic fine particles.
[0009] In the case of the modified magnetic fluid according to the first aspect, it is preferred that the non-magnetic powder consists of a glass, plastic, or ceramic powder. Furthermore, in the case of the modified magnetic fluid according to the first aspect, it is preferred that the non-magnetic powder consists of a plastic foam. The non-magnetic powder obviously does not dissolve in or react with the base solution of the magnetic fluid. It is also preferred that the non-magnetic powder has a specific gravity lower than that of the base solution (e.g., γ = 0.3 to 0.8) and that the non-magnetic powder is spherical.
[0010] In the case of the modified magnetic fluid according to the first aspect, it is preferred that the particle size of the non-magnetic powder is 2 mm or less. Furthermore, in the case of the modified magnetic fluid according to the first aspect, it is preferred that the proportion of the magnetic fluid in the modified magnetic fluid is in the range of 40 to 80%. An MR fluid can also be used as the magnetic fluid.
[0011] A gripping mechanism according to a second aspect of the present invention uses the modified magnetic fluid described above according to the first aspect and has a flexible bag in which the modified magnetic fluid is contained and an electromagnet arranged on one side of the bag and capable of magnetizing the modified fluid in the bag.
[0012] In the case of the gripping mechanism according to the second aspect, it is preferred that the electromagnet has a magnetic pole section in a center of the electromagnet, a cylindrical yoke section with a bottom that surrounds the magnetic pole section, and a coil wound around the magnetic pole section, and that the bag filled with the modified magnetic fluid is attached in a closed state to an open end of the yoke section.
[0013] In the case of the gripping mechanism according to the second aspect, it is preferred that the modified magnetic fluid fills the bag by 40 to 70%. Furthermore, in the case of the gripping mechanism according to the second aspect, it is preferred that the bag has a hemispherical shape with a flange.
[0014] A gripping mechanism according to a third aspect of the present invention has the gripping mechanism described above according to the second aspect, which is attached to a tip end of a robot arm. Furthermore, a gripping device according to a fourth aspect of the present invention has the gripping mechanism described above according to the second aspect, which is provided on each of the holding sections of a robot such that they are opposite to each other, the holding sections having a controlled distance between them. Advantageous results of the invention
[0015] Since, in the case of the modified magnetic fluid, the non-magnetic powder, which is larger and has a lower specific gravity than the ferromagnetic fine particles, is mixed into the conventional magnetic fluid according to the first aspect, the overall specific gravity becomes lower than that of the conventional magnetic fluid. When this modified magnetic fluid is magnetized, the large non-magnetic powder acts as an aggregate, which improves the holding power and shear strength of the modified magnetic fluid at the time of magnetization.
[0016] If, in the case of the modified magnetic fluid, the non-magnetic powder is made of glass, plastic, or ceramic material, as described in the first aspect, its density will be even lower, and a uniformly granulated non-magnetic powder can be easily obtained, resulting in more balanced physical properties of the modified magnetic fluid. If the non-magnetic powder is spherical or made of plastic foam, the specific gravity of the modified fluid will also decrease, and its physical properties will be balanced.
[0017] Since the gripping mechanism, according to the second aspect, uses the modified magnetic fluid described above according to the first aspect and has the flexible bag in which the modified magnetic fluid is contained, and the electromagnet is arranged on one side of the bag and is capable of magnetizing the modified magnetic fluid in the bag, the bag can grip part or all of the object while maintaining a shape of the object.
[0018] If, particularly in the case of the gripping mechanism according to the second aspect, the fill level of the modified magnetic fluid in the bag is made to 40 to 70%, there are cavities and bulges on a surface of the bag, which makes it easy to fit objects into the bag and allows the gripping of any objects whose sizes lie within a certain range.
[0019] Furthermore, since the gripping device according to the third aspect has the gripping mechanism described above according to the second aspect, which is attached to the tip side of the robot arm, the gripping mechanism can be moved freely, and the position of the gripping mechanism can be changed at the same time. Brief description of the drawings
[0020] Fig. 1(A) is a perspective view of a gripping mechanism according to an embodiment of the present invention; and Fig. 1(B) is a main cross-sectional view of the same gripping mechanism.
[0021] Fig. 2(A) is a perspective view of an electromagnet of the same gripping mechanism and Fig. 2(B) is a cross-sectional view of the electromagnet of the same gripping mechanism.
[0022] Fig. Figure 3 is a perspective view of a gripping device in which the same gripping mechanism is attached to a robot arm of a multi-jointed robot.
[0023] Fig. Figure 4(A) is a diagram showing a relationship between the proportion of a magnetic fluid (MR fluid) in a modified magnetic fluid and the gripping force; and Fig. Figure 4(B) is a diagram showing a relationship between the particle size of a non-magnetic powder and the holding force.
[0024] Fig. Figure 5(A) is an explanatory diagram for the behavior of the modified magnetic fluid; and Fig. Figure 5(B) is an explanatory diagram for the behavior of a magnetic fluid according to a conventional example.
[0025] Fig. Figure 6 is a diagram showing a relationship between the types and sizes of non-magnetic powders and the holding force.
[0026] Fig. Figure 7 is a perspective view of another gripping device in which the same gripping mechanism and another gripping mechanism that is the same as the gripping mechanism are arranged opposite each other.
[0027] Fig. Figure 8 is a cross-sectional view of a gripping mechanism (gripper) according to a conventional example. Description of embodiments
[0028] Next, with reference to the accompanying drawings, a description of an embodiment of the present invention will be given. As shown in Fig. 1(A) and Fig. 1(B) shows a gripping mechanism 10 according to one embodiment of the present invention, a flexible bag 12 , in which a modified magnetic fluid 11 is recorded, and an electromagnet 13 , located on one side (in this embodiment on a top side) of the bag 12is arranged and the modified magnetic fluid 11 in the bag 12 magnetized.
[0029] The electromagnet 13 has, as in Fig. 2(A) and Fig. 2(B) shows a magnetic pole section 15 , which is located in the center of the electromagnet 13 is arranged and made of a magnetic material, a yoke section 16 , which is the magnetic pole section 15 surrounds and is made of a cylindrical magnetic material with a bottom surface, a coil 17 , which surround the magnetic pole section 15 is wrapped around it, and a magnetic pole plate section 15a , which is located at an open end of the magnetic pole section 15 is provided and has a diameter larger than that of the magnetic pole section. 15 is. The bag 12It is made of an oil-resistant, non-magnetic, and flexible rubber or plastic layer, such as silicone rubber, and has a hemispherical section. 18 and a flange section 19 , the integral at one end of the hemispherical section 18 is provided, which is a hemispherical layer with a flange. It is preferred that the diameter D of the hemispherical section 18 approximately 30 to 80 mm. However, since the preferred diameter D varies depending on the objects to be gripped, the present invention is not limited to these numerical values. A thickness of the bag 12 For example, it is approximately 0.3 to 2 mm.
[0030] The bag 12 is by means of first and second fastening elements 22 and 23 , which includes the flange section 19 Hold it in between, at a lower section of the electromagnet 13provided. That is, the first fastening element. 22 will be attached to a lower end of the yoke section 16 screwed, and the first fastening element 22 and the second fastening element 23 are through the flange section 19 through several bolts 24 connected to each other. The bag 12 This results in a closed state at an open end of the yoke section. 16 attached.
[0031] In the bag 12 is the modified magnetic fluid 11 according to one embodiment of the present invention. A quantity of the modified magnetic fluid 11 The amount to be recorded (fill rate) lies within the range of 40 to 70% of a state in which the hemispherical section 18 with a radius R of the bag 12 is completely inflated (volume V = 2πR) 3 / 3). If the amount of modified magnetic fluid 11 The total amount of modified magnetic fluid is smaller than this area. 11 insufficient, and if the amount of modified magnetic fluid 11 Beyond this area, the bag's reach will be defined. 12 small, however, the amount of modified magnetic fluid can 11 Depending on the intended use, this area may be exceeded.
[0032] The modified magnetic fluid 11The magnetic material is produced by mixing a non-magnetic powder into a normal magnetic fluid containing ferromagnetic fine particles in a dispersed state within a base solution. The normal magnetic fluid, as previously described, is a magnetic gelatinous solution consisting of ferromagnetic fine particles, such as magnetite and manganese zinc ferrite, a surfactant coating the surfaces of the ferromagnetic fine particles, and a base solution (e.g., water, isoparaffin, alkylnaphthalene, or another type of oil). The diameters of the ferromagnetic fine particles are approximately 10 nm, ranging from 10 nm to 200 μm, and preferably from approximately 100 to 200 μm. In this embodiment, the non-magnetic powder consists of particles made from a polystyrene foam, an example of a plastic foam that has a larger size and lower specific gravity than the ferromagnetic fine particles.
[0033] Fig. 4(A) represents the holding force of the bag 12 in the case where a volume fraction between the magnetic fluid (an MR fluid was used) and the non-magnetic powder was changed, and Fig. 4(B) establishes a relationship between the size of the non-magnetic powder and the gripping force of the bag. 12 This is the case where the ratio of magnetic fluid to non-magnetic powder is 1:1. Here, the volume of the non-magnetic powder is an apparent volume. It is made up of Fig. 4(A) to recognize that the holding force of the modified magnetic fluid is high when the proportion of the magnetic fluid in the modified magnetic fluid is in the range of 40 to 80%. Furthermore, it is evident from Fig. 4(B) to recognize that the modified magnetic fluid has a high holding force when the particle size of the non-magnetic powder is 2 mm or less. As from Fig. As can be seen in Figure 4(B), the holding force reaches its maximum value when the particle size of the non-magnetic powder is 0.5 mm. However, it can be considered that if the particle size of a non-magnetic powder is larger than that of ferromagnetic fine particles (e.g., five times or more, i.e., 50 nm or larger), the modified magnetic fluid exerts a sufficient holding force.
[0034] Fig. 5(A) represents a non-magnetic field state and a magnetic field state using the modified magnetic fluid 11 This represents a magnetic fluid in the non-magnetic field state. 27 (a mixed fluid consisting of a base solution and the ferromagnetic fine particles 25 ) and a non-magnetic powder 26 freely mixed. However, the ferromagnetic fine particles bind together. 25 in the magnetic field state together and the non-magnetic powder 26It acts as an aggregate, and it can be considered that the holding strength and the shear strength of the modified magnetic fluid 11 thereby increase the height.
[0035] For comparison, in Fig. 5(B) Behavior in the non-magnetic field state and the magnetic field state using the conventional magnetic fluid 27 The diagram shows that the ferromagnetic fine particles move in the non-magnetic field state. 25 free, and in the magnetic field state the ferromagnetic particles bind together. 25 together; however, since there is nothing that acts other than the aggregates, it can be concluded that a gripping strength and a shear force of the magnetic fluid 27 are not high. Fig. 5(A) and Fig. 5(B) are schematic diagrams for explanation, and densities of the ferromagnetic particles 25 and the non-magnetic powder 26are higher in reality.
[0036] Fig. Figure 6 represents gripping forces in the case where the types and sizes of the non-magnetic powders used in a modified magnetic fluid (MR fluid) have been changed. Nicabeads (brand name, carbon microbeads) with a diameter of 0.0221 mm exhibit a high holding force; however, polystyrene foam with a diameter of 0.5 mm also shows sufficient gripping force.
[0037] Fig. 3 represents a gripping device 30 for which the gripping mechanism described above 10 is used. The gripping mechanism 10 is on one end of a robot arm 32 a multi-jointed robot 31 attached. The gripping mechanism 10 This allows it to be freely moved to specific positions and different angles in order to grasp an object. That is to say, the bag 12 the gripping mechanism 10is placed over the object, part or all of the object is placed in a depression in the bag 12 fitted, the electromagnet 13 It is then powered with energy and the modified magnetic fluid 11 is magnetized. It is preferred that the electromagnet 13 A magnet is defined as one that is strong enough not to magnetically saturate the fine ferromagnetic particles (e.g., 0.05 to 0.3 T). However, depending on the intended application, magnetic fields ranging from weak to strong are applicable.
[0038] Since the modified magnetic fluid 11 While maintaining a gripping state, objects can be moved by the robot arm 3 The object can be moved. After moving an object to a predetermined position, the object can be removed by stopping the energy supply to the electromagnet. 13 and loosening the shape of the bag 12 to be arranged at the specified position.
[0039] Fig. 7 represents a gripping device 36 depicting the gripping mechanism 10 at each of the stopping sections 34 and 35 a robot is attached so that they are opposite each other, with the holding sections 34 and 35 They have a gap between them that can be changed using a motor, hydraulic cylinder, or similar device. This is achieved by inserting an object from both sides using the bags. 12 the two gripping mechanisms 10 and energy supplies for the electromagnets 13 Can the object be moved between the opposing gripping mechanisms? 10 be held. In Fig. 7 shows the number 37 a mounting flange for attaching the gripping device 36 on an arm and similar part of the robot, the number 38 displays a case and the number 39 indicates an operating handle.
[0040] The present invention is not limited to the foregoing embodiment, and the structures can be modified within the scope of what is necessary to establish the spirit of the present invention. For example, in the foregoing embodiment, polystyrene foam was used as the non-magnetic powder; however, other types of powder made of plastic foam, non-expanded plastics, glass, ceramics (more precisely, aggregate particles), carbon particles, and the like can be used as the non-magnetic powder. Furthermore, the shapes of the electromagnet and the bag can also be freely modified depending on the intended use. Industrial applicability
[0041] The modified magnetic fluid according to the present invention can be used, in addition to the gripping mechanism mentioned above, for magnetic fluid seals (rotary shaft seals), dampers, loudspeakers, sensors, separation by difference in specific gravity, and the like. Furthermore, the gripping mechanism and gripping device can be used for carrier machines, actuators, and similar devices in specific locations. Reference symbol list 10 : Gripping mechanism, 11 : modified magnetic fluid, 12 : bag, 13 : Electromagnet, 15 : Magnetic pole section, 15a : Magnetic pole plate section, 16 : Yoke section, 17 : coil, 18 : hemispherical section, 19 : Flange section, 22 : first fastening element, 23 : second fastening element, 24 : bolts, 25 : ferromagnetic fine particles, 26: non-magnetic powder 27 , magnetic fluid, 30 : Gripping device, 31 : Multi-joint device, 32 : robot arm, 34 , 35 : Stopping section, 36 : Gripping device, 37 : Mounting flange, 38 : Housing, 39 : Operating handle
Claims
[1] Modified magnetic fluid that exhibits: a holding strength at the time it is magnetized, which is increased by mixing a non-magnetic powder into a magnetic fluid, wherein the magnetic fluid has a base solution and ferromagnetic fine particles, wherein the ferromagnetic fine particles are present in a distributed state in the base solution, and wherein the non-magnetic powder has a larger size and a lower specific gravity than the ferromagnetic fine particles. [2] Modified magnetic fluid according to claim 1, wherein the non-magnetic powder consists of a glass, plastic or ceramic powder. [3] Modified magnetic fluid according to claim 1, wherein the non-magnetic powder consists of a plastic foam. [4] Modified magnetic fluid according to any one of claims 1 to 3, wherein the particle size of the non-magnetic powder is 2 mm or less. [5] Modified magnetic fluid according to any one of claims 1 to 4, wherein a proportion of the magnetic fluid in the modified magnetic fluid is in the range of 40 to 80%. [6] Modified magnetic fluid according to any one of claims 1 to 5, wherein the magnetic fluid is an MR fluid. [7] Gripping mechanism which uses the modified magnetic fluid according to any one of claims 1 to 6, comprising: a flexible bag containing the modified magnetic fluid, and an electromagnet that is located on one side of the bag and is capable of magnetizing the modified fluid in the bag. [8] Gripping mechanism according to claim 7, wherein the electromagnet has a magnetic pole section in a center of the electromagnet, a cylindrical yoke section with a bottom surface surrounding the magnetic pole section, and a coil wound around the magnetic pole section, and the bag filled with the modified magnetic fluid is attached in a closed state to an open end of the yoke section. [9] Gripping mechanism according to claim 8, wherein the fill content of the modified magnetic fluid in the bag is 40 to 70%. [10] Gripping mechanism according to one of claims 7 to 9, wherein the bag has a hemispherical shape with a flange. [11] Gripping device comprising: the gripping mechanism according to one of claims 7 to 10, which is attached to a tip side of a robot arm. [12] Gripping device comprising: the gripping mechanism according to one of claims 7 to 10, which is provided on each of the holding sections of a robot such that they are opposite to each other, wherein the holding sections have a distance between them which can be controlled.