Clilium type magnetic tactile perception method for concentrated force load

Abstract

The invention discloses a cilia type magnetic tactile perception method for concentrated force load. The size and direction of the concentrated force load are calculated based on magnetic field distribution around magnetic cilia by using a force-magnetic coupling model; the magnetic cilia is composed of a flexible non-magnetic material segment and a flexible magnetic material segment, the flexible non-magnetic material end is fixed to the substrate, and the flexible magnetic material end is a free end; discretizing the magnetic cilia into a plurality of sections, wherein each section is regarded as a magnetic dipole fragment; the overall space magnetic field distribution of the magnetic cilia is obtained by superposing the magnetic fields of all the magnetic dipole segments based on the superposing performance of the magnetic fields. The method has the advantages of high sensitivity, simple structure, strong anti-interference capability and the like, and is suitable for the fields of robot touch, medical micro-force detection, industrial precision measurement and the like.

Description

Technical Field

[0001] The present invention relates to the field of tactile perception technology, and in particular to a ciliary magnetic tactile perception method for concentrated force loads. Background Art

[0002] The rapid development of robotics technology has placed higher demands on the environmental perception capabilities of robotic systems. Among various perception modalities, tactile perception plays a key role in simulating the sensitive response of human skin to external contact stimuli.

[0003] Tactile sensors enable robots to acquire a variety of contact-related information, including pressure, shear force, vibration, and surface roughness. They are widely used in cutting-edge fields such as robotic precision manipulation, biomimetic electronic skin development, and tactile feedback for intelligent prosthetics. To meet the diverse needs of these applications, tactile sensors based on different operating principles have been developed. Among them, those based on magnetic sensing mechanisms have become a particularly promising technical solution due to their high sensitivity, flexible structural design, ease of integration, and remote readability.

[0004] In nature, many organisms use cilia-like structures to achieve highly sensitive environmental perception. Inspired by this, researchers have incorporated cilia into tactile sensor design to improve the resolution and responsiveness to subtle tactile stimuli.

[0005] With the rapid development of magnetic sensing technology, especially the advancement of high-sensitivity magnetic levitation equipment and magnetic flux detection technology, it has become possible to construct artificial magnetic cilia with magnetic response characteristics. The deformation of cilia caused by external force or fluid flow will cause changes in the magnetic field. By detecting these changes, a high-sensitivity response to complex tactile stimuli can be achieved. For example: Patent specification with publication number CN119555330A discloses an aircraft flow field sensing device and method based on magnetic cilia; Patent specification with publication number CN117268596A discloses a method for obtaining the magnitude and direction of shear force based on a flexible magnetized cilia film. This method first obtains the change in the spatial magnetic field signal caused by the change in cilia displacement on the flexible magnetized cilia film after the shear force is applied; and then obtains the magnitude and direction of the applied shear force based on the change in the spatial magnetic field signal.

[0006] Current research on magnetic tactile sensors relies primarily on extensive experimental calibration and qualitative phenomenological analysis, with limited efforts to guide the design and fabrication of magnetic tactile fibers through quantitative theoretical models. Existing simulation tools also struggle to accurately simulate the behavioral characteristics of deformable magnetic structures. This empirical approach limits the predictability and design optimization potential of magnetic tactile sensors based on fibers.

[0007] Conventional tactile sensors currently suffer from insufficient sensitivity and complex structures when detecting concentrated force loads. While magnetic tactile sensors offer unique advantages, they still face challenges in detecting concentrated force. For one thing, existing magnetic sensing solutions struggle to accurately analyze the quantitative relationship between ciliary deformation and magnetic field distribution. Furthermore, they lack effective force-magnetic coupling models to infer the magnitude of external force. These technical bottlenecks hinder the application of magnetic tactile sensors in advanced applications such as robotic precision manipulation and minimally invasive surgery. Summary of the Invention

[0008] To address the aforementioned technical issues and shortcomings in the field, the present invention provides a ciliary magnetic tactile sensing method for concentrated force loads. Based on the phenomenon that the bending and deformation of magnetic cilia induce changes in the spatial magnetic field, the method detects the magnetic field distribution and calculates the magnitude and direction of the concentrated force load using a force-magnetic coupling model. This method offers advantages such as high sensitivity, simple structure, and strong anti-interference capabilities. It is suitable for applications in robotic tactile sensing, medical micro-force detection, and industrial precision measurement.

[0009] A ciliary magnetic tactile sensing method for concentrated force loads, which uses a force-magnetic coupling model to calculate the magnitude and direction of the concentrated force load based on the magnetic field distribution around the magnetic ciliary hairs;

[0010] The magnetic cilia are composed of a flexible non-magnetic material segment and a flexible magnetic material segment, wherein the flexible non-magnetic material end is fixed to the base and the flexible magnetic material end is a free end;

[0011] The magnetic cilia are discretized into several segments, each of which is regarded as a magnetic dipole segment. For a magnetic dipole segment at any position z, the force-magnetic coupling model is as follows:

[0012]

[0013] in:

[0014] z is the coordinate along the axis of the magnetic cilia when there is no concentrated load, x and y are the coordinates of two axes perpendicular to each other in the plane perpendicular to the z axis, dB x 、dB y 、dB z are the magnetic field intensity components of the magnetic dipole segment in the x-axis, y-axis, and z-axis directions, μ0 is the vacuum magnetic permeability, R is the radius of the magnetic cilia, M is the magnetization intensity, a=|a| is the distance from the magnetic field observation point to the magnetic dipole segment, a is the position vector of the magnetic field observation point relative to the magnetic dipole segment, θ = θ(z) is the rotation angle of the magnetic cilia at position z, is the angle between the direction of concentrated force load application and the x-axis, (x0, y0, z0) are the coordinates of the magnetic field observation point, and w(z) is the deflection of the magnetic cilia at position z;

[0015] The spatial magnetic field distribution of the entire magnetic cilium is obtained by superimposing the magnetic fields of all magnetic dipole segments based on the superposition of magnetic fields.

[0016] Preferably, the spatial magnetic field distribution of the entire magnetic cilia in the x-axis, y-axis, and z-axis directions is calculated by the following formula:

[0017]

[0018] Wherein, z1 represents the length of the flexible non-magnetic material segment in the z-axis direction, and z2 represents the length of the entire magnetic cilium in the z-axis direction.

[0019] When a concentrated force load is applied to the free end of the magnetic cilia, the magnetic cilia will bend and deform. The idea of ​​constructing the force-magnetic coupling model in the present invention is as follows:

[0020] Based on the cantilever beam differential equation, the deflection distribution of the magnetic cilia is calculated;

[0021] The magnetic cilia bent by concentrated force are discretized into several segments, each of which is regarded as a magnetic dipole segment.

[0022] Based on the deflection distribution, the spatial position and orientation of each magnetic dipole segment are determined;

[0023] Calculate the magnetic field distribution in space for each magnetic dipole segment.

[0024] The construction process of the force-magnetic coupling model of the present invention is specifically described as follows:

[0025] Considering the magnetic cilium as a cantilever beam, its differential equation is:

[0026]

[0027] Where: E is the elastic modulus E1 of the flexible non-magnetic material or the elastic modulus E2 of the flexible magnetic material, I is the moment of inertia of the section, I = πd 4 / 64, d = 2R is the diameter of the magnetic cilia, M(z) is the bending moment caused by the concentrated load, and the expression is as follows:

[0028]

[0029] See also Figure 1 , F is the concentrated force load, and h is the distance between the application position of the concentrated force load and the fixed end of the magnetic cilia in the z-axis direction.

[0030] In the present invention, z1 and z2 can be determined by the following equations:

[0031]

[0032] in:

[0033] θ2 is the rotation angle of the position where the concentrated force load is applied (i.e., the distance h from the fixed end of the magnetic cilia in the z-axis direction), θ1 is the rotation angle of the top position of the flexible non-magnetic material segment (i.e., the distance z1 from the fixed end of the magnetic cilia in the z-axis direction), L1 is the initial length of the flexible non-magnetic material segment in the z-axis direction, and L2 is the initial length of the flexible magnetic material segment in the z-axis direction, as shown in Figure 2. Figure 1 shown.

[0034] Solving the differential equation, we can get the solution of the deflection distribution of the magnetic cilia in the z-axis direction:

[0035]

[0036] The magnetic cilia bent by the concentrated force load are regarded as a series of magnetic dipole segments connected end to end. The magnetic field distribution dB of the magnetic dipole segments is calculated by the following formula:

[0037]

[0038] Where m is the magnetic dipole moment.

[0039] In the present invention, a and m·a can be expressed as follows:

[0040]

[0041] in: is the unit vector in the x-axis direction, is the unit vector in the y-axis direction, is the unit vector in the z-axis direction.

[0042] Substituting the above expressions of a and m·a into the calculation formula of the magnetic field distribution dB of the above magnetic dipole segment and decomposing it into components, the force-magnetic coupling model is obtained.

[0043] Preferably, in the ciliary magnetic tactile sensing method for concentrated force load, when there is no concentrated force load, the magnetization direction of the magnetic ciliary hair is the axial direction of the magnetic ciliary hair.

[0044] Preferably, in the ciliary magnetic tactile sensing method for concentrated force load, the magnetic cilia are slender structures with cylindrical or rectangular cross-sections, with a length of 1 to 50 mm and a diameter of 0.1 to 10 mm.

[0045] Preferably, in the ciliary magnetic tactile sensing method for concentrated force load, the Young's modulus of the flexible magnetic material segment is greater than the Young's modulus of the flexible non-magnetic material segment.

[0046] Preferably, in the ciliary magnetic tactile sensing method for concentrated force load, the flexible non-magnetic material segment is a flexible polymer, such as polydimethylsiloxane (PDMS), silicone rubber (such as Ecoflex 00-30, etc.), polyurethane, etc.

[0047] Preferably, in the ciliary magnetic tactile sensing method for concentrated force loads, the flexible magnetic material segment is prepared by compounding hard magnetic powder (such as aluminum nickel cobalt alloy, neodymium iron boron permanent magnet material, samarium cobalt permanent magnet material, permanent ferrite, etc.) with a flexible polymer matrix (such as PDMS, silicone rubber, polyurethane, etc.). Further preferably, the mass proportion of the hard magnetic powder in the flexible magnetic material segment is 40% to 60%, such as 50%. The particle size of the hard magnetic powder is preferably 3 to 10 μm, such as 5 μm.

[0048] Preferably, the ciliary magnetic tactile sensing method for concentrated force loads detects the magnetic field distribution around the magnetic ciliary hairs using a magnetic field sensor. Further preferably, the magnetic field sensor is a (three-axis) Hall sensor, a magnetoresistive sensor, or a fluxgate sensor. The Hall sensor can specifically be an MLX90393 three-dimensional Hall sensor, comprising an MLX90393 chip body, a PCB board, and pin headers. The magnetic field sensor can be disposed at the bottom of the substrate.

[0049] Preferably, in the ciliary magnetic tactile sensing method for concentrated force load, the substrate is a flexible or rigid material, including silicone, PDMS or glass.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] 1. High sensitivity: A slight deformation of the magnetic cilia can cause significant changes in the magnetic field;

[0052] 2. Simple structure and low cost: no complex circuits or optical components are required;

[0053] 3. Strong anti-interference ability: Magnetic field detection is less affected by factors such as ambient light and temperature;

[0054] 4. Wide range of applications: By adjusting the parameters of magnetic cilia, it can be used in many fields such as robot touch, medical micro-force detection and industrial precision measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 This is a schematic diagram of the meanings of some variables in the formula involved in the present invention.

[0056] Figure 2 This is a schematic diagram of the result after casting and curing of the first section of the split mold in a specific implementation method.

[0057] Figure 3This is a schematic diagram of the result after casting and curing of the second section of the split mold in a specific implementation method.

[0058] Figure 4 This is a schematic diagram of the morphology of magnetic cilia after demolding in a specific embodiment.

[0059] Figure 5 Schematic diagram of the structure in which the magnetic cilia are vertically adhered to an 18 mm×18 mm cover glass through a mold in a specific embodiment.

[0060] Figure 6 This is a schematic diagram of the structure in which magnetic hairs are attached to the sensor base in a specific embodiment.

[0061] Figure 7 Graph showing the relationship between the calculated magnetic field variation and the magnitude of the concentrated force in a specific implementation manner.

[0062] Figure 8 3 is a comparison chart of experimental results and theoretical values ​​in a specific implementation manner. DETAILED DESCRIPTION

[0063] The present invention will be further described below in conjunction with the accompanying drawings and specific examples. It should be understood that these examples are intended to illustrate the present invention and are not intended to limit the scope of the invention. The operating methods in the following examples where no specific conditions are specified are generally performed under conventional conditions or as recommended by the manufacturer.

[0064] The present invention realizes the reverse calculation of concentrated force load through the following process:

[0065] (1) Solve the mathematical model of magnetic field distribution and concentrated force load under existing parameters to obtain the relationship between the change of magnetic field and the magnitude and direction of concentrated force;

[0066] (2) The magnitude and direction of the concentrated force load can be inferred from the detected magnetic field data.

[0067] 1. Production of magnetic cilia:

[0068] The split mold is made using additive manufacturing.

[0069] According to the material quality ratio SE 1700 (Dow DOW silicone adhesive DOWSI TM After the mixture was prepared, the mixture was mixed at a speed of 2000 revolutions per minute using a mixer (Thinky, AR100) for 1 minute, and then degassed at the same speed for 1 minute to obtain a flexible non-magnetic material.

[0070] like Figure 2As shown, the flexible non-magnetic material is poured onto the first section of the split mold and vacuum degassing is performed to allow the flexible non-magnetic material to completely fill the pores of the mold. Then, they are placed together in a constant temperature oven at 120°C for curing for 2 hours. After curing, the excess material is removed with a tool, and the other two sections of the split mold are installed on the first section for standby use.

[0071] According to the material quality ratio SE 1700 (Dow DOW silicone adhesive DOWSI TM SE 1700, 45.45%), SE1700 supporting catalyst (4.55%) and 5 μm diameter NdFeB particles (50%) were mixed in a mixer (Thinky, AR100) at a speed of 2000 revolutions per minute for 1 minute, and then degassed at the same speed for 1 minute to obtain a flexible magnetic material.

[0072] like Figure 3 As shown, the ciliary flexible magnetic material is poured onto a three-section assembled split mold, and vacuum degassing is performed to allow the flexible magnetic material to completely fill the pores of the mold. Then, they are placed together in a constant temperature oven at 120°C for curing for 2 hours. After curing, the excess material is removed with a tool, and the finished magnetic ciliary material is demoulded to obtain the finished product, as shown. Figure 4 As shown, the magnetic cilia are a two-section vertical structure, wherein the lower part is a flexible non-magnetic material segment, and the upper part is a flexible magnetic material segment. The magnetization direction of the magnetic cilia is vertically upward.

[0073] Install the MLX90393 magnetic sensor into the housing and stick a 24mm×24mm large cover glass on it as a reference surface. Figure 5 As shown in the figure, the magnetic cilia are glued to a small cover glass of 18mm×18mm using Jule-460 quick-drying glue, and a mold is used to ensure that the magnetic cilia are perpendicular to the small cover glass. Then the small cover glass is glued to the large cover glass to complete the preparation of the magnetic cilia force sensor. Figure 6 As shown, the flexible magnetic material segment end of the magnetic cilia is fixed to the base, and the flexible non-magnetic material segment end is a free end.

[0074] The parameters of the magnetic fiber force sensor are as follows:

[0075]

[0076] The magnetic cilia are discretized into several segments, each of which is considered as a magnetic dipole segment. For the magnetic dipole segment at any position z, the following force-magnetic coupling model is adopted:

[0077]

[0078] in:

[0079] The concentrated force load is applied at a distance H from the fixed end of the magnetic cilia in the z-axis direction. L1 is the initial length of the flexible non-magnetic material segment in the z-axis direction, and L2 is the initial length of the flexible magnetic material segment in the z-axis direction. Figure 1 As shown. E1 is the elastic modulus of the flexible non-magnetic material, E2 is the elastic modulus of the flexible magnetic material. z is the coordinate along the axis of the magnetic cilia when there is no concentrated load, x and y are the coordinates of two axes perpendicular to each other in the plane perpendicular to the z axis, dB x 、dB y 、dB z are the magnetic field intensity components of the magnetic dipole segment in the x-axis, y-axis, and z-axis directions, μ0 is the vacuum magnetic permeability, R is the radius of the magnetic cilia, M is the magnetization intensity, a=|a| is the distance from the magnetic field observation point to the magnetic dipole segment, a is the position vector of the magnetic field observation point relative to the magnetic dipole segment, θ = θ(z) is the rotation angle of the magnetic cilia at position z, is the angle between the direction of the concentrated force and the x-axis, (x0, y0, z0) are the coordinates of the magnetic field observation point, and w(z) is the deflection of the magnetic ciliary body at position z. The spatial magnetic field distribution of the entire magnetic ciliary body is obtained by superimposing the magnetic fields of all magnetic dipole segments based on the superposition of magnetic fields.

[0080] Specifically, the spatial magnetic field distribution of the entire magnetic cilia in the x-axis, y-axis, and z-axis directions can be calculated by the following formula:

[0081]

[0082] See also Figure 1 , z1 represents the length of the flexible non-magnetic material segment in the z-axis direction, and z2 represents the length of the magnetic cilium as a whole in the z-axis direction.

[0083] z1 and z2 are determined by the following equations:

[0084]

[0085] Where: h is the distance between the application position of the concentrated force load and the fixed end of the magnetic cilia in the z-axis direction, θ2 is the rotation angle of the application position of the concentrated force load, F is the concentrated force load, I is the section moment of inertia, I = πd 4 / 64, d=2R is the diameter of the magnetic cilia, and θ1 is the rotation angle of the top position of the flexible non-magnetic material segment.

[0086] Considering the magnetic cilia as cantilever beams, the solution for the deflection distribution of the magnetic cilia in the z-axis direction is:

[0087]

[0088] The above model is used to calculate the relationship between the magnitude and direction of the concentrated force load on the prepared magnetic cilia and the change in magnetic field intensity, such as Figure 7 As shown in the figure, this shows the relationship between the change in magnetic field and the magnitude of the force when the force is parallel to the coordinate axis. When the force is not parallel to the coordinate axis, the magnitude and direction of the force can be calculated using the relationship between the total magnetic field and its components. When the force is small, the graph has good linearity and can also be fitted using a linear function.

[0089] The prepared magnetic cilia were loaded in various directions using the Zhiqu DS2 high-precision digital push-pull force gauge, and the experimental results were compared with the calculated results. Figure 8 As shown, the error between the experimental value and the theoretical value is only R 2 :B x =0.995,B y =0.993.

[0090] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A ciliary magnetic tactile sensing method for concentrated force load, characterized in that: The magnitude and direction of the concentrated force load are calculated based on the magnetic field distribution around the magnetic cilia using the force-magnetic coupling model; The magnetic cilia are composed of a flexible non-magnetic material segment and a flexible magnetic material segment, wherein the flexible non-magnetic material end is fixed to the base and the flexible magnetic material end is a free end; The magnetic cilia are discretized into several segments, each of which is regarded as a magnetic dipole segment. For a magnetic dipole segment at any position z, the force-magnetic coupling model is as follows: in: z is the coordinate along the axis of the magnetic cilia when there is no concentrated load, x and y are the coordinates of two axes perpendicular to each other in the plane perpendicular to the z axis, dB x 、dB y 、dB z are the magnetic field intensity components of the magnetic dipole segment in the x-axis, y-axis, and z-axis directions, μ0 is the vacuum magnetic permeability, R is the radius of the magnetic cilia, M is the magnetization intensity, a=|a| is the distance from the magnetic field observation point to the magnetic dipole segment, a is the position vector of the magnetic field observation point relative to the magnetic dipole segment, θ = θ(z) is the rotation angle of the magnetic cilia at position z, is the angle between the direction of concentrated force load application and the x-axis, (x0, y0, z0) are the coordinates of the magnetic field observation point, and w(z) is the deflection of the magnetic cilia at position z; The spatial magnetic field distribution of the entire magnetic cilium is obtained by superimposing the magnetic fields of all magnetic dipole segments based on the superposition of magnetic fields.

2. The ciliary magnetic tactile sensing method for concentrated force load according to claim 1, characterized in that: The spatial magnetic field distribution of the entire magnetic cilia in the x-axis, y-axis, and z-axis directions is calculated by the following formula: Wherein, z1 represents the length of the flexible non-magnetic material segment in the z-axis direction, and z2 represents the length of the entire magnetic cilium in the z-axis direction.

3. The ciliary magnetic tactile sensing method for concentrated force load according to claim 2, characterized in that: z1 and z2 are determined by the following equations: Where: L1 is the initial length of the flexible non-magnetic material segment in the z-axis direction, h is the distance between the concentrated force load application position and the magnetic cilium fixed end in the z-axis direction, θ2 is the angle of the concentrated force load application position, L2 is the initial length of the flexible magnetic material segment in the z-axis direction, F is the concentrated force load, E2 is the elastic modulus of the flexible magnetic material, I is the section moment of inertia, I = πd 4 / 64, d = 2R is the diameter of the magnetic cilium, θ1 is the rotation angle of the top position of the flexible non-magnetic material segment; Considering the magnetic cilia as cantilever beams, the solution for the deflection distribution of the magnetic cilia in the z-axis direction is: Wherein, E1 is the elastic modulus of the flexible non-magnetic material.

4. The ciliary magnetic tactile sensing method for concentrated force load according to claim 1, characterized in that: When there is no concentrated force load, the magnetization direction of the magnetic cilia is the axial direction of the magnetic cilia.

5. The ciliary magnetic tactile sensing method for concentrated force load according to claim 1, characterized in that: The magnetic cilia are elongated structures with cylindrical or rectangular cross-sections, a length of 1 to 50 mm, and a diameter of 0.1 to 10 mm.

6. The ciliary magnetic tactile sensing method for concentrated force load according to claim 1, characterized in that: The Young's modulus of the flexible magnetic material segment is greater than the Young's modulus of the flexible non-magnetic material segment.

7. The ciliary magnetic tactile sensing method for concentrated force load according to claim 1, characterized in that: The flexible non-magnetic material segment is a flexible polymer.

8. The ciliary magnetic tactile sensing method for concentrated force load according to claim 1, characterized in that: The flexible magnetic material segment is prepared by compounding hard magnetic powder with a flexible polymer matrix.

9. The ciliary magnetic tactile sensing method for concentrated force load according to claim 1, characterized in that: The magnetic field distribution around the magnetic cilia is detected by a magnetic field sensor; The magnetic field sensor is a Hall sensor, a magnetoresistive sensor or a fluxgate sensor.

10. The ciliary magnetic tactile sensing method for concentrated force load according to claim 1, characterized in that: The substrate is a flexible or rigid material, including silicone, PDMS or glass.

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