Hemispherical magnetic tactile sensor for triaxial force detection

Abstract

The invention relates to a hemispherical magnetic tactile sensor for triaxial force detection. The sensor comprises a neodymium iron boron-silica gel elastomer magnetic cylinder, a silica gel elastomer shell, a TMR2003 element and a printed circuit board, wherein the four TMR2003 elements are arranged on the rectangular printed circuit board in a rotating mode, the silica gel elastic body covers the printed circuit board and wraps the four TMR2003 elements arranged in the silica gel elastic body, a cylindrical hole is formed in the top of the silica gel elastic body, and the neodymium iron boron-silica gel elastic body magnetic cylinder is embedded into the cylindrical hole. The sensor has the advantages of being high in sensitivity, small in size, not prone to plastic deformation, capable of measuring force in multiple directions and the like, and the magnitude and the direction of static force can be accurately measured.

Description

Technical Field

[0001] The present invention designs and manufactures a hemispherical magnetic tactile sensor for three-axis force detection based on NdFeB magnetic particles and silicone elastomer. The sensor can accurately detect the deformation of the main part of the silicone elastomer of the sensor through the comprehensive output of the TMR2003 array, thereby realizing the detection of three-axis force. Background Art

[0002] A tactile sensor is a sensor that can sense the contact force, shape, surface roughness and other characteristics of an object. With the continuous development and maturity of today's intelligent technology, the intelligent industry represented by robotics technology has rapidly emerged, and touch plays a vital role in the interaction between people and the external environment.

[0003] Currently, the widely used tactile sensors include piezoresistive, photoelectric, capacitive, and piezoelectric tactile sensors. Most of them are only used to measure normal force and detect deformation caused by static normal force. The detection direction is single. The current three-dimensional force sensors are mainly capacitive, resistive, and piezoelectric. They are complex to manufacture and face difficult decoupling problems. There is an urgent need to develop a new magnetic tactile sensor that can be used to measure both tangential force and normal force.

[0004] The patent "CN116380324A A three-dimensional force sensor based on iron-gallium alloy" is based on the magnetostrictive inverse effect of the iron-gallium alloy wire. It measures the different deformation amounts of each part of the iron-gallium alloy wire under a bias magnetic field, resulting in different outputs generated by the TMR element to determine the size and direction of the force. It can measure the tangential force and normal force. However, the iron-gallium alloy has high strength and small deformation amount, which will lead to a small force measurement range of the sensor. Otherwise, the iron-gallium alloy wire will produce irreversible deformation. The use of the magnetostrictive inverse effect requires a bias magnetic field and the addition of a permanent magnet in the sensor unit, which will complicate the design of the sensor unit and make it difficult to miniaturize the sensor. Summary of the invention

[0005] The purpose of the present invention is to provide a magnetic tactile sensor that can simultaneously measure tangential force and normal force, in order to solve the technical problems that the current sensors have a single force measurement direction, the three-dimensional force sensor is complex in design, and it is difficult to decouple. The sensor is composed of four parts, omitting the permanent magnet. The main part is a NdFeB-silicone elastomer magnetic cylinder, which is wrapped with a hemispherical elastic shell made of silicone elastomer. By integrally coating the TMR element on the flexible printed circuit board, the TMR element can better detect the deformation of the elastomer, and at the same time, it can prevent the pins of the TMR element from being desoldered, thereby increasing the service life of the sensor. The sensor of the present invention has the advantages of high sensitivity, small size, not prone to plastic deformation, and the ability to measure multi-directional forces, and can achieve accurate measurement of the magnitude and direction of static forces.

[0006] The technical solution of the present invention is:

[0007] A hemispherical magnetic tactile sensor for triaxial force detection, the sensor comprising a NdFeB-silicone elastomer magnetic cylinder, a silicone elastomer housing, a TMR2003 element and a printed circuit board;

[0008] There are four TMR2003 elements arranged in a rotation on a rectangular printed circuit board, a silicone elastomer covers the printed circuit board and encapsulates the four TMR2003 elements arranged in a rotation, there is a cylindrical hole on the top of the silicone elastomer, and a NdFeB-silicone elastomer magnetic cylinder is embedded in it; the center of the rotating array composed of the four TMR elements, the center of the magnetic cylinder and the center of the silicone elastomer coincide;

[0009] The upper part of the silicone elastic body is a hemisphere, and the lower part is a cylinder, and the two are integrated; the diameter of the hemisphere, the diameter of the cylinder and the short side length of the printed circuit board are the same;

[0010] The printed circuit board is a PCB board;

[0011] The TMR element is TMR2003; the magnetic sensitive direction of the TMR2003 element is the X-axis direction, that is, from the three-pin direction to the two-pin direction, S0T23-5 package, size 3mm×3mm×1.45mm; the printed circuit board size is 15mm×20mm;

[0012] The upper part of the silicone elastomer shell is a hemisphere with a radius of 7.5 mm, and the lower part is a cylinder with a radius of 7.5 mm and a height of 2 mm;

[0013] The depth of the cylindrical hole is the same as the radius of the hemisphere, which is 7.5 mm;

[0014] The NdFeB-silicone elastomer magnetic cylinder is formed by mixing NdFeB magnetic particles and silicone prepolymer in a mass ratio of 3:1.

[0015] The chemical formula of the NdFeB particles is Nd2Fe 14 B1; particle size is 0.1-0.2mm.

[0016] The essential features of the present invention are:

[0017] Based on the fact that current pressure sensors can only measure force in a single direction, and the three-dimensional force sensors have complex structures and difficult decoupling, in current technology, tactile sensors designed with magnetostrictive materials mostly use alloys as the sensing part, which requires a large external force to deform it, but the external force should not be too large, otherwise plastic deformation will easily occur, and the force measurement range and service life will be limited; at the same time, electronic skin tactile sensors made of magnetic films have problems such as a single force measurement direction, limited measurement accuracy, and difficulty in maintaining consistent results with different magnetizing methods; therefore, a hemispherical magnetic tactile sensor structure that can be used for both tangential force and normal force detection is designed by selecting new materials, designing different structures, and changing the magnetizing method.

[0018] The present invention combines a magnetostrictive tactile sensor with a magnetic film electronic skin, uses a magnetic cylinder with a simple magnetization method to replace the magnetostrictive alloy material, uses a three-dimensional structure to replace the planar structure of the magnetic film, and uses a silicone elastomer with strong flexibility and resilience as the sensor main force-bearing structure, so that the sensor has a large deformation amount and is not prone to plastic deformation. The service life and force measurement range are greatly improved, and at the same time, tactile perception of multiple directional forces such as normal force and tangential force can be realized.

[0019] In the present invention, the part receiving the external force is a hemispherical silicone elastomer shell. When the shell is subjected to the external force, the overall structure is deformed, driving the magnetic cylinder embedded therein to be deformed. The projection of the magnetic cylinder on the bottom printed circuit board and the relative position of the TMR element are changed, so that the magnetic field at the position of the TMR element changes. The TMR magnetic sensitive direction is rotated and arranged to ensure that the relative position of each TMR element relative to the central magnetic cylinder is the same, and it is easy to detect the magnetic field change caused by the deformation caused by the external force.

[0020] The beneficial effects of the present invention are:

[0021] 1. The present invention adopts NdFeB particles which are easy to magnetize, have good magnetism after magnetization and have uniform particle size, and silicone prepolymers with good elasticity and strong flexibility in a mass ratio of 3:1 to form a magnetic cylinder. The flexibility of silicone makes it easy to produce a large deformation after receiving stress, while it is not easy to produce plastic deformation. It recovers quickly after receiving stress and has good dynamic detection performance (response time reaches 23ms, and recovery time reaches 20ms). The output generated by the selected TMR2003 is derived from a push-pull Wheatstone full-bridge structure, has a single sensitive direction, points from the three-pin direction to the two-pin direction, and generates a step output in the magnetic sensitive direction, thereby increasing the output voltage of the sensor.

[0022] 2. The PCB board with the TMR element welded on it and the TMR element above it are covered by a silicone elastomer shell, which not only prevents the TMR element from falling off under the action of external stress, but also increases the overall flexibility of the sensor, so that the sensor unit has better flexibility when subjected to external stress, and increases the deformation of the sensor.

[0023] 3. The silicone elastic shell of the present invention is bonded to the PCB board after the prepolymer is demolded from the mold, and can be used to maintain the distance and position between the NdFeB-silicone elastomer magnetic cylinder and the TMR, reserving sufficient space for the deformation of the magnetic cylinder, while allowing the TMR to work in a linear range. Within the normal force range of 0-30N and the tangential force range of 0-10N, the output of the sensor can maintain a linear output.

[0024] 4. Compared with the prior art, the present invention applies soft magnetic cylinders to the field of normal force and tangential force detection, providing a new method for the detection of three-axis force. In the three-axis force detection experiment, three-axis force detection can be performed in a simple way to identify the direction of the axial force.

[0025] 5. The preparation process of the present invention is simple, low-cost, does not require the addition of complex signal processing circuits, and can accurately identify three-axis forces. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a disassembled diagram of the various parts of the hemispherical tactile sensor used for three-axis force detection;

[0027] Figure 2 This is the overall structural assembly diagram of the hemispherical tactile sensor used for three-axis force detection;

[0028] Figure 3 This is the bottom PCB circuit diagram of the hemispherical tactile sensor used for three-axis force detection;

[0029] Figure 4 This is a schematic diagram of the magnetic field of the NdFeB-silicone elastomer magnetic cylinder inside the sensor after magnetization;

[0030] Figure 5 is the output voltage of the TMR2003 element when the hemispherical sensor receives the normal force;

[0031] Figure 6 It is the projection of the direction of the tangential force on the hemispherical tactile sensor on the TMR2003 surface;

[0032] Figure 7 It is a schematic diagram of the delay when the hemispherical sensor is loaded and unloaded with pressure;

[0033] Figure 8It is a schematic diagram of the output voltage of the TMR2003 element array on the PCB board when the hemispherical sensor receives a tangential force;

[0034] Among them, 1-NdFeB-silicone elastomer magnetic cylinder, 2-silicone elastomer housing, 3-TMR2003 element, 4-printed circuit board; DETAILED DESCRIPTION

[0035] The magnetic tactile sensor designed by the present invention is composed of a NdFeB-silicone elastomer magnetic cylinder, a silicone elastomer shell, a tunnel magnetoresistive element and a printed circuit board, which can accurately sense static and dynamic forces and accurately identify the directions of axial forces in different directions; the magnetized NdFeB-silicone elastomer magnetic cylinder serves as the sensing part of the magnetic tactile sensor, which can provide a stable magnetic field for the sensor unit and sense external stress stimulation. After stress is applied to the silicone elastomer shell of the magnetic tactile sensor, the silicone elastomer shell will deform, driving the internal magnetic cylinder to undergo elastic deformation and causing the magnetic domain inside the cylinder to change, thereby causing the relative position between the magnetic cylinder and the TMR element to change, and the magnetic field around the TMR element to change. The TMR element will detect the change in the magnetic field and convert it into a change in the internal magnetic resistance. Under the action of the tunnel magnetoresistive effect, an output voltage is generated through a built-in unique Wheatstone bridge circuit. The output voltage of the TMR element is connected to the data acquisition card via the printed circuit board at the bottom, and then converted into an intuitive output voltage curve image by the computer. The four TMR elements are completely wrapped inside the silicone elastomer shell to increase the measurement accuracy while preventing them from falling off under stress.

[0036] The four TMR elements on the printed circuit board form an array, and the output voltage waveform is displayed by computer software. The common output of the four elements is combined for further analysis and processing, which realizes the detection of normal force and tangential force. The sensor unit can be used in robots, etc. to perform corresponding touch information recognition.

[0037] In the present invention, the hemispherical tactile sensor unit structure design adopts the combination of four TMR elements for sensing, which greatly improves the pressure test range and accuracy of the tactile sensor, detects the tangential forces in different directions, and judges the size and direction of the external shear compressive stress by observing the output voltage of the corresponding TMR2003 element, thereby improving the accuracy and sensitivity while avoiding the recognition error caused by component damage. It has good rebound performance and high sensitivity, and has a larger force measurement range and service life than the rigid iron-gallium alloy wire sensor, and can provide a better application environment.

[0038] The present invention is further described in detail below. This embodiment is only a specific description of the invention and is not considered as a definition of the scope of protection.

[0039] Example 1

[0040] The disassembly diagram of the various parts of the hemispherical tactile sensor of the present invention is as follows: Figure 1 As shown, it is composed of a NdFeB-silicone elastomer magnetic cylinder 1, a silicone elastomer shell 2, a TMR2003 element 3, and a printed circuit board 4;

[0041] Among them, there are 4 TMR2003 elements arranged in rotation on the rectangular printed circuit board, the silicone elastomer covers the printed circuit board and wraps the four TMR2003 elements 3 arranged in rotation therein, there is a cylindrical hole with a radius of 2mm on the top of the silicone elastomer 2, and a NdFeB-silicone elastomer magnetic cylinder magnetized vertically downward is embedded in it; the center of the rotating array composed of the four TMR elements, the center of the magnetic cylinder and the center of the silicone elastomer coincide.

[0042] The printed circuit board is a PCB board;

[0043] The upper part of the silicone elastic body is a hemisphere, and the lower part is a cylinder, and the two are integrated; the diameter of the hemisphere, the diameter of the cylinder and the short side length of the printed circuit board are the same;

[0044] The depth of the cylindrical hole is the same as the radius of the hemisphere, which is 7.5 mm;

[0045] The overall structure of the hemispherical tactile sensor is shown in the figure Figure 2 As shown, four TMR2003 components 3 are coated under the hemispherical structure and fixed on the bottom PCB circuit board (the distances from the four TMR2003 components 3 to the center of the hemisphere are the same, and the line connecting two adjacent TMR2003 components 3 to the center is at a 90-degree angle). The distance between two TMR2003 components on the same straight line is 7 mm, and an organic silicone elastic shell 2 is cast thereon to cover the PCB board and the TMR2003 components as a whole.

[0046] The TMR element 3 is TMR2003; the magnetic sensitive direction of the TMR2003 element is the X-axis direction, that is, from the three-pin direction to the two-pin direction, S0T23-5 package, size 3mm×3mm×1.45mm;

[0047] The silicone elastomer shell is made by mixing and curing liquid A and liquid B of Smooth-On Company in a mass ratio of 1:1. After mixing liquid A and liquid B, put them into a blender and stir for 30 minutes. After stirring to make liquid A and liquid B fully mixed, put the obtained silicone elastomer prepolymer solution into a vacuum defoaming machine for 20 minutes of defoaming treatment. After removing the internal bubbles, let it stand at room temperature for 180 minutes, and pour it into a mold made of R4600 photosensitive resin through 3D printing process. The upper part of the silicone elastomer shell is a hemisphere with a radius of 7.5 mm, and the lower part is a cylinder with a radius of 7.5 mm and a height of 2 mm. The two parts are integrally cast and demolded to obtain a silicone elastomer shell;

[0048] The method for preparing the NdFeB-silicone elastomer cylinder comprises the following steps:

[0049] The unmagnetized NdFeB magnetic particles are mixed with the silicone prepolymer obtained by mixing liquid A and liquid B in a mass ratio of 1:1 in a mass ratio of 3:1, and the mixture is placed in a blender and stirred for 30 minutes to make the NdFeB particles evenly distributed in the silicone prepolymer to obtain the NdFeB-silicone prepolymer; the NdFeB-silicone prepolymer is added to a vacuum degassing machine for 30 minutes of degassing treatment; after the treatment, it is poured into a 3D printed cylindrical resin mold, a layer of film is covered on the top layer, and the NdFeB-silicone flexible cylinder is demolded after curing at room temperature for 120 minutes; the cylinder is then axially magnetized in a vertical downward direction to obtain the NdFeB-silicone magnetic cylinder;

[0050] The NdFeB-silicone elastomer magnetic cylinder has a radius of 2 mm and a height of 7.5 mm;

[0051] The circuit on the printed circuit board is as follows Figure 4 As shown, 5 is the GND terminal of the TMR2003 element, 6 is the VCC terminal, 7-10 are the V- terminals of the TMR2003 element array, and 11-14 are the V+ terminals of the TMR2003 element array;

[0052] The arrangement of the TMR2003 sensor array on the printed circuit board is as follows: Figure 3As shown, the magnetic sensitive direction of TMR2003 points from three pins to two pins, and the magnetic sensitive directions of the four TMR2003 elements (the direction of the three pins points to the direction of the two pins) are the same relative to the direction of the central magnetic cylinder, so they are arranged in a rotational manner; when the silicone elastomer shell is deformed by external compressive stress, the central NdFeB-silicone elastomer magnetic cylinder is deformed and bent, and the relative position between it and the four TMR2003 elements on the bottom PCB board changes, and the magnetic field around the TMR2003 element changes. After the pressure is removed, thanks to the good elasticity of the silicone elastomer, it can quickly recover to its original state and complete the tactile perception process; the silicone elastomer will not undergo plastic deformation within the maximum tolerable pressure range, and has good recovery performance. While completing tactile perception, it can also protect the TMR2003 element and the bottom PCB board wrapped therein, so that they will not be deformed and damaged under the action of external compressive stress within the effective force measurement range;

[0053] The radius of the NdFeB-silicone elastomer magnetic cylinder is 2 mm and the height is 7.5 mm. The magnetization technology shown is a well-known technology and can also be carried out through commercial commissions.

[0054] Embodiment 2-9

[0055] On the basis of Example 1, the lengths of different NdFeB-silicone elastomer magnetic cylinders are explored. When the upper surface of the magnetic cylinder is fixed, different lengths of NdFeB-silicone elastomer magnetic cylinders are set to 1.5mm (i.e., the bottom is suspended), 2.5mm, 3.5mm, 4.5mm, 5.5mm, 6.5mm, 7.5mm, and 8.5mm. They are prepared in groups, and the magnetic field strength generated on the TMR2003 component surface is detected after magnetization. The test results are as follows: the maximum magnetic field intensity generated by the 1.5mm-7.5mm NdFeB-silicone elastomer magnetic cylinder at the TMR2003 component height increases with the increase of the length of the NdFeB-silicone elastomer magnetic cylinder, and when the length is 8.5mm, the bottom of the cylinder is in contact with the TMR component height, and the magnetic field generated at this height is distorted, so 7.5mm is selected as the optimal length.

[0056] Examples 10-14

[0057] On the basis of the same embodiment 1, different mass ratios of NdFeB-silicone elastomer are studied, and the mass ratios of NdFeB and silicone elastomer are set to 1:1, 2:1, 3:1, 4:1, and 5:1 for preparation. After completion, the NdFeB-silicone elastomer magnetic cylinder is axially magnetized, and its magnetic field strength and hardness are tested after magnetization. This embodiment finds that when the mass ratio is 1:1, the prepared NdFeB-silicone elastomer magnetic cylinder has the best flexibility, but the magnetic field intensity generated is too small; when the mass ratio is 5:1, the magnetic field intensity generated is the largest, but under this ratio, the magnetic cylinder has a large hardness, is difficult to bend, and is easily broken under stress, so 3:1 is determined to be the best ratio.

[0058] The software and protocols involved in the present invention are all known technologies.

[0059] Test Example 1:

[0060] Using one of the four TMR2003 elements at the bottom as the detection component, a pressing contact with a diameter of 8 mm is placed above the hemispherical tactile sensor to conduct a pressing experiment to verify the relationship between the external stress and the output voltage of the hemispherical tactile sensor, and to test its force measurement range and output voltage signal range.

[0061] Experimental platform construction: Assemble the sensor according to the hemispherical tactile sensor pattern; the experimental platform consists of a push-type contact with a diameter of 8mm, a digital push-pull force gauge, a DC regulated power supply, a DH-8303 dynamic data acquisition card, and a computer; fix the hemispherical tactile sensor on the base of the digital push-pull force gauge, fix the circular push-type contact on the contact end of the push-pull force gauge, adjust the rotation axis of the digital push-pull force gauge so that the contact point of the push-pull force gauge is facing the top of the hemispherical tactile sensor; use a DC regulated power supply to provide power support for the TMR2003 element, the + end of the DC power supply is connected to the output terminal VCC, the - end of the DC power supply is connected to the output terminal GND, and the + and - ends of one acquisition channel of the data acquisition card are respectively connected to the differential voltage V+ and V- ends of the same TMR2003 element. The output voltage signal after acquisition is displayed on the computer.

[0062] Experimental process and results: A digital push-pull force gauge generates uniform and vertical downward pressure, and applies a normal force of 0-50N to the top of the hemispherical magnetic tactile sensor in steps of 5N. The experiment is carried out in this way, and the output voltage is recorded in sequence. The voltage waveform is plotted as shown in the figure below. Figure 5As shown. By observing the output voltage waveform, it can be seen that the output voltage in the first half increases more as the pressure increases, and the output voltage in the second half changes less as the pressure increases. The reason is that when the pressure is initially increased, the magnetic field intensity on the height surface of TMR2003 is small. When the hemispherical tactile sensor is deformed by external pressure, the magnetic field intensity on the surface of TMR2003 changes less. As the displacement increases, the magnetic field intensity gradually increases. TMR2003 works in the linear region. When the external pressure continues to increase, the magnetic field intensity is saturated. The magnetic field generated by the magnetic cylinder saturates the TMR2003 element, so the output voltage does not change much. It can be seen that the normal force test range of the hemispherical tactile sensor is 0-50N, and it has good linearity at 0-30N. At the same time, the pressure is applied and removed to the sensor, and its response and recovery time during the pressure loading and unloading process are tested. The data is recorded and the output voltage graph is drawn as shown in the figure. Figure 7 As shown, by observing its waveform, we can see that the response time is 23ms and the recovery time is 20ms. It can be seen that the hemispherical tactile sensor has excellent sensitivity and responsiveness.

[0063] Test Example 2:

[0064] The array composed of four TMR2003 elements is used as the detection part. The pressing contact is replaced with a circular contact with a diameter of 2mm. The hemispherical tactile sensor is bonded to the side of the test bench. The pressing direction of the digital push-pull force gauge is to the side of the hemispherical tactile sensor, that is, a tangential force is applied to the hemispherical tactile sensor to verify the output of the four TMR2003 elements. The purpose of this experiment is to conduct a pressing test to verify the tangential force measurement range of the hemispherical tactile sensor and the output law of the TMR2003 element array.

[0065] Experimental platform construction: according to Figure 1 Figure 2 As shown in the figure, assemble the hemispherical tactile sensor; the experimental platform consists of a circular contact with a diameter of 2mm, a digital push-pull force gauge, a DC regulated power supply, a DH-8303 dynamic data acquisition card, and a computer; the hemispherical tactile sensor is bonded to the side of the cube block, the cube block is bonded to the base of the digital push-pull force gauge, the circular pressing head is fixed to the contact end of the push-pull force gauge, and the rotating shaft of the digital push-pull force gauge is adjusted so that the circular contact faces the side of the hemispherical tactile sensor; a DC regulated power supply is used to provide power support for the TMR2003 element, the + end of the DC power supply is connected to the output terminal VCC, the - end of the DC power supply is connected to the output terminal GND, and the + and - ends of one acquisition channel of the data acquisition card are respectively connected to the differential voltage V+ and V- ends of the same TMR2003 element, and a total of four acquisition channels are used, and the connection method is the same as the first one. The output voltage signal after acquisition is displayed on the computer end.

[0066] Experimental process and results:

[0067] A uniform, vertical downward pressure is generated by a digital push-pull force gauge and applied to the side of the hemispherical tactile sensor as a tangential force in the direction of U1. Figure 6 As shown; with 1N as the step length, apply 0-10N tangential force, record the output voltage value of each TMR2003 element in sequence, and draw the output voltage line graph as shown Figure 8 As shown; analyzing its output, it can be seen that the change of magnetic field in the magnetic sensitive direction of TMR2003 element will produce a step output, just like the output of U2 and U4. After the step, the output voltage remains basically unchanged; while the output voltage value of U1 gradually increases with the increase of tangential force, and the output of U3 gradually decreases with the increase of tangential force; it can be seen that within the tangential force range of 1-10N, the direction of the tangential force can be determined, and the magnitude of the tangential force can be identified.

[0068] Through the above embodiments and test examples, it can be known that the hemispherical tactile sensor for three-axis force detection of the present invention is composed of four parts: NdFeB-silicone elastomer magnetic cylinder, silicone elastomer shell, TMR2003 element array and printed circuit board, which can complete the direction and magnitude recognition of the three-axis force. The NdFeB-silicone elastomer magnetic cylinder with a radius of 2mm and a length of 7.5mm is used as the sensing part, which has a magnetic property of suitable size and good flexibility. At the same time, the silicone elastomer shell is used, which has good resilience within the force measurement range, will not undergo plastic deformation, and has good service life and repeatability. The axially magnetized NdFeB-silicone elastomer magnetic cylinder is deformed after being subjected to pressure, so that the magnetic field strength around the four TMR2003 elements changes. Due to the tunnel magnetoresistance effect of the TMR2003 element, a differential output is performed through a full-bridge circuit structure to obtain an output voltage waveform. The three-axis force recognition is performed based on the relationship between the input pressure and the output voltage. The recognition ranges of the normal force and the tangential force are 0-50N and 0-10N respectively, which can complete the three-axis force recognition function.

[0069] Matters not covered by the present invention are known technologies.

Claims

1. A hemispherical magnetic tactile sensor for three-axis force detection, characterized in that: The sensor includes a NdFeB-silicone elastomer magnetic cylinder, a silicone elastomer housing, a TMR2003 element, and a printed circuit board; There are four TMR2003 components arranged in a rotation on a rectangular printed circuit board, a silicone elastomer covers the printed circuit board and encapsulates the four TMR2003 components arranged in a rotation, and there is a cylindrical hole on the top of the silicone elastomer, in which a NdFeB-silicone elastomer magnetic cylinder is embedded; The upper part of the silicone elastic body is a hemisphere, and the lower part is a cylinder, and the two are integrated; the diameter of the hemisphere, the diameter of the cylinder and the short side length of the printed circuit board are the same; The NdFeB-silicone elastomer magnetic cylinder is formed by mixing NdFeB magnetic particles and silicone prepolymer in a mass ratio of 3:

1.

2. The hemispherical magnetic tactile sensor for three-axis force detection according to claim 1, characterized in that: The chemical formula of the NdFeB particles is Nd2Fe 14 B1; particle size is 0.1-0.2mm.

3. The hemispherical magnetic tactile sensor for three-axis force detection according to claim 1, characterized in that: The printed circuit board is a PCB board.

4. The hemispherical magnetic tactile sensor for three-axis force detection according to claim 1, characterized in that: The TMR element is TMR2003; the magnetic sensitive direction of the TMR2003 element is the X-axis direction, that is, from the three-pin direction to the two-pin direction, S0T23-5 package, size 3mm×3mm×1.45mm; the printed circuit board size is 15mm×20mm; The upper part of the silicone elastomer shell is a hemisphere with a radius of 7.5 mm, and the lower part is a cylinder with a radius of 7.5 mm and a height of 2 mm; The depth of the cylindrical hole is the same as the radius of the hemisphere, both of which are 7.5 mm.

5. The hemispherical magnetic tactile sensor for three-axis force detection according to claim 1, characterized in that: The center of the rotating array composed of four TMR elements, the center of the magnetic cylinder and the center of the silicone elastomer coincide.

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