A three-dimensional force tactile sensor based on iron-gallium alloy

Abstract

The application discloses a three-dimensional force tactile sensor based on iron-gallium alloy. The sensor comprises a base and four sensing units; two groups of the four sensing units are oppositely arranged on two sides of the base; the base comprises a convex block and a support; the lower surface of the convex block is fixedly connected with the upper surface of the support, and the centers of the two are overlapped; each sensing unit comprises an iron-gallium wire, a base, a cylindrical contact, a square permanent magnet and a TMR element; the square permanent magnet provides a bias magnetic field, and the TMR element detects the force of the sensing unit; the average value and the difference value of the force detected by the four sensing units are used to determine the size and the direction of the tangential force and the size of the normal force applied on the sensor. The application not only has excellent static force test performance, but also has dynamic force test performance, and has relatively fast response time and recovery time.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of tactile sensors. A three-dimensional force tactile sensor based on iron-gallium alloy is designed based on inverse magnetostrictive effect, which can be installed on a mechanical hand to measure normal force and tangential force. BACKGROUND

[0002] Tactile sensors are important equipment for intelligent robots to interact with the external environment, and are the basis for precise perception, grasping and operation of objects. Tactile signals can allow robots to directly perceive the physical properties of the environment and target objects, but most current sensors are single-direction force tactile sensors, which have gradually failed to meet the requirements of robot sensing technology. Therefore, the development of tactile sensors is gradually moving towards three-dimensional force measurement. Current three-dimensional force tactile sensors are mainly divided into capacitive, resistive and piezoelectric types. Capacitive three-dimensional force tactile sensors have complex structures, are greatly affected by temperature, and have large differences in tangential and normal sensitivity and range. Resistive three-dimensional tactile sensors have simple structures, but have slow response speed and large hysteresis. Piezoelectric three-dimensional force tactile sensors have unstable output voltage and can only measure dynamic force. As a new type of magnetic material, magnetostrictive material can make up for the shortcomings of other types of tactile sensors and improve the performance of tactile sensors in various indicators, with high sensitivity, wide force detection range and fast response speed. Figure 11 As shown in FIG. 1, the existing three-dimensional force magnetostrictive sensor (patent number "CN114136526A Three-dimensional force tactile sensor based on inverse magnetostrictive effect", document "Zhao Xuan. Design and application of magnetostrictive three-dimensional force tactile sensor structure [D]. Hebei University of Technology, 2022.") uses iron-gallium wire and Hall elements as core components. As shown in FIG. 1, two permanent magnets 13 are placed on both sides of the iron-gallium wire 11 to provide a bias magnetic field, and four external Hall elements 14 are placed behind the four iron-gallium wires 11 to detect the size of the force on the contact by detecting the change of the magnetic field; a small permanent magnet 9 is placed below the contact 8, and four internal Hall elements 10 are symmetrically placed below the contact 8 and the small permanent magnet 9 to detect the direction of the contact movement, which can measure the direction and size of three-dimensional force at the same time, has the characteristics of simple structure, low cost, good static and dynamic characteristics, but the anti-interference ability of Hall element is poor, the magnetic coupling between units is large, and the change of weak magnetic field is not sensitive, which seriously affects the performance of the sensor. SUMMARY

[0003] The present application aims at the problems of large size, small range and low sensitivity of the existing three-dimensional force tactile sensor, and provides a three-dimensional force tactile sensor based on iron-gallium alloy.The PDMS substrate composed of cross-shaped pillars and bumps is arranged in the center of the sensor structure, and each of the four corners of the lower surface of the bump is provided with a sensing unit;in the sensing unit, a square permanent magnet is placed above the iron-gallium wire to provide a bias magnetic field, and a TMR element is placed obliquely below the iron-gallium wire to detect the force of the sensing unit;the average value and the difference value of the force detected by the four sensing units are used to determine the size and direction of the normal force and the tangential force applied on the sensor.The present application not only has excellent static force testing performance, but also has dynamic force testing performance, and has fast response time and recovery time, which are essential for the sensor to quickly and accurately perceive three-dimensional force.

[0004] The technical scheme of the present application is:

[0005] A three-dimensional force tactile sensor based on iron-gallium alloy, the sensor comprising a substrate and four sensing units;

[0006] The substrate comprises bumps and pillars; the lower surface of the bump is fixedly connected with the upper surface of the pillar, and the centers of the two are overlapped; the shape of the bump is a square ladder whose projection is a square; the pillar is cross-shaped; the four sensing units are distributed on the two sides of the substrate in two groups;

[0007] Each sensing unit comprises an iron-gallium wire, a base, a cylindrical contact, a square permanent magnet and a TMR element; the main body of the base is a cuboid, one side of the bottom is provided with a rectangular groove, and the middle and lower part of the other side protrudes a slope with a common bottom surface; the side surface of the upper part of the slope is centrally symmetrical and spaced apart to distribute three circular holes; three identical iron-gallium wires are horizontally arranged and parallelly distributed, one end of each wire is fixed in the circular hole of the side surface of the base, and the other end is fixed in the circular hole of the bottom beam of the cylindrical contact; the TMR element is fixed in the rectangular groove of the base; the upper surface of the base is provided with a groove, and the square permanent magnet is fixed in the groove, and the N-pole direction of the magnet points to the cylindrical contact; the four cylindrical contacts are respectively fixed on the lower surfaces of the four corners of the bump;

[0008] The cylindrical contact is a round sheet with a strip-shaped bottom beam in the lower part, and the bottom beam is centrally symmetrical and has three circular holes with the same size and spacing as the circular holes of the base;

[0009] The bump is a square ladder with a height of 0.5-2mm and a side length of 10-12mm, and the upper edge has a chamfer of 40-50°;

[0010] The pillar is cross-shaped, with a length of 6-8mm, a width of 2-4mm and a height of 2-4mm, wherein the length refers to the distance between the two corresponding edges of the cross-shaped structure, and the width refers to the length of the edge of one end of the cross-shaped structure.

[0011] The material of the convex block and the pillar is PDMS;

[0012] The iron gallium wire has a length of 5-8 mm and a diameter of 0.4-0.6 mm;

[0013] The base body is a cuboid with a height of 1.5-3.5 mm, a length of 4-6 mm and a width of 2.5-4 mm, and a triangular wedge structure is arranged at the front end of the cuboid, with a height of 0.5-1.5 mm, a width of 4-6 mm and an acute angle of 25-35°;

[0014] The cylindrical contact body is a cylinder with a height of 0.5-1.5 mm and a diameter of 3-5 mm, and the bottom is a strip-shaped bottom beam with a length of 2-4 mm, a width of 0.5-1.5 mm and a height of 1-1.5 mm;

[0015] The material of the cylindrical contact and the base is white resin;

[0016] The material of the square permanent magnet is boron steel;

[0017] The substantial features of the present application are:

[0018] The sensor is composed of four horizontally placed sensing units, a PDMS convex block and a PDMS pillar, and each sensing unit is composed of an iron gallium wire, a base, a cylindrical contact, a square permanent magnet and a TMR element. When only a normal force is applied on the sensor, the force transmitted to the four sensing units through the PDMS convex block and the pillar is uniform, and thus the size of the normal force is obtained. When a force is applied on the sensor and the force has a normal force and a tangential force, the force transmitted to the four sensing units through the PDMS convex block and the pillar is not uniform along the direction of the tangential force, and the size of the normal force can be obtained by calculating the average value, and the size of the tangential force can be obtained by calculating the difference. The iron gallium wire is fixed between the unit base and the cylindrical contact in a cantilever beam structure, and the square permanent magnet provides an initial bias magnetic field for the iron gallium wire, so that the internal magnetic domains of the iron gallium wire are arranged in a certain direction. The PDMS convex block of the sensor transmits the normal force and the tangential force received to the cylindrical contacts of the four sensing units, and the cylindrical contacts transmit the force to the iron gallium wire, so that the iron gallium wire is bent. Due to the inverse magnetostrictive effect, the arrangement of the internal magnetic domains of the iron gallium wire changes, causing the change of the surrounding space magnetic field, converting the force signal into a magnetic signal. The tunnel magnetoresistance effect of the TMR element outputs the change of the surrounding space magnetic field as a voltage signal, converts the magnetic signal into an electric signal, and finally obtains the force information through the output voltage, which has good static force and dynamic force measurement performance.

[0019] The beneficial effects of the present application are embodied as follows:

[0020] 1. Due to the inverse magnetostrictive effect of the iron gallium wire, the sensor unit can convert the force signal received on the cylindrical contact into an electric signal, and accurately measure the pressure. The pressure and the output voltage show a good linear relationship in the range of 0-5N, and when the pressure is 5N, the sensor unit outputs an electric voltage of 1542mV, and the sensitivity of the sensor unit is 308.4mV / N.

[0021] 2. The normal force and the tangential force received by the sensor PDMS bump and the support are conducted to the four sensor units, and the output of the four sensor units is processed to obtain the size of the normal force and the tangential force, thereby avoiding the decoupling problem of three-dimensional force and making the subsequent data processing more simple. The normal force and the output voltage show a good linear relationship in the range of 0-20N, and the normal force sensitivity of the tactile sensor is 71.4mV / N; the tangential force and the output voltage show a good linear relationship in the range of 0-10N, and the tangential force sensitivity of the tactile sensor is 62.6mV / N.

[0022] 3. The application not only has excellent static force test performance, but also has dynamic force test performance, and has relatively fast response time and recovery time, which is crucial for the sensor to quickly and accurately perceive three-dimensional force.

[0023] 4. The distance between the sensor units is relatively far, so that the coupling between different units is minimized, and the measurement accuracy is improved.

[0024] 5. The four sensor units are integrated on the printed circuit board, and the output terminals are concentrated on the same side, which reduces the interference between the output signals and facilitates the installation of the tactile sensing array on the mechanical surface.

[0025] 6. The application has simple process, low cost and simple data processing. DETAILED DESCRIPTION

[0026] Figure 1 It is a structure diagram of a three-dimensional force tactile sensor based on iron gallium alloy;

[0027] Among them, 1-TMR element, 2-square permanent magnet, 3-base, 4-cylindrical contact, 5-PDMS support, 6-PDMS bump, 7-iron gallium wire.

[0028] Figure 2 It is a structure disassembly diagram of a three-dimensional force tactile sensor based on iron gallium alloy;

[0029] Figure 3 It is a structure diagram of the PDMS bump and support of a three-dimensional force tactile sensor based on iron gallium alloy;

[0030] Figure 4 It is a structure diagram of a three-dimensional force tactile sensor sensing unit based on iron gallium alloy;

[0031] Figure 5 is the output curve diagram of the tactile sensor sensing unit in static force test;

[0032] Figure 6 is the output curve diagram of the tactile sensor in static normal force test;

[0033] Figure 7 is the output curve diagram of the tactile sensor in static tangential force test;

[0034] Figure 8 is the output curve diagram of the four sensing units of the tactile sensor in static force test when the angle with the vertical direction is 60° and the angle with the horizontal direction is 0°;

[0035] Figure 9 is the output curve diagram of the sensing unit of the tactile sensor in 50 times of repetitive test;

[0036] Figure 10 is the enlarged diagram of the first waveform of the repetitive test of the tactile sensor;

[0037] Figure 11 is the structural diagram of the magnetostrictive three-dimensional force tactile sensor in the prior art, wherein, Figure 11 a is the sensor structural diagram of the patent "three-dimensional force tactile sensor based on the inverse effect of magnetostriction", Figure 11 b is the disassembly diagram of the internal structure of the sensor; DETAILED DESCRIPTION

[0038] The sensor comprises a base body and four sensing units; the four sensing units are distributed in parallel in two groups, and the two groups are oppositely distributed on two sides of the base body.

[0039] The base body comprises a protrusion 6 and a support 5, both of which are made of PDMS; wherein the lower surface of the protrusion 6 is fixedly connected with the upper surface of the support 5, and the centers of the two are overlapped; the shape of the protrusion 6 is a ladder with a square projection; the support 5 is a cross shape;

[0040] The length of the support 5 is 63.6% of the side length of the protrusion 6; the length of the support 5 refers to the distance between the two corresponding edges of the cross shape.

[0041] Each sensing unit is like Figure 4The shown sensor is composed of iron-gallium wire 7, base 3, cylindrical contact 4, square permanent magnet 2 and TMR element 1; wherein the main body of base 3 is cuboid, a rectangular slot is opened on one side bottom, and a slope with a common bottom surface is protruded on the middle lower part of the other side; the side surface of the upper part of the slope is centrally symmetrical, and three circular holes are distributed at intervals; three same iron-gallium wires 7 are horizontally arranged and distributed in parallel, one end is fixed in the circular hole of the side surface of base 3, and the other end is fixed in the circular hole of the bottom beam of cylindrical contact 4; TMR element 1 is fixed in the rectangular slot of base 3; the upper surface of base 3 is provided with a groove, square permanent magnet 2 is fixed therein, and the direction of N pole of magnet 2 points to contact 4 (the permanent magnet is magnetized with a narrow side, the N and S poles are in horizontal direction, and the N pole points to contact 4); the upper surface of cylindrical contact 4 is fixed to the lower surface of the corner of protrusion 6, and (the center of protrusion 6 is symmetrically distributed, that is, the distance from the center of four contacts 4 to the center of protrusion 6 is equal);

[0042] Cylindrical contact 4 is a round sheet, and a strip-shaped bottom beam is arranged at the lower part, three circular holes are centrally and symmetrically distributed on the bottom beam, and the size and spacing are same as those of the circular holes of base 3;

[0043] The sensor has good static force and dynamic force measurement performance. When the sensor is only subjected to normal force (i.e. vertical downward force), the PDMS protrusion and the PDMS support are compressed in the vertical direction, and the normal force is uniformly transmitted to the four horizontally arranged sensing units, so that the forces acting on the four sensing units are consistent, and the output voltages are the same, thereby obtaining the size of the normal force; when the sensor is simultaneously subjected to normal force and tangential force, the PDMS protrusion and the PDMS support are compressed in the vertical direction and the tangential direction at the same time, so that the sensing units in the tangential direction are unevenly stressed, and the output voltages are different in size, the average of the output voltages of the four sensing units can be calculated to obtain the size of the normal force, and the difference of the output voltages of the four sensing units can be calculated to obtain the size of the tangential force. The square permanent magnet provides an initial bias magnetic field for the iron-gallium wire, so that the internal magnetic domains of the iron-gallium wire are arranged in a certain direction. The force acting on the sensor is transmitted to the cylindrical contact through the PDMS protrusion and the PDMS support, and then is applied to the iron-gallium wire, the iron-gallium wire is bent under stress, and the arrangement of the internal magnetic domains of the iron-gallium wire changes. Since the iron-gallium wire has a strong inverse magnetostrictive effect, the magnetic field thereof changes. The TMR element close to the root of the iron-gallium wire can detect the change of the magnetic field, and the change of the magnetic field signal is output as a voltage signal through the tunnel magnetoresistance effect. The voltage signal is collected by a data acquisition card, and the data is analyzed and processed in the computer.

[0044] The magnetostrictive tactile sensor of the application is composed of four magnetostrictive sensing units, and PDMS supports and protrusions. The magnetostrictive sensing units are all iron-gallium wires (Fe 83 Ga 17), the part for measuring the magnetic field selects a TMR2003 element, and the size is 3mm*2.8mm*1.45mm. Three iron-gallium wires are used in the four sensing units, and the wires are placed horizontally in parallel, and the two ends are inserted into the reserved hole positions of the base and the cylindrical contact, respectively. The four sensing units are divided into two groups, and the sensing units in each group are placed horizontally in parallel, and the unit spacing is 7mm. The two groups of sensing units are placed horizontally symmetrically, and the spacing between the cylindrical contacts is 3mm. The PDMS bump is placed between the cylindrical contacts of the four sensing units, and the bottom is in the same plane as the base of the sensing unit, and the upper end is parallel to the upper end of the four cylindrical contacts. The TMR2003 element is placed in the groove at the tail of the base, and is close enough to the root of the iron-gallium wire to improve the sensitivity of the measurement. The square permanent magnet is placed in the slotted position at the top of the base. The force on the sensor is applied to the cylindrical contact of the sensing unit through the PDMS bump and the PDMS support, and then conducted to the iron-gallium wire. The iron-gallium wire is bent under stress, and the arrangement of the magnetic domains inside the iron-gallium wire changes. Since the iron-gallium wire has a strong inverse magnetostrictive effect, the magnetic field changes. The TMR element close to the root of the iron-gallium wire can detect the change of the magnetic field, and output the change of the magnetic field signal as a voltage signal through the tunneling magnetoresistance effect. Then, the voltage signal is collected by the data acquisition card, so as to obtain the size of the applied force. The measurement results show that the pressure of a single sensing unit and the output voltage present a good linear relationship in the range of 0-5N. When the pressure is 5N, the output voltage of a single sensing unit is 1542mV, and the sensitivity of the sensing unit is 308.4mV / N. The normal force of the tactile sensor and the output voltage present a good linear relationship in the range of 0-20N, and the normal force sensitivity of the tactile sensor is 71.4mV / N. The tangential force of the tactile sensor and the output voltage present a good linear relationship in the range of 0-10N, and the tangential force sensitivity of the tactile sensor is 62.6mV / N.

[0045] The calculation of the output voltage and the change of the force of the unit is a known technology, and reference can be made to the literature "H. Yang, L. Weng, B. Wang and W. Huang. Design and Characterization of High-Sensitivity Magnetostrictive Tactile Sensor Array [J]. IEEE Sensors Journal, 2022 22(5):4004-4013".

[0046] The application will be further described in detail below with reference to the drawings. The embodiments are only specific descriptions of the application, and are not regarded as limitations of the protection scope.

[0047] The structure of the three-dimensional force tactile sensor is as shown in Figures 1-2As shown, it is composed of TMR element 1, square permanent magnet 2, base 3, cylindrical contact 4, PDMS pillar 5, PDMS bump 6, and iron-gallium wire 7;

[0048] The TMR element 1 has a length of 3 mm, a width of 2.8 mm, and a height of 1.45 mm, and is placed in the groove at the tail of the base of the sensing unit, with the magnetic sensitive direction in contact with the iron-gallium wire;

[0049] The square permanent magnet 2 is made of neodymium iron boron (model N52), has a length of 4 mm, a width of 1.1 mm, and a height of 0.6 mm, and is placed in the groove at the top of the base of the sensing unit;

[0050] The base 3 is made of white resin, has a length of 4.6 mm, a width of 3 mm, and a height of 2.5 mm, and has a triangular wedge structure at the front end of the cuboid, with a height of 1 mm, a width of 4.6 mm, and an acute angle of 30°; the tail of the base has a groove with a height of 1.45 mm, a length of 3 mm, and a width of 1 mm, and the top of the base has a groove with a height of 0.3 mm, a length of 1.1 mm, and a width of 0.6 mm; there are three through holes for inserting the iron-gallium wire at a height of 1.5 mm on one side of the slope of the cuboid, with a hole spacing of 0.5 mm;

[0051] The cylindrical contact 4 is made of white resin, has a height of 0.8 mm and a diameter of 4 mm, and has a strip-shaped bottom beam with a length of 3 mm, a width of 0.8 mm, and a height of 1.2 mm; there are three holes for inserting the iron-gallium wire at a height of 0.5 mm from the bottom beam, with a hole spacing of 0.5 mm;

[0052] The PDMS pillar 5 is cross-shaped, with a length of 7 mm, a width of 3 mm, and a height of 3 mm; the length refers to the distance between the two corresponding edges of the cross-shaped structure, and the width refers to the length of the edge of one end of the cross-shaped structure;

[0053] The PDMS bump 6 is a square ladder with a height of 1 mm and a side length of 11 mm, and has a 45° chamfer on the edge;

[0054] The iron-gallium wire 7 is composed of Fe 83 Ga 17 , has a diameter of 0.5 mm and a length of 6 mm, and is embedded in the through hole of the base of the sensing unit;

[0055] The PDMS bump and the pillar are both prepared by mixing PDMS main agent and PDMS curing agent in a ratio of 10:1, placing them in a mold, and curing at 80°C for 120 minutes.

[0056] Example 1: Test the relationship between pressure and output voltage of a single sensing unit when static force is applied. The main purpose of this example is to study the input-output relationship of the sensing unit and the sensitivity of static force measurement.

[0057] Test platform setup: The experimental platform includes a digital push-pull force gauge, an angle table, a DC stabilized power supply, a DH-8303 data acquisition card, and a computer. The sensing unit is assembled according to the design requirements, fixed on the angle table, placed on the base of the push-pull force gauge, and the transmission rod of the push-pull force gauge is aligned with the cylindrical contact of the sensing unit. The DC stabilized power supply supplies power to the TMR element, and the output of the TMR element is connected to the data acquisition card.

[0058] Experimental process and results: A digital push-pull force is used to apply a force of 0-5N in the normal direction, and the pressure is applied on the cylindrical contact, causing the iron-gallium wire to deform. Due to the inverse magnetostrictive effect of the iron-gallium wire, the magnetic induction intensity near the iron-gallium wire changes, and the TMR element detects this change and outputs a voltage signal. The output voltage of the sensor unit under different pressures is shown in Figure 5 The output voltage of a single sensing unit and the output voltage of a single sensing unit in the range of 0-5N show a good linear relationship, and the minimum detectable pressure is 0.05N. When the pressure is 5N, the output voltage of a single sensing unit is 1542mV, and the sensitivity of the sensing unit is 308.4mV / N.

[0059] Example 2: Test the relationship between pressure and output voltage of the tactile sensor when static three-dimensional force is applied. The main purpose of this example is to study the input-output relationship of the tactile sensor when measuring three-dimensional force and the sensitivity of static force.

[0060] Test platform setup: The experimental platform includes a digital push-pull force gauge, an angle table, a DC stabilized power supply, a DH-8303 data acquisition card, and a computer. The tactile sensor is assembled according to the design requirements, fixed on the angle table, placed on the base of the push-pull force gauge, and the transmission rod of the push-pull force gauge is aligned with the sensor contact. The DC stabilized power supply supplies power to the TMR element, and the output of the TMR element is connected to the data acquisition card.

[0061] Experimental process and results: By changing the angle of the angle table, the sensor is in a horizontal state, and a normal force of 0-20N is applied by the push-pull force gauge. The PDMS bump applies the normal force on the four sensing units, and the average output voltage of the four units is calculated as shown in Figure 6As shown in the figure, the normal force and the average output voltage show a good linear relationship in the range of 0-20N, and the normal force sensitivity of the tactile sensor is 71.4mV / N; by changing the angle of the angle table, the sensor is in a vertical state, and the push-pull force gauge is used to apply a normal force of 0-10N, and the PDMS bump will apply a tangential force on the four sensing units, and the output voltage difference of the four units in the tangential force direction is calculated, as shown in the figure Figure 7 As shown in the figure, the tangential force and the output voltage difference show a good linear relationship in the range of 0-10N, and the tangential force sensitivity of the tactile sensor is 62.6mV / N. By changing the angle of the angle table, the sensor is in a state with an angle of 60° with the vertical direction and an angle of 0° with the horizontal direction, and the push-pull force gauge is used to apply a force of 0-10N, and the PDMS bump will transmit the force to the four sensing units, and the output voltage of the TMR element of the four sensing units and the calculated tangential force and normal force are as shown in the figure Figure 8 As shown in the figure.

[0062] Experimental Example 3: Test the output voltage curve of the tactile sensor when a dynamic normal force is applied. The main purpose of this example is to study the dynamic test performance of the tactile sensor.

[0063] Test platform construction: The test platform includes a dynamic force applying device, a data acquisition card, a PC, and a DC stabilized power supply. The dynamic force applying device is composed of a signal generator (AFG2021-SC), a power amplifier (MB500VI), and a vibration exciter (MODAL50). The signal generator generates a square wave force signal with a frequency of 6Hz, which is transmitted to the vibration exciter through the power amplifier and acts on the sensor unit. The vibration exciter is equipped with a matching quartz force sensor (Kistler-9173B) at the top, and the force applied to the sensor is monitored through the output of the quartz force sensor, keeping the normal force at 5N. The output of the sensor unit under the action of the square wave force signal is as shown in the figure Figure 9 As shown in the figure, the first output voltage waveform is amplified to obtain Figure 10 As shown in the figure, the first output voltage waveform is amplified to obtain Figure 10 As shown in the figure, the first output voltage waveform is amplified to obtain As shown in the figure, the first output voltage waveform is amplified to obtain

[0064] The software or protocol involved in the present application are all known technologies.

[0065] From the above examples, we can see that the application adopts the TMR element to detect the change of the magnetic field at the end of the iron-gallium wire and converts it into a voltage signal for output, the advantage of the TMR element compared with the Hall element is more sensitive to weak magnetic field change, which can greatly improve the sensitivity of the sensor, and the super-elastic material PDMS is combined with the magnetostrictive sensing unit, which can greatly improve the detection range of the sensor while reducing the volume of the sensor. Compared with the existing three-dimensional force magnetostrictive sensor, the length is reduced by 4mm, the width is reduced by 14mm, the thickness is reduced by 8mm, the normal force range is increased by 6.67 times, the tangential force range is increased by 10 times, the normal force sensitivity is increased by 1.87 times, and the tangential force sensitivity is increased by 1.99 times.

[0066] The details of the application are known.

Claims

1. A three-dimensional force tactile sensor based on iron-gallium alloy, characterized by The sensor comprises a base body and four sensing units; The base body comprises a protrusion and a support; the lower surface of the protrusion is fixedly connected with the upper surface of the support, and the centers of the two are overlapped; the protrusion is shaped as a square step with a square projection; the support is cross-shaped; the four sensing units are divided into two groups, and the two groups are oppositely distributed on the two sides of the base body; Each sensing unit comprises a Fe-Ga wire, a base, a cylindrical contact, a square permanent magnet and a TMR element; the main body of the base is a cuboid, a rectangular slot is formed in one side bottom, and a common-surface ramp is protruded from the middle lower part of the other side; the side surface of the upper part of the ramp is centrally symmetrical and is provided with three circular holes at intervals; three identical Fe-Ga wires are horizontally arranged and parallel distributed, one end of each wire is fixed in the circular hole of the side surface of the base, and the other end is fixed in the circular hole of the bottom beam of the cylindrical contact; the TMR element is fixed in the rectangular slot of the base; the upper surface of the base is provided with a groove, and the square permanent magnet is fixed in the groove, and the N-pole direction of the magnet points to the cylindrical contact; the four cylindrical contacts are respectively fixed on the lower surfaces of the four corners of the protrusion; The cylindrical contact is in the shape of a round sheet, and has a strip-shaped bottom beam in the lower part, the bottom beam is centrally symmetrical and is provided with three circular holes, and the size and interval of the circular holes are the same as those of the circular holes of the base.

2. The three-dimensional force touch sensor based on Fe-Ga alloy according to claim 1, wherein the protrusion is a square step with a height of 0.5-2 mm and a side length of 10-12 mm, and the upper edge has a chamfer with an angle of 40-50°.

3. The three-dimensional force touch sensor based on Fe-Ga alloy according to claim 1, wherein the support is cross-shaped, and has a length of 6-8 mm, a width of 2-4 mm and a height of 2-4 mm. The Fe-Ga wire has a length of 5-8 mm and a diameter of 0.4-0.6 mm. The base has a cuboid main body with a height of 1.5-3.5 mm, a length of 4-6 mm and a width of 2.5-4 mm, and a triangular wedge structure at the front end of the cuboid, the triangular wedge structure has a height of 0.5-1.5 mm, a width of 4-6 mm and an acute angle of 25-35°. The cylindrical contact has a cylindrical main body with a height of 0.5-1.5 mm and a diameter of 3-5 mm, and a strip-shaped bottom beam at the bottom with a length of 2-4 mm, a width of 0.5-1.5 mm and a height of 1-1.5 mm.

4. The three-dimensional force touch sensor based on Fe-Ga alloy according to claim 1, wherein the cylindrical contact and the base are made of resin; The square permanent magnet is made of ferrous boron; The protrusion and the support are made of PDMS.

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