A multifunctional tactile sensor based on capacitive-magnetostrictive

Abstract

The invention discloses a multifunctional tactile sensor based on capacitive magnetostriction, the sensor comprising interdigital electrodes, a substrate, a shielding layer, a contact, an iron gallium wire, a base, a strip permanent magnet, a TMR element, and a printed circuit board; the interdigital electrodes are fixedly arranged on the top surface of the substrate, the shielding layer is fixedly arranged on the bottom surface of the substrate, the shielding layer is directly opposite to the interdigital electrodes, and the projection of the shielding layer in the vertical direction completely covers the interdigital electrodes; a contact, two iron gallium wires, a base, a strip permanent magnet, and a TMR element constitute a magnetic induction unit, and four identical magnetic induction units are arranged between the substrate and the printed circuit board in the form of a 2×2 array; the sensor adopts a highly integrated proximity sense and tactile sense combined perception method to continuously detect non-contact and contact information of an object, which can improve the precision of a manipulator before and after contacting a measured object, and make up for the limitations of a small object distance and an inability to determine the position distance of an obstructed object.

Description

Technical Field

[0001] The invention relates to the technical field of sensors, and in particular to a capacitive-magnetostrictive multifunctional tactile sensor. Background Art

[0002] With the research and development of robot technology, robots can replace humans to complete repetitive and dangerous production activities, and gradually develop towards intelligence and human-machine interaction. Intelligent precision operation has become a research hotspot, and precision sensors for robots will be an important direction for future research. Traditional robot sensing systems basically include visual and tactile sensors. Among them, visual sensors provide orientation capture and object distance information, and tactile sensors provide stress and object hardness, shape and size under contact. In actual application scenarios, there is often a situation where the object distance is small. At this time, the visual sensor is blocked by the manipulator or cannot capture the distance information due to changes in the viewing angle and light, making it difficult to determine the position. At the same time, the robot has not yet touched the object, and the tactile sensor cannot normally obtain object information. At the same time, due to different conversion and detection principles of external stimulus signals, tactile sensors can be divided into: piezoelectric, resistive, capacitive, piezomagnetic, etc. Some tactile sensors have high sensitivity, but most of them have problems such as single detection function, complex structural design, large amount of calculation, and high cost. In order to improve the precision of robot grasping, perceive distance information at smaller object distances, detect multiple information of objects, and achieve accurate identification and classification, it is urgent to design a capacitive-magnetostrictive multifunctional tactile sensor. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art. In view of the problems that the distance information cannot be perceived at a small object distance, the detection function is single, the structural design is complex, the calculation amount is large, and the cost is high, a multifunctional tactile sensor based on capacitance-magnetostriction is proposed. The multifunctional tactile sensor can obtain distance information at a small object distance in both non-contact and contact modes, detect the hardness and relative dielectric constant of the object, and can be installed on a manipulator to enable the manipulator to obtain more information, realize the accurate perception and precise operation of the manipulator on the object to be measured, and further improve the accuracy of the manipulator's grasping.

[0004] The present invention solves the technical problem by adopting the following technical scheme: a capacitive-magnetostrictive multifunctional tactile sensor, characterized in that the sensor comprises interdigital electrodes, a substrate, a shielding layer, a contact, an iron-gallium wire, a base, a strip permanent magnet, a TMR element, and a printed circuit board; the substrate and the printed circuit board have the same size, are arranged parallel and opposite to each other, the interdigital electrodes are fixedly arranged on the top surface of the substrate, the shielding layer is fixedly arranged on the bottom surface of the substrate, the shielding layer is opposite to the interdigital electrodes and its vertical projection completely covers the interdigital electrodes; a contact, two iron-gallium wires, a base, a A strip permanent magnet and a TMR element constitute a magnetic induction unit, and four identical magnetic induction units are arranged between the substrate and the printed circuit board in the form of a 2×2 array; the top of the contact is a cylindrical connection end, and the lower part is a vertical plate connected to the middle of the bottom of the connection end, and two parallel first horizontal mounting holes located at the same height are arranged in the middle of the vertical plate, and the size of the two first horizontal mounting holes matches the size of the iron gallium wire, and the sum of the heights of the connection end and the vertical plate is less than the distance between the substrate and the printed circuit board; the top of the contact is fixedly connected to the bottom surface of the substrate by gluing;

[0005] The base is a plate-like structure with an "L"-shaped cross section, the bottom of which is fixed on the printed circuit board, the horizontal branch of which is arranged toward one side of the contact, and the vertical branch of which is parallel to and directly opposite to the vertical plate of the contact; two second horizontal mounting holes are arranged in parallel and at the same height in the middle of the vertical branch of the base, and the size of the two second horizontal mounting holes matches the size of the iron-gallium wire; the height of the two second horizontal mounting holes is consistent with the height of the two first horizontal mounting holes and the positions are directly opposite, one end of the two iron-gallium wires is respectively fixed in the two first mounting holes on the vertical plate of the contact, and the other end of the two iron-gallium wires is respectively fixed in the two second horizontal mounting holes on the vertical branch of the base; a strip permanent magnet is fixed on the top of the vertical branch of the base, and the strip permanent magnet and the iron-gallium wire are in a vertical state in space; the top surface of the contact is higher than the top of the permanent magnet, and the bottom surface of the contact is higher than the top surface of the horizontal branch of the base;

[0006] The TMR element is arranged on a printed circuit board on a side of the base away from the contact, and the position of the TMR element is opposite to the projection of the two iron-gallium wires in the vertical direction; the TMR element is parallel to the strip permanent magnet, and the pin of the TMR element on the side close to the base is in contact with the base; the TMR element is fixed on the printed circuit board by pin welding;

[0007] The printed circuit board is provided with the positions of the TMR elements of four identical magnetic induction units, and is provided with four welding positions of the TMR elements and ten output terminals; the size of each welding position is the same as the size of the TMR element, and the welding position of each TMR element is composed of five pads, namely, a VCC pad, an NA pad, a SIG1 pad, a GND pad, and a SIG2 pad, and the five pins of each TMR element are respectively welded to the five pads correspondingly; the VCC pads of the four TMR elements are all connected to the first output terminal VCC through printed wires; the GND pads of the four TMR elements are all connected to the tenth output terminal GND through printed wires, and the eight connection terminals of the SIG1 pad and the SIG2 pad of the four TMR elements are respectively connected to the second to the ninth output terminals through printed wires;

[0008] The magnetization direction of the four strip permanent magnets is parallel to the setting direction of the iron gallium wire, and the substrate, contact and base are all made of non-magnetic conductive materials;

[0009] The interdigitated electrode is composed of a left finger-type electrode and a right finger-type electrode which are horizontally crossed on the left and right sides. The left finger-type electrode and the right finger-type electrode are each provided with a terminal. The sensor is connected to the application circuit through the two terminals of the interdigitated electrode and the ten output terminals of the printed circuit board.

[0010] Compared with the prior art, the present invention has the following beneficial effects:

[0011] 1) Compared with the traditional manipulator with single tactile perception, the method of combining proximity and tactile perception with high integration degree is adopted to continuously detect the non-contact and contact information of the object, including distance information and the hardness and relative dielectric constant of the object, which can improve the precision of the manipulator before and after contacting the object to be measured, and make up for the limitations of small object distance and obstructed object that cannot determine the position distance. It can be seen from application scenario 1 that when the object to be measured approaches the multifunctional tactile sensor, the capacitance value will change, and the distance information of the object can be judged; and it can be seen from application scenario 3 that the object can be identified by detecting two kinds of physical information, the hardness and relative dielectric constant of the object, to identify objects with similar hardness but large difference in relative dielectric constant or similar relative dielectric constant but large difference in hardness. The results of the grasping experiment show that plastic blocks, soft rubber blocks and hard rubber blocks can be judged according to the output signal of the multifunctional tactile sensor, which can make the manipulator work more safely and precisely.

[0012] 2) Use interdigital electrodes to detect a variety of information during the grasping process. When non-contact, the capacitance value changes with the distance of the object being measured. When in contact, the capacitance value varies with the relative dielectric constant of the object. The distance and material properties of the object can be obtained during the grasping process.

[0013] 3) Using the iron-gallium wire with high stress sensitivity as the force sensing part, based on the inverse magnetostrictive effect, the pressure signal is converted into a voltage signal through the TMR element, and the hardness of the object is identified according to the different output voltages. Experiments show that the magnetostrictive tactile sensor array has high sensitivity, good real-time performance and excellent dynamics.

[0014] 4) The multifunctional tactile sensor has the advantages of simple circuit structure, high sensitivity, low manufacturing cost, excellent dynamic characteristics, etc., and does not require additional complex signal processing circuits. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0016] Figure 1 The figure is a structural schematic diagram (side view) of an embodiment of a capacitive-magnetostrictive multifunctional tactile sensor according to the present invention.

[0017] Figure 2 The figure is a schematic diagram of the structure of the interdigital electrodes of an embodiment of a capacitive-magnetostrictive multifunctional tactile sensor according to the present invention.

[0018] Figure 3 The present invention is a schematic structural diagram of a shielding layer according to an embodiment of a capacitive-magnetostrictive multifunctional tactile sensor.

[0019] Figure 4 The present invention is a schematic structural diagram of a magnetic induction unit based on an embodiment of a capacitive-magnetostrictive multifunctional tactile sensor.

[0020] Figure 5 This is a printed line layout diagram of a printed circuit board based on an embodiment of a capacitive-magnetostrictive multifunctional tactile sensor of the present invention (in the figure, printed lines of different grayscales are not conductive, which can be achieved by wiring on a multi-layer composite PCB board).

[0021] Figure 6 This is a graph showing the relationship between the distance to the object being measured and the change in output capacitance in application scenario 1 based on a capacitive-magnetostrictive multifunctional tactile sensor of the present invention;

[0022] Figure 7 This is a relationship diagram between the output voltage and pressure of a capacitive-magnetostrictive multifunctional tactile sensor under different pressures in application scenario 2 of the present invention; wherein, Figure 7U1 in the figure represents the relationship between the output voltage and pressure of the magnetic induction unit under different pressures, where the TMR element is set at the U1 welding position of the printed circuit board. Figure 7 U2 in the figure represents the relationship between the output voltage and pressure of the magnetic induction unit under different pressures, where the TMR element is set at the U2 welding position of the printed circuit board. Figure 7 U3 in the figure represents the relationship between the output voltage and pressure of the magnetic induction unit under different pressures, where the TMR element is set at the U3 welding position of the printed circuit board. Figure 7 U4 in FIG. 1 represents a relationship diagram between the output voltage and pressure of a magnetic induction unit in which the TMR element is arranged at the U4 welding position of the printed circuit board under different pressures.

[0023] Figure 8 The present invention is a multifunctional tactile sensor based on a capacitive-magnetostrictive multifunctional tactile sensor, and the output voltage relationship diagram when the manipulator grasps three different objects in application scenario 3 (the convex curve in the figure is the output voltage relationship curve of the four magnetic induction units of the multifunctional tactile sensor, and the concave curve is the output capacitance change curve of the multifunctional tactile sensor); wherein, Figure 8 (a) is the relationship between the output capacitance change and output voltage of the multifunctional tactile sensor when the robot grasps the plastic block. Figure 8 (b) is the relationship between the output capacitance change and output voltage of the multifunctional tactile sensor when the robot grasps the soft rubber block. Figure 8 (c) is a graph showing the relationship between the output capacitance change and output voltage of the multifunctional tactile sensor when the robot grasps a hard rubber block.

[0024] In the accompanying drawings: 1 is an interdigitated electrode, 2 is a substrate, 3 is a shielding layer, 4 is a contact, 5 is an iron gallium wire, 6 is a base, 7 is a strip permanent magnet, 8 is a TMR element, and 9 is a printed circuit board. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] The present invention provides a multifunctional tactile sensor based on capacitive-magnetostrictive, which comprises a forked electrode 1, a substrate 2, a shielding layer 3, a contact 4, an iron-gallium wire 5, a base 6, a strip permanent magnet 7, a TMR element 8, and a printed circuit board 9; the substrate 2 and the printed circuit board 9 have the same size, are parallel and opposite to each other, the forked electrode 1 is fixedly arranged on the top surface of the substrate 2, the shielding layer 3 is fixedly arranged on the bottom surface of the substrate 2, the shielding layer 3 is opposite to the forked electrode 1, and its vertical projection completely covers the forked electrode 1; a contact 4, two iron-gallium wires 5, a base 6, a strip permanent magnet 7, and a TMR element 8 constitute a magnetic induction unit, and four identical magnetic induction units are arranged between the substrate 2 and the printed circuit board 9 in the form of a 2×2 array. The top of the contact 4 is a cylindrical connecting end, and the lower part is a vertical plate connected to the middle of the bottom of the connecting end. Two parallel first horizontal mounting holes located at the same height are arranged in the middle of the vertical plate. The sizes of the two first horizontal mounting holes match the sizes of the iron gallium wire 5. The sum of the heights of the connecting end and the vertical plate is less than the distance between the substrate 2 and the printed circuit board 9. The top of the contact 4 is fixedly connected to the bottom surface of the substrate 2 by means of glue.

[0028] The base 6 is a plate-like structure with an "L"-shaped cross section. Its bottom is fixed on the printed circuit board 9. Its horizontal branch is arranged toward one side of the contact 4, and its vertical branch is parallel to and directly opposite to the vertical plate of the contact 4. Two parallel second horizontal mounting holes at the same height are arranged in the middle of the vertical branch of the base 6. The size of the two second horizontal mounting holes matches the size of the iron gallium wire 5. The height of the two second horizontal mounting holes is consistent with the height of the two first horizontal mounting holes and the positions are directly opposite. One end of the two iron gallium wires 5 is respectively fixed in the two first mounting holes on the vertical plate of the contact 4, and the other end of the two iron gallium wires 5 is respectively fixed in the two second horizontal mounting holes on the vertical branch of the base 6. A strip permanent magnet 7 is fixed on the top of the vertical branch of the base 6, and the strip permanent magnet 7 is vertical to the iron gallium wire 5 in space. The top surface of the contact 4 is higher than the top of the permanent magnet 7, and the bottom surface of the contact 4 is higher than the top surface of the horizontal branch of the base 6.

[0029] The TMR element 8 is disposed on the printed circuit board 9 on the side of the base 6 away from the contact 4, and the position of the TMR element 8 is opposite to the projection of the two iron gallium wires 5 in the vertical direction, the TMR element 8 is parallel to the strip permanent magnet 7, and the pins of the TMR element 8 on the side close to the base 6 are in contact with the base 6. The TMR element 8 is fixed on the printed circuit board 9 by pin welding.

[0030] The printed circuit board 9 is provided with a printed circuit at the position of the TMR elements of four identical magnetic induction units, and is provided with four welding positions of the TMR elements (with reference numerals U1, U2, U3, and U4) and ten output terminals; the size of each welding position is the same as the size of the TMR element, and the welding position of each TMR element is composed of five pads, namely, a VCC pad, an NA pad, a SIG1 pad, a GND pad, and a SIG2 pad, and the five pins of each TMR element are respectively welded to the five pads. The VCC pads of the four TMR elements are all connected to the first output terminal VCC through printed wires; the GND pads of the four TMR elements are all connected to the tenth output terminal GND through printed wires, and the eight terminals of the SIG1 pad and the SIG2 pad of the four TMR elements are respectively connected to the second to ninth output terminals (S1-S8) through printed wires.

[0031] The magnetization direction of the permanent magnet 7 is parallel to the arrangement direction of the iron-gallium wire 5, and the substrate 2, the contact 4, and the base 6 are all made of non-magnetic conductive materials;

[0032] The interdigitated electrode 1 is composed of a left finger-type electrode and a right finger-type electrode which are horizontally crossed on the left and right sides. The left finger-type electrode and the right finger-type electrode are each provided with a terminal. The sensor is connected to the application circuit through the two terminals of the interdigitated electrode 1 and the ten output terminals of the printed circuit board 9.

[0033] The size of the substrate 2 and the printed circuit board 9 is 30mm×25mm. The interdigitated electrode 1 is composed of a left finger-shaped electrode and a right finger-shaped electrode arranged horizontally and crossed on the left and right sides. The left finger-shaped electrode and the right finger-shaped electrode are each provided with a terminal. Each finger-shaped electrode is connected by three horizontal long strip branches and a vertical long strip branch. The size of the horizontal long strip branch is 25mm×2mm, and the size of the vertical long strip branch is 1mm×23mm. The three horizontal long strip branches of the left finger-shaped electrode are connected to the left side of the corresponding vertical long strip branch at the same spacing from top to bottom, and the top of the uppermost horizontal long strip branch is flush with the top of the corresponding vertical long strip branch. The spacing between two horizontal strip branches is 6mm; the three horizontal strip branches of the right finger electrode are connected to the middle of the right side of the corresponding vertical strip branch with the same spacing from top to bottom, the spacing between the two horizontal strip branches is 6mm, and the distance between the upper edge of the top horizontal strip branch and the top of the vertical strip branch is 4mm; the left finger electrode and the right finger electrode are arranged in a way that the tops of their vertical strip branches are aligned, and the distance between the right side of the top horizontal strip branch of the left finger electrode and the left side of the vertical strip branch of the right finger electrode is 1mm. The lower ends of the vertical strip branches of the left finger electrode and the right finger electrode are the connection terminals of the interdigital electrode 1.

[0034] The size of the shielding layer 3 located on the back of the substrate is 29mm×24mm; the length, width and spacing of the interdigitated electrodes are parameter values ​​obtained through simulation design optimization. The interdigitated electrodes are connected by wires and connected to the impedance analyzer. The approach distance of the object under test and the relative dielectric constant of the object are judged by the output capacitance change value; the shielding layer plays a shielding role on the back of the substrate 2, blocking the electric field on the back of the interdigitated capacitance sensor, so that it has better anti-interference ability.

[0035] The length of the Fe-Gallium wire is 8-10 mm and the diameter is 0.5-0.8 mm. The Fe-Gallium wire 5 is 8 mm long and 0.8 mm in diameter. It is made by a combination of forging, hot rolling, cold and hot drawing, and is recrystallized into equiaxed grains by current heat treatment, i.e., rapid heating followed by short-time annealing, to enhance the piezomagnetic effect of the Fe-Gallium wire 5 and optimize its magnetic properties. The saturation magnetostriction coefficient of the Fe-Gallium wire is 200×10 -6 , the saturation magnetization is 1.43×10 6 A / m, the domain wall interaction coefficient is 0.001, and the hysteresis-free magnetization intensity shape factor is 7012A / m.

[0036] The TMR element 8 is 3 mm long, 3 mm wide, and 1.45 mm thick, and its model is TMR2003. TMR2003 has excellent performance and is packaged in SOT23-5.

[0037] The cylindrical body of the contact 4 has a diameter of 4 mm and a thickness of 1 mm; the vertical plate has a length of 3 mm, a thickness of 1.5 mm, and a height of 2.1 mm; the two first horizontal mounting holes on the vertical plate have a diameter of 0.8 mm and a length of 1.5 mm, and are 0.5 mm from the bottom surface of the vertical plate; the center distance between the two first horizontal mounting holes is 1.5 mm, which is compatible with the iron gallium wire 5;

[0038] The base 6 is 4mm long, 4mm wide, and 2.5mm high. The second horizontal mounting hole on its vertical branch has a diameter of 0.8mm, a length of 2mm, and a distance of 1mm from the bottom surface of the base. The center distance between the two second horizontal mounting holes is 1.5mm. The horizontal branch of the base 6 is 2mm long, 4mm wide, and 0.6mm high, which is used to enhance the stability of the unit when subjected to pressure. In this embodiment, the contact 4 and the base 6 are made of resin.

[0039] The strip permanent magnet 7 is a strip permanent magnet with a length of 4 mm, a width of 1 mm, and a thickness of 0.6 mm. It is made of neodymium iron boron and is fixed with glue in the middle of the top surface of the vertical branch of the base 6, 0.5 mm away from the right edge of the base. The magnetization directions of the four strip permanent magnets 7 are all in the X-axis direction (parallel to the setting direction of the iron gallium wire), providing the iron gallium wire with a uniform bias magnetic field of 830 Gs; the top surface of the contact 4 is 0.5 mm higher than the top of the permanent magnet 7, and the bottom surface of the contact 4 is 0.5 mm higher than the top surface of the horizontal branch of the base 6, ensuring that the unit contact does not contact the plane of the base when it is under pressure, and also ensuring that the interdigital capacitance sensor does not contact the permanent magnet.

[0040] Four TMR components are soldered on the surface of the printed circuit board in a 2×2 arrangement. The center distance between the left and right TMR components in the length direction is 16 mm, and the center distance between the front and rear TMR components in the width direction is 10 mm.

[0041] The soldering positions of the four TMR elements are marked as U1, U2, U3 and U4 in the figure, and the 10 output terminals are marked as 10-19 in order from left to right. The center point of the soldering position U4 is 3 mm away from the nearest width edge of the printed circuit board and 5 mm away from the nearest length edge of the printed circuit board, that is, the center point of one of the TMR elements is 3 mm away from the nearest width edge of the printed circuit board and 5 mm away from the nearest length edge of the printed circuit board.

[0042] The working principle of the multifunctional tactile sensor is as follows: based on the fringe electric field effect and the inverse magnetostrictive effect, when an object is detected to be close or in contact, the mixed relative dielectric constant changes; when subjected to pressure, the arrangement of the magnetic domains inside the iron-gallium wire changes, which in turn causes the surrounding magnetic induction intensity to change. This change can be detected by the TMR element and outputs a voltage signal to achieve force measurement. The multifunctional tactile sensor can work in both non-contact and contact modes, obtain distance information when the object distance is relatively small, detect the hardness and relative dielectric constant of the object, and can be installed on the manipulator to enable the manipulator to obtain more information, realize the manipulator's accurate perception and precise operation of the object to be measured, and further improve the accuracy of the manipulator's grasping.

[0043] According to the specific size specifications described above, a multifunctional tactile sensor based on capacitive-magnetostrictive is obtained in an embodiment, and a relevant experimental platform is built to test the multifunctional tactile sensor to fully illustrate the feasibility and progress of the present invention. The specific test experiment process is shown in test application scenarios 1-3. It should be noted that the software or protocols involved in application scenarios 1-3 are all well-known technologies.

[0044] Application scenario 1: When a rectangular rubber block approaches a multifunctional tactile sensor at a distance of 0-4 mm, the relationship between the output capacitance change and the distance.

[0045] The main purpose of this application scenario is to study the relationship between the change in output capacitance of the multifunctional tactile sensor and the distance when an object approaches.

[0046] Experimental platform construction: The experimental platform consists of an impedance analyzer, a digital push-pull force gauge and a measured object. The measured object is a rectangular rubber block. The multifunctional tactile sensor is fixed on the experimental table. The digital push-pull force gauge displays the distance between the multifunctional tactile sensor and the measured object. The impedance analyzer measures the output capacitance value of the multifunctional tactile sensor.

[0047] Experimental process and results: When the rectangular rubber block approaches the multifunctional tactile sensor, the relationship curve between the output capacitance change and the distance at a distance of 0-4mm is obtained, as shown in Figure 6 As shown in the figure, since the relative dielectric constant of the object material is different from that of air, when the detection object approaches, the mixed relative dielectric constant changes, and different capacitance changes will be obtained.

[0048] Application scenario 2: The relationship between force and output voltage of a multifunctional tactile sensor under a pressure of 0-16N.

[0049] The main purpose of this application scenario is to study the pressure-voltage relationship and sensitivity of the multifunctional tactile sensor.

[0050] Experimental platform construction: The experimental platform consists of a DC regulated power supply, a data acquisition card, a digital push-pull force gauge and a computer. The multifunctional tactile sensor unit is fixed on the experimental table, the digital push-pull force gauge applies static force to the multifunctional tactile sensor, the DC regulated power supply is powered, and the data acquisition card collects the output voltage and transmits it to the computer.

[0051] Experimental process and results: A digital push-pull force gauge was used to apply a pressure of 0-16N to the multifunctional tactile sensor. The output voltage under different pressures was as follows: Figure 7 As shown, the results show that the force on the magnetic induction unit is relatively uniform, the maximum relative error does not exceed 3%, the unit output voltage increases with the increase of pressure, and under a static pressure of 0-4N, the multifunctional tactile sensor can return to its initial position after the force ends, with good repeatability and stability. When the pressure is 4N, the maximum output voltage of the unit is 612.25mV, and the sensitivity is 153.63mV / N, with excellent performance.

[0052] Application scenario 3: Install the multifunctional tactile sensor on the inner surface of the fingers of the three-finger manipulator, and use the computer to control the grasping speed and displacement distance of the manipulator to keep it consistent during multiple grasping processes, and grasp rectangular objects with the same mass but different hardness and relative dielectric constants.

[0053] Experimental platform construction: The experimental platform consists of a manipulator, a DC regulated power supply, a data acquisition card, an impedance analyzer, a computer and the object to be measured. The multifunctional tactile sensor is fixed on the manipulator, the DC regulated power supply is powered, the data acquisition card collects the output voltage and transmits it to the computer, and the impedance analyzer measures the output capacitance value.

[0054] Experimental process and results: The grasping speed and displacement distance of the three-finger manipulator were adjusted so that the multifunctional tactile sensor installed on the inner surface of the manipulator's fingers could completely adhere to the surface of the object being measured after grasping. When the manipulator grasped multiple objects, the output voltage and output capacitance changes of each magnetic induction unit of the multifunctional tactile sensor were as follows: Figure 8 As shown. By comparing the data in the figure, when grabbing a plastic block, the average output voltage is 362.27mV, and the capacitance change is 0.35; when grabbing a soft rubber block, the average output voltage is 200.52mV, and the capacitance change is 0.37; when grabbing a hard rubber block, the average output voltage is 355.45mV, and the capacitance change is 0.76. By using the two types of object information, hardness and relative dielectric constant, we can distinguish between plastic blocks, soft rubber blocks, and hard rubber blocks. The hardness of plastic blocks and hard rubber blocks is similar, but the relative dielectric constant is different; the relative dielectric constant of plastic blocks and soft rubber blocks is similar, but the hardness is different. The two types of information can be used for accurate identification and classification.

[0055] Any matters not described in the present invention are applicable to the prior art.

Claims

1. A multifunctional tactile sensor based on capacitive-magnetostrictive, It is characterized in that The sensor comprises interdigital electrodes, a substrate, a shielding layer, a contact, an iron-gallium wire, a base, a strip permanent magnet, a TMR element, and a printed circuit board; the substrate and the printed circuit board have the same size, are parallel and opposite to each other, the interdigital electrodes are fixedly arranged on the top surface of the substrate, the shielding layer is fixedly arranged on the bottom surface of the substrate, the shielding layer is opposite to the interdigital electrodes, and its vertical projection fully covers the interdigital electrodes; a contact, two iron-gallium wires, a base, a strip permanent magnet, and a TMR element constitute a magnetic induction unit, and four identical magnetic induction units are arranged between the substrate and the printed circuit board in the form of a 2×2 array; the top of the contact is a cylindrical connecting end, and the bottom of the contact is a vertical plate connected to the middle of the bottom of the connecting end, and two parallel first horizontal mounting holes at the same height are arranged in the middle of the vertical plate, the size of the two first horizontal mounting holes matches the size of the iron-gallium wire, and the sum of the heights of the connecting end and the vertical plate is less than the distance between the substrate and the printed circuit board; the top of the contact is fixedly connected to the bottom surface of the substrate by gluing; The base is a plate-like structure with an "L"-shaped cross section, the bottom of which is fixed on the printed circuit board, the horizontal branch of which is arranged toward one side of the contact, and the vertical branch of which is parallel to and directly opposite to the vertical plate of the contact; two second horizontal mounting holes are arranged in parallel and at the same height in the middle of the vertical branch of the base, and the size of the two second horizontal mounting holes matches the size of the iron-gallium wire; the height of the two second horizontal mounting holes is consistent with the height of the two first horizontal mounting holes and the positions are directly opposite, one end of the two iron-gallium wires is respectively fixed in the two first mounting holes on the vertical plate of the contact, and the other end of the two iron-gallium wires is respectively fixed in the two second horizontal mounting holes on the vertical branch of the base; a strip permanent magnet is fixed on the top of the vertical branch of the base, and the strip permanent magnet and the iron-gallium wire are in a vertical state in space; the top surface of the contact is higher than the top of the permanent magnet, and the bottom surface of the contact is higher than the top surface of the horizontal branch of the base; The TMR element is arranged on a printed circuit board on a side of the base away from the contact, and the position of the TMR element is opposite to the projection of the two iron-gallium wires in the vertical direction; the TMR element is parallel to the strip permanent magnet, and the pin of the TMR element on the side close to the base is in contact with the base; the TMR element is fixed on the printed circuit board by pin welding; The printed circuit board is provided with the positions of the TMR elements of four identical magnetic induction units, and is provided with four welding positions of the TMR elements and ten output terminals; the size of each welding position is the same as the size of the TMR element, and the welding position of each TMR element is composed of five pads, namely, a VCC pad, an NA pad, a SIG1 pad, a GND pad, and a SIG2 pad, and the five pins of each TMR element are respectively welded to the five pads correspondingly; the VCC pads of the four TMR elements are all connected to the first output terminal VCC through printed wires; the GND pads of the four TMR elements are all connected to the tenth output terminal GND through printed wires, and the eight connection terminals of the SIG1 pad and the SIG2 pad of the four TMR elements are respectively connected to the second to the ninth output terminals through printed wires; The magnetization direction of the four strip permanent magnets is parallel to the setting direction of the iron gallium wire, and the substrate, contact and base are all made of non-magnetic conductive materials; The interdigitated electrode is composed of a left finger-type electrode and a right finger-type electrode which are horizontally crossed on the left and right sides. The left finger-type electrode and the right finger-type electrode are each provided with a terminal. The sensor is connected to the application circuit through the two terminals of the interdigitated electrode and the ten output terminals of the printed circuit board.

2. A capacitive-magnetostrictive multifunctional tactile sensor according to claim 1, It is characterized in that The interdigitated electrode is composed of a left finger-type electrode and a right finger-type electrode which are horizontally crossed on the left and right sides. The left finger-type electrode and the right finger-type electrode are each provided with a connection terminal. Each finger-type electrode is composed of three horizontal long strip branches connected with a vertical long strip branch; the three horizontal long strip branches of the left finger-type electrode are connected to the left side of the corresponding vertical long strip branch at the same interval from top to bottom, and the top of the uppermost horizontal long strip branch is flush with the top of the corresponding vertical long strip branch; the three horizontal long strip branches of the right finger-type electrode are connected to the middle of the right side of the corresponding vertical long strip branch at the same interval from top to bottom; the left finger-type electrode and the right finger-type electrode are arranged in a manner that the top ends of the vertical long strip branches of the two are aligned; the lower ends of the vertical long strip branches of the left finger-type electrode and the right finger-type electrode are the connection terminals of the interdigitated electrode.

3. The multifunctional capacitive-magnetostrictive tactile sensor according to claim 2, It is characterized in that The size of the horizontal strip branches of the left finger-shaped electrode and the right finger-shaped electrode is 25mm×2mm, and the size of the vertical strip branches is 1mm×23mm; the spacing between the two horizontal strip branches of the left finger-shaped electrode is 6mm; the spacing between the two horizontal strip branches of the right finger-shaped electrode is 6mm, and the distance between the upper edge of the uppermost horizontal strip branch and the top of the vertical strip branch is 4mm; the distance between the right side of the uppermost horizontal strip branch of the left finger-shaped electrode and the left side of the vertical strip branch of the right finger-shaped electrode is 1mm.

4. The multifunctional tactile sensor based on capacitive-magnetostrictive according to claim 1, It is characterized in that The size of the substrate and the printed circuit board is 30 mm×25 mm; the size of the shielding layer located on the back of the substrate is 29 mm×24 mm.

5. The multifunctional capacitive-magnetostrictive tactile sensor according to claim 1, It is characterized in that The length of the iron gallium wire is 8 mm and the diameter is 0.8 mm.

6. The multifunctional capacitive-magnetostrictive tactile sensor according to claim 1, It is characterized in that The TMR element is 3 mm long, 3 mm wide, and 1.45 mm thick, and is packaged in SOT23-5.

7. The multifunctional capacitive-magnetostrictive tactile sensor according to claim 1, It is characterized in that The diameter of the cylinder of the contact is 4mm, the thickness is 1mm, the length of the vertical plate is 3mm, the thickness is 1.5mm, and the height is 2.1mm. The diameter of the two first horizontal mounting holes on the vertical plate is 0.8mm, the length is 1.5mm, the distance from the bottom surface of the vertical plate is 0.5mm, and the center distance between the two first horizontal mounting holes is 1.5mm.

8. The multifunctional capacitive-magnetostrictive tactile sensor according to claim 1, It is characterized in that The base is 4mm long, 4mm wide and 2.5mm high. The second horizontal mounting hole on its vertical branch has a diameter of 0.8mm, a length of 2mm, a distance of 1mm from the bottom surface of the base, and a center distance of 1.5mm between the two second horizontal mounting holes. The horizontal branch of the base is 2mm long, 4mm wide and 0.6mm high.

9. The multifunctional capacitive-magnetostrictive tactile sensor according to claim 1, It is characterized in that The strip permanent magnet has a length of 4 mm, a width of 1 mm, a thickness of 0.6 mm, and is made of neodymium iron boron.

10. The multifunctional capacitive-magnetostrictive tactile sensor according to claim 1, It is characterized in that Four TMR components are soldered on the surface of the printed circuit board in a 2×2 arrangement. The center distance between the left and right TMR components in the length direction is 16 mm, and the center distance between the front and rear TMR components in the width direction is 10 mm; the center point of one of the TMR components is 3 mm away from the nearest width edge of the printed circuit board, and 5 mm away from the nearest length edge of the printed circuit board.

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