Compression-torsion tactile sensor and method of making

Abstract

Disclosed are a compression-torsion tactile sensor and a preparation method thereof. In the sensor, an upwardly protruding sensor base inner locking ring is arranged on the upper surface of a sensor base body; a Hall element is nested in the sensor base body; a magnet framework includes a cylinder arranged below and a plate structure located at the top of the cylinder, a groove is arranged in the cylinder, the periphery of the plate structure is provided with an embedded protrusion, the cylinder is locked and connected with the sensor base inner locking ring to avoid interference from tangential force; a magnet is arranged in the groove; a flexible resin sensing layer is provided with a positioning groove for matching the embedded protrusion, so as to connect the flexible resin sensing layer with the magnet framework; a silicon rubber elastomer is nested in the sensor base body and is bonded between the flexible resin sensing layer and the sensor base body, so as to compress or twist based on the external force or torque transmitted by the flexible resin sensing layer, so that the spatial position of the magnet framework changes, and the magnet moves up and down and rotates, and an RTV anti-skid layer is connected to the flexible resin sensing layer.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tactile sensing, in particular to a compression-torsion tactile sensor and a preparation method. BACKGROUND

[0002] Multi-dimensional force tactile sensor plays an important role in the process of robot perceiving the world, flexible manipulation, performing complex tasks and interacting with people, and is an indispensable part of robot intelligence and humanization. At present, tactile sensors are mainly divided into resistance type, capacitance type, piezoelectric type and photosensitive type according to principle. The above forms of sensors are usually sensitive to pressure measurement only, and it is difficult to measure the torsion of the sensor interface.

[0003] The information disclosed in the background section merely serves to enhance the understanding of the background of the present application, and therefore can contain information that is not prior art known to those of ordinary skill in the art. SUMMARY

[0004] In view of the deficiencies or defects of the prior art, a compression-torsion tactile sensor and a preparation method are provided. Under the action of external force, the annular silicone rubber elastomer is compressed or twisted, so that the spatial position of the rectangular magnet embedded in the sensor skeleton structure changes, thereby causing the change of the spatial magnetic field. The change of the magnetic field is detected by the planar Hall element, the magnetic field change is converted into a voltage signal output, and the corresponding relationship between the pressure and the torque size and the voltage is established to realize the sensor detection of the pressure and the torque. The sensor has natural advantages in torque measurement, and can simulate human skin to realize dynamic and static force measurement.

[0005] The purpose of the present application is achieved by the following technical solutions.

[0006] A compression-torsion tactile sensor comprises,

[0007] A sensor base body, the upper surface of which is provided with a sensor base inner locking ring protruding upward;

[0008] A Hall element, which is nested in the sensor base body,

[0009] A magnet skeleton, which comprises a cylinder provided below and a plate structure located at the top of the cylinder, the cylinder is provided with a groove, the periphery of the plate structure is provided with an embedded protrusion, and the cylinder is locked and connected with the sensor base inner locking ring to avoid interference from tangential force;

[0010] A magnet, which is provided in the groove;

[0011] A flexible resin sensing layer, which is provided with a positioning groove for matching the embedded protrusion, so as to connect the flexible resin sensing layer and the magnet skeleton;

[0012] A silicon rubber elastomer is nested in the sensor base body and bonded between the flexible resin sensing layer and the sensor base body to compress or twist based on the external force or torque transmitted by the flexible resin sensing layer, so that the spatial position of the magnet skeleton changes and the magnet moves up and down and rotates,

[0013] An RTV anti-skid layer is connected to the flexible resin sensing layer.

[0014] In the pressure and torque tactile sensor, the Hall element is a planar Hall element.

[0015] In the pressure and torque tactile sensor, the silicon rubber elastomer is in a ring structure.

[0016] In the pressure and torque tactile sensor, the surface of the Hall element is provided with an anti-skid coating.

[0017] In the pressure and torque tactile sensor, the magnet is an axisymmetric magnet.

[0018] In the pressure and torque tactile sensor, the Hall element is used to convert the change of the three-dimensional magnetic field perpendicular to the plane into a voltage signal, and the Hall element is connected to a data acquisition card to transmit the voltage signal to a computer to obtain the size and direction of the pressure and torque.

[0019] In the pressure and torque tactile sensor, a first straight line passing through the center of the magnet and perpendicular to the upper surface of the magnet is parallel to a second straight line passing through the center of the Hall element and perpendicular to the upper surface of the Hall element, and the Hall element is a center-symmetric structure.

[0020] In the pressure and torque tactile sensor, the magnet is a rectangular magnet.

[0021] In the pressure and torque tactile sensor, the RTV anti-skid layer, the flexible resin sensing layer, the magnet skeleton and the silicon rubber elastomer share a common central axis.

[0022] The preparation method of the pressure and torque tactile sensor comprises the following steps:

[0023] The sensor base body, the RTV anti-skid layer, the flexible resin sensing layer, the magnet skeleton and the silicon rubber elastomer of the pressure and torque tactile sensor are prepared based on 3D printing technology;

[0024] The magnet is embedded in the magnet skeleton, coated with flexible resin for packaging, and cured again in a UV curing box, and the cylinder is locked and connected to the locking ring in the sensor base to avoid interference from tangential force;

[0025] The Hall element is pasted on the circuit board and nested in the sensor base body;

[0026] The RTV anti-skid layer is scraped on the flexible resin sensing layer, and cured at room temperature, and the positioning groove of the flexible resin sensing layer is matched with the embedded convex to connect the flexible resin sensing layer and the magnet framework,

[0027] The silicon rubber elastomer is nested in the sensor base body and is bonded between the flexible resin sensing layer and the sensor base body to compress or twist based on the external force or torque transmitted by the flexible resin sensing layer, so that the spatial position of the magnet framework changes, and the magnet generates up-down movement and rotation.

[0028] Compared with the prior art, the present application has the following beneficial effects:

[0029] The present application can convert the received external pressure and torque into a voltage signal, and detect the size and direction of the contact force or torque by judging the size and shape characteristics of the voltage change, so as to achieve the purpose of detecting the contact pressure and torque, and can realize an ultra-high torque and angle resolution of 0.2 and 0.1°, and a range of more than 150 , by designing the size of the annular elastomer, such as reducing the cross-sectional area of the ring or increasing the length of the beam, so that the overall elastic modulus becomes smaller and is more prone to displacement under external force. Simple to make, short production cycle and extremely low cost. At the same time, the designability of the sensor is strong. Through material technology, the production of different flexible matrix structures is realized, which greatly shortens the design and verification period, and the range of the sensor can be further controlled by controlling the curing ratio. Compared with other types of pressure and torque sensors, the magnetic sensor has natural advantages in three-dimensional force measurement, and can simulate human skin to realize dynamic and static force measurement.

[0030] The description is only a summary of the technical solutions of the present application, in order to make the technical means of the present application more clear and understandable, to the extent that the contents of the description can be implemented by those skilled in the art, and in order to make the said and other purposes, features and advantages of the present application more obvious and easy to understand, the following specific embodiments of the present application are exemplified. BRIEF DESCRIPTION OF DRAWINGS

[0031] Various other advantages and benefits of the present application will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The accompanying drawings are for purposes of illustrating the preferred embodiments and are not intended to limit the present application. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained from these drawings without creative labor for those of ordinary skill in the art. Moreover, the same reference numerals are used to represent the same parts throughout the drawings.

[0032] In the drawings:

[0033] Figure 1 This is a schematic diagram of the structure of the present invention;

[0034] Figure 2 This is an exploded structural diagram of the present invention;

[0035] Figure 3 This is a schematic diagram of the pressure signal change according to the present invention;

[0036] Figure 4 This is a schematic diagram of the torque signal variation according to the present invention.

[0037] The present invention will be further explained below with reference to the accompanying drawings and embodiments. Detailed Implementation

[0038] Specific embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While specific embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0039] It should be noted that certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that different terms may be used to refer to the same component. This specification and claims do not distinguish components based on differences in terminology, but rather on differences in function. The terms "comprising" or "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising but not limited to." The following descriptions are preferred embodiments for carrying out the invention; however, these descriptions are for the purpose of understanding the general principles of the specification and are not intended to limit the scope of the invention. The scope of protection of this invention is determined by the appended claims.

[0040] To facilitate understanding of the embodiments of the present invention, the following will provide further explanation and description with reference to the accompanying drawings and several specific embodiments, and the accompanying drawings do not constitute a limitation on the embodiments of the present invention.

[0041] To better understand, such as Figures 1 to 4 As shown, a pressure-torsion tactile sensor includes,

[0042] The sensor base body 10 has an upwardly protruding sensor base inner locking ring 9 on its upper surface;

[0043] Hall element 7, which is nested in sensor base body 10,

[0044] Magnet skeleton 5, including a cylinder with a groove in it and a plate structure on the top of the cylinder, the plate structure has a fitting protrusion 4 on its periphery, the cylinder is locked to the locking ring 9 in the sensor base to avoid being disturbed by tangential force;

[0045] Magnet 6, which is in the groove;

[0046] Flexible resin sensing layer 3, which has a positioning groove 2 to fit the fitting protrusion 4, to connect the flexible resin sensing layer 3 and the magnet skeleton 5;

[0047] Silicone elastomer 8, which is nested in the sensor base body 10 and bonded between the flexible resin sensing layer 3 and the sensor base body 10 to compress or twist based on the external force or torque transmitted by the flexible resin sensing layer 3, so that the spatial position of the magnet skeleton 5 changes, and the magnet moves up and down and rotates,

[0048] RTV anti-slip layer 1, which is connected to the flexible resin sensing layer 3.

[0049] In the preferred embodiment of the pressure and torque tactile sensor, the Hall element 7 is a planar Hall element 7.

[0050] In the preferred embodiment of the pressure and torque tactile sensor, the silicone elastomer 8 is in a ring structure.

[0051] In the preferred embodiment of the pressure and torque tactile sensor, the surface of the Hall element 7 is provided with an anti-slip coating.

[0052] In the preferred embodiment of the pressure and torque tactile sensor, the magnet 6 is an axisymmetric magnet.

[0053] In the preferred embodiment of the pressure and torque tactile sensor, the Hall element 7 is used to convert the change of the three-dimensional magnetic field perpendicular to the plane into a voltage signal, and the Hall element 7 is connected to a data acquisition card to transmit the voltage signal to a computer to obtain the size and direction of the pressure and torque.

[0054] In the preferred embodiment of the pressure and torque tactile sensor, the first straight line passing through the center of the magnet and perpendicular to the upper surface of the magnet is parallel to the second straight line passing through the center of the Hall element 7 and perpendicular to the upper surface of the Hall element 7, and the Hall element 7 is a center-symmetric structure.

[0055] In the preferred embodiment of the pressure and torque tactile sensor, the magnet 6 is a rectangular magnet.

[0056] In the preferred embodiment of the pressure and torque tactile sensor, the RTV anti-slip layer 1, the flexible resin sensing layer 3, the magnet skeleton 5, and the silicone elastomer 8 have a common central axis.

[0057] The method for preparing the pressure-torque tactile sensor comprises the following steps:

[0058] The sensor base body 10, the RTV anti-skid layer 1, the flexible resin sensing layer 3, the magnet skeleton 5 and the silicone elastomer 8 of the pressure-torque tactile sensor are prepared based on the 3D printing technology;

[0059] The magnet is embedded in the magnet skeleton 5, the flexible resin is coated for packaging, and the cylinder is locked and connected to the inner locking ring 9 of the sensor base to avoid interference from the tangential force;

[0060] The Hall element 7 is pasted on the circuit board and nested in the sensor base body 10;

[0061] The RTV anti-skid layer 1 is scraped and coated on the flexible resin sensing layer 3, and cured at room temperature, and the positioning groove 2 of the flexible resin sensing layer 3 is matched with the embedded convex 4 to connect the flexible resin sensing layer 3 and the magnet skeleton 5,

[0062] The silicone elastomer 8 is nested in the sensor base body 10 and bonded between the flexible resin sensing layer 3 and the sensor base body 10 to compress or twist based on the external force or torque transmitted by the flexible resin sensing layer 3, so that the spatial position of the magnet skeleton 5 changes and the magnet moves up and down and rotates.

[0063] In one embodiment, the RTV anti-skid layer 1 and the flexible resin sensing layer 3 are connected to each other, the inside of the flexible resin sensing layer 3 is provided with a positioning groove for connection with the magnet skeleton 5. The outside of the magnet skeleton 5 is provided with an embedded convex 4 for connection and positioning with the flexible resin sensing layer 3. The inside of the magnet skeleton 5 is provided with a groove for storing the magnet.

[0064] In one embodiment, the silicone elastomer 8 is nested directly above the sensor base; the magnet skeleton 5 and the sensor base are nested with each other, only allowing the sensor to sense the change of pressure and torque, and the flexible matrix structure deforms under the action of external force, so that the relative spatial position of the magnet and the Hall element 7 changes; the Hall element 7 senses the component of the three-dimensional space magnetic flux density perpendicular to the Hall plane, and the measurement of pressure and torque is realized according to the electric signal generated by the Hall element 7.

[0065] In one embodiment, the center of the magnet and the center of the Hall element 7 exhibit the characteristics of mutual bias in space, and the silicone elastomer 8 deforms under the action of external force, so that the relative spatial position of the magnet and the Hall element 7 changes.

[0066] In one embodiment, the pressure-torque tactile sensor can convert the external force / torque received into a voltage signal, and detect the size and direction of the contact force / torque by judging the size and shape characteristics of the voltage change, so as to achieve the purpose of detecting the contact force / torque. The sensor has good resolution.

[0067] In one embodiment, the Hall element 7 is used to perceive the component of the three-dimensional space magnetic flux density perpendicular to the Hall plane, and the multi-dimensional force measurement is realized according to the Hall voltage generated by the Hall element 7.

[0068] As preferred, the magnet is a rectangular magnet. The rectangular magnet is used to generate a three-dimensional anisotropic magnetic field, and the magnetic field distribution characteristics are similar to the shape of the rectangular magnet. The magnetic flux density decreases quickly along the short side direction of the magnet, and decreases slowly along the long side direction of the magnet, which guarantees the anisotropy of the output voltage of the Hall element 7 moving along the x-axis and the y-axis. Compared with the circular central symmetric magnet, the signal voltage changes are the same when the Hall element 7 moves in different directions, and it is difficult to distinguish the movement direction.

[0069] In one embodiment, the Hall element 7 is used to convert the change of the three-dimensional magnetic field perpendicular to the plane magnetic flux density component into an electrical signal output. The voltage signal is transmitted to the computer through the data acquisition card to obtain the size and direction of the force / torque.

[0070] In one embodiment, the RTV anti-skid layer 1 can increase the friction coefficient of the object surface, prevent torsional slip from occurring when contacting the object, and thus cause inaccurate torque measurement. The flexible resin sensing layer 3 can well guarantee the contact with the outside world and better transmit the contact force to the intermediate silicone elastomer 8. At the same time, the flexible resin layer has a structure similar to human fingerprints, greatly increases the area of the RTV anti-skid layer, and thus guarantees that the coating does not fall off. The flexible resin layer is provided below with annularly distributed positioning grooves 2, which are connected with the embedding protrusions 4 of the magnet skeleton. The magnet skeleton 5 is designed with a groove below, which facilitates embedding the magnet. The magnetic sensitive element used is a planar Hall element 7, which can convert the change of the space magnetic flux density perpendicular to the RTV anti-skid layer 1 into an electrical signal output. The planar Hall element is different from the three-dimensional Hall element, which can only detect the single-direction magnetic flux component perpendicular to the surface.

[0071] The intermediate annular silicone elastomer can convert the external force or torque into the up-down movement and rotation of the magnet space position, so as to realize the displacement in the positive pressure direction and the change of the torsion angle of the torque along the pressure direction. The inner locking ring 9 of the sensor base body is locked with the magnet skeleton 5, which guarantees that it is not disturbed by the tangential force. The silicone elastomer 8 in the middle of the sensor can be nested in the sensor base body 10 of the sensor.

[0072] The twist pressure sensor is calibrated using Cartesian coordinate system, and can be subjected to different directions and different sizes of torque and pressure. When the flexible resin sensing layer 3 is subjected to external force / torque, it can transmit pressure to the entire annular silicone elastomer 8, which produces corresponding compression and torsion according to the external force / torque received.

[0073] According to the different forces / torques, the flexible resin sensing layer 3 produces different displacement changes, while driving the magnet skeleton 5 to produce spatial displacement. When the spatial position of the magnet skeleton 5 changes, the spatial position of the rectangular magnet 6 also changes accordingly.

[0074] The planar Hall element 7 changes with the detection of the magnetic field, and the output voltage also changes. In the initial state, the rectangular magnet 6 and the planar Hall element 7 are relatively offset by a certain distance in space. According to the voltage change shape characteristics and the voltage change size, the direction and size of the force / torque can be judged.

[0075] The "force-magnetic-electric" conversion process is completed. The single voltage signal is collected into the computer through the oscilloscope or data acquisition card, and the size and direction of the force / torque received on the flexible resin sensing layer 3 are solved according to the corresponding algorithm.

[0076] The specific collection process is to directly collect the voltage value through the AD conversion module of the single-chip microcomputer, convert the analog quantity into digital quantity transmission, and convert the digital quantity into analog quantity display in the computer. According to the signal characteristics corresponding to different loading modes, the signal characteristics are as follows. When the tangential load is applied along the Z-axis in the positive direction, the sensor can convert the external force into the spatial displacement of the magnet relative to the Hall element. When the spatial positions of the two change, a voltage waveform with fixed characteristics is output. As shown in Figure 3 When a load of about 50N is applied, the sensor outputs a voltage change of about 300mV. When the twist is applied along the Z-axis, the sensor can convert the external force into the spatial displacement of the magnet relative to the Hall element. When the spatial positions of the two change, a voltage waveform with fixed characteristics is output. As shown in Figure 4 When subjected to counterclockwise twist, the output value of the sensor will decrease with the increase of the twist. When subjected to clockwise twist, the output value of the sensor will increase with the increase of the twist.

[0077] In one embodiment, the disclosure also provides a method for preparing the twist tactile sensor as shown in Figure 1 The method comprises the following steps:

[0078] S1, preparing the overall structure of the sensor based on 3D printing technology;

[0079] S2, embed the rectangular magnet into the structure, manually apply flexible resin for packaging, and cure again in the ultraviolet curing box; specifically, curing at 45°C for 2 min is required;

[0080] S3, paste the Hall element on the hard circuit board with AB glue;

[0081] S4, paste the sensor structure on the hard circuit board with quick-drying glue.

[0082] S5, print the flexible resin sensing layer by using the flexible 3D printing process, and cure in the ultraviolet curing box.

[0083] S6, apply the RTV coating on the flexible resin sensing layer, and cure at room temperature for 24 h.

[0084] The sensor of the embodiment has at least the following advantages and beneficial effects relative to the prior art:

[0085] (1) Small volume: the sensor has small size, light weight, and simple electrical structure.

[0086] (2) Low energy consumption: the energy required by a single planar Hall element is much smaller than that of other arrayed sensors based on sensing principles and three-dimensional Hall elements, and no external amplification circuit is required, and voltage output is directly performed.

[0087] (3) Modularization: different sensitivity tactile sensors can be prepared by selecting different magnets and Hall elements.

[0088] (4) Portability: these methods and technologies are platform-independent and can be adapted to various robot platforms.

[0089] (5) Productivity: the sensor construction is relatively fast, simple, and inexpensive, and is easy to implement in a large-scale robot skin system.

[0090] The above describes the basic principles of the application in combination with specific embodiments, but it should be pointed out that the advantages, advantages, effects, etc. mentioned in the application are only examples and not limitations, and these advantages, advantages, effects, etc. cannot be considered as the must-have of each embodiment of the application. In addition, the above specific details are only for the purpose of example and understanding, and are not limited to the application of the above specific details.

[0091] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the application to the forms disclosed herein. Although the above has discussed a plurality of example aspects and embodiments, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. A compression-torsion tactile sensor characterized by, It comprises, a sensor base body, the upper surface of which is provided with an upwardly protruding sensor base inner locking ring; a Hall element, which is nested in the sensor base body, a magnet skeleton, which comprises a cylinder provided below and a plate structure located at the top of the cylinder, the cylinder is provided with a groove inside, the periphery of the plate structure is provided with a fitting protrusion, and the groove inside the cylinder is connected with the sensor base inner locking ring to avoid interference from tangential force; a magnet, which is provided in the groove; a flexible resin sensing layer, which is provided with a positioning groove for matching the fitting protrusion to connect the flexible resin sensing layer with the magnet skeleton; a silicone elastomer, which is nested in the sensor base body and bonded between the flexible resin sensing layer and the sensor base body to compress or twist based on the external force or torque transmitted by the flexible resin sensing layer, so that the spatial position of the magnet skeleton changes and the magnet moves up and down and rotates, an RTV anti-skid layer, which is connected to the flexible resin sensing layer.

2. The compression-torsion tactile sensor of claim 1, wherein, The Hall element is a planar Hall element.

3. The compression-torsion tactile sensor of claim 1, wherein, The silicone elastomer is in a ring structure.

4. The compression-torsion tactile sensor of claim 1, wherein, The surface of the Hall element is provided with an anti-skid coating.

5. The compression-torsion tactile sensor of claim 1, wherein, The magnet is an axisymmetric magnet.

6. The compression-torsion tactile sensor of claim 1, wherein, The Hall element is used to convert the change of the magnetic flux density component of the three-dimensional magnetic field perpendicular to the plane into a voltage signal, and the Hall element is connected through a data acquisition card to transmit the voltage signal to a computer to obtain the size and direction of the pressure and torque.

7. The compression-torsion tactile sensor of claim 1, wherein, A first straight line passing through the center of the magnet and perpendicular to the upper surface of the magnet is parallel to a second straight line passing through the center of the Hall element and perpendicular to the upper surface of the Hall element, and the Hall element is a central symmetric structure.

8. The compression-torsion tactile sensor of claim 1, wherein, The magnet is a rectangular magnet.

9. The compression-torsion tactile sensor of claim 1, wherein, The RTV anti-skid layer, the flexible resin sensing layer, the magnet skeleton and the silicone elastomer share a common central axis.

10. A method of manufacturing a compression-shear haptic sensor as claimed in any one of claims 1-9, characterized in that, It comprises the following steps: Based on 3D printing technology, the sensor base body, the RTV anti-skid layer, the flexible resin sensing layer, the magnet skeleton and the silicone elastomer of the pressure and torque tactile sensor are prepared; The magnet is embedded in the magnet skeleton, coated with flexible resin for packaging, and cured again in a ultraviolet curing box, and the groove in the cylinder is connected with the sensor base inner locking ring to avoid interference from tangential force; The Hall element is pasted on the circuit board and nested in the sensor base body; The RTV anti-skid layer is scraped on the flexible resin sensing layer and cured at room temperature, and the positioning groove of the flexible resin sensing layer matches the fitting protrusion to connect the flexible resin sensing layer with the magnet skeleton, The silicone elastomer is nested in the sensor base body and bonded between the flexible resin sensing layer and the sensor base body to change the spatial position of the magnet skeleton based on the external force transmitted by the flexible resin sensing layer, so that the magnet moves up and down and rotates.

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