Pressure-torsion tactile sensor and preparation method thereof

Abstract

According to the pressure-torsion tactile sensor and the preparation method thereof, in the sensor, the upper surface of a sensor base body is provided with a sensor base inner locking ring protruding upwards; the Hall element is nested in the sensor base body, the magnet framework comprises a cylinder arranged on the lower portion and a plate-shaped structure located at the top of the cylinder, a groove is formed in the cylinder, embedded protrusions are arranged on the periphery of the plate-shaped structure, and the cylinder is connected with an inner locking ring of the sensor base in a locking mode so as to be prevented from being interfered by tangential force; the magnet is arranged in the groove; the flexible resin sensing layer is provided with positioning grooves used for being matched with the embedded protrusions so as to be connected with the flexible resin sensing layer and the magnet framework. The silicone 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 be compressed or twisted based on external force or torque transmitted by the flexible resin sensing layer, so that the spatial position of the magnet framework is changed, and the magnet moves and rotates up and down; the RTV anti-skid layer is connected to the flexible resin sensing layer.

Description

Technical Field

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

[0002] Multi-dimensional force tactile sensors play an important role in the process of robots perceiving the world, flexibly manipulating, performing complex tasks, and interacting with people. They are an indispensable part of robots moving towards intelligence and anthropomorphism. At present, tactile sensors are mainly divided into resistive, capacitive, piezoelectric, photosensitive, etc. according to their principles. The above-mentioned sensors are often only sensitive to pressure measurement, and it is difficult to measure the torsion occurring at the sensor interface.

[0003] The information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Summary of the invention

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

[0005] The purpose of the present invention is achieved through the following technical solutions.

[0006] A compression-torsion tactile sensor, comprising: The sensor base body has an upper surface provided with an upwardly protruding sensor base inner locking ring; The Hall element is embedded in the sensor base. The magnet frame includes a cylinder disposed at the bottom and a plate-like structure located at the top of the cylinder, wherein a groove is disposed in the cylinder, and an engaging protrusion is disposed at the periphery of the plate-like structure, and the cylinder is locked and connected to the locking ring inside the sensor base to avoid interference from tangential forces; a magnet disposed in the groove; A flexible resin sensing layer, which is provided with a positioning groove for matching the engaging protrusion to connect the flexible resin sensing layer and the magnet skeleton; The silicone rubber elastomer is embedded in the sensor base body and bonded between the flexible resin sensing layer and the sensor base body to compress or twist the external force or torque transmitted by the flexible resin sensing layer, so that the spatial position of the magnet frame changes and the magnet moves up and down and rotates. The RTV anti-slip layer is connected to the flexible resin sensing layer.

[0007] In the compression-torsion tactile sensor, the Hall element is a planar Hall element.

[0008] In the compression-torsion tactile sensor, the silicone rubber elastomer is a ring-shaped structure.

[0009] In the compression-torsion tactile sensor, the surface of the Hall element is provided with an anti-slip coating.

[0010] In the compression-torsion tactile sensor, the magnet is an axisymmetric magnet.

[0011] In the compression-torsion tactile sensor, 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. The Hall element is connected through a data acquisition card to transmit its voltage signal to a computer to obtain the magnitude and direction of pressure and torque.

[0012] In the compression-torsion 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 centrosymmetric structure.

[0013] In the compression-torsion tactile sensor, the magnet is a rectangular magnet.

[0014] In the compression-torsion tactile sensor, the RTV anti-slip layer, the flexible resin sensing layer, the magnetic skeleton and the silicone rubber elastomer share a central axis.

[0015] The method for preparing the compression-torsion tactile sensor comprises the following steps: The sensor base body, RTV anti-slip layer, flexible resin sensing layer, magnetic skeleton and silicone rubber elastomer of the compression-torsion tactile sensor are prepared based on 3D printing technology; The magnet is embedded in the magnet frame, and a flexible resin is applied for encapsulation, and then cured again in a UV curing box, and the cylinder is locked and connected to the locking ring inside the sensor base to avoid interference from tangential forces; The Hall element is pasted on the circuit board and nested in the sensor base body; The RTV anti-slip layer is scraped onto the flexible resin sensing layer and cured at room temperature. The positioning groove of the flexible resin sensing layer is matched with the engaging protrusion to connect the flexible resin sensing layer and the magnet frame. The silicone rubber elastomer is embedded 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.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention can convert the external pressure and torque into voltage signals, 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 achieve 0.2 and ultra-high torque and angle resolution of 0.1°, and more than 150 The measuring range can be improved by designing the size of the annular elastomer, for example, reducing the cross-sectional area of ​​the ring or increasing the length of the beam, so that the overall elastic modulus becomes smaller and it is easier to produce displacement under external force. The production is simple, the production cycle is short and the cost is extremely low. At the same time, the sensor is highly designable. The production of different flexible matrix structures can be achieved through material processing, which greatly shortens the design and verification cycle. The range of the sensor can be further controlled by controlling the curing price. Compared with other types of compression-torsion sensors, magnetic sensors have natural advantages in three-dimensional force measurement, and can imitate the skin of human hands to measure dynamic and static forces.

[0017] The above description is only an overview of the technical solution of the present invention. In order to make the technical means of the present invention clearer and to achieve the extent that those skilled in the art can implement it according to the contents of the specification, and in order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are exemplified below. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] By reading the detailed description of the preferred specific embodiments below, various other advantages and benefits of the present invention will become clear to those of ordinary skill in the art. The drawings in the specification are only for the purpose of illustrating the preferred embodiments and are not considered to be limitations of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative work. Moreover, the same reference numerals are used to represent the same components throughout the drawings.

[0019] In the attached picture: Figure 1 It is a schematic diagram of the structure of the present invention; Figure 2 It is a schematic diagram of the explosion structure of the present invention; Figure 3It is a schematic diagram of the pressure signal change of the present invention; Figure 4 It is a schematic diagram of the torque signal change of the present invention.

[0020] The present invention is further explained below in conjunction with the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0021] The specific embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the specific embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to enable the scope of the present invention to be fully communicated to those skilled in the art.

[0022] It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction. As mentioned throughout the specification and claims, "including" or "comprising" is an open term, so it should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the present invention, but the description is based on the general principles of the specification and is not intended to limit the scope of the present invention. The scope of protection of the present invention shall be determined by the attached claims.

[0023] To facilitate understanding of the embodiments of the present invention, several specific embodiments will be further explained below with reference to the accompanying drawings, and each of the accompanying drawings does not constitute a limitation on the embodiments of the present invention.

[0024] For a better understanding, Figures 1 to 4 As shown, a compression-torsion tactile sensor comprises: The sensor base body 10 has an upper surface provided with an upwardly protruding sensor base inner locking ring 9; The Hall element 7 is embedded in the sensor base body 10. The magnet skeleton 5 includes a cylinder disposed at the bottom and a plate-like structure located at the top of the cylinder, wherein a groove is disposed in the cylinder, and an engaging protrusion 4 is disposed at the periphery of the plate-like structure, and the cylinder is locked and connected to the locking ring 9 in the sensor base to avoid interference from tangential forces; a magnet 6, which is disposed in the groove; A flexible resin sensing layer 3, which is provided with a positioning groove 2 for matching the embedding protrusion 4, so as to connect the flexible resin sensing layer 3 and the magnet skeleton 5; The silicone rubber elastomer 8 is embedded 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 the external force or torque transmitted by the flexible resin sensing layer 3, so that the spatial position of the magnet skeleton 5 changes, thereby causing the magnet to move up and down and rotate. The RTV anti-slip layer 1 is connected to the flexible resin sensing layer 3 .

[0025] In a preferred embodiment of the compression-torsion tactile sensor, the Hall element 7 is a planar Hall element 7 .

[0026] In the preferred embodiment of the compression-torsion tactile sensor, the silicone rubber elastic body 8 is a ring-shaped structure.

[0027] In the preferred embodiment of the compression-torsion tactile sensor, the surface of the Hall element 7 is provided with an anti-slip coating.

[0028] In a preferred embodiment of the compression-torsion tactile sensor, the magnet 6 is an axisymmetric magnet.

[0029] In a preferred embodiment of the compression-torsion tactile sensor, the Hall element 7 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 7 is connected through a data acquisition card to transmit its voltage signal to a computer to obtain the magnitude and direction of the pressure and torque.

[0030] In a preferred embodiment of the compression-torsion 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 7 and perpendicular to the upper surface of the Hall element 7, and the Hall element 7 is a centrally symmetrical structure.

[0031] In a preferred embodiment of the compression-torsion tactile sensor, the magnet 6 is a rectangular magnet.

[0032] In a preferred embodiment of the compression-torsion tactile sensor, the RTV anti-slip layer 1, the flexible resin sensing layer 3, the magnetic skeleton 5 and the silicone rubber elastomer 8 share a common central axis.

[0033] The method for preparing the compression-torsion tactile sensor comprises the following steps: A sensor base body 10, an RTV anti-slip layer 1, a flexible resin sensing layer 3, a magnetic skeleton 5 and a silicone rubber elastomer 8 of a compression-torsion tactile sensor are prepared based on 3D printing technology; The magnet is embedded in the magnet frame 5, coated with flexible resin for encapsulation, and cured again in a UV curing box, and the cylinder is locked and connected to the locking ring 9 inside the sensor base to avoid interference from tangential forces; The Hall element 7 is pasted on the circuit board and embedded in the sensor base body 10; The RTV anti-slip layer 1 is scraped onto the flexible resin sensing layer 3 and cured at room temperature. The positioning groove 2 of the flexible resin sensing layer 3 is matched with the embedded protrusion 4 to connect the flexible resin sensing layer 3 with the magnetic skeleton 5. The silicone rubber 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.

[0034] In one embodiment, the RTV anti-slip layer 1 is connected to the flexible resin sensing layer 3, and the flexible resin sensing layer 3 has a positioning groove inside, which is convenient for connection with the magnet frame 5. The outer side of the magnet frame 5 has a fitting protrusion 4 to facilitate connection and positioning with the flexible resin sensing layer 3. The magnet frame 5 has a groove inside for storing magnets.

[0035] In one embodiment, the silicone rubber elastomer 8 is nested directly above the sensor base; the magnet skeleton 5 and the sensor base are nested with each other, allowing the sensor to only sense changes in pressure and torque, and the flexible matrix structure is deformed under the action of external force, causing the relative spatial position of the magnet and the Hall element 7 to change; the Hall element 7 is used to sense the component of the three-dimensional magnetic flux density perpendicular to the Hall plane, and the pressure and torque measurement is achieved based on the electrical signal generated by the Hall element 7.

[0036] In one embodiment, the center of the magnet and the center of the Hall element 7 are offset from each other in space, and the silicone rubber elastomer 8 is deformed under the action of an external force, so that the relative spatial position of the magnet and the Hall element 7 changes.

[0037] In one embodiment, the compression-torsion tactile sensor can convert the external force / torque it receives 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.

[0038] In one embodiment, the Hall element 7 is used to sense the component of the three-dimensional magnetic flux density perpendicular to the Hall plane, and the multi-dimensional force measurement is achieved based on the Hall voltage generated by the Hall element 7.

[0039] Preferably, the magnet is a rectangular magnet. It is used to generate a three-dimensional anisotropic magnetic field, and the magnetic field distribution characteristics are similar to the shape of a rectangular magnet. The magnetic flux density decreases quickly along the short side of the magnet and slowly along the long side of the magnet, which provides a guarantee for the anisotropy of the output voltage of the Hall element 7 moving along the x-axis and along the y-axis. Compared with a circular magnet with central symmetry, the Hall element 7 moves in all directions, and the signal voltage changes in the same way, making it difficult to distinguish the direction of movement.

[0040] In one embodiment, the Hall element 7 is used to convert the change of the magnetic flux density component of the three-dimensional magnetic field perpendicular to the plane into an electrical signal output. The voltage signal is transmitted to the computer through a data acquisition card to obtain the magnitude and direction of the force / torque.

[0041] In one embodiment, the RTV anti-skid layer 1 can increase the friction coefficient of the surface of the object to prevent torsional slippage when in contact with the object, thereby causing inaccurate torque measurement. The flexible resin sensing layer 3 can ensure good contact with the outside world and better transmit the contact force to the middle silicone rubber elastomer 8. At the same time, the flexible resin layer has a structure that imitates human fingerprints, which greatly increases the area with the RTV anti-skid layer, thereby ensuring that the coating does not fall off. An annularly distributed positioning groove 2 is provided below the flexible resin layer to facilitate connection with the interlocking protrusion 4 of the magnet skeleton. A groove is designed below the magnet skeleton 5 to facilitate the embedding of the magnet. The magnetic sensitive element used is a planar Hall element 7, which can convert the change of the component of the spatial 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 unidirectional magnetic flux component perpendicular to the surface.

[0042] The middle annular silicone rubber elastomer can convert external force or torque into the up and down movement and rotation of the magnet's spatial position, thereby achieving displacement in the positive pressure direction and change in the torsion angle of the torque along the pressure direction. The locking ring 9 in the sensor base is locked with the magnet skeleton 5 to ensure that it is not disturbed by the tangential force. The silicone rubber elastomer 8 and the Hall element 7 in the middle of the sensor can be nested in the sensor base body 10 of the sensor.

[0043] The compression-torsion tactile sensor is calibrated using a Cartesian coordinate system and can be subjected to torques and pressures of different magnitudes in different directions. When the flexible resin sensing layer 3 is subjected to an external force / torque, the pressure can be transmitted to the entire annular silicone rubber elastomer 8, and the annular silicone rubber elastomer 8 generates corresponding compression and torsion according to the external force / torque it is subjected to.

[0044] According to the difference in force / torque, the flexible resin sensing layer 3 produces different displacement changes, and at the same time drives the magnetic skeleton 5 to produce spatial displacement. When the spatial position of the magnetic skeleton 5 changes, the spatial position of the rectangular magnet 6 also changes accordingly.

[0045] The output voltage of the planar Hall element 7 changes with the change of the detected magnetic field. In the initial state, the rectangular magnet 6 and the planar Hall element 7 are relatively offset in space by a certain distance. The direction and magnitude of the force / torque can be determined based on the shape characteristics and magnitude of the voltage change.

[0046] The "force-magnetism-electricity" conversion process is now completed. The single voltage signal is collected into the computer through an oscilloscope or a data acquisition card, and the magnitude and direction of the force / torque on the flexible resin sensing layer 3 are solved according to the corresponding algorithm.

[0047] The specific acquisition 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 for transmission, and then convert the digital quantity into analog quantity for display in the computer. The judgment is made according to the signal characteristics corresponding to different loading methods. The signal characteristics are as follows. When a tangential load is applied along the positive direction of 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. Figure 3 As shown in the figure, it is the waveform of the load applied in the positive direction along the Z axis. When the pressure is close to 50N, the sensor outputs a voltage change of nearly 300mV. When the torsion 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. Figure 4 As shown in the figure, when the sensor is twisted counterclockwise, the output value of the sensor will decrease as the twist increases. When the sensor is twisted clockwise, the output value of the sensor will increase as the twist increases.

[0048] In one embodiment, the present disclosure also provides a method for preparing Figure 1 The method of the torsion tactile sensor shown comprises the following steps: S1. Prepare the overall structure of the sensor based on 3D printing technology; S2. Embed the rectangular magnet into the structure, manually apply flexible resin for encapsulation, and cure it again in a UV curing box; specifically, it needs to be cured at 45°C for 2 minutes; S3, stick the Hall element on the hard circuit board with AB glue; S4. Glue the sensor structure onto the hard circuit board using quick-drying glue.

[0049] S5. Print the flexible resin sensing layer using a flexible 3D printing process and cure it in a UV curing box.

[0050] S6. Scrape the RTV coating onto the flexible resin sensing layer and cure it at room temperature for 24 hours.

[0051] Compared with the prior art, the sensor of this embodiment has at least the following advantages and beneficial effects: (1) Small size: The sensor is small in size, light in weight, and has a simple electrical structure.

[0052] (2) Low energy consumption: The energy required by a single planar Hall element is much smaller than that of other sensing principle array sensors and three-dimensional Hall elements. It does not require an external amplification circuit and directly outputs voltage.

[0053] (3) Modularity: Tactile sensors with different sensitivities can be prepared by selecting different magnets and Hall elements.

[0054] (4) Portability: These methods and techniques are platform-independent and can be adapted to various robotic platforms.

[0055] (5) Producibility: The sensor construction is relatively fast, simple, and cheap, and it is easy to realize large-scale robotic skin systems.

[0056] The basic principles of the present application are described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, effects, etc. mentioned in the present application are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present application. In addition, the specific details disclosed above are only for the purpose of illustration and ease of understanding, not for limitation, and the above details do not limit the present application to being implemented by adopting the above specific details.

[0057] 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 present application to the forms disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. A compression-torsion tactile sensor, characterized in that: These include, The sensor base body has an upper surface provided with an upwardly protruding sensor base inner locking ring; The Hall element is embedded in the sensor base. The magnet frame includes a cylinder disposed at the bottom and a plate-like structure located at the top of the cylinder, wherein a groove is disposed in the cylinder, and an engaging protrusion is disposed at the periphery of the plate-like structure, and the cylinder is locked and connected to the locking ring inside the sensor base to avoid interference from tangential forces; a magnet disposed in the groove; A flexible resin sensing layer, which is provided with a positioning groove for matching the engaging protrusion to connect the flexible resin sensing layer with the magnet skeleton; The silicone rubber elastomer is embedded in the sensor base body and bonded between the flexible resin sensing layer and the sensor base body to compress or twist the external force or torque transmitted by the flexible resin sensing layer, so that the spatial position of the magnet frame changes and the magnet moves up and down and rotates. The RTV anti-slip layer is connected to the flexible resin sensing layer.

2. The compression-torsion tactile sensor according to claim 1, wherein: Preferably, the Hall element is a planar Hall element.

3. The compression-torsion tactile sensor according to claim 1, wherein: The silicone rubber elastomer is a ring-shaped structure.

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

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

6. The compression-torsion tactile sensor according to 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. The Hall element is connected through a data acquisition card to transmit its voltage signal to a computer to obtain the size and direction of pressure and torque.

7. The compression-torsion tactile sensor according to 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 centrally symmetrical structure.

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

9. The compression-torsion tactile sensor according to claim 1, wherein: The RTV anti-slip layer, the flexible resin sensing layer, the magnet skeleton and the silicone rubber elastomer share a central axis.

10. A method for preparing a compression-torsion tactile sensor according to any one of claims 1 to 9, characterized in that: It includes the following steps: The sensor base body, RTV anti-slip layer, flexible resin sensing layer, magnetic skeleton and silicone rubber elastomer of the compression-torsion tactile sensor are prepared based on 3D printing technology; The magnet is embedded in the magnet frame, and a flexible resin is applied for encapsulation, and then cured again in a UV curing box, and the cylinder is locked and connected to the locking ring inside the sensor base to avoid interference from tangential forces; The Hall element is pasted on the circuit board and nested in the sensor base body; The RTV anti-slip layer is scraped onto the flexible resin sensing layer and cured at room temperature. The positioning groove of the flexible resin sensing layer is matched with the engaging protrusion to connect the flexible resin sensing layer and the magnet frame. The silicone rubber elastomer is embedded 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.

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