Three-dimensional array magnetic haptic sensor

Abstract

This invention relates to the field of tactile sensor technology, specifically a three-dimensional array magnetic tactile sensor. The purpose of this application is to address the problems of existing tactile sensors, such as low sensitivity and accuracy, hysteresis, and insufficient spatial resolution due to small material deformation. Furthermore, existing sensors suffer from range and sensitivity mismatch, severe multi-point cross-interference, and difficulty in decoupling three-dimensional force coupling. This application comprises a flexible load-bearing layer, a functional layer, and a signal acquisition layer stacked from top to bottom. Multiple sensing units in the functional layer are fixed to the lower surface of the flexible load-bearing layer. The functional layer and the signal acquisition layer are elastically connected, and the information transmission terminals of the multiple sensing units are respectively aligned with multiple Hall sensors on the signal acquisition layer. When the flexible load-bearing layer is subjected to an external load, the magnetic field strength between the information transmission terminals and the Hall sensors changes. The Hall sensors collect the change in magnetic induction intensity and upload it to a host computer.

Description

Technical Field

[0001] This application belongs to the field of tactile sensor technology. Background Technology

[0002] Tactile sensation is a crucial means for humanoid robots to perceive their external environment and acquire information at the end effector level. It plays a vital role in improving the robot's flexibility and ease of use, and its performance largely determines the overall performance of the robot. Humans are able to perform highly dexterous tasks such as threading a needle, picking up eggs, and tying shoelaces thanks to the high-density, multimodal tactile receptors distributed in their fingertips. These receptors can sense rich information such as pressure, vibration, shear force, and temperature in real time and feed this information back to the brain, forming an efficient "perception-control" closed loop. Therefore, for robots to achieve human-like operation, they need to obtain real-time force perception and feedback through tactile sensors. Equipping robot actuators with advanced tactile sensors is of great significance for improving the robot's fine manipulation capabilities, dexterity, and perception abilities.

[0003] Current tactile sensors, especially those based on the magnetoelectric principle, use rigid magnets embedded in flexible materials or soft magnetic materials. Since the flexible material is a hyperelastic material with small deformation, it suffers from problems such as low sensitivity and accuracy, hysteresis, and insufficient spatial resolution. At the same time, it also suffers from problems such as small range under high sensitivity, poor sensitivity when the range is large, severe cross-interference at multiple points, and difficulty in decoupling three-dimensional force coupling. Summary of the Invention

[0004] This application aims to address the problems of existing tactile sensors, such as low sensitivity and accuracy, hysteresis and insufficient spatial resolution due to small material deformation, as well as the mismatch between measurement range and sensitivity, severe multi-point cross-interference, and difficulty in decoupling three-dimensional force coupling. A three-dimensional array magnetic tactile sensor is provided.

[0005] This application provides a three-dimensional array magnetic tactile sensor, comprising: a flexible load-bearing layer, a functional layer, and a signal acquisition layer;

[0006] The functional layer includes multiple sensing units arranged in an array. All of the multiple sensing units are fixed on the lower surface of the flexible load-equalizing layer. The flexible load-equalizing layer can uniformly transfer external loads to the sensing units.

[0007] The lower surface of the functional layer is elastically connected to the upper surface of the signal acquisition layer. The upper surface of the signal acquisition layer is provided with multiple Hall sensors, and the information transmission ends of the multiple sensing units are respectively directly opposite the multiple Hall sensors.

[0008] When the flexible load-bearing layer is subjected to an external load, the magnetic field strength of the spatial magnetic field between the information transmission end of the sensing unit at the load location and the corresponding Hall sensor changes. The Hall sensor can collect the change in magnetic induction intensity and upload it to the host computer.

[0009] In one possible design, the three-dimensional array magnetic tactile sensor also includes a support layer, the lower surface of which is rigidly connected to the upper surface of the signal acquisition layer, leaving a space between them. The support layer can protect the Hall sensor on the signal acquisition layer from direct external loads.

[0010] The lower surface of the functional layer is elastically connected to the upper surface of the support layer, and the support layer is provided with a plurality of through holes that can be directly aligned with the information transmission ends of the Hall sensor and the sensing unit.

[0011] In one possible design, the material of the support layer is a photosensitive resin.

[0012] In one possible design, the sensing unit includes a support plate and a magnet. The lower surface of the support plate is connected to the upper surface of the support layer via an elastic post. The magnet is fixed at the geometric center of the lower surface of the support plate and serves as the information transmission end of the sensing unit.

[0013] In one possible design, the support plate is a regular hexagon, and the array is arranged in the densest possible arrangement of regular hexagonal planes;

[0014] The number of elastic pillars is 3, and the 3 elastic pillars are located at the three vertices of an equilateral triangle. Each elastic pillar is directly opposite the midpoint of the corresponding side of a regular hexagon. The magnet is located at the geometric center of the equilateral triangle.

[0015] In one possible design, the elastic column is a rubber column, and the magnet is a cylindrical rubidium magnet.

[0016] In one possible design, the length of the elastic column is 2.5 mm, the length of the magnet is 1 mm, the thickness of the bearing layer is 1 mm, and the gap between the magnet and the corresponding Hall sensor is 2 mm.

[0017] In one possible design, the signal acquisition layer is a PCB board, the plurality of Hall sensors are mounted on the PCB board, and are electrically connected to the Hall sensors via a multiplexer on the PCB board.

[0018] In one possible design, the multiplexer communicates with the Hall sensor via I2C, and the Hall sensor communicates with the host computer via I2C.

[0019] In one possible design, the multiplexer is a TCA9548A 8-channel I2C switch chip.

[0020] The beneficial effects of this application are:

[0021] This application solves the problems of crosstalk, low positioning accuracy, and insufficient sensitivity caused by high structural rigidity in traditional tactile sensors during multi-point pressure detection through a new structural design. It achieves three-dimensional force sensing with high spatial resolution, low crosstalk, and high stability. The sensor has a range of over 15N, a minimum trigger force of 0.3N, a sensitivity of 0.01N, a repeatability of less than 1%FS, and a measurement accuracy of less than 15%FS. The synergistic effect of each layer shortens the system response time to less than 10ms, the response frequency to 100Hz, the positioning error to less than 1mm, and the overall thickness to less than 5mm, meeting the requirements of miniaturized embedded applications.

[0022] Meanwhile, the unique layout of the sensing units enables modular design and sensor scalability, allowing for the expansion of the number of sensing units to meet the special needs of sensing areas of different sizes and shapes.

[0023] Finally, this application has a simple structure, is easy to process and assemble, and uses readily available and low-cost materials. Attached Figure Description

[0024] Figure 1 This is an exploded view of the structure of the three-dimensional array magnetic tactile sensor in the embodiment;

[0025] Figure 2 This is a front view of the three-dimensional array magnetic tactile sensor in the embodiment;

[0026] Figure 3 This is a side view of the three-dimensional array magnetic tactile sensor in the embodiment;

[0027] Figure 4 This is a schematic diagram of the three-dimensional array magnetic tactile sensor in the embodiment;

[0028] Figure 5 This is a schematic diagram of the layout of the elastic pillars and magnets in a single sensing unit in the embodiment;

[0029] Figure 6 This is a three-dimensional schematic diagram showing the layout of the elastic pillars and magnets in a single sensing unit in the embodiment;

[0030] Figure 7 This is a schematic diagram of the PCB board circuit for the signal acquisition layer in the embodiment.

[0031] The markings in the diagram are as follows: 1. Flexible load-bearing layer; 2. Load-bearing plate; 3. Rubber column; 4. Magnet; 5. Load-bearing layer; 6. PCB board; 7. Hall sensor. Detailed Implementation

[0032] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0033] Specific Implementation Method 1: The three-dimensional array magnetic tactile sensor described in this implementation method includes: a flexible load-bearing layer, a functional layer, and a signal acquisition layer;

[0034] The functional layer includes multiple sensing units arranged in an array. All of the multiple sensing units are fixed on the lower surface of the flexible load-equalizing layer. The flexible load-equalizing layer can uniformly transfer external loads to the sensing units.

[0035] The lower surface of the functional layer is elastically connected to the upper surface of the signal acquisition layer. The upper surface of the signal acquisition layer is provided with multiple Hall sensors, and the information transmission ends of the multiple sensing units are respectively directly opposite the multiple Hall sensors.

[0036] When the flexible load-bearing layer is subjected to an external load, the magnetic field strength of the spatial magnetic field between the information transmission end of the sensing unit at the load location and the corresponding Hall sensor changes. The Hall sensor can collect the change in magnetic induction intensity and upload it to the host computer.

[0037] In one embodiment, the three-dimensional array magnetic tactile sensor further includes a support layer, the lower surface of which is rigidly connected to the upper surface of the signal acquisition layer, leaving a space between them. The support layer can protect the Hall sensor on the signal acquisition layer from direct external loads.

[0038] The lower surface of the functional layer is elastically connected to the upper surface of the support layer, and the support layer is provided with a plurality of through holes that can be directly aligned with the information transmission ends of the Hall sensor and the sensing unit.

[0039] In one embodiment, the material of the carrier layer is a photosensitive resin.

[0040] In one embodiment, the sensing unit includes a support plate and a magnet. The lower surface of the support plate is connected to the upper surface of the support layer via an elastic column. The magnet is fixed at the geometric center of the lower surface of the support plate and serves as the information transmission end of the sensing unit.

[0041] In one embodiment, the support plate is a regular hexagon, and the array is arranged in the densest possible arrangement of regular hexagonal planes;

[0042] The number of elastic pillars is 3, and the 3 elastic pillars are located at the three vertices of an equilateral triangle. Each elastic pillar is directly opposite the midpoint of the corresponding side of a regular hexagon. The magnet is located at the geometric center of the equilateral triangle.

[0043] In one embodiment, the elastic column is a rubber column, and the magnet is a cylindrical rubidium magnet.

[0044] In one embodiment, the length of the elastic column is 2.5 mm, the length of the magnet is 1 mm, the thickness of the bearing layer is 1 mm, and the gap between the magnet and the corresponding Hall sensor is 2 mm.

[0045] In one embodiment, the signal acquisition layer is a PCB board, and the plurality of Hall sensors are disposed on the PCB board and electrically connected to the multiplexer and Hall sensors on the PCB board.

[0046] In one embodiment, the multiplexer communicates with the Hall sensor via I2C, and the Hall sensor communicates with the host computer via I2C.

[0047] In one embodiment, the multiplexer is a TCA9548A 8-channel I2C switch chip.

[0048] To further illustrate the implementation scheme of this application, Figure 1 A three-dimensional array magnetic tactile sensor is provided, and each structure is described in detail below:

[0049] A three-dimensional array magnetic tactile sensor consists of four layers: a flexible load-bearing layer 1, a functional layer, a load-bearing layer 5, and a signal acquisition layer, which are stacked and bonded together from top to bottom.

[0050] The top layer of the sensor is a flexible load-bearing layer 1. This layer serves as the flexible surface of the entire sensor in contact with the outside world, uniformly transferring the external load to the sensing unit array in the next layer. The flexible load-bearing layer 1 is made of a flexible and stretchable material. In this embodiment, Sylgard 184 type PDMS is used. The PDMS and curing agent are mixed in a ratio of 10:1. This ratio meets the sensor's requirements for the tensile strength and elongation at break of the flexible load-bearing layer material.

[0051] The second layer is the functional layer, the core structure of the three-dimensional array magnetic tactile sensor. It consists of seven identical sensing units arranged in an array, with the array arrangement being a densely packed hexagonal plane. In practical applications, the number of sensing units in the three-dimensional array tactile sensor is not limited to seven; it can be expanded or reduced to any number, and if necessary, the number of units can be increased to cover the required surface to the maximum extent. Each sensing unit consists of a regular hexagonal support plate 2, a cylindrical neodymium magnet, and three rubber pillars 3, with their positional relationships shown in the attached figure. Figure 5 and Figure 6 As shown, the three rubber pillars 3 are arranged in an equilateral triangle, with the center of the triangle coinciding with the center of the support plate 2. The vertices of the triangles are on the center lines of the sides of the regular hexagon, and the cylindrical neodymium magnet is located at the center of the equilateral triangle. The upper side of the support plate 2 is fixed to the flexible support layer 1 by adhesive bonding. The three rubber pillars 3 are connected to the support plate 2 on top and the support layer 5 on the bottom, and are also fixed by adhesive bonding, supporting the support plate 2 on the support layer 5. The cylindrical magnet 4 is embedded on one side below the support plate 2.

[0052] The third layer is the carrier layer 5, made of photosensitive resin. Through holes are provided on the carrier layer 5 corresponding to the positions of the magnets 4 to prevent interference when the magnets 4 are displaced; there are also shallow grooves arranged in an equilateral triangle and with the same diameter as the rubber pillars 3, facilitating adhesive application and positioning when bonding the rubber pillars 3, reducing positional errors during installation. The function of the carrier layer 5 is to bear external forces, preventing external loads from acting directly on the PCB board 6 and protecting the Hall sensor 7 from damage. When the sensing units of the functional layer are expanded to multiple units, requiring coverage of a larger area, and the entire tactile sensor is used as flexible electronic skin, the carrier layer 5 can be fixed on the circuit board in the same shape and size as the carrier plate 2, forming an array corresponding one-to-one with the carrier plate 2. Combined with the signal acquisition layer, an FPCB is used to achieve the flexibility of the entire sensor. Thus, the sensor can act as electronic skin to cover curved surfaces.

[0053] The fourth layer is the signal acquisition layer, and the principle of the signal acquisition circuit is as follows: Figure 7As shown, the signal acquisition circuit includes a PCB board 6, on which are mounted Hall sensors 7 corresponding one-to-one with the magnets in the functional layer, a multiplexer for multi-channel signal acquisition, and power and data interfaces. The multiplexer communicates with the Hall sensors 7 via I2C, polling the magnetic field data detected by the Hall sensors 7 and outputting the acquired magnetic field data to the host computer via I2C. The multiplexer uses a TCA9548A 8-channel I2C switch chip, controlling the selection of the seven Hall sensors 7 through two I2C buses, effectively reducing I2C address conflicts. The PCB board 6 does not integrate a microcontroller unit; all raw magnetic field data is uploaded to the host computer in real time via the I2C bus. The host computer performs data decoupling, three-dimensional force calculation, and visualization. This distributed processing architecture reduces the complexity and power consumption of the sensor body, while facilitating subsequent algorithm upgrades and model optimization.

[0054] The working principle of the three-dimensional array magnetic tactile sensor described in this embodiment is as follows:

[0055] After the host computer sends the start acquisition command, the multiplexer sequentially selects each Hall sensor 7 according to a preset timing sequence. Each Hall sensor 7 completes one triaxial magnetic field data acquisition (approximately 1ms), and the seven sensing units poll (acquisition cycle approximately 10ms, corresponding to a sampling frequency of 100Hz). The acquired raw data includes the magnetic induction intensity components (Bx, By, Bz) at each Hall sensor 7, which are transmitted to the host computer via the I2C bus in 16-bit signed integer format. The host computer pre-stores a three-dimensional force calibration model, which was obtained through extensive experimental data training. This model establishes a nonlinear mapping relationship between the magnet displacement deflection state and the change in the output magnetic field of the Hall sensor, as well as the mechanical relationship between the magnet state and the external three-dimensional forces.

[0056] In actual measurement, when the sensor is subjected to an external load, the flexible load-sharing layer 1 undergoes elastic deformation. The load is transferred to the support plate 2 of one or more sensing units through the flexible load-sharing layer 1. After the support plate 2 is subjected to the load, the elastic column 3 supporting the support plate 2 will deform, thus causing the support plate 2 to displace and deflect. When the external force acts on the gaps between the array of sensing units in the form of point contact, the sensor can still effectively measure and sense due to the presence of the flexible load-sharing layer 1. Correspondingly, the magnet 4 fixed on the lower side of the support plate 2 will also displace and deflect. At this time, the magnetic field strength of the spatial magnetic field will change, and the corresponding Hall sensor 7 can detect the change in the magnetic induction intensity component at its location. Based on the real-time collected magnetic field data, the host computer solves for the optimal three-dimensional force components (Fx, Fy, Fz) and the coordinates of the action position (x, y) through an iterative optimization algorithm, realizing the synchronous sensing of three-dimensional force and contact position.

[0057] To meet the displacement requirements of magnet 4, in this embodiment, the length of rubber column 3 is greater than the length of magnet 4, and sufficient to maintain a certain gap between magnet 4 and Hall sensor 7. In this embodiment, the length of rubber column 3 is 2.5 mm, the length of magnet 4 is 1 mm, the thickness of bearing layer 5 is 1 mm, and the gap between magnet 4 and Hall sensor 7 is 2 mm. Furthermore, in this embodiment, the size of the gap between magnet 4 and Hall sensor 7 can be controlled by selecting different combinations of rubber column 3 and magnet 4 lengths, as well as the thickness of bearing layer 5, thereby controlling the measurement range of the sensor. By selecting the elastic modulus and aspect ratio of rubber column 3, the sensitivity of the sensor can be controlled.

[0058] While specific embodiments of this application have been described herein with reference to them, it should be understood that these embodiments are merely examples of the principles and applications of this application. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed without departing from the spirit and scope of this application as defined by the appended claims. It should be understood that different dependent claims and features described herein can be combined in ways different from those described in the original claims. It is also understood that features described in conjunction with individual embodiments can be used in other described embodiments.

Claims

1. A three-dimensional array magnetic tactile sensor, characterized in that, include: Flexible load-sharing layer, functional layer and signal acquisition layer; The functional layer includes multiple sensing units arranged in an array. All of the multiple sensing units are fixed on the lower surface of the flexible load-equalizing layer. The flexible load-equalizing layer can uniformly transfer external loads to the sensing units. The lower surface of the functional layer is elastically connected to the upper surface of the signal acquisition layer. The upper surface of the signal acquisition layer is provided with multiple Hall sensors, and the information transmission ends of the multiple sensing units are respectively directly opposite the multiple Hall sensors. When the flexible load-bearing layer is subjected to an external load, the magnetic field strength of the spatial magnetic field between the information transmission end of the sensing unit at the load location and the corresponding Hall sensor changes. The Hall sensor can collect the change in magnetic induction intensity and upload it to the host computer.

2. The three-dimensional array magnetic tactile sensor according to claim 1, characterized in that, It also includes a support layer, the lower surface of which is rigidly connected to the upper surface of the signal acquisition layer, leaving a space between them; The lower surface of the functional layer is elastically connected to the upper surface of the support layer, and the support layer is provided with a plurality of through holes that can be directly aligned with the information transmission ends of the Hall sensor and the sensing unit.

3. The three-dimensional array magnetic tactile sensor according to claim 2, characterized in that, The material of the support layer is photosensitive resin.

4. The three-dimensional array magnetic tactile sensor according to claim 2 or 3, characterized in that, The sensing unit includes a support plate and a magnet. The lower surface of the support plate is connected to the upper surface of the support layer through an elastic column. The magnet is fixed at the geometric center of the lower surface of the support plate and serves as the information transmission end of the sensing unit.

5. The three-dimensional array magnetic tactile sensor according to claim 4, characterized in that, The support plate is a regular hexagon, and the array is arranged in the densest plane arrangement of regular hexagons; The number of elastic pillars is 3, and the 3 elastic pillars are located at the three vertices of an equilateral triangle. Each elastic pillar is directly opposite the midpoint of the corresponding side of a regular hexagon. The magnet is located at the geometric center of the equilateral triangle.

6. The three-dimensional array magnetic tactile sensor according to claim 4, characterized in that, The elastic column is a rubber column, and the magnet is a cylindrical rubidium magnet.

7. The three-dimensional array magnetic tactile sensor according to claim 4, characterized in that, The elastic column has a length of 2.5 mm, the magnet has a length of 1 mm, the bearing layer has a thickness of 1 mm, and the gap between the magnet and the corresponding Hall sensor is 2 mm.

8. The three-dimensional array magnetic tactile sensor according to claim 1 or 2, characterized in that, The signal acquisition layer is a PCB board, and the multiple Hall sensors are mounted on the PCB board and electrically connected to the multiplexer and Hall sensors on the PCB board.

9. The three-dimensional array magnetic tactile sensor according to claim 8, characterized in that, The multiplexer communicates with the Hall sensor via I2C, and the Hall sensor communicates with the host computer via I2C.

10. The three-dimensional array magnetic tactile sensor according to claim 8, characterized in that, The multiplexer is a TCA9548A 8-channel I2C switch chip.

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