Magnetoelectric flexible tactile sensor

Abstract

The invention discloses a magnetoelectric flexible tactile sensor which comprises a magnetoelastic body, a supporting part, a flexible circuit board, a concave part and a magnetic field sensor, the concave part is located above the supporting part, the magnetoelastic body is aligned with the concave part, and the magnetic field sensor is located on the flexible circuit board and located between the supporting part and the flexible circuit board. The magnetoelastic body is used for generating corresponding magnetic field distribution according to external contact pressure, the magnetic field sensor is used for collecting magnetic field signals of the magnetoelastic body, and the contact part of the lower part of the magnetoelastic body and the concave part is of a pyramid array structure. According to the magnetoelectric flexible tactile sensor disclosed by the invention, the structure of the magnetoelastomer is pyramid-shaped, the sensitivity of the flexible tactile sensor is improved, and meanwhile, the magnetic field signal is processed through the pre-trained convolutional neural network, so that tactile information on the tactile sensor is directly obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of sensors, and in particular relates to a magnetoelectric flexible tactile sensor. Background Art

[0002] Flexible tactile sensors are also called "electronic skin". Compared with rigid sensors, they are stretchable and bendable and can adapt to various shapes of carriers. Due to these characteristics, there are currently a wide range of research directions for tactile sensors, including resistive, capacitive, piezoelectric, magnetoelectric and other sensing principles.

[0003] At present, the application of flexible tactile sensors is still relatively rare and remains in the laboratory research and development stage. The main reasons are as follows: the production cost of flexible tactile sensors is too high and difficult to commercialize; the production process of flexible tactile sensors is too complicated, and there is a lack of simple and large-scale flexible tactile sensor production processes; most tactile sensors cannot analyze and process external forces and give real-time responses to multimodal signals.

[0004] The touch outside the magnetoelectric flexible tactile sensor will change the position of the magnetic source and affect the magnetic field generated by the magnetic source. The position and size of the touch are judged by the magnetic field sensor and the signal processing unit. Compared with flexible tactile sensors of other sensing forms, the sensing part and the circuit part of the magnetoelectric flexible tactile sensor are separated, so it has the following advantages: the sensing part can be prepared and produced separately, and if elastic fatigue occurs after repeated pressure, the sensing part can be replaced at any time; the sensing structure can be changed by replacing the sensing part, so that elastomers with different pressure ranges and sensitivities can be designed to adapt to different sensing environments; the sensor is separated from the circuit, the preparation process is simple, and the cost is low; the pressure will not affect the circuit part through the sensing part, which can ensure the stability of the circuit.

[0005] However, the existing magnetoelectric flexible tactile sensors cannot provide a solution for the commercial mass production of tactile sensors. Accordingly, this field urgently needs to make further research and design to design a magnetoelectric flexible tactile sensor that is easy to commercialize, simplifies production, and is easy to replace, so as to better meet the integration and commercialization of humanoid robots or other fields. Summary of the invention

[0006] In view of the defects of the prior art and the need for improvement, the present invention provides a magnetoelectric flexible tactile sensor, comprising: a magnetic elastomer, a supporting portion, a flexible circuit board, a recessed portion and a magnetic field sensor, wherein the recessed portion is located above the supporting portion, the magnetic elastomer is aligned with the recessed portion, the magnetic field sensor is located on the flexible circuit board, between the supporting portion and the flexible circuit board, the magnetic elastomer is used to generate a corresponding magnetic field distribution according to an external contact pressure, and the magnetic field sensor is used to collect a magnetic field signal of the magnetic elastomer, wherein the lower portion of the magnetic elastomer in contact with the recessed portion is a pyramid array structure.

[0007] Furthermore, the magnetoelectric flexible tactile sensor also includes a signal processing unit, which includes a trained machine learning model for processing the magnetic field signal and generating tactile information.

[0008] Furthermore, the tactile information includes pressure distribution and size.

[0009] Furthermore, the magnetic field sensors are arranged in an array on the flexible printed circuit board.

[0010] Furthermore, the magnetic field sensors are arranged in 3*3, the size of the magnetic field sensor array is 2cm*2cm, and the inside of the magnetic field sensor array is divided into 4*4 pressure areas, wherein the size of each pressure area is 0.5cm*0.5cm.

[0011] Furthermore, the pyramid array has a height of 2 mm, a base size of 2 mm*2 mm, and a distance between each pyramid structure is 4 mm.

[0012] Furthermore, the magnetic field sensor is a three-dimensional Hall sensor.

[0013] Furthermore, the magnetic elastomer is a polydimethylsiloxane elastomer containing neodymium iron boron magnetic powder.

[0014] Furthermore, the magnetic field sensor uses an I2C bus to output the magnetic field signal.

[0015] Furthermore, when the magnetic elastic body is subjected to external contact pressure, it is embedded in the recessed body.

[0016] In general, in the magnetoelectric flexible tactile sensor disclosed in the present invention, the structure of the magnetic elastomer is pyramid-shaped, which improves the sensitivity of the flexible tactile sensor. At the same time, the magnetic field signal is processed by a pre-trained convolutional neural network to directly obtain the pressure position and size on the tactile sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic structural diagram of a magnetoelectric flexible tactile sensor provided by an embodiment of the present invention;

[0018] Figure 2 A magnetic field distribution diagram of the tactile sensor when the magnetoelectric flexible tactile sensor provided by an embodiment of the present invention is not subjected to pressure;

[0019] Figure 3 A magnetic field distribution diagram of the tactile sensor when the magnetoelectric flexible tactile sensor provided by an embodiment of the present invention is subjected to pressure;

[0020] Figure 4 A comparison chart of the pressure sensitivity of the magnetoelectric flexible tactile sensor provided by an embodiment of the present invention and elastic bodies with different structures; and

[0021] Figure 5 A diagram of the arrangement of magnetic field sensors and pressure positioning areas in a magnetoelectric flexible tactile sensor provided in an embodiment of the present invention.

[0022] Figure 6 A pressure output diagram of the magnetoelectric flexible tactile sensor provided in an embodiment of the present invention when different pressures are applied. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0024] In the present invention, the terms "first", "second", etc. (if any) in the present invention and the drawings are used to distinguish similar objects but not necessarily to describe a specific order or sequence.

[0025] Figure 1 The following is a schematic diagram of the structure of a magnetoelectric flexible tactile sensor provided by an embodiment of the present invention. Figure 1As shown, the magnetoelectric flexible tactile sensor includes: a magnetic elastomer 11, a support part 12, a flexible circuit board 13, a recessed part 14, a magnetic field sensor 15, and a signal processing unit 16. The magnetic elastomer 11 is a polydimethylsiloxane elastomer doped with neodymium iron boron magnetic powder, which belongs to a magnetic film structure and is used to generate a corresponding magnetic field distribution according to the external contact pressure. The support part 12 is a support component printed with polylactic acid 3D. The support part 12 serves as a carrier of the upper magnetic elastomer, and has a recessed structure 14 on its surface. The recessed structure 14 is used for the self-alignment scheme of the magnetic elastomer 11, which can ensure that the position of the magnetic elastomer 11 will not be horizontally offset. The flexible circuit board 13 is a flexible circuit board of a magnetic field sensor, and the flexible circuit board 13 is distributed with magnetic field sensors 15, such as a three-dimensional Hall sensor array of model MLX90393. The magnetic field sensor 15 is used to collect the magnetic field signal generated by the magnetic elastomer 11. The signal processing unit 16 includes a machine learning model for processing the magnetic field signal collected by the magnetic field sensor 15, and obtaining the pressure position and magnitude through the magnetic field signal. The signal processing unit 16 is located on the flexible circuit board 13 or is independent of the flexible circuit board 13. In the magnetoelectric flexible tactile sensor disclosed in the present invention, the circuit is separated from the sensor without generating relative horizontal movement. Furthermore, the lower part of the magnetic elastomer 11, that is, the part in contact with the support part 12, is designed as a pyramid array structure. The gaps between the pyramids allow the magnetic film to have space for deformation. At the same time, the pyramid's own structure of being wide at the top and narrow at the bottom makes it easier to deform when it is subjected to pressure, which can make the tactile sensor more sensitive and accurate in detecting touch or pressure changes at different parts, thereby obtaining tactile information, which includes pressure magnitude and pressure distribution information.

[0026] Figure 2 The magnetic field distribution diagram of the tactile sensor provided by the embodiment of the present invention when the magnetoelectric flexible tactile sensor is not subjected to pressure. Figure 2 As shown, the magnetoelectric flexible tactile sensor includes a magnetic elastic body 21, a support part 22, a flexible circuit board 23 and a magnetic field sensor 24, wherein the magnetic sensor 24 is an array composed of three-dimensional Hall sensors MLX90393. When the magnetic elastic body 21 does not apply pressure, the magnetic field excited by the magnetic elastic body 21 is as shown in FIG. Figure 2 As shown, the magnetic field distribution at the center is mainly a component in the vertical direction, and the magnetic field value is small, while the magnetic field distribution at the edge is mainly a component in the horizontal direction, and the magnetic field value is large.

[0027] Figure 3The magnetic field distribution diagram of the tactile sensor when the magnetoelectric flexible tactile sensor provided by the embodiment of the present invention is subjected to pressure. As shown in the figure, when pressure is applied to the concave part of the magnetic elastic body 21, the deformation energy generated by the magnetic elastic body 21 changes the magnetic field it excites, and the magnetic field sensor 24 located directly below the pressure will obtain different magnetic field change responses due to the position difference of different sensors in the horizontal direction, and the tactile information, that is, the pressure magnitude and pressure distribution, is calculated according to the magnetic field change.

[0028] Figure 4 A comparison chart of pressure sensitivities of the magnetoelectric flexible tactile sensor provided by an embodiment of the present invention and elastic bodies with different structures. Figure 4 Will combine Figure 1 Describe, such as Figure 4 The figure shows the pressure sensitivity test diagrams of four different structural elastomers, namely, bottomless structure, pyramid type, cylindrical type and pyramid type. Specifically, when the same pressure is applied to the surface of the magnetic elastomer 11, the deformations produced by different structures are different, and the magnetic field changes produced are also different. By comparing the curves, it can be obtained that the pyramid structure has the highest pressure sensitivity, and has higher detection accuracy and measurement range during pressure sensing. In addition, different parameters of the pyramid structure will also affect the measurement range and sensitivity of the tactile sensor. The larger the size of the pyramid structure, the higher its sensitivity will be, but the measurement range will become smaller; the larger the distance between the pyramid structures, the lower its sensitivity will be, but the measurement range will become larger. In one embodiment of the present invention, the height of the pyramid array is 2mm, the bottom size is 2mm*2mm, and the distance between each pyramid structure is 4mm.

[0029] Figure 5 A diagram of the sensor arrangement and pressure positioning area in the magnetoelectric flexible tactile sensor provided in an embodiment of the present invention. The magnetic field sensor 51 is a 3*3 array, and the distance between each sensor is 1 cm. The 3*3 magnetic field sensor array is divided into 4*4 pressure areas 52, and pressure is applied in each area each time pressure is applied. In one embodiment of the present invention, the magnetic field sensor array has a size of 2cm*2cm and is arranged in a 3*3 array. The distance between adjacent magnetic field sensors is 1 cm. Further, in order to better apply pressure, the 3*3 magnetic field sensor array is divided into 4*4 areas, each of which is 0.5cm*0.5cm. Each time pressure is applied, one or several continuous areas in the 4*4 area are selected to apply random pressure as the data for the test set and the training set. Furthermore, the magnetic field conversion signal captured by the magnetic field sensor is input into a pre-trained neural network model to obtain the pressure size and pressure distribution of 16 points in the 4*4 area, and obtain the pressure intensity of the tactile sensor at the 16 points. Specifically, Figure 5 Will combine Figure 1 Describe, such as Figure 5 As shown, the magnetic field sensors in the magnetoelectric flexible tactile sensor are arranged in a 3*3 array to measure the magnetic field changes generated by touch. Each sensor in the array is responsible for capturing the change signal of the local magnetic field, and the magnetic field change signal reflects the position and size of the touch pressure. The magnetic field sensor 51 transmits the collected magnetic field signal to the signal processing unit 16 through the I2C interface, and performs pre-processing such as denoising and normalization on the magnetic field signal, and then inputs it into the trained neural network model. Among them, the input layer of the network receives three-dimensional data from the magnetic field sensor array and extracts features through the hierarchical structure of the neural network.

[0030] Figure 6 The pressure output diagram of the magnetoelectric flexible tactile sensor provided by the embodiment of the present invention when different pressures are applied. Figure 6 It can be seen that the tactile sensor has a strong positioning function under single-point pressure and high recognition accuracy, and the maximum measurement error of the pressure size is 13.5%.

[0031] In one embodiment of the present invention, a convolutional neural network architecture is used to process the input magnetic field signal through the weight matrix obtained through training, and the location and size of the pressure source are accurately inferred. Specifically, based on the weight matrix obtained through training of the experimental data set, the convolutional neural network can learn the mapping relationship between magnetic field changes and pressure, and provide high-precision real-time prediction. The neural network not only improves the detection accuracy of the pressure position and size, but also reduces the array size of the magnetic field sensor, so that the pressure sensor can detect the pressure with a smaller number of sensors, reducing the circuit production cost.

[0032] The trained matrix can directly convert the input magnetic field signal into the position and magnitude of pressure through convolution operation and full connection. There is no need for further training in actual use. This matrix can be directly operated with the input magnetic field signal to obtain the actual pressure position and magnitude.

[0033] Through the magnetoelectric flexible tactile sensor disclosed by the present invention, the structure of the magnetic elastomer is pyramid-shaped, which improves the sensitivity of the flexible tactile sensor. At the same time, the magnetic field signal is processed by a pre-trained convolutional neural network to directly obtain the pressure position and size on the tactile sensor.

[0034] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A magnetoelectric flexible tactile sensor, characterized in that: include: A magnetic elastomer, a support portion, a flexible circuit board, a recessed portion, and a magnetic field sensor, wherein the recessed portion is located above the support portion, the magnetic elastomer is aligned with the recessed portion, the magnetic field sensor is located on the flexible circuit board, between the support portion and the flexible circuit board, the magnetic elastomer is used to generate a corresponding magnetic field distribution according to an external contact pressure, and the magnetic field sensor is used to collect a magnetic field signal of the magnetic elastomer, wherein the lower portion of the magnetic elastomer that contacts the recessed portion is a pyramid array structure.

2. The magnetoelectric flexible tactile sensor according to claim 1, characterized in that: It also includes a signal processing unit, which contains a trained machine learning model for processing the magnetic field signal and generating tactile information.

3. The magnetoelectric flexible tactile sensor according to claim 2, characterized in that: The tactile information includes pressure distribution and magnitude.

4. The magnetoelectric flexible tactile sensor according to claim 1, characterized in that: The magnetic field sensors are arranged in an array on the flexible circuit board.

5. The magnetoelectric flexible tactile sensor according to claim 4, characterized in that: The magnetic field sensors are arranged in 3*3 arrays, the size of the magnetic field sensor array is 2cm*2cm, and the inside of the magnetic field sensor array is divided into 4*4 pressure areas, wherein the size of each pressure area is 0.5cm*0.5cm.

6. The magnetoelectric flexible tactile sensor according to claim 1, characterized in that: The pyramid array has a height of 2 mm, a base size of 2 mm*2 mm, and a distance between each pyramid structure is 4 mm.

7. The magnetoelectric flexible tactile sensor according to claim 1, characterized in that: The magnetic field sensor is a three-dimensional Hall sensor.

8. The magnetoelectric flexible tactile sensor according to claim 1, characterized in that: The magnetic elastomer is a polydimethylsiloxane elastomer containing neodymium iron boron magnetic powder.

9. The magnetoelectric flexible tactile sensor according to claim 1, characterized in that: The magnetic field sensor outputs the magnetic field signal using an I2C bus.

10. The magnetoelectric flexible tactile sensor according to claim 1, characterized in that: When the magnetic elastic body is subjected to external contact pressure, it is embedded in the recessed body.

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