Optical fiber tactile sensor and method of manufacture

Abstract

The application discloses a kind of optical fiber tactile sensor and preparation method, including one or more tactile units, tactile unit is connected with camera by optical fiber, the camera is connected with data processing unit, the data processing unit is used to process and calculate image data, obtain tactile information;The tactile unit includes shell, is provided with light collecting layer in shell, is attached with light guide cover layer on the upper portion of light collecting layer, frame is fixed with light guide cover layer;Frame is installed on the upper portion of shell;Multi-color light source is set on the side of light guide cover layer, the lower surface of light guide cover layer is convex array structure;Optical fiber passes through shell and is connected with light collecting layer.The optical fiber tactile sensor of the application is low in manufacturing cost, and strong in anti-interference ability.

Description

Technical Field

[0001] This invention relates to an optical fiber tactile sensor, belonging to the field of intelligent sensing technology. Background Technology

[0002] Fiber optic tactile sensors are a sensor technology used to measure touch and strain. They utilize the properties of optical fibers to detect changes in the external environment. The basic principle of fiber optic tactile sensors is based on the influence of external strain on light signals propagating in the fiber. This strain causes changes in the light signal within the fiber, such as phase changes or light intensity changes. These changes can be measured and analyzed to determine external tactile or strain information. Fiber optic tactile sensors can employ different operating principles, including interferometric, scattering, and intensity-based types. Interferometric fiber optic sensors are based on changes in optical path difference caused by external strain, scattering sensors are based on changes in scattered light signals, and intensity-based sensors focus on changes in light intensity. Existing fiber optic tactile sensors use grating fibers, which place stringent requirements on optical signal demodulation equipment, resulting in high costs, and the manufacturing process of the grating fibers themselves is complex. Currently, at least the following problems have been identified regarding fiber optic tactile sensor technology:

[0003] 1) The grating in the grating fiber is a high-precision structure, and its fabrication process is complex and the equipment is expensive;

[0004] 2) The grating signal demodulator of grating fiber is a high-precision electronic device and is expensive;

[0005] 3) Light intensity type tactile sensors are suitable for single-point tactile measurement, but it is difficult to realize tactile arrays.

[0006] CN115574998A discloses a fiber optic spot tactile sensor with a reflective probe structure. The force applied to the probe contact causes deformation of the reflector, resulting in a change in the output spot. The spot pattern is used as the sensing signal. Since the spot change is mainly caused by the reflector deformation, changes in the bending state of the output fiber have little impact on the output spot, thus exhibiting anti-bending interference capability. However, this scheme is designed for single-point tactile detection and is difficult to perform large-scale tactile measurements. CN116067542A discloses a method for identifying the magnitude and direction of a three-dimensional force tactile sensor using a mechanically anisotropic cylindrical fiber optic grating. Under the action of a normal force, the cylinder is compressed along the Z-axis, causing both FBGs to compress simultaneously, and the center wavelength to drift towards a shorter wavelength direction. The angle of the tangential force is identified by the sign and proportional relationship of the center wavelength drift of the two FBGs, and the magnitude of the tangential force is identified by the amplitude of the drift. However, this scheme uses grating fibers as the sensing unit, resulting in complex grating fabrication processes and high grating signal demodulation costs. Summary of the Invention

[0007] The technical problem to be solved by the present invention is that the production cost of existing fiber optic tactile sensors is relatively high due to the complexity of gratings and fabrication processes, as well as the high cost of grating signal demodulator equipment.

[0008] The technical problem that this invention aims to solve further is that existing fiber optic tactile sensors are difficult to use for large-area tactile measurement.

[0009] To solve the above-mentioned technical problems, the present invention provides an optical fiber tactile sensor, including one or more tactile units. The tactile units are connected to a camera 6 via an optical fiber 5. The camera 6 is connected to a data processing unit 7, which is used to process and calculate image data to obtain tactile information.

[0010] The tactile unit includes a housing 8, a light-collecting layer 4 is disposed inside the housing 8, a light-guiding cover layer 1 is attached to the upper part of the light-collecting layer 4, and a frame 3 fixes the light-guiding cover layer; the frame 3 is installed on the upper part of the housing 8.

[0011] The multi-color light source 2 is disposed on one side of the light guide cover layer 1, and the lower surface of the light guide cover layer 1 is a raised array structure;

[0012] Optical fiber 5 passes through the outer shell 8 and is connected to the light-collecting layer 4.

[0013] In the aforementioned fiber optic tactile sensor, the multi-color light source 2 is fixed inside the light source pre-reserved hole of the frame 3; the multi-color light sources 2 are evenly arranged with a spacing of 5 mm between each color light source.

[0014] In the aforementioned fiber optic tactile sensor, the protrusions on the lower surface of the light-guiding cover layer 1 are hemispherical, pyramidal, conical, or frustum-shaped.

[0015] The aforementioned fiber optic tactile sensor, when the protrusion is hemispherical, has a diameter of 1.8 mm, a spacing of 2 mm between hemispheres, and an array size of 10 per row, for a total of 10 rows.

[0016] In the aforementioned fiber optic tactile sensor, the light-guiding cover layer 1 is made of dimethylsiloxane PDMS material with a thickness of 2-3 mm; the light-collecting layer 4 is made of polydimethylsiloxane PDMS; and the outer shell 8 is made of polylactic acid PLA.

[0017] The aforementioned fiber optic tactile sensor comprises four tactile units arranged in a 2x2 array; or

[0018] The tactile unit consists of 7 units, each of which is hexagonal, with a central tactile unit surrounded by 6 other tactile units.

[0019] The aforementioned fiber optic tactile sensor includes an image data processing module in its data processing unit 7. This module processes and calculates image data using a convolutional neural network. The structure of the convolutional neural network is as follows:

[0020] C1: An input layer (101) that receives RGB image input of size 224×224×3 for receiving image data to be classified;

[0021] C2: The first convolutional layer (102) is used to perform convolution calculations on the output image of C1 and convert the image matrix dimension to 224×224×32;

[0022] C3: A max pooling layer (103) is used to reduce the data dimension of the C2 output image to 112×112×32;

[0023] C4: The second convolutional layer (104) performs a convolution operation on the output of the previous layer, increasing the image matrix dimension to 112×112×64;

[0024] C5: The second max pooling layer (105) reduces the data dimension to 56×56×64;

[0025] C6: The third convolutional layer (106) increases the dimension of the image data matrix to 56×56×128;

[0026] C7: The third max pooling layer (107) reduces the data dimension of the previous layer to 28×28×128;

[0027] C8: Data flattening layer (108), used to flatten the previous layer's 28×28×128 image data matrix into a vector with 2048 elements;

[0028] C9: A fully connected layer (109) with ReLU activation function, used to process the flattened data from the previous layer;

[0029] C10: The final fully connected layer (110) has a softmax activation function for classifying different categories of the data from the previous layer; the softmax activation function outputs a probability distribution of the predicted category to indicate the location and magnitude of the force, with the output label having the highest probability reflecting that the image comes from a specific test location and the magnitude of the force.

[0030] A method for fabricating a fiber optic tactile sensor includes the following steps:

[0031] S1: Design a mold for the top light guide cover layer of the fiber optic tactile sensor; the mold includes upper and lower parts, and the lower part of the mold includes a recess that matches the raised array structure;

[0032] S2: The upper and lower molds of the top light guide cover layer of the fiber optic tactile sensor are manufactured using polylactic acid (PLA) material and an extrusion 3D printer.

[0033] S3: Assemble the upper and lower mold parts together and use silicone adhesive for temporary sealing to prevent polydimethylsiloxane (PDMS) leakage;

[0034] S4: Mix the silicone and crosslinking agent of the PDMS kit at a ratio of 10:1, pour the mixture into the cover layer mold, and then cure it in a hot oven at 70-80 degrees Celsius for 0.8-1 hours;

[0035] S5: Demold PDMS from PLA mold to form light guide cover layer, and then cut the light guide cover layer into a set shape and size. The cut light guide cover layer includes an extra set size margin edge for adhesion to the frame 3 supporting the light guide cover layer.

[0036] S6: Design and manufacture the tactile sensor housing 8, and then insert an optical fiber 5 into the bottom of the housing 8;

[0037] S7: Inject polydimethylsiloxane (PDMS) into the interior of the outer shell 8 and cure it in an oven at 70-80 degrees Celsius for 0.8-1 hour to prepare the light-collecting layer 4;

[0038] S8: Design and use PLA material to manufacture frame 3 for fixing light guide cover layer 1. A light source bracket is set on frame 3 for placing multi-color light source 2.

[0039] S9: Assemble the light guide cover layer 1, the outer shell 8 and the frame 3 together, so that the light guide cover layer, the light collecting layer and the optical fiber are assembled together to form the tactile unit of the optical fiber tactile sensor.

[0040] S10: Connect the optical fiber of the haptic unit to the camera 6;

[0041] S11: Connect the camera 6 to the data image processing system 7 to form a fiber optic tactile sensor.

[0042] In the aforementioned method for fabricating a fiber optic tactile sensor, in step S8, mounting holes for LED light sources are pre-drilled on the light source bracket, and the number of mounting holes is the same as the number of basic colors of the multi-color light source.

[0043] The aforementioned method for fabricating a fiber optic tactile sensor further includes the following step between steps S9 and S10:

[0044] Prepare four tactile units according to steps S1-S9, and assemble them in a 2*2 array; or

[0045] Prepare 7 tactile units according to steps S1-S9, with 6 tactile units surrounding a central tactile unit.

[0046] The beneficial effects achieved by this invention are as follows: This invention provides a fiber optic tactile sensor whose sensing structure simulates the complex structure between the epidermis and dermis of the skin. In terms of sensing principle, it utilizes the image information formed at the far end of a multi-color light field after propagation and dispersion in a multimode fiber. Tactile information is obtained by analyzing and calculating this image information. The sensor includes a light guide cover layer, a multi-color light source, a light-collecting layer, a shell, a multimode fiber, a camera, and a data processing system. The multi-color light source emits light into the light guide cover layer, forming a structured light field within it. Biomimetic protrusions are fabricated on the lower surface of the light guide cover layer, contacting the light-collecting layer. When tactile force or temperature changes are applied to the upper surface of the light guide cover layer, the contact between the lower surface of the light guide cover layer and the upper surface of the light-collecting layer changes, causing a change in the structured light. This changed light field is collected by the light-collecting layer, enters the near end of the fiber, and after propagation and dispersion, reaches the far end of the fiber. The camera collects the color image at the far end of the fiber, and the image data is analyzed and processed by the data processing system to obtain the tactile information on the cover layer.

[0047] The present invention discloses a fiber optic tactile sensor, which designs a convex array structure as the overlay sensing structure, uses a multi-color light field as the carrier of tactile information, and uses machine learning methods to process image data at the far end of the fiber optic cable. Compared with other piezoresistive, capacitive, and grating fiber optic tactile sensors, it has a low manufacturing cost and overcomes the shortcomings of traditional grating fiber optic tactile sensors, such as complex and expensive grating signal demodulation systems.

[0048] The fiber optic tactile sensor of the present invention can form a tactile sensing array by multiple tactile units, overcoming the disadvantages of traditional piezoresistive and capacitive sensors, such as numerous leads, easy failure, and high cost.

[0049] Meanwhile, the combination and arrangement of tactile units can realize large-area tactile measurement, reducing the difficulty of realizing large-area tactile measurement, and has reference value for other occasions such as deformation detection. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the fiber optic tactile sensor assembly in Embodiment 1 of the present invention;

[0051] Figure 2 This is a schematic diagram of the convolutional neural network structure of the fiber optic tactile sensor image processing system in Embodiment 1 of the present invention;

[0052] Figure 3 This is a schematic diagram of the internal structure and light field of the light guide cover layer in Embodiment 1 of the present invention, which uses 3-color LEDs as a multi-color light source.

[0053] Figure 4This is a schematic diagram of a 2*2 tactile array composed of 4 tactile units in Embodiment 2 of the present invention;

[0054] Figure 5 This is a schematic diagram of a large-area tactile array composed of seven hexagonal tactile units in Embodiment 3 of the present invention.

[0055] Reference numerals: 1. Light guide cover layer, 2. Multi-color light source, 3. Frame, 4. Light collecting layer, 5. Optical fiber, 6. Camera, 7. Data processing unit, 8. Housing. Detailed Implementation

[0056] The specific embodiments of the present invention are described below with reference to the accompanying drawings.

[0057] Example 1

[0058] This embodiment provides a fiber optic tactile sensor, including a tactile unit. The tactile unit is connected to a camera 6 via an optical fiber 5. The camera 6 is connected to a data processing unit 7, which processes and calculates image data to obtain tactile information.

[0059] The tactile unit includes a housing 8, a light-collecting layer 4 is disposed inside the housing 8, a light-guiding cover layer 1 is attached to the upper part of the light-collecting layer 4, and a frame 3 fixes the light-guiding cover layer; the frame 3 is installed on the upper part of the housing 8.

[0060] The multi-color light source 2 is set on one side of the light guide cover layer 1; the multi-color light source 2 is fixed in the light source reserved hole of the frame 3; the multi-color light sources 2 are evenly arranged with a spacing of 5 mm between each color light source;

[0061] The lower surface of the light guide cover layer 1 has a raised array structure;

[0062] The protrusions on the lower surface of the light guide cover layer 1 can be hemispherical, pyramidal, conical, or frustum, etc. When the protrusion is hemispherical, the diameter of the hemispherical is 1.8 mm and the spacing between the hemispheres is 2 mm. If the array size is 10 per row and there are 10 rows in total, that is, 100 protrusions.

[0063] The light guide cover layer 1 is stacked together with the light collection layer, and the light guide cover layer 1 is fixed to the frame 3 by PDMS;

[0064] The light guide cover layer 1 is made of dimethylsiloxane PDMS material with a thickness of about 2-3 mm;

[0065] The light-collecting layer 4 is made of polydimethylsiloxane (PDMS).

[0066] The outer shell 8 is made of polylactic acid (PLA).

[0067] Optical fiber 5 passes through the outer shell 8 and is connected to the light-collecting layer 4.

[0068] The working principle of the fiber optic tactile sensor of the present invention is as follows: the lower surface of the light guide cover layer 1 is a raised array structure. The raised array of the light guide cover layer is used to realize the modulation of light to sense external tactile information, including force, temperature, etc. The raised array structure is attached to the light collecting layer. The light emitted by the multi-color light source 2 forms structured light in the light guide cover layer 1. The structured light is collected by the light collecting layer 4 and enters the optical fiber 5 to propagate and disperse. A camera 6 is connected at the far end of the optical fiber 5 to collect the color image at the far end of the optical fiber 5. The image data is sent to the data processing system 7. After the image data is processed, the tactile information is calculated.

[0069] In data processing unit 7, an image data processing module is installed to process and calculate image data. This image data processing module uses a convolutional neural network to process the image data, such as... Figure 2 As shown, the structure of the convolutional neural network is as follows:

[0070] C1: An input layer (101) that receives RGB image input of size 224×224×3 for receiving image data to be classified;

[0071] C2: The first convolutional layer (102) is used to perform convolution calculations on the output image of C1 and convert the image matrix dimension to 224×224×32;

[0072] C3: A max pooling layer (103) is used to reduce the data dimension of the C2 output image to 112×112×32;

[0073] C4: The second convolutional layer (104) performs a convolution operation on the output of the previous layer, increasing the image matrix dimension to 112×112×64;

[0074] C5: The second max pooling layer (105) reduces the data dimension to 56×56×64;

[0075] C6: The third convolutional layer (106) increases the dimension of the image data matrix to 56×56×128;

[0076] C7: The third max pooling layer (107) reduces the data dimension of the previous layer to 28×28×128;

[0077] C8: Data flattening layer (108), used to flatten the previous layer's 28×28×128 image data matrix into a vector with 2048 elements;

[0078] C9: A fully connected layer (109) with ReLU activation function, used to process the flattened data from the previous layer;

[0079] C10: The final fully connected layer (110) has a softmax activation function for classifying different categories of the data from the previous layer; the softmax activation function outputs a probability distribution of the predicted category to indicate the location and magnitude of the force, with the output label having the highest probability reflecting that the image comes from a specific test location and the magnitude of the force.

[0080] The present invention discloses a method for fabricating an optical fiber tactile sensor, comprising the following steps:

[0081] S1: Design a mold for the top light guide cover layer of the fiber optic tactile sensor; the mold includes upper and lower parts, the lower mold includes a recess that matches the protruding array structure, and the cavity between the upper and lower molds is the cavity for manufacturing the light guide cover layer 1, the cavity volume is 24 mm * 24 mm * 3.5 mm;

[0082] S2: The upper and lower molds of the top light guide cover layer of the fiber optic tactile sensor are manufactured using polylactic acid (PLA) material and an extrusion 3D printer.

[0083] S3: Assemble the upper and lower mold parts together and temporarily seal them with silicone adhesive to prevent polydimethylsiloxane (PDMS) leakage; the silicone is conventional AB type silicone, which is cured at 60 degrees Celsius in a hot air box for 2 hours.

[0084] S4: Mix the silicone and crosslinking agent of the polydimethylsiloxane kit at a ratio of 10:1, pour the mixture into the cover layer mold, and then cure it in a hot oven at 70-80 degrees Celsius for 0.8-1 hours;

[0085] S5: Demold polydimethylsiloxane PDMS from PLA mold to form a light guide cover layer, and then cut the light guide cover layer into a set shape and size, such as a square with a side length of 22 mm × 22 mm. The cut light guide cover layer includes an extra set size margin edge for adhesion to the frame 3 supporting the light guide cover layer.

[0086] The light guide cover layer has a working area of ​​20 mm * 20 mm, with a margin edge width of 2 mm, and is bonded to the frame 3 using PDMS.

[0087] S6: Design and manufacture the tactile sensor housing 8, and then insert a section of optical fiber 5 into the bottom of the housing 8. The length of the optical fiber depends on the actual distance between the camera and the tactile sensor.

[0088] The outer shell 8 is printed using PLA material. The outer shell 8 has dimensions of 22 mm * 22 mm and an inner cavity height of 15 mm. The length of the optical fiber depends on the distance between the camera and sensor installation positions in the specific embodiment.

[0089] S7: Inject polydimethylsiloxane (PDMS) into the interior of the outer shell 8 and cure it in an oven at 70-80 degrees Celsius for 0.8-1 hour to prepare the light-collecting layer 4;

[0090] S8: A frame 3 is designed and manufactured using PLA material to fix the light guide cover layer. A light source bracket is set on the frame 3 to hold the multi-color light source 2.

[0091] In step S8, mounting holes for the LED light source are pre-drilled on the light source bracket; the number of mounting holes is the same as the number of basic colors of the multi-color light source, such as... Figure 3 As shown, if the LED light source has 3 colors, then the number of mounting holes is 3;

[0092] S9: Assemble the light guide cover layer 1, the outer shell 8 and the frame 3 together, so that the light guide cover layer, the light collecting layer and the optical fiber are assembled together to form the tactile unit of the optical fiber tactile sensor.

[0093] S10: Connect the optical fiber of the tactile unit in step S9 to the camera 6;

[0094] S11: Connect the camera 6 to the data image processing system 7 to form a fiber optic tactile sensor.

[0095] Example 2

[0096] Figure 4 As shown, this embodiment provides a fiber optic tactile sensor, including multiple tactile units. Each tactile unit is connected to a camera 6 via an optical fiber 5. The camera 6 is connected to a data processing unit 7, which processes and calculates image data to obtain tactile information.

[0097] The tactile unit includes a housing 8, a light-collecting layer 4 is disposed inside the housing 8, a light-guiding cover layer 1 is attached to the upper part of the light-collecting layer 4, and a frame 3 fixes the light-guiding cover layer; the frame 3 is installed on the upper part of the housing 8.

[0098] A multi-color light source 2 is disposed on one side of the light guide cover layer 1;

[0099] The lower surface of the light guide cover layer 1 has a raised array structure;

[0100] Optical fiber 5 passes through the outer shell 8 and is connected to the light-collecting layer 4.

[0101] The tactile unit consists of four units arranged in a 2x2 array; the optical fiber 5 of each tactile unit is connected to the camera 6, and the camera 6 is connected to the image data processing system 7.

[0102] This embodiment of a method for fabricating a fiber optic tactile sensor includes the following steps:

[0103] S1: Design a mold for the top light guide cover layer of the fiber optic tactile sensor; the mold includes upper and lower parts, the lower mold includes a recess that matches the protruding array structure, and the cavity between the upper and lower molds is the cavity for manufacturing the light guide cover layer 1, the cavity volume is 24 mm * 24 mm * 3.5 mm;

[0104] S2: The upper and lower molds of the top light guide cover layer of the fiber optic tactile sensor are manufactured using polylactic acid (PLA) material and an extrusion 3D printer.

[0105] S3: Assemble the upper and lower mold parts together and use silicone adhesive for temporary sealing to prevent polydimethylsiloxane (PDMS) leakage;

[0106] S4: Mix the silicone and crosslinking agent of the polydimethylsiloxane kit at a ratio of 10:1, pour the mixture into the cover layer mold, and then cure it in a hot oven at 70-80 degrees Celsius for 0.8-1 hours;

[0107] S5: Demold polydimethylsiloxane PDMS from PLA mold to form a light guide cover layer, and then cut the light guide cover layer into a set shape and size, such as a square with a side length of 22 mm × 22 mm. The cut light guide cover layer includes an extra set size margin edge for adhesion to the frame 3 supporting the light guide cover layer.

[0108] S6: Design and manufacture the tactile sensor housing 8 using PLA material, and then insert a section of optical fiber 5 into the bottom of the housing 8. The length of the optical fiber depends on the actual distance between the camera and the tactile sensor.

[0109] S7: Inject polydimethylsiloxane (PDMS) into the interior of the outer shell 8 and cure it in an oven at 70-80 degrees Celsius for 0.8-1 hour to prepare the light-collecting layer 4;

[0110] S8: A frame 3 is designed and manufactured using PLA material to fix the light guide cover layer. A light source bracket is set on the frame 3 to hold the multi-color light source 2.

[0111] S9: Assemble the light guide cover layer 1, the outer shell 8 and the frame 3 together, so that the light guide cover layer, the light collecting layer and the optical fiber are assembled together to form the tactile unit of the optical fiber tactile sensor.

[0112] S10: Prepare four tactile units according to steps S1-S9, and assemble them in a 2*2 array;

[0113] S11: Connect the four optical fibers of the four haptic units in S10 to the camera 6;

[0114] S12: Connect the camera 6 to the data image processing system 7 to form a fiber optic tactile sensor with a 2*2 tactile sensing array.

[0115] Example 3

[0116] Figure 5 As shown, this embodiment provides a fiber optic tactile sensor, including multiple tactile units. Each tactile unit is connected to a camera 6 via an optical fiber 5. The camera 6 is connected to a data processing unit 7, which processes and calculates image data to obtain tactile information.

[0117] The tactile unit includes a housing 8, a light-collecting layer 4 is disposed inside the housing 8, a light-guiding cover layer 1 is attached to the upper part of the light-collecting layer 4, and a frame 3 fixes the light-guiding cover layer; the frame 3 is installed on the upper part of the housing 8.

[0118] A multi-color light source 2 is disposed on one side of the light guide cover layer 1;

[0119] The lower surface of the light guide cover layer 1 has a raised array structure;

[0120] Optical fiber 5 passes through the outer shell 8 and is connected to the light-collecting layer 4.

[0121] The tactile unit consists of 7 units, each of which is hexagonal. A central tactile unit surrounds the other 6 tactile units. The optical fiber 5 of each tactile unit is connected to the camera 6, and the camera 6 is connected to the image data processing system 7.

[0122] This embodiment of a method for fabricating a fiber optic tactile sensor includes the following steps:

[0123] S1: Design a mold for the top light guide cover layer of the fiber optic tactile sensor; the mold includes upper and lower parts, the lower mold includes a recess that matches the protruding array structure, and the cavity between the upper and lower molds is the cavity for manufacturing the light guide cover layer 1, the cavity volume is 24 mm * 24 mm * 3.5 mm;

[0124] S2: The upper and lower molds of the top light guide cover layer of the fiber optic tactile sensor are manufactured using polylactic acid (PLA) material and an extrusion 3D printer.

[0125] S3: Assemble the upper and lower mold parts together and use silicone adhesive for temporary sealing to prevent polydimethylsiloxane (PDMS) leakage;

[0126] S4: Mix the silicone and crosslinking agent of the polydimethylsiloxane kit at a ratio of 10:1, pour the mixture into the cover layer mold, and then cure it in a hot oven at 70-80 degrees Celsius for 0.8-1 hours;

[0127] S5: Demold polydimethylsiloxane PDMS from PLA mold to form a light guide cover layer, and then cut the light guide cover layer into a set shape and size, such as a square with a side length of 22 mm × 22 mm. The cut light guide cover layer includes an extra set size margin edge for adhesion to the frame 3 supporting the light guide cover layer.

[0128] S6: Design and manufacture the tactile sensor housing 8 using PLA material, and then insert a section of optical fiber 5 into the bottom of the housing 8. The length of the optical fiber depends on the actual distance between the camera and the tactile sensor.

[0129] S7: Inject polydimethylsiloxane (PDMS) into the interior of the outer shell 8 and cure it in an oven at 70-80 degrees Celsius for 0.8-1 hour to prepare the light-collecting layer 4;

[0130] S8: A frame 3 is designed and manufactured using PLA material to fix the light guide cover layer. A light source bracket is set on the frame 3 to hold the multi-color light source 2.

[0131] S9: Assemble the light guide cover layer 1, the outer shell 8 and the frame 3 together, so that the light guide cover layer, the light collecting layer and the optical fiber are assembled together to form the tactile unit of the optical fiber tactile sensor.

[0132] S10: Prepare 7 tactile units according to steps S1-S9, with 6 tactile units surrounding a central tactile unit;

[0133] S11: Connect the 7 optical fibers of the 7 haptic units in S10 to the camera 6;

[0134] S12: Connect the camera 6 to the data image processing system 7 to form a fiber optic tactile sensor.

[0135] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A fiber optic tactile sensor, comprising one or more tactile units, characterized in that, The tactile unit is connected to the camera (6) via an optical fiber (5), and the camera (6) is connected to the data processing unit (7). The data processing unit (7) is used to process and calculate the image data to obtain tactile information. The tactile unit includes a housing (8), a light-collecting layer (4) is provided inside the housing (8), a light-guiding cover layer (1) is attached to the upper part of the light-collecting layer (4), and a frame (3) fixes the light-guiding cover layer; the frame (3) is installed on the upper part of the housing (8); A multi-color light source (2) is set on one side of the light guide cover layer (1), and the lower surface of the light guide cover layer (1) is a raised array structure; The optical fiber (5) passes through the outer shell (8) and is connected to the light-collecting layer (4).

2. The fiber optic tactile sensor according to claim 1, characterized in that, The multi-color light source (2) is fixed on the inner wall of the light source reserved hole of the frame (3); the multi-color light source (2) has each color light source arranged evenly, and the distance between each color light source is 5 mm.

3. The fiber optic tactile sensor according to claim 1, characterized in that, The protrusions on the lower surface of the light guide cover layer (1) are hemispherical, pyramidal, conical, or frustum.

4. The fiber optic tactile sensor according to claim 3, characterized in that, When the protrusion is hemispherical, the diameter of the hemisphere is 1.8 mm, the spacing between the hemispheres is 2 mm, and the array size is 10 per row, for a total of 10 rows.

5. The fiber optic tactile sensor according to claim 1, characterized in that, The light guide cover layer (1) is made of PDMS material with a thickness of 2-3 mm; the light collecting layer (4) is made of PDMS material; and the outer shell (8) is made of PLA material.

6. The fiber optic tactile sensor according to claim 1, characterized in that, The tactile units consist of four units arranged in a 2x2 array; or The tactile unit consists of 7 units, each of which is hexagonal, with a central tactile unit surrounded by 6 other tactile units.

7. The fiber optic tactile sensor according to claim 1, characterized in that, In the data processing unit (7), an image data processing module is run to process and calculate image data. The image data processing module uses a convolutional neural network to process the image data. The structure of the convolutional neural network is as follows: C1: An input layer (101) that receives RGB image input of size 224×224×3, used to receive image data to be classified; C2: The first convolutional layer (102) is used to perform convolution calculations on the output image of C1 and convert the image matrix dimension to 224×224×32; C3: A max pooling layer (103) is used to reduce the data dimension of the C2 output image to 112×112×32; C4: The second convolutional layer (104) performs a convolution operation on the output of the previous layer, increasing the image matrix dimension to 112×112×64; C5: The second max pooling layer (105) reduces the data dimension to 56×56×64; C6: The third convolutional layer (106) increases the dimension of the image data matrix to 56×56×128; C7: The third max pooling layer (107) reduces the data dimension of the previous layer to 28×28×128; C8: Data flattening layer (108), used to flatten the previous layer's 28×28×128 image data matrix into a vector with 2048 elements; C9: A fully connected layer (109) with ReLU activation function, used to process the data flattened by the previous layer; C10: The final fully connected layer (110) has a softmax activation function for classifying different categories of the data from the previous layer; the softmax activation function outputs a probability distribution of the predicted category to indicate the location and magnitude of the force, and the output label with the highest probability reflects that the image comes from a specific test location and the magnitude of the force.

8. A method for fabricating a fiber optic tactile sensor, characterized in that, Includes the following steps: S1: Design a mold for the top light guide cover layer of the fiber optic tactile sensor; the mold includes upper and lower parts, and the lower part of the mold includes a recess that matches the raised array structure; S2: Using PLA material, the upper and lower molds of the top light guide cover layer of the fiber optic tactile sensor are manufactured using an extrusion 3D printer; S3: Assemble the upper and lower mold parts together and temporarily seal them with silicone adhesive to prevent PDMS leakage; S4: Mix the silicone and crosslinking agent of the PDMS kit at a ratio of 10:1, pour the mixture into the cover layer mold, and then cure it in an oven at 70-80 degrees Celsius for 0.8-1 hour; S5: Demold PDMS from PLA mold to form light guide cover layer, and then cut the light guide cover layer into a set shape and size. The cut light guide cover layer includes an extra set size margin edge for adhesion to the frame (3) supporting the light guide cover layer. S6: Design and manufacture the tactile sensor housing (8), and then insert a section of optical fiber (5) into the bottom of the housing (8); S7: Inject PDMS into the interior of the outer shell (8) and cure it in an oven at 70-80 degrees Celsius for 0.8-1 hours to prepare a light-collecting layer (4); S8: Design and use PLA material to manufacture a frame (3) for fixing the light guide cover layer (1), and set a light source bracket on the frame (3) for placing multi-color light sources (2). S9: Assemble the light guide cover layer (1), the outer shell (8) and the frame (3) together, so that the light guide cover layer, the light collection layer and the optical fiber are assembled together to form the tactile unit of the optical fiber tactile sensor; S10: Connect the optical fiber of the haptic unit to the camera (6). S11: Connect the camera (6) to the data processing unit (7) to form a fiber optic tactile sensor.

9. The method for fabricating a fiber optic tactile sensor according to claim 8, characterized in that, In step S8, mounting holes for LED light sources are reserved on the light source bracket, and the number of mounting holes is the same as the number of basic colors of the multi-color light source.

10. A method for fabricating a fiber optic tactile sensor according to claim 8, characterized in that, The following steps are also included between steps S9 and S10: Prepare four tactile units according to steps S1-S9, and assemble them in a 2*2 array; or Prepare 7 tactile units according to steps S1-S9, with 6 tactile units surrounding a central tactile unit.

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