A method of manufacturing a structural conforming FBG sensor array

Abstract

The application discloses a kind of manufacturing methods of structural conformal FBG sensing array, it is related to 3D printing and fiber sensing technical field, the method includes: FBG material is loaded into printing needle tube and is fixed on the mechanical arm of five-axis printer;Viscous film is laid on the motion platform of five-axis printer, start five-axis printer and print FBG material on platform surface according to pre-designed path, and control the rotation parameter of motion platform in the printing process, to increase the bending angle of FBG material when printing grating area;The translation parameter of mechanical arm is controlled simultaneously, so that the distance between needle and viscous film in vertical direction is greater than minimum preset distance;The method is based on determining the minimum preset distance between needle and platform when printing, the minimum bending radius of array bending part on viscous film, realizes the plane or curved surface manufacturing of FBG using five-axis printer, with the advantages of low cost, high efficiency, high manufacturing precision, suitable for large-scale sensing array rapid manufacturing.

Description

Technical Field

[0001] This invention relates to the fields of 3D printing and fiber optic sensing technology, and in particular to a method for manufacturing a structurally conformal FBG sensing array. Background Technology

[0002] FBG (Fiber Bragg Grating) is a novel fiber optic sensing element that uses ultraviolet lasers to create periodic refractive index modulation on the fiber core. External forces induce an elastic-optical effect in the FBG, altering its effective refractive index and grating period, leading to reflection of the center wavelength. It boasts superior light transmission performance, high stability, multiplexing capability, power-free operation, high temperature resistance, small size, corrosion resistance, and electromagnetic interference resistance. These characteristics enable it to perform real-time environmental monitoring in harsh or extreme environments.

[0003] The existing method for arranging FBG sensor arrays is to directly and manually paste them together. Since the wavelength sensitivity of FBG is directly related to the installation angle and position, manual operation is prone to introducing deviations, affecting the sensing accuracy. In addition, the time cost required for manual pasting is relatively large, making it unsuitable for the arrangement of large-scale FBG sensor arrays.

[0004] 3D printing technology can be used to achieve rapid integrated manufacturing of FBG sensor arrays. However, commonly used three-axis printers cannot control the bending angle of the FBG during the printing process and can only keep it at 90°. This results in a large stress concentration when printing the grating area, which is prone to breakage and reduces the success rate of FBG sensor array manufacturing. Summary of the Invention

[0005] To address the aforementioned problems and technical requirements, the inventors have proposed a method for manufacturing a conformal FBG sensor array. By adding two degrees of freedom to a traditional three-axis printer, the rotation of the motion platform is controlled during printing to maintain the angle between the FBG and the platform at an appropriate size. This method allows for the precise and rapid arrangement of large-scale FBG sensor arrays with a certain degree of reliability. The technical solution of this invention is as follows:

[0006] A method for manufacturing a conformal FBG sensor array includes the following steps:

[0007] The FBG material is loaded into the printing needle and fixed to the robotic arm of the five-axis printer.

[0008] An adhesive film is laid on the motion platform of a five-axis printer, and a short optical fiber is led out from the needle tip and fixed on the adhesive film to provide initial traction.

[0009] The five-axis printer is started to print FBG material onto the platform surface according to the pre-designed path. During the printing process, the rotation parameters of the motion platform are controlled to increase the bending angle of the FBG material when printing the raster area. At the same time, the translation parameters of the robotic arm are controlled to make the vertical distance between the needle and the adhesive film greater than the minimum preset distance.

[0010] The manufactured conformal FBG sensor arrays with different bending radii are inspected to determine the minimum bending radius of the conformal FBG sensor array on the plane, so as to readjust the printing path.

[0011] The five-axis printer provides translational motion in the xyz directions and rotational motion in the vw directions.

[0012] A further technical solution is that the method also includes:

[0013] A curved shell is fixed on the motion platform of a five-axis printer, and an adhesive film is laid on the surface of the shell. A short optical fiber is led out from the needle and fixed on the adhesive film to provide initial traction.

[0014] The five-axis printer is started to print FBG material onto the shell surface according to the pre-designed path. During the printing process, the rotation parameters of the motion platform are controlled, and when it is about to print to the grating area, the fiber in front of the grating is lifted along the normal of the shell to which it is attached, so as to increase the bending angle of the FBG material when printing the grating area. At the same time, the translation parameters of the robotic arm are controlled so that the vertical distance between the needle and the adhesive film is greater than the minimum preset distance.

[0015] The conformal FBG sensor arrays manufactured on surfaces with different curvatures are examined to determine the maximum bending curvature of the surface in order to reselect the surface shell.

[0016] A further technical solution involves controlling the rotation parameters of the motion platform during the printing process to increase the bending angle of the FBG material when printing the grating area, including:

[0017] When printing straight segments containing grating regions, the rotation angle and direction of the motion platform along the v-axis are controlled according to the movement direction of the robotic arm along the x-axis, with the goal of increasing the bending angle of the FBG material;

[0018] When printing the curved section, control the rotation angle and direction of the motion platform along the v-axis. The goal is to rotate the platform to a horizontal position and control the robotic arm to move along the x-axis and the motion platform to move along the y-axis in the specified directions to complete the printing of the curved section.

[0019] A further technical solution is to control the rotation angle of the motion platform along the v-axis to be between 0° and 30°, corresponding to a bending angle of the FBG material between 90° and 120°.

[0020] A further technical solution involves obtaining the minimum preset distance between the needle tip and the adhesive film in the vertical direction, including:

[0021] Measure the z-axis coordinate z1 corresponding to the moment the needle contacts the adhesive film;

[0022] The z-axis coordinate z2 of the needle tip was measured when the optical fiber broke;

[0023] The difference between coordinates z1 and z2 is used as the minimum preset distance between the needle and the adhesive film in the vertical direction.

[0024] A further technical solution involves inspecting the manufactured conformal FBG sensor arrays with different bending radii to determine the minimum bending radius of the conformal FBG sensor array on the plane, including:

[0025] Determine the minimum bending radius r1 in the conformal FBG sensor array so that the curved portion does not slip or break on the viscous membrane;

[0026] Determine the minimum bending radius r2 in the conformal FBG sensor array that can detect the intensity of reflected light signals;

[0027] Based on radii r1 and r2 and the theoretical minimum bending radius R ′ The size relationship is used to determine the minimum bending radius of the conformal FBG sensor array on the plane.

[0028] Its further technical solution is based on radii r1 and r2 and the theoretical minimum bending radius R ′ The size relationship is used to determine the minimum bending radius of the conformal FBG sensor array on the plane, including:

[0029] If R ′ If the expression is greater than or equal to max{r1,r2}, then select R. ′ As the minimum bending radius of the conformal FBG sensor array on the plane;

[0030] If R ′ If the value is less than or equal to max{r1,r2}, then max{r1,r2} is selected as the minimum bending radius of the conformal FBG sensor array on the plane.

[0031] A further technical solution is that the method also includes:

[0032] Based on the theory that the bending moment generated by the adhesion force on the viscous film of the curved portion of the conformal FBG sensing array is balanced with the bending moment inside the optical fiber, the theoretical minimum bending radius R of the conformal FBG sensing array on the plane is determined. ′ This keeps the curved portion stable on the viscous membrane.

[0033] Its further technical solution is that the theoretical minimum bending radius satisfies:

[0034]

[0035] Where E is the Young's modulus of the conformal FBG sensor array, I is the moment of inertia of the cross section of the conformal FBG sensor array, and τ max Δ represents the adhesion force at the contact point between the curved portion and the straight segment of the conformal FBG sensor array, and Δ represents the contact width between the conformal FBG sensor array and the adhesive film.

[0036] A further technical solution is that the method also includes:

[0037] A five-axis printer is used to spray epoxy resin onto the designated curved sections of the conformal FBG sensor array to stabilize the designated curved sections.

[0038] The beneficial technical effects of this invention are:

[0039] Compared to traditional manual bonding and placement of FBG sensor arrays, the conformal FBG sensor array manufacturing method implemented in this application based on a five-axis printing platform offers higher precision. Furthermore, this method is highly flexible, allowing for adjustments to the sensor array shape as needed, making it suitable for large-scale manufacturing of conformal FBG sensor arrays. Whether printing on a planar or curved surface, given the minimum preset distance between the printing nozzle and the adhesive film, and the minimum bending radius of the FBG sensor array on the planar surface versus the maximum bending curvature of the curved surface, to prevent breakage of the FBG grating area due to excessive stress concentration, the bending angle of the FBG can be indirectly controlled during manufacturing by adjusting the rotation angle and direction of the five-axis printing platform, thereby reducing stress concentration. Appropriate fixing methods are also employed to prevent slippage of the bent portion in practical applications, thus improving the manufacturing success rate of conformal FBG sensor arrays. Attached Figure Description

[0040] Figure 1 This is a flowchart of the manufacturing method of the conformal FBG sensor array provided in this application.

[0041] Figure 2 This is a schematic diagram illustrating the operation of loading the FBG material provided in this application into the printing needle.

[0042] Figure 3 This is a schematic diagram provided in this application for determining the minimum preset distance between the needle and the adhesive film during the printing process.

[0043] Figure 4 This is a schematic diagram of controlling the rotation of the motion platform during the planar printing process provided in this application.

[0044] Figure 5This is a schematic diagram of the FBG sensor array obtained by planar printing provided in this application.

[0045] Figure 6 This is a schematic diagram of the stress on the bent portion of the FBG sensor array provided in this application.

[0046] Figure 7 The wristband provided in this application has Figure 5 The measured dynamic strain change data of the FBG sensor array for motion judgment is shown in the figure.

[0047] Figure 8 This is a schematic diagram of controlling the rotation of the motion platform during the surface printing process provided in this application.

[0048] Figure 9 This is a path design diagram of the curved surface printed FBG sensor array provided in this application. Detailed Implementation

[0049] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0050] Example 1:

[0051] This embodiment provides a method for manufacturing a conformal FBG sensor array. Please refer to [link / reference]. Figure 1 The flowchart shown illustrates the method, which specifically includes the following steps:

[0052] Step 1: Load FBG material into the printing needle and fix it to the robotic arm of the five-axis printer. In this embodiment, the FBG material loading method is determined based on the detachable structure of the selected printing needle. Please refer to [link / reference] for specific loading methods. Figure 2 As shown, the syringe and needle are disassembled and separated. First, FBG material is inserted into the syringe, then into the needle. The syringe and needle are then screwed together to complete the filling. Finally, the syringe filled with FBG material is clamped onto the robotic arm of the five-axis printer. It should be noted that... Figure 2 The gray area represents the optical fiber made of FBG material, and the black area represents the grating area made of FBG material.

[0053] Step Two: Lay an adhesive film on the motion platform of the five-axis printer. This provides initial traction for the conformal manufacturing of the FBG sensor and also serves to fix it in place. In practical applications, the characteristics of different adhesive films can be compared to select one that meets both viscosity requirements and good adhesion to the skin surface, and then laid on the platform. The five-axis printer's motion is controlled to obtain the z-axis coordinates of different positions of the needle in the vertical direction. This coordinate is then used to calculate the minimum preset distance L between the needle and the adhesive film in the vertical direction that should be controlled during the actual manufacturing process.

[0054] The method for obtaining the minimum preset distance L includes: measuring the z-axis coordinate z1 when the needle contacts the adhesive film, measuring the z-axis coordinate z2 of the needle when the optical fiber breaks, and using the difference between coordinates z1 and z2 as the minimum preset distance L between the needle and the adhesive film in the vertical direction. For detailed operating instructions, please refer to [link to instructions]. Figure 3 As shown, firstly, the printing needle without FBG material is lowered until it contacts the adhesive film, and the z-axis coordinate z1 of the needle tip is recorded at this point. Then, FBG material is loaded into the printing needle and connected to the five-axis printer. Using tweezers or similar tools, a short section of optical fiber is led out from the needle tip and pressed and fixed onto the adhesive film. The needle is lowered vertically until the optical fiber breaks, and the z-axis coordinate z2 of the needle tip is recorded at this point. The difference between the obtained z1 and z2 values ​​yields the minimum preset vertical distance L between the needle tip and the adhesive film that should be controlled during the actual manufacturing process. The needle is lowered to a position higher than the minimum preset distance L, and a short section of optical fiber is led out from the needle tip and pressed and fixed onto the adhesive film using tweezers or similar tools to provide initial traction for subsequent manufacturing.

[0055] Step 3: Start the five-axis printer to print FBG material onto the platform surface according to the pre-designed path. During the printing process, control the rotation parameters of the motion platform to increase the bending angle of the FBG material when printing the raster area. At the same time, control the translation parameters of the robotic arm so that the vertical distance between the needle and the adhesive film is greater than the minimum preset distance L. The rotation and translation parameters include both numerical magnitude and direction.

[0056] The five-axis printer used in this embodiment provides translational motion in three directions (x, y, z) and rotational motion in two directions (v, w). The five degrees of freedom are as follows: Figure 4 As shown. The pre-designed printing path can include straight segments and curved segments. When printing straight segments containing the grating area, rotation commands are added to the motion program of the five-axis printer to indirectly control the bending angle of the FBG material during manufacturing. This allows the motion platform to be rotated along the v-axis based on the movement direction of the robotic arm along the x-axis, aiming to increase the bending angle of the FBG material and prevent breakage of the grating area. When printing curved segments, the rotation angle and direction of the motion platform along the v-axis are controlled to rotate the platform to a horizontal position. Simultaneously, the robotic arm moves along the x-axis, and the motion platform moves along the y-axis in specified directions to complete the printing of the curved portion. Optionally, the rotation command sets the rotation angle of the motion platform along the v-axis to 0°-30°, corresponding to a bending angle of the FBG material of 90°-120°.

[0057] Taking the fabrication of an S-shaped FBG sensor array on the platform as an example, please refer to the actual operation process. Figure 4As shown, when the needle moves in the positive x-axis direction, the platform must first be controlled to rotate counterclockwise along the v-axis to a certain angle. After the straight segment is printed, the platform then rotates clockwise along the v-axis to a horizontal position. The robotic arm moves simultaneously along the positive x-axis and the moving platform moves along the negative y-axis to complete the printing of the curved section. When the needle moves in the negative x-axis direction, the platform must first be controlled to continuously rotate clockwise along the v-axis to a certain angle until the straight segment is printed. Repeat this process. For the final product of the manufactured FBG sensor array, please refer to [reference needed]. Figure 5 As shown. This method can effectively reduce stress concentration in the FBG grating region, largely avoiding grating region fracture and improving the success rate of this manufacturing method.

[0058] Step 4: Inspect the manufactured conformal FBG sensor arrays with different bending radii to determine the minimum bending radius of the conformal FBG sensor array on the plane, so as to readjust the printing path. This inspection is conducted based on two aspects: the intensity of reflected light from the FBG sensor array and whether slippage or breakage has occurred in the bent portion.

[0059] Considering that FBG bending leads to optical signal loss, the adhesive film cannot constrain the FBG, causing slippage of the bent portion, and excessive curvature can lead to breakage, the bending radius of the FBG needs to be greater than a limit value (i.e., the minimum bending radius) when designing the printing path. This limit value is obtained by: determining the minimum bending radius r1 in the conformal FBG sensing array that prevents slippage and breakage on the adhesive film; determining the minimum bending radius r2 in the conformal FBG sensing array that can detect the intensity of reflected optical signals; and comparing radii r1 and r2 with the theoretical minimum bending radius R. ′ The relationship between the sizes of r1, r2, and R is used to determine the minimum bending radius of the conformal FBG sensor array on the plane. ′ The specific steps for comparing sizes include:

[0060] (1) Print FBGs with different bending radii on the adhesive film using a five-axis printer. Arrange them in order of bending radius from large to small. After placing them in the air for a period of time, observe whether the bent parts of the FBGs with each bending radius break or slip. The smallest bending radius that does not slip or break is taken as r1.

[0061] (2) Connect the manufactured FBG sensor array to, for example... Figure 5 The demodulator shown is used to observe whether the intensity of the light signal reflected by the FBG sensor array on the plane can be detected by the demodulator, and the minimum bending radius that can be detected by the demodulator is taken as r2.

[0062] (3) After determining the minimum bending radius r1 that does not slip or break and the minimum bending radius r2 that the light intensity signal at the sensor array output can be detected, if the theoretical minimum bending radius R ′ If the expression is greater than or equal to max{r1,r2}, then select R. ′ As the minimum bending radius of the conformal FBG sensing array on the plane; if R ′ If the value is less than or equal to max{r1,r2}, then max{r1,r2} is selected as the minimum bending radius of the conformal FBG sensor array on the plane.

[0063] In this embodiment, based on the theory that the bending moment generated by the adhesion force of the curved portion of the conformal FBG sensing array on the adhesive film is balanced with the bending moment inside the optical fiber, the theoretical minimum bending radius R of the conformal FBG sensing array on the plane is determined. ′ This allows the curved portion to remain stable on the adhesive membrane. ′ The detailed derivation process includes: Please refer to... Figure 6 As shown, the FBG generates an adhesive force along the normal direction at the contact portion with the adhesive film. Assuming the magnitude of the adhesive force is the same along the radial cross-section, its magnitude distribution along its circumferential direction q is τ = τ max ·cosθ, where τ Max Let be the magnitude of the adhesive force at the contact point between the curved section and the straight section. The magnitude of the bending moment generated at the center of symmetry of the FBG along the bending angle α is:

[0064] The infinitesimal element dA of the contact area contact =Δ·ds=Δ·R·dθ, and by integration, the bending moment per unit angle can be obtained as Where R is the bending radius of FBG, and Δ is the contact width between FBG and the adhesive film.

[0065] When the fiber optic cable (FBG) is bent, it has an internal bending moment M² = EI / R per unit angle, where E is the Young's modulus of the FBG and I is the moment of inertia of the FBG cross-section. To maintain the FBG in its bent state and prevent slippage, the bending moment generated by the adhesive force per unit angle must be balanced with the internal bending moment of the optical fiber, i.e.:

[0066] Since within the interval (0, 2π) The maximum value of approaches 1 infinitely, while in practical applications the bending radius R is taken to be ≥ 1 mm, therefore Therefore, the minimum bending radius R′ that keeps the bent portion of the FBG stable must satisfy:

[0067]

[0068] Optionally, an appropriate fixing method can be used to fix the curved portion of the manufactured FBG sensor array to prevent deformation of the curved portion from compromising sensor accuracy in practical applications. In this embodiment, after manufacturing, without affecting the measurement results, epoxy resin is sprayed onto the designated curved portion (e.g., an area with a small bending radius) of the conformal FBG sensor array using a five-axis printer to stabilize the designated curved portion.

[0069] Step 5: Place the conformal FBG sensor array manufactured above onto the surface of the object under test, and measure the dynamic strain change data of the object's surface to verify the reliability of the manufacturing method based on rapid integration of the FBG sensor array using a five-axis printer. The reliability test process includes: attaching the manufactured FBG sensor array to the tester's wrist, and measuring the strain data when the hand is stationary and when performing gestures 1 to 3. Each gesture is performed eight times. If the strain signal change of the FBG for the same gesture shows a certain regularity and the strain signal changes of the FBG for different gestures show certain differences, it proves that the sensor array has a certain degree of reliability in practical applications. Please refer to the measurement results. Figure 7 As shown in the results, the measured strain data conforms to the above-mentioned pattern, proving that the proposed manufacturing method of rapid integrated FBG sensor array based on a five-axis printer is reliable.

[0070] Example 2:

[0071] This embodiment also provides a method for manufacturing a conformal FBG sensor array. This method further realizes the curved surface printing of the FBG sensor array based on the planar printing of the FBG sensor array provided in Embodiment 1.

[0072] Step Two: Fix a curved shell onto the motion platform of the five-axis printer, and lay an adhesive film on the shell surface. Lead a short section of optical fiber from the needle tip and fix it to the adhesive film to provide initial traction. The specific method for fixing the curved shell to the five-axis printing platform and ensuring stable adhesion of the FBG to the shell surface is as follows: Use double-sided adhesive to attach the bottom surface of the shell to the five-axis printing platform to prevent changes in the relative position of the shell during printing, which would affect printing accuracy. Utilizing the double-sided adhesive properties of the nano-adhesive, it is attached to the outer surface of the shell, thus ensuring stable adhesion of the FBG to the shell surface.

[0073] Step 3: Start the five-axis printer to print FBG material onto the shell surface according to the pre-designed path. During the printing process, control the rotation parameters of the motion platform and lift the fiber in front of the grating along the normal direction of the shell to which it is attached when printing to the grating area, so as to increase the bending angle of the FBG material when printing the grating area. At the same time, control the translation parameters of the robotic arm so that the vertical distance between the needle and the adhesive film is greater than the minimum preset distance.

[0074] Taking the fabrication of a helical FBG sensor array on the surface of a spherical shell as an example, please refer to the actual operation process. Figure 8 As shown, please refer to the print path. Figure 9 As shown, during the printing process, the motion platform is continuously rotated along the w-axis and then rotated counterclockwise along the v-axis to a certain angle. The spatial position of the needle tube is precisely adjusted through multi-axis linkage. Due to the curved surface structure, the bending angle of the FBG sensor array during the manufacturing process of the five-axis printer is always a right angle, resulting in a large stress concentration in the grating area, which is prone to breakage. Therefore, on the one hand, it is necessary to improve the manufacturing process by using tools such as tweezers to pry up a section of optical fiber in front of the grating when it is about to be printed onto the grating area, thereby increasing the bending angle of the grating area and increasing the success rate of printing FBG on curved surfaces. After a period of time, the pried part will naturally fall back onto the spherical shell due to its own weight. On the other hand, it is necessary to ensure that the distance between the needle and the curved area to be printed is not too high, so that the FBG will be affected by gravity and air resistance, resulting in a large deviation in the landing point and affecting the printing accuracy. It is also necessary to ensure that the distance is not too low (such as less than the minimum preset distance L), which may cause the FBG to break or prevent the insertion of tools to control the bending angle of the FBG. Through the above control methods, it is ensured that the material extrusion direction matches the local features of the curved surface, so that the FBG is printed on the surface of the spherical shell according to the pre-designed path.

[0075] Step 4: Inspect the conformal FBG sensor arrays fabricated on surfaces with different curvatures to determine the maximum curvature of the surface, and then reselect the surface shell. The specific implementation method can be found in Step 4 of Embodiment 1, which includes:

[0076] (1) Print FBGs with different curvatures on the adhesive film using a five-axis printer. Arrange them in order of curvature from large to small. After placing them in the air for a period of time, observe whether the curved part of each FBG with different curvatures breaks or slips. The maximum curvature that does not slip or break is taken as k1.

[0077] (2) Connect the manufactured FBG sensor array to the demodulator and observe whether the intensity of the light signal reflected by the FBG sensor array on the curved surface with different curvatures can be detected by the demodulator. The maximum curvature of the light signal intensity that can be detected by the demodulator is taken as k2.

[0078] (3) After determining the maximum bending curvature k1 that does not slip or break and the maximum bending curvature k2 that the light intensity signal at the sensor array output can detect, if the reciprocal of the theoretical minimum bending radius 1 / R ′ If ≤min{k1,k2}, then choose 1 / R. ′ As the maximum curvature of the conformal FBG sensing array on the curved surface; if 1 / R ′ If the value is greater than min{k1,k2}, then min{k1,k2} is selected as the maximum curvature of the conformal FBG sensor array on the surface.

[0079] It should be noted that the specific implementation methods of steps one and five of this method can refer to steps one and five in embodiment one, and will not be repeated here. The manufacturing methods of FBG sensor arrays based on five-axis printers provided in the above two embodiments have the advantages of low cost, high efficiency, and high manufacturing precision, and are suitable for the rapid manufacturing of large-scale sensor arrays.

[0080] The above descriptions are merely preferred embodiments of this application, and the present invention is not limited to the above embodiments. It is understood that other improvements and variations directly derived or conceived by those skilled in the art without departing from the spirit and concept of the present invention should be considered to be included within the protection scope of the present invention.

Claims

1. A method for manufacturing a structurally conformal FBG sensor array, characterized in that, The method includes: The FBG material is loaded into the printing needle and fixed to the robotic arm of the five-axis printer. An adhesive film is laid on the motion platform of the five-axis printer, and a short optical fiber is led out from the needle and fixed on the adhesive film to provide initial traction force. The five-axis printer is started to print the FBG material onto the platform surface according to a pre-designed path. During the printing process, the rotation parameters of the motion platform are controlled to increase the bending angle of the FBG material when printing the grating area. At the same time, the translation parameters of the robotic arm are controlled so that the vertical distance between the needle and the adhesive film is greater than the minimum preset distance. The manufactured conformal FBG sensor arrays with different bending radii are inspected to determine the minimum bending radius of the conformal FBG sensor array on the plane, so as to readjust the printing path. The five-axis printer provides xyz Translational motion in three directions and vw Rotational motion in two directions; The method for determining the minimum bending radius includes: Determine the minimum bending radius r1 in which the curved portion of the conformal FBG sensing array does not slip or break on the viscous membrane; Determine the minimum bending radius r2 in the conformal FBG sensor array that can detect the intensity of the reflected light signal; Based on radii r1 and r2 and the theoretical minimum bending radius The size relationship is used to determine the minimum bending radius of the conformal FBG sensing array on the plane, including: like If the value is greater than or equal to max{r1,r2}, then select... As the minimum bending radius of the conformal FBG sensing array on the plane; like If <max{r1,r2}, then max{r1,r2} is selected as the minimum bending radius of the conformal FBG sensor array on the plane; Among them, the theoretical minimum bending radius is determined. The methods include: Based on the theory that the bending moment generated by the adhesion force on the adhesive film of the curved portion of the conformal FBG sensing array is balanced with the bending moment inside the optical fiber, the theoretical minimum bending radius of the conformal FBG sensing array on the plane is determined. This keeps the curved portion stable on the adhesive film; The theoretical minimum bending radius satisfies: in, E The Young's modulus of the conformal FBG sensor array is given. I The moment of inertia of the conformal FBG sensor array cross section, The magnitude of the adhesive force at the contact point between the curved portion and the straight segment of the conformal FBG sensor array. The contact width between the conformal FBG sensing array and the adhesive membrane.

2. The method for manufacturing a conformal FBG sensor array according to claim 1, characterized in that, The method further includes: A curved shell is fixed to the motion platform of the five-axis printer, and an adhesive film is laid on the surface of the shell. A short optical fiber is led out from the needle and fixed on the adhesive film to provide initial traction. The five-axis printer is started to print the FBG material onto the surface of the housing according to a pre-designed path. During the printing process, the rotation parameters of the motion platform are controlled, and when the grating area is about to be printed, the fiber in front of the grating is lifted along the normal direction of the housing to which it is attached, so as to increase the bending angle of the FBG material when printing the grating area. At the same time, the translation parameters of the robotic arm are controlled so that the vertical distance between the needle and the adhesive film is greater than the minimum preset distance. The conformal FBG sensor arrays manufactured on surfaces with different curvatures are examined to determine the maximum bending curvature of the surface in order to reselect the surface shell.

3. The method for manufacturing a conformal FBG sensor array according to claim 1, characterized in that, Controlling the rotation parameters of the motion platform during the printing process to increase the bending angle of the FBG material when printing the grating area includes: When printing a straight line segment containing the raster region, according to the robotic arm along... x The direction of axis movement controls the motion platform along... v The rotation angle and direction of the shaft are aimed at increasing the bending angle of the FBG material; During the printing of the curved section, the motion platform is controlled to move along... v The rotation angle and direction of the axis are designed to rotate the platform to a horizontal position and control the robotic arm along... x The axis along which the motion platform is located y The axes move simultaneously in the specified direction to complete the printing of the curved section.

4. The method for manufacturing a conformal FBG sensor array according to claim 3, characterized in that, Control the motion platform along v The rotation angle of the shaft is 0. ° -30 ° The corresponding FBG material has a bending angle of 90 degrees. ° -120 ° .

5. The method for manufacturing a conformal FBG sensor array according to claim 1 or 2, characterized in that, Obtain the minimum preset distance between the needle tip and the adhesive membrane in the vertical direction, including: The z-axis coordinate z1 corresponding to the moment the needle contacts the adhesive membrane is measured; The z-axis coordinate z2 of the needle tip was measured when the optical fiber broke; The difference between coordinates z1 and z2 is taken as the minimum preset distance between the needle and the adhesive film in the vertical direction.

6. The method for manufacturing a conformal FBG sensor array according to claim 1 or 2, characterized in that, The method further includes: The five-axis printer is used to spray epoxy resin onto a designated curved portion of the conformal FBG sensor array to stabilize the designated curved portion.

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