Shape determination method, multi-core optical fiber, electronic device, and

Abstract

The invention provides a shape determination method, which comprises the following steps that: under the condition that a multi-core optical fiber transmits an optical signal, a first central wavelength variation of a first fiber core and a second central wavelength variation of a second fiber core are obtained, the first central wavelength variation reflects the temperature change of the first fiber core, and the second central wavelength variation reflects the temperature change of the second fiber core; the second central wavelength variation reflects the shape change of the second fiber core; compensating a second central wavelength variable quantity of the second fiber core according to the first central wavelength variable quantity of the first fiber core to obtain a target central wavelength variable quantity of the second fiber core, the target central wavelength variable quantity reflecting stress borne by the second fiber core when the shape of the second fiber core is changed; and performing shape construction on the to-be-measured area according to the target center wavelength variable quantity to obtain a target shape of the to-be-measured area. The invention further provides a multi-core optical fiber, electronic equipment and a computer readable medium.

Description

Technical Field

[0001] The present disclosure relates to the field of sensing technologies, and particularly to a method for determining a shape, a multi-core optical fiber, an electronic device, and a computer-readable medium. Background Art

[0002] Shape sensing technology plays an important role in civil facilities, precision machinery, aerospace engineering, and biomedical and medical fields. For example, it is applied to the structural health monitoring of civil infrastructure (buildings, tunnels, bridges, and roads), the reconstruction of the displacement field of key components of precision machinery (flexible wings and aircraft), and tracking robots and medical devices (biopsy needles, medical catheters, and endoscopes) inside the human body.

[0003] Existing fiber-based shape sensing technologies are affected by factors such as temperature, and there is a problem of large errors. Summary of the Invention

[0004] Embodiments of the present disclosure provide a method for determining a shape, a multi-core optical fiber, an electronic device, and a computer-readable medium.

[0005] In a first aspect, embodiments of the present disclosure provide a method for determining a shape, wherein a multi-core optical fiber is attached to a region to be measured. The multi-core optical fiber includes a first core and at least three second cores. The first core is located at the center position of the cross-section of the multi-core optical fiber, and the method includes:

[0006] When an optical signal is transmitted through the multi-core optical fiber, obtaining a first central wavelength change amount of the first core and a second central wavelength change amount of the second core. The first central wavelength change amount reflects the temperature change of the first core, and the second central wavelength change amount reflects the shape change of the second core;

[0007] Compensating the second central wavelength change amount of the second core according to the first central wavelength change amount of the first core to obtain a target central wavelength change amount of the second core, where the target central wavelength change amount reflects the stress received when the second core undergoes a shape change;

[0008] Constructing the shape of the region to be measured according to the target central wavelength change amount to obtain the target shape of the region to be measured.

[0009] In a second aspect, embodiments of the present disclosure provide a multi-core optical fiber for implementing the method for determining a shape according to the first aspect of the embodiments of the present disclosure. The multi-core optical fiber includes:

[0010] A first core;

[0011] At least three second cores, and the first core is located at the center position of the cross-section of the multi-core optical fiber.

[0012] In a third aspect, embodiments of the present disclosure provide an electronic device, including:

[0013] One or more processors;

[0014] A memory storing one or more programs, which when executed by the one or more processors, cause the one or more processors to implement the shape determination method described in the first aspect of the embodiments of the present disclosure.

[0015] In a fourth aspect, embodiments of the present disclosure provide a computer-readable medium storing a computer program, which when executed by a processor, implements the shape determination method described in the first aspect of the embodiments of the present disclosure.

[0016] The shape determination method provided by the embodiments of the present disclosure utilizes the shape characteristics of the core. The first core is located at the center position of the cross-section of the multi-core optical fiber. Thus, when the multi-core optical fiber is deformed, the lengths of at least three second cores are all affected by strain, while the relationship between the length of the first core and the length of each second core remains relatively unchanged before and after the shape change of the multi-core optical fiber. The change amount of the first central wavelength of the first core reflects the temperature change of the first core. Therefore, the first core can be used to perform temperature compensation on the second cores, directly removing the influence caused by temperature from the change amount of the second central wavelength, that is, eliminating the influence of temperature error on shape determination, and reducing the system complexity. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Is a flowchart of a shape determination method provided by an embodiment of the present disclosure;

[0018] Figure 2 Is a schematic layout structure diagram of a multi-core optical fiber provided by an embodiment of the present disclosure;

[0019] Figure 3 Is another schematic layout structure diagram of a multi-core optical fiber provided by an embodiment of the present disclosure;

[0020] Figure 4 Is a cross-sectional schematic diagram of the layout structure of the cores in a multi-core optical fiber provided by an embodiment of the present disclosure;

[0021] Figure 5 Shows a schematic diagram of the effect of optical signal transmission in the second core;

[0022] Figure 6 Is a flowchart of a specific implementation method of step S3 in an embodiment of the present disclosure;

[0023] Figure 7 Is a flowchart of a specific implementation method of step S32 in an embodiment of the present disclosure;

[0024] Figure 8 It is a flowchart of a specific implementation method for step S321 in the embodiments of the present disclosure;

[0025] Figure 9 It is a diagram of the geometric relationship of the cores in the cross-section when the multi-core optical fiber undergoes a shape change in the embodiments of the present disclosure;

[0026] Figure 10 It is a schematic structural diagram of an electronic device provided by the embodiments of the present disclosure;

[0027] Figure 11 It is a schematic structural diagram of a computer-readable medium provided by the embodiments of the present disclosure;

[0028] Figure 12 It is a schematic diagram of an exemplary application scenario provided by the embodiments of the present disclosure;

[0029] Figure 13 It is a flowchart of a shape determination method provided by the embodiments of the present disclosure. Detailed implementation manners

[0030] To enable those skilled in the art to better understand the technical solutions of the present disclosure, the control method, electronic device, and computer-readable medium provided by the present disclosure will be described in detail below with reference to the accompanying drawings.

[0031] In the following, example embodiments will be described more fully with reference to the accompanying drawings. However, the example embodiments can be embodied in different forms and should not be construed as limited to the embodiments set forth herein. On the contrary, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0032] In the case of no conflict, the various embodiments of the present disclosure and the various features in the embodiments can be combined with each other.

[0033] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0034] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. As used herein, the singular forms "a" and "the" are also intended to include the plural forms unless the context clearly indicates otherwise. It will also be understood that when the terms "comprises" and / or "is made of" are used in this specification, it specifies the presence of the stated features, wholes, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their groups.

[0035] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art. It will also be understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and this disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0036] In some cases, it is necessary to detect the shape of the area to be measured, where the area to be measured can be a flexible surface. A flexible surface refers to the surface of any object that can be bent or deformed, such as a soft robot, a curved pipe, the surface of a structural object, etc. The surface of the object structure can change its shape according to the action of force due to its flexibility.

[0037] Shape sensing technologies are mainly divided into two categories: electrical-based and optical-based. They are both achieved through indirect or direct sensing of stress and strain measurements. For example, for electrical-based shape sensing technology, there are resistive sensors. The materials and device performance of traditional resistive sensors change with time and environment, are vulnerable to the influence of electric fields, magnetic fields, vibrations, radiation, air pressure, sound pressure, air flow, etc., are not suitable for long-term monitoring, and the wiring of resistive strain sensors is complex, with limitations in terms of weight, temperature, and electromagnetic interference resistance, resulting in relatively large measurement errors. Another example is that for sensors based on both electrical and optical shape sensing technologies, there are optoelectronic sensors. Optoelectronic sensors have the advantages of being interference-free and having high-speed transmission capabilities compared to traditional resistive sensors and are widely used. Some optoelectronic sensors have problems with poor electromagnetic compatibility due to the large number of electronic devices they use.

[0038] However, another part of optoelectronic sensors uses multi-core optical fibers to detect the shape of the area to be measured. Since they do not require the use of a large number of electronic devices, they have good electromagnetic interference resistance. The optoelectronic sensor includes multi-core optical fibers. There are multiple cores (i.e., the first core and the second core) with fiber gratings in the multi-core optical fibers. A fiber grating is a region in the optical fiber where a periodic refractive index change is inscribed. When an optical signal passes through, a specific wavelength of light (i.e., the reflected light) will be reflected, while light of other wavelengths will continue to propagate. When the shape of the core changes (such as stretching or compression), the physical parameters of the fiber grating (such as the periodicity or length of the grating, etc.) will also change, resulting in a change in the wavelength of the reflected light. When performing shape detection, by measuring the change in the wavelength of the reflected light, the shape change of the core can be determined. The multi-core optical fiber is attached to the surface of the area to be measured, and the shape of the multi-core optical fiber matches the surface shape of the area to be measured. By detecting the shape of the multi-core optical fiber attached to the surface of the area to be measured, the shape of the surface of the area to be measured can be measured.

[0039] However, the wavelength of the reflected light of the fiber grating not only changes due to shape strain, but also is affected by temperature, resulting in the wavelength of the reflected light being unable to accurately reflect the shape change. Therefore, when determining the change in the area to be measured by the change in the wavelength of the reflected light, the influence of the temperature factor should be excluded, so that the measured shape is more accurate.

[0040] Figure 1 The flowchart of a shape determination method provided by an embodiment of the present disclosure. In a first aspect, referring to Figure 1 , an embodiment of the present disclosure provides a shape determination method, wherein a multi-core optical fiber is attached to the area to be measured. The multi-core optical fiber includes a first core and at least three second cores. The first core is located at the center of the cross-section of the multi-core optical fiber and includes:

[0041] S1. When an optical signal is transmitted through the multi-core optical fiber, obtain a first central wavelength change amount of the first core and a second central wavelength change amount of the second core. Among them, the first central wavelength change amount reflects the temperature change of the first core, and the second central wavelength change amount reflects the shape change of the second core.

[0042] S2. Compensate the second central wavelength change amount of the second core according to the first central wavelength change amount of the first core to obtain a target central wavelength change amount of the second core. Among them, the target central wavelength change amount reflects the stress received when the second core undergoes a shape change.

[0043] S3. Construct the shape of the area to be measured according to the target central wavelength change amount to obtain the target shape of the area to be measured.

[0044] In an embodiment of the present disclosure, a multi-core optical fiber is attached to the area to be measured, and the core shape sensing in the multi-core optical fiber is used. The multi-core optical fiber includes a first core and at least three second cores. Multiple segments of the first core and the second core form a fiber Bragg grating (FBG for short). Among them, the number of first cores in one multi-core optical fiber is one, and the number of second cores is three or more.

[0045] In the case of a shape change in the area to be measured, the shape change of the second core in the multi-core optical fiber attached to the area to be measured will be reflected in the change amount of the second central wavelength. Specifically, the refractive index and period of the fiber grating of the second core will change due to the combined effects of strain and temperature, resulting in a change in the Bragg wavelength (i.e., the central wavelength) of the reflected light of the second core. The temperature change of the first core in the multi-core optical fiber will be reflected in the change amount of the first central wavelength. Specifically, the refractive index and period of the fiber grating of the first core will change due to the influence of temperature, resulting in a change in the Bragg wavelength of the reflected light of the first core. Also, when the multi-core optical fiber undergoes a shape change, the relationship between the length of the first core and the length of each second core remains relatively unchanged before and after the shape change of the multi-core optical fiber, that is, the change in its Bragg wavelength is not affected by strain. Therefore, the change amount of the second central wavelength of the second core can be compensated based on the change amount of the first central wavelength of the first core, directly removing the influence caused by temperature from the change amount of the second central wavelength to obtain the target change amount of the central wavelength, reducing the system complexity. And since the number of second cores is three or more, the target change amounts of the central wavelength corresponding to each second core can be the same or different. Therefore, the target shape can be reconstructed based on the target change amounts of the central wavelength of at least two second cores in the multi-core optical fiber attached to the area to be measured.

[0046] It should be noted that the laying direction of the multi-core optical fiber can be along the length direction of the area to be measured or along the width direction of the area to be measured, but it is not limited to this. The embodiments of the present disclosure do not make specific limitations in this regard. By measuring the wavelengths of the optical signals reflected by the fiber gratings of the multi-core optical fibers in different laying directions, the strain distribution in at least one direction of the area to be measured can be obtained, and then the shape of the area to be measured can be constructed to obtain the target shape. Among them, each laying direction corresponds to a multi-core optical fiber. That is to say, the number of multi-core optical fibers attached to the area to be measured can be one or more. The embodiments of the present disclosure do not make specific limitations in this regard, and the multi-core optical fibers can be attached to the area to be measured in various preset shapes. The embodiments of the present disclosure also do not make specific limitations in this regard. In addition, those skilled in the art should know that the more the number of multi-core optical fibers attached to the area to be measured in different laying directions, the smaller the reconstruction error of the constructed target shape.

[0047] In the process of constructing the target shape in the embodiments of the present disclosure, a large number of electronic devices are not required, and it has a good anti-electromagnetic interference effect.

[0048] Figure 2 It is a schematic diagram of the laying structure of a multi-core optical fiber provided by an embodiment of the present disclosure. Refer to Figure 2, as an example, the starting optical fiber segment A1 of the multi-core optical fiber is arranged along the length direction of the flexible surface, and A1, B1, C1, and D1 are all optical fiber segments arranged along this arrangement direction. Among them, the dotted line is the sub-optical fiber segment used to connect two optical fiber segments, and the A1 segment is the starting optical fiber segment.

[0049] Figure 3 This is a schematic diagram of the layout structure of another multi-core optical fiber provided by the embodiments of the present disclosure. Refer to Figure 3 , as another example, the starting optical fiber segment A2 of the multi-core optical fiber is arranged along the width direction of the flexible surface, and A2, B2, C2, and D2 are all optical fiber segments arranged along this arrangement direction. Among them, the dotted line is the sub-optical fiber segment used to connect two optical fiber segments, and the A2 segment is the starting optical fiber segment.

[0050] Figure 4 This is a cross-sectional schematic diagram of the layout structure of the cores in a multi-core optical fiber provided by the embodiments of the present disclosure. Refer to Figure 4 , as an example, the multi-core optical fiber includes one first core and three second cores. Among them, the first core is the central core 4 located at the center, and the second cores are the three outer edge cores 1, outer edge core 2, and outer edge core 3 arranged around the central core in this cross-sectional schematic diagram.

[0051] The first core is the central core 4 because when the multi-core cores change with the shape of the area to be measured, the relationship between the length of the core at this position and the length of the second core will not be affected before and after the shape change of the multi-core optical fiber, and the change in the central wavelength of the reflected light of the central core 4 is only affected by temperature. The second cores are the three outer edge cores 1, outer edge core 2, and outer edge core 3 arranged around the central core because when the multi-core cores change with the shape of the area to be measured, the change in the central wavelength of the reflected light of these cores is affected by both strain and temperature. Therefore, temperature compensation for the wavelength of the second core can be achieved through the wavelength of the first core.

[0052] Correspondingly, in some embodiments, before S1, it further includes:

[0053] Obtain the first initial central wavelength of the first core and the second initial central wavelength of the second core; wherein, the first initial central wavelength is the central wavelength of the first core when the multi-core optical fiber has not undergone a shape change, and the second initial central wavelength is the central wavelength of the second core when the multi-core optical fiber has not undergone a shape change.

[0054] In the embodiments of the present disclosure, when the multi-core optical fiber has not undergone a shape change refers to the shape state when the first initial central wavelength and the second initial central wavelength are obtained.

[0055] In some embodiments, obtaining the first initial central wavelength of the first core and the second initial central wavelength of the second core includes:

[0056] Obtaining the first initial central wavelength of the first core, and determining the second initial central wavelength according to the effective refractive index and grating period of the second core.

[0057] Figure 5 The schematic diagram of the effect of the optical signal transmitted in the second core is shown. Refer to Figure 5 , in this embodiment, when the optical signal is transmitted in the core of the multi-core optical fiber, the incident light enters the fiber grating with a grating period of λ. Since the fiber grating can strongly reflect the light with the wavelength centered at the Bragg wavelength (i.e., the reflected light), and the light with other wavelengths (i.e., the transmitted light) will be transmitted through, the relationship between the central wavelength of the second core and the effective refractive index and grating period is formula (1):

[0058] λ B = 2nλ (1)

[0059] Wherein, n is the effective refractive index of the corresponding core, λ is the grating period of the corresponding core, and λ B is the central wavelength of the corresponding core.

[0060] Through formula (1), when the multi-core optical fiber does not change in shape, the second initial central wavelength can be determined according to the effective refractive index and grating period of the second core.

[0061] In addition, in the embodiments of the present disclosure, there is no special limitation on the way to obtain the first initial central wavelength of the first core, which can be obtained by measurement, but is not limited thereto.

[0062] In some embodiments, S1 includes:

[0063] Determining the first central wavelength change amount according to the first initial central wavelength of the first core and the first temperature change amount.

[0064] And determining the second central wavelength change amount according to the second initial central wavelength, strain change amount and second temperature change amount of the second core.

[0065] In this embodiment, for the second core, when its shape changes, the stress acting on the second core will change, the effective refractive index and period of the fiber grating in the second core are both modulated, and the Bragg wavelength (i.e., the first initial central wavelength) of the reflected light of the fiber grating in the second core will change. At the same time, the second central wavelength change amount is also affected by temperature. The second central wavelength change amount reflects the change amount of the central wavelength of the reflected light of the fiber grating in the second core relative to the second initial central wavelength.

[0066] In some embodiments, the change amount of the second central wavelength is determined by formula (2):

[0067]

[0068] wherein, Δλ B1 is the change amount of the second central wavelength, K ε is the first constant, is the second constant, Δε is the strain change amount, and ΔT1 is the second temperature change amount.

[0069] For the first core located at the central position of the cross-section of the multi-core optical fiber, when its shape changes, the relationship between the length of its core and the length of the second core will not be affected before and after the shape change of the multi-core optical fiber, and the stress will not change either. When the multi-core optical fiber transmits an optical signal, the change of the effective refractive index and period on the first core is only related to the first temperature change amount, and the change amount of the first central wavelength reflects the change amount of the central wavelength of the reflected light of the first core relative to the first initial central wavelength.

[0070] In some embodiments, the change amount of the first central wavelength is determined by formula (3):

[0071]

[0072] wherein, Δλ B2 is the change amount of the first central wavelength, is the third constant, and ΔT2 is the first temperature change amount.

[0073] Correspondingly, in some embodiments, S2 includes:[[]]

[0074] Determine the target central wavelength change amount of the second core as the difference between the second central wavelength change amount of the second core and the first central wavelength change amount of the first core.

[0075] In this embodiment, for the second core affected by both strain and temperature and the first core not affected by strain, subtracting the first central wavelength change amount of the first core from the second central wavelength change amount of the second core, so that the obtained difference can effectively reflect the stress suffered by the second core when its shape changes, thereby realizing temperature compensation for the second central wavelength change amount of the second core.

[0076] Figure 6 This is a flowchart of a specific implementation method for step S3 in the embodiments of the present disclosure. Refer to Figure 6 In some embodiments, S3 includes:[[]]

[0077] S31. Determine geometric information according to the target central wavelength change amount of each second core.

[0078] S32. Construct curves for all the optical fiber segments in each of the second cores according to the target central wavelength change amount and geometric information of each of the second cores.

[0079] S33. Perform shape construction on the region to be measured according to all the curves to obtain the target shape of the region to be measured.

[0080] In this embodiment, the geometric information is used to describe the shape characteristics of the curve corresponding to the second core. For example, curvature, torsion, etc. First, construct the curve of one optical fiber segment corresponding to the second core according to the geometric information, and then determine the curves of other segmented optical fiber segments through position conversion. Thus, perform shape construction on the region to be measured according to the curves of all the second cores to obtain the target shape. In some embodiments, perform shape construction on the region to be measured through the Nubrs (Non-Uniform Rational B-Spline) algorithm according to the curves, so as to reconstruct the target shape of the region to be measured.

[0081] In some embodiments, when the geometric information is curvature and torsion, the geometric information can be calculated through formulas (4) to (8):

[0082]

[0083]

[0084] θ = angle(κ app ) (6)

[0085] τ(s) = θ′(s) (7)

[0086]

[0087] where ε i is the strain value of the optical fiber segment in the second core, κ is the curvature scalar, j is the first vector unit, k is the second vector unit, θ b and θ are the bending angles of the optical fiber segment, θ i is the angle between the second core and the first core, κ app is the apparent curvature vector, τ(s) is the torsion, r i is the distance between the second core and the first core. Among them, the strain value ε i of the optical fiber segment in the second core can be inversely deduced through formula (2) and the target central wavelength change amount.

[0088] Among them, the optical fiber segments on each second core are relatively aligned. Due to the certain thickness of the multi-core optical fiber, each second core is located at different positions in the multi-core optical fiber (such as Figure 4As shown, when the overall multi-core optical fiber is deformed, the shape changes of each second core are different, that is, the change amounts of the central wavelengths are different. Through formulas (4) to (8), the relevant parameter values (strain values, bending radii, etc.) of the corresponding optical fiber segments in at least three second cores are required to solve for its curvature and torsion. Further, by combining the deformations of multiple optical fiber segments (the parameter values of different optical fiber segments are different, that is, the change amounts of the central wavelengths are different), the overall shape of the multi-core optical fiber can be obtained.

[0089] In some embodiments, a multi-core optical fiber with four second cores is used for measurement to reduce the influence of strain measurement errors on the measurement and balance the calculation amount and the size of the system structure.

[0090] Figure 7 This is a flowchart of a specific implementation method for step S32 in the embodiments of the present disclosure. Refer to Figure 7 In some embodiments, S32 includes:

[0091] S321. Determine the curve of the i-th optical fiber segment in the second core according to the target central wavelength change amount and geometric information of the second core, where the total number of optical fiber segments in the second core is n, both i and n are integers, and 0 < i ≤ n.

[0092] S322. Obtain the relative position relationship between the i-th optical fiber segment and other optical fiber segments.

[0093] S323. Perform position conversion processing on the curve of the i-th optical fiber segment according to the relative position relationship to obtain the corresponding curves of other optical fiber segments.

[0094] In this embodiment, according to the target central wavelength change amount and geometric information of the second core, the curve of the optical fiber segment can be determined through the Frenet frame. Since large reconstruction errors caused by the jump of the normal vector occur when the Frenet frame calculates the reconstructed curve with a jump in the bending of the space curve, therefore, in the case of determining the curve of the i-th optical fiber segment, according to the relative position relationship between the i-th optical fiber segment and other optical fiber segments, position conversion processing is performed on the curve to obtain the corresponding curves of other optical fiber segments. This way of determining the curve in segments can effectively avoid excessive reconstruction errors.

[0095] Refer to Figure 2 In some embodiments, there are 4 optical fiber segments in the second core. The three-dimensional curve coordinates of the A1-th optical fiber segment are determined as X A1 (s), and position conversion processing is performed through formulas (9) to (11):

[0096] X B1 (s) = D B1 X A1(0) (9)

[0097] X C1 (s) = D C1 X A1 (0) (10)

[0098] X D1 (s) = D D1 X A1 (0) (11)

[0099] wherein, X A1 (s) is the three - dimensional curve coordinate of the optical fiber segment of the first A1 segment, D B1 is the first transformation matrix of the optical fiber segment of the first B1 segment, D C1 is the second transformation matrix of the optical fiber segment of the first C1 segment, D D1 is the third transformation matrix, X B1 (s) is the three - dimensional curve coordinate of the optical fiber segment of the first B1 segment, X Cl (s) is the three - dimensional curve coordinate of the optical fiber segment of the first C1 segment, X D1 (s) is the three - dimensional curve coordinate of the optical fiber segment of the first D1 segment, X A1 (0) is the three - dimensional curve coordinate of the optical fiber segment of the first A1 segment when s takes the value of 0; each transformation matrix reflects the relative position relationship between the optical fiber segment of this segment and the optical fiber segment of the first A1 segment. Similarly, the three - dimensional curve coordinates of the optical fiber segments of the first A2 segment, the first B2 segment, the first C2 segment, and the first D2 segment in Figure 3 can be determined.

[0100] Figure 8 This is a flowchart of a specific implementation method of step S321 in the embodiment of the present disclosure. Referring to Figure 8 , in some embodiments, when the geometric information is curvature and torsion, S321 includes:

[0101] S3211. Determine the curve matrix and bending matrix of the i - th optical fiber segment according to the curvature and the torsion; wherein, the curve matrix is a matrix about the tangent vector, the principal normal vector, the binormal vector, and the curve corresponding to the i - th optical fiber segment, the bending matrix is a matrix about the curvature and the torsion, the direction of the tangent vector is the instantaneous movement direction of the second core, and the directions of the principal normal vector and the binormal vector both point to the center of curvature of the curvature.

[0102] S3212. Determine the curve of the i - th optical fiber segment according to the relationship between the curve matrix and the bending matrix.

[0103] Figure 9 This is a diagram of the geometric relationship of the cores in the cross - section when the multi - core optical fiber in the embodiment of the present disclosure undergoes shape change. Referring to Figure 4 and Figure 9, in some embodiments, the cores 1, 2, and 3 (all are the second cores) are provided, and the vertical distances of the cores 1, 2, and 3 from the neutral plane are d1, d2, and d3 in sequence. The linear distances from the center core of the multi-core optical fiber to the cores 1, 2, and 3 are r, and θ b is the bending angle of the optical fiber segment, and θ1 is the included angle between the core 1 and the center core. Solve the differential equations for the formulas (11) to (13) to reconstruct the shape of the i-th optical fiber segment:

[0104]

[0105]

[0106]

[0107] wherein, T(s) is the tangent vector of the instantaneous motion direction of the curve, and the direction of this tangent vector is the instantaneous motion direction of the second core; N(s) is the principal normal vector pointing to the center of curvature, and the direction of this principal normal vector is the direction pointing to the center of the curvature circle of the curvature; B(s) is the binormal vector pointing to the center of curvature, and the direction of this binormal vector is the direction pointing to the center of the curvature circle of the curvature; A(s) is the curve matrix; κ(s) is the curvature, τ(s) is the torsion, C(s) is the bending matrix, and X A (s) is the three-dimensional curve coordinate of the A-th optical fiber segment, wherein A is an integer taking values from 1 to n.

[0108] In the above embodiments of the present disclosure, by using the shape characteristics of the cores, the first core is located at the central position of the cross-section of the multi-core optical fiber. Thus, when the multi-core optical fiber is deformed, the relationship between the length of the first core and the length of the second core will not be affected before and after the shape change of the multi-core optical fiber. The change amount of the first central wavelength of the first core reflects the temperature change of the first core. Therefore, the temperature compensation for the second core can be performed through the first core, directly removing the influence caused by temperature from the change amount of the second central wavelength, that is, eliminating the influence of temperature error on the shape determination, and reducing the system complexity. At the same time, in the process of curve shape reconstruction, a segmented calculation method is adopted, avoiding the excessive reconstruction error caused by the jump of the normal vector when the space curve bends and jumps during the reconstruction of the curve by the Frenet frame calculation.

[0109] Compared with some related technologies, for example, the shape sensing technology based on the electromechanical system needs to rigidly connect a large number of accelerometer nodes and design complex reconstruction tracking algorithms, which is very limited by the embedding ability, has poor flexibility and low resolution, and has poor corrosion resistance. In addition, the equipment of the shape monitoring technology based on image vision has a large volume and is suitable for tracking the shape of large objects. In a scenario with limited volume, it is difficult to be integrated and work stably.

[0110] The above embodiments of the present disclosure are applicable to application scenarios such as aircraft shape monitoring, flight state detection, intelligent material deformation monitoring, human motion monitoring, and intelligent robot posture monitoring.

[0111] Second solution, an embodiment of the present disclosure provides a multi-core optical fiber for implementing the shape determination method described in the first aspect of the embodiments of the present disclosure. Among them, the multi-core optical fiber includes:

[0112] A first core;

[0113] At least three second cores, and the first core is located at the central position of the cross-section of the multi-core optical fiber.

[0114] In a third aspect, referring to Figure 10 , an embodiment of the present disclosure provides an electronic device, which includes:

[0115] One or more processors 1001;

[0116] A memory 1002, on which one or more programs are stored. When the one or more programs are executed by the one or more processors, the one or more processors implement the shape determination method of any one of the above;

[0117] One or more I / O interfaces 1003, connected between the processor and the memory, configured to implement information interaction between the processor and the memory.

[0118] Among them, the processor 1001 is a device with data processing capabilities, including but not limited to a central processing unit (CPU), etc.; the memory 1002 is a device with data storage capabilities, including but not limited to a random access memory (RAM, more specifically such as SDRAM, DDR, etc.), a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), a flash memory (FLASH); the I / O interface (read / write interface) 1003 is connected between the processor 1001 and the memory 1002 and can implement information interaction between the processor 1001 and the memory 1002, including but not limited to a data bus (Bus), etc.

[0119] In a fourth aspect, referring to Figure 11 , an embodiment of the present disclosure provides a computer-readable medium, on which a computer program is stored, and when the program is executed by a processor, it implements any one of the above shape determination methods.

[0120] In order to enable those skilled in the art to more clearly understand the technical solutions provided by the embodiments of the present disclosure, the following will detail the technical solutions provided by the embodiments of the present disclosure through specific embodiments:

[0121] Embodiment 1: As Figure 12As shown in the figure, it is a schematic diagram of an exemplary application scenario provided by an embodiment of the present invention. In this application scenario, a pulsed light source is a device capable of emitting pulsed optical signals. An optical circulator is a device that allows optical signals to propagate in only one direction. An optical switch is a device capable of controlling the transmission path of optical signals. An optical fiber grating demodulator (wavelength detection system) is used to measure the reflected wavelengths of the optical fiber gratings in the cores of a multi-core optical fiber. The principle is that an optical fiber grating can strongly reflect optical signals with wavelengths centered around the Bragg wavelength, while optical signals of other wavelengths are transmitted. A signal processing and control system (applied to a memory, a processor, etc.) is used to process and analyze the electrical signals obtained by the optical fiber grating demodulator.

[0122] In this application scenario, the optical signal emitted by the pulsed light source passes through the optical circulator. The optical circulator allows the optical signal to only enter the optical switch, preventing the return optical signal from entering the pulsed light source. The optical switch sequentially selects each optical fiber in the multi-core optical fiber, so that only one optical fiber is selected each time. The optical signal propagates in one optical fiber. In the selected optical fiber, the optical signal is affected by the strain (such as stretching or compression) in the optical fiber, resulting in changes in the propagation speed and / or wavelength of the optical signal. The optical fiber grating demodulator measures the reflected wavelengths (central wavelengths) of the cores in the multi-core optical fiber. The signal processing and control system determines the shape of the multi-core optical fiber based on the measurement values of the optical fiber grating demodulator. It can be understood that other types of optical signals generated by other light source devices can also be applicable to the technical solutions of the embodiments of the present disclosure, and the embodiments of the present disclosure do not make specific limitations in this regard.

[0123] In addition, it should be understood that as Figure 12 shown, the application scenario is optional and not necessary.

[0124] Embodiment 2: Figure 13 It is a flowchart of a shape determination method provided by an embodiment of the present disclosure. Referring to Figure 3 、 4 、5, 12, and 13, in the application scenario as Figure 12 shown, two multi-core optical fibers are attached to the flexible surface of the area to be measured. Each multi-core optical fiber includes a first core and three second cores. The multiple optical fiber segments of the first multi-core optical fiber are arranged in the layout manner as Figure 2 shown (hereinafter referred to as the U-plane arrangement manner), and the multiple optical fiber segments of the second multi-core optical fiber are arranged in the layout manner as Figure 3 shown (hereinafter referred to as the V-plane arrangement manner). The shape of the flexible surface of the area to be measured is reconstructed through the following process:

[0125] Step 1301, sequentially obtain the strain information in the multi-core optical fiber. The strain information is the change amount of the first central wavelength of the first core and the change amount of the second central wavelength of the second core.

[0126] Step 1302: Perform temperature compensation on the strain information (second center wavelength change amount) of the second fiber core through the strain information (first center wavelength change amount) of the first fiber core to obtain the target strain information (target center wavelength change amount).

[0127] Step 1303: Calculate the curvature and torsion of the fiber segment corresponding to the U-plane arrangement or V-plane arrangement of the multi-core optical fiber respectively according to the target strain information of all the second fiber cores.

[0128] Step 1304: Calculate the curve shape of the fiber segment of section A according to the curvature and torsion. Here, section A refers to Figure 3 section A1 in Figure 4 or section A2 in

[0129] Step 1305: Calculate the curve shapes of sections B, C, and D in sequence through coordinate transformation. Among them, section B is section B1 or B2, section C is section C1 or C2, and section D is section D1 or D2.

[0130] Step 1306: Calculate the curved surface shape of the flexible surface of the area to be measured according to the curve shapes corresponding to all the fiber segments.

[0131] Those of ordinary skill in the art will understand that all or some of the steps in the methods disclosed above, and the functional modules / units in the systems and devices, can be implemented as software, firmware, hardware, and appropriate combinations thereof. In the hardware implementation, the division between the functional modules / units mentioned above does not necessarily correspond to the division of physical components; for example, one physical component may have multiple functions, or one function or step may be executed by several physical components in cooperation. Some or all physical components may be implemented as software executed by a processor, such as a central processing unit, a digital signal processor, or a microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, which may include a computer storage medium (or non-transitory medium) and a communication medium (or transitory medium). As is well known to those of ordinary skill in the art, the term computer storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information, such as computer-readable instructions, data structures, program modules, or other data. Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory, or other memory technologies, CD-ROM, digital versatile disk (DVD), or other optical disk storage, magnetic cassettes, tapes, magnetic disk storage, or other magnetic storage devices, or any other medium that can be used to store the desired information and can be accessed by a computer. In addition, as is well known to those of ordinary skill in the art, a communication medium typically includes computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transmission mechanism, and may include any information delivery medium.

[0132] Example embodiments have been disclosed herein, and although specific terms have been used, they are used for and should be construed only as general descriptive meanings and not for purposes of limitation. In some instances, it will be apparent to those skilled in the art that, unless otherwise expressly stated, the features, characteristics, and / or elements described in connection with a particular embodiment may be used alone or in combination with the features, characteristics, and / or elements described in connection with other embodiments. Accordingly, those skilled in the art will understand that various forms and details may be changed without departing from the scope of the disclosure as set forth in the appended claims.

Claims

1. A shape determination method, wherein, The multi-core optical fiber is attached to the area to be measured. The multi-core optical fiber includes a first core and at least three second cores. The first core is located at the center of the cross-section of the multi-core optical fiber, and includes: When the multi-core optical fiber transmits an optical signal, obtain a first central wavelength change amount of the first core and a second central wavelength change amount of the second core. Among them, the first central wavelength change amount reflects the temperature change of the first core, and the second central wavelength change amount reflects the shape change of the second core; Compensate the second central wavelength change amount of the second core according to the first central wavelength change amount of the first core to obtain a target central wavelength change amount of the second core. Among them, the target central wavelength change amount reflects the stress received when the second core undergoes a shape change; Perform shape construction on the area to be measured according to the target central wavelength change amount to obtain the target shape of the area to be measured.

2. The shape determination method according to claim 1, wherein, Before obtaining the first central wavelength change amount of the first core and the second central wavelength change amount of the second core, it further includes: Obtain a first initial central wavelength of the first core and a second initial central wavelength of the second core; among them, the first initial central wavelength is the central wavelength of the first core when the multi-core optical fiber does not undergo a shape change, and the second initial central wavelength is the central wavelength of the second core when the multi-core optical fiber does not undergo a shape change.

3. The shape determination method according to claim 2, wherein, Obtaining the first initial central wavelength of the first core and the second initial central wavelength of the second core includes: Obtain the first initial central wavelength of the first core, and determine the second initial central wavelength according to the effective refractive index and grating period of the second core.

4. The shape determination method according to claim 2, wherein, Obtaining the first central wavelength change amount of the first core and the second central wavelength change amount of the second core includes: Determine the first central wavelength change amount according to the first initial central wavelength of the first core and the first temperature change amount; And determine the second central wavelength change amount according to the second initial central wavelength, strain change amount and second temperature change amount of the second core.

5. The shape determination method according to claim 1, wherein, Compensating the second central wavelength change amount of the second core according to the first central wavelength change amount of the first core to obtain the target central wavelength change amount of the second core includes: Determine the difference between the second central wavelength change amount of the second core and the first central wavelength change amount of the first core as the target central wavelength change amount of the second core.

6. The shape determination method according to claim 1, wherein, Performing shape construction on the area to be measured according to the target central wavelength change amount to obtain the target shape of the area to be measured includes: Determine geometric information according to the target central wavelength change amount of each second core; Construct curves of all optical fiber segments in each second core according to the target central wavelength change amount and geometric information of each second core; Perform shape construction on the area to be measured according to all the curves to obtain the target shape of the area to be measured.

7. The shape determination method according to claim 6, wherein, Constructing curves of all the optical fiber segments in each second core according to the target central wavelength change amount and geometric information of each second core includes: Determine the curve of the i-th optical fiber segment in the second core according to the target central wavelength change amount and geometric information of the second core, where the total number of the optical fiber segments in the second core is n, both i and n are integers, and 0 < i ≤ n; Obtain the relative position relationship between the i-th optical fiber segment and other optical fiber segments; Perform position conversion processing on the curve of the i-th optical fiber segment according to the relative position relationship to obtain the corresponding curves of other optical fiber segments.

8. The shape determination method according to claim 7, wherein, When the geometric information is curvature and torsion, determining the curve of the i-th optical fiber segment in the second core according to the target central wavelength change amount and geometric information of the second core includes: Determine the curve matrix and bending matrix of the i-th optical fiber segment according to the curvature and the torsion; where the curve matrix is a matrix about the tangent vector, the principal normal vector, the binormal vector, and the curve corresponding to the i-th optical fiber segment, the bending matrix is a matrix about the curvature and the torsion, the direction of the tangent vector is the instantaneous motion direction of the second core, and the directions of the principal normal vector and the binormal vector both point to the center of curvature of the curvature; Determine the curve of the i-th optical fiber segment according to the relationship between the curve matrix and the bending matrix.

9. A multi-core optical fiber, wherein, Including: A first core; At least three second cores, and the first core is located at the central position of the cross-section of the multi-core optical fiber.

10. An electronic device, including: One or more processors; A memory, on which one or more programs are stored, and when the one or more programs are executed by the one or more processors, the one or more processors implement the shape determination method according to any one of claims 1 to 8.

11. A computer-readable medium, on which a computer program is stored, and when the program is executed by a processor, it implements the shape determination method according to any one of claims 1 to 8.

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