Three-dimensional force sensor and decoupling method

Abstract

The invention relates to a three-dimensional force sensor and a decoupling method, the sensor comprises an elastic body, the elastic body comprises a first area and a second area along the axial direction, the first area is a beam plate with two ends fixedly connected with the elastic body, and the second area is a hollow pipe with two ends fixedly connected with the elastic body; the axis of the first optical fiber is collinear with the axis of the elastic body, the two ends of the first optical fiber are fixed at the two ends of the elastic body, the first optical fiber at least comprises a first section penetrating through the hollow pipe and a second section fixed on the beam plate, and a first fiber bragg grating and a second fiber bragg grating are engraved on the first section and the second section respectively; at least parts of the second optical fibers are symmetrically arranged on the two sides of the second section of the first optical fiber, the plane where the parts of the second optical fibers are located is parallel to the surface of the beam plate, the two ends of the second optical fibers are fixed to the elastic body, and a third fiber bragg grating and a fourth fiber bragg grating are carved on the second optical fibers respectively. Through the arrangement, the assembly error is reduced, the robustness is high, and miniaturization is easy.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, and in particular to a three-dimensional force sensor and a decoupling method. Background Art

[0002] During robot-assisted minimally invasive surgery, surgeons will lose tactile information because they do not have direct contact with the patient. Real-time force feedback is very important for surgeons' diagnosis. The information of contact force ensures the safety of surgery and improves the success rate of surgery. Therefore, contact force sensors play a vital role here. They can provide surgeons with real-time force feedback when micro medical instruments interact with tissues.

[0003] Compared with electrical force sensors, optical force sensors have many unique advantages, such as strong anti-electromagnetic interference ability, easier compatibility with radiofrequency ablation devices, small size, good flexibility, high sensitivity and good physiological compatibility. In optical force sensors, wavelength modulation sensors modulate force information into the light beam by changing the wavelength in the optical fiber. Fiber Bragg grating (FBG) is the most commonly used wavelength modulation sensor. Using optical fiber engraved with FBG as a sensing element can overcome the limitations of light intensity fluctuations and phase discontinuity, and has high sensitivity and good biocompatibility.

[0004] Since the force sensor needs to be integrated into a miniature medical device, a simple tubular structure is the most compatible with it. However, its lateral stiffness is significantly greater than its axial stiffness. This difference will lead to increased sensor errors and reduced stability.

[0005] In order to balance the lateral and axial stiffness of the sensor, achieve a balance in sensitivity in three directions and maintain isotropy, the existing technology adopts methods such as adding ablation electrodes / leaf springs and setting four / five or even more optical fibers. This will increase the complexity of the structure, increase the difficulty of assembly, easily introduce assembly errors, make it difficult to achieve miniaturization, and is not conducive to large-scale application in engineering. Summary of the invention

[0006] In order to solve the defects of the existing three-dimensional force sensor, such as complex structure, great assembly difficulty and low degree of miniaturization, the present invention proposes a three-dimensional force sensor and a decoupling method.

[0007] The technical solution adopted by the present invention is a three-dimensional force sensor, comprising: an elastic body, wherein the elastic body includes region one and region two along its axial direction, wherein region one is a beam plate with two ends fixedly connected to the elastic body, and region two is a hollow tube with two ends fixedly connected to the elastic body; a first optical fiber, wherein the axis thereof is colinear with the axis of the elastic body, and the two ends thereof are fixed to the two ends of the elastic body, wherein the first optical fiber at least includes a first section passing through the hollow tube and a second section fixed to the beam plate, wherein the first section and the second section are respectively engraved with a first optical fiber grating and a second optical fiber grating; a pair of second optical fibers, wherein at least part of them are symmetrically arranged on both sides of the second section of the first optical fiber, and the plane where the part of the second optical fibers is located is parallel to the surface of the beam plate, wherein both ends of the pair of second optical fibers are fixed to the elastic body, and the pair of second optical fibers are respectively engraved with a third optical fiber grating and a fourth optical fiber grating.

[0008] Preferably, a hollow structure is provided on at least a portion of the surface of the hollow tube.

[0009] Preferably, the central wavelengths of the third fiber grating and the fourth fiber grating are equal.

[0010] Preferably, the elastomer also includes a base and a top cover, and the top cover, hollow tube, beam plate and base are fixedly connected in sequence, the two ends of the first optical fiber are fixedly connected to the base and the top cover respectively, and the two ends of a pair of the second optical fibers are fixedly connected to the base and the hollow tube respectively.

[0011] Preferably, a groove is provided on the elastic body at a position where the first optical fiber and the second optical fiber are connected, and the first optical fiber and a pair of the second optical fibers are bonded and fixed to the inner wall of the groove.

[0012] Preferably, the elastic body is made of stainless steel or epoxy resin.

[0013] The present invention also proposes a three-dimensional force decoupling method based on the above-mentioned three-dimensional force sensor, the method comprising: setting the three-dimensional force sensor at a position to be measured so that the axis of the elastic body is oriented in the Z direction and the plate surface of the beam plate is perpendicular to the X direction and parallel to the Y direction; constructing the strain of the second fiber grating in the X and Y directions, and obtaining that the strain of the second fiber grating in the Y direction is 0.

[0014] Preferably, the method further comprises: obtaining the central wavelength and wavelength drift of the second fiber Bragg grating, and the effective photoelastic coefficient of the first optical fiber; and decoupling the strain in the X direction according to the central wavelength and wavelength drift of the second fiber Bragg grating, and the effective photoelastic coefficient of the first optical fiber.

[0015] Preferably, the method further includes: respectively acquiring the central wavelength and wavelength drift of the third fiber grating and the fourth fiber grating, and the effective photoelastic coefficient of the second optical fiber; and decoupling the strain in the Y direction according to the central wavelength and wavelength drift of the third fiber grating and the fourth fiber grating, and the effective photoelastic coefficient of the second optical fiber.

[0016] Preferably, the method further comprises: acquiring the central wavelength and wavelength drift of the first fiber grating; and decoupling the strain in the Z direction according to the central wavelength and wavelength drift of the first fiber grating and the effective photoelastic coefficient of the first optical fiber.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention arranges two sections of specific elastic body structures, namely, a beam plate and a hollow tube, on a first optical fiber, and symmetrically arranges a pair of second optical fibers on both sides of the first optical fiber located at the beam plate part, and then engraves four fiber Bragg gratings, namely, a first fiber grating, a second fiber grating, a third fiber grating and a fourth fiber grating, on the first optical fiber and the pair of second optical fibers. By measuring the strains on the four fiber Bragg gratings respectively, the forces of the three-dimensional force sensor in the three directions of X, Y and Z can be decoupled, and the balance of the three-axis force sensitivity is achieved, and the isotropy of the three-dimensional force sensor is maintained. There is no need to use four or more optical fibers, which reduces the use of optical fibers, and there is no need to add additional components such as ablation electrodes / leaf springs. The structure is simple, the assembly difficulty is low, and the assembly error is reduced. The integrated elastomer is used, the robustness is strong, and it is easy to miniaturize. It can be conveniently integrated into micro medical equipment to measure high-precision contact force information, which is convenient for large-scale application in engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention is described in detail below with reference to the embodiments and accompanying drawings, wherein:

[0020] Figure 1 is a schematic diagram of a three-dimensional force sensor;

[0021] Figure 2 This is the internal structure diagram of the three-dimensional force sensor;

[0022] Figure 3 It is the force diagram of beam and slab;

[0023] Figure 4 This is a partial structural exploded diagram of the three-dimensional force sensor;

[0024] Figure 5 It is a partial structural schematic diagram of a three-dimensional force sensor.

[0025] 1. first optical fiber; 2. second optical fiber; 3. second optical fiber; 4. elastic body;

[0026] 1.1, Region 1; 1.2, Region 2;

[0027] 2.1, first fiber Bragg grating; 2.2, second fiber Bragg grating; 2.3, third fiber Bragg grating; 2.4, fourth fiber Bragg grating;

[0028] 4.1, beam and slab; 4.2, hollow tube; 4.3, top cover; 4.4, base; 4.5, groove. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar components or components with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be interpreted as limiting the present invention.

[0030] In one embodiment, Figure 1-2 As shown, a three-dimensional force sensor includes an elastic body 4, a first optical fiber 1 and a pair of second optical fibers 2 (3). The elastic body 4 includes a region 1.1 and a region 2 1.2, which are arranged in sequence along the axial direction of the elastic body 4. The region 1.1 is a beam plate 4.1, and both ends of the beam plate 4.1 are fixedly connected to the elastic body 4. The region 2 1.2 is a hollow tube 4.2, and both ends of the hollow tube 4.2 are fixedly connected to the elastic body 4.

[0031] The axis of the first optical fiber 1 is colinear with the axis of the elastic body 4, and its two ends are fixed at the two ends of the elastic body 4. The first optical fiber 1 includes a first section that penetrates the hollow tube 4.2 and a second section that is fixed on the beam plate 4.1. The first section and the second section are respectively engraved with a first fiber grating 2.1 and a second fiber grating 2.2, so that the first fiber grating 2.1 disposed in the hollow tube 4.2 is only sensitive to the force in the Z direction, and the second fiber grating 2.2 disposed on the beam plate 4.1 is only sensitive to the force in the X direction. By measuring and decoupling the strains of the first fiber grating 2.1 and the second fiber grating 2.2, the force values ​​of the three-dimensional force sensor in the X direction and the Z direction can be obtained.

[0032] like Figure 4-, a pair of second optical fibers 2 (3) are symmetrically arranged on both sides of the second section of the first optical fiber 1, the plane where the pair of second optical fibers 2 (3) are located is parallel to the surface of the beam plate 4.1, both ends of the pair of second optical fibers 2 (3) are fixed on the elastic body 4, and the pair of second optical fibers 2 (3) are respectively engraved with a third fiber grating 2.3 and a fourth fiber grating 2.4, so that the third fiber grating 2.3 and the fourth fiber grating 2.4 are sensitive to forces in the X and Y directions at the same time, and the force value of the three-dimensional force sensor in the Y direction can be obtained by measuring and decoupling the strains of the third fiber grating 2.3 and the fourth fiber grating 2.4.

[0033] In this embodiment, two sections of specific elastic body 4 structures, namely, beam plate 4.1 and hollow tube 4.2, are arranged on the first optical fiber 1, and a pair of second optical fibers 2(3) are symmetrically arranged on both sides of the first optical fiber 1 located at the beam plate 4.1. Then, four fiber Bragg gratings, namely, a first fiber grating 2.1, a second fiber grating 2.2, a third fiber grating 2.3 and a fourth fiber grating 2.4, are engraved on the first optical fiber 1 and the pair of second optical fibers 2(3). By measuring the strains on the four fiber Bragg gratings respectively, the forces of the three-dimensional force sensor in the three directions of X, Y and Z can be decoupled, and the balance of the three-axis force sensitivity is achieved, and the isotropy of the three-dimensional force sensor is maintained. There is no need to use four or more optical fibers, which reduces the use of optical fibers, and there is no need to add additional components such as ablation electrodes / leaf springs. The structure is simple, the assembly difficulty is low, and the assembly error is reduced. The integrated elastic body 4 is used, the robustness is strong, and it is easy to miniaturize. It can be easily integrated into micro medical equipment to measure high-precision contact force information, which is convenient for large-scale application in engineering.

[0034] In other embodiments, the first optical fiber 1 may also include portions other than the first segment and the second segment, and a pair of second optical fibers 2 (3) may also include portions other than the two sides of the second segment of the first optical fiber 1, which can be adjusted according to the convenience of actual production and assembly.

[0035] In one embodiment, a hollow structure is provided on part of the surface of the hollow tube 4.2, and the hollow structure can be a through rectangular groove, a cross groove or a spiral groove, etc. The hollow structure provided on the surface of the hollow tube 4.2 can improve its axial sensitivity, and facilitate the acquisition of the Z-direction force value of the three-dimensional sensor. The larger the area of ​​the hollow structure on the surface of the hollow tube 4.2, the higher the sensitivity of the hollow tube 4.2, and the surface of the hollow tube 4.2 can be set as a hollow structure.

[0036] In one embodiment, the central wavelengths of the third fiber grating 2.3 and the fourth fiber grating 2.4 are equal to simplify the calculation.

[0037] In one embodiment, the elastic body 4 further includes a base 4.4 and a top cover 4.3, and the top cover 4.3, the hollow tube 4.2, the beam plate 4.1 and the base 4.4 are fixedly connected in sequence to form an integrated elastic body 4, which has a more stable and reliable structure. The two ends of the first optical fiber 1 are respectively fixedly connected to the base 4.4 and the top cover 4.3, and the two ends of a pair of second optical fibers 2 (3) are respectively fixedly connected to the base 4.4 and the hollow tube 4.2, and the structural integrity is stronger.

[0038] Specifically, grooves 4.5 are provided at the positions where the first optical fiber 1 and the second optical fiber 2(3) are connected on the elastic body 4, that is, three grooves 4.5 are provided on the base 4.4, and the ends of the first optical fiber 1 and the pair of second optical fibers 2(3) extend into the three grooves 4.5 respectively; a long groove 4.5 is provided on the beam plate 4.1 along the axis of the elastic body 4, and the first optical fiber 1 is embedded in the long groove 4.5; a groove 4.5 is provided at the end or inner wall of the hollow tube 4.2, and the other end of the pair of second optical fibers 2(3) away from the base 4.4 extends into the groove 4.5; a groove 4.5 is provided on the inner surface of the top cover 4.3, and the end of the first optical fiber 1 away from the base 4.4 extends into the groove 4.5. The first optical fiber 1 and the pair of second optical fibers 2(3) can be bonded and fixed to the inner walls of the corresponding grooves 4.5 by medical grade glue, and the medical glue can be medical instant glue, medical epoxy resin glue or medical UV glue. The groove 4.5 can increase the bonding contact surface, making the connection between the first optical fiber 1 and a pair of second optical fibers 2 (3) and the elastomer 4 more stable.

[0039] In other embodiments, the first optical fiber 1 and the pair of second optical fibers 2 (3) may be fixedly connected to the inner walls of the corresponding grooves 4.5 by welding or the like.

[0040] In one embodiment, the material of the elastomer 4 can be stainless steel, such as 304 stainless steel, which has good biocompatibility. The material of the elastomer 4 can also be epoxy resin, such as using medical epoxy resin glue (EP42HT-2Med) for 3D printing to reduce production costs.

[0041] In one embodiment, a three-dimensional force decoupling method is provided, based on the three-dimensional force sensor in the above embodiment, and the method includes:

[0042] The three-dimensional force sensor is arranged at the position to be measured, so that the axis of the elastic body 4 is oriented in the Z direction, and the plate surface of the beam plate 4.1 is perpendicular to the X direction and parallel to the Y direction;

[0043] The strains of the second fiber grating 2.2 in the X and Y directions are constructed, and it is found that the strain of the second fiber grating 2.2 in the Y direction is zero.

[0044] Specifically, the length of the beam plate 4.1 in area 1.1 is L1, and the length of the hollow tube 4.2 in area 2.2 is L2. The above dimensions L1, L2, the thickness of the beam plate 4.1, and the width of the rectangular groove on the surface of the hollow tube 4.2 can be designed according to the size of the connected instrument and the resolution and accuracy of the force to be measured to control the stiffness in three directions respectively.

[0045] For beam-slab 4.1, when the end of its upper surface is subjected to lateral force, if Figure 3 As shown, it can be decomposed into two forces in the X direction perpendicular to the beam plate 4.1 and the Y direction parallel to the beam plate 4.1. The strain on the second section of the first optical fiber 1 can be obtained by the following formula:

[0046]

[0047] Among them, ε x , ε y1 are the strains in the X and Y directions of the region where the second fiber grating is located in the first fiber, M is the bending moment, and r x 、r y are the distances between the first optical fiber and the bending axis (i.e., the axis of the elastic body) in the X and Y directions, E is the elastic modulus of the beam, and I x ,I y are the moments of inertia of the beam and slab in the X and Y directions respectively, b and d are the lengths of the long and short sides of the beam and slab respectively, and b is much larger than d.

[0048] From the above formula, we can know that the moment of inertia of the first optical fiber in the X direction is much smaller than that in the Y direction, and the first optical fiber is at the bending axis position in the Y direction. At this time, r y is zero, so the strain of the first optical fiber in the X direction is much greater than the strain in the Y direction, and the strain of the first optical fiber in the Y direction is almost 0. This decoupling method of the beam and plate can well decouple the strain it is subjected to in the X direction.

[0049] In one embodiment, the three-dimensional force decoupling method further includes:

[0050] Obtaining the central wavelength and wavelength drift of the second fiber grating, and the effective photoelastic coefficient of the first optical fiber;

[0051] The strain in the X direction is decoupled according to the central wavelength and wavelength drift of the second fiber grating and the effective photoelastic coefficient of the first optical fiber.

[0052] Specifically, when the three-dimensional force sensor is subjected to a lateral force, it can be known from the above that ε y1 is 0, then the relationship between the wavelength drift Δλ2 of the second fiber grating and the corresponding strain change on the second segment of the first optical fiber can be determined as:

[0053]

[0054] Where λ2 is the central wavelength corresponding to the second fiber grating, ρ e is the effective photoelastic coefficient of the first optical fiber. This method can decouple the strain of the three-dimensional force sensor in the X direction, thereby accurately obtaining the force it is subjected to in the X direction.

[0055] In one embodiment, the three-dimensional force decoupling method further includes: respectively obtaining the central wavelength and wavelength drift of the third fiber grating and the fourth fiber grating, and the effective photoelastic coefficient of the second optical fiber;

[0056] The strain in the Y direction is decoupled according to the central wavelength and wavelength shift of the third fiber grating and the fourth fiber grating, and the effective photoelastic coefficient of the second optical fiber.

[0057] Specifically, when the three-dimensional force sensor is subjected to a lateral force, the strains on the third fiber Bragg grating and the fourth fiber Bragg grating can be decomposed into two parts: the strain ε caused by the force in the X direction and x3 , ε x4 and the strain ε caused by the force in the Y direction y3 , ε y4 Due to the symmetrical structural design, when the third fiber grating and the fourth fiber grating sense the force in the X direction, the strains in the areas where the third fiber grating and the fourth fiber grating are located are equal, and both are compressed or stretched; when the third fiber grating and the fourth fiber grating sense the force in the Y direction, the strains in the areas where the third fiber grating and the fourth fiber grating are located are equal, but in opposite directions. The relationship is as follows:

[0058]

[0059] Among them, ε x1 represents the strain caused by the third and fourth fiber Bragg gratings when subjected to the lateral force in the X direction, ε y 、-ε y They represent the strains caused by the third fiber Bragg grating and the fourth fiber Bragg grating when subjected to the lateral force in the Y direction. Assuming that the temperature is constant, when the three-dimensional force sensor is subjected to the lateral force, the relationship between the wavelength drifts Δλ3 and Δλ4 of the third fiber Bragg grating and the corresponding strain changes on the third fiber Bragg grating and the fourth fiber Bragg grating can be determined as follows:

[0060]

[0061] Where λ3 and λ4 are the center wavelengths of the third and fourth fiber Bragg gratings, respectively, and ρ eis the effective photoelastic coefficient of the second optical fiber pair. For the sake of simplicity, the central wavelengths of the third and fourth fiber gratings are equal. The decoupled strain result in the Y direction can be determined by subtracting the two equations and is derived as follows:

[0062]

[0063] At this time, the strain in the Y direction can be decoupled by the differential decoupling of the third fiber grating and the fourth fiber grating, so as to accurately calculate the lateral force received by the three-dimensional force sensor in the Y direction.

[0064] In one embodiment, the three-dimensional force decoupling method further includes:

[0065] Obtaining the central wavelength and wavelength drift of the first fiber grating;

[0066] The strain in the Z direction is decoupled according to the central wavelength and wavelength drift of the first fiber grating and the effective photoelastic coefficient of the first optical fiber.

[0067] Specifically, when the sensor is subjected to an axial force, the relationship between the wavelength drift Δλ1 of the first fiber grating and the corresponding strain change on the first optical fiber can be determined as follows:

[0068]

[0069] Where λ1 is the central wavelength corresponding to the first fiber grating, ε z is the strain change of the first fiber Bragg grating when subjected to axial force, ρ e is the effective photoelastic coefficient of the first optical fiber. This method can decouple the strain of the three-dimensional force sensor in the Z direction, thereby accurately obtaining the force it is subjected to in the Z direction.

[0070] After theoretical derivation and subsequent finite element simulation, the first fiber Bragg grating can decouple the axial force in the Z direction of the three-dimensional force sensor, the second fiber Bragg grating can decouple the lateral force in the X direction, and the third and fourth fiber Bragg gratings can decouple the lateral force in the Y direction. Through the method of segmented sensitivity and differential decoupling design, the strain produces sensitivity specificity, thereby decoupling the three-dimensional force. This configuration can effectively overcome the crosstalk between the three-axis forces, improve the measurement accuracy, and keep the three-dimensional force sensor isotropic. It has obvious sensitivity specificity, high linearity, and low crosstalk, which can stably measure the three-dimensional force.

[0071] The three-dimensional force sensor and decoupling method of the present invention can not only be used to obtain contact force information in minimally invasive surgical palpation, but also can be used for distal force sensing of catheters, such as interventional surgery.

[0072] In the description of this specification, if the terms "embodiment one", "this embodiment", "in an embodiment" and the like appear, it means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in the invention or at least one embodiment or example of the invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example; moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in an appropriate manner.

[0073] In the description of this specification, the terms "connect", "install", "fix", "set", "have", etc. are all understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0074] In the description of this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0075] The above description of the embodiments is to facilitate ordinary technicians in the technical field to understand and apply the technology of this case. People familiar with the technology in this field can obviously easily make various modifications to these examples and apply the general principles described here to other embodiments without creative work. Therefore, this case is not limited to the above embodiments. Modifications to the following situations should all be within the scope of protection of this case: ① A new technical solution implemented based on the technical solution of the present invention and combined with existing common knowledge, the technical effect produced by the new technical solution does not exceed the technical effect of the present invention; ② The equivalent replacement of some features of the technical solution of the present invention by using known technology, the technical effect produced is the same as the technical effect of the present invention; ③ The technical solution of the present invention can be expanded, and the substantive content of the expanded technical solution does not exceed the technical solution of the present invention; ④ The equivalent transformation made by using the contents of the description and drawings of the present invention is directly or indirectly applied to other related technical fields.

Claims

1. A three-dimensional force sensor, It is characterized in that include: An elastic body, wherein the elastic body includes a first region and a second region along its axial direction, wherein the first region is a beam plate with two ends fixedly connected to the elastic body, and the second region is a hollow tube with two ends fixedly connected to the elastic body; A first optical fiber, whose axis is colinear with the axis of the elastic body and whose two ends are fixed to the two ends of the elastic body, wherein the first optical fiber at least comprises a first section penetrating the hollow tube and a second section fixed to the beam plate, wherein the first section and the second section are respectively engraved with a first optical fiber grating and a second optical fiber grating; A pair of second optical fibers are at least partially symmetrically arranged on both sides of the second section of the first optical fiber, and the plane where the second optical fibers are located is parallel to the surface of the beam plate. Both ends of the pair of second optical fibers are fixed on the elastomer, and the pair of second optical fibers are respectively engraved with a third fiber grating and a fourth fiber grating.

2. The three-dimensional force sensor according to claim 1, It is characterized in that At least a portion of the surface of the hollow tube is provided with a hollow structure.

3. The three-dimensional force sensor according to claim 1, It is characterized in that The central wavelengths of the third fiber grating and the fourth fiber grating are equal.

4. The three-dimensional force sensor according to claim 2, It is characterized in that The elastomer also includes a base and a top cover, the top cover, hollow tube, beam plate and base are fixedly connected in sequence, the two ends of the first optical fiber are respectively fixedly connected to the base and the top cover, and the two ends of a pair of the second optical fibers are respectively fixedly connected to the base and the hollow tube.

5. The three-dimensional force sensor according to claim 4, It is characterized in that A groove is formed on the elastic body at a position where the first optical fiber and the second optical fiber are connected, and the first optical fiber and a pair of the second optical fibers are bonded and fixed to the inner wall of the groove.

6. The three-dimensional force sensor according to claim 1, It is characterized in that The elastic body is made of stainless steel or epoxy resin.

7. A three-dimensional force decoupling method, based on the three-dimensional force sensor according to any one of claims 1 to 5, It is characterized in that The method comprises: The three-dimensional force sensor is arranged at a position to be measured, so that the axis of the elastic body is oriented in the Z direction, and the plate surface of the beam plate is perpendicular to the X direction and parallel to the Y direction; The strains of the second fiber grating in the X and Y directions are constructed, and it is learned that the strain of the second fiber grating in the Y direction is 0.

8. The three-dimensional force decoupling method according to claim 7, It is characterized in that The method further comprises: Acquire the central wavelength and wavelength drift of the second fiber grating, and the effective photoelastic coefficient of the first optical fiber; The strain in the X direction is decoupled according to the central wavelength and wavelength drift of the second fiber grating and the effective photoelastic coefficient of the first optical fiber.

9. The three-dimensional force decoupling method according to claim 8, It is characterized in that The method further comprises: Respectively obtaining the central wavelength and wavelength drift of the third fiber grating and the fourth fiber grating, and the effective photoelastic coefficient of the second optical fiber; The strain in the Y direction is decoupled according to the central wavelength and wavelength drift of the third and fourth fiber gratings, and the effective photoelastic coefficient of the second optical fiber.

10. The three-dimensional force decoupling method according to claim 9, It is characterized in that The method further comprises: Obtaining the central wavelength and wavelength drift of the first fiber grating; The strain in the Z direction is decoupled according to the central wavelength and wavelength drift of the first fiber grating and the effective photoelastic coefficient of the first optical fiber.

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